| Steel and iron have a significant application in architecture, machinery and household electrical. For its great susceptibility to corrosion, hot dip galvanizing technology has been improved the corrosion resistance and prolong the service lifetime. Nowadays, zinc alloy gradually substitutes pure zinc as the coating material.Galfan coating (Zn-5%Al-0.1%RE) is widely applied for hot dip galvanizing due to its special eutectic microstructure which showed good corrosion resistance. In order to improve corrosion resistance of Galfan coating, Zn-Al-Mg-Si-RE alloy coating was studied in the experiment by full-dipping testing and electrochemical test. The results show that the optimizing addition of Mg and Si is0.3%and0.08%respectively in Zn-5%Al alloy, and the results of four levels orthogonal experiment show that that the optimal additions of Al, Mg, Si and RE are4.8%,0.38%,0.076%and0.13%respectively. The Zn-4.8%Al-0.38%Mg-0.076%Si-0.13%RE coating is test by Neutral salt experiments, and the results show the corrosion rate this coating is42.02%higher than Galfan coating. Compared with Galfan coating, the corrosion current of Zn-4.8%Al-0.38%Mg-0.076%Si-0.13%RE coating significantly decree-ses. Therefore, Zn-4.8%Al-0.38%Mg-0.076%Si-0.13%RE coating is a good prospect for industrial application because of its excellent corrosion resistance.Zn/Al/MgZn2eutectic structure is detected in surface of15#coating which shows excellent corrosion resistance, however, the same eutectic microstructure is not detected in surface of13#coating which shows bad corrosion resistance, as SEM and EDS test results, which cause different corrosion resistance of15#coating and13#coating. Corrosion production of coating is characteristic of double layer structure. There is ZnO in surface of Galfan coating, the existence of ZnO decreases corrosion resistance of the coating, however, ZnO is not in optimal coating. XRD test results show that improvement of corrosion resistance in the coating isn’t caused by different corrosion production. After salt corrosion, SEM test results show that uniform corrosion occurs in optimal coating which is smooth surface.In this experiment, an assist technology and promoter for Zn-Al-Mg-Si-RE hot-dipping were investigated to advance the galvanizing process. In addition, the steel plate instrumental device for experimental galvanization was developed, which has the advantages of simplicity of operation, high automatic level, tractable and smaller in investment. |
PDF Full Text Request