Effects of the single layer CVD SiC interphases on mechanical properties of mullite fiber-reinforced mullite matrix composites fabricated via a sol–gel process

Due to the degradation of mechanical properties of mullite fiber-reinforced mullite matrix (Muf/Mu) composites with pyrocarbon (PyC) and BN interphases under an oxidation environment, single layer SiC interphases prepared by a chemical vapor deposition (CVD) process were employed. Effects of the CVD SiC interphases on mechanical properties and interfacial characteristics of Muf/Mu composites fabricated via a sol–gel process were investigated. The results show that the composites with CVD SiC interphases exhibit an obvious toughened fracture behavior, and the flexural strength is about 2.67 times that of the composites without SiC interphases. Microstructure analysis reveals that SiC interphases play a key part in protecting fibers from being damaged during the fabrication process of the composites, and weakening bonding between fibers and matrix, which are both beneficial to the improvement in mechanical properties of the composites. Flexural strength of the composites with SiC interphases after oxidation decreases by about 25.4%.