L245钢基体表面Ni-Sn-P化学镀合金镀层耐腐蚀性能研究

Study on Corrosion Resistance of Ni-Sn-P Electroless Plating on L245 Steel Surface

采用极化曲线探讨了L245钢和L245钢基体表面Ni-Sn-P化学镀层的耐腐蚀性能;利用电子扫描显微镜和能谱分析仪观察了L245钢表面Ni-Sn-P化学镀层在高压釜酸性介质情况下腐蚀前后的表面形貌和成分,结合X射线、光电子能谱对腐蚀后Ni-Sn-P化学镀层表面的组成进行了XPS分析。结果表明:Ni-Sn-P化学镀层在3.5%NaCl溶液中的电化学性能很好,明显高于基体L245钢;Ni-Sn-P化学镀层在高压釜酸性介质腐蚀情况下,Ni、Sn元素溶解,P元素富集,腐蚀层区域均匀,没有出现像L245钢那样的腐蚀坑;高压釜腐蚀后的Ni-Sn-P化学镀层表面形成了由NiO2、NiO、NiCl2、Ni(OH)2、NiSO4、SnO2、SnO、Ni3(PO4)2和Sn3(PO4)4等化合物组成的保护膜,对提高Ni-Sn-P化学镀层的耐腐蚀性能起到了重要作用。

The corrosion resistance of Ni-Sn-P electroless plating on L245 steel surface was studied. The anti-corrosion was evaluated with potentiodynamic polarization curve. The changes of microscopic morphology and elemental composition of Ni-Sn-P electroless plating on L245 steel surface before and after corrosion by autoclave test in acid medium were analysed with SEM and EDS, and the corrosion products were examined with X-ray and photoelectron spectroscopy（XPS）. The results show that, the electrochemical properties corrosion of Ni-Sn-P electroless plating on L245 steel surface is much better than the L245 steel in 3.5% NaCl solution. With Ni-Sn-P electroless plating on L245 steel surface in acidic medium, Ni and Sn elements dissolve, P element enriches. The region of corrosion layer is uniform. There is no corrosion pits like L245 steel.After corrosion, a layer of passive film composed of NiO2, NiO, NiCl2, Ni（OH）2, NiSO4, SnO2, SnO, Ni3（PO4）2, Sn3（PO4）4is formed on the surface of Ni-Sn-P electroless plating, which plays an important role in improving Ni-Sn-P electroless plating corrosion resistance.