Definition of the parameters for the densification of ceramics by two-step solid state sintering

Abstract

The two-step sintering (TSS) process is generally used to reduce the temperature conventionally required for the sintering of ceramics and to achieve a fine microstructure, but to date a general rule concerning the TSS parameters has not yet been identified. The TSS process was successfully applied to ZnO, Al2O3 and alumina-zirconia composites obtaining a comparable density to that achieved by the conventional process and with limited grain growth. A fine‐grained microstructure was maintained, avoiding the grain boundary migration, by the right selection of the operating conditions (essentially temperatures and holding time). A comparative study of the TSS on different advanced ceramic materials, such as SiC, ZnS and ZrO2, was also proposed, mainly based on the density, the microstructure and the grain size. Moreover, a general rule concerning the process temperatures with respect to the conventional sintering was defined to obtain the same densification preventing the grain growth.

Keywords

• Two-step sintering
• Ceramics
• High density
• Grain growth
• Microstructure