Influence of Conventional Shot Peening on Adhesion, Microstructure, and Corrosion Resistance of Electrodeposited Nickel Coatings on Copper

Abstract

Copper is highly vulnerable to degradation in corrosive environments, necessitating effective surface protection strategies. In this study, nickel coatings were electrodeposited onto copper substrates to improve their properties. However, the as-deposited coatings exhibited inadequate adhesion with surface defects, indicating the need for an additional post-treatment. To overcome this limitation, a surface mechanical treatment through conventional shot peening (CSP) was employed to refine the coating characteristics based on different parameters and further enhance its functional performance. Peened and unpeened Ni coatings were examined through surface morphology and phase analysis to identify treatment-induced microstructural changes. Mechanical and Electrochemical properties were further evaluated to determine the performance improvements from peening. The comparative results manifest that coating adhesion was significantly improved through the formation of a plastically deformed, densified coating layer induced by peening. Correspondingly, the mechanical response exhibited a substantial increase in microhardness by 98.70%. Furthermore, the initially tensile residual (+49 MPa) stress was effectively transformed into a compressive stress (-284 MPa). Due to the increase in roughness, the wettability of nickel peened samples has been improved on the basis of the contact angle. Scratch testing revealed reduced penetration depth in the peened coating, confirming enhanced overall performance resulting from the strengthening effect. The enhancement in corrosion resistance of Ni coatings before and after shot peening was examined through corrosion testing and surface morphology analysis. Overall, the proposed postprocessing approach demonstrates a promising route to enhance the corrosion performance of electrodeposited Ni coatings, offering potential benefits for engineering applications.