In-situ Synthesis and Oxidation Resistance of Sialon/SiC Composite Ceramics Applied as Solar Absorber

Sialon/SiC composites were synthesized in situ from SiC, α-Si3N4, AlN, calcined bauxite, quartz and Y2O3 via layered buried sintering at different temperatures (1 540–1 640 °C). The results showed that the O’-sialon/SiC sample with 60 wt% silicon carbide sintered at 1 600 °C exhibited excellent mechanical properties, with apparent porosity of 16.01%, bulk density of 2.06 g·cm−3, bending strength of 52.63 MPa, and thermal expansion coefficient of 5.83×10−6 °C−1. The oxide film formed on the surface was linked closely to O’-sialon, so the oxide film was not easily broken. After 100 h oxidization, the sample surface was smoother and denser, with oxidation weight gain rate 23.6 mg/cm2 and oxidation rate constant 2.0 mg2·cm−4·h−1. Therefore, the sample had the excellent high-temperature oxidation resistance. It was confirmed that the in-situ sialon/SiC composites could be a promising candidate for solar absorber owing to its high-temperature oxidation resistance.