Effect of fiber orientation on surface characteristics of C/SiC composites by laser-assisted machining

In this paper, the characteristics and mechanism of laser-assisted machining (LAM) of C/SiC composites with different fiber orientations (0 degrees, 45 degrees, 90 degrees, 135 degrees) are studied. For the purpose of this study, a series of LAM experiments have been carried out and supported by a comparative analysis over the conventional machining (CM). Furthermore, the effect of fiber orientation on surface morphology, roughness, and sub-surface damage was explored. It is found that the surface quality of the workpiece treated by LAM is better than that of CM, and a lower surface roughness Ra value is obtained. It is shown that depending on different fiber orientations, the surface roughness decreases in different degrees. The roughness at 90 degrees fiber orientation witnesses the maximum reduction, followed by 0 degrees and 45 degrees fiber orientation, and the roughness at 135 degrees fiber orientation undergoes the slightest reduction. Moreover, surface micro-defects under LAM are significantly reduced, and fiber fractures are tidier. On the other hand, the matrix is mixed with fiber debris under high temperatures and sticks to the machined surface, filling and repairing surface pits and holes and hence improving the processed surface quality. These results provide new guidance for improving the machining quality of C/SiC composites.