Oxidation behavior of CVI, MSI and CVI+MSI C/SiC composites
(1. Guangzhou Research Institute of Nonferrous Metals, Guangzhou 510650, China;
2. State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China)
2. State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China)
Abstract: The oxidation behavior of chemical vapor infiltration (CVI), molten silicon infiltration (MSI) and CVI+MSI C/SiC composites at 500−1 400 ℃ was studied. The oxidation below 900 ℃ increased successively for CVI, CVI+MSI and MSI composites. However, the oxidation of CVI composite above 1 000 ℃ was much faster than that of MSI and CVI+MSI composites. As active carbon atoms produced by siliconization of fibers during MSI process were oxidized first and decreased initial oxidation temperature. The initial oxidation temperature of MSI, MSI+CVI and CVI composites was 526, 552 and 710 ℃, respectively. New active carbon atoms were generated due to the breaking of 2D molecular chains during oxidation, so the activation energy of three C/SiC composites was decreased gradually at 500−800 ℃ with oxidation process, exhibiting a self-catalytic characteristic.
Key words: chemical vapor infiltration (CVI); molten silicon infiltration (MSI); C/SiC composites; oxidation