CVD-grown SiC nanowires-reinforced SiC coating on C/C composites: Focusing on antioxidation, thermal shock and high-temperature gas erosion resistance

To improve the oxidation resistance of C/C composites, a SiCNWs-reinforced SiC (SiCNWs-SiC) coating was successfully fabricated in-situ by a simple chemical vapor deposition (CVD) process on C/C composites. Microstructural analysis revealed uniform beta-SiCNWs with diameters of 50-200 nm and lengths up to tens of micrometers. The thickness of porous SiCNWs layer is approximately 300 mu m. Elevated deposition temperatures deteriorated coating density, with optimal performance at 1373 K. The SiCNWs enhanced deposition efficiency, boosting bending strength from 107.2 MPa to 134.3 MPa and adhesion strength from 6.74 MPa to 14.18 MPa. Oxidation resistance tests at various temperatures confirmed superior performance of SiCNWs-toughened SiC coatings. Thermal shock tests showed minimal weight loss (2.5 %) after 30 cycles, outperforming pure SiC coatings (6.2 %). The 1873 K gas erosion test showed that the weight loss of the SiCNWs-SiC coated C/C samples was only 5.2 % for 53 h, while the pure CVD-SiC coated C/C composite samples broke after 19 h of gas erosion, and the weight loss of pure C/C composite samples reached as high as 38.5 % after 1.3 h of gas erosion.