Unveiling the role of remelted protrusions in the tribological behavior of TiN coatings on laser-textured substrates

During laser surface texturing (LST), remelted protrusions invariably form around the edges of surface textures. Nevertheless, their influence on the tribological behavior of overlying coatings remains inadequately characterized, with conflicting reports suggesting both beneficial and detrimental effects. To resolve this controversy, we investigated the wear performance of TiN coatings deposited on LST-processed stainless steel substrates. Three distinct sample configurations were designed for comparative analysis: as-deposited (AD), textured with preserved remelted protrusions (PR), and textured with removed remelted protrusions (RR). The mechanical properties and tribological responses of the coatings were evaluated through nanoindentation and dry reciprocating sliding tests, respectively. Results revealed that PR samples exhibited the lowest coefficient of friction (COF) during the early wear phase. However, prolonged sliding accelerated coating failure in PR samples, manifesting as a progressive increase in COF and cumulative wear volume. In contrast, RR samples effectively mitigated stress concentration and suppressed third-body abrasion, achieving the most stable COF and a 80 % ∼ 92 % reduction in wear rate. Crucially, the removal of remelted protrusions transformed the detrimental PR surface morphology into a tribologically favorable RR architecture. The findings in this work may provide helpful references for improving the tribological performance of coatings on LST-processed substrates.