An axisymmetric model of pore-grain boundary separation

In the final stage of ceramic sintering, pores can either move with, or sep arate from, grain boundaries. The outcome is critical to the resulting cera mics. This paper studies an axisymmetric model of a single pore on a moving grain boundary. Two rate processes, grain boundary migration and surface d iffusion, are concomitant. Surfaces move to reduce the total surface and gr ain boundary energy. A finite element method is formulated to simulate the transient separation process. Using an independent method, we also obtain s teady state solutions of the pore moving with the grain boundary. The stead y state problem has multiple solutions with a surprisingly rich mathematica l structure. Finite element simulations show that some steady state solutio ns are stable, and others unstable. We find that the pore-grain boundary se paration condition is insensitive to the dihedral angle. (C) 1999 Elsevier Science Ltd. All rights reserved.