Manufacture and properties of carbon fibre-reinforced C/SiC dual matrix composites

Carbon fibre-reinforced carbon and silicon carbide dual matrix composites (C/C-SiC) were fabricated by a combination of chemical vapor infiltration with liquid silicon infiltration. The structural characteristics, mechanical performance and tribological properties of the C/C-SiC composites and their wear mechanism at different braking speeds were investigated using a QDM150 friction testing machine, SEM and x-ray energy dispersive analysis. Results indicate that the C/C-SiC composites show an increased bonding strength at the fibre/matrix interface, and the value of flexural strength and compressive strength of the C/C-SiC composites can reach 240 and 210 MPa, respectively. The friction coefficients are between 0.41 and 0.54. Wear rates are not sensitive to the brake speed and remain constant at about 0.02 cm3/MJ, and the friction coefficient is stable. Frictional films with a thickness of 1∼3 μm are formed on the worn surface of the composites upon braking. The wear mechanism changes with increased braking speed, from abrasion at 8m/s, adhesion at 12 m/s and 16m/s to fatigue and oxidation at 20 m/s and 24 m/s, respectively.