Sintering of Ceramics

Abstract

The primary goal of sintering research is the controlled manipulation of microstructure. Out of the entire range of microstructures which are theoretically possible, each material system will be able to achieve only a subset of them, depending on the intrinsic material properties. Within these material constraints, the aim is to produce microstructures which enhance specific properties. Our understanding of the relationships among materials processing, microstructure, and properties is just beginning to emerge, and is producing unexpected results. For example, in a recent study of toughness in Al2O3 by Bennison and Lawn, microstructures with platy grains and a bimodal grain size distribution in undoped Al2O3 exhibited a greater resistance to crack propagation than did the more uniform microstructures in MgO-doped Al2O3 [1]. As a result of this emerging understanding, the focus of sintering science is changing from the modification of microstructures in incremental ways for correspondingly incremental improvement in properties to more effectual manipulation of microstructures to optimize properties. However, the production of the optimum microstructure will be dependent on both the material and the application and may require radically different processing routes for different materials. In this review paper, we have examined the research in sintering science over the past five years which has advanced the goal of microstructure manipulation.