Multi-pass scratch properties of titanium and vanadium-doped diamond-like carbon coatings applied on commercially pure titanium under different tribological environments: Dry, bio-aqueous, and lubricated conditions

This study examined the influence of titanium (Ti) and vanadium (V) doping on the mechanical performance and scratch resistance of diamond-like carbon (DLC) coatings applied to commercially pure titanium (Cp-Ti) substrates. The coatings were produced using physical vapor deposition (PVD), and scratch tests were performed under dry, Ringer’s solution, and lubricated conditions. Structural and mechanical characteristics were assessed via X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), and microhardness tests. Surface hardness, residual stress, and coating thickness showed notable changes with Ti and V incorporation compared to untreated Cp-Ti. Scratch resistance varied with environment, with lubricated conditions offering the highest resistance and producing narrower scratches than those in Ringer’s solution. These outcomes were linked to the uniform carbide distribution and increased compressive residual stresses in the doped coatings.