Military Type III Anodizing: The optimal limit within hardening process of aluminium alloy at near zero temperature
Ndaru Adyono, W D Lestari, Luluk Endahwati

University Pembangunan Nasional Veteran Jawa Timur

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. This process was carried out at galvanostatic potentiostatic mode at high current densities (j = 4.2 A/dm2), high target voltages (Vt = 30 to 60 V) and low electrolyte temperature. Two sulfuric acid electrolyte was compared, the first solution was sulfuric acid 11 percent vol., the second one was sulfuric acid 11 percent vol. plus oxalic acid 1 percent wt, both of them was conditioned at below 5 degree celcius. The maximum AAO film thickness and hardness obtained was 110.01 micrometer and 400 HV. The increasment of target voltage was directly proportional to the increase in thickness and hardness of the AAO film. The results of this study could be synergized with the manufacturing process of aluminum alloy-based (Al6061) components at the product finishing stage. The logarithmic regression in the function of target voltage could be used to estimate film thickness and hardness of the films.

Keywords: Aluminium Alloy 6061, Aluminium Anodic Oxide, Hard Anodizing

Topic: Engineering