Simultaneously enhancing mechanical and tribological properties of carbon fiber composites by grafting SiC hexagonal nanopyramids for brake disk application

Extensive attention has been drawn to the development of carbon fiber composites for their application in brake disks due to the increasing demand for brake disks with high mechanical strength and better tribological properties. Herein, we design SiC hexagonal nanopyramids modified carbon/carbon (SiCNPs-C/C) composites, in which SiCNPs are radially grafted on the carbon fibers by the combined sol-gel and carbothermal reduction method, and pyrolytic carbon (PyC) matrix is deposited on nucleation sites including carbon fibers and SiCNPs by isothermal chemical vapor infiltration (ICVI). Benefiting from the special structure, SiCNPs-C/C composites exhibit superior mechanical and frictional performance. Compared with C/C composites, SiCNPs-C/C composites have 147%, 90.3%, 70.6%, and 117.9% improvement in the hardness, interlaminar shear strength, and out-of-plane and in-plane compressive strength, respectively, which is attributed to the optimized fiber/matrix (F/M) interfaces bonding and the enhanced cohesion strength of PyC matrix. In addition, the friction coefficient of SiCNPs-C/C composites increases by 25.5%, and the wear rate decreases by 38.0%. This work provides an optional design thought for the nanomaterials and enlightens the mechanical and frictional modification of composites in the field of the brakes.