Microstructure and oxidation protection of a MoSi2/SiO2-B2O3-Al2O3 coating for SiC-coated carbon/carbon composites

Abstract A MoSi 2 /SiO 2 -B 2 O 3 -Al 2 O 3 double layer coating was prepared on the surface of SiC-coated carbon/carbon (C/C) composites by pulse arc discharge deposition (PADD). The phase compositions and morphology were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The oxidation resistance and thermal cycling property of the multi-layer coating were investigated. Results indicate that the multi-layer coating exhibit excellent anti-oxidation property. The MoSi 2 /SiO 2 -B 2 O 3 -Al 2 O 3 coating can effectively protect C/C composites from oxidation in air at 1073 K for 200 h with negligible weight loss and 1773 K for 200 h with a weight loss of 0.7%. Meanwhile, the coating can endure the thermal cycling for 50 cycles between 1773 K and room temperature (298 K). The formation of B 2 O 3 glass phase at low temperature and borosilicate glass at high temperature are the main reasons for the good oxidation resistance of the coating.