C_f/SiC composite is regarded as promising frictional materials for advanced high-speed railway and civil aircraft. Severe damages can occur in C_f/SiC composite during mechanical machining; however, their potential impact on the friction performances is unclear. This study conducted comparative reciprocating friction tests using ground and unprocessed C_f/SiC composite, and clarified the role of grinding-induced damages in tribological and wear behavior. It was revealed that the coefficient of friction (COF) gradually decreased and then remained stable around 0.38 during friction; various fracture damages, including fiber fracture and pulling-out, matrix cracking, and interface debonding, were observed in C_f/SiC composite after grinding, resulting in a higher COF (0.73) but shorter decreasing period compared with unprocessed materials. These damages were removed with the continuous wear of surface materials, and a friction film with oxides was rapidly formed due to the micro wear debris adhering, which played the role of lubrication and antifriction. Furthermore, the wear mechanism of C_f/SiC composite underwent a transition from abrasive wear to attrition wear and adhesion wear during the entire friction process, and the existence of grinding-induced damages significantly accelerated the transition.

To improve the application and service of C_f/SiC composites as advanced high-temperature structural materials, it is critical to achieve their high-efficiency and low-damage machining. In this study, the laser-ablating assisted grinding (LAAG) method was presented, and the connection of damage behavior and removal mechanism with laser and grinding processes was revealed. The results demonstrated that the surface of C_f/SiC composites after laser ablation was covered with a substantial number of loose oxides primarily composed of SiO₂. Laser ablating process, grinding parameter and abrasive belt selection have a significant impact on the machining results. By fabricating an ablative layer with small laser scanning spacing, and selecting small abrasive grains and feed rate during grinding, the machinability was improved and a relatively lower-damage grinding surface could be obtained. Under the optimal combination of process parameters, the grinding force and temperature of LAAG could be reduced by up to 85% and 35%, respectively. In this case, the subsurface damage of C_f/SiC composites occurred only in the form of microcracks rather large-scale fracture, and the formation of interface debonding and matrix cracking was significantly reduced. Furthermore, the grinding chips were mostly shown as micron-sized powders, indicating that the removal mechanism of C_f/SiC composites was primarily the micro-fractured and attrition wear of laser-ablated layer.