Analysis of nonisothermal sintering of nanocrystalline and microscaled ceramic materials

Abstract

Sintering involves consolidation of powders under the application of heat to form solids of higher density and is often the final step in the processing of ceramic materials. The time–temperature cycles used in sintering affect the kinetics and, in turn, influence the quality of the sintered product. Considering the densification mechanisms controlled by grain boundary diffusion along with interface reaction and the grain growth mechanism, this paper presents a systematic numerical study on the sintering of nanocrystalline yttria tetragonal stabilised zirconia and microscaled α-alumina, to bring out the effects of the time–temperature cycles on their sintering behaviour. Effects of initial grain size are also examined. Based on the studies, empirical correlations are developed that relate the final grain size and the sintering time to the temperature cycle. The results serve as guidelines in the design of time–temperature cycles for the sintering of the two material systems considered.