Interfacial Reaction of Ni (P)-Sn Coating on Magnesium
Hot dip tin coating was obtained on AZ91D magnesium alloy surface, and interfacial reactions between Sn coating and electroless Ni-P plating was studied. The results show: after 220±5°C, 2h diffusion, the intermetallic compounds possessed corresponding thickness, and Ni3P layer along the interface acted as a good diffusion barrier between Sn and Ni. When Ni3Sn4 spread to the surface, microcracks were observed on the surface. Corrosion resistance of Ni(P)-Sn coating before and after diffusion was investigated with polarization curves. The results show: Ni(P)-Sn coating significantly enhance the corrosion potential of base material, but after the Ni3Sn4 growth to the surface, it caused electrochemical corrosion and decreased the corrosion resistance.
Long Chen, Yongkang Zhang, Aixing Feng, Zhenying Xu, Boquan Li and Han Shen
X. L. Ge et al., "Interfacial Reaction of Ni (P)-Sn Coating on Magnesium", Key Engineering Materials, Vol. 464, pp. 514-517, 2011