High-temperature mechanical properties of thermal barrier coated SiC/SiC composites by PIP process with a new precursor polymer

Three dimensional (3D) braided silicon carbide (SiC) fiber reinforced SiC matrix (SiC/SiC) composites were fabricated by precursor impregnation and pyrolysis (PIP) process. Liquid polyvinylcarbosilane (LPVCS) with active SiH and -CHCH2 groups was adopted as the SiC matrix precursor. SiC/SiC composites were coated with environmental barrier coatings (EBCs) to enhance their durability and air oxidation resistance at high temperature. The fabricated SiC/SiC composites exhibited superior density and high-temperature mechanical properties. Bulk density and porosity of the composites were 2.16 g/cm3 and 6.7%, respectively. The tensile strength of the composites was 339.7 MPa at 1300 °C. Tension-tension fatigue tests were conducted at frequency of 1 Hz ranging from 40 to 120 MPa at 1300 °C in air. Fatigue life could be divided into four regimes, low cycle regime, stable-state regime, high cycle regime and run-out regime. The microstructure as well as damage and failure mechanisms of the composites were investigated.