UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The relationship of interfacial energy to graphite shape in the Fe-C system. Hawbolt, Edward Bruce 1964

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1964_A7 H38.pdf [ 15.08MB ]
Metadata
JSON: 831-1.0093737.json
JSON-LD: 831-1.0093737-ld.json
RDF/XML (Pretty): 831-1.0093737-rdf.xml
RDF/JSON: 831-1.0093737-rdf.json
Turtle: 831-1.0093737-turtle.txt
N-Triples: 831-1.0093737-rdf-ntriples.txt
Original Record: 831-1.0093737-source.json
Full Text
831-1.0093737-fulltext.txt
Citation
831-1.0093737.ris

Full Text

THE RELATIONSHIP OF INTERFACIAL ENERGY TO GRAPHITE SHAPE I N THE Fe-C SYSTEM  BY  EDWARD BRUCE HAWBOLT B.A.Sc, The U n i v e r s i t y o f B r i t i s h C o l u m b i a ,  i960  A THESIS SUBMITTED I N PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE.DEGREE OF MASTER OF APPLIED. SCIENCE i n t h e Department of METALLURGY  We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e standard required  from c a n d i d a t e s f o r t h e  degree o f MASTER OF APPLIED SCIENCE.  Members o f t h e Department o f Metallurgy . THE UNIVERSITY OF BRITISH COLUMBIA August 1964  In the  r e q u i r e m e n t s f o r an  British  mission  for reference  for extensive  p u r p o s e s may  be  cation  of  written  Department  of  by  study.  the  Library  Head o f my  Metallurgy  1964  Columbia,  fulfilment  University  shall  this thesis  permission*  September 4,  the  I further  agree for  of •  t h a t per.-?  scholarly  Department  shall  of  make i t f r e e l y  or  t h a t , c o p y i n g or  for f i n a n c i a l gain  .The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, Canada  Date  the  c o p y i n g of  in partial  degree at  I t i s understood  this thesis  w i t h o u t my  that  and  granted  representatives.  this thesis  advanced  Columbia, I agree  available  his  presenting  not  be  by publi-  allowed  ABSTRACT The r e l a t i o n s h i p between s u r f a c e energy and p r e c i p i t a t e d form i n Fe-C a l l o y s was examined i n t h i s t h e s i s .  graphite  -Surface t e n s i o n and  c o n t a c t a n g l e data were o b t a i n e d u s i n g the s e s s i l e drop t e c h n i q u e .  Carbon  s a t u r a t e d , puron i r o n c r u c i b l e s were melted on p y r o l y t i c g r a p h i t e , t h e e f f e c t o f time, temperature ( 1 5 0 0 - l 6 0 0 ° C ) and a d d i t i o n s o f N i y Mn,.S o r Ce b e i n g examined.  The g r a p h i t e form;was e s t a b l i s h e d . b y  metallographic  examination. o f H 5 2 dynes/cm was determined f o r t h e Fe-C  An average alloys  {h.6$ C) a t a p p r o x i m a t e l y  1300°C, the average c o n t a c t angle b e i n g .128°.  No s i g n i f i c a n t change o c c u r r e d w i t h a d d i t i o n s o f . N i ( and'-Mn (  1.65$) •  0.85$)  A d d i t i o n s o f S lowered t h e s u r f a c e energy and i n c r e a s e d  the e q u i l i b r i u m c o n t a c t a n g l e .  Ce a d d i t i o n s had a s i m i l a r e f f e c t  although  a d i r e c t comparison w i t h the Fe-C a l l o y s c o u l d n o t be made as d i f f e r e n t temperatures were used.  However, t h e i n t e r f a c i a l energy d i f f e r e n c e a p p a r e n t l y  i n c r e a s e d w i t h i n c r e a s i n g Ce c o n t e n t , graphite-melt  i m p l y i n g an a d s o r p t i o n o f Ce t o t h e  interface.  The change f r o m t h e f l a k e t o t h e n o d u l a r  form was  accomplished  i n s e v e r a l t r a n s i t i o n s t a g e s , t h e i n t e r f a c i a l energy d i f f e r e n c e s b e i n g s m a l l , i n d i c a t i n g a marked dependence on the s o l i d i f i c a t i o n and growth conditions.  ACKNOWLEDGEMENT  The a u t h o r g r a t e f u l l y acknowledges  t h e a d v i c e and guidance  g i v e n . b y P r o f e s s o r W. M. Armstrong throughout t h e i n v e s t i g a t i o n . .The a u t h o r i s e s p e c i a l l y i n d e b t e d - t o Mrs. A. M. Armstrong i n i n t e r p r e t i n g and p r e p a r i n g t h e f i n a l m a n u s c r i p t .  f o r assistance Thanks a r e a l s o  extended t o R. G. B u t t e r s / R. J . R i c h t e r and P..R..Musil f o r t h e i r t e c h n i c a l a s s i s t a n c e and t o f e l l o w graduate s t u d e n t s and o t h e r f a c u l t y members f o r t h e i r h e l p f u l d i s c u s s i o n s .  F i n a n c i a l support was r e c e i v e d from t h e Defence R e s e a r c h Board o f Canada under Grant No.. 7501-02 and from t h e A l u m i n i u m ' L a b o r a t o r i e s i n t h e form o f a graduate r e s e a r c h f e l l o w s h i p . acknowledged.  T h i s support i s g r a t e f u l l y  TABLE OF CONTENTS Page •.I. • INTRODUCTION  1  A. .General D i s c u s s i o n o f C a s t B. Background Theory  Irons  1  . . . . . . . . . . . . . . . . . . . . . . .  1 . . T h e • S u r f a c e T e n s i o n Parameter  . 2  . . . . . . . . . . .  . 2  2 . . The R e l a t i o n s h i p o f S u r f a c e Energy t o P r e c i p i t a t i n g Form 3.  3  The E f f e c t o f S o l u t e A d d i t i o n s on I n t e r f a c i a l Energy  k  C. .Review o f Previous:Work  6  1 . . S u r f a c e T e n s i o n Measurements -  6  2 . S o l i d i f i c a t i o n of a Hypereutectic Iron  . . . . .  a. . E f f e c t 'of. A l l o y A d d i t i o n s b. . E f f e c t 3.  9  . 1  o f C o o l i n g Rate on S t r u c t u r e  . . . .  S o l i d i f i c a t i o n of a Hypereutectic Nodular I r o n  2  . 1 3  .  1*4-  ^ . . R e l a t i o n s h i p Between I n t e r f a c i a l Energy and G r a p h i t e Form D. S e s s i l e E. Choice  Drop Technique  . . . . . . . . . .  o f System and Aim o f I n v e s t i g a t i o n . . . . . . .  I I . EXPERIMENTAL  1  7  1  9 . 2 2  . . .  B. • Apparatus  I I I . RESULTS  6  . .  • A.. M a t e r i a l s Used  C. E x p e r i m e n t a l  1  . 2 2  .  . 2k  Procedure  2k .  2  7  continued...  .Table  of Contents  Continued... Page  A.  S e s s i l e Drop R e s u l t s 1.  Basic Iron-Carbon  2..Effect  27 Alloy .  .  .  . . . .  of N i and M n - A d d i t i o n s .  .  .  . . .  . ..  .  27  .  ...  .  .JO  ...  : 3 . . E f f e c t o f Sulphur A d d i t i o n s  30  A . . E f f e c t of Ce A d d i t i o n s  32  B. R e s u l t s o f M e t a l l o g r a p h i c 1.  . . . . . . . . . . . . .  Examination  . . . . . . .  36  Fe-C A l l o y  .36  2 . E f f e c t of N i and'Mn A d d i t i o n s  .  .  38  3 . . E f f e c t of Sulphur A d d i t i o n s  38  k.  hi  E f f e c t of Ce A d d i t i o n s  C .• Thermodynamic  Calculations.  .. . . . . . . . . . . . . . . .  IV.  DISCUSSION AND CONCLUSIONS  V.  RECOMMENDATIONS FOR FUTURE WORK . . . . . . . . . . . . .  VI.  APPENDICES  V I I . REFERENCES  .  52 .  55 6l .62  .  79  LIST OF FIGURES Figure 1.  .  Page  a. K e v e r i a n ' s  Data Showing  b.. K o z a k e v i t c h ' s 2. 3. 4.  .  .Graphite  Development  10  i n a Hypereutectic  S t a b i l i t y of Graphite.Versus  Graphite  11  Alloy  F e C as A f f e c t e d by C o o l i n g 3  .13  . Form a's R e l a t e d ' t o . S p e c i f i c - A r e a s ' i n . the Fe-C  15  Diagram 6.  Growth C h a r a c t e r i s t i c s o f a G r a p h i t e  7.  O u t l i n e o f S e s s i l e Drop  8. 9.  .Forces  Present  .........  .16  . . . . . . . . .  18  Nodule  a t the Drop, I n t e r f a c e  .. .  .18 25  Apparatus  10.  Fe-C Data Showing the E f f e c t o f Time and Temperature on  11.  the C o n t a c t Angle Comparison o f t h e W e t t i n g C h a r a c t e r i s t i c s o f an Fe-C  29  J>0  A l l o y and Pur on I r o n 12.  Drop S i l h o u e t t e s Showing the E f f e c t - o f S A d d i t i o n s  13.  S i l h o u e t t e s o f Drop. C o n t a i n i n g Ce  14.  E f f e c t of. I n c r e a s i n g Temperature on t h e Ce A l l o y Contact  . . .  31 33  . J>k  Angles 15.  General-Structure  16.  C r y s t a l s Remaining on Base P l a t e i n Fe-C T e s t  17.  S t r u c t u r e o f the Fe-C-Ni A l l o y  18.  S t r u c t u r e o f the Fe-C-Mn A l l o y ,  • 19.  8 8  Data Showing the E f f e c t o f S and C on l^^y*  Fe-C E q u i l i b r i u m Diagram  Rate 5.  Versus A c t i v i t y S . . . . .  37  o f Fe-C Drops  .38 -.  39 40  Structure of the High S A l l o y s  kl  20.  S t r u c t u r e o f t h e Low S A l l o y s  21.  S h r i n k a g e o f a 0 . 0 5 $ Ce A l l o y  43  22.  S t r u c t u r e o f a Low-Ce A l l o y  46  ..  k2  List  of Figures Continued.  Figure  Page  23.  S t r u c t u r e o f a 0.0k  wt.fo Ce A l l o y .  2k.  S t r u c t u r e o f a O.O5  wt,$  Ce A l l o y  •25.  • S t r u c t u r e s o f the Master A l l o y s  26.  Structure of P y r o l y t i c Graphite  V7 .kg 51 66:  • LIST. OF TABLES Page Table I .  Analyses  Table I I .  "Y 's and-Contact * • LV  Table I I I .  of Materials  The Change i n Y  LV  0  Used  23  Angles f o r the Fe-C with * 0 . 0 1 "  z. Parameter . . . . . . . . . . Table IV. T a b l e V.  ^ > s  and C o n t a c t Angles  • J_iV  tf-Lv'  3  a  n  d  C o n t a c t Angles  ....  . ...  . . . . ...  ...  .28  f o r the Fe-C-S A l l o y s  . .  32  f o r the Fe-C-Ce A l l o y s  I n t e r f a c i a l Energy C a l c u l a t i o n s  Table V I I .  Probe Scan R e s u l t s f o r Fe-C-Ce A l l o y  Table V I I I .  Spectrographs  Average A n a l y s e s  .  . . . . . . . . . . . ..........  . .35 45  on Top and' Bottom of  Drop Sample T a b l e IX.  28  V a r i a t i o n i n the  Table VI.  Ce A n a l y s e s  Alloys  kQ of A l l o y A f t e r T e s t  . . . \. . . . . 1  50  LIST OF'APPENDICES Page I.  . - E x p e r i n e n t e A D i f f i c u l t i . e s and' E r r o r s Inherent i n the S e s s i l e Drop: Approach  . . . . . . . . . . . . . .  62  II.  P r o d u c t i o n and P r o p e r t i e s o f P y r o l y t i c G r a p h i t e  . . .  65  III.  S e s s i l e Drop Data  . . .  67  IV.  S t a t i s t i c a l A n a l y s i s o f Three Fe-C T e s t s  V.  C o o l i n g Rate C o n s i d e r a t i o n s  . . . . . . .  .........  73 76  I.  INTRODUCTION A. G e n e r a l Cast  the range 1.7 as a . c a r b i d e  Discussion of Cast  Irons  i r o n s comprise a l a r g e group o f Fe-C a l l o y s w i t h carbon i n t o 6.7  wt..$.  I n the s o l i d i f i e d a l l o y , t h e carbon may  o r as f r e e g r a p h i t e .  v a r i e t y o f forms.  occur  Moreover, the g r a p h i t e may assume a  S i n c e t h e p h y s i c a l p r o p e r t i e s o f a composite m a t e r i a l  a r e s t r o n g l y , dependent on i t s m i c r o s t r u c t u r e b o t h t h e shape and d i s t r i b u t i o n o f the r e l a t i v e l y weak, d i s p e r s e d g r a p h i t e phase a r e o f major s i g n i f i c a n c e i n determining  The and  the f i n a l strength c h a r a c t e r i s t i c s of a cast  microstructure  impurity content,  iron.  i s dependent on t h e carbon c o n t e n t ,  the a l l o y  the c o o l i n g . r a t e d u r i n g and a f t e r f r e e z i n g and the  c o n d i t i o n s o f heat t r e a t m e n t .  While t h e g e n e r a l e f f e c t s o f these v a r i a b l e s  on t h e r e s u l t i n g m i c r o s t r u c t u r e a r e w e l l known, t h e d e t a i l s o f t h e f o r m a t i o n and  growth mechanisms o p e r a t i n g a r e s t i l l not completely, u n d e r s t o o d .  • The most pronounced change i n . the shape o f t h e g r a p h i t e phase i s from t h e f l a k e form o f grey In t h e p r o d u c t i o n  of nodular  i r o n t o t h e s p h e r o i d a l form o f n o d u l a r  o r d u c t i l e i r o n a s p h e r o i d i z i n g agent, e i t h e r  Mg as a NiMg o r FeSiMg a l l o y , o r Ce as mischmetal (an a l l o y o f r a r e c o n t a i n i n g 5 0 $ Ce) i s added t o a g r e y the melt from t h e f u r n a c e .  iron.  i r o n composition  earths  following.tapping of  The;, g r a p h i t e i n t h e s o l i d i f i e d a l l o y i s t h e r e b y  changed from a f l a k e t o a s p h e r o i d w i t h an accompanying i n c r e a s e i n s t r e n g t h and d u c t i l i t y .  T h i s change i n g r a p h i t e  shape has been r e l a t e d t o an i n c r e a s e  12 3  i n the g r a p h i t e - m e l t , i n t e r f a c i a l energy ' ' . • I t i s t h e r e l a t i o n s h i p between t h e s u r f a c e energy and the. r e s u l t i n g , g r a p h i t e form which w i l l be examined i n t h i s  thesis.  - 2 -  B..Background Theory  k 1.  .The- S u r f a c e T e n s i o n  The  Parameter  most g e n e r a l approach t o v a r i a t i o n s o f the f r e e energy, of a  homogeneous h u l k phase can be  considered  i n terms of the f o l l o w i n g b a s i c  thermodynamic r e l a t i o n s h i p : dF = - SdT  where  dF S T V P JJL^ n-j_  In a two  is is is is is is is  the the the the the the the  +  VdP  +  <^,M  ±  dn _ j  change i n the. Gibbs f r e e energy entropy a b s o l u t e temperature volume pressure c h e m i c a l p o t e n t i a l o f component i number o f moles o f component i  phase system a s u r f a c e of s e p a r a t i o n w i l l be p r e s e n t  thus an a d d i t i o n a l energy term w i l l be  required.  i s a s s o c i a t e d w i t h the change i n the surroundings  and  T h i s a d d i t i o n a l energy of the s u r f a c e atoms.  A  5 simple  but  d e s c r i p t i v e p i c t u r e of a m e t a l s u r f a c e has been proposed by U h l i g .  It i s considered  t o be a p p o r t i o n o f the l a t t i c e where atoms have fewer t h a n  the u s u a l number o f n e a r e s t n e i g h b o u r s . . The bond must t h e r e f o r e be g r e a t e r .  s t r e n g t h of each i n t e r a t o m i c  S i n c e the s t r e n g t h p e r b o n d . i s  a s s o c i a t e d w i t h the degree of a t t r a c t i o n o f the atoms, the  characteristic  -atomic r a d i u s or the d i s t a n c e o f c l o s e s t approach must be l e s s . restraint  of the p a r e n t  directly  . I t i s the  l a t t i c e t o t h i s tendency f o r c l o s e r approach t h a t  g i v e s r i s e t o what i s c a l l e d s u r f a c e t e n s i o n  (\/ ).  To i n c r e a s e the a r e a of a s u r f a c e by an i n f i n i t e s i m a l amount, . dA, at constant required i s  T, P and ydA.  composition,  these bonds must be  s t r e t c h e d and  the work  Thus the s u r f a c e f r e e energy change can be w r i t t e n :  dF  and a t constant  s  s -S dT  =  s V dP  +  •  +  s  or t h e s u r f a c e  free energy/unit  i n the l i q u i d ,  l e a d i n g t o t h e dimensions o f  a r e a and the s u r f a c e t e n s i o n a r e  l e n g t h or ergs/cm , .i.e., energy/unit  modified  The R e l a t i o n s h i p  ^ b e i n g . dynes/cm, i . e . , f o r c e / u n i t  of S u r f a c e  Energy t o P r e c i p i t a t i n g Form  i s known t h a t n u c l e a t i n g • s h a p e s can be c o n t r o l l e d or a t l e a s t  by v a r i a t i o n s ' i n the i n t e r f a c i a l energy Turnbull  8  and T u r n b u l l and F i s h e r  t h e o r e t i c a l expressions nucleation  identical  area.  2  It  s * d^  T, P and n^  2>  2.  ^ + J>_^-JU  s/ ^ dA  9  6,7  have d e r i v e d the f o l l o w i n g  f o r the r a t e o f homogeneous and  i n the s o l i d i f i c a t i o n o f  arsons  component  heterogeneous  system:  3  I  ..I  and  where  v  •=  K  =  K  S  I  v  y  exp  s  exp  and I  g  [  (  ^  )  2  .  k T  ]  .3 .  -a V f ( Q ) ,  '  k  3  T  a r e the r a t e s of homogeneous and  nucleation respectively,  ^  e  c r y s t a l and t h e p a r e n t l i q u i d ^  i "t n  e r  f a c i a l energy between.the  on the n u c l e u s shape,  a  i s the  constant  f(9) i s a f u n c t i o n o f the e q u i l i b r i u m  angle between the n u c l e u s and the n u c l e a t i n g phase  ft I n most developments .V  solidifying  i s the f r e e energy change p e r u n i t  volume for. the t r a n s i t i o n o f t h e l i q u i d t o the s o l i d , dependent  heterogeneous  ^ 0  ( f o r heterogeneous  contact nucleation),  s i n c e the i n t e r f a c e ' i s assumedplanar.. :  - k -  K  y  and K  s  a r e c o n s t a n t s dependent  on the n u c l e u s shape, s u r f a c e a r e a o f  the c r i t i c a l n u c l e u s , f r e e energy o f a c t i v a t i o n f o r t r a n s p o r t of an atom from the l i q u i d t o the c r y s t a l , temperature of the system, e t c .  These r e l a t i o n s h i p s i l l u s t r a t e the s i g n i f i c a n c e o f the f a c i a l energy w i t h r e s p e c t t o the r a t e o f n u c l e a t i o n . growing n u c l e i i s dependent  inter-  The number o f  on the r a t e o f n u c l e a t i o n which i n t u r n i s  6 a s s o c i a t e d w i t h the degree of u n d e r c o o l i n g  . . I t i s s p e c i f i c a l l y these  two p r o p e r t i e s , t h e number o f growing n u c l e i and the degree of u n d e r c o o l i n g , which may form. changes  a f f e c t the r a t e o f growth and hence t h e shape o f the  solidifying  The i n t e r f a c i a l energy i s thus an important parameter when c o n s i d e r i n g i n t h e shape o f a p r e c i p i t a t i n g  material.  . A l t h o u g h the n u c l e a t i n g form i s c o n t r o l l e d by such  thermodynamic  parameters as t h e i n t e r f a c i a l energy, the f i n a l shape observed i s a l s o dependent  on the growth c o n d i t i o n s f o l l o w i n g  nucleation.  A l t h o u g h the s o l i d - l i q u i d i n t e r f a c i a l energy i s the parameter o f i n t e r e s t , i t s direct:.. time.  e x p e r i m e n t a l d e t e r m i n a t i o n i s not p o s s i b l e a t t h i s  The b e s t approach t o the problem.can o n l y i n d i c a t e t h e d i r e c t i o n  magnitude  o f changes  and  i n . t h e i n t e r f a c i a l energy due t o a d d i t i o n s o f v a r i o u s  elements.  3.  The E f f e c t o f S o l u t e A d d i t i o n s on I n t e r f a c i a l Energy  S o l u t e atoms can change i n t e r f a c i a l e n e r g i e s by p r e f e r e n t i a l l y a d s o r b i n g on the i n t e r f a c e i n q u e s t i o n .  I f the i n t e r a t o m i c f o r c e s a r e such  t h a t the s o l u t e element i s r e j e c t e d . b y t h e m a t r i x atoms, the solute.may become p r e f e r e n t i a l l y c o n c e n t r a t e d a t the s u r f a c e o f the m a t e r i a l - hence the term, s u r f a c e a c t i v e element.  The r e s u l t i n g excess s u r f a c e  concentration  - 5-  would change the s u r f a c e t e n s i o n o f the a l l o y . e x h i b i t a p o s i t i v e d e v i a t i o n from R a o u l t ' s  Thus those  elements t h a t  law should be s u r f a c e a c t i v e  t o v a r y i n g degrees.  The t h e o r e t i c a l approach t o excess s u r f a c e c o n c e n t r a t i o n s the r e s u l t i n g e f f e c t on the i n t e r f a c i a l energy-makes use o f Gibbs  and  Adsorption  10  Theory  . .For a b i n a r y a l l o y t h i s has the g e n e r a l form  where  d.-Y' i s the change i n the' i n t e r f a c i a l energy P i s the excess . i n t e r f a c i a l c o n c e n t r a t i o n o f component i dpi i s the change i n the c h e m i c a l p o t e n t i a l o f component i L  T h i s reduces t o  r* -  -H.  a t a.chosen i n t e r f a c e  p o s i t i o n where the excess c o n c e n t r a t i o n  s o l v e n t atom, i s z e r o .  By r e p l a c i n g , t h e c h e m i c a l p o t e n t i a l jixx by RT I n a^,  the  s i m p l i f i e d form o f the a d s o r p t i o n e q u a t i o n  P  -  : RT  where  a R T  2  3  of the  i s obtained  l n a  2  i s t h e . ^ a c t i v i t y o f component 2 i s the gas c o n s t a n t i s t h e a b s o l u t e temperature  Where t h e s o l u t e obeys Henry's law t h e mole f r a c t i o n may be used i n p l a c e o f the a c t i v i t y ,  fa  i.e.  . where C  2  =  -  Y  C ^ RT £ C 2  2  i s the mole f r a c t i o n of component 2.  - 6 -  Since  i t i s p o s s i b l e t o determine e x p e r i m e n t a l l y the d i r e c t i o n •  and magnitude of change.of the i n t e r f a c i a l energy, i . e . ^ d ^  i t i s also  ;  p o s s i b l e t o determine whether s u r f a c e a d s o r p t i o n i s o c c u r r i n g . conditions present  at the i n t e r f a c e can be examined and  p r o p e r t i e s , , i n t h i s t h e s i s , the p r e c i p i t a t i n g  C.  Thus the  related to  other  form.  • Review of P r e v i o u s Work S i n c e l i t t l e work.has been done i n which s u r f a c e e n e r g i e s  r e l a t e d t o the g r a p h i t e form,. i t i s n e c e s s a r y as separate  parameters.  T h i s s e c t i o n w i l l d e a l f i r s t w i t h the  t e n s i o n d a t a r e p o r t e d f o r Fe-C a l l o y i n g elements, and to  composition  and  t o c o n s i d e r the.two  are initially  surface  a l l o y s , , i n c l u d i n g , the e f f e c t o f v a r i o u s  secondly-with  the g r a p h i t e form and  s o l i d i f i c a t i o n c o n d i t i o n s . . The  i t s relationship  t h i r d and  w i l l review, the data r e p o r t e d i n which g r a p h i t e form and  f i n a l section  s u r f a c e energy  have been r e l a t e d .  1.  Surface.Tension  Measurements  Considerable  i n t e r e s t . h a s r e c e n t l y been d i r e c t e d t o o b t a i n i n g  surface tension values  f o r m a t e r i a l s o f e i t h e r h i g h p u r i t y or p r e c i s e l y  known c o m p o s i t i o n . o f the e a r l y work. to  This, has been n e c e s s i t a t e d by the poor r e p r o d u c i b i l i t y . Q u a n t i t a t i v e l y comparable data i s now  the a p p r e c i a t i o n of the marked e f f e c t of minor c o n c e n t r a t i o n s  active materials. i r o n and  The  due  of,surface  e f f e c t of minor elements i s e s p e c i a l l y important  i t s a l l o y s s i n c e two  of the major contaminants a r e S and  of which are v e r y s u r f a c e a c t i v e . be  obtainable  0,  Only, t h a t data r e c e n t l y r e p o r t e d  c o n s i d e r e d , as good r e p r o d u c i b i l i t y i s a t t a i n e d .  in  both will  - 7  I t has  been shown t h a t the  s u r f a c e t e n s i o n of Fe-C  independent of the carbon c o n c e n t r a t i o n •  -  alloys is  over the range 0 t o 4.5  wt.^  2 ,  ^~^.  13  :  Dyson ^ has  e s t a b l i s h e d t h a t sulphur  of l i q u i d i r o n and p r e d i c t s . 1920  dynes/cm f o r the ^ ^y of  pure i r o n i n agreement w i t h p u b l i s h e d " 2,11,12,14 carbon a l l o y s . A l t h o u g h carbon i s not p r e s e n c e does i n f l u e n c e the  a d d i t i o n s lower the y  values  f o r pure i r o n and  Fe-C-S a l l o y s .  .2 of s e v e r a l i n v e s t i g a t i o n s K e v e r i a n p l o t t e d the sulphur  as shown i n F i g u r e  sulphur-free,  s u r f a c e a c t i v e i n pure Fe-C  y^.of  ^y  iron-  alloys, i t s  To compare the r e s u l t s  ^  versus a c t i v i t y  of  l a . •Although'the e f f e c t of carbon on the S  activity  15 i s not  evident  i n t h i s p l o t , Figure  l b . shows the  data, o f K o z a k e v i t c h  i n a s l i g h t l y , d i f f e r e n t manner c l e a r l y , i l l u s t r a t i n g ' t h e e f f e c t of the - A d d i t i o n s t o i r o n of elements which are not as N i , produce a change.in the f u n c t i o n o f the atomic per  carbon.  s u r f a c e active,.. such  s u r f a c e t e n s i o n of the a l l o y as a  cent  plotted  linear  o f the a l l o y i n g , a d d i t i o n " ^ .  17 Kaufman and Whalen  have r e p o r t e d  a l l o y s h a v i n g a wide range of N i a d d i t i o n s . on the Fe-C  change of  "^  L V  a l l o y s containing No  with Ni a d d i t i o n s . small a d d i t i o n s of  y The  values  f o r t e r n a r y Fe-1.5$>C-Ni  carbon had  l i t t l e effect  A s i m i l a r e f f e c t i s expected f o r Mn.  q u a n t i t a t i v e r e s u l t s have been p u b l i s h e d  concerning  the e f f e c t 18  of Ce has  a d d i t i o n s on the  surface  p r e d i c t e d a decrease i n ^  f a c t t h a t Ce c o n t a i n i n g S,  i s a strong  L  t e n s i o n of pure i r o n . V  sulphide  w i t h a d d i t i o n s o f Ce.  However, M i n k o f f It i s a well  former and w i t h a d d i t i o n s  the p r i m a r y a c t i o n o f the Ce  i s t o remove the  of Ce  established  to iron 2 19 sulphur ' .  - 8 -  0.0001  Figure l a .  0.001  0.01 c. A C T I V I T Y oi S U L F U R  Comparison o f S u r f a c e T e n s i o n Data W i t h Respect t o S A c t i v i t y ( K e v e r i a n )  Effect of Sulfur on the Surface Tension of Liquid Iron-Carbon Alloys at 1450°C (2642°F).  Sulfur,  Figure l b .  w/o  K o z a k e v i t c h ' s ' D a t a Showing the E f f e c t C and S, ( K o z a k e v i t c h ^ )  of  -9 p  Keverian  has shown t h a t a d d i t i o n s o f Ce t o an i r o n c o n t a i n i n g  sulphur  cause an i n c r e a s e i n ^ y . 2. • S o l i d i f i c a t i o n o f a ;.Hypereutectic An  Iron  e x t e n s i v e review., o f the s o l i d i f i c a t i o n and g r a p h i t i z a t i o n  o f c a s t i r o n s has been compiled  by Boyles  •20 PI ,,Morrogh and W i l l i a m s and  22 25 Loper and Heine  >  . -Although  t h i s t h e s i s d e a l s .with t h e simple Fe-C  system i n the h y p e r e u t e c t i c C range c o n t a i n i n g o n l y minor a d d i t i o n s o f S, Ni,-Mn and Ce and not a . c a s t are very  i r o n , the s o l i d i f i c a t i o n  characteristics  similar^. .The'main a d d i t i o n t o t h e Fe-C system t o produce a , c a s t i r o n i s  S i , t h e major e f f e c t o f which i s t o c r e a t e a range over w h i c h t h e e u t e c t i c s o l i d i f i e s and t o s t a b i l i z e t h e g r a p h i t i c form o f carbon.  .Figure 2 . . i l l u s t r a t e s - t h e Fe-C phase diagram and c o n t a i n s the e q u i l i b r i u m , . s o l i d i f i c a t i o n c o n d i t i o n s f o r b o t h t h e g r a p h i t e and the F e C 3  system. • I n c o o l i n g a h y p e r e u t e c t i c l i q u i d below t h e l i q u i d u s p r o e u t e c t i c g r a p h i t e (kis'h g r a p h i t e ) forms i n t h e m e l t . temperature t h i s form w i l l develop  With  temperature  decreasing  and may. f l o a t t o t h e s u r f a c e due t o  , 2k i t s lower s p e c i f i c g r a v i t y  .  A t t h e e u t e c t i c a r r e s t temperature a . e u t e c t i c  of a u s t e n i t e and g r a p h i t e s o l i d i f i e s called a eutectic c e l l . graphite already present.  These c e l l s a r e g e n e r a l l y n u c l e a t e d . b y .The ends o f t h e g r o w i n g , f l a k e  i n c o n t a c t w i t h the s u r r o u n d i n g shown i n the sketches  on a - s p h e r o i d a l c r y s t a l l i z a t i o n  front  the k i s h  g r a p h i t e remain  l i q u i d . . The sequence o f development i s  o f F i g u r e 3.  ATOMIC PERCENT CARBON  - 11 -  ~l  Melt  Kish M  Graphite  with  Kish  Austenite  Graphite  L Above E u t e c t i c A r r e s t  - Figure 3.  J  Eutectic Graphite  with  Austenite  J  J u s t Below. E u t e c t i c A r r e s t  Graphite.Development-Above and Below t h e Eutectic Arrest  On c o m p l e t i o n  of the e u t e c t i c s o l i d i f i c a t i o n the s t r u c t u r e c o n s i s t s  of i r r e g u l a r k i s h g r a p h i t e f l a k e s and s m a l l e r e u t e c t i c f l a k e g r a p h i t e , t h e matrix being a u s t e n i t e .  With decreasing  temperature t o t h e . e u t e c t o i d , the s o l u b i l i t y o f  carbon i n a u s t e n i t e d e c r e a s e s p r o d u c i n g usually, deposited  some p r o e u t e c t o i d g r a p h i t e which i s  on.the f l a k e s a l r e a d y p r e s e n t .  Below t h e e u t e c t o i d temp-  e r a t u r e , the a u s t e n i t e decomposes t o e i t h e r C>(, p l u s g r a p h i t e o r ^ depending on t h e r e l a t i v e s t a b i l i t i e s Fe C transformation 3  low a t - t h e s e  o f the two systems.  plus  Fe C, 3  G e n e r a l l y the  i s predominant as the d i f f u s i o n r a t e o f carbon i s r e l a t i v e l y  temperatures.  No observable  changes occur as t h e s t r u c t u r e i s  c o o l e d t o room, temperature.  I n c r e a s i n g , the c o o l i n g r a t e produces a f i n e r , randomly o r i e n t e d e u t e c t i c g r a p h i t e , type D i n t h e A-.S..T.M. G r a p h i t e  Form  Designation^.  - 12  -  a. E f f e c t s o f A l l o y A d d i t i o n s , on the G r a p h i t e Form i.  Sulphur  Garber  and W i l l i a m s  content t o 0.028 wt..$  i n c r e a s e s the s i z e and. amount o f the p r i m a r y  g r a p h i t e and decreases  the amount of u n d e r c o o l e d  A coarse f l a k e e x i s t e d a t 0.028 up t o 0.1  wt.$>.  have r e p o r t e d t h a t i n c r e a s i n g the  sulphur flake  D-type e u t e c t i c g r a p h i t e .  and p e r s i s t e d as the predominant.form  A t r a n s i t i o n from f l a k e t o mesh t o compact aggregate  to  f r e e c a r b i d e o c c u r r e d w i t h i n c r e a s e i n the s u l p h u r content up t o 0.6 wt.$>.  While o b s e r v i n g the e f f e c t o f S a d d i t i o n s , Garber a l s o noted  a  carbon d e p o s i t on the s u r f a c e of the i n g o t s , i n c r e a s i n g i n amount w i t h i n c r e a s i n g S.  He  i n t e r p r e t e d t h i s e j e c t i o n . o f carbon  b e i n g a s u r f a c e phenomenon i n which g r a p h i t e was  from the melt  not w e t t e d by the  as melt.  20 ..Boyles l i q u i d during-the  has  shown.that s u l p h u r i s c o n c e n t r a t e d i n the  f o r m a t i o n of the p r i m a r y d e n d r i t e s ( h y p o e u t e c t i c i r o n )  and d u r i n g f r e e z i n g of the e u t e c t i c i s f u r t h e r c o n c e n t r a t e d c e l l boundaries. ii.  eutectic  i n the  T h i s s u l p h u r i s f i n a l l y p r e c i p i t a t e d as FeS  eutectic  inclusions..'  .Manganese 27  Williams  has  shown t h a t i n c r e a s i n g the manganese content o f  a l l o y s i n c r e a s e s the tendency f o r the s t r u c t u r e t o s o l i d i f y .111.  T  i n molten i r o n i s lowered  i s i n c r e a s e d , 0.2$> f o r a kfy N i a d d i t i o n .  to  white.  , . . ,28 .Nickel  S o l u b i l i t y of carbon  temperature,  Fe-C  An  as the n i c k e l . c o n t e n t  i n c r e a s e occurs i n t h e  eutectic  25°F f o r a h'jo N i a d d i t i o n , . r e d u c i n g the tendency f o r the. e u t e c t i c  s o l i d i f y w i t h F e C as the s t a b l e phase. 3  - 13  N i c k e l i s r e a d i l y s o l u b l e i n s o l i d i r o n , e n l a r g i n g the c o m p o s i t i o n range i n which a u s t e n i t e o f the  c r i t i c a l transformation  is stable.  -  temperature-  This r e s u l t s i n a lowering  temperature of a u s t e n i t e , . about kO°F f o r '  each <$> N i added.  It  is difficult  e x p l a i n i n g the microstructure;'  cast  to discuss  the e f f e c t s of s p e c i f i c a d d i t i o n s when  i r o n - s t r u c t u r e . . I t s u f f i c e s t o say t h a t the  i s a r e s u l t of the  s p e c i f i c c o m p o s i t i o n and  observed  cooling rate  of  the a l l o y .  b.  . E f f e c t of C o o l i n g Rate on  Structure  29 Morrogh  has  g r a p h i c a l l y i l l u s t r a t e d the e f f e c t - o f c o o l i n g  r a t e on.the r e l a t i v e s t a b i l i t y o f the a u s t e n i t e - g r a p h i t e , transformation  (Figure  C O O L I N G  'p  -  Temperature of solidification of white iron  R A T E  k. R e l a t i v e S t a b i l i t i e s , o f the G r a p h i t e and By the C o o l i n g Rate (Morrog  - W i t h i n c r e a s i n g c o o l i n g r a t e s the e u t e c t i c forms becomes p r o g r e s s i v e l y lower.  whereas below  -T , 2  C a r b i d e as  Affected  temperature a t which the k, 1  In F i g u r e  t o the e q u i l i b r i u m c o o l i n g c o n d i t i o n s below which the occurs,  3  h).  Below this temperature white iron . can solidify  Figure  austenite-Fe C  t h i s b e i n g the m e l t i n g  X  graphite  corresponds  y -graphite.transition  point  of the white i r o n  - Ik -  e u t e c t i c , the  ^ - F e C w i l l predominate. . I n c r e a s i n g the c o o l i n g , r a t e 3  causes the e u t e c t i c t r a n s i t i o n temperature t o f o l l o w a-curve of form At a c o o l i n g r a t e and t r a n s f o r m a t i o n temperature e q u a l t o W,  white  XU.  iron  w i l l be the e u t e c t i c second component.• . With a f u r t h e r i n c r e a s e i n the c o o l i n g r a t e the e u t e c t i c s o l i d i f i c a t i o n temperature decreases s l i g h t l y according to  WZ.  The tendency f o r an i r o n t o s o l i d i f y white i s a l s o a f f e c t e d by the c o m p o s i t i o n - S i and Mn  increase.: t h i s tendency w h i l e N i decreases i t .  In a d d i t i o n , s u p e r h e a t i n g w i l l cause a melt t o u n d e r c o o l t h e r e b y i n c r e a s i n g the F e C 3  stability.  3.  S o l i d i f i c a t i o n o f a H y p e r e u t e c t i c Nodular I r o n  S i n c e no i n f o r m a t i o n i s a v a i l a b l e on the e f f e c t o f a d d i n g Ce t o a pure Fe-C a l l o y , i t i s n e c e s s a r y t o r e s t r i c t Fe-C^Si a l l o y .  our d i s c u s s i o n t o an  ..When Ce i s added t o such a m e l t , s m a l l g r a p h i t e  nuclei  appear above the l i q u i d u s temperature, t h e i r p r e s e n c e h a v i n g been e s t a b l i s h e d  22 2^5 ^50 ^51 by r a p i d quenching t e s t s  '  '  '  . ..These n u c l e i have o n l y been observed  i n i r o n s i n which the g r a p h i t e p r e c i p i t a t e s i n the s p h e r o i d a l form. and Heine  c  .Loper  have developed a schematic r e p r e s e n t a t i o n o f the temperature  range o f n u c l e a t i o n and growth f o r the v a r i o u s g r a p h i t e forms  (Figure  5).  • W i t h d e c r e a s i n g temperature the n u c l e i develop i n t o l a r g e r s p h e r o i d s . These are s e p a r a t e d from the l i q u i d by a t h i n s h e l l o f a u s t e n i t e .  The  i i i i c k n e s s o f t h i s s h e l l remains c o n s t a n t up t o the e u t e c t i c s t a r t temperature a l t h o u g h the nodules grow i n s i z e .  Over the e u t e c t i c s o l i d i f i c a t i o n  range  the nodule s i z e c o n t i n u e s t o i n c r e a s e as does the s u r r o u n d i n g a u s t e n i t i c  shell.  ,  - 15 GROWTH TEMPERATURE RANGE  t  2000  SPHEROIDS J f L A K E SHAPES FILM, LACY, COMPACT 1500  20 PE«CINT  F i g u r e 5-  JO  40  CARBON  . N u c l e a t i o n Range of the V a r i o u s G r a p h i t e (Loper and H e i n e ^ )  Forms  2  For growth o f the nodule t o c o n t i n u e , s h e l l and  i r o n must d i f f u s e  carbon must d i f f u s e t h r o u g h the  i n the o p p o s i t e d i r e c t i o n .  With i n c r e a s i n g  s h e l l t h i c k n e s s the d i f f u s i o n time i n c r e a s e s , impeding growth. force necessary  The  driving  f o r the r e a c t i o n t o p r o c e e d i s s u p p l i e d by a decrease i n the  temperature. . Such a s o l i d i f i c a t i o n p r o c e s s s o l i d i f i c a t i o n - r a n g e , being approximately  .  austenite  requires a greater eutectic  twice t h a t f o r a comparable  grey  22  iron •Although some nodules remain dormant d u r i n g the e u t e c t i c s o l i d i f i c a t i o n no  s a t i s f a c t o r y e x p l a n a t i o n has been developed t o e x p l a i n t h i s  e f f e c t . - Subsequent c o o l i n g below.the e u t e c t i c t o the e u t e c t o i d g e n e r a l l y r e s u l t s i n p r e c i p i t a t i o n of the excess carbon on t h e g r a p h i t e I t has  o f t e n been r e p o r t e d t h a t s u p e r c o o l i n g i s a requirement f o r  1 the f o r m a t i o n  of spheroidal graphite  j ' .  However, i n the experiments p r e v i o u s l y  d i s c u s s e d , the g r a p h i t e nodules were p r e s e n t temperature and  present.  above the e u t e c t i c s o l i d i f i c a t i o n  thus were not a s s o c i a t e d w i t h s u p e r c o o l i n g .  the e u t e c t i c s o l i d i f i c a t i o n range i s a r e s u l t i f i c a t i o n i n the s p h e r o i d a l form.  o f and  The widening of  not the cause of  solid-  - 16  Morrogh 32  has  i l l u s t r a t e d the development c h a r a c t e r i s t i c s o f  a nodule, as shown i n F i g u r e  F i g u r e 6.  6.  Growth C h a r a c t e r i s t i c s of a G r a p h i t e  (Morroglr  The  -  Nodule  )  nodule i s e s s e n t i a l l y a r a d i a l development of the b a s a l p l a n e of  the  33 hexagonal g r a p h i t e  .  k.  R e l a t i o n s h i p Between I n t e r f a c i a l Energy and G r a p h i t e  The  change from the f l a k e t o the  t o an i n c r e a s e i n the g r a p h i t e - m e l t  Form  s p h e r o i d a l form has been r e l a t e d  i n t e r f a c i a l energy  2,3,18  .  I t i s thought  t h a t such an i n c r e a s e would n e c e s s i t a t e a h i g h e r d r i v i n g f o r c e f o r  solidifi-  p  c a t i o n t o occur, a c t i n g as a b a r r i e r t o n u c l e a t i o n . Ce  Keverian  a d d i t i o n s t o an Fe-C-S a l l o y i n c r e a s e d the s u r f a c e t e n s i o n ,  the d e s u l p h u r i z i n g power of Ce. graphite-melt  However no a s s o c i a t e d i n c r e a s e  i n t e r f a c i a l energy c o u l d be  eutectic  reflecting i n the  determined.  Such an approach i m p l i e s t h a t n o d u l a r g r a p h i t e supercooling.  showed t h a t  i s related to  T h i s c o u l d not account f o r the presence o f n u c l e i above the  temperature.  - 17  •D.  -  S e s s i l e Drop Technique I t i s obvious t h a t i f one wishes t o - e s t a b l i s h the i n t e r f a c e  conditions present  d u r i n g g r a p h i t i z a t l o n , one  must examine the  graphite-  melt i n t e r f a c e . • However, i t i s not p o s s i b l e t o measure d i r e c t l y s u r f a c e energy o f such an i n t e r f a c e . one  Using.the techniques  the  available  i s a b l e , at b e s t , t o determine the d i r e c t i o n and magnitude of change  of t h i s parameter.  The  approach used i n t h i s work i s r e l a t e d t o the shape of a  l i q u i d drop r e s t i n g . o n an i n e r t base p l a t e . drop t e c h n i q u e  y and  and  and p e r m i t s  T h i s i s known as the  sessile  e v a l u a t i o n of the s u r f a c e t e n s i o n o f the  the c o n t a c t angle  t h r o u g h the  dropj0.  The  experimental  liquid,  difficulties  e r r o r s i n h e r e n t i n t h i s approach a r e o u t l i n e d i n Appendix I .  The  shape of" a l i q u i d drop on a h o r i z o n t a l , i n e r t s u r f a c e i s  determined by the b a l a n c e  between the s u r f a c e t e n s i o n which attempts t o  c r e a t e a s p h e r i c a l drop, i . e . , the lowest  s u r f a c e a r e a / u n i t volume, and  the  g r a v i t a t i o n a l f o r c e which t r i e s t o lower the p o t e n t i a l energy o f the mass by f l a t t e n i n g the. l i q u i d .  The  equation  of the s e c t i o n a l o u t l i n e o f such a drop i s a second  o r d e r d i f f e r e n t i a l which has been n u m e r i c a l l y s o l v e d t o f o u r p l a c e s d e c i m a l by B a s h f o r t h and Adams-^. i s p o s s i b l e t o determine Y ^ y  It i s necessary i n Figure 7.  a n (  ^  ^  e  of t h e i r t a b u l a t e d s o l u t i o n s i t  c o r r t a c  "t  angle  0.  t o measure the parameters x, x , 1  1  z , z  1  shown  From these parameters and B a s h f o r t h and'Adams' t a b l e s ,  f u r t h e r parameters, jit and b can be  35 D. J . Rose  By use  of  ) from which  o b t a i n e d (as shown i n the t h e s i s of  two  F i g u r e 7-  The S e s s i l e Drop Parameters o f I n t e r e s t and 0 D e t e r m i n a t i o n LV  Y  For  - 19 Y  and 0, YIN  a  =  a  LV  where  g d m  g d b  /5  2  m2  i s the g r a v i t y c o n s t a n t i s the d e n s i t y i s the m a g n i f i c a t i o n o f the drop.from.which parameters were taken  the i n t e r i o r c o n t a c t a n g l e , can be determined. *id.0 can be measured as independent parameters  i n t h i s experimental procedure.  the  The f a c t t h a t b o t h is. a d i s t i n c t  advantage  By a p p l y i n g the v a l u e s o b t a i n e d f o r y ^ y  and 0, and changes i n - t h e s e v a l u e s , t o Young's E q u a t i o n ,  Y..LS  =  Y  - V"  *SV  cos  0  "LV  t h i s b e i n g a b a l a n c e of the h o r i z o n t a l components o f the s u r f a c e shown i n F i g u r e 8^ assumptions be  for  and by.having a knowledge of,, or by making c e r t a i n  ^ gy, the d i r e c t i o n and magnitude of change o f  YsL  c  a  n  determined.  E.  C h o i c e . o f System and Aim o f I n v e s t i g a t i o n The complexity- o f commercial  any, fundamental it  forces  investigation.  c a s t i r o n s " r e s t r i c t s t h e i r use i n  To reduce the many c o m p o s i t i o n v a r i a b l e s  i s n e c e s s a r y t o examine simple b i n a r y , . o r a t most, t e r n a r y a l l o y s .  To  study g r a p h i t i z a t i o n t h e r e f o r e , the pure Fe-C b i n a r y i s the obvious c h o i c e . However, as t h i s system may  c o n t a i n the m e t a s t a b l e c a r b i d e i t i s a l s o  n e c e s s a r y t o employ c o n d i t i o n s which ensure the s t a b i l i t y o f the g r a p h i t e form.  T h i s was  accomplished by. a i r c o o l i n g the carbon  puron i r o n i n a reduced p r e s s u r e o f 10  5  mm  free saturated  Hg.  S i n c e changes i n the p r i m a r y g r a p h i t e shape were t o be  related  t o the g r a p h i t e - m e l t i n t e r f a c i a l energy p r e s e n t d u r i n g g r a p h i t i z a t i o n , i t was  n e c e s s a r y t o maximize•these  changes t o ensure t h e i r d e t e c t i o n .  t r a n s i t i o n from the f l a k e t o the n o d u l a r form was  thus examined.  The  - 2 0  -  -•It has been reported, t h a t a nodule occurs a t an e a r l y stage i n i t s growth i n c o n t a c t w i t h the melt, and i s a r a d i a l development o f the b a s a l plane  o f the hexagonal g r a p h i t e  i n t e r f a c i a l conditions present g r a p h i t e b a s a l plane-melt  system. - Thus, t o determine t h e  during the formation  o f a nodule, the  i n t e r f a c e had t o be i n c l u d e d i n the system under  investigation.  P y r o l y t i c graphite  i s composed o f p a r a l l e l ,  misoriented-layers  36 of the g r a p h i t e b a s a l plane-'  .  Thus by m e l t i n g Fe-C b i n a r y a l l o y s on a  p y r o l y t i c graphite p l a t e the melt-graphite be  studied.  b a s a l plane  i n t e r f a c e could  To ensure t h a t no r e a c t i o n o c c u r r e d a t t h i s  complying w i t h those  conditions necessary  the Fe-C a l l o y s were carbon s a t u r a t e d .  i n t e r f a c e •y  f o r the s e s s i l e drop a p p l i c a t i o n ,  I n a d d i t i o n , s i n c e i t was  necessary  that t h e energy parameters be o b t a i n e d d u r i n g g r a p h i t i z a t i o n , t h e a l l o y had to c o n t a i n a g r e a t e r amount o f carbon t h a n t h a t r e q u i r e d f o r s a t u r a t i o n a t the m e l t i n g temperature. at  1500°C  Thus, t h e b i n a r y Fe-C a l l o y was s a t u r a t e d w i t h C  and quenched from t h i s temperature t o r e t a i n t h e carbon  content.  S i n c e i t i s o n l y p o s s i b l e t o determine t h e d i r e c t i o n and magnitude o f change o f t h e s o l i d - l i q u i d i n t e r f a c i a l energy i t was n e c e s s a r y s o l u t e a d d i t i o n s t o the b a s i c a l l o y . chosen f o r t h e f o l l o w i n g  t o make  .The elements Ce,- S, N i and Mn were  reasons:  .- Ce was employed as t h e s p h e r o i d i z i n g agent t o e f f e c t t h e change from t h e f l a k e t o t h e n o d u l a r  form.  - Sulphur a d d i t i o n s were made s i n c e the presence o f , or r a t h e r the removal o f s u l p h u r has been a s s o c i a t e d w i t h nodule  formation.  - N i c k e l and manganese were used, because b o t h a r e s u l p h i d e although  much weaker t h a n Ce, and b o t h a r e g e n e r a l l y p r e s e n t  cast^ i r o n s .  formers,  i n commercial  - 21 -  The o r i g i n a l p l a n was t o s t u d y the e f f e c t  of sulphur  additions  and a d d i t i o n s o f s u l p h u r p l u s Ce, N i o r Mn on the s u r f a c e energy and graphite  form.  However, p r e l i m i n a r y experiments i n d i c a t e d t h a t t h e  examination o f a d d i t i o n s o f the s i n g l e elements t o the Fe-C system would be more p r o f i t a b l e .  - 22 II.  EXPERIMENTAL ^ . • M a t e r i a l s Used S e s s i l e drop experiment were conducted, u s i n g  carbon-saturated  puron i r o n as t h e b a s i c a l l o y , Ce, S, N i and Mn as a d d i t i o n agents, and p y r o l y t i c g r a p h i t e as t h e base p l a t e .  The spectrographic  Fe-C a l l o y was p r e p a r e d  by i n d u c t i o n h e a t i n g puron i r o n , i n a  grade g r a p h i t e c r u c i b l e t o 1500°C i n a vacuum o f 1 0 "  T h i s temperature was h e l d f o r 10 minutes t o ensure completion r e a c t i o n , t h e power was shut  mm  5  Hg.  of the  o f f and the sample was a l l o w e d t o c o o l .  C r u c i b l e s 0.25" X 0 . 2 0 " were machined from t h i s a l l o y , t h e bottom s u r f a c e b e i n g b e v e l l e d t o ensure an a d v a n c i n g i n t e r f a c e upon m e l t i n g , and  the center being d r i l l e d t o hold a l l o y a d d i t i o n s .  0.5  gms were o b t a i n e d by t h i s p r o c e d u r e .  Master a l l o y s were p r e p a r e d N i and Mn master a l l o y s were p r e p a r e d puron i r o n and melted under 10~  5  Drops o f  approximately  t o ensure b e t t e r c o n t r o l o f t h e a d d i t i v e s . from 99-9$ metals,, these b e i n g added t o  mm p r e s s u r e  i n spectrographic  grade g r a p h i t e  crucibles. The  Ce master a l l o y was p r e p a r e d  u s i n g 99-9$ Ce and puron i r o n , t h e  m e l t i n g b e i n g c a r r i e d out i n a s e a l e d s p e c t r o g r a p h i c under s i m i l a r vacuum c o n d i t i o n s . puron i r o n i n a s p e c t r o g r a p h i c flow  grade c r u c i b l e ,  The S master a l l o y was p r e p a r e d  held  by h e a t i n g  grade g r a p h i t e c r u c i b l e t o 1050°C under a  of H S. 2  The  analyses  o f t h e m a t e r i a l s used and the master a l l o y s  prepared  are r e p o r t e d i n T a b l e I . P y r o l y t i c g r a p h i t e base p l a t e s 5/8" X 5/8" were c u t f r o m - 3 / l 6 X k X 5" sheets  s u p p l i e d by the G e n e r a l E l e c t r i c  Laboratories.  D e t a i l s con-  c e r n i n g t h e p r o d u c t i o n and p r o p e r t i e s o f p y r o l y t i c g r a p h i t e a r e r e c o r d e d i n Appendix I I .  TABLE I . A n a l y s e s o f M a t e r i a l s Used and A l l o y s P r e p a r e d M a t e r i a l or Alloy Faron I r o n ft  Al 0.005  .Cr 0.0008  0.0005 <0.0001  Cu <0.002 0.0004  Ce N.D. <0.02  Fe  Mg  Mn  Mo  .Si  Ti  V  <0.004 <^0.001  0.0005  0.002  0.068<0.01  0.0008  0.0003  0.002  0.001  0.082 ( 0 . 0 1  0.00005^0.0005 0.0008 0.0002  0.0009.  0.005  0.002 M a t r i x ^ 0 . 0 1  - M a t r i x <6.0008 <0.002 <0.002 Matrix  Ni  0.0001 <0.0005 0.001  C  S  Spectrograph!'c Grade G r a p h i t e used f o r molds f o r p r e p a r i n g a l l o y s : 0.0005 <0.0001  0.0004 < 0 . 0 2  Alloy 1  0.0002^0.0001  0.0008  <"0.02  Matrix  0.0002 <0.0005 0.001  0.0008  0.0003  0.003  0.001  5-4  < 0.01  Fe-C A l l o y 4  0.0002<0.0001  0.0006  <'0.02  Matrix  0.0001  0.002  0.03  0.02  0.002  0.002  5.49  <0.01  O.OOOJ^O.0001  0.001  <0.02  Matrix  0.0003 <Co.0005 0.002  0.01  0.01  0.003  0.001.  5-57  <0.Q1  Fe-C  Fe-C  Alloy 5  0.1  Master A l l o y s Fe-S Fe-C-Ce Fe-C -Mn Fe-C-M Pyrolytic Graphite  ft  (0.0005  42.3 5,7 5.25 5.20  18.0 IO.87 0.0008<p.0001  0.0008  0.00005 0.0001  <0.0005<(0.002  0.0002  0.0005  0-53 0.034  0.00005 ^0.0005 M a t r i x 0.01  A n a l y s i s s u p p l i e d w i t h m a t e r i a l , o t h e r s b e i n g o b t a i n e d from Coast E l d r i d g e E n g i n e e r s . not l i s t e d were u n d e t e c t e d .  A l l metallics  ro 1  - 2k B.  Apparatus The  s e s s i l e drop experiments were conducted  i n the i n d u c t i o n •'  apparatus d e s c r i b e d i n d e t a i l i n a t h e s i s by D. J . R o s e ^ . s u s c e p t o r 5/8" X 0.005" X 3" was v y c o r tube.  The  suspended  A molybdenum  i n the c e n t e r o f a 65 mm  O.D.  samples were p l a c e d i n the c e n t e r o f the s u s c e p t o r , no  r a d i a t i o n s h i e l d s b e i n g r e q u i r e d . - A L e p e l (Model T - 1 0 - 3 ) h i g h - f r e q u e n c y i n d u c t i o n g e n e r a t o r s u p p l i e d the power t o the f u r n a c e and temperatures measured a t ^5° t o the f u r n a c e a x i s . f i l a m e n t o p t i c a l pyrometer  was  were  A Hartmann and Braun d i s a p p e a r i n g  employed, the r e a d i n g s b e i n g t a k e n t h r o u g h  a m i r r o r which c o u l d be r o t a t e d i n t o p o s i t i o n between the end o f the f u r n a c e and the p h o t o g r a p h i n g l e n s .  By comparing  these temperatures w i t h v a l u e s  s i m u l t a n e o u s l y o b t a i n e d u s i n g a W-WRe thermocouple c o r r e c t i o n o f + 55°  g r a p h i t e sample a temperature temperature  range  mm  drop shape was  Hg was  s  observed over the  m a i n t a i n e d f o r a l l o f the  tests.  r e c o r d e d u s i n g a. B e l l and Howell 8 mm  camera combined w i t h a l e n s assembly complete  w a  i n t o the p y r o l y t i c  of i n t e r e s t .  A vacuum o f 10  The  fitted  which p e r m i t t e d photographing  movie the  image a t the f i l m s i z e and a t a d i s t a n c e o f about 2 l / 2 f e e t .  apparatus including the v e r t i c a l c o i l employed t o prepare the master  alloys  i s shown i n F i g u r e 9-  C.  Experimental.Procedure Experiments  o f 20 minutes  o f time a f t e r m e l t i n g , temperature  a n  d  d u r a t i o n were conducted,  the  effect  and a l l o y a d d i t i o n b e i n g r e c o r d e d .  c o n t a c t angle d a t a were o b t a i n e d from p r i n t s o f the  p r o j e c t e d images m a g n i f i e d a p p r o x i m a t e l y  10.times.  The  - 25  F i g u r e 9.  Equipment Used f o r A l l o y P r e p a r a t i o n and S e s s i l e Drop Experiments  -  26  The solidified with  graphite  form was o b t a i n e d  -  from p o l i s h e d s e c t i o n s o f .the  drops - the samples were mounted i n 828 epon and p o l i s h e d  6 fi. and 1 p. diamond p a s t e .  Much care was e x e r c i z e d i n h a n d l i n g contamination. concentrated  the m a t e r i a l s t o  avoid  The base p l a t e s were r i n s e d i n acetone, dipped i n t o  HC1, washed, i n a l c o h o l and d r i e d j u s t p r i o r t o t h e i r u s e .  D u r i n g and a f t e r washing, a l l m a t e r i a l s were handled by m e t a l tweezers. A s i m i l a r c l e a n i n g c y c l e was f o l l o w e d f o r the i r o n c r u c i b l e s .  When a d d i t i o n s were made, the m a t e r i a l was p l a c e d f o l l o w i n g the c l e a n i n g - s c h e d u l e , recorded,  t h e c r u c i b l e diameter and weight was  t h e m a t e r i a l s then b e i n g p l a c e d  When a vacuum of 1 ji was o b t a i n e d , determination was repeated A pressure  i n the c r u c i b l e  i n the experimental  apparatus.  a p i c t u r e was t a k e n f o r m a g n i f i c a t i o n  and hydrogen gas was i n t r o d u c e d  t o the system. . T h i s f l u s h i n g  s e v e r a l times t o ensure the removal o f any gaseous contaminants.  o f 500 mm  o f Hg was f i n a l l y h e l d and the m a t e r i a l s were heated  t o r e d heat,, t h e ensuing hydrogen f l a s h i n g removing the s u r f a c e o x i d e s . system was t h e n pumped down t o 10~  5  mm Hg and the temperature was  i n c r e a s e d t o t h e m e l t i n g p o i n t o f the a l l o y taken at t h e . s t a r t . o f melting the time b e i n g  recorded.  (fc£ 1280°C).  cycle,  • A l l samples were quenched from l600°to ensure  Analyses of the s o l i d i f i e d any  slowly  Photographs were  and p e r i o d i c a l l y , t h r o u g h the h e a t i n g  s i m i l a r c o o l i n g c o n d i t i o n s and hence comparable  microstructures.  drops were o b t a i n e d  The  t o guard a g a i n s t  s e r i o u s c o n t a m i n a t i o n s o c c u r r i n g d u r i n g the experiment.  - 27  III.  -  RESULTS •A.  S e s s i l e Drop R e s u l t s . 1.. B a s i c Iron-Carbon  Alloy  1  ... The parameters x, z, x  x  and z  were o b t a i n e d from the  enlarged  n e g a t i v e s and the s u r f a c e t e n s i o n s and c o n t a c t a n g l e s were determined, r e s u l t s being l i s t e d i n Appendix-III.  D e n s i t y v a l u e s were o b t a i n e d  the  by  38 c o n s i d e r i n g the drop t o be  >C s a t u r a t e d a t each temperature  r e p o r t e d r e l a t i o n s h i p between temperature, The average  and  and u s i n g the  d e n s i t y and carbon  c o n t a c t angle f o r the Fe-C  39  concentration  a l l o y - i s • s h o w n i n Table I I .  An e s t i m a t i o n of the s t a n d a r d d e v i a t i o n - f o r t h r e e t e s t s i s a l s o i n c l u d e d t o i l l u s t r a t e the range of r e s u l t s i n any. one t e s t , the c a l c u l a t i o n s i n c l u d e d i n Appendix The  being  IV.  e f f e c t of time and temperature on the c o n t a c t angle i s  i l l u s t r a t e d . i n F i g u r e 10.  Only those 0 v a l u e s f o r temperatures  less  1345°C are p l o t t e d s i n c e above t h i s temperature s i g n i f i c a n t w e t t i n g  than of  the base o c c u r r e d , as shown i n the photographs i n c l u d e d i n F i g u r e 10. the c o n t a c t a n g l e approaches 90° the d e s i r e d z parameter. angle drops f o r t h i s  As  i t becomes v i r t u a l l y , i m p o s s i b l e t o o b t a i n  S u r f a c e t e n s i o n s were o n l y determined  from h i g h  reason, the e q u i l i b r i u m angle f o r temperatures  up  to  1345°C b e i n g s u f f i c i e n t t o p e r m i t the parameter measurement. No c o n s i s t e n t v a r i a t i o n o f was  Yjjj-  w i t h time  or c o n t a c t angle  observed,-the. d a t a b e i n g a v a i l a b l e i n Appendix I I I .  Table I I I i l l u s t r a t e s the pronounced e f f e c t o f ± 0.01" i n the z parameter on the r e s u l t i n g F i g u r e 11.  variation  "Y^y  shows the w e t t i n g c h a r a c t e r i s t i c s of puron i r o n a t  l +15°C as compared t o carbon i  change  s a t u r a t e d puron i r o n a t 1400° and  l600°C.  - 28 TABLE.II. Average S u r f a c e T e n s i o n and. C o n t a c t Angle o f t h e Fe-C, • Fe-C-Ni and Fe-C-Mn A l l o y s Exp. No.  ± 1 <T  Average o'r.v (dynes/cm)  Fe-C A l l o y s 14 19 20 a) S t a t i s tical .b). E f f e c t of Time 27 28 29 35  1163 1074 1079  No.. of Calculations Averaged  150 116 120  Temp. °C  Approx. Equilibrium Angle  29 26 20  1325 1325 1280  126 128  1064  10  1280  -  1206  5 4 4  1290 1335 1345  7  1335  132 122 129 12'9  1197 1234 1116 II52  Average  Max. 957 t o Spread 1307  105  -  1290 t o 1345  128  Fe-C-Ni A l l o y (O.85 wt...# N i ) 1135 . ^5  8  1285  118  Fe-C-Mn A l l o y ( I . 6 5 wt.# Ma) 1261  8  1330  127  .TABLE I I I . E f f e c t o f * 0 . 0 1 " V a r i a t i o n i n the  x and z Parameters on  e.g.. Seq 1^380 o f Experiment 20 x  z + 0.01" z - 0.01"  I.O65 I.O65 I.O65  z  x/z  O.977 O.987 O.967  1.090 1.079 1.101  ^LV (dynes/cm) 1021 1153 900  V LV Variation _  + 132 - 121  - 30 -  F i g u r e 11.  2.  W e t t i n g C h a r a c t e r i s t i c s o f a) Fe-C a t l600°C 0^90° ( l e f t ) b) Fe-C a t l400°C Q ~ 1 1 5 ° c) Puron i r o n a t l 4 l 5 ° C 0 C=75° ( r i g h t )  E f f e c t o f N i and Mn A d d i t i o n s A l t h o u g h separate  and  N i and Mn a d d i t i o n s were made, 0 t o 0.85$> Ni  0 t o I . 6 5 wt.$ Mn, no s i g n i f i c a n t  changes i n V  d a t a p e r t a i n i n g t o the maximum a d d i t i o n s b e i n g  of"0 were noted, t h e  reported  i n F i g u r e 10 and  Table I I .  3.  Effect The  these a l l o y s .  o f Sulphur A d d i t i o n s  s u r f a c e t e n s i o n and c o n t a c t angle were d i f f i c u l t  to obtain f o r  With the a d d i t i o n o f s u l p h u r , t h e s o l u b i l i t y o f g r a p h i t e i n  i r o n i s decreased.  The excess g r a p h i t e was p r e c i p i t a t e d out on t h e s u r f a c e  o f the drop t h e r e b y d i s t o r t i n g the t r u e drop parameters.  A l t h o u g h i t was  known t h a t s u l p h u r had t h i s e f f e c t on carbon i t was thought  t h a t the excess  g r a p h i t e would p r e c i p i t a t e onto the p r i m a r y g r a p h i t e p r e s e n t w i t h i n t h e structure.  F i g u r e 12 i l l u s t r a t e s the e f f e c t o f s u l p h u r on the drop s i l h o u e t t e ,  p l a t e c) showing t h e s e c t i o n e d drop and the a c t u a l drop parameters as compared t o t h e g r a p h i t e  outline  noted i n p l a t e b ) .  I n t h i s case parameter  measurements were t a k e n from t h e s o l i d i f i e d drop and an t e n s i o n was c a l c u l a t e d .  approximate  surface  T h i s s u r f a c e g r a p h i t e p r e c i p i t a t i o n i s no doubt t h e  same carbon d e p o s i t i o n n o t e d by G a r b e r ^ i n h i s s u l p h u r  experiments.  - 31 -  F i g u r e 12.  E f f e c t o f S u l p h u r on Drop S i l h o u e t t e  - Experiment 12  a) A t m e l t i n g b) A f t e r carbon p r e c i p i t a t i o n c) Same sample s e c t i o n e d t o show o u t l i n e o f drop w i t h respect to surface g r a p h i t e .  D i f f i c u l t y was a l s o e x p e r i e n c e d i n g e t t i n g the s u l p h u r i n t o s o l u t i o n i n the b a s i c Fe-C a l l o y b e f o r e v a p o r i z a t i o n of the FeS master a l l o y , p a r t i a l pressure  of a l l s u l p h u r forms over FeS a t  No b a s a l a t t a c k i . e . a d h e r e n c e ?  cf  660°C b e i n g O.58 atmospheres-^7,  the drop t o the p l a t e ,  noted f o r those a l l o y s which e x h i b i t e d s u r f a c e  the  was  graphite p r e c i p i t a t i o n .  T h i s e f f e c t was used t o determine whether s u l p h u r had been d i s s o l v e d i n t o the Fe-C a l l o y , and ^  c a l c u l a t i o n s were o n l y made on those t e s t s which  showed no b a s a l a t t a c k .  T a b l e IV c o n t a i n s the V  which o b v i o u s l y c o n t a i n e d some s u l p h u r .  The t a b l e  values f o r four tests i n c l u d e s the amount o f  s u l p h u r added, the p e r cent s u l p h u r a n a l y s e d i n the d r o p , the c o n t a c t a n g l e , and the average p r o p e r t i e s  of the Fe-C a l l o y .  S i n c e i t was not p o s s i b l e  reproduce a g i v e n s u l p h u r c o n c e n t r a t i o n and s i n c e s u l p h u r contents  of  to  less  than 0.01 wt.$> c o u l d not be a n a l y s e d the v a l u e s cannot be q u a n t i t a t i v e l y compared t o K e v e r i a n ' s d a t a .  However, a decrease i n ^ j ^ y  a n  d an  increase  i n 0 w i t h i n c r e a s i n g sulphur i s observed, consistent w i t h K e v e r i a n ' s f i n d i n g s .  - 32 -  TABLE IV. Effect  V  o f S u l p h u r A d d i t i o n s on  and C o n t a c t A n g l e .  • LV  Experiment Number  wt.ft S added  12  1.86  36  0.30  <b.oi  38  0.01  <0.01  39  0.035  <0.01  891  145  -  <0.01  1152  128  Average Data  Pe-C  4.  Effect  Equilibrium  Average  wt.# S analysed  4  ^LV  0.022  165  338 ( o n l y an approximat i on)  141  801  152  1115  o f Ce A d d i t i o n s '  Upon m e l t i n g the c r u c i b l e c o n t a i n i n g the Ce a l l o y a d d i t i o n , s o l u t i o n o f the a d d i t i o n d i d not o c c u r .  I n s t e a d some p o r t i o n o f i t . f l o a t e d  on the apex o f the molten drop, i t s s i z e d e c r e a s i n g w i t h temperature.  complete  S i l h o u e t t e s from Experiment 31  show the e f f e c t o f i n c r e a s i n g temperature.  a  r  e  increasing  i n c l u d e d i n F i g u r e 13  and  This surface material acts  as an a d d i t i o n a l f o r c e t e n d i n g t o f l a t t e n the drop hence changing  the^^y  observed. . L i t t l e change was  noted i n the c o n t a c t a n g l e w i t h i n c r e a s i n g  temperatures up t o l600°C,•Figure lk. it  was  p o s s i b l e t o determine  extraneous s u r f a c e f o r c e was  To check the e f f e c t 0.04  maintained,  s u r f a c e t e n s i o n s a t the h i g h e r temperature where minimized.  1  The r e s u l t s are r e p o r t e d i n T a b l e V.  o f the extraneous force.; a drop t o which  wt.$> Ce had been added was  T h i s same drop was  Because a h i g h a n g l e was  melted and the shape parameters  recorded.  taken from t h e system, the s u r f a c e d e p o s i t was  removed  - - 3 4  Legend:. Experiment  3  1  Experiment  3  2  (0.01#Ce)-©-  Experiment  3  3  (0.005'/ Ce  145  -  (0.05#Ce)  ) - Q -  0  140 bo  4  1  -p |  o  X.  H  3  5  X  ISO  o  {  X  ° 125  \%oo  —1300 I  Temperature  Figure 14.  IQ  1600  (°C)  C o n t a c t Angle Versus Temperature  f o r Ce T e s t s  TABLE V. - Effect  o f Ce A d d i t i o n s on V LV  and 0  Q  Exp. No.  3  0  3  1  5  2  wt.$ Ce Added  0  0  .  .  0  0  0.01  0  .  0  0  48  0  .  0  5  5  0  0.04  5  1  3  3  5  0  .  0  <  5  -  1  6  2  0  6  1  1  140  5  1  3  0  5  -  1  6  3  0  8  1  3  1  3  8  2  1  5  2  0  -  1  6  4  5  7  5  4  1  3  7  5  1  3  1  5  -  1  6  5  0  8 7 6 , .  1  3  8  1  3  0  5  -  1  4  0  5  864  1  5  6  1  3  6  4  1  3  9  0  2  0  .  0  0  LV  4  .  .  y  0  .  0  3  0  .  0  5  "bottom top  not a n a l y s e d  I6O5  5  5  7  0 . 0 5  1  6  7  0  0  .  0  0  4  0  0  Average  1  0 . 0 5  5  2  Temperature Range °C  ..wt.$ Ce Analysed  2  bottom top  6  0  0  .  and t h e t e s t was r e p e a t e d . . The d a t a - o b t a i n e d i s i n c l u d e d i n - T a b l e V, Experiments 5 0 not  and 5 1 -  I  n  experiment 5 1  o b t a i n e d u n t i l a temperature o f  &  1 5 5 0 ° C  complete r e m e l t i n g . d i d n o t occur below t h i s  symmetrical drop shape was was reached, i n d i c a t i n g temperature.  that  .  •  -35  A l t h o u g h the Ce d a t a was range no c o n s i s t e n t  Average  -  c a l c u l a t e d over a wide temperature  change w i t h i n c r e a s i n g temperature was  i n t e r f a c i a l e n e r g i e s and changes  in this  noted.  parameter  ( n e g l e c t i n g t h e temperature e f f e c t ) a r e r e p o r t e d i n T a b l e V I .  TABLE V I . Average Alloy  I n t e r f a c i a l Energy Changes Average  (dynes'/cm)  0  YlS  ^SV  ^LV  cos (180-0)  Interfacial Energy D i f f e r e n c e ft  II52  128  709  Fe-C-Ni  1135  118  533  - 176  Fe-C-Mn  126l  127  758  + if'9  165-  326 622 , 1033 •730  - 383 87 + 324 + 21  468  - 241  Fe-C  Fe-C-S Exp. Exp. Exp.  Exp. 12 36(<0.01 38(<0.01 39(<0.01  Fe-C-Ce Exp..30 Exp.,31 Exp. 32 Exp. ,33.  (0.022^^338 wt.# s) 801 wt.# S) 1115 wt.f S) 891 0  (-0.05 wt.$ Ce) 611 (0.025 vt.# C e ) 8 l 3 (-0.01 wt.$ Ce) 754 (-0.005 wt-$ Ce)876  Exp. 50 (-0.04 wt.$ Ce) 557 Exp. 51 (-0.04 wt,$ Ce) 67O  ft  . 141 152 145  14.0 138 137' 138 136 136  N e g l e c t i n g . t e m p e r a t u r e effects..  604 550 650  401 506  and assuming  b a s i s o f comparison  -  105  - 159 59 - 308 - 203  no change i n ^Qy'  ,  : - 36 - ; B. . R e s u l t s o f M e t a l l o g r a p h i c E x a m i n a t i o n o f the S o l i d i f i e d Drops 1.  Fe-C  Alloy  A wide range o f p r i m a r y g r a p h i t e forms p e r s i s t e d o v e r t h e r e l a t i v e l y s m a l l volume o f t h e drop.  The t o p e x h i b i t e d a l a r g e amount  o f w e l l d e v e l o p e d p r i m a r y g r a p h i t e , w h i l e t h e bottom o f t h e drop c o n t a i n e d a compact form o f p r i m a r y g r a p h i t e , and a much f i n e r D-type e u t e c t i c graphite.  The g e n e r a l s t r u c t u r e i s i l l u s t r a t e d i n F i g u r e 15.  The  compact g r a p h i t e does not have t h e smooth s u r f a c e o f a n o d u l e .  Instead,  i t resembles t h e c e n t e r o f a r o s e t t e . . The p r i m a r y g r a p h i t e has a c t e d as the n u c l e i f o r t h e e u t e c t i c g r a p h i t e p r e c i p i t a t i o n , e x p l a i n i n g the l a r g e g r a p h i t e - f r e e r e g i o n s s u r r o u n d i n g the k i s h f l a k e s . • P l a t e c) shows t h e f l a k e s w h i c h have d e v e l o p e d a t t h e i n t e r f a c e , t h e base a c t i n g as the n u c l e a t i n g a g e n t . . These f l a k e s a r e e s p e c i a l l y w e l l d e v e l o p e d when the drop i s h e l d a t t h e m e l t i n g t e m p e r a t u r e .  The drops adhered t o t h e base  p l a t e even when s o l i d i f i e d from t h e m e l t i n g temperature and t h e i n t e r f a c e appeared v e r y i r r e g u l a r . was  T h i s would i n d i c a t e t h a t some b a s a l a t t a c k  occurring.  To check t h i s e f f e c t a sample was m e l t e d , h e l d f o r l / 2 hour a t :  t h i s t e m p e r a t u r e , t h e n a l l o w e d t o s o l i d i f y . . Upon removing t h e drop from . the b a s e , s m a l l m e t a l l i c c r y s t a l s remained on t h e p l a t e s u r f a c e , as shown i n F i g u r e 16.  These c r y s t a l s were a n a l y z e d u s i n g powder X - r a y t e c h n i q u e s  and. f o u n d t o be e i t h e r r ^ - i r o n o r a m i x t u r e of  - i r o n and F e C - t h e o n l y  • h i g h i n t e n s i t y l i n e f o r F e C i s 2.01A°as compared t o 2.02 3  3  A  0  f o r the  h i g h e s t i n t e n s i t y , l i n e o f c A - i r o n . .Upon e x a m i n i n g the d r o p , p e a r l i t e present at the i n t e r f a c e .  was  The s t r a i g h t l i n e s n o t e d on t h e c r y s t a l s u r f a c e  were t h o u g h t t o be c l e a v a g e s t e p s .  - 37 -  F i g u r e Pp. a) b) c) d)  Fe-C Drop - Experiment  Ik  S t r u c t u r e near apex o f drop X 1 5 0 E t c h e d i n N i t a l X kOO Base r e g i o n of drop X 1 5 0 I n t e r f a c e C h a r a c t e r i s t i c s X 400  - 38  F i g u r e 16.  M e t a l l i c C r y s t a l s Remaining on Base P l a t e A f t e r Removal of Fe-C Drop  X  210  Some w e l l developed p r i m a r y f l a k e s were a l s o p r e s e n t  at  the  drop i n t e r f a c e i n d i c a t i v e o f the n u c l e a t i n g p o t e n t i a l o f the base  and  the occurrence 2.  of p r i m a r y g r a p h i t i z a t i o n a t the m e l t i n g E f f e c t o f N i and Mn  F i g u r e s 17 1.65$  Mn  the Fe-C  -  and  18  temperature.  Additions  i l l u s t r a t e the s t r u c t u r e of the 0.85%  alloys respectively.  Ni  and  A graphite d i s t r i b u t i o n s i m i l a r to that  a l l o y i s noted, a l t h o u g h  of  the g r a p h i t e i s s l i g h t l y c o a r s e r i n  both i n s t a n c e s .  sulphur.  3.  E f f e c t of Sulphur A d d i t i o n s  The  g r a p h i t e form changed markedly w i t h even s m a l l a d d i t i o n s o f  In the a l l o y s c o n t a i n i n g 0.039$ s u l p h u r and  g r a p h i t e f l a k e s were v e r y l a r g e e x t e n d i n g with no D-type e u t e c t i c g r a p h i t e b e i n g  0.022$ s u l p h u r  t o the g r a p h i t e covered  noted.  the  surface  F i gure  17. a) b) c) e)  Structure Top o f Etched Bottom Bottom  o f Drop C o n t a i n i n g  drop X I5O X kOO r e g i o n o f drop X 1 5 0 r e g i o n o f drop X 4 0 0  0.85$ N i  - Uo -  F i g u r e 18. a) b) c) d)  Structure  o f the 1.65$  Top o f drop X 150 Top e t c h e d X kOO Bottom o f drop X 150 I n t e r f a c e X kOO  Mn Drop  -  -kl  F i g u r e 19.  S t r u c t u r e of High S u l p h u r A l l o y s  a) 0.039$ s u l p h u r showing the l a r g e f l a k e s , no D-type e u t e c t i c g r a p h i t e and f r e e c a r b i d e i n the p e a r l i t i c m a t r i x X 100 b) 0.022$ s u l p h u r showing the l a r g e f l a k e s and forms X kOO  compact  c) Top of drop b) showing the l a r g e f l a k e s e x t e n d i n g and f r e e c a r b i d e i n m a t r i x X kOO  graphite  t o the  surface  d) Bottom of same drop showing the v e r y i r r e g u l a r s u r f a c e of the drop, the C£l80° c o n t a c t angle and the g r a p h i t e form. X 35  - k2 -  Figure 20.  S t r u c t u r e o f A l l o y C o n t a i n i n g from. 0.005 t o 0.01$  a) Large f l a k e s p r e s e n t near bottom o f drop and D-type e u t e c t i c g r a p h i t e X U00 b) E t c h e d showing the a s s o c i a t i o n of the l a r g e r f l a k e s w i t h quenched l i q u i d ( c a r b i d e ) . X kOO c) C e n t e r o f drop showing the f l a k e and compact g r a p h i t e , the p e a r l i t i c m a t r i x and the c e n t r a l f r e e c a r b i d e X 35 d) Bottom o f drop, showing the compact g r a p h i t e X kOO  S  - k} -  A compact g r a p h i t e form was f o r the two  a l s o present,  a l l o y s being depicted i n Figure  the g e n e r a l s t r u c t u r e  19.  F i g u r e 20 shows the s t r u c t u r e o f an a l l o y c o n t a i n i n g l e s s than 0.01  wt.$  s u l p h u r but more than the s u l p h u r l e v e l o f the b a s i c Fe-C  no w e t t i n g  or adherence t o the base p l a t e b e i n g observed and  s u r f a c e b e i n g darkened by the presence o f g r a p h i t e .  The  alloy  -  the drop  large flakes  were a g a i n n o t e d and were l o c a t e d near the base o f the drop as shown i n p l a t e a) and. p l a t e b ) . g r a p h i t e form and  The  upper r e g i o n of the drop c o n t a i n e d  D-type e u t e c t i c g r a p h i t e as shown i n plage  sharp t r a n s i t i o n e x i s t e d between the f l a k e and f r e e c a r b i d e s , as d e p i c t e d i n p l a t e d ) . n o t e d i n d i c a t e s pronounced s u l p h u r  The  a compact  c).  A  compact form and the massive  v a r i e t y of graphite  forms  segregation,However, the s m a l l  size  o f the drops p r o h i b i t e d any a n a l y t i c a l check.  k.  E f f e c t o f Ce  Additions  When Ce a d d i t i o n s were made, the g e n e r a l form o f the quenched drop was  quite d i f f e r e n t .  o f the g r e a t e r shrinkage  The  a s s o c i a t e d w i t h the n o d u l a r  o f an a l l o y c o n t a i n i n g 0.05  F i g u r e 21.  s u r f a c e c o l l a p s e d i n c e r t a i n areas g r a p h i t e , the  wt.$> Ce b e i n g d e p i c t e d i n F i g u r e  C o l l a p s e d Surface  indicative  o f Drop C o n t a i n i n g  surface  21.  0.05  wt.$  Ce  - kk - . . The  small button  molten drop, was  of m a t e r i a l apparently  examined a f t e r quenching.  The  not  s o l u b l e i n the  s u r f a c e was  i n c o l o r and upon s e c t i o n i n g and p o l i s h i n g the c e n t e r was  brownish  found t o  c o n t a i n s m a l l i n c l u s i o n s , as shown i n F i g u r e 2k p l a t e b ) .  Since  d i d not have the same c o l o r or form as the g r a p h i t e i n the  adjacent  drop i t was  these  thought t h a t t h e y were s u l p h i d e i n c l u s i o n s , , e x p e c i a l l y s i n c e  the p r i m a r y a c t i o n of a s p h e r o i d i z i n g agent i s the removal o f as a s u l p h i d e .  The  s u l p h i d e s b e i n g l e s s dense would f l o a t t o the  To check t h i s p o s s i b i l i t y the s e c t i o n e d sample was probe and a Ce  sulphur  scan was  top.  p l a c e d i n the e l e c t r o n  conducted. T a b l e ..VII shows the d a t a o b t a i n e d  comparative f i g u r e s f o r the 0.5  wt.$> Ce master a l l o y and t h e b a s i c  and Fe-C  alloy^ A l t h o u g h i t was  hoped t h a t any Ce  s e g r e g a t i o n w i t h i n the  c o u l d be determined by use  o f the probe, the  count r a t e between the 0.5  wt.$> Ce master a l l o y , the C e - f r e e  and the range of r e s u l t s o b t a i n e d f o r any  techniques.  Only the  s m a l l d i f f e r e n c e i n the Fe-C  crushed  l i n e s were n o t e d .  and  examined u s i n g X - r a y powder  T h i s i s e x p l a i n a b l e as  the  i n the  matrix.  As  i n the a l l o y s previously,examined,  shapes p e r s i s t e d a c r o s s the drop volume. be  the  undetectable.  amount of m a t e r i a l i s v e r y s m a l l and the i n c l u s i o n s a r e c o n t a i n e d iron  alloy  one p o s i t i o n i n d i c a t e d t h a t  c o n c e n t r a t i o n d i f f e r e n c e s expected would be  A s m a l l s u r f a c e b u t t o n was  drop  considered  i n d e t a i l as these  The  a wide range o f g r a p h i t e s t r u c t u r e o f f o u r samples w i l l  d e p i c t the range of shapes observed.  - 45 TABLE V I I . -Probe A n a l y s i s on S e c t i o n o f A l l o y C o n t a i n i n g (Beam c u r r e n t 0.09 ^ i a , 20 kv,.Reading the Ce  - P o s i t i o n on Sample  Lg  0.05 wt.$ l i n e at  71.6°)  Counts/min.  Near top o f drop  94, 104, 85, 70, 64, 85, 95  Sk, 8 0 ,  C e n t e r o f drop  84,  99, 107, 79, 75,  98, 100,  Near base o f drop  101,  93, 85, 84, 71, 92, 85, 93  Top d e p o s i t on drop  1159,  Fe-C A l l o y (No Ce  Ce  606, 500, 800,  a d d i t i o n ) 103,  9 0 , 102, 95,  Fe-C-Ce Master A l l o y - ( 0 . 5 wt.# Ce)  157,  86, 84  84,  87,  103,  Average  84  72,  81,  89  96,  90  761 92,  765  100,  1^0, 171, 159, 138, 135, 1^3, 129, 150  148  161,  F i g u r e 22 i l l u s t r a t e s t h e s t r u c t u r e o f a 0.005 wt.$ Ce ( a n a l y s e d 0.03 wt.$).  93  86, 89  alloy  P l a t e s a) and b) show the g r a p h i t e a t the t o p o f  the drop, p l a t e c) the t r a n s i t i o n from the f l a k e through the dense t o the f i n a l n o d u l a r form p r e s e n t the  nodules and r o u n d - t i p p e d  matrix  rosette  near the base o f the drop, arid p l a t e d.)  graphite f l a k e s present  a t the i n t e r f a c e .  The  i s p e a r l i t e , showing up as white a f t e r l i g h t p o l i s h i n g , f r e e c a r b i d e s  being d i s t r i b u t e d  throughout.  F i g u r e 23 shows the s t r u c t u r e o f a 0.04 wt...$ Ce a l l o y average 0.02 wt.$,  0.02 on t o p , 0.05 on bottom).  near the top o f the drop.  More g r a p h i t e  (analysed i s present  The s t a r - l i k e r o s e t t e s , p l a t e s a,), b) and c ) ,  decrease i n number i n p r o g r e s s i n g towards the base o f the drop, p l a t e d ) . Some dense nodules were p r e s e n t p l a t e s e) and f ) .  a t the lower boundary  o f the r o s e t t e forms,  The g r a p h i t e i n the lower r e g i o n was  sparsely distributed,  - 46 -  F i g u r e 22.  Graphite  S t r u c t u r e o f Experiment Ce added, a n a l y s e d  a) Top o f drop X 35 b) Top o f drop X  33  0.03$).  (the white i n t e r m e d i a t e  400  c) C e n t e r t o bottom o f drop X d) I n t e r f a c e X 400  35  (0.005 wt.$  region i s p e a r l i t e )  - ^7 -  F i g u r e 23.  a) b) c) d) e) f)  S t r u c t u r e of A l l o y C o n t a i n i n g Ce (0.04 wt.$ added^analysed 0.02 top - 0.05 bottom)  Top of drop X 35 Top o f drop X k00 Top of drop etched i n 2$ N i t a l X 35 Side o f drop showing t r a n s i t i o n r e g i o n X G r a p h i t e i n t r a n s i t i o n r e g i o n X 400 S t r u c t u r e etched i n N i t a l X 400  35  - kQ -  s p h e r o i d a l i n form, and  surrounded by a s h e l l of t r a n s f o r m e d  austenite,  plate f ) . . Figure  shows-the s t r u c t u r e of a 0.05  2k  d e p i c t s the heavy c o n c e n t r a t i o n shows the s u l p h i d e the drop apex. present the  i n the  Ce  alloy.  .Plate  o f nodules a t the top. of the drop,  i n c l u s i o n s present  i n the u n d i s s o l v e d  P l a c e c) and p l a t e d) r e p r e s e n t  a)  Plate  b)  m a t e r i a l at  the g r a p h i t e  shapes  c e n t r a l r e g i o n o f the drop, w i t h p l a t e e) i l l u s t r a t i n g  s p a r s e l y p o p u l a t e d base r e g i o n and  a s s o c i a t e d w i t h - t h e drop p e r i p h e r y . t h i s l a y e r i s shown i n p l a t e f ) . region  wt.$  of F i g u r e  23,  the l a y e r o f t r a n s f o r m e d  The  graphite  form c o n t a i n e d  austenite within  T h i s l a y e r i s a l s o p r e s e n t ' i n the  base  a g a i n accompanying the dense n o d u l e s . .In F i g u r e  2k,  where the nodules a r e p o o r l y developed, no p e r i p h e r a l l a y e r o f t r a n s f o r m e d austenite l600°C and  i s present. thus s h o u l d  Since  i t was  A l l t h r e e drops were quenched.from a p p r o x i m a t e l y have e x p e r i e n c e d the  not p o s s i b l e t o check Ce.  drop by the probe t e c h n i q u e , 5 mg top and bottom o f two records  same c o o l i n g r a t e s .  drops and  the c o n c e n t r a t i o n  segregation  i n the  samples of c u t t i n g s were taken from  analysed  . spectrographically.  d i f f e r e n c e s observed.  TABLE V I I I . -Ce Experiment Number  Concentration  a t Top  wt Ce Added  quenched  and  Bottom of Drop wt.$> Ce Analysed  30  0.05  0.02 O.O5.  top bottom  51  . 0.0k  0.02 0.05  top bottom  Table  the VIII  - 4  •  1  ."9*.  ,-  e  9  Figure  24 S t r u c t u r e of 0,05$ Ce a l l o y (0.05 added, a n a l y z e d 0 . 0 5 , 0 . 0 2 top and 0.05 bottom)  a) Top  of drop X 35  -  *.  b) S u l p h i d e i n c l u s i o n s i n s u r f a c e b u t t o n X 400  c) G r a p h i t e form i n t r a n s i t i o n  r e g i o n X 400  d) S t r u c t u r e c) etched i n N i t a l X 400  ie) S t r u c t u r e o f lower drop showing the compact g r a p h i t e and the o u t e r l a y e r of t r a n s f o r m e d a u s t e n i t e x 150  f) G r a p h i t e i n the o u t e r l a y e r X  400  - 50  •An average  f i n a l a n a l y s e s o f the drops  i s shown i n T a b l e  -  IX.  • TABLE. IX. Average•Spectrographic  Al 0.0002  Analyses A f t e r Test  Cr  Gu  Mg  Mn  0.0001  0.0006  0.0002  0.0005  To p e r m i t comparison  .  Mo  Ni  Si  0.003  0.02  0.02  Ti  V  0.0Q2  0.002  o f the s t r u c t u r a l changes a s s o c i a t e d w i t h  major a l l o y a d d i t i o n s , the s t r u c t u r e s o f the master a l l o y s are shown i n F i g u r e 25. similar.  The master a l l o y s can be compared as the c o o l i n g r a t e s a r e The Fe-C  (5.0$ C) a l l o y i s d e p i c t e d i n p l a t e a ) , coarse p r i m a r y  g r a p h i t e , some compact g r a p h i t e , and D-type e u t e c t i c g r a p h i t e b e i n g The N i a l l o y  (10.87 $ N i , 5.2$  noted.  C) i s shown i n p l a t e b ) , a much c o a r s e r  g r a p h i t e f l a k e b e i n g observed and o n l y s m a l l r e g i o n s o f p e a r l i t e c o n t a i n e d i n the  matrix.  p l a t e c ) . .The  The Mn  (18.0$ Mn,  5.25$ C) a l l o y i s i l l u s t r a t e d i n  c a r b i d e s t a b i l i z i n g power o f the Mn  this structure.  .The Ce master a l l o y  (O.53  $ Ce,  S e v e r a l l a r g e , dense nodules have d e v e l o p e d .  i s e v i d e n t when  5.7$  examining  C) i s shown i n p l a t e d ) .  However, i n g e n e r a l t h e  nodules a r e v e r y s m a l l and w e l l d i s t r i b u t e d throughout  the c a r b i d e m a t r i x .  Some carbon d e p o s i t i o n on the s m a l l nodules has o c c u r r e d as a s h e l l o f t r a n s f o r m e d a u s t e n i t e surrounds each n o d u l e . . These cannot be c o n s i d e r e d as n u c l e i f o r t h i s  The  reason.  s u l p h u r master a l l o y i s not i n c l u d e d as i t was  mixture o f FeS and F e S  2  and hence c o n t a i n e d no f r e e g r a p h i t e .  a .eutectic  -  51  -  - 52 C. • Thermodynamic C a l c u l a t i o n s Because t h e s u r f a c e t e n s i o n o f t h e Fe-C a l l o y s  i s markedly  a f f e c t e d by oxygen c o n t a m i n a t i o n , i t was necessary, t o determine the p e r UO cent oxygen expected i n the melt under t h e c o n d i t i o n s employed. has examined the e q u i l i b r i u m Fe  [ C ]  +  [  0  ]  Elliott  reaction  inFe  ^  C 0  (gas)  and has shown t h a t t h e e q u i l i b r i u m oxygen content a t l600°C i s a p p r o x i m a t e l y 0.0065$ " t carbon s a t u r a t i o n  a t 1 atmosphere p r e s s u r e ( e s s e n t i a l l y CO)... T h i s  a  was determined from t h e r e a c t i o n :  o ^— [oL . _  1/2  2  ' &F°  f i n Fe  = -27,930 - O.57 T = -28,998 ( a t 1600°C). The oxygen p a r t i a l p r e s s u r e was determined  from UO  - l o g P0  a t 1 atmosphere t o t a l p r e s s u r e = I5.2  2  x io"  P0 = 6.3 2  From  A F ° = - RT I n  o  f  ,  [POs] / 1  r l n L 0 J  $  F  16  e  2  = 0.00006  i n Fe  C o r r e c t i n g this, using:the a c t i v i t y c o e f f i c i e n t  o f oxygen i n  carbon s a t u r a t e d i r o n a t 1600°C i.e.,  log f  0 i n Fe =  (c) 0  =  I X 10  =  -2  0.006 wt. $  R e p e a t i n g t h i s c a l c u l a t i o n f o r a lower p r e s s u r e , i . e . 0.01 - l o g P0  2  atm.CO  a t carbon s a t u r a t i o n i s a p p r o x i m a t e l y 19 from  - 53 -  e x t r a p o l a t i o n o f E l l i o t t ' s data .'•  and u s i n g '  log [OL . „ = ' -6J.2 $ i n Fe f  10  =  Q  10" ' 4  ,  70 0::.in carbon s a t u r a t e d i r o n =  = 7.6 X 1 0 "  1 2  5  In the system i n • t h i s : t h e s i s ; t h e p r e s s u r e was m a i n t a i n e d a t 1 0 ~ or 1 0 " atmospheres. 8  5  mm  The e q u i l i b r i u m c o n c e n t r a t i o n o f oxygen i n t h e melt  would thus be expected t o be v e r y low.  The p a r t i a l p r e s s u r e o f oxygen a s s o c i a t e d w i t h molybdenum oxide was  c a l c u l a t e d as f o l l o w s : Mo0  ^  2 ( s )  M  = 137,000  AF°  a t 1600°C  O  (  P0  )  4 2  (  g  a  s  1  ,  )  = 63,200 -8  = 4 . 1 7 X 10  2  + 0  - .39.4 T  1  . .  s  atmospheres  S i n c e some FeO may be i n t r o d u c e d t o t h e system t h e a s s o c i a t e d p a r t i a l p r e s s u r e o f oxygen was a l s o determined. 41  FeO,, . '(1)  ^ = *ST-  Fe. + " ( i ) •  l/2 0 ^ " (gas) 2  2  = 56,830 - 11.94 T  AF°  a t 1600°C = 34,430 . . - P0  2  = 0 . 3 X 10  atmospheres.  S i n c e i t i s b e l i e v e d t h a t CeS i s formed w i t h Ce a d d i t i o n s t o t h e Fe-C a l l o y t h e thermodynamics  o f t h i s r e a c t i o n was checked.  The r e a c t i o n  of i n t e r e s t i s : ...  C  ( , .$ i n C s a t u r a t e d Fe) ' + .... ' .<(.$ i n C s a t u r a t e d F e ) " ^ S  •;.  C e S  (pu.re)  - 54 -  The  following free  energy equations  have been used: 39  a)  Ce  b)  Ce  1/2  +  s  AF°  =  — ^  g  = c) ;  2  CeS  g  ^  Ce  1  AF°  =  . „ x (% m Fe) /rf  1/2 S '  AF°  2  ^ g  f o r lack of appropriate  RT I n O.5585 140.13  C  ;  ^  =  S,, . . ($ i n Fe)  -.31,520 + 5.27 T  =  - 4F£  data  -11C0.T  5  9  ^ F° f o r t h e f o r m a t i o n o f cerium i r o n melt = A F°  y  -133,40039 ••+ 20T Ce 1  . Assuming an i d e a l s o l u t i o n  d)  J a  2200 - 2.0 T  Ce, v.  S  - AF°  - ^F°  =  s u l p h i d e from t h e elements in-.an -104,080 +27.7 T  Thus i n an i r o n a l l o y a t l800°K (1527°C) A F ° = -5^,080  cal.and  -6.57 log  K  = 6.57.  I f s o l i d CeS i s p r e s e n t ,  [$Ce][$S] = 10  .  Thus i n an  i r o n a l l o y i n which excess Ce (beyond t h a t r e q u i r e d t o form CeS) i s p r e s e n t , tne f i n a l S a c t i v i t y w i l l be extremely  low. .For example, i n a l i q u i d i r o n  c o n t a i n i n g 0.005$ S and 0.05$. Ce, the excess Ce c o n c e n t r a t i o n w i l l be approximately  0.03yo.  I f , as a l r e a d y assumed, Ce forms an i d e a l s o l u t i o n  i r o n , the e q u i l i b r i u m S a c t i v i t y (1$ s t a n d a r d  .The  effect  dilute solution  with  ,-5.05 s t a t e ) , w i l l be 10  o f C s a t u r a t i o n on the a c t i v i t y c o e f f i c i e n t  o f Ce i n  i n l i q u i d i r o n i s not known and t h e r e f o r e i d e a l i t y must be  assumed. . Under t h e same c o n d i t i o n s o f C s a t u r a t i o n l o g  f  i s about  0.7  s  and t h e e q u i l i b r i u m S c o n c e n t r a t i o n i n the a l l o y w i l l be o f the order o f 10 :  6 f  - 55 •IV.  DISCUSSION AND The  CONCLUSIONS  wide range o f  v a l u e s o b t a i n e d i n any  i n d i c a t i v e , o f the e r r o r s i n h e r e n t includes  i n the  the apparatus l i m i t a t i o n s and  which d i s t o r t the drop form. r e a l i z e d i n measuring the of-.* 0.01"  The  test is  e x p e r i m e n t a l approach  and  the a c t i o n of extraneous  greatest  z parameter.  forces  s i n g l e e r r o r i s probably  T a b l e I I I shows t h a t a v a r i a t i o n  i n t h i s parameter can account f o r a o ^ y  t h i s b e i n g a p p r o x i m a t e l y the  one  same as the  change o f * 1J0  c a l c u l a t e d standard  deviation.  Such a measurement l i m i t a t i o n c o u l d a r i s e from a l a c k of ness i n the  o r i g i n a l negative,. t h i s e r r o r b e i n g m a g n i f i e d i n  the d e s i r e d images.  contribute  to this effect.  I n a d d i t i o n any  be  oscillations,  spreading a c t i o n  movements from.the  p o s i t i o n would a l s o change the m a g n i f i c a t i o n .  sharp-  obtaining  I t i s p o s s i b l e t h a t e l e c t r i c a l l y , induced  m e c h a n i c a l v i b r a t i o n s or movements r e l a t e d t o the  dynes/cm,  The  could  original  drop shape c o u l d  also  d i s t o r t e d by an extraneous f o r c e or unsymmetrical w e t t i n g a c t i o n .  i s a l s o an  inherent  d i f f i c u l t y involved  Because the Fe-C from the m e l t i n g  would a l s o a f f e c t the as the Fe-C  occurred a t the  because the  r e s u l t i n g interface i s quite  of a r e a c t i o n a t t h i s i n t e r f a c e a r i s e s .  r e p r o d u c i b i l i t y o f the  a l l o y s were i n i t i a l l y carbon  • The  the z parameter.  drops are bonded t o t h e base p l a t e a f t e r c o o l i n g  temperature and  i r r e g u l a r the p o s s i b i l i t y  i n obtaining  There  r e s u l t s and  This  r e q u i r e an  explanation  saturated.  s t r u c t u r e of the a l l o y s i n d i c a t e d t h a t p r i m a r y g r a p h i t i z a t i o n  a t the m e l t i n g  i n t e r f a c e . . The  temperature, l o c a l i z e d , l a r g e f l a k e s d e v e l o p i n g upper r e g i o n  developed p r i m a r y g r a p h i t e . f l o a t i n g of primary graphite  i n the d r o p . c o n t a i n e d a h e a v i e r ,  . T h i s was  more  r e l a t e d t o a.lower c o o l i n g r a t e and  from the b a s a l  region.  a  - 56  -  Under " e q u i l i b r i u m " c o n d i t i o n s a f l u x o f carbon atoms i s b e i n g t r a n s f e r r e d between the g r a p h i t e and the m e l t .  Since i n the lower  areas  o f the drop l i t t l e p r i m a r y g r a p h i t e i s p r e s e n t , a f l u x between the. melt and t h e base p l a t e r e s u l t s . even though the Fe-C  T h i s would account  a l l o y was  f o r the i n t e r f a c e  i n i t i a l l y carbon s a t u r a t e d .  Because t h i s  r e a c t i o n does not s e r i o u s l y a l t e r the drop shape and because no compounds are formed, the s e s s i l e drop, approach  for  The average  the Fe-C  is s t i l l  1  erature of l450°C. ( i . e . , values ^  additional  valid.  a l l o y s i s i n q u a l i t a t i v e agreement  w i t h K o z a k e v i t c h ' s d a t a ^ which p r e d i c t s a,-; v a l u e f o r a s u l p h u r content of a p p r o x i m a t e l y  reaction  0 . 0 0 5 wt.$,  o f 1100 4.5  t o 1200. dynes/cm  wt-.$ C and a temp-  .However, the s e n s i t i v i t y l i m i t a t i o n b i n the S a n a l y s e s  0.01$  c o u l d not be determined) p r e c l u d e s a q u a n t i t a t i v e  comparison.  The average  c o n t a c t angle of 128°  f o r 1290  t o 1335°C compares  2 f a v o r a b l y w i t h a v a l u e o f 123-°  found i n K e v e r i a n ' s work , the  b e i n g a t t r i b u t a b l e t o t h e lower S content of h i s a l l o y s his. use  difference  (0.0005$)  a n  d  o f a randomly o r i e n t e d g r a p h i t e s u r f a c e . S m a l l a d d i t i o n s of Wi d i d not s i g n i f i c a n t l y change the s u r f a c e  energy  c h a r a c t e r i s t i c s i n agreement w i t h the d a t a r e p o r t e d , b y Kaufman  and W h a l e n ^ f o r a 1.5$ 1  C alloy.  T h i s would i n d i c a t e t h a t no atomic  inter-  a c t i o n s occur between the N i and C atoms.  No  changes were noted w i t h manganese a d d i t i o n s . u p . t o 1 . 6 5 w t . $ .  I t i s not p o s s i b l e t o p l a c e any emphasis on the sulphur d a t a due t o i t s p o o r r e p r o d u c i b i l i t y .  However, the g e n e r a l decrease  in  ^  T  „  • LiV  -  and  -  57  i n c r e a s e i n c o n t a c t angle w i t h s u l p h u r a d d i t i o n s i s i n agreement 2  with Keverian's  data  and the s t r u c t u r a l changes a r e s i m i l a r t o those  r e p o r t e d by .Garber  and W i l l i a m s  1  .  I t i s g e n e r a l l y , b e l i e v e d t h a t the g r a p h i t e - m e l t  interfacial  energy i s reduced  w i t h sulphur a d d i t i o n s .  In t h i s work i t was  t h a t the presence  o f s u l p h u r caused  carbon  excess  a t the drop s u r f a c e , a l t h o u g h i t was  expected  t o be  observed  precipitated  t h a t i t would p r e c i p i t a t e ,  onto the p r i m a r y g r a p h i t e a l r e a d y p r e s e n t w i t h i n the drop.  This  i n d i c a t e an i n c r e a s e i n t h e g r a p h i t e - m e l t i n t e r f a c i a l energy. the s u r f a c e energy d a t a was  i n s u f f i c i e n t to test this  . The a d d i t i o n o f Ce t o the Fe-C as p r e d i c t e d by M i n k o f f  18  .  However, the  h i g h e r temperature than the Fe-C  may  However,  hypothesis.  a l l o y a p p a r e n t l y decreased s/  Q  the  v a l u e s were o b t a i n e d a t a  v a l u e s . . S i n c e i t was  not p o s s i b l e  t o determine the temperature e f f e c t , a t r u e comparison o f the  values  cannot be made.  assigned  Although  s p e c i f i c v a l u e s cannot t h e r e f o r e be  t o the i n t e r f a c i a l energy d i f f e r e n c e s t h i s d i f f e r e n c e was w i t h i n c r e a s i n g Ce adsorbed  content.  i n t e r f a c e , a n e g a t i v e change i n  i m p l y i n g a p o s i t i v e change i n Y*  The established.  C  nodules  ~^^*  2  i n o b t a i n i n g the n o d u l a r form has been  are o n l y w e l l developed  of the drop where the Ce content i s the h i g h e s t .  i n the lower  onto the g r a p h i t e s u r f a c e .  region  I t i s possible that a  f l u x of Ce atoms i s r e q u i r e d t o ensure the development o f the t h i s Ce b e i n g adsorbed  i s being  2  importance of Ce . The  to increase  from:  z  _ I  RT  noted  Such a change i n d i c a t e s t h a t Ce  to the graphite-melt  ^^V"  nodule,  - .58 A l t h o u g h the  i n c l u s i o n s n o t e d i n the  drop s u r f a c e c o u l d be CeS, w i t h the v e r y low  S content  bottom Ce a n a l y s e s the drop.  "button"  the amount observed does not o f the a l l o y .  i n d i c a t e d t h a t Ce was  remaining  i s r e q u i r e d t o form CeS  In a d d i t i o n , the top and o n l y removed from the top  then s u l p h u r was  t o t h e s m a l l g r a p h i t e nodules p r e s e n t t h a t the Ce  content  "button"  i n the Ce master a l l o y .  two  The  expected.  fact  that  T h i s would be  Ce  consistent  These i n c l u s i o n s are.much c l o s e r  than are thei-nodules  h i g h e r Ce content•would be between these  CeS.  i n c l u s i o n s c o u l d be r e l a t e d  has been p r e f e r e n t i a l l y adsorbed on the i n c l u s i o n s .  packed i n t h e  of  weight  i s e x t r e m e l y h i g h i n t h i s r e g i o n would imply  w i t h the data p r e v i o u s l y c o n s i d e r e d .  the  a l s o o n l y removed  from t h i s r e g i o n , f u r t h e r d e c r e a s i n g the p o s s i b l e volume of  As an a l t e r n a t i v e e x p l a n a t i o n these  the  seem c o n s i s t e n t  Since a Ce d e p l e t i o n o f i n excess o f f o u r times the  of sulphur  on  I t was  i n the master a l l o y . not p o s s i b l e t o  t h e o r i e s as the volume of the i n c l u s i o n s was  Hence a  differentiate very  small  making. X - r a y a n a l y s i s u n s u c c e s s f u l . •  I t has been found t h a t the marked change i n the g r a p h i t e form i n p r o g r e s s i n g from the top t o the bottom of the Fe-C-Ce drops i s a s s o c i a t e d w i t h a change i n the Ce  content.  . The  s t r u c t u r e of the o t h e r a l l o y s i n d i c a t e s  t h a t the v a r i a t i o n i s p r i m a r i l y r e l a t e d t o e i t h e r a h i g h r a t e o f c o o l i n g i n t h e i n t e r f a c e r e g i o n or a decrease i n the n u c l e a t i n g p o t e n t i a l of t h i s resulting i n supercooling. Appendix V.  C o o l i n g r a t e c o n s i d e r a t i o n s are c o n t a i n e d  region in  A l t h o u g h i t i s not p o s s i b l e t o e s t a b l i s h the l i n e s o f heat  flow i t i s apparent t h a t a h i g h e r r a t e of c o o l i n g i n the i n t e r f a c e r e g i o n i s quite possible.  - 59 -  Such c o n s i d e r a t i o n s must a l s o a p p l y t o the Ce a l l o y s .  If i t  i s a c c e p t e d t h a t a nodule has a s u r r o u n d i n g s h e l l o f a u s t e n i t e above the e u t e c t i c temperature  than the n u c l e a t i n g s u r f a c e f o r a u s t e n i t e i s a l r e a d y  p r e s e n t and hence no e u t e c t i c s u p e r c o o l i n g would be expected.  However  as fewer nodules a r e p r e s e n t i n t h e b a s a l r e g i o n i t i s , l i k e l y the comb i n a t i o n s o f e f f e c t s which l e a d s t o t h e , f i n e r s t r u c t u r e s  observed.  .The c o n t a c t angle i n t h e Ce t e s t s d i d not change from 1300 1600°C.  In the development  s h e l l of a u s t e n i t e .  to  o f a nodule the g r a p h i t e i s surrounded by a  I f the e x p e r i m e n t a l analogy i s complete then the base  p l a t e - m e l t i n t e r f a c e i s analgous t o the nodule-melt i n t e r f a c e and. hence an a u s t e n i t e l a y e r s h o u l d d e v e l o p .  Because t h i s i s a s o l i d s h e l l  e f f e c t from i n c r e a s i n g the temperature would be expected.  little  However, i f the  main j u s t i f i c a t i o n f o r the presence o f the a u s t e n i t i c s h e l l i s the requirement t h a t an average carbon content.be m a i n t a i n e d t h e n a l a y e r o f a u s t e n i t e a t the i n t e r f a c e would not be  expected.  In p r o g r e s s i n g . f r o m the f l a k e t o the n o d u l a r form, o n l y s m a l l changes i n t h e i n t e r f a c i a l energy were n o t e d .  The shape was  more  dependent  on t h e Ce content and the p o s i t i o n w i t h i n the drop i . e . , the c o o l i n g and carbon d e p o s i t i o n  rate  characteristics.  . I t i s important t o note t h a t t r a n s i t i o n stages e x i s t i n changing from the f l a k e t o the n o d u l a r form. . T h i s would imply t h a t i t i s not simply a n u c l e a t i o n problem but i s a l s o dependent  on the s o l i d i f i c a t i o n c o n d i t i o n s .  The f a c t t h a t the f l a k e s f i r s t become rounded a t the t i p s i s g e n e r a l l y a s s o c i a t e d with a point d i f f u s i o n e f f e c t .  The second stage i s a compact  r o s e t t e shape, t h i s b e i n g a f u r t h e r i n c r e a s e i n the s u r r o u n d i n g a r e a p e r  -  u n i t volume o f p r e c i p i t a t e .  60  -  The f i n a l n o d u l a r form has a maximum  sphere o f i n f l u e n c e . ..Such a t r a n s i t i o n does n o t r e q u i r e a s p h e r o i d a l nuclei.  Rather, w i t h  increase  i n the c o o l i n g r a t e i n p r o g r e s s i n g  towards t h e base o f t h e drop, t h e d i f f u s i o n d i s t a n c e  o f the p r e c i p i t a t i n g  carbon i s d e c r e a s e d ^ a g r e a t e r sphere o f i n f l u e n c e and hence  greater  s u r f a c e p e r u n i t volume r e s u l t i n g t o p e r m i t the carbon d e p o s i t i o n .  In g e n e r a l . t h e  data i n d i c a t e s that the f i n a l graphite  form  i s more dependent on t h e growth c o n d i t i o n s t h a n on t h e i n t e r f a c i a l energies.  The i n t e r f a c i a l energy i s p r o b a b l y  o n l y o f majorvimportance  when d e a l i n g w i t h t h e n u c l e a t i n g shape, the. f i n a l form b e i n g a r e s u l t o f t h e r a t e s o f d e p o s i t i o n on t h e v a r i o u s  crystal  faces.  -  -V.  61  -  RECOMMENDATIONS FOR FUTURE WORK -A s i m i l a r i n v e s t i g a t i o n  u s i n g i r o n o f a much h i g h e r  purity  and master a l l o y s having, the. d e s i r e d compositions would e l i m i n a t e s e v e r a l o f t h e . d i f f i c u l t i e s e x p e r i e n c e d i n t h i s work.  I f drops o f  a p p r o x i m a t e l y two grams were used t h e r e p r o d u c i b i l i t y would be much improved.  The i n c l u s i o n o f f a c i l i t i e s p e r m i t t i n g . t h e d e g a s s i n g o f  the. base p l a t e p r i o r t o t h e t e s t would a l s o a i d i n t h i s r e s p e c t .  A l t h o u g h t h e s e s s i l e drop technique can y i e l d v a l u a b l e i n f o r m a t i o n a more f r u i t f u l approach would be t o study-the growth k i n e t i c s and t h e development morphology o f t h e v a r i o u s g r a p h i t e forms. I n f o r m a t i o n o f t h i s nature i s r e q u i r e d b e f o r e shape t r a n s f o r m a t i o n s can be c o m p l e t e l y  understood.  - 62 -. V I . APPENDICES APPENDIX I . E x p e r i m e n t a l D i f f i c u l t i e s and E r r o r s Inherent i n the S e s s i l e Drop;Approach  A l t h o u g h the s e s s i l e - drop t e c h n i q u e seems simple, many hazards b e f a l l the unwary.  To impart some, a p p r e c i a t i o n f o r these  difficulties  •k  s e v e r a l o f the experimental, problems w i l l be b r i e f l y d i s c u s s e d .  j.Sample  Contamination  1. Sample c o n t a m i n a t i o n i s p r o b a b l y t h e most important factor.  . S p e c i a l care must be taken t o e l i m i n a t e any c o n t a m i n a t i n g  Where o x i d a t i o n i s a problem,  source.  as w i t h i r o n , i t i s n e c e s s a r y t o e l i m i n a t e  oxygen from the system and t o remove, i f p o s s i b l e , any. oxide from.the  single  contamination  m a t e r i a l b e i n g melted. . Use o f a t i t a n i u m o r molybdenum s u s c e p t o r  a l t h o u g h - t h e l a t t e r i s l e s s e f f e c t i v e , a i d s i n r e d u c i n g the oxygen p a r t i a l pressure i n an.induction u n i t .  To ensure t h a t no oxide c o n t a m i n a t i o n i s  p r e s e n t i t may. be n e c e s s a r y t o r e s o r t t o use o f an i n e r t atmosphere.  However,  s i n c e the v a l u e s o b t a i n e d a r e o n l y r e p r e s e n t a t i v e o f t h e c o n d i t i o n s employed, i n f o r m a t i o n from such experiments  may. be l e s s u s e f u l .  -Some problems may  a l s o a r i s e from c o n t a m i n a t i o n o f t h e p l a t e s u r f a c e by the i n e r t gas.  • I f p o s s i b l e , i t i s recommended, t h a t the base p l a t e and apparatus be degassed  a t a h i g h vacuum and a t a temperature  above t h a t t o be.used.  T h i s r e q u i r e s t h a t the sample be t r a n s p o r t a b l e t o the h e a t i n g s e c t i o n f o l l o w i n g the degassing operation.  . To p r e v e n t c o n t a m i n a t i o n i t i s a l s o n e c e s s a r y t o trap, out d i f f u s i o n pumps and any source o f o i l o r g r e a s e .  -  2. Problems Inherent  i n the Drop Shape Approach  .The drop sample w i l l be i t s vapour p r e s s u r e  t a i n e d by t h e  system.  However, when the  o f the melt i s g r e a t e r than the vacuum main-  system, the m e t a l w i l l c o n t i n u o u s l y v a p o r i z e .  such a c o n d i t i o n cannot be slight  i n a s t a t e of e q u i l i b r i u m o n l y when  i s l e s s than t h a t o f the  e q u i l i b r i u m vapour p r e s s u r e  63.-  Although  c o n s i d e r e d an e q u i l i b r i u m c o n d i t i o n , . o n l y a  change i n drop dimensions s h o u l d . r e s u l t . • I f the e q u i l i b r i u m  p r e s s u r e were s i m i l a r t o the vacuum maintained  t h i s would not be  a  s e r i o u s problem.  As  i n any w e t t i n g experiment, much emphasis i s p l a c e d on the  i t i o n of the s u r f a c e and  on the p o s s i b i l i t y ' o f v a r i a t i o n i n t h e  cond-  contact  angle when d e a l i n g w i t h an a d v a n c i n g as opposed t o a r e c e d i n g i n t e r f a c e . • k2  B a r t e l l and Wooley c o n t a c t angle  have shown t h a t f o r an a d v a n c i n g . i n t e r f a c e  depends on t h e p r e v i o u s  r e c e d i n g i n t e r f a c e the angle  the  s u r f a c e treatment, whereas f o r a  i s dependent on the  wetted s u r f a c e , - b o t h b e i n g c o r r e c t a n g l e s  c h a r a c t e r i s t i c s o f the  f o r the s p e c i f i c  conditions  i nvolved. The  p o s s i b i l i t y that- the c o n t a c t angle may  a l s o a r i s e s . . T h i s a f f e c t can be  v a r y around the drop  reduced, by t a k i n g s e v e r a l measurements  around- the. drop. The  accuracy  o f the t e c h n i q u e  i s a l s o dependent on the volume 1+3  o f t h e drop, t h i s b e i n g a f u n c t i o n o f x/z. that an optimum range f o r x/z  i s 1.15  "to  Baes and Backs 1.7  have shown  - 6k The  greatest d i f f i c u l t y  i s experienced  i n determining  i n obtaining.the  d e s i r e d parameters  the d i s t a n c e from the maximum drop diameter  t o t h e apex, i . e . , t h e d i s t a n c e z. . T h i s i s e s p e c i a l l y drops h a v i n g  a h i g h s u r f a c e t e n s i o n s i n c e the shape approaches t h a t o f  a sphere, and f o r drops having has  i n c l u d e d a technique  accurate  true f o r small  determination  a c o n t a c t angle a p p r o a c h i n g 90 •  Bashforth  where by. u s i n g s u c c e s s i v e a p p r o x i m a t i o n s an  o f t h i s parameter c a n be made.  mathematical m a n i p u l a t i o n s  are necessary  However, many  b e f o r e t h i s i s a workable  solution.  3_ Equipment Design Any w i l l result  e r r o r s i n t h e o p t i c a l system used t o r e c o r d t h e drop shape  i n poor r e p r o d u c i b i l i t y .  T h i s e f f e c t can be minimized b y  a v o i d i n g t h e need f o r enlargement o f t h e image.  Any  u n c e r t a i n t y i n t h e m a g n i f i c a t i o n w i l l markedly a f f e c t t h e  reproducibility  s i n c e the square o f t h i s parameter i s i n v e r s e l y p r o p o r t i o n a l  . Image d i s t o r t i o n s effects.  may a r i s e due t o temperature induced: r e f r a c t i o n  The magnitude o f t h i s e f f e c t  can be determined b y p h o t o g r a p h i n g  an o b j e c t o f known s i z e under i d e n t i c a l temperature and p r e s s u r e Considering the d i f f i c u l t i e s those  conditions.  i n v o l v e d i t i s c e r t a i n l y t o the c r e d i t o f  i n v e s t i g a t o r s who a r e a b l e t o o b t a i n r e p r o d u c i b l e  results.  - 65 APPENDIX I I . P r o d u c t i o n and- P r o p e r t i e s o f P y r o l y t i c  Graphite  36,- kk, 45 P y r o l y t i c graphite p l a t e i s produced  . l i k e t h a t employed f o r t h e base  by c r a c k i n g a hydrocarbon  m a i n t a i n e d a t a p p r o x i m a t e l y 2000°C.  gas onto a f l a t s u r f a c e  .The r e s u l t i n g dense deposit- i s  composed o f carbon atoms a r r a n g e d i n two d i m e n s i o n a l hexagonal  networks  a l i g n e d p a r a l l e l t o the d e p o s i t i o n p l a n e . - A d j a c e n t l a y e r s e x h i b i t random o r i e n t a t i o n s p r e v e n t i n g the m a t e r i a l from h a v i n g t h e t h r e e d i m e n s i o n a l characteristics of a graphite single c r y s t a l .  . This c r y s t a l anisotropy  i s t r a n s f e r r e d t o the bulk p r o p e r t i e s of the material, a high e l e c t r i c a l and t h e r m a l c o n d u c t i v i t y b e i n g observed f o r d i r e c t i o n s p a r a l l e l t o t h e b a s a l p l a n e whereas t h e m a t e r i a l behaves as an i n s u l a t o r i n t h e d i r e c t i o n perpendicular t o the plane. The m a c r e s t r u c t u r e o f a d e p o s i t - i s determined of t h e p r e c i p i t a t i n g s u r f a c e .  by the roughness  Growth n u c l e a t e s a t s p e c i f i c  r a d i a l type o f development e n s u i n g .  locales, a  The end r e s u l t i s t h e c o n i c a l growth  v i s i b l e under p o l a r i z e d l i g h t , t h e s t r u c t u r e o f t h e m a t e r i a l used b e i n g shown i n F i g u r e 26.  The s u r f a c e o f t h e m a t e r i a l has a "pimpled" t e x t u r e  as a r e s u l t o f t h i s development.  - 66 -  F i g u r e 26.  S e c t i o n Through the P y r o l y t i c Polarized light  Graphite X  100  - 67 -  APPENDIX I I I . S e s s i l e Drop Data  Time A f t e r S t a r t ot M e l t i n g  Mag., o f Photo  Temp. °C Fe-C  x  z x C inches^  1  z  1  t ~ fo.(dynekycm)  Alloy  Experiment No. 14 at melting + 1 see. + 2  12.88  k  + 7 + 8 9 10 11 12 13  + 14 + + + + + + + + + + + + + 2 k  1.125 1.150  0.893 0.917  1.155 1.240 •1.165 1.170 1.235 1.242 1.173 0.937 1.242 1.163 1.240 1.155 1.240 1.150 1.247 0.945 1.160 1.250 1.160 1.257 1.153 . 1.247 1.170 . 1.240 1.160 1.247 0.972 1,175 1.244 1.165 1.247 1.170 1.241 1.150 1.180 1.257 1.261 1.175 1.256 1.172 1.007 .1.262 1.183 1.250 1.170 1.250 1.150 1.250 .1.170 1.260 1.005 1.163 1.260 1.180 1.015 1.185 1.257 1.169 1.073 .1.257 1.068 1.183 1335 1.257  + 5 + 6  + + + + +  1.232 . 1.230  1.870 1.860  1.235  + 3 +  1325  15 16 .17 18 19 20 21 22 23 2k 25 26 27 min.25 s e c . min.10 s e c .  I.865  1.863  791 1126 1134 1164 1438 1379 1060 1076 909 1103 1034 916  145  140  138  139  1248 1.848  1164 1364 1164  135  1295 897 1318  1144 1.840  1174 1242 .1184  133  909  .. 1184 1006 1199 1.815 . 1405 I . 6 9 6 1126 I . 7 0 8 1354 1.837  132 127 126  Experiment No. 19 at start + 1 sec. +2 + 3  +4 + 5 + 6 + 7  11.40  '  1325  1.030 1.035 1.030 1.030 1.032 1.034 1.032 1.035  0.940 O.965 O.965 O.960  O.97O O.965 O.970 0.970  O.685  1.635  O.702  1.640  721 979 1032 970 1123 989 1120 1070  continued.  150  148  -68  Time A f t e r S t a r t of M e l t i n g . + 8 sec. + •+ + + +  9 10 11 12 13  +  14  Mag., o f Photo .. 1 1 . 4 0  Temp. °C 1325  . X  1.032 1.032 1.032 .1.035 • 1.035 1.035 1.035 1.035 1.032 .  .+ + + •+ + + + + + +  15 16 17 18 19 20 21 22 23 24 2 min.. 12 s e c . 3 min..kQ s e c .  1.035 1.040  1.035 1.032 .i.o4o 1.035 1.037 1.033 . 1.035 1.037  z X t inches") O.98O O.93O O.965 O.97O O.965  1  O.695  (dynes/cm) 1.632  0.975 O.97O O.97O O.97O  O.967 0.975  0  146 1370 1370 1031 . 1071 979 1072 994 1170 1122  0.97] O.965  0.975 O.965 O.965 O.965 O.978 O...96O  -  0,707  1.630  1039 1006 1167  146  1033 922 0.720  1.620  0.740 -1.695 I.070 0.813 0.861 • I . O 6 3  979 1213 941 1024 1150  145 144 135 129  Experiment No..20 ( M e l t i n g conducted on n u c l e a t i n g s u r f a c e o f p l a t e ) + 16 s e c . + 17 + 18 + 19 . + 20 + 21 + 22 + 23 +: 24 + 25 + 26 + 27 + 28 + 29 + 30 •+.?1 + 32. + 33 + .34 + 35 + 42 3 min. 3 min. 2 s e c . 4 min. 4 min.,1 s e c . 5 min. . 5 min..1 s e c . 9 min. 9 min. 1 s e c . 10 min. 2 4 s e c .  10.35  1280  1.053 1.068  1.062 I.O65 I.O65 1.070 1.060 I.O67 I.O67 I.O65 1.062 1.065 1.062  0.975 0.975 O.988 0.993 O.98O O.97O O.985 0.977 0.975 0.973 O.988  0.715  1.695  0.712  1.675  0.710  1.675  0.975 O.7I5 O.983 1.675 O.99O I.O65 I.O65 O.985 1 . 0 6 9 - O.98O O.978 0.694 •I.O65 1.675 0,980 I.O67 I.O65 0.977 I.070 I.67O 0.725 0.973 I.O55 0.730 I . 6 O 5 0.955 1.050 O.967 I.585 0.735 •1.050 O.97O 0.735 1.582 .1.050 0.954 O.752 1.570 1.047 O.96O 0.752 1-575 .1.052 O.962 O.76O 1.570 I . O 5 O O.965 0.757 1.575 O.957 1.050 1.535 0.795 1.052 0 , 8 0 0 . 1.550 O.965 I.O55 1330 O.965 • 0 , 8 4 0 1.520  1262 964 1231 1282 1052 889 1210 1002  150  971 968 1231 - 993  152  1044  149  1212 ll4o 1014 1031  152  151  1033 1021 917 917 IO98 1151 934 1070 IO85 1071 964 1036 1019  continued.  151 149 148  147 147 145  145 144 l4l l4o 136  - 69 -  Time A f t e r S t a r t of M e l t i n g  Mag. o f Photo  Temp. . °C  .  1290  X  z x L inches')  Z± 1  li  LV , c0 (dynes/cm )  Experiment No..27 + 20 s e c . + .30 2 min. 18 s e c . 3 min.. 48 s e c . 5 min..48 s e c . 6 min. 36 s e c . 9 min. 42 s e c . 10 min. 48 s e c . Experiment No. +1  12.90  1375 1420 1415  1.765 1.757  1.445 1.445 1.455 1.454  2,385 2.380 2.320 2.287 1.335 .2.245 1.485 1.467 2.090 I . 6 O 5 1.660 . 1.640 •1.662 2.090 1.650 2.090 1.635  I.I67  I.170 1.260  1200 II87 1300 1220 1125  146 146 138 132 127 110 , 111 111  150 134 125 122  28  11.04  sec.  1335  + :30 1 min. 2 min. 12 s e c . Experiment No.  .1.600 I.6O7 . I.6O5 1.612 I.67O 1.740  1.285 1.282 1.305 1.327  1.142  1.535 1-555 .1.550 1.547  1.320 1.355 1.360 1.355  I.589 1.632 1.628 1.622 1,620 1.618 1.615  1.480 1.500 1.504 1.490 1.498 504 1.498  1.175 I..I9O 1.205  O.885 1.035 1.147  I.96O 1.790 1.720  1.197  1.695  1105 1260 1210 1212  1.115 1,300 1.355 I.345  2.170 2.060 I.985 1.955  1080 1250 1310 1295  152 133 129 129  1.281 1.361 1.360 1.352 .I.36I 1-357 1.356  2, 320 2. 275 •2, 250 2, 260 2. 265 2, 255 2, 250  1220 1025. 1110. 1010 1100 1210  132 131 130 131 129 130 129  29  + 1 sec.  10.28  1345  + 48 2 min. 3 min .Experiment No..55 + 2 3 5 7  20 s e c . min. min. 42 s e c . min. 30 s e c . min. 30 s e c . 14 min 12 sec. 30 min  I5..8O  1335  Fe-C-Ni Experiment No. + 2 1 sec. + 423 min. 4 min. 6 min. 8 min. •12,2 min. 19 min.  .1140  (0.85$ N i )  45 13,52  1285  I . 5 8 6 1.375 1.610 ,1.435 .I.656 1.490 .1.655 1.485 .1.659 1.485 1.662 1,490 1.470 1.687 1.480 1.675  87O 2.165 1.279 .1129 1.381 2.135 .1.505 • 2,000 • 1321 2.-005 1274 1.535 2.010 1.542 1232 2.005 1258 1.547 2.010 942 1.565 1051 I.985 1.555 continued.  139 128 120 118 117 118 118 118  70  Time A f t e r S t a r t of M e l t i n g  -Mag., o f Photo  Temp. °C  z x (inches ! >  J  (dynes/cm)  Fe-C-Mn ( 1.65$ Mn) Experiment- No... 43 1 min..24 s e c . 5 min.,50 s e c . 6 min. 8 min. 9 min. 50 s e c . 11 min. 12.7 min. 14.1 min.  12.02  1295  1.810  1.847 I.865 1330 - 1365 .1385 .  • 1^30 1455  I.87O  :  1.587 1.595 1.610  •1.645  • 1.860 1.605 1.860 1.598 I.827 1.585 1.831 1.615  1.365 1.545 1.585 1.640 : 1.655 1.655 1.655 1.657  2.515 -2.435 2.360  1302 1205  145  2.325 2.310  1233 1452 1190 •1145 1185 1380  133 133 127 126 126 122 122  2.345 2.310 2.300  Fe-C-S Experiment No.. 12•(Data t a k e n from s o l i d i f i e d drop) . + 1 1 min.  10.32  1555  0.950  0.800  0.615  1.255  338  165  9-57  1295  I.257 1.257 1.260  1.035  0.915  1.720  630 638 710  156  Experiment No..36 1 min. 30 s e c . 1 min. 31 s e c . 32 33 34 35 36 4 min. 4 min.l sec. 2  1320  1.257 1.257 I.257 1.255 I.250  1.247 1.242 1.247  3 4  1.245 1.242  5 7 min. 7 min. 1 s e c . 2  1340  3 4  .1.265 1.255 1.260 I.256  1.057 1.051 1.050 1.035 1.055 1.100 1.105  0.920 0.976  1.705  695 690 631 631 1012  155 141  1075 1019  1.095 I.090 1.090 1,090  O.98O  I.O85  1.080  967 975 980 828 738  1.060 1.070  141 132  1.255 • 1.075  1.072  767 706 782 758 807  152  1.250  0.845 1.840 ,1040 0.843 1,860 1040 0.840 .1.870 1059 0,835 I . 8 9 0 1183  152 153 153 152  1162 1205  153 152  1.255 I.256  5 6  1.040  1.055 I.070 I.O65  Experiment No.. 58 .+• 30 s e c . 1 min.. 54 s e c . 4 min. 30 s e c . 6 min. 30 s e c . 8 min..42 s e c . 10 min..42 s e c .  IO.56  1335  I.25O  1.255 1.247 1.255 .1,250  1.125 1.125 1.130 1.135 1.140 1.140  0.837 0.837  1.875 1.880  continued.  71  Time A f t e r S t a r t of M e l t i n g  Mag. o f Photo.  Temp  X  • . °c  — 1 X Cinches "i  z  :  s N  1  i LV (dynes/cm)  (0  Experiment No..39  + 48 s e c .  9-55  1295  1..192 1.190 1.207 1.205  1.015 1.025  1.195  I.O65 1.060 1.050 I.O55  1.902 1 min. 30 s e c .  2 min. 18 s e c . • 4 min. 6 min. 8 min. 10 min.  1305 1285  1.197 .1.200 1.195 1.195  Experiment No.. 30 5 min. 36 s e c . 10-min. 12 min. 16 min.  1.207 1.205 1.205 1.205 1.202 1.205 1.200 1.205 . 1.205  1.055 I.O55  0.912 1.688 O.887 1.720 0.920 . 1 . 6 9 0 1.710 1.700 1.725 1.695 1.680 1,685 1.700  0.931 O.917  1.035  1.040 1.030 1,045 1,035  1.040 1.050 I.O65 1.055 1.060 I.O65  •1.715 1.700 1.768 0.902 1.685 1.700 0.917 O.9O5 1.700 0.902 1.700 O.895 1.720 0.910.. 1.705  704 780 930 928 1063 970 875 928 ,794 812 758 794 800 813 869 1075, 945 1015 1082  146 149 145  143  145  146 145 143  145 145 142  Fe-C-Ce 12.70  1445 .1530 .1620 .1605  1.711-1.455 1.735 1.385 I.705 1.400 1.702 1,380  1.357 1.417 1.405  2.345 792 2.185 510 2.155 • 590 2.140 55O  1.535 1.520 1.485 1.470 1.445 1.445  1.400  i4l 142 1^.0 l4l  Experiment No.. 51 3 min. 6 min.. 30 s e c . 11 min. 13 min. .48 s e c . 19 min. 48 s e c . 20-min. 54 s e c . 22 min.  8.68  1305 1375 1447 1485 1615 1630 1630  1.202 1.210 1.215 1.205 1.210 1,194 - 1.192  1.045 1.034 1.005 O.97O  1.000 1,012 1.015 1.016  0.995 1.030 1.035  1.055 1.060 I.O65  1.010 1.019 1.024 1.010  0.895 O.87O 0.900 O.885  O.817 O.825 O.83O O.827  104 0  138 136 138138  1.437-  907 704 580 650 885 930  1.420 I.37O 1.370 I.38O  860 615 795 745  138 138 138 136  1.545 1.540  940  139 139 139 138 128 125  131 127 125  •Experiment No. 52 13 16 17 18  min. min. min. min.  48 12 18 42  sec. sec. sec. sec.  . 8.55  1520 -1635 1640. 1645  Experiment No. 33  48  sec. 2 min. 8 min. 54 isec. l 4 min. 42 s e c . 19 min. 36 s e c . 22 min. 30 s e c .  8.45  1315 1323 1455 1535  i64o 1650  1.135 " 0 . 9 8 3 0.919 1.141 O.980 0.935 1,190 1.000 ' 0 . 9 7 5 1,156 • 0.995 0.945 1.160 1.000 1.022 0.980 1.012 1.127  1.565 • 1.510 1.450 1.380  895 775 880 875 .980  continued.  - 72 Time A f t e r S t a r t of M e l t i n g Experiment Mo. 48 1 min. 6 s e c . 3 min. 4:min.. 18 s e c . 5 min..30 s e c .  Mag. o f Photo  Temp. °C  z x-tinches) 1  ( M e l t i n g c a r r i e d out on the n u c l e a t i n g 11.75  (dynes/cm) .surface)  1305 . 1305 . 1405 . 1405'  1.578 1.567 1.590 1.585  1.360  1.060  2.280 2.260  915 830  1.335 1,360 1.370  1.075 1,110 1.020  2.27O  855 855  157 156 157  1605  1.597 1-595 1.600  1.325 1.330 1.297  1.400 1.405 1.402  1.915 1.910 1.895  578 594 500  130 130 131  1.620 1.625  1,360 1.370  1.300 ,1.345  2.095 2.085  660 680  142 136  2.273  160  Experiment No. 50 10 min. 11 min. 12 min.  12.64  Experiment No. 51 12 min. 30 s e c . 13 min. 3 0 - s e c .  12.35  • 1600  - 73 APPENDIX IV. S t a t i s t i c a l A n a l y s i s o f Three Fe-C T e s t s  In each case the drops were t a k e n a t 1 second  intervals.  Experiment l 4 Sequence '  1-12  -24 -36  - 48 - 60 - 72  - 84 - 96 -108 -120 -132 -Ikk -156 -168 -180 -192 -20k -216 -228 -240 -252 -264 -276 -288 -:300 -312 -324  Xxv 1126 1134 1164 1438 1379. 1060 . 1076 909 1103 1034 916  1248 ' 1164 1364 1168 1295 • 897 1318  1144 1177  1242 1184 909 1184 1006 1199 1405 .31,240  ( *LV"  1 1  - 31 - 23 + 7 +281 +222 - 97 -.81 -248 -.5* -123  -24l + 91 + 7 +207 + 11 +138 -260 +161 - 13 + 17 + 85 + 27 -248 + 27 -151 . + 42  +248  57)  (VLV-1157)* 961 529 49 78961 49284 9490 6561 61504 2916 15129 58081 8281 49 42849 . 121 19044 67600 25921 169 289 7225 729 61504 729 22801 1764 61504 603,963  -  - 7^ -  Experiment 19  Sequence - 12 - .24 -36 -48 - 60 - 72 - 84 - 96 -108 -120 -132 -144 -156 -168 -180 -192 -204 -216 -228 -240 -252 -264 -276 -312  "  ;  979 1032 970 1123 989 1120 1070 1370 1370 1031 1071 979 1072 4 1170 1122 1039 1006 1167 1033 922 979 1213 941 9 9  25,762  (^^-1073) -94 - 4l -103 + 50 - 84 + 47 - 3 +297 +297 - 42... - 2  - 9h  1 - 79 + 97 + 49 • • --34 + 67 + 94 - .40 -151  -k 9  +140 -132  (  -1073)" 8836 1681 10609 .2500 7056 2209 9 88209 88209 1764 4 8836 1 6241 9409 2401 1156 4489 8836 1600 22801 8836 196OO  17424 322,716  - 75 -  Experiment 20  "Serine!  ( X L V "  1262 •964 1231 1282 1052 889 1210 1002 971 968 1231 993 1044 . 1212 ,ll4o .1014 1031 1033 1021 917  1.-190 -200 -210 -220 -230 -240 -250 -270 -280 -290 -3OO  -310 -320 -330 -340 -350 -360 -370 -380 • -390  1  0  +181 -115 +152 +203 - 27 -190 +131 - 77 -108 •,111 +152 - 86 + 35 +133 + 62 - 65 - 48 - .46 - 58 -162  7  9  )  (  •  21,580  (dy^es^cm)  9  '^  32761 13225 23104 41209 729 36100 17161 59?9 11664 12321 23104 7396 1225 17689 3844 li225 .2304 2116 3364 26244  s  Standard Deviation (dynes/cm)  7  Treatment  * 16  Mean  0  285,714  Results o f • S t a t i s t i c a l Experiment Number  ILV^  Exp.  *  2<r  Theor. . Exp. Normal ^ • 1° Distn.  14  1157  150  . 63  68.2  100  19  IO73  116  79  68.2  92  20  1079  120  55  68.2  100  Theor.  95-46 • 95-46 95-46  -  76  -  • APPENDIX V. Cooling,Rate Considerations  Because the drop samples show a much f i n e r . s t r u c t u r e i n the b a s a l r e g i o n i t i s n e c e s s a r y t o c o n s i d e r the p o s s i b l e c o o l i n g c o n d i t i o n s present.  One would.at  first  expect a slower c o o l i n g , r a t e and hence  c o a r s e r s t r u c t u r e i n t h i s r e g i o n due t o t h e l a r g e heat content of the base. The approximated  l o s s o f heat by r a d i a t i o n t o the surroundings .can be by examining  s i m i l a r t o those  the f o l l o w i n g model, the dimensions  being  used.  5 The temperature  s u r r o u n d i n g s are c o n s i d e r e d t o be a t a c o n s t a n t low  - t h i s i s approximately, t r u e as the molybdenum s u s c e p t o r l o s e s  i t s . h e a t e x t r e m e l y r a p i d l y and i s b l a c k w i t h i n 2  seconds.  The drop and base p l a t e are considered; t o be a t the same tempe r a t u r e a t . t h e i n s t a n t the power i s removed. r a d i a t e heat m a i n l y . i n t h e  The. drop s u r f a c e w i l l .  d i r e c t i o n t o the b l a c k s u r r o u n d i n g s .  - 77 T h e . a c t u a l r a d i a t i n g . a r e a , w i l l he and  the  s m a l l band below the  center  .This angle below the  tan"  0  1  .!.  =  0  1 sin . 2 . 5 =  7-85  line.  =  0.137$  -  A r e a of a d d i t i o n a l r a d i a t i n g  2 ffr  =  The drop, i s  surface jfd  .<(  X  (1)  strip  (7.85' X .360  2^)  .<8.6  area involved,  c o n s i d e r i n g - i t as a  spheroidal  +0.8.6  2  2  (upper h a l f ) •+•  (band below the  center)  7-15  =  The  sphere  center i s :  £ 0°  B  the upper h a l f of the  -  p l a t e surface  w i l l r a d i a t e energy m a i n l y i n the  direction  shown."  . Radiating  Area  =  5 X 5  -  ^(1)  =  21.86  E m i s s i v i t y . o f pure i r o n from 1000°C t o 1500°C i s a p p r o x i m a t e l y (Metals Handbook). . E m i s s i v i t y of the P h y s i c s Handbook).  graphite  O.56  p l a t e i s i S s . 0 . 9 (Chemistry  and  - 78 -  . The r a t i o o f t h e heat r a d i a t e d , by t h e drop s u r f a c e t o t h a t r a d i a t e d by t h e g r a p h i t e base p l a t e i s  =  oSO.36  (T -Tg ) 7U5 CJN0.9 ( T - T ) 21.86 4  4  = 0.131  4  0  where  i s the S t e f a n ' s c o n s t a n t T i s t h e temperature o f t h e r a d i a t i n g body To i s the temperature o f t h e s u r f a c e t o w h i c h t h e heat i s r a d i a t i n g .  i . e . , approximately. l / 8 as much heat i s r a d i a t e d by t h e drop s u r f a c e . The  thermal c o n d u c t i v i t i e s , of the materials a r e : -  37 pure i r o n a t 800°C , O.318 j o u l e s / s e c / c m  /°C/cm  (This value  will  d e c r e a s e w i t h i n c r e a s i n g temperature) -  p y r o l y t i c graphite  " i n the b a s a l plane  direction, i.e  parallel  t o t h e s u r f a c e ^ 2 joules/sec/cm /°C/cm 2  \  t o t h e s u r f a c e ^ 0.02 joules/sec/cm /°C/cm 2  Thus, i t i s q u i t e p o s s i b l e t h a t the d i r e c t i o n o f maximum heat i s from t h e drop and a l o n g the g r a p h i t e s u r f a c e , b e i n g e m i t t e d  flow  essentially  by r a d i a t i o n . .This would account f o r the h i g h e r c o o l i n g r a t e i n t h e b a s a l area and- the r e s u l t i n g .finer.' s t r u c t u r e .  - 79 VII. 1.  BIBLIOGRAPHY K e v e r i a n , J . , T a y l o r , • R.F., and- W u l f f , J . , Am. Foundryman 2 5 , 8 5 , (1953).  . 2.  K e v e r i a n , J . and T a y l o r , H.F., T r a n s . Am. Foundrymen's Soc. 65, 212, • (1957).  3.  Milman, B.C ., •• L i t e i n o e - - P r o i z v . 6, 1 1 , ( 1 9 5 8 ) .  . 4.  White, • D-.W.G., .Canada Department o f Mines, and T e c h n i c a l Surveys I n t e r n a l . R e p o r t No.. PM-M-62-4 (May 1, 1962).  5.  U h l i g , H.H., i n American S o c i e t y f o r M e t a l s , "Metal I n t e r f a c e s " . C l e v e l a n d , Ohio, The S o c i e t y (1952), p . 312.  6.  Mehl, R . F . , i n American I n s t i t u t e o f M i n i n g , - M e t a l l u r g i c a l a n d Petroleum Engineers,- I n s t i t u t e o f M e t a l s D i v . , "The; S o l i d i f i c a t i o n o f M e t a l s a n d ' A l l o y s " , N.Y.,. A.I.M.E. (1951), p . 24.  7. - Hollomon, J . H., and T u r n b u l l , D., i n American i n s t i t u t e o f M i n i n g , M e t a l l u r g i c a l and P e t r o l e u m E n g i n e e r s , I n s t i t u t e o f M e t a l s D i v . , "The S o l i d i f i c a t i o n o f Metals and A l l o y s " , N.Y., - A.I.M.E., (1950), p.- 1. 8.  T u r n b u l l , D.,J. Chem. Phys. 2 0 , 411, (1952).  .9.  T u r n b u l l , D., and F i s h e r , J.C., J . Chem.. Phys. 17, 71,  10.  Gibbs, J . . W i l l a r d . ,  "The C o l l e c t e d Works o f J . W i l l a r d Gibbs", New  Haven,. Y a l e U n i v , , P r e s s 11. 12.  (1949).  (1948).  A l l e n , B.C. and K i n g e r y , ,W .D.,-Trans . A.I .M.E .. 215_, 3 0 , ( 1 9 5 9 ) . . K o z a k e v i t c h , P. and U r b a i n , G., Rev. Met. 5_8, 401, 517. and 9 3 1 , ( 1 9 6 l )  13.  Dyson, B.F.,. T r a n s . A.I.M.E. ,227_,. I O 9 8 ,  14.  Whalen, T . J . , Kaufman,S. M. and Humenik,,M., J r . , T r a n s . Am. Soc. .Metals 5_5_, .3, (I962) .  .15.  Koxakevitch,,P., C h a t e l , - S U r b a i n ,  (I963).  G. and Sage, M. .Rev. Met.. 52,  139,(1955). 16.  Kingery,-W.D. and Humehick,. M.j;. J r . , J . Phys.. Chem. 5_7^ ,359, (1953) • •  17.  Kaufman, S. M. and Whalen, T . J . , T r a n s . A.I.M.E. 230, 791, (1964).  18.  . M i n k o f f , . I . , T r a n s . .Am. Foundrymen's Soc. 7 0 , l8> (1-962).  .19.  Voronova, N.A., a n d - M o g i l e v t s e v , 0 . A . , , M e t a l . (USSR) ,< E n g l i s h T r a n s . J_, 459, ( I 9 6 3 ) .  .20.  B o y l e s , A., "The S t r u c t u r e o f C a s t I r o n " , C l e v e l a n d , Ohio,- American S o c i e t y f o r M e t a l s (1947).  S c i . Heat T r e a t . Metals  - 80 -  21.  Morrogh, H. and W i l l i a m s , , W.. J.,. J . I r o n S t e e l I n s t . 155,  22.  Loper,.C. R.,  69_, 583 23.  J r . , and Heine,. R.- W.,  .26.  (1947).  T r a n s . Am.. Foundrymen's Soc.  (1961). Trans.. Am.-Soc.. M e t a l s , 5_6,  . Loper, C . R. and Heine,. R.- W., :  (I963).  135  (I963).  .24. . C a r d e n , R . L . B C I R A j . , 1 0 , 325 25.  521  • AES-ASTM G r a p h i t e F l a k e C l a s s i f i c a t i o n i n Grey C a s t I r o n . D e s i g n a t i o n : ; A 2^7-47, . Garber, S., J . I r o n S t e e l I n s t . l 8 l ,  291  ASTM  (1955).  27.  .Williams,,W.  J.,- J . I r o n S t e e l I n s t . 164,  28.  .Form, G. W.  and W a l l a c e , J.. F.,.Trans. Am.  1+07  (1950),  Foundrymen's Soc. JO,  llkO  (1962). 29. 30.  Morrogh, H . T r a n s . Am.  Foundrymen's Soc. JO,  • S c h e i l , - E. and S c h o b e l , J.D.,  F o n d e r i e 19_2,  31.  Loper, C .R.,. J r . ,  32.  Morrogh, H.,  33.  S t r a u s s , H. E., Von B a l c h e l d e r , F.W.,  449 73  (1962).  (1962).  T r a n s . Am.. Foundrymen s Soc. J_0, 963 ,  BCIRA J . ,5_, 12,  655  (I962).  (1955). and S a l k o v i t z , E . I . , J . • M e t a l s  10,  249(1951). 34.  B a s h f o r t h , . F . and Adams, J.C.,  "An Attempt  t o T e s t the Theory  C a p i l l a r y A c t i o n " , London, Cambridge Univ.. Press .35. .36. .37.  (1883). 1962.  Rose, D. J.,M.A.Sc.' T h e s i s , U n i v e r s i t y o f B r i t i s h Columbia, G u e n t e r t , O.J., J . P h y s .  Chem. 37_,  4,  884  of  (I962).  . S m i t h e l l s , . C . J . , "Metals Reference Book", 3d ed. London, B u t t e r w o r t h s  ( 1 9 6 2 ) , v. 2, p. 644. 38.  Darken, S. L. and Gurry, R.W., McGraw-Hill ( 1 9 5 3 ) .  39.  E l l i o t t , J . F . , and G l e i s e r , M., "Thermochemistry f o r Steelmaking", Reading, Mass. Addison-Wesley Pub. Co. ( i 9 6 0 ) ,  40.  E l l i o t t , J . F . , ed. "The P h y s i c a l Chemistry o f S t e e l m a k i n g ; p r o c e e d i n g s " , N.Y., Technology Press, o f M.I.T. and Jonn W i l e y ( I 9 5 8 ) .  41.  American  "Physical Chemistry of Metals",  N.Y.,  I n s t i t u t e o f M i n i n g and M e t a l l u r g i c a l E n g i n e e r s , I r o n and  S t e e l D i v . " B a s i c Open Heartn Steelmaking", 2d ed. N.Y.,  A.I.M.E.  (1951). 42.  B a r t e l l , F.E. and Wooley, A.D.,  J . Am.  Chem. Soc. 5_5_, 3518  (1933).  - 81 kj>. Baes, O.F. and K e l l o g g , H.H., J . M e t a l s 5_, c43 kk.  (1953).  Harvey, J . , Clarkiy D. and E a s t a b r o o k , J.N., R o y a l A i r c r a f t E s t a b l i s h m e n t T e c h n i c a l Note No. Met. Phys. 361  (1962).  45.  D i e f e n d o r f , R . J . and S t o b e r , E.R., M e t a l s P r o g r . 8 l , 103  (I962).  kb.  Bradshaw, W. and Armstrong, J.R., " P y r o l y t i c G r a p h i t e , i t s Hign Temperature P r o p e r t i e s " , Lockheed A i r c r a f t Co. T e c h n i c a l Documentary Report No. ASD-TOR-b3-195 ( 1 9 6 3 ) .  47.  K i r k a l d y , J.S. and Purdy, G.R., P r i v a t e Communication  (1963).  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0093737/manifest

Comment

Related Items