Cr2O3 Sealing of Anodized Aluminium Alloy by Heat Treatment

✍ Scribed by Junghoon Lee; Yonghwan Kim; Heuiun Jang; Uoochang Jung; Wonsub Chung

• Book ID: 104090001
• Publisher: Elsevier
• Year: 2011
• Tongue: English
• Weight: 786 KB
• Volume: 10
• Category: Article
• ISSN: 1877-7058
• DOI: 10.1016/j.proeng.2011.04.466

✦ Synopsis

Anodizing is an attractive surface treatment process for aluminium alloys to improve hardness, corrosion resistance and wear resistance. Anodized film is composed of an inner thin barrier layer and an outer thick porous layer. By sealing process as a post treatment of anodizing, a porous layer achieves only an improved mechanical and chemical performance also decorative colour. However, dramatically increased hardness could not be achieved by traditional sealing processes. In this study, the sealing of anodized aluminium alloy was carried out by repeating dipping in hexavalent chromium oxide solution and heat treatment. Using XRD and SEM, the variation of anodized layer before and after the sealing was analyzed. Electrochemical corrosion test was also carried out. The hardness and corrosion resistance were compared with traditional sealing methods, such as boiling water and nickel fluoride. By heat treatment after dipping in hexavalent chromium oxide solution, Cr 2 O 3 was formed and it fills pores in the porous layer of anodized film. Thus, the hardness of anodized film was increased and moreover the corrosion resistance was improved.