High-temperature properties of Al 2 O 3 /SiO 2 composites

In this study, Al 2 O 3 fiber-reinforced silica matrix composites were fabricated by traditional sol–gel process. To study the mechanical properties of Al 2 O 3 /SiO 2 composites under high-temperature environment and after high-temperature treatment, the tensile strength and fracture behavior of it under high temperatures were investigated, and their flexural strength after heat treatment at various temperatures was also examined. Our results indicated that the tensile strength of original composites was 85.6 MPa, and that at 1000, 1100, 1200, and 1300 °C was 77.5, 62.5, 52.5, and 40.2 MPa, respectively. The flexural strength of original composites was 78.1 MPa, and that after heat treatment at 1100, 1300, and 1500 °C was 45.5, 40.5, and 27.9 MPa, respectively. The composites exhibited ductile fracture after tensile tests, and still maintain high tensile strength of about 50% even at 1300 °C. What is more, the composites exhibited brittle fracture after heat treatment, with no formation of new phase after heat treatment. In conclusion, our findings suggested that Al 2 O 3 /SiO 2 composites display outstanding high-temperature properties.