Zr-8.8Al合金化学镀前的磷化预处理工艺

Phosphating Preplating Process for Electroless Plating on Zr-8.8Al Alloy

预处理工艺的选择直接影响化学镀Ni-P镀层质量的高低。采用磷化法对Zr-8.8Al合金进行了化学镀前的预处理,研究了Zr-8.8Al合金在不同磷化工艺下获得的磷化膜以及化学镀Ni-P镀层的显微结构、显微硬度、抗蚀性等。结果表明,45℃/2 min预处理获得的磷化膜均匀致密;在此工艺下进行化学镀获得的Ni-P镀层为非晶、胞状结构,厚度达25μm。与裸材相比,Ni-P镀层显微硬度提高了60%,在质量分数为3.5%的Na Cl溶液中自腐蚀电位发生正移,极化腐蚀后镀层胞状较完整,对Zr-8.8Al合金起到了较好的保护作用。

The quality of electroless Ni-P plating is dependent on the process of pretreatment. Phosphating pretreatment was preformed for electroless Ni-P plating on Zr-8.8Al alloy. The effect of phosphating process on the microstructure, microhardness and corrosion resistance in 3.5 wt% Na Cl solution of electroless Ni-P plating was investigated. The results show that the phosphating film obtained at 45 °C for 2 min is uniform and dense. The electroless Ni-P plating has amorphous cellular structure with about 25 μm in thickness. Compared with nonplated alloy, the microhardness of electroless Ni-P plating after phosphating pretreatment is improved by 60%. The corrosion potential of electroless Ni-P plating after phosphating pretreatment in 3.5 wt% Na Cl solution shift positively. The cellular structure of the plating after corrosion is still complete, indicating that the corrosion resistance of electroless Ni-P plating after phosphating pretreatment is excellent.