镁合金Ni-B化学镀层具有高耐蚀性、高硬度、高耐磨性等特点,具有广泛的应用价值,过去对其研究不够.采用化学镀在AZ31变形镁合金表面制备了Ni-B镀层,研究了酸洗、活化、浸锌等基材预处理工艺对Ni-B化学镀层形貌及性能的影响.结果表明:CrO_3+KF酸洗对基材的腐蚀较轻,而采用CrO_3+HNO_3酸洗时基材腐蚀严重;HF和NH_4NF_2+H_3PO_42种活化作用的机理在于形成MgF_2的中间转换层,保护基材不被镀液腐蚀,HF活化后在基材表面形成了较大面积的MgF_2,活化能力更强,对基材的保护能力更好;浸锌工艺对镀层的性能有较大影响,二次浸锌后锌颗粒和锌层厚度都小于一次浸锌,Ni-B镀层更平整致密,硬度和结合力优于一次浸锌,显微硬度为458 HK,明显高于镁合金基材的硬度(77 HK),同时镀层的耐蚀性也有较大的提高.
Ni-B coating was prepared on the surface of AZ31 deformed Mg alloy by using electroless plating. The effects of pretreatment processing,including pickling, activating and Zn dipping, on the microstructure and corrosion resistance of the Ni- B coating were investigated. Results show that pickling by CrO_3 + KF leads to slight corrosion of Mg alloy sabstrate, while pickling by CrO_3 + HNO_3 causes severe corrosion of the substrate. An intermediate layer of MgF_2 was formed on the surface of the Mg alloy after being activated in aqueous solutions of HF and NH_4 NF_2 + H_3 PO_4, which contributed to the prevention of the Mg alloy substrate from corrosion by the plating solution. And MgF_2 layer of a larger area was formed after being activated in aqueous HF, leading to better activation capability and protection efficiency for the substrate. At the same time, Zn dipping process had a great effect on the corrosion resistance of electroless Ni-B coating, and twice Zn dipping was superior to single Zn dipping. Namely, smaller Zn grains and thinner Zn layer were generated after twice Zn dipping as compared with single Zn dipping. The corresponding clectroless Ni- B coating was more compact and smooth and had a higher hardness and bonding strength as well as much better corrosion resistance.
参考文献
| [1] | 张津;章宗和.镁合金及应用[M].北京:化学工业出版社,2004:211-256. |
| [2] | 刘正;张奎;曾小勤.镁基轻质合金理论基础及其应用[M].北京:机械工业出版社,2002 |
| [3] | 郭艳婷,李建三.镁合金化学镀镍工艺的研究[J].电镀与环保,2006(06):23-25. |
| [4] | K. H. Lee;D. Chang;S. C. Kwon .Properties of electrodeposited nanocrystalline Ni-B alloy films[J].Electrochimica Acta,2005(23):4538-4543. |
| [5] | 闫洪.化学镀Ni-B合金的性能和应用[J].金属功能材料,1997(01):7. |
| [6] | 胡文彬,向阳辉,刘新宽,刘磊,丁文江.镁合金化学镀镍预处理过程表面状况的研究[J].中国腐蚀与防护学报,2001(06):340-344. |
| [7] | 吴丹,杨湘杰.镁合金表面化学转化处理进展[J].材料保护,2007(12):53-56. |
| [8] | 国栋,樊占国,杨中东,赵林,高鹏.镁合金化学镀中预处理氟化镁膜的特征与作用[J].中国有色金属学报,2007(05):789-794. |
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