Hard Anodize of 6061-T0 Aluminium Alloy in Sulfuric Acid Bath at Near Zero Temperature and Its Mechanical Properties

Abstract

Hard anodization was a method that can enhance aluminium alloy surface characteristics by growing an aluminum anodic oxide (AAO) film on it surface. This method was very applicable to obtain a thick and hard coating with a small amount of treatment time. This process was carried out at a high current density and low electrolyte temperature. Galvanostatic-potentiostatic mode at high current densities (j = 4.2 A/dm2) and high target voltages (Vt =30 -60 V) was used in this study. Two sulfuric acid electrolyte was compared, the first solution was sulfuric acid 11% vol., the second one was sulfuric acid 11% vol. plus oxalic acid 1% wt, both of them was conditioned at >5°C. The maximum AAO film thickness and hardness obtained was 110.01 µm and 400 HV. The increasment of target voltage was directly proportional to the increase in thickness and hardness of the AAO film.