Effects of Gallium Addition on the Microstructure and Electrochemical Properties of Al-Zn-Bi Series Alloy Anode

摘要

The open circuit potential, working potential and current efficiency of Al-5Zn-0.5Bi and Al-5Zn-0.5Bi-0.015Ga alloys in artificial seawater were tested by constant current method. The corrosion characteristics of the anode alloys in 3.5% NaCl solution were studied by polarization curves and electrochemical impedance spectra. The surface corrosion morphology and microstructures of the alloys were observed and investigated by metallographic microscopy, scanning electron microscopy and X-ray energy dispersive analysis. The results show that the open circuit potential shifts towards negative, working potential becomes stable and the current efficiency becomes high through the addition of gallium in the alloy. Gallium can be uniformly dissolved in aluminum alloy and effectively reduce the segregation of Bi. The cations can deposit back to the anode surface forming into the Ga-Al amalgam, which promotes its homogeneous dissolution and improve comprehensive electrochemical performance.