Influence of atmospheric pressure plasma modification on surface properties of aluminum alloy substrate and its interfacial adhesion strength with electrodeposited nickel coating

Abstract

In the domain of electrodeposited coating applications, the interfacial bonding strength between substrate and Ni-based coatings plays a critical role in determining coating quality and service life. This study investigates the impact of surface physicochemical properties of aluminum alloys on the interfacial bonding strength with electrodeposited nickel, employing a nitrogen/air atmospheric pressure plasma operating at 10 W to modify the substrate surface. The surface microstructure of the substrate remains unaltered following plasma treatment, as evidenced by SEM and AFM images. However, XPS and FTIR-ATR analyses reveal a reduction in carbon content and an increase in polar hydrophilic functional groups, imparting hydrophilicity to the substrate surface. Notably, air plasma treatment proves more effective in modifying the aluminum alloy substrate compared to nitrogen plasma, leading to a super-hydrophilic state with a contact angle of 4.06°. Nano-scratch tests demonstrate a 13.92 % increase in interfacial adhesion strength of Ni-based coatings due to air plasma modification, reaching 14.16 N. This study underscores the considerable potential of plasma treatment techniques to significantly enhance the interfacial adhesion between substrate and electrodeposited nickel, thus presenting promising applications in novel electrodeposited coatings and related fields.