Defect suppression mechanism for laser in-situ assisted diamond cutting of reaction-bonded silicon carbide

Reaction-bonded silicon carbide (RB-SiC) is a typically hard and brittle material that is prone to a large number of machining defects in conventional processing. In this study, laser in-situ assisted diamond cutting (In-situ LAC) technique was proposed to reduce the machining defects of RB-SiC in order to achieve a mirror machined surface. Firstly, a nano-indentation study of SiC, Si phase and position at the phase boundary under a constant load of 100 mN and 300 mN was carried out. The measured hardness value data and the indentation morphology observed by scanning electron microscopy (SEM) were used to investigate the weak position of RB-SiC and analyze the causes of the defects deeply. Then In-situ LAC and ordinary cutting (OC) of RB-SiC experiments were carried out to compare the machined surface quality. The SEM analysis of the machined surface features was also used to point out the suppression effect of the machined surface defects by the laser. It was found that brittle fractures on the surface of SiC particles were suppressed, leading to a significant increase in the ductile processing regions of SiC and Si. To further investigate the effect and mechanism of laser on the suppression of subsurface defects in processing. The surface was cut by focused ion beam (FIB) and the cross-sectional morphology was observed in-situ. The extension of subsurface cracks and fracture defects were further analyzed to explore the defect suppression mechanism more comprehensively.