稀土Ce含量对双脉冲电沉积Ni-Co合金层结构及耐蚀性的影响

Influences of Rare Earth Cerium Content on the Structure and Corrosion Resistance of Ni-Co Alloy Coating Prepared by Dual-Pulse Electrodeposition

目前将稀土用作电沉积Ni-Co合金添加剂时有关其对镀层耐蚀性的影响报道较少。通过X射线衍射、极化曲线和中性盐雾试验研究了稀土Ce对双脉冲电沉积纳米Ni-Co合金层晶粒尺寸及耐蚀性的影响,采用扫描电镜对有无稀土Ce的Ni-Co合金镀层盐雾腐蚀前后的表面形貌进行了观察。结果表明:无论是否添加稀土Ce,Ni-Co合金镀层均为面心立方结构,主要的晶面取向为(111)和(200)面;稀土Ce含量在一定范围时,细化了Ni-Co合金镀层的晶粒,镀层的自腐蚀电位正移,自腐蚀电流减小,耐蚀性增加,且加入量为0.6g/L时晶粒尺寸最小。

The effects of rare earth cerium(Ce) on the grain size and corrosion resistance of the Ni- Co alloy coatings were studied by X-ray diffraction(XRD),polarization curve measurement and neutral salt spray test.Subsequently,the surface morphologies of the Ni-Co alloy coating deposited with or without Ce element before and after salt spray test were observed by scanning electron microscopy.Results showed that irrespective of adding Ce element or not,the crystal structure of Ni-Co alloy coatings was face- centered cubic(fcc) with(111) and(200) crystal orientation.Moreover,with a certain content of Ce,the crystal particle of Ni-Co alloy coating became refined,and the corrosion resistance of coatings was improved with the positive shift of the self-corrosion potential and the decrease of self-corrosion current.When the content of Ce was 0.6 g/L,the Ni-Co alloy coating had the minimum grain size.