Studies on anodizing of aluminium in alkaline electrolyte using alternating current

Abstract

The work reported in this paper concerns a study of the anodizing of aluminium in alkaline electrolyte based on borax (sodium tetraborate) using alternating current. Coating thicknesses of 11 μm were produced from 50 g l⁻¹ borax solution the pH of which is adjusted with sodium hydroxide to a value of 10.5 at 65 °C, using a current density of 1.5 A dm⁻². The effect of bath composition, temperature, current density, anodizing time and pH on the rate of build up of oxide coating and their relation to anodizing voltage and coating ratio were studied.