Ni含量对Zn-Ni合金镀层的耐蚀性影响

EFFECT OF Ni CONTENT ON CORROSION RESISTANCE OF ELECTROPLATED COATINGS OF Zn-Ni ALLOYS

采用中性盐雾试验对Zn-Ni合金镀层的耐蚀行为进行了研究,并用扫描电镜、辉光放电光谱仪和X射线衍射仪等手段分析了不同Ni含量的Zn-Ni合金镀层的微观形貌与结构、成分变化规律以及腐蚀产物.结果表明：（1）随着镀层的不断沉积,Ni的含量先增加后减小,在镀层中出现Ni的富积层;（2）Ni含量在5%～15%范围内时,Zn-Ni合金镀层的相结构体现出很复杂的结构特征;（3）经过钝化处理的Zn-Ni合金镀层的耐蚀性远高于镀Zn钝化层、镀Cd钝化层和Cd-Ti合金镀层的耐蚀性;（4）Zn-Ni合金镀层腐蚀产物主要是ZnO和ZnCl2.4Zn（OH）2,并且含有少量的2ZnCO3.3Zn（OH）2.

Tbe surface morphology and microstructure, chemical compositions and corrosion products of Zn-Ni alloy coatings with different Ni contents were examined by means of SEM, glow discharge optical emission spectrometry and XRD. The corrosion resistance of Zn-Ni alloy coatings was studied by neutralized salt spray test. The results show that when the thickness of Zn-Ni alloy coatings increases, the Ni content increases first and then decreases. There is an enrichment of Ni in the coatings. The Zn-Ni alloy coatings exhibit different and sophisticated alloy phase constituents when the Ni contents are between 5% to 15%. The corrosion resistance of a passivated Zn-Ni alloy coating is much better than that of the passivated ones such as Zn, Cd and alloys of Cd-Ti. The corrosion products of Zn-Ni alloys are mainly made of ZnO, ZnCl2.4Zn（OH） 2 and a little 2ZnCO3.3Zn（OH） 2.