Optimization of allotropic and hardness of aluminum oxide coating by PEO

Babak Ghorbanian; Mohammad Tajally; Seyed Mohammad Mousavi Khoie; Hossien Tavakoli

paper

Optimization of allotropic and hardness of aluminum oxide coating by PEO

arXiv:2005.07471

Abstract

One of the most important methods of producing materials and oxide coating is plasma electrolytic oxidation (PEO). Coatings made on aluminum in PEO method have two allotropes of $α$ -Al $_{2}$ O $_{3}$ and $γ$ -Al $_{2}$ O $_{3}$ . Coatings containing $α$ -Al $_{2}$ O $_{3}$ have more hardness and wear resistance; therefore, the main goal of the present study is to optimize aluminum oxide allotrope for increasing the ratio of $α$ -Al $_{2}$ O $_{3}$ in coating made with PEO method. Results of the present study shows that the optimum electrolyte compound for making highest phase of $α$ -Al $_{2}$ O $_{3}$ has 2.9 g/lit of KOH, 1.15 g/lit of Na4P2O7, and 0.34 g/lit of NaAlO2 and ratio of highest allotropic pick of $α$ -Al $_{2}$ O $_{3}$ to highest allotropic pick of $γ$ -Al $_{2}$ O $_{3}$ (in XRD test) in the optimum condition is 0.622 and hardness is 1648 Vickers.

e.g.: 9 pages, 3 figures, 1 table