Effect Of Fine Particle Peening Induced Material Transfer On The Initial Deposition Behavior Of Nickel Electroplating On Aluminum Substrate

Plating on aluminum requires a complex zincate pretreatment. Fine Particle Peening (FPP), using particles ≤200 µm, has gained attention as an alternative due to its ability to transfer particle components onto the surface, potentially improving deposition and adhesion. Previous studies showed enhanced plating on aluminum treated with steel particles. This study investigates the effectiveness of FPP as a pretreatment for nickel electroplating by examining initial deposition behavior. A1050-H24 aluminum was treated using FPP with either steel or glass particles, compared to an untreated specimen. Steel particle FPP created a lamellar microstructure with alternating iron and aluminum phases. EBSD revealed that FPP significantly refined the aluminum grain size, about one-hundredth that of the untreated sample. This microstructural refinement resulted from the FPP process. Nickel electroplating was conducted following FPP and nitric acid pickling. Nickel was preferentially deposited in areas with transferred iron in steel-peened specimens. In contrast, glass-peened specimens exposed aluminum-silicon phases, likely from embedded glass particles, and showed less nickel deposition. These results indicate that transferred components, such as iron, promote initial nickel deposition, suggesting FPP with suitable particles can serve as an effective plating pretreatment for aluminum.