Ni-α-Al_2O_3纳米复合电镀工艺的优选及镀层的硬度和耐蚀性

Optimization of Process for Nickel/Nano-Alumina Electroplating as well as Determination of Hardness and Corrosion Resistance of Resultant Composite Coating

为了提高Ni-Al2O3纳米复合电镀层的硬度和耐蚀性,以正交试验对镀液温度、电流密度、α-Al2O3纳米粒子质量浓度等因素进行了优选,采用扫描电镜、能谱仪、硬度仪及电化学工作站分别研究了镀层的微观形貌、能谱、硬度和耐蚀性。获得了最优工艺条件:镀液温度65℃,阴极电流密度2 A/dm2,Al2O3加入量为10g/L;在此工艺条件下所得Ni-α-Al2O3纳米复合镀层晶粒细小、表面平整、光滑,显微组织致密、均匀,镀层的硬度及耐蚀性比纯镍镀层均有显著提高。

The process for composite electroplating of Ni/nano-Al2O3 was optimized by orthogonal test in relation to bath temperature,current density and concentration(mass fraction) of nanoscale α-Al2O3 so as to increase the hardness and improve the corrosion resistance of the composite coating.The microstructure and elemental composition of the Ni/nano-Al2O3 composite coating were analyzed with a scanning electron microscope and an energy dispersive spectrometer.The hardness and corrosion resistance of the composite coating were evaluated with a hardness meter and an electrochemical workstation,respectively.As the results,the optimized electroplating parameters are suggested as bath temperature of 65 ℃,cathodic current density of 2 A/dm2,and Al2O3 concentration of 10 g/L.Ni/nano-Al2O3composite coating obtained under the optimized electroplating condition is smooth and consists of fine grains with compact and uniform microstructure,and it possesses much higher hardness and much better corrosion resistance than that of electroplated Ni coating.