碱性锌镍合金电镀中NiSO_4·6H_2O浓度对镀层的影响

Effect of Nickel Sulfate Concentration in Plating Bath on Morphology and Corrosion Resistance of Zinc-Nickel Alloy Coatings Electroplated in Alkaline Bath

过去,就碱性锌镍合金电镀液中镍离子含量对镀层镍含量、形貌及耐蚀性的影响研究不够。考察了镀液中NiSO4.6H2O浓度对碱性锌镍合金镀层质量的影响,利用扫描电镜(SEM)、能谱仪和塔菲尔曲线分析了镀层的镍含量、形貌和性能。结果表明:锌镍合金镀层中镍含量随镀液中NiSO4.6H2O浓度的增加而增大,当NiSO4.6H2O低于8 g/L时,镀层镍含量低,晶粒粗大,不光亮;高于8 g/L时镀层镍含量较高,晶粒粗大、出现瘤状物,镀层会出现开裂现象;浓度为8 g/L时效果最好,镀层镍含量为12.56%,镀层平整、致密、光亮,具有良好的耐蚀性能。

Electroplated Zn-Ni alloy coatings were prepared from alkaline bath containing different concentration of nickel sulfate(NiSO4.6H2O).The morphology and composition of as-plated Zn-Ni alloy coatings were analyzed by scanning electron microscopy and energy dispersive spectrometry.The Tafel curves of as-plated alloy coatings were measured.The effect of concentration of NiSO4.6H2O in plating bath on the quality of the alloy coatings was investigated.It was found that the Ni content in the alloy coatings increased with increasing concentration of NiSO4.6H2O in the plating bath.The Zn-Ni alloy coatings obtained from the plating bath with less than 8g/L NiSO4.6H2O contained low content of Ni and consisted of coarse grains,showing non-bright appearance.When the concentration of NiSO4.6H2O in the plating bath was above 8g/L,corresponding Zn-Ni alloy coatings contained higher content of Ni and also consisted of coarse grains,accompanied by occurrence of tumor-like substance and cracking.It was suggested to control the concentration of NiSO4.6H2O in the plating bath as 8g/L,corresponding Zn-Ni alloy coating was smooth,compact and bright,containing 12.56% Ni and showing good corrosion resis tance.