Prediction and experimental investigation of depth of subsurface damage in semi-consolidated abrasive grinding of cleavable gallium oxide crystals

This paper presents a predictive model of subsurface damage depth hSSD and surface roughness in semi-consolidated abrasive grinding based on indentation fracture theory to rapidly and non-destructively detect subsurface damage of the workpiece. To verify the accuracy of the proposed model, cross-sectional microscopy was used to detect subsurface damage along the (100) and (010) crystal lographic planes in grinding of gallium oxide. In addition, the effects of grinding method, abrasive particle size, grinding pressure, and grinding disc speed on the damage along the (100) and (010) planes were analyzed. The results show a nonlinear relationship between the depth of the gallium oxide subsurface damage and surface roughness generated by semi-consolidated abrasive grinding. Under the same grinding conditions, the damage layer depth in semi-consolidated abrasive grinding is lower than in free abrasive grinding. When the same grinding method is used, the subsurface damage depth is greater along the (100) plane than along the (010) plane under the same grinding conditions. When the abrasive particle size is decreased from W14 to W3, the depth of the subsurface damage layer is reduced by 30% in semi-consolidated abrasive grinding. Reducing the grinding pressure can reduce the amount of subsurface damage, and the speed of the grinding disc also affects the subsurface damage of gallium oxide. The subsurface damage depth has little effect. After optimizing the grinding parameters, the surface roughness of gallium oxide along the (100) and (010) planes was 23 nm and 12 nm, respectively, and hSSD was 2.9 μm and 2.1 μm, respectively. The proposed model of the relationship between subsurface damage depth and surface roughness can be used to achieve rapid, accurate, and non-destructive detection of the depth of subsurface damage and provides technical guidance for subsequent grinding and polishing processes.