Shrinkage and disappearance of a closed pore in the sintering of particle cluster

The shrinkage of a closed pore in the sintering of a particle cluster was analyzed. The shrinkage rate was proportional to the sintering stress, and inversely proportional to the macroscopic viscosity. The sintering stress was determined as a function of the pore volume, the dihedral angle, and the pore coordination number. The macroscopic viscosity was expressed as a function of pore volume in sintering by viscous flow, lattice diffusion, interface-controlled lattice diffusion, or grain boundary diffusion. The pore shrinkage was simulated using the Surface Evolver program in three dimensions. As the large pore shrank, the pore coordination number decreased gradually. This topological transformation of the pore increased the sintering stress and promoted densification.