Effect of Mn on Microstructure and Growth Kinetics of Hot-dip Galvanized Zn-0.2%Al Alloy Coating
Zn-0.2%Al-Mn alloy coating was galvanized by hot-dip method on the pure iron through adding a amount of Mn to Zn-0.2%Al bath.The influences of Mn additions in the galvanizing bath on the microstructure and growth kinetics of the galvanized coating were studied using optical microscopy and scanning electron microscopy with energy dispersive.The results show that δ phase changes from fragmental to compact and the Mn content in the individual phase increases with the increase of Mn content in the bath.Mn accumulates mainly in the fragmental phase.The thickness of the coating decreases with the increase of the Mn content in the bath.The growth of the coating in Zn-0.2%Al bath is controlled by interfacial reaction,while the growth in Zn-0.2%Al-Mn bath is controlled by diffusion.The diffusion of Zn is restrained by the addition of Mn in zinc bath.