Thermal shock resistance of Al2O3/SiO2 composites by sol-gel

Abstract In this paper, the SiO2 ceramic matrix composites were reinforced by the two-dimensional (2D) braided Al2O3 fibers by sol-gel. To develop the high performance aeroengine with excellent resistance to thermal shock for advanced aerospace application, two different thermal shock temperatures (1100 °C and 1300 °C) and three different thermal shock cycles (10, 20 and 30 cycles) were tested and compared in this paper; besides, the thermal shock resistance of Al2O3/SiO2 composites was investigated in air. Our results suggested that, the flexural strength of the untreated composites was 78.157 MPa, while the residual strength of Al2O3/SiO2 composites under diverse thermal shock cycles and temperatures had accounted for about 95% and 50% of the untreated composites, respectively. Meanwhile, the density and porosity of the composites were gradually increased with the increase in test temperature. Moreover, the changes in fracture morphology and micro-structural evolution of the composites were also observed. Our observations indicated that, the fracture morphology of the composites mainly exhibited ductile fracture at the thermal shock temperature of 1100 °C, whereas brittle fracture at the thermal shock temperature of 1300 °C. Additionally, Al2O3/SiO2 composites belonged to the Oxide/Oxide CMCs, so no new phase was formed after thermal shock tests. Above all, findings of this paper showed that Al2O3/SiO2 composites had displayed outstanding thermal shock resistance.