Electrochemical properties research of Al-Zn-Bi series alloy in NaCl solution

Polarization curves and electrochemical impedance spectroscopy(EIS)of alloys Al-5Zn-0.5Bi and Al- 5Zn-0.5Bi-0.06Sn in 3% NaCl solution are tested by CHI660C electrochemical workstation and their electro- chemical properties are examined.The results show that self-corrosion potential Ecorr increase 0.017V and cor- rosion resistance performance is slightly enhanced after adding 0.06% Sn to Al-5Zn-0.5Bi.The electrochemical corrosion process of Al-5Zn-0.5Bi series alloy in 3% NaCl solution can be precisely described by equivalent cir- cuits R_s(R_pC)(QR_D(R_sL)).The corrosion film will thicken and partly desquamate to form pitting with increas- ing immersing time in 3% NaCl solution.In addition,corrosion products,inhabiting the diffusion of Cl~- into interior and decreasing the corrosion pits and self-corrosion speed,more easily form in defect of oxidation film of Al-5Zn-0.5Bi-0.06Sn than that of Al-5Zn-0.5Bi,which will help to improve this alloy current efficiency as sac- rificial anode material.