Journal of the Korean institute of surface engineering (한국표면공학회지)

The Korean Institute of Surface Engineering (한국표면공학회)
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A Study on the Growth and Burning of Anodic Oxide Films on Al6061 Alloy During Anodizing at Constant Voltages

Al6061 합금의 정전압 아노다이징 피막의 형성거동 및 버닝에 대한 연구

  • Received : 2020.01.11
  • Accepted : 2020.02.28
  • Published : 2020.02.29
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Abstract

In this study, growth and burning behavior of 6061 aluminum alloy was studied under constant anodic voltages at various temperatures and magnetic stirring rates in 20% sulfuric acid solution by analysing I-t curves, measuring thickness and hardness of aluminum anodic oxide (AAO) films, observations of surface and cross-sectional images of AAO films. AAO films were grown continuously at lower voltages than 18.5V but burning occurred when a voltage more than 19V was applied in 20% H2SO4 solution at 20±0.5℃ and 200 rpm of magnetic stirring. The burning was always related with an extremely large increase of anodic current density with anodizing time, suggesting that high heat generation during anodizing causes deteriorations of AAO films by chemical reaction with acidic solutions. The burning resulted in decreases of film thickness and hardness, surface color brightened and formation of porous defects in the AAO films. The burning voltage was found to decrease with increasing solution temperature and decreasing magnetic stirring rate. The decreased burning voltages seem to be closely related with increased chemical reactions between AAO films and hydrogen ions.

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References

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