Diamond nanoscale surface processing and tribochemical wear mechanism

Diamond is widely used in many fields due to its numerous properties. Chemical mechanical polishing can achieve ultra-smooth and low-damage surface processing of diamond. We carried out the chemical mechanical polishing experiment of single crystal diamond using W0.5 diamond powder as abrasive in aqueous H2O2. The smooth surface with roughness (Ra) values of 0.917 nm was obtained and no obvious mechanical scratches. In addition, the atom removal mechanism of Chemical mechanical polishing process on the diamond surface polished with diamond powder in aqueous H2O2 was elucidated using Reactive Force Field molecular dynamics simulations. Hydroxylation on the diamond surface plays a dual role in the removal process. The diamond structure after being oxidized is damaged so the CC bonds become weak. The C atoms on the diamond surface form stronger CC bonds with the C atoms in abrasive, then the C atoms are carried away due to the mechanical action of abrasive. This work helps understand the removal process of C atoms at the atomic scale in the CMP process and provide an effective method to realize ultra-smooth and low-damage surface processing of diamond. [Display omitted] •The smooth surface with roughness (Ra) values of 0.917 nm was obtained and no obvious mechanical scratches.•Tribochemical wear mechanism in the CMP process was elucidated using ReaxFF MD.•The oxidation of diamond surface plays a dual role in the removal of C atoms.•The C atoms in diamond substrate form stronger CC bonds with the C atoms in abrasive.