Characterization Studies of Aluminum Alloy Substrate Surfaces Treated By Oxyanion Esters of Α-Hydroxy Acids and Their Salts

Abstract

In this investigation, first, substrate coupons of commonly used alloys of Aluminum, which are 2024, 6061 and 7075 alloys, were immersed in solutions of inhibitors such as gluconate esters having the formula of (M)x(hydroxyacid)y(M‘aOb)z combining constituents that are already known for high inhibition efficiencies such as hydroxyacids and metal oxyanions. Among other inhibitor solutions used were benzilate esters, gluconate salts, zinc carboxylates, etc. Secondly, after immersions of the mild steel coupons in inhibitors solutions of varying concentrations for different periods of time, they were characterized by means of various surface techniques such as FT-IR, X-Ray, SEM, XPS and digital imaging. As a result of use of these characterization techniques, it is decided whether protective layers of inhibitor compounds are formed on the substrate surfaces due to immersions in the solutions of the inhibitor compounds similar to those of conversion coatings. The results have proven individual consequences for each inhibitor tried and are described in detail herein the paper, which assisted in the assessment of aqueous corrosion inhibition mechanisms of mild steel by oxyanion esters of α-hydroxy acids and their salts.