Fabrication and characterization of ceramic coating on al7075 alloy by plasma electrolytic oxidation in molten salt

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21 Scopus citations

Abstract

The fabrication of a ceramic coating on the metallic substrate is usually applied to achieve the improved performance of the material. Plasma electrolytic oxidation (PEO) is one of the most promising methods to reach this performance, mostly wear and corrosion resistance. Traditional PEO is carried out in an aqueous electrolyte. However, the current work showed the fabrication and characterization of a ceramic coating using PEO in molten salt which was used to avoid disadvantages in system heating-up and the formation of undesired elements in the coating. Aluminum 7075 alloy was subjected to the surface treatment using PEO in molten nitrate salt. Various current frequencies were applied in the process. Coating investigations revealed its surface porous structure and the presence of two oxide layers, α-Al2 O3 and γ-Al2 O3 . Microhardness measurements and chemical and phase examinations confirmed these results. Potentiodynamic polarization tests and electrochemical impedance spectroscopy revealed the greater corrosion resistance for the coated alloy. Moreover, the corrosion resistance was increased with the current frequency of the PEO process.

Original languageEnglish
Article number993
Pages (from-to)1-12
Number of pages12
JournalCoatings
Volume10
Issue number10
DOIs
StatePublished - Oct 2020

Keywords

  • Al7075 alloy
  • Aluminum oxide
  • Corrosion resistance
  • Microhardness
  • Molten salt
  • Plasma electrolytic oxidation (PEO)

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