Investigation on influence of polishing disc materials in UV-catalytic polishing of single crystal diamond

The effects of three materials (Fe, SiO2, Al2O3) on the tribological behavior and material removal process of single crystal diamond (SCD) in a UV-catalyzed environment were investigated through ball-on-disc friction and wear experiments, as well as CMP experiments. The results indicate that the material removal rate (MRR) of SCD increases with the hardness of the polishing disc material. However, the surface roughness Ra is influenced by the synergistic effect of both chemical and mechanical actions. Strong chemical action leads to C-O corrosion on the surface, while strong mechanical action causes sp2 damage to surface C atoms. When using Al2O3 discs, the MRR is the highest, reaching 713.5 nm/h, while SiO2 discs result in a smooth surface with a surface roughness Ra of 0.26 nm. Therefore, the SCD can be rough polished with Al2O3 discs first and then fine polished with SiO2 discs to achieve a high material removal rate and superior surface quality simultaneously.