A ZrB2-SiC(Al) Coating with Improved Oxidation Resistance for C/C Composites: Design, Experimental Verification and Oxidation Mechanism

In order to improve the oxidation resistance of ZrB2-SiC coating, Al2O3 dopant was introduced to modify the structure of oxygen-inhibiting glassy layer. Al2O3-doped ZrB2-SiC (ZrB2-SiC(Al)) coating was designed, optimized and prepared by spark plasma sintering. Microstructure evolution and oxidation mechanism were investigated by experiment and first-principles calculation. Compared with ZrB2-SiC coating, ZrB2-SiC(Al) coating showed a significantly improved oxidation resistance. Characterization and calculation results indicated that the superior oxidation resistance could be ascribed to the higher bridging oxygen content, the improved stability of glass structure, and the decreased oxygen diffusion rate of glassy layer due to the increased solubility of ZrO2.