Cu/Ag活化对微弧氧化涂层表面化学镀层生长及耐蚀性能的影响

Effect of Cu-/Ag-activation on Growth and Corrosion Resistance of Electroless Plated Ni-film on Plasma Electrolytic Oxidation Coating

微弧氧化(PEO)涂层属于陶瓷性涂层,表面不具有催化活性,需使用金属Pd活化后,再进行化学镀镍。为替代昂贵的Pd活化工艺,分别开发了Cu活化和Ag活化方法。利用场发射扫描电镜对浸镀后Cu/Ag活化复合涂层的镀层表面和截面形貌观察可见,Ag活化后PEO涂层表面镀层更加均匀致密,且厚度更大。经电化学测试表明,Ag活化复合涂层与传统Pd活化复合涂层的耐蚀性能相近,且明显优于Cu活化复合涂层。因此,Ag活化方法在保证复合涂层的耐蚀性能的同时,降低了活化成本。

The plasma electrolytic oxidation(PEO) coating is a ceramic-like coating without catalytic activity of its surface, thus which should be activated with noble metal Pd before an electroless nickel(EN) plating process can be conducted. To replace the expensive Pd-activation process, Cu-activation and Ag-activation methods were developed. A field emission-scanning electron microscopy was employed to characterize the surface morphology and cross-section morphology of EN films on the Cu-and Ag-activated PEO coatings. In comparison with the Cu-activated PEO coating, a thicker, compact and more uniform EN layer film was formed on the Ag-activated PEO coating. Moreover, the results of electrochemical tests shown that the EN film plated on Ag-activated coating presents more or less the same corrosion resistance as the EN film plated on Pd-activated PEO coating, and better than the EN film plated on Cu-activated PEO coating. Hence, the Ag-activation method significantly reduce the cost, and best of all, it guaranteed the corrosion resistance of the composite coating.