Anodic Electrochemical Behaviors of 2219 Aluminum Alloy in NaNO₃ and NaCl Electrolytes

Abstract

Because to its exceptional performance, 2219 aluminum alloy is extensively employed in the aerospace sector for large thin-wall structures. However, the machining of such structures commonly results in issues like chatter and deformation, making electrochemical machining (ECM) the preferred method. The primary focus of ECM for anode materials involves understanding their behavior during the electrochemical dissolution process. The anode electrochemical behavior of 2219 aluminum alloy in 10 wt% NaNO3 electrolyte and 10 wt% NaCl electrolyte is reported for the first time. Passivation-related characteristics and interface structures were assessed through linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy curves. The growth and composition of passivated films were determined through open-cricuit potential and X-ray photoelectron spectroscopy analyses. Results indicate that in NaNO3 electrolyte, a thicker and more stable passivation film forms, enhancing corrosion resistance and inhibiting material dissolution. ECM tests reveal pitting in 2219 aluminum alloy under low current density, with the oxide layer breaking at higher densities. Notably, ECM of 2219 aluminum alloy with NaNO3 electrolyte yields superior surface morphology, evident in both microstructure and macro-morphology.