Laser ablation and surface modification-assisted polishing of polycrystalline diamond : from mechanisms of ablation and phase transition to high-efficiency processing

Abstract

Polycrystalline diamond (PCD) exhibits exceptional thermal and electronic properties, making it a critical material for high-power and high-performance electronic devices. However, its extreme hardness, chemical inertness, and variable grain orientation pose significant challenges to efficient polishing. To address this issue, this study proposes a laser ablation and surface modification-assisted polishing method, based on a combined high-fluence and low-fluence laser scanning strategy. The influence of laser parameters on surface morphology and phase composition is systematically investigated, and the effectiveness of the hybrid process is comprehensively validated. The results demonstrate that high-fluence vertical-incidence laser ablation significantly reduces surface roughness through a self-planarization mechanism, arising from the laser energy modulation by surface topography and the material's intrinsic brittleness. The subsequent low-fluence laser scanning induces substantial phase transitions under combined thermal and stress effects, resulting in a modified layer with reduced hardness and enhanced plastic deformation capacity. In the final mechanical polishing stage, the surface with the combined laser scanning strategy achieves a roughness of 0.33 μm after 60 min of polishing. The maximum material removal rate reaches 24.7 μm/h, which is 2.1 times that of the pristine sample. This is attributed to the synergistic effect of laser-induced planarization and surface modification in enhancing polishing performance. These findings offer valuable insights into the interaction between laser radiation and diamond materials, and present a promising hybrid strategy for high-efficiency PCD processing.