한국표면공학회지 (Journal of the Korean institute of surface engineering)

  • 제49권3호
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  • Pages.280-285
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  • 2016
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  • 1225-8024(pISSN)
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  • 2288-8403(eISSN)
한국표면공학회 (The Korean Institute of Surface Engineering)
권호 표지
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해양환경용 알루미늄 합금의 플라즈마 전해 산화 시 표면 특성에 관한 불화칼륨(KF)의 영향

Influences of Potassium Fluoride (KF) Addition on the Surface Characteristics in Plasma Electrolytic Oxidation of Marine Grade Al Alloy

  • 이정형 (한국화학융합시험연구원) ;
  • 김성종 (목포해양대학교 기관시스템공학부)
  • 투고 : 2016.06.17
  • 심사 : 2016.06.28
  • 발행 : 2016.06.30
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초록

In this study, we investigated the influences of potassium fluoride(KF) addition on the surface characteristics of plasma electrolytic oxidation(PEO) coating produced on Al alloy. The PEO of marine grade Al alloy(5083 grade) was conducted in KOH 1g/L solution adding different concentrations of KF(0, 1 and 2 g/L) under a galvanostatic regime. With KF addition, unusual behavior was observed on the voltage-time characteristic curves, which can be characterized by the following process: (i) initial rapid increase in voltage (ii) a short plateau after 1st breakdown (iii) gradual increase in voltage (iv) intermittent fluctuation of voltage after 2nd breakdown. The SEM observation revealed irregular surface morphology with KF addition, as compared with one formed without KF addition, which had a reticulate structure. The XRD analysis detected the formation of aluminium hydroxide fluoride hydrate($H_{4.76}Al_2F_{3.24}O_{3.76}$) on surface grown by PEO process with KF. Particularly, at very early stage of the process (~ 120 s), thin film was formed having nanoporous structure, and F element was confirmed on surface by EDS analysis. The thickness and surface roughness of the coating increased with increasing KF concentration. As a result, KF addition was found to be less beneficial influences on PEO of marine grade Al alloy, and therefore needs further research to improve its capability.

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참고문헌

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