Coarsening in a viscous matrix

When a viscous material is three-dimensionally constrained (as when a gel or slurry of glass is infiltrated into the interstices of a particle packing), heat treatment leads to coarsening of the pore-size distribution, rather than densification. The smaller pores generate greater capillary pressure; therefore, they shrink and force the larger pores to expand. In this article, the kinetics of coarsening are analyzed, and sample calculations are performed for a body with a lognormal distribution of pore sizes.