Influence of sintering temperature, SiC particle size and Y2O3 addition on the densification, microstructure and oxidation resistance of ZrB2–SiC ceramics

The influence of sintering temperature, silicon carbide particle size (50–60 nm, 0.9 μm and 44 μm) and yttrium oxide addition on oxidation behaviour of ZrB2–SiC ceramics was investigated up to 1650 °C in static atmosphere. Weight changes were measured and the thickness of formed oxide layer was evaluated by the light and scanning electron microscopy. Results show enhanced oxidation resistance of ZrB2–SiC composites sintered at 1750 °C in spite of their lower density (∼93.2%) due to the grain growth cessation resulting in the refinement of microstructure. Similarly the oxidation resistance was also enhanced by refinement of microstructure due the submicron or nano-sized starting SiC powders. The addition of Y2O3 caused desired stabilization of cubic ZrO2 phase; nevertheless the oxidation resistance of Y2O3 doped samples was inferior in comparison to the basic material at oxidation temperatures exceeding 1500 °C.