Liquid phase sintering model: Application to Si₃N₄ and WC-Co

A model for liquid phase sintering is examined. The model accounts for solid densification during sintering by particle rearrangement and contact flattening, with large pore filling and grain coarsening in the final stages of sintering. The liquid phase, which develops during heating, aids the solution and diffusion of solid atoms. The model is used to simulate the sintering of Si₃N₄. The bulk viscosity is calculated for various sintering histories. The bulk viscosity, subjected to a normalization, is shown to be approximately a unique function of density. A simplified version of the model is developed for the case where rearrangement is small. The model is applied to WC-Co and is modified to account for solution of WC in Co and rearrangement prior to binder melting. The sintering of a WC-Co turning insert is simulated and conclusions are drawn on the importance of the constitutive model in predicting shape distortions in such cases.