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The relationship of interfacial energy to graphite shape in the Fe-C system.

University of British Columbia

The relationship between surface energy and precipitated graphite form in Fe-C alloys was examined in this thesis.Surface tension and contact angle data were obtained using the sessile drop technique. Carbon saturated, puron iron crucibles were melted on pyrolytic graphite, the effect of time, temperature (1500-1600°C) and additions of Ni, Mn, S or Ce being examined. The graphite form was established by metallographic examination. An average ƔLV of 1152 dynes/cm was determined for the Fe-C alloys (4.6% C) at approximately 1300°C, the average contact angle being 128°. No significant change occurred with additions of Ni ( 0.85%) and Mn ( 1.65%). Additions of S lowered the surface energy and increased the equilibrium contact angle. Ce additions had a similar effect although a direct comparison with the Fe-C alloys could not be made as different temperatures were used. However, the interfacial energy difference apparently increased with increasing Ce content, implying an adsorption of Ce to the graphite-melt interface. The change from the flake to the nodular form was accomplished in several transition stages, the interfacial energy differences being small, indicating a marked dependence on the solidification and growth conditions.

Text

2011-09-29

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http://hdl.handle.net/2429/37689

Metals and Materials Engineering

University of British Columbia

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