Creation of oxide coating on Al 1050 alloy

TL;DR

This study explores a novel plasma electrolytic oxidation method using nitrate molten salt for Al 1050 alloy, producing high-quality oxide coatings without typical aqueous electrolyte issues.

Contribution

It introduces an alternative PEO process in nitrate molten salt, enabling large surface treatment and producing contaminant-free, damage-free oxide coatings on aluminum alloy.

Findings

Coating contains α-Al2O3 and γ-Al2O3 phases.

Coating free of electrolyte contaminants.

No damages observed in the coating.

Abstract

Plasma electrolytic oxidation (PEO) is a surface processing for oxide coatings formation with advanced properties. Mostly, PEO is performed in an aqueous solution electrolyte which limits the dimension of treated parts due to the system heating up. Therefore, treatment of large surfaces cannot be applied in aqueous electrolyte. In current work an alternative approach of PEO treatment applied in aluminum 1050 alloy in nitrate molten salt was investigated. The structure, phase and chemical compositions, and micro-hardness were examined using XRD, SEM, EDS and micro-hardness tests. The obtained results showed that formed coating contains from two phases of {\alpha}- Al2O3 and {\gamma}- Al2O3. It was found that formed coating is free of any contaminants originated from the electrolyte and has no damages, which are usually present in coatings formed in PEO treatment in aqueous solution electrolyte.