Study on the Influence of Anodization Parameters on Microhardness, Thickness, and Corrosion Resistance of Aluminium Alloy 6063-T6

Abstract

This study investigates the influence of anodization parameters on the surface microhardness and corrosion resistance of aluminium alloy 6063-T6. The alloy was anodized in 1 M H₂SO₄ with or without 10 wt.% oxalic acid, using current densities of 3 and 5 A/dm², electrolyte temperatures of 10 °C and 20 °C, and anodization durations of 30 and 60 min. Surface microhardness was measured using the Knoop method, and corrosion resistance was evaluated via potentiodynamic polarization in 3.5 wt.% NaCl solution. Lower current density (3 A/dm² and reduced electrolyte temperature (10 °C) enhanced corrosion resistance. Microhardness was primarily governed by oxide compactness rather than thickness, with some thin but dense layers exhibiting high hardness values. The optimal combination of high hardness, and superior passivation was achieved without oxalic acid at low current density and temperature. These findings provide practical guidelines for tailoring anodization processes to improve both mechanical durability and corrosion performance of aluminium alloys.