Gold film suppresses ablation damage of CVD polycrystalline diamond by sub-nanosecond pulsed laser processing: Experimental and theoretical investigation

By applying the gold film to the surface of CVD polycrystalline diamond, the ablation damage caused by sub-nanosecond pulsed laser could be significantly reduced, which held considerable importance for enhancing the efficiency of diamond removal in laser processing technologies. This study investigated the effects of average laser power, scanning speed, defocusing amount and scanning pass on the surface morphology of the gold film. The results demonstrated that the gold film consistently mitigated ablation damage across various laser parameters. Notably, the gold film reduced the ablation threshold and minimized the formation of cracks, pits and deposition residues. Furthermore, the gold film extended the range of optimal laser parameters and offered greater flexibility for suppressing damage and improving processing quality through parameter adjustments. Additionally, a model was developed to simulate the temperature field of diamond during the duration of single pulse. The energy transfer process during sub-nanosecond pulsed laser irradiation on the gold-coated and uncoated diamond was simulated and the mechanism of gold film inhibiting ablation damage was clarified. Finally, Raman spectra and surface morphology were employed to investigate the effects of laser parameters on the phase transition structure and machining process.