Influence of the fiber orientation on 3D C/C–SiC composite material and its formation mechanism of the machining surface

Carbon/Carbon (C/C)–SiC composite materials attained much attention due to its unique properties like immense thermal conductivity, high corrosion, and abrasive resistance. Few scholars have systematically studied the grinding machinability of 3D C/C–SiC composite material. In this paper, the grinding experiment of 3D C/C–SiC composite material was carried out with a resin-bonded diamond grinding wheel. The effect of machining conditions on the grinding force, micromorphology, surface quality, and residual stress was studied, and the material removal mechanism was analyzed in-depth aimed at the three typical fiber orientations. The result shows that the surface roughness of different fiber areas follows the order: 90° fiber > 0° fiber > Normal fiber. The fiber’s orientation showed a significant effect on the mechanism of material removal. The residual thermal stress of C/C–SiC composite material increases from 32.25 to 207.43 MPa during the grinding process. Polishing the ground surface not only can remove the crack layer and residual stress layer but also can introduce residual compressive stress layer, which can effectively enhance the material strength. The 3D C/C–SiC composite material removal process is distinct from the composite material 2D C/C–SiC and the traditional brittle material. The main removal of C/C–SiC composite material is recognized as brittle fracture mode. Because of the different mechanical properties of carbon fiber, SiC matrix, and the pyrocarbon interface, the damage of material during grinding is asynchronous. The present work provides a comprehensive understanding for processing 3D C/C–SiC composite material parts with high quality.