镁合金上化学Ni-P-硬质氧化物复合镀层

Ni-P-hard oxide composite coatings on Mg alloy substrate

结合溶胶-凝胶法和化学镀方法,于镁合金基材表面成功制备了均匀的复合Ni-P-SiO2/TiO2/Al2O3镀层,采用扫描电镜(SEM)、光学显微镜(OM)、摩擦磨损试验及电化学方法,对比研究了Mg基材、基础Ni-P镀层与3种复合镀层的显微组织结构、耐磨性及耐腐蚀性。结果表明,加入3种溶胶所制备的复合镀层较Mg基材大幅度提高耐磨性和耐腐蚀性;3种复合镀层较Ni-P镀层具有更加均匀、致密的显微形貌,减少了直接加入纳米粉末的团聚,同时耐磨和耐蚀性改善。其中Ni-P-SiO2复合镀层具有较高的显微硬度(HV513)和最低的摩擦系数(0.34),最高的腐蚀电位(-1.18V)及较小的腐蚀电流密度(9.5×10^-3mA·cm^-2)。综合制备最佳工艺,并考虑节能减排因素,Ni-P-SiO2复合镀层可作为性能优良的Mg合金耐磨、耐腐蚀镀层使用,于实际工业生产大有裨益。

The sol-gel method and electroless plating method were combined to successfully prepare three homogeneous composite coatings composed of nickel-phosphorus-hard oxides(Ni-P-SiO2/TiO2/Al2O3)on the surface of the magnesium alloy substrate.Scanning electron microscopy(SEM),optical microscopy(OM),friction and wear tests,and electrochemical methods were used to compare the microstructure,wear resistance and corrosion resistance of Mg substrates,basic Ni-P coatings and three composite coatings.Results show that compared with the Mg substrate,the composite coatings prepared by adding the three sols had their wear resistance and corrosion resistance greatly improved.Compared with the Ni-P coating,the three composite coatings have more uniform and dense micro-morphology,which reduces the agglomeration caused by directly adding nano-powder,while improving the wear resistance and corrosion resistance.The Ni-P-SiO2 composite coating is found to have a superior microhardness of HV513,a minimum friction coefficient of 0.34,and a most positive corrosion potential of-1.18V and a minor corrosion current of 9.5×10^-3m A·cm^-2.Therefore,considering the best preparation technology and energy saving and emission reduction factors,Ni-P-SiO2 composite coating can be used as a wear-resistant and corrosion-resistant coating of Mg alloy for its excellent properties,which is beneficial to practical industrial production.