Triggering the Interplay of sp2–sp3 Carbon-Assisted Sustained Tribofilm via Two-Dimensional Surface Modulation for Exceptional Wear Resistance of Steel Surfaces

Abstract

The relentless wear and friction of steel-based moving machinery have created ongoing challenges that hinder their industrial applications. One promising solution is the use of reduced graphene oxide (rGO) as a lubricant due to its excellent mechanical strength and promising tribological properties. However, its tendency to self-agglomerate presents a major hurdle for its practical use. This study aims to combat the restacking of rGO nanosheets by strategically intercalating self-assembled α-ZrP between the rGO layers, unlocking exceptional wear resistance in mild steel through hot-dip galvanization. The multilayer architecture of the developed coatings ensures lubrication through layer slippage during friction, while the coexistence of sp²–sp³ hybridized carbons further extends wear life, with the Zn-0.22/ZP_5@G coating exhibiting the highest wear resistance (0.277 × 10^–7 mm³ N^–1 m^–1). The as-tailored composite coating, featuring a tribolayer composed of graphitic sp² carbons, ZrO₂, Zr(PO₄)₂, and Fe₂O₃, serves as an effective dissipative medium for contact stress. The formation of diamond-like sp³ carbons induced by the tribological process further contributes to the increased hardness of the resulting tribofilm. The reduced generation of the π-conjugated system in the composite prevents the movement of electrons toward the cathodic site, while the passivation effect induced by the composite effectively inhibits electrolyte permeation, resulting in substantial corrosion resistance. The exemplary wear resistance with remarkable anticorrosion performance achieved in this study offers significant improvement in the realm of hard coatings for mechanical applications, including moving machinery and manufacturing. Hence, the system can find effective use in such industries following the completion of relevant case studies.