为了克服传统线材高速电镀锌工艺存在的镀层耐蚀性能差问题，研究了硫酸盐电镀纳米晶锌镀层的工艺。采用场发射扫描电子显微镜、透射电镜和X－射线衍射技术对镀锌层的表面形貌及晶粒尺寸进行了表征，利用极化曲线和线材缠绕试验对纳米晶锌镀层的耐蚀性能和延展性能进行了研究。结果表明：在基础硫酸盐镀液体系中，仅通过改变脉冲电镀参数并不能得到纳米晶锌镀层；而在含有唯一添加剂（晶粒细化剂1 g／L）的基础硫酸盐镀液体系中，通过对双脉冲电镀参数的优化，得到了平均晶粒尺寸为31 nm，结晶细密、平整、光亮的纳米晶锌镀层；该纳米晶锌镀层在低碳钢板材和线材表面重现性良好；纳米晶锌镀层的耐蚀性能优于传统粗晶锌镀层，且具有良好的延展性。
A novel nanocrystalline zinc electroplating technology in a sulfate bath was investigated so as to overcome the poor corrosion resistance of zinc coatings that exist in the tradtional high speed zinc plating technology for wire rod. The surface morphology and grain size of the coating were studied by field emission scanning electron microscope, transmission electron microscopy and X?ray diffraction. The corrosion resistance and ductility of nanocrystalline zinc coating were also evaluated by potentiodynamic polarization curve and wire winding tests, respectively. The nanocrystalline zinc coating can not been obtained if we just change the pulse current conditions in basic sulfate bath ( zinc sulfate 100 g/L, boric acid 20 g/L when pH value of the solution is 1~2) . But the zinc coating that is performed under optimal pulse reverse current conditions is uniform, fine and bright with an average grain size of 31 nm in the basic sulfate bath with grain refiner additive 1 g/L. This nanocrystalline zinc coating exhibits good reproducibility and ductility properties on mild steel sheets and mild steel wires, as well as better corrosion resistance than conventional coarse?grained zinc coating.
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