Effect of Ni Content on Microstructure and Corrosion Resistance of Hot-dip Zn-Al-Ni Alloy Coating

In order to improve the corrosion resistance of hot-dip galvanizing coating,the hot-dip galvanizing alloy of Zn-Al-Ni were gained on the surface of Q235 steel by adding a small amount of Ni in the Zn-0.01%Al bath.The microstructures of coatings were observed by the optical microscopy,and the corrosion resistance of coatings was characterized by full immersion corrosion test.The results show that the corrosion rate decreases firstly and then increases along with the increase of Ni content in the alloy bath.The corrosion resistance is the best for the coating when the Ni content is 0.05%.The corrosion resistance can be enhanced by reducing the thickness of ζ phase and increasing the thickness of δ phase.