Liquid Redistribution during Liquid‐Phase Sintering

Abstract

A simple two‐dimensional packing model, consisting of arrays of circular particles, was used to calculate the free energy changes associated with the filling of pores of different coordinations with liquid. The calculations were used to determine the equilibrium distributions of a liquid in different packing arrangements of particles. The effect of both the volume fraction of liquid and shrinkage on liquid distribution was examined. It was found that, when liquid redistribution can easily take place, the volume fraction of liquid phase, the pore size distribution of a powder compact, and the amount of densification that has occurred all influence the homogeneity of the distribution of the liquid phase. In addition, the model predicts that, as shrinkage occurs or as the volume fraction of liquid phase increases, the pores will try to fill sequentially in order of increasing size. A consequence of this sequential filling of the pores is that the radius of curvature of the liquid meniscus, and hence the driving force for liquid‐phase sintering, changes systematically as shrinkage occurs. The modeling suggests that the driving force for sintering changes in a way that depends on the initial overall pore size distribution of the particle arrangement and the way the pore size distribution changes during sintering.