Statistical Optimization of Exploring the Effect of Electrolyte Types and Additives on the Hardness of Aluminum 6061 Alloy during Microarc Oxidation process

Abstract

Aluminum 6061 alloy is the most frequently used aluminum alloy in automobile, aircraft, and aerospace industries. However, poor wear and corrosion resistances, considerably affecting their scaled-up applications. Microarc oxidation (MAO) is ecofriendly, straightforward, efficient, and rapid technique for improving the surface characteristics of aluminum alloys and proves to be a highly effective surface treatment technique to enhance the corrosion and wear resistances of aluminum alloys. This article describes progresses realized in recent years for understanding the effects of electrolyte type, electrolyte composition, and additives on the morphology and  properties of MAO coating film, and  on the hardness of MAO coatings .Usually, applying an electrolyte system and introducing some additives in appropriate concentrations can improve the quality of the MAO coatings and their hardness, whereas some additives have negative effects on the hardness which is related to the corrosive behavior of aluminum. The statistical analysis showed that the microhardness values of the MAO coatings which was prepared in Na₂AlO₂ electrolyte was greater than the one which was prepared in Na₂SiO₃ electrolyte with percentage of 62 %. It is also found that the coatings generated by using pulsed-bipolar mode power source in MAO gives superior characteristics, and adding additives to electrolyte is not always enhance hardness and wear resistance.