Q235上电弧喷涂Zn55Al涂层在3.5wt%溶液中的腐蚀行为研究

本文使用电弧喷涂通过包套挤压+拉拔的方法制备的Zn55Al伪合金丝材成功的在Q235钢上喷涂出了Zn55Al涂层。通过扫描电镜和微区XRD研究了Zn55Al 伪合金丝材的显微结构。通过浸泡腐蚀实验和电化学方法研究了Zn55Al涂层、Zn15Al涂层和 Al涂层的腐蚀行为，并对比了三种涂层之间的差异。结果表明Zn55Al伪合金丝材由纯锌和纯铝组成，在整个成型过程中没有产生合金化。Zn55Al涂层由层片状的富锌相和富铝相组成。经过20天的浸泡实验，Zn55Al涂层形成了一层致密的钝化膜，比其他两种涂层有更好的耐腐蚀性。Zn55Al涂层的自腐蚀电位大约是-1.25v,高于Zn15Al涂层低于纯Al涂层和Q235基体.电偶腐蚀实验表明，Zn55Al涂层比Zn15Al涂层具有更好的点虎穴保护作用。这些结果说明Zn55Al涂层具有更好的耐腐蚀性和可以给Q235基体提供更强的电化学保护.本文也讨论了Zn55Al涂层的的腐蚀机理。

Corrosion behaviour of arc sprayed high Al content of Zn55Al coatings on Q235 steel in 3.5 wt% NaCl solution

In this work, a Zn55Al coating was deposited on Q235 steel by arc spraying high Al content Zn55Al pseudo-alloy wires formed by multi-core canned hot extrusion and a cold drawing method. The microstructure of the Zn55Al pseudo-alloy wire was investigated by scanning electron microscopy (SEM) and micro-region X-ray diffraction (Micro-XRD). The corrosion behaviour of the Zn55Al coating and pure Al coating as well as the Zn15Al coating were investigated by an immersion corrosion test and electrochemical measurements, and the difference between the coatings was also assessed. The results indicated that Zn55Al pseudo-alloy wires were composed of pure Zn and pure Al. An alloying phenomenon did not occur in the whole formation process. The Zn55Al coating that contained Zn-rich phases and Al-rich phases exhibited an obvious lamellar structure with a few holes and gaps. After 20 days of immersion, it was found that the Zn55Al coating formed a dense passive film and had better corrosion resistance than the Zn15Al coating. The corrosion potential (Ecorr) of the Zn55Al coatings was approximately 80 mv, which is more positive than that of the Zn15Al coatings but is more negative than that of the pure Al coatings and the Q235 substrate. The results of galvanic corrosion test also showed that the Zn55Al coating can provide better electrochemical protection than Zn15Al coating to the Q235 substrate. This suggested that Zn55Al coating displays not only a better corrosion resistance but also a stronger electrochemical protection to the Q235substrate. The protective mechanisms of the Zn55Al coating were also discussed.