Oxidation resistance of two dimensional C/SiC composite coated with Si-B-C ceramic

Two dimensional C/SiC composite coated with Si-B-C ceramic was prepared via chemical vapor deposition (CVD). Properties and structure evolution and self-healing mechanisms of the C/SiC composite were studied after oxidation for 10 h during 700-1200 ℃. At the same time, the evolution of morphologies, composition and phase for Si-B-C ceramic were also investigated. The experimental results show that the oxidation of Si-B-C ceramic accelerates with the temperature increasing, however, the oxidation scale is shallow and no more than 7 μm. With the temperature increasing, viscosity of borosilicate glass oxidized from Si-B-C ceramic reduces but volatilization accelerates. When the temperature increases to 1200 ℃, SiO₂ crystallizes from borosilicate glass. C/SiC composite coated with Si-B-C ceramic shows an excellent oxidation resistance. Mass loss increases with temperature increasing, which is only 0.47% after oxidation for 10 h at 1200 ℃. Furthermore, the strength retention ratio is 91.6% at 1000 ℃, higher than that at other temperatures. The main mechanisms for excellent oxidation resistance of C/SiC composite is that borosilicate glass oxidized from Si-B-C ceramic can seal cracks in composite effectively.