Mechanisms of synergistic regulation on friction and wear performance of SUS304 stainless steel by DLC coatings and laser-textured dimple morphologies

Abstract

This study investigates the synergistic effects of diamond-like carbon (DLC) coatings and laser-processed bio-inspired microtextures in improving the tribological performance of SUS304 stainless steel. Four types of microtextures (hexagonal, rhombic, sectorial, and annular sector) were fabricated on substrate surfaces using laser processing technology, followed by deposition of DLC coatings via filtered arc vacuum coating technology (DCVA). Tribological ball-on-disk tests under varying normal loads (1, 3, 5, 7 N) revealed that surfaces combining bio-inspired microtextures with the DLC coating significantly enhanced tribological performance compared to untextured or uncoated surfaces. Specifically, the hexagonal microtexture/DLC coating surface exhibited the lowest and most stable coefficient of friction (COF) (0.17) along with minimal wear (depth 0.95 μm at a normal load of 7 N), outperforming other combinations. Finite element analysis (FEA) confirmed that this superiority stems from the symmetrical hexagonal geometry's superior ability to disperse contact stresses and inhibit crack propagation. In contrast, the rhombic microtexture/DLC coating showed pronounced stress concentration at sharp vertices under high loads, leading to increased COF fluctuations and accelerated wear. The DLC coating enhanced surface hardness, preventing material failure and maintaining microtexture integrity during sliding, while its self-lubricating properties reduced COF through graphitization and transfer film formation. These findings provide theoretical support for designing high-performance anti-friction/wear-resistant textured surfaces with DLC coatings and practical guidance for optimizing lubricated interfaces.