Water-based lubrication of niobium nitride

Abstract Water-based lubrication has attracted wide attention as an oil-free method owing to its greener and cleaner means. However, due operating in the water environment, most moving parts would inevitably suffer from abrasion, rusting, aging problems. Developing a novel solid-water composite system with ultra-low friction wear will open new possibilities for innovative material research development. Here, we first revealed water-based behavior of high-hardness niobium nitride coating (NbN). In three-phase contact environment (water, air, NbN), oxidation hydrolytic reactions NbN result formation “colloidal solutions”, containing Nb 2 O 5 colloidal particles between tribo-pairs. Utilizing double electric layer repulsion weak shear action solution”, achieves wear; corresponding values are low 0.058 1.79 × 10 ?10 mm 3 ·N ?1 ·m , respectively. addition, other VB transition metal nitrides (VB TMNs) exhibit same feature environment; coefficients even lower than those oil-based environment. The TMNs provides reliable scheme optimizing systems without additives is expected be applied environments high humidity or insufficient coverage.