Three organic corrosion inhibitors on LY12CZ aluminum alloy in acid solution

The inhibiting effect of three organic compounds on the corrosion of LY12CZ aluminum alloy in 0.5M H₂SO₄ solution was investigated. The organic compounds are 2-mercaptobenzoxazole (MBIH), benzotriazole (BTA) and 8-hydroxy-quinoline(8Q). The inhibiting effect to the corrosion dynamics of LY12CZ aluminum alloy in 0.5M H₂SO₄ solution was evaluated by using mass loss method and the corrosion morphology was observed by using optical microscopy (OM), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to study the inhibiting mechanism. The results show that MBIH, BTA and 8Q all provide anti-corrosion protection for LY12CZ aluminum alloy by forming a thin organic layer of insoluble complexes on the surface of the alloy. Their inhibitive properties are given by the following order: MBIH>BTA>8Q. MBIH and BTA provide anti-corrosion protection by absorbing selectively on the corrosion active intermetallic zones and suppressing the cathode processes of corrosion reaction. The whole surface of the alloy was absorbed by 8Q to form chelate 8Q complexes, but the absorbed layer was destroyed as the anode dissolution.