Ni-SiC纳米复合镀层腐蚀行为的研究

CORROSION BEHAVIOR OF THE Ni-SiC NANOCOMPOSITE COATINGS

通过电化学阻抗谱测试技术初步确定制备具有较好耐腐蚀性能镀层的工艺参数。利用扫描电子显微镜观察镀层的表面形貌;借助浸泡实验、电化学阻抗谱、极化曲线等方法对比分析了Ni-SiC纳米复合镀层和纯Ni镀层在0.5 mol/L NaCl溶液和1 mol/L HNO_3溶液中的耐腐蚀性能。结果表明,SiC纳米颗粒的加入提高了镀层的耐腐蚀性能,且镀层耐腐蚀性能随镀层中SiC纳米颗粒含量的增加而提高。

Ni-SiC nanocomposite coatings were prepared by means of the conventional electrocodeposition method.The technological parameters that make the nanocomposite coatings have a better corrosion resistance in 0.5 mol/L NaCl solution were preliminarily determined by using electrochemical impedance spectroscopy test（EIS）.By comparing the charge transfer resistance of the coatings,it is shown that coatings prepared with current density range of 15 mA/cm^2～20 mA/cm^2 and SiC content of 6 g/L have better corrosion resistance.The structure of coatings were investigated by scanning electron microscopy（SEM）.The corrosion resistance of Ni-SiC nanocomposite coatings and pure nickel coatings in 0.5 mol/L NaCl solution and 1 mol/L HNO_3 solution was analyzed by immersion tests,electrochemical impedance spectroscopy and polarization curves.As immersion time prolonged in 0.5 mol/L NaCl solution,the charge transfer resistance of Ni-SiC nanocomposite coatings and pure nickel coatings reduced rapidly at initial stage and then became stable at later stage.Moreover,the charge transfer resistance of Ni-SiC nanocomposite coatings were higher than those of pure nickel coatings at the most of the immersion time.In addition,the charge transfer resistance of coatings containing SiC particles were 2 to 5 times higher than those of coatings without SiC particles when they were immersed in 1 mol/L HNO_3 solution for 0.5 h.So the SiC nano-particles were helpful to improve the corrosion resistance of the coatings, which increased with increasing SiC content in the coatings.The effect of SiC nano-particles on the corrosion resistance was discussed in details.