Combined Effects of DLC Coating and Surface Texturing on Seizure and Friction in Reciprocating Sliding

Surface texturing is designed to improve the functional properties of machine elements by generating dimples on the surface contacted. Friction and wear resistance can also be improved by creating diamond-like carbon (DLC) coatings. These two techniques were combined to extend the lifetime of the elements and minimise friction in reciprocating conformal sliding contact. This work is functionally important for assemblies operating under high normal loads. Experiments were carried out in initially lubricated reciprocating sliding contact using an Optimol SRV 5 tribotester in the flat-on-flat configuration. The disc samples were untextured, laser textured, and DLC-coated untextured and textured. The combination of DLC coating and surface texturing caused an enhancement of the tribological performance of the sliding pair compared to that of untextured discs with and without DLC coating and textured discs without DLC coating. The DLC coating of the untextured disc caused a growth in the lifetime of a friction pair by a factor of 2.4. Seizure resistance also increased due to surface texturing of the steel disc for pit area ratios of 9 and 13%. Combining surface texturing with pit area ratios of 3 and 9% and DLC coating led to a decrease in the coefficients of friction of sliding pairs compared to only textured and coated discs. The DLC coating caused a decrease in the wear of the disc sample and reduction in wear levels of the counter samples in comparison to those of textured discs without DLC coatings.