CHEN Jing 1, LYU Xirui 2, ZHANG Jiaping 1, WANG Haoyu 2, ZHANG Jie 2
(1. AECC Shenyang Liming Aero-engine Co. Ltd, Shenyang 110043, Liaoning, China; 2. Advanced Ceramics and Composites
Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, Liaoning, China)
Abstract: SiCf/SiC composites have been fabricated by using chemical vapor infiltration (CVI) and precursor infiltration and pyrolysis (PIP) hybrid techniques. Density and porosity of the as-prepared composite are 2.5 g•cm−3 and 6%, respectively, indicating that the density of the composites can be effectively increased by using the hybrid techniques. Microstructures of the SiC fiber, interphase, CVI SiC matrix, and PIP SiC matrix were analyzed by using SEM and TEM. The SiC fiber is composed of SiC nano grains. The PyC interphase possesses layered structure without preferred orientation, while the thickness of interphase is 300 nm. The CVI SiC matrix exhibits high purity and high crystallinity. The PIP SiC matrix has higher oxygen content and is amorphous. Corrosion behavior of composite was studied in a mixed water vapor and air environment. The composite exhibits sustained weight loss due to high partial pressure of water vapor (90 vol. %) and fast gas flow rate (20 cm•s−1). The total weight loss was 2.36 mg•cm−2 after 100 h. At the initial stage of wet corrosion, the CVI SiC matrix exhibited better water vapor resistance than PIP SiC matrix.
Key words: SiCf/SiC CMC; chemical vapor infiltration; precursor infiltration and pyrolysis; microstructure; wet oxidation