UBC Theses and Dissertations
Electrical resistivity of hot-pressed compacts Ramanan, Thiagarajan
An attempt has been made to study the change in the electrical resistivity of a powder compact during the initial stages of hot-pressing. Theoretical models have been formulated on the basis of plastic deformation of spheres in a compact. The resistivity change during densification has been derived for various packing arrangements. For small deformation of spheres, the final equation is [formula omitted] and the more generalized equation for larger deformation is [formula omitted] where ơm and ơc are the conductivities of a compact of spheres having a relative density D, and at the theoretical density (D = 1), respectively. Do is the initial relative density of the compact before deformation. α is a constant depending on geometry and R is the radius of spheres at any stage of deformation in arbitrary units. The derived relationship was tested by: (a) measuring the electrical resistivity as a function of density during hot-pressing of compacts of glass spheres, (b) measuring the electrical resistivity of different compacts of nickel spheres at room temperature, and (c) comparing previous resistivity data with the theoretical equation.
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