The High-temperature Oxidation Behavior of Hot-pressed ZrB2-SiC Composites via TEM

Abstract

The oxidation behaviors of ZrB2-30 vol% Sic composites were investigated in air, and under reducing conditions, where a temperature of 1500 oC, was applied for 10 h. A CO/CO2 mixed gas was used in the reducing conditions, with an oxygen partial pressure of 10-8 Pa. The microstructures and oxidation depths of the specimens were observed using scanning electron microscopy (SEM). The phase transformation and microstructure of the grains/grain boundaries on each layer were analyzed using transmission electron microscopy (TEM). In both cases (in air and under reducing conditions), different layers appeared with varying depths; the oxidation behaviors of ZrB2 and SiC were investigated by observing the layers using TEM. Both specimens showed similar oxidation behaviors, but their kinetics were different.