Study of Wear and Corrosion Resistance of Cold Sprayed TC4 Coating on the Surface of Mg-Li Alloy

Abstract

Mg-Li alloys have achieved vital applications in aerospace, automotive, and 3C fields for their prominent properties. However, the Mg-Li alloy exhibits poor corrosion and wear resistance due to the high activity of Mg and Li elements and low hardness of Mg. Accordingly, TC4 alloy coating was prepared on the surface of Mg-Li alloy using the cold spray technique to enhance the surface properties. Moreover, the microstructure, microhardness, tribological properties, and corrosion resistance of the coating were systematically investigated. As indicated by the results, the interface between the coating and the Mg-Li alloy substrate was mechanical bonding without significant defects. Several pores exist in the cold sprayed TC4 coating for its high elasticity, toughness, and passivation, resulting in a porosity of 4.3%. The microhardness of the cold sprayed TC4 coating reached 296.3 HV, marking a notable increase in comparison with the substrate. The TC4 alloy coating has better wear resistance than the Mg-Li alloy substrate. The wear volume of the cold sprayed TC4 alloy only accounted for 38% of that of Mg-Li alloy. Abrasive wear was the major wear mechanism of the TC4 alloy coating. In electrochemical tests, the corrosion current density of the TC4 alloy coating (1.426 × 10−5 A/cm2) was two orders of magnitude lower than that of the magnesium-lithium alloy substrate (1.008 × 10−3 A/cm2), and the corrosion potential of the TC4 alloy coating was higher, which indicates that the coating has excellent corrosion resistance.