Submicron free-chromate chemical conversion coatings on AMg-3 aluminum alloy

Abstract

Coatings obtained in solutions of permanganates are known alternatives to thin chromate conversion coatings on aluminum alloys. However, permanganate ion is an insufficiently effective corrosion inhibitor for aluminum in the acidic medium, and, therefore, modified additives are introduced into converting solutions based on it. The present research is devoted to studying the corrosive characteristics of coatings produced by chemical oxidation in the IFKhANAL-2 permanganate composition and its modifications on AMg-3 aluminum alloy. It is shown that iron and nickel salts are most effective as modified additives and subsequent filling of produced coatings in corrosion inhibitor solutions increases their protective properties up to the level of standard chromate coatings. The researched coatings provide protection for 1.5 years under conditions of a humid tropical climate.