“…The most popular surface preparations are chemical conversion, micro‐arc oxidation, electrochemical deposition, and sol–gel process, which were developed to improve resistance to corrosion. [ 6–12 ] The most widely used surface protection methods in the aircraft industry are three electrochemical processes: phosphoric acid (PAA), [ 6–8,12–16 ] chromic acid (CAA), [ 8,9,12–14,17–20 ] and sulfuric acid (SAA) [ 8,13,14,17,18 ] anodizing, as well as sol–gel conversion. [ 10–12,21,22 ]…”