镍/铜/锌多层镀层的制备及其耐蚀性

摘要

采用电沉积法在低碳钢基体上制备了镍/铜/锌多层镀层.采用扫描电镜观察镍/铜/锌多层镀层的微观结构;通过盐水(NaCl质量分数为5％)浸泡试验对制得的镍/铜/锌多层镀层进行耐蚀性评价;利用电化学阻抗谱(EIS)技术测试镍/铜/锌多层镀层在5％ NaCl(质量分数)溶液中的电化学性能.结果表明:底层镍镀层颗粒以四角锥型交错堆积,中间层铜镀层颗粒以圆胞型结构沉积,表层锌镀层的表面平整致密,无明显孔隙;镍/铜/锌多层镀层具有较好的耐蚀性,电化学阻抗达到了5 623 Ω· cm2,耐盐水浸泡时间可达2 880 h时,是相同厚度单一镀层耐盐水浸泡时间的5～8倍.%Ni/Cu/Zn multilayer coating was prepared on low carbon steel substrate by electrodeposition.The microstructure of the Ni/Cu/Zn multilayer coating was observed by scanning electron microscopy (SEM).The corrosion resistance of the Ni/Cu/Zn multilayer coating was evaluated by the brine immersion testing in which NaCl mass fraction was 5％.The electrochemical properties of Ni/Cu/Zn multilayer coating in,5.0％ (mass) NaCl solution were measured by electrochemical impedance spectroscopy (E IS) technique.The results show that:the particles in the under layer of nickel were stacked interlacedly as four pyramid type,the particles in the middle layer of copper were deposited by round cell structure,and the surface layer of zinc was flat and compact without apparent pores.The Ni/Cu/Zn multilayer coating exhibited good corrosion resistance,showing a value of electrochemical impedance of 5 623 Ω · cm2.The immersion time of red rust spot occurring on the coating surface in brine reached 2 880 h which was 5-8 times of that for single layer coating with the same thickness.