Hot-Pressed ZrB_2-SiC Ceramics with VC Addition: Chemical Reactions,Microstructures, and Mechanical Properties

摘要

Alterable roles of VC addition on the densification, microstruc-ture development, and mechanical properties of the ZrB_2-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 (ZrO_2) impurity on the particle surfaces of the ZrB_2 starting powder, or with the ZrB_2 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 ZrB_2 and improved mechanical properties were developed in ZrB_2-SiC systems. By properly controlling these reactions, the micro-structures and mechanical properties of ZrB_2-SiC based UHTCs could be tailored.