Abstract

The influence of boric acid, at concentrations of 0.1 and 0.5 M, on anodizing AI 2024-T3 at constant current density in 0.5 M sulphuric acid electrolyte, has been investigated. From the voltage time responses and oxide thicknesses measurements after 30 min anodizing, addition of boric acid has negligible effects on the general anodizing behavior of the alloy. However, in the initial stages of anodizing, the presence of boric acid in the electrolyte strongly reduces the occurrence of secondary electrochemical reactions, consuming electrical charge, consequently increasing the initial efficiency for anodic oxide formation. The effect of boric acid in the initial stages of anodizing the alloy is attributed mainly to the inhibition of oxygen evolution on CuAI2 particles by precipitation of partially or, totally dehydrated boron oxide.