Corrosion Resistance of Hot Dipping Al-Zn-Si and Zn-Al-Mg-Si Alloy Coating

A comparative research on the characteristics and corrosion resistance of two kinds of hot dipping alloy coating section for 55%Al-43.5%Zn-1.5%Si and Zn-11%Al-3%Mg-0.2%Si. The distribution and organization of the crosssectional elements were analyzed by glow discharge apparatus and metallurgical microscope. And electrochemical workstation was applied to test Tafel polarization curves and electrochemical impedance spectroscopy. The results showed that 55% zinc Al-43.5%-Si alloy coating surface was mainly Al and Zn, near the inner side main ingredients for Fe, Al, and the corrosion potential of 1050.7 mV; Zn-11%Al-3%Mg-0.2%Si alloy coating surface composition was mainly Zn, Al, Mg, and close to the inside the main components is Fe, Zn, the corrosion potential of -710.7 mV. The corrosion resistance of 55%Al-43.5%Zn-1.5%Si alloy coating was significantly better than the Zn-11%Al-3%Mg-0.2%Si coating.