Fabrication and Thermal Stability of Continuous Carbon Fiber Reinforced Alumina Matrix Composites via Sol–Gel Process

In this paper, continuous carbon fiber reinforced alumina matrix (C/Al 2 O 3 ) composites were fabricated through the “sol infiltration-drying-heat treatment” route. In the composites, nano aluminum sol with high solid content was elected as raw material. Similarly, carbon fiber cloth preform with a laminated-stitched structure was chosen for reinforcement. The preparation process and high-temperature failure behavior of the composites under an inert atmosphere were studied emphatically. The results showed that the porosity of C/Al 2 O 3 composites prepared by 28 cycles was 16.6%, and the three-point bending strength was 208.5 MPa at room temperature. The fracture toughness of composites was 8.1 MPa · m 1/2 , which was 102.5% higher than that of alumina ceramic. After 1 h high-temperature test at 1400 °C and 1600 °C under Ar, the strength retention rate of C/Al 2 O 3 composites was 84.4% and 73.0%, respectively. SEM indicated the thermal mismatch between matrix and fibers contributed to the reduction in mechanical properties of C/Al 2 O 3 composites.