Ultralow Wear ZK60 Magnesium Alloy Enabled by Friction-Driven Ag/GO Nanocomposite and Zn-Segregation Induced Stratified MgO/ZnO heterolayer

ZK60 alloy inherently suffers from poor wear resistance, severely limiting its application under severe friction conditions. To improve this, a top-down strategy was employed, combining self-deposition and magnetron sputtering to construct a composite lubricating coating (Ag/GO-ZK60). Under a 15 N load for 30 min, the Ag/GO-ZK60 achieved an ultralow wear rate of 0.048 μm³ N⁻¹ μm⁻¹, corresponding to a reduction in wear of up to 94.4 % compared to that of bare ZK60. Microstructural analysis revealed that this improvement originates from the friction-driven formation of a stable Ag/GO nanocomposite, effectively preventing GO nanosheet delamination. Based on the continuous lubrication provided by GO, further friction-driven processes promoted the migration and selective oxidation of Mg and Zn, leading to the in-situ formation of a stratified and dense MgO/ZnO heterostructure beneath the Ag/GO layer. Notably, ZnO, enriched via elemental segregation and located beneath MgO, alleviates the performance mismatch between MgO and the ZK60 substrate, thereby enhancing the interfacial stability of the oxide layer and further improving the anti-wear capability.