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在化学镀Ni-P层和AZ91D镁合金之间生成磷酸锰、单宁酸或钒转化膜预处理层,以取代传统的铬酸盐加氢氟酸预处理工艺。电化学测试结果表明:与传统的铬酸盐处理加化学镀相比,镁合金上的无铬转化膜加化学镀镍磷具有低的腐蚀电流密度和更正的腐蚀电位,能够减少基体上化学镀层的腐蚀。因此,镀层具有致密的细晶结构,适当的磷含量、低孔隙度和良好的耐蚀性并且和基体结合良好的涂层可以取代传统的铬酐钝化加化学镀的工艺。
In the electroless Ni-P layer and AZ91D magnesium alloy generated manganese phosphate, tannin or vanadium conversion coating pretreatment layer to replace the traditional chromate hydrofluoric acid pretreatment process. Electrochemical test results show that compared with the conventional chromate treatment and electroless plating, the chromium-free conversion coating on the magnesium alloy and electroless nickel phosphorus have a low corrosion current density and a corrected corrosion potential, which can reduce the electroless plating on the substrate Corrosion. Therefore, the coating has a dense fine-grained structure, appropriate phosphorus content, low porosity and good corrosion resistance and good substrate combination can replace the traditional chromic passivation and electroless plating process.