Chemical deoxidation with Cr-free solution for less-polluting pretreatment of aviation aluminium alloy

Deoxidation via chemical etch is an important step in the pretreatment of aluminium alloy chemical oxidation. Typically, the chemical deoxidation of aluminium alloy is carried out in triacid solution that contains chromic anhydride. While the use of Cr (VI) in triacid solution can cause severe chemical contamination. In this paper, we have developed a Cr-free solution for deoxidation, iron sulphate and etch inhibitors are selected to replace Cr (VI). The formula of deoxidation solution was optimised through the combination of single-factor method and Box-Behnken method. The results show that the Cr-free deoxidation solution we proposed shows a deoxidation effect comparable to that of a triacid solution.