Cerium-based conversion coatings to improve the corrosion resistance of aluminium alloy 6061-T6

摘要

Cerium-based conversion coatings were deposited on aluminium alloy 6061-T6 by immersion in two cerium salt sources (chloride- and nitrate-based) assisted with hydrogen peroxide (H_2O_2). The morphology and composition of the coatings were analysed using scanning electron microscopy and energy dispersive X-ray spectroscopy. Electrochemical measurements to assess corrosion behaviour were performed using free corrosion potential, polarisation and electrochemical impedance spectroscopy with a 3% NaCl solution. The influence of H_2O_2 on the generation of the coating was studied by cyclic voltammetry tests. The protective properties of the coating generated are heavily dependent upon the chelating effect, chaotropic anion, the pH and H_2O_2 content.