Corrosion Protection of an Aluminum Alloy with Nontoxic Compound Inhibitors in Chloride Media

In this study, the properties of some compound inhibitors were measured on aluminum alloy (AA)7075-T76 (UNS A97075) in chloride media. The compound inhibitors were composed mainly of phosphate $(PO43−),$ adding a certain proportion of other nontoxic inorganic and organic inhibitors so as to select alternatives to the environmentally hazardous chromate $(CrO42−).$ To make comparisons, chromate and chromate/phosphate were also examined. Three test methods were used: weight loss during immersion, electrochemical polarization, and electrochemical noise analysis. The results showed that the compound composed of phosphate, molybdate, citrate, and benzimidazole (C₇H₆N₂)/benzothiazole (C₇H₅NS) derivatives exhibited an excellent inhibiting power, which was on the same level with that of chromate and chromate/phosphate.