【摘要】 AZ91D镁合金首先在无铬的磷酸盐溶液中磷化,然后在硫酸盐镀液中镀镍磷合金。用SEM和XRD对磷化膜的化学组成及微观结构进行了表征,探讨了磷化膜及镍磷合金镀层的形成机理。结果表明:磷化膜主要由Zn3(PO4)2.4H2O和单质锌组成,金属锌粒子作为进一步镀镍磷合金的形核催化剂;磷化液中的间硝基苯磺酸钠使磷化膜的一部分微阳极区变为微阴极区,增加了磷化膜的成膜速度并细化了磷化膜结晶;在含4.0 g/L间硝基苯磺酸钠的磷化液中得到的磷化膜上沉积的镍磷合金镀层致密均匀,有较高的耐蚀性,镀层的附着强度符合ISO 2819的要求。更多还原

【Abstract】 AZ91D Magnesium alloy samples were pretreated in zinc phosphating bath,and then were plated Ni-P deposits from the bath containing nickel sulphate.The microstructure of the phosphate coatings were observed using scanning electron mioroscopy（SEM） and the phase composition were analyzed by Xray diffractometer（XRD）.The formation mechanisms of the phosphate coating and the Ni-P deposit were investigated.Result shows that chief compositions of the phosphate coating were Zn₃（PO₄）₂·4H₂O and Zn.Metal zinc crystals become the catalytic particles of the nickel deposition.The sodium metanitrobenzene sulphonate in the phosphating bath increases the micro cathode areas of the phosphate coating and accelerates the formation of the phosphate coating.It was proved that electroless Ni-P deposits onto the phosphate coating obtained from the zinc phosphating bath containing（4.0 g/L sodium）metanitrobenzene sulphonate are denser and has better anticorrosion performance.The adhesion of the electroless Ni-P deposits satisfies the requirement of ISO 2819.更多还原