Comparative study on structure, corrosion properties and tribological behavior of pure Zn and different Zn-Ni alloy coatings

Zn and Zn-Ni alloy coatings were electrodeposited from sulfate based electrolytes. The effect of alloys Ni content on morphology, microstructure, corrosion properties, microhardness and tribological behavior of these coatings were investigated and the results were compared with Zn film. According to X-ray diffraction patterns, different intermediate phases (η-Ni3Zn22, γ-Ni5Zn21, β-Zn-Ni) were formed by increasing the coatings Ni content from 11 to 17 wt%. Polarization and EIS results revealed that all the alloy coatings had better corrosion resistance than the Zn film. Zn-14 wt%Ni coating had the least corrosion current density and maximum polarization resistance between all the samples. Microhardness of the coatings was improved by increasing their Ni percentage to 17%. However, Zn-14 wt%Ni coating had the lowest wear loss and friction coefficient, while Zn film had the worst wear resistance between all the coatings.