Effect of Anodizing Conditions on Wear Resistance,Surface Hardness and Change of Dimensions on Aircraft Aluminum Alloys

Aluminum alloys are widely used in the aircraft industry due to the high strength-to-density ration. Anodic oxidation, which is an electrochemical process to form stable films on the surface of metals, is one of the most unique and widely used methods to improve surface performance such as corrosion and wear resistance. In this report different aircraft Al alloys e. g. 7075-T6، 2024-T3, 6061-T6 are coated by hard anodizing in different thicknesses (25µm, 50µm, 64µm, 76µm, 100µm) using different current densities (2. 6, 3. 2) and, wear properties, micro-hardness, increase in dimensions of samples in sealed and unsealed conditions are studied. Samples were anodized in sulfuric acid. Test results show uniform coating in all alloys and, decrease of wear of samples in sealed beside non-sealed condition. The sealing process has little effect on reduction of hardness of samples. Hardness of all samples is increased with up to 3 mil increase in thickness of coating and, is decreased thereafter and addition of dimensions is increased by increase in current density.