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

Oxidation of ZrC-30vol.% 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°C, SiC is embedded in the porous and cracked ZrO ₂ scales, which have a single-layer structure and are almost non-protective. At 1300 and 1500°C, the protective effect of oxide scales is enhanced by the formed SiO ₂. The scales consist of two subscales, outer and inner layers, during oxidation at 1300°C for ≥1h, and 1500°C for ≥15min. The growth kinetics of both layers is analyzed. At ∼1700°C, a new layer is observed between the outer and inner layers, which should contain less carbon than the inner layer. At ∼2100°C, the oxide scale is porous and contains many big holes. This scale shows a single-layer structure, which mainly consists of ZrO ₂.