Microstructure and mechanical property of Al2O3f/ SiO2 composites after thermal shock and fatigue tests

Abstract To meet the operating requirements of hypersonic flight vehicles in the atmosphere environment, microstructure and mechanical property of 2.5D Al2O3f/SiO2 composites by thermal shock and fatigue were investigated and compared. After 100000 fatigue tests, cracks hardly formed on the sample surface, and the interfacial bonding or fiber property was barely affected. However, after thermal shock and fatigue tests, the composites underwent typical brittle fracture and had the lowest fracture strength. The mass loss was less than 1%, and the flexural strength reached to 55.6 MPa, with the retention ratio of only 51.1%. The mechanical property degradation of the composites after tests was closely related to microstructure evolution.