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Dielectric Breakdown Behavior of Anodic Oxide Films Formed on Pure Aluminum in Sulfuric Acid and Oxalic Acid Electrolytes

  • Hien Van Pham (Nano-Surface Materials Division, Korea Institute of Materials Science) ;
  • Duyoung Kwon (Nano-Surface Materials Division, Korea Institute of Materials Science) ;
  • Juseok Kim (Nano-Surface Materials Division, Korea Institute of Materials Science) ;
  • Sungmo Moon (Nano-Surface Materials Division, Korea Institute of Materials Science)
  • Received : 2022.12.19
  • Accepted : 2023.06.14
  • Published : 2023.06.30

Abstract

This work studies dielectric breakdown behavior of AAO (anodic aluminum oxide) films formed on pure aluminum at a constant current density in 5 ~ 20 vol.% sulfuric acid (SA) and 2 ~ 8 wt.% oxalic acid (OA) solutions. It was observed that dielectric breakdown voltage of AAO film with the same thickness increased with increasing concentration of both SA and OA solutions up to 15 vol.% and 6 wt.%, respectively, above which it decreased slightly. The dielectric breakdown resistance of the OA films appeared to be superior to that of SA films. After dielectric breakdown test, cracks and a hole were observed. The crack length increased with increasing SA film thickness but it did not increase with increasing OA film thickness. To explain the reason why shorter cracks formed on the OA films than the SA films after dielectric breakdown test, the generation of tensile stresses at the oxide/metal interface was discussed in relation to porosity of AAO films obtained from cross-sectional morphologies.

Keywords

Acknowledgement

This work was supported by the UST Young Scientist Research Program 2020 through the University of Science and Technology (No. 2020YS19) and by Fundamental Research Program of the Korean Institute of Materials Science (KIMS, PNK9450).

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