A 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 co ntact flattening, with large pore filling and grain coarsening in the final stages of sintering. The liquid phase, which develops during hea ling, aids the solution and diffusion of solid atoms. The model is use d to simulate the sintering of Si3N4. The bulk viscosity is calculated for various sintering histories. The bulk viscosity, subjected to a n ormalisation, is shown to be approximately a unique function of densit y. A simplified version of the model is developed for the case where r earrangement is small. The model is applied to WC-Co and is modified t o account for solution of WC in Co and rearrangement prior to binder m elting. The sintering of a WC-Co turning insert is simulated and concl usions are drawn on the importance of the constitutive model in predic ting shape distortions in such cases. (C) 1997 Acta Metallurgica Inc.