Enhanced tribological performance of snowflake-textured CVD diamond coatings under nanofluid lubrication

To mitigate the significant tribological degradation of chemical vapor deposition (CVD) diamond coatings under high thermal load conditions, this study proposes a synergistic approach to enhance their tribological performance through biomimetic snowflake microtextures and nanofluid lubrication. Four types of biomimetic textures were designed based on the hexagonal symmetry of snowflakes and fabricated on a YG6 cemented carbide substrate using laser ablation. Subsequently, high-performance diamond coatings were deposited onto the biomimetic snowflake-textured surfaces via CVD. Concurrently, a hybrid nanofluid lubricant was formulated using soybean oil as the base fluid, incorporating MoS 2 and MWCNT nanoparticles. Molecular dynamics (MD) simulations were further performed to provide general atomic-scale insights into the contact mechanics and interfacial mechanical response of the diamond coating under dry nano-scratching. The friction and wear tests demonstrate that the synergistic combination of snowflake textures and nanofluid lubrication reduces the friction coefficient from approximately 0.25 under untextured dry-friction conditions to 0.12, corresponding to a 52% reduction while substantially mitigating wear damage and preserving a more intact worn surface morphology. This improved tribological performance is attributed to the synergistic effects of the textures' oil-storage and stress-dispersion functions, the rolling effect of nanoparticles and the formation of a protective tribofilm. This research provides a novel strategy for optimizing and enhancing high-performance, long-life and environmentally friendly coated cutting tools.