Surface evolution and material removal behavior in lapping of diamond/SiC composites

Diamond/SiC composites with superior thermal conductivity and lattice matching compared to aluminum ceramic-based composites have received tremendous attention in recent years. However, the differences in phases and potential hardness variations significantly restrict the precise component mass production. This study systematically investigates the material removal mechanisms and surface integrity of diamond/SiC composites through precision lapping, with comparative analyses of PCD composites, SiC ceramics, and CVD diamond. The effects of abrasive size (1–8 μm), processing time, and material composition on machining efficiency and surface quality were evaluated. Results show that diamond/SiC composites undergo asynchronous phase removal, similar to PCD, with 4 μm abrasives achieving optimal balance (MRR: 0.458 μm/min, Ra: 0.72 μm). Homogeneous materials (SiC, CVD diamond) exhibit linear removal patterns. SiC transitions from brittle to ductile removal, while CVD diamond undergoes wear-dominated polishing. The 8 μm abrasives increase material removal thickness but cause selective phase extraction, exposing diamond protrusions and raising surface roughness (Ra >0.86 μm). Conversely, 1 μm abrasives enable micro-plastic removal, improving surface quality (Ra: 0.41 μm) at the cost of reduced MRR (2.85 μm/min). The MRR hierarchy (SiC > Diamond/SiC > PCD > CVD) reflects the diamond phase's influence on machinability. The 4 μm abrasive emerges as the optimal choice, balancing efficiency and precision. These findings provide critical insights into parameter optimization for diamond/SiC composites, emphasizing the interplay between abrasive size, material composition, and removal mechanisms to achieve high-quality machining.