Preparation and tribological properties of C/C–SiC brake composites modified by in situ grown carbon nanofibers

Abstract

Present results and experience show that currently used brake pads for carbon-based or conventional systems limits the broader use of C/C–SiC composites. In this work, the C/C–SiC brake composites were modified by in situ grown carbon nanofibers (CNFs) on carbon fibers surface, pyrolytic carbon (PyC) matrix was fabricated by chemical vapor infiltration, and SiC ceramic matrix was fabricated by liquid silicon infiltration. The effects of CNFs on the tribological properties and mechanisms of the friction pairs of C/C–SiC composites mating with metallic counterpart were investigated. The results indicated that the density and open porosity of the materials were 2.18 g/cm3 and 6.3%, respectively. Due to the growth of CNFs, a better bonding interface formed between PyC and carbon fibers, and leaded to excellent tribological characteristics of C/C–SiC composites. Compared to the C/C–SiC composites without CNFs modification, the C/C–SiC composites in this work showed higher static friction coefficient (0.38) and dynamic friction coefficient (0.29). As a result the composites braked steadily, with lower temperature on friction subsurface (396 °C), and the linear wear rates of C/C–SiC with CNFs modification and counterpart were 2.23 μm cycle−1 and 1.24 μm cycle−1, respectively, which were superior in wear resistance. The brake process of the friction pairs of C/C–SiC with CNFs modification mating with metallic counterpart could be divided into three stages, and the main wear mechanisms consisted of grain abrasion, fatigue wear, adhesive wear and oxidation abrasion.