Impurity and temperature enhanced growth behaviour of anodic aluminium oxide from AA5052 Al-Mg alloy using hybrid pulse anodization at room temperature. (15th August 2017)

• Record Type: Journal Article
• Authors: Chung, C.K.; Tsai, C.H.; Hsu, C.R.; Kuo, E.H.; Chen, Y.; Chung, I.C.
• Is Part Of: Corrosion science. Volume 125(2017)
• Page Start: 40
• Page End: 47
• Publication Date: 2017-08-15
• Subjects: A. Aluminium -- B. SEM -- C. Anodic films -- C. Oxidation -- 5052 Al alloy; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2017.05.027
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Anodic aluminium oxide (AAO) template is widely used for synthesizing various 1D nanomaterials. AA5052 Al-Mg alloy (96.6%Al-2.6%Mg) is investigated by hybrid pulse anodization (HPA) at 25 °C. HPA avoids failure of AAO from conventional direct-current anodizing (DCA) at 25 °C. Growth rate of AAO by HPA at 25 °C can enhance over three-fold to 9.7 μm/h compared to 2–3 μm/h by DCA at 0–5 °C. High-activity Mg impurities play a crucial role due to high Mg(OH)2 -formation heat released in hydrolysis. Abstract: Conventional anodic aluminium oxide (AAO) was formed using direct-current anodization from high-purity (99.99%–99.999%) Al foils at low 0–5 °C with a growth rate about 2–3 μm/h. Here, we investigate the greatly enhanced growth behaviour of AAO from AA5052 Al-Mg alloy (96.6%Al-2.6%Mg) at high 25 °C using hybrid-pulse anodization. The Mg-impurity and high-temperature enhanced growth rate of AAO at 25 °C is over three-fold to 9.7 μm/h; it also reduces the average pore size to 32.2 nm from 42.8 nm due to high-activity Mg hydrolysis releasing high Mg(OH)2 -formation heat and H2 gas. The unique property of AAO from AA5052 is discussed.