Comparison of Aluminium Oxide Pore Structure with Anodizing in Single Acid and Mixed Acid Systems

Abstract

This research studies the aluminium oxide (Al₂O₃) pore structure on the surface of aluminium alloy. Aluminium alloys was anodized under constant anodizing potential 24 V for 25 min. The experiment was divided into 3 parts as follows; the part 1 was the comparison of using electrolyte solution as a single acid and mixed acid at 20°C. In the part 2, the anodizing temperatures of 10, 20, 30 and 40°C were compared by using an electrolyte solution as a mixed acid of citric acid and sulfuric acid at a mass-volume ratio of 0.166 g/ml. In the part 3, the mass-volume ratios of mixed acid to 0.166, 0.332, 0.664, 0.996, 1.328 and 1.660 g/ml at temperature of 40°C were studied. Analysis with Field Emission Scanning Electron Microscope (FE-SEM) and Laser Scanning Microscope (LSM), it is clear that the anodized structure of aluminium oxide has irregular arranged small units and destruction characteristic is rare when the anodizing conducted of single acid as citric acid or mixed acid with mass-volume ratio equal to 0.166 g/ml  at temperature not over 30°C.