稀土钇对输电铁塔钢制件热浸镀锌层组织与耐腐蚀性能的影响

Effect of Rare Earth Yttrium on Microstructure and Corrosion Resistance of Zinc Hot Dip Galvanized Layer for Transmission Tower Steel Members

通过稀土元素钇(Y)对Zn-1Mg镀锌液进行熔体变质处理,并采用X射线衍射仪、光学显微镜、扫描电镜、电化学极化腐蚀试验分析了不同Y添加量对镀锌液和钢制件镀锌层的组织形貌、硬度和耐腐蚀性能的影响。结果表明,稀土Y元素以细小颗粒状YZn_(12)相的形式存在于α-Zn晶界处,显著降低α-Zn和Mg_(2)Zn_(11)相尺寸和FeZn_(13)层厚度,提升了总镀锌层厚度。Zn-1Mg-0.2Y镀锌层试样具有最厚的总镀锌层厚度(162μm)、最薄的FeZn_(13)层厚度(85μm)、最高的镀层硬度(312 HV)和最好的耐腐蚀性能(腐蚀速率为162μm/y),这主要归因于稀土元素Y的晶粒和第二相细化及熔体净化作用。因此,稀土Y可以有效提升镀锌层耐腐蚀性能。

Rare earth element(RRE)yttrium(Y)was used for melt modification of Zn-1Mg plating solution,and the effects of different Y additions on the microstructure,hardness,and corrosion resistance of Zn plating solution and steel members were analyzed by X-ray diffractometry,optical microscope,scanning electron microscope,and electrochemical polarization tests.The results revealed that the RRE Y existed in the form of a fine granular YZn_(12)phase at the grain boundary of theα-Zn phase,which significantly reduced the phase size of bothα-Zn and Mg_(2)Zn_(11)phases and the FeZn_(13)layer thickness,and increased the total galvanized layer thickness.The Zn-1Mg-0.2Y galvanized layer sample showed the thickest total galvanized layer thickness(162μm),the thinnest FeZn_(13)layer thickness(85μm),the highest coating hardness(312 HV),and the highest corrosion resistance(corrosion rate is 162μm/y).This is mainly attributed to the grain and second phase refinement and the melt purification by the REE Y.Therefore,RRE Y can effectively improve the corrosion resistance of galvanized coating.