Single diamond grit scratching of unidirectional C_f/SiC composite: Mechanical responses and fracture mechanism

C-f/SiC composite is a typical heterogeneous brittle composite material, its precision machining has always been affected by the complicated removal mechanism. This paper conducted a single diamond grit scratching experiment on the unidirectional C-f/SiC composite to investigate the material's mechanical response under different loads and scratching depths. The scratching force and acoustic emission signals were measured to reveal the removal characteristics. The scratching removal behavior of SiC matrix and carbon fibers in the two-phase component of unidirectional C-f/SiC composites was analyzed based on the fracture size and fiber fracture morphology. The results show that the parallel scratching process could produce a better strength resistance with mild rupture features of fiber extrusion fracture and shear removal. While the perpendicular scratching process is generally resulting in crack propagation along the fiber direction with interface failure and bending fracture failure along the moving direction.