| A formula describing the progress of shrinkage of a powder compact has been derived for the case of sintering of nonspherical particles as follows: f=constant(t/T)^m exp[-mQ_v/(RT)] Here f is the ratio of change in a linear dimension of a powder compact during sintering to the original dimension, and t, T, R, Q_v and m are the sintering time, the sintering temperature on the absolute scale, the gas constant, the activation energy for the volume diffusion and the geometric factor respectively. The shrinkage of tantalum powder compacts composed of powders with the various shapes has been analyzed based on the formula. The activation energy for the volume diffusion of tantalum has been evaluated to be about 80,000 cal per mole. The various expressions on shrinkage of a powder compact have been discussed based on the formula. |
|
