Analysis of Morphology and Growth Kinetics of Zn-Mn and Zn-0.2wt.Al-Mn Hot-dip Galvanizing Coatings

摘要

The influence of manganese in Zn-Mn and Zn-0.2wt.%Al-Mn bath on the morphology and growth kinetics of the galvanizing coatings has been studied using scanning electron microscopy equipped with energy dispersive spectroscopy. When galvanized in zinc bath, the coating consists mainly η and ζ phase. When manganese is added in zinc bath, the morphology of ζ phase changes from fragmental to compact. Manganese favors the formation of the δ phase and inhibits the growth of the ζ phase. When galvanized in Zn-0.2wt.%Al bath, the coating consists only δ and ζ phase. With the addition of manganese in Zn-0.2wt.%Al bath, the morphology of δ phase changes from fragmental to compact The thickness of the Fe-Zn intermetallic phase layer in coatings decreases obviously when manganese is added into zinc and Zn-0.2wt.%Al bath, and the thickness increases slowly with the increase of immersion time.