AZ91D镁合金表面Ni-P/Ni-Sn-P双镀层的制备与性能研究  

Study on the Preparation and Properties of Ni-P / Ni-Sn-P Duplex Coatings on AZ91D Magnesium Alloy

作　　者：刘秋月[1] 张修庆[1] 浦海洲 徐金鹏[1] 

机构地区：[1]华东理工大学机械与动力工程学院,上海200237

出　　处：《表面技术》2015年第2期34-37,133,共5页Surface Technology

摘　　要：目的提高AZ91D镁合金的耐腐蚀性能,扩大其应用范围。方法先在AZ91D镁合金表面化学镀Ni-P镀层,再化学镀Ni-Sn-P镀层,形成Ni-P/Ni-Sn-P双镀层。研究Ni-P/Ni-Sn-P双镀层的表面形貌和耐腐蚀性能,并与Ni-P单镀层进行对比。结果 Ni-P/Ni-Sn-P双镀层表面分布更均匀平整,缺陷较少,孔隙率较低,具有无定形结构。二次Ni-Sn-P镀层的腐蚀电位约为-0.77 V,略低于一次化学镀Ni-P层(约-0.68 V),两镀层间的电位差使得其构成了微腐蚀电偶,Ni-P层作为阴极,Ni-Sn-P层作为阳极,阳极优先被腐蚀。结论 Ni-P/Ni-Sn-P双镀层的Ni-Sn-P外层能为Ni-P内层提供阴极保护,较好地横向分散腐蚀电流,从而增强AZ91D镁合金基底的耐腐蚀性能。Objective To improve the corrosion resistance of AZ91 D magnesium alloy and expand the range of application.Methods Ni-P coating was first prepared on AZ91 D magnesium alloy by electroless plating,then Ni-Sn-P coating was prepared on this basis,forming Ni-P / Ni-Sn-P duplex coatings. The microstructure and corrosion resistance of Ni-P / Ni-Sn-P duplex coatings were investigated and compared with those of Ni-P coating. Results The results showed that the surface of Ni-P / Ni-Sn-P duplex coatings was more uniform,compact,with fewer defects,lower porosity and amorphous structure. The corrosion potential of the secondary Ni-Sn-P coating was about- 0. 77 V,which was lower than that of the first Ni-P coating（- 0. 68 V）. The potential difference between the two coatings formed micro etching point,with Ni-P coating as the cathode,and Ni-Sn-P coating as the anode,and the anode was corroded first. Conclusion The outer layer of Ni-Sn-P coating in the Ni-P / Ni-Sn-P duplex coatings could protect the first Ni-P coating from corroding and diffuse the corrosion current in the horizontal direction,thus greatly enhancing the corrosion resistance of AZ91 D magnesium alloy.

关 键 词：AZ91D镁合金 NI-P镀层 Ni-P/Ni-Sn-P双镀层 耐腐蚀性能 

分 类 号：TQ153.2[化学工程—电化学工业]