Influence of Ga and Bi on electrochemical performance of Al-Zn-Sn sacrificial anodes

The influence of Ga and Bi on the microstructure and electrochemical performance of Al-7Zn-0.1Sn (mass fraction, %) sacrificial anodes was investigated by means of optical microscopy (OM), scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDAX) and electrochemical measurements. It was found that the coarse dendrites structure transformed into the equiaxed grains as well as a small amount of dendrite grains after adding Ga and Bi into Al-Zn-Sn alloys. A high current efficiency of 97% and even corrosion morphology were obtained for Al-7Zn-0.1Sn-0.015Ga-0.1Bi alloy. The results indicate that the proper amount of Ga and Bi is effective on improving the microstructure and electrochemical performance of Al-Zn-Sn alloy.