Experimental Investigation of Laser Parameters Dependence of Surface Graphitization in Nanosecond Laser Ablation of Nanocrystalline Diamond.

Nanocrystalline diamond (NCD) is regarded as a highly promising composite engineering material owing to its superior mechanical properties. Surface texturing significantly enhances the surface performance of NCD. Given the unique inherent combination of hardness and brittleness in NCD, laser ablation emerges as a critical method for fabricating surface microstructures. However, the research on laser-induced surface texturing of NCD remains limited. This study experimentally investigated the characteristics of nanosecond laser-ablation-induced graphitization in NCD and provided an in-depth analysis of the laser ablation mechanism, aiming to guide the optimization of NCD surface microtexture manufacturing. Specifically, we conducted systematic nanosecond pulse laser ablation experiments on NCD samples and utilized Raman spectroscopy to qualitatively characterize the graphitization within microgrooves and across the entire ablated surface. The effects of the laser scanning speed, power, defocus level, and scanning interval on the graphitization extent and morphological characteristics were systematically investigated, identifying the single-factor optimal parameter set for maximizing graphitization. Through single-factor experimental analysis, the findings of this study provide foundational data for subsequent multivariate-coupled optimization and offer theoretical support for enhancing the surface properties of NCD through microtexturing via laser ablation.