摘要：热浸镀锌铝合金镀层是现代工业大量使用的金属镀层。由于腐蚀问题遍及国民经济和人类活动的各个领域，大量的工程构件、设备和设施因腐蚀而失效，给国家带来巨大的经济损失。目前我们使用最广泛的是70年代问世的Galvalume铝锌硅热镀合金（55％Al-43.4％Zn-1.6%Si）。但是，Galvalume合金镀层过厚、熔池中渣量过多的问题严重影响了产品质量。研究表明，底渣形成主要原因是熔池中过饱和的铁含量及熔池密度过低。通过降低锌铝熔体中铝含量的方法，可以有效降低浸镀温度，从而降低锌池中的铁含量及铁、铝之间的放热反应，持续有效地降低锌池中铁的溶解度，减少锌池中的锌渣生成量，并使锌池中有限的锌渣由底渣转化为浮渣，即具有使浸镀过程中产生的作为锌渣主要成分的FeAl3由底渣变成浮渣的功能。本实验通过合金化的方法，在Zn-30%Al熔池中加入合金元素Mg和Si，以期找到在降低铝含量的前提下，有效控制合金镀层厚度并提高镀层耐蚀性能。
本文利用扫描电镜、能谱仪研究了560℃情况下，Q235钢在Zn-30%Al-x%Mg、Zn-30%Al-1.1%Si-x%Mg等不同熔池中浸镀不同时间后镀层合金层组织生长的变化规律；利用电化学方法，研究了Mg、Si协同作用对热浸Zn-30%Al-1.1%Si-1.0%Mg镀层耐蚀性的影响。获得如下结果：
1、在Zn-30%Al熔池中Mg的加入有利于减缓浸镀过程中的放热反应，对合金层的生长具有明显的抑制作用。
2、在Zn-30%Al熔池中加入Si元素后，可以减缓铁铝之间的放热反应，有效减薄合金层厚度；同时随着合金元素Si的加入，会改变钢基界面生成合金相的种类，由Zn-30%Al-x%Mg合金层的FeAl3相转变为Zn-30%Al-1.1%Si-x%Mg合金层的τ5C相。
3、在Zn-30%Al-1.1%Si熔池中加入Mg元素，Mg、Si协同作用能进一步减薄合金镀层，实验时加入1%Mg效果最好。当Mg超过一定含量，则会使得熔池流动性变差，产生漏镀现象。
4、Mg、Si协同作用对镀层耐蚀性实验表明Zn-30%Al-1.1%Si-1.0%Mg镀层的耐蚀性优于Galvalume。
关键词：合金层，耐蚀性，动力学，Mg，Si
Abstract: Hot-dip galvanized aluminum alloy coating is the extensive use of modern industrial metal coating. Corrosion problems throughout the national economies and human activities in various fields of engineering components, equipments and facilities due to corrosion and failure to bring about huge economic losses to the state. Currently the most widely used is the advent in the 1970s, Galvalume aluminum zinc silicon alloy (55% Al-43.4% Zn-1.6% Si). Galvalume alloy coating is too thick, however, the excessive amount of slag of molten pool seriously affect the quality of the product. Studies have shown that the bottom ash formed mainly due to the molten bath saturated iron content and low bath density. By reducing the aluminum content in the melt of zinc aluminum, can effectively reduce the dip temperature, thereby reducing the zinc pool iron content and the exothermic reaction between the iron, aluminum, and continue to reduce the solubility of zinc in the pool of iron, to reduce zinc pool zinc dross generation, limited zinc pool and zinc ash, bottom ash is converted to the scum, that is to dip the bottom ash as a main component of the zinc slag FeAl3 become dross function. In this study, by alloying, in Zn-30% Al bath by adding alloying elements Mg and Si, in order to find the premise of lower aluminum content, effective control of the alloy coating thickness and coating corrosion performance.
By using scanning electron microscopy, energy dispersive spectroscopy to study the case of 560 ℃, Q235 steel in Zn-30% Al-x% of Mg, Zn-30% Al-1.1% Si-x% Mg bath immersed plated at different times after the coating alloy layer growth variation. By using electrochemical methods, the study of Mg, Si synergistic effect on the corrosion resistance of hot dip Zn-30% Al-1.1% Si-1.0% Mg coating. The following results:
1、In Zn-30% Al bath of Mg join conducive to slow exothermic reaction in the dip, significantly inhibited the growth of the alloy layer.
2、Si elements in Zn-30% Al bath, can slow the exothermic reaction between the Fe-Al and effective reduce alloy layer thickness; at the same time with the addition of alloying elements Si steel substrate interface generation alloy phase species, the Zn-30% Al-x% Mg alloy layer FeAl3 into the Zn-30% Al-1.1% Si-x% Mg alloy layer τ5C phase.
3、By mg element in the Zn-30% Al-1.1% Si bath, Mg, Si synergistic effect can further thin of the alloy coating, experiment by adding 1% of Mg is the best. When Mg exceeds a certain content will be making the weld pool fluidity variation to produce uncoated phenomenon.
4、Mg, Si synergistic effect on the corrosion resistance experiments show that the corrosion resistance of Zn-30% Al-1.1% Si-1.0% Mg coating is better than Galvalume.
Key word: alloy layer，corrosion resistance，dynamics，Mg，Si
