High-Temperature Oxidation Behavior of (Ti0.8Nb0.2)C–10 wt% SiC Composite Ceramics with Enhanced Oxidation Resistance in Air

In this study, 10 wt% SiC-mixed (Ti 0.8 Nb 0.2 )C composite ceramics (TNC-10) are prepared using the spark plasma sintering method, and their oxidation behavior is examined from 1000 °C–1400 °C in air. According to the isothermal oxidation experiments, TNC-10 samples exhibit superior oxidation resistance compared to single-phase (Ti 0.8 Nb 0.2 )C ceramics and newly developed multicomponent high-entropy carbide ceramics. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy analyses show that SiC effectively delays the outward diffusion of Nb and reduces the relative ratios of Nb and Ti in the oxides, which increase the content of (Ti δ Nb 1− δ )O 2 in the oxide layer. Furthermore, the density of the oxide layer improves due to the filling of defects by SiO 2 microparticles, which effectively impede the diffusion of oxygen. The enhanced oxidation resistance is primarily attributed to the low oxygen permeability structure of the dense oxide layer.