Kinetics of Constrained‐Film Sintering

Results of shrinkage measurements on constrained and corresponding unconstrained films of materials that densify by viscous flow or solid‐state diffusion mechanisms have been presented. Constrained‐film shrinkage was measured in situ during sintering using laser reflectance; unconstrained‐film shrinkage was measured using scanning electron microscopy (SEM). Data for unconstrained films were fitted to densification kinetics expressions for the operative densification mechanism. Constrained‐film shrinkage behavior predicted by the Scherer‐Garino model, 1 using expressions that fit data for the unconstrained case, was compared to actual data for the constrained films. Data for the viscous sintering case fit the predictions made by the model well, but data for densification by solid‐state diffusion deviated from predicted behavior even when grain growth was accounted for, possibly because of pore growth caused by local densification.