Hot-Pressed ZrB2-SiC Ceramics with VC Addition: Chemical Reactions, Microstructures, and Mechanical Properties

Alterable roles of VC addition on the densification, microstructure development, and mechanical properties of the ZrB2-SiC ultrahigh temperature ceramics (UHTCs) were comprehensively investigated based on utilizing the thermodynamic analysis and experimental results. Chemical reactions of VC with the inevitably existed oxide (ZrO2) impurity on the particle surfaces of the ZrB2 starting powder, or with the ZrB2 matrix phase could be controlled by adjusting the atmospheres during hot pressing. Different chemical reactions during hot pressing also resulted in much different material microstructures and then different material properties. Benefiting the VC addition and proper sintering atmosphere, refined grain size of ZrB2 and improved mechanical properties were developed in ZrB2-SiC systems. By properly controlling these reactions, the microstructures and mechanical properties of ZrB2-SiC based UHTCs could be tailored.