Oxidation of ZrC-30 vol% SiC composite in air from low to ultrahigh temperature

Oxidation of ZrC-30 vol.% SiC is investigated in air using furnace and oxyacetylene torch. The microstructure and phase composition of oxide scales are analyzed via SEM, XRD, and Raman. At 800 and 1100 degrees C, SiC is embedded in the porous and cracked ZrO2 scales, which have a single-layer structure and are almost non-protective. At 1300 and 1500 degrees C, the protective effect of oxide scales is enhanced by the formed SiO2. The scales consist of two subscales, outer and inner layers, during oxidation at 1300 degrees C for >= 1 h, and 1500 degrees C for >= 15 min. The growth kinetics of both layers is analyzed. At similar to 1700 degrees C, a new layer is observed between the outer and inner layers, which should contain less carbon than the inner layer. At similar to 2100 degrees C, the oxide scale is porous and contains many big holes. This scale shows a single-layer structure, which mainly consists of ZrO2. (C) 2011 Elsevier Ltd. All rights reserved.