预处理对AZ91D镁合金化学镀镍的影响

Effect of Pretreatment on Electroless Nickel Plating on AZ91D Magnesium Alloy

以磷酸盐-氟盐-高锰酸盐配制镁合金的活化溶液,实现了镁合金表面直接沉积镍-磷合金镀层。采用扫描电子显微镜、能谱仪和X-射线衍射仪研究了镁合金活化后的形貌和成分。结果表明,活化转化膜层致密,主要成分为MgF_2-Mg_3(PO_4)_2复合结构。极化曲线和结合力测试表明,转化膜可有效地防止镀液对镁基体的腐蚀,所得镍-磷合金镀层致密,具有良好耐蚀性能,且镀层和镁基体间的结合力良好。

To achieve the nickel phosphorus（ Ni-P） coating of magnesium alloy in electroless nickel plating bath,phosphate-villiaumite-permanganate composite system was employed as activation solution for magnesium alloy. Scanning electron microscopy（ SEM）,energy dispersive spectroscopy（ EDS） and X-ray diffraction（ XRD） were carried out to study the morphology and composition of the magnesium alloy via activation. The results shown that the surface of magnesium alloy was compact and the main component was MgF2-Mg3（ PO4）2 composite film. The polarization curves indicated that chemical conversion coating could effectively prevent corrosion of the magnesium substrate in bath,and the dense Ni-P coating had a good corrosion resistance. Thermal shock tests shown good adhesion between Ni-P coating and magnesium alloy substrate.