Investigating the Porous Coating Produced on 6061 Aluminum Alloy in Sulfuric Acid Electrolyte at Different Temperatures

Abstract

In this research, the effect of sulfuric acid electrolyte temperature on the surface properties of anodizing coating of 6061 aluminum alloy is investigated. For this purpose, anodizing was done in sulfuric acid environment and 4 different temperatures (-5°C, 5°C, 15°C and 25°C) on 6061 aluminum alloy. Characterization the structure and chemical composition of the coatings by the use of low-angle X-ray diffraction (GIXRD) and Energy-dispersive X-ray spectroscopy (EDS) results showed that the coatings have a non-crystalline structure with aluminum hydroxide as a result of atmospheric hydration of the anodized samples. The results of roughness measurement and Scanning electron microscope (SEM) images indicated that the porosity increased due to the higher corrosive power of sulfuric acid at higher temperatures. Examining the changes of anodizing flow over time determined that higher temperatures of the anodizing solution causes an increase in the anodizing flow and the dissolution rate of the coating. For this reason, the thickness and hardness of the samples, which have a direct relationship with the rate of dissolution and flow, decreased significantly with increasing temperature