Ceramic and Metal Sintering: Mechanisms of Material Transport and Density-Limiting Characteristics

Abstract

Professor Lenel’s paper [1] covered the material on the derivation of sintering models [2,3], the features which distinguish different mechanisms of material transport, and the behavior of some metallic systems where the applicability of specific models has been demonstrated. It has been shown that a diffusion mechanism is generally operative in metal sintering. In this paper further data are presented showing that diffusion sintering occurs in ceramics. The main purpose is to discuss the similarities and differences in the behaviors of metals and ceramics considering solid-phase sintering, liquid-phase sintering, boundary diffusion effects observed in several systems, and some recent results on the mechanisms of material transport during hot-pressing. These are the various mixtures of systems which are sintered to fabricate materials of controlled density and grain size. We wish to understand what controls the density limit, what controls grain growth, and how these are interrelated. The interrelations are understandable if the mechanisms of matter transport that govern the kinetics of density change and of grain growth are known; this provides the reason for the emphasis on the mechanism of material transport in sintering studies.