Preparation and friction behavior of carbon fiber reinforced silicon carbide matrix composites

Carbon fiber reinforced silicon carbide matrix composites have received considerable attention because of their superior friction behavior. In this paper, carbon/silicon carbide composites were fabricated by chemical vapor infiltration. The microstructure, mechanical properties, and the friction behavior were investigated. The carbon fiber preform was fabricated with the three dimension needling method, and the infiltrated carbon/silicon carbide (C/SiC) composites exhibited excellent shear strength. The in-plane shear strength and the inter-laminar shear strength are 85 and 27 MPa, respectively. The composites show non-brittle failure behavior resulting from fiber pull-out as well as fiber cluster pull-out. The friction behavior and friction stability are significantly improved by increasing both the density and carbon content of the composites. If the density of the composite is 2.3 g cm^-3, the coefficient of friction measured is 0.23, the coefficient of friction stability (as it will be defined later on) is 0.43, and the liner wear rate is less than 9.3 μm/cycle. Moreover, the C/SiC composites demonstrate a good friction property against fading versus several braking stops. The rapid increase of friction coefficient approaching the end of braking is mainly related to the increasing of surface temperature in a short time and the enhanced adhesion and abrasion of contact conjunctions and asperities. The friction surface is covered with wear debris including flake materials and fragments of carbon fiber. The micro-cracks and grooves observed on the friction surface are significantly determined by cyclic mechanical and thermal stresses.