| In order to develop a new type of alloy coating with excellent properties, in this paper,the Zn-0.02%Al, Zn-0.5%Al, Zn-5%Al and Zn-5%Al-0.05%RE alloy coatings were used asobjects of study, the effects of the Al and RE elements in the zinc bath on the microstructureand the properties of hot-dip galvanizing coatings were investigated by optical microscopy,SEM, EDS, hardness test, neutral salt spray test, full immersion corrosion test and orthogonalexperiment. A new type of flux and plating process of electrolytic activation were developed,and a Zn-Al-RE alloy coating and production process were exploited.The best composition of flux are550g/LZnCl2,100g/LNH4Cl,20g/LSnCl2,15g/LNa3AlF6,15g/LNaF and10g/LCeCl3. The plating process of electrolytic activation isproceeded at70℃for2min, electric current is0.5A. The plating coating surface is uniform,and there are no defects of leakage and zinc melanoma in coatings.The coating lightness is excellent when the Al content is0.02%, and the coating lightnessis decline with increasing the Al content. Accession to the0.05%RE in the5%Al in zinc bath,the surface brightness of Zn-5%Al-0.05%RE alloy coating got is favorable.With increasing Al content, the surface hardness of Zn-Al alloy coatings increases, thecoating thickness reduces firstly and then increases. The addition of RE can increase thehardness of the coating, and the coating thickness is reduction.The wear proof time increase firstly and then decreases for Zn-Al alloy coatings alongwith the increase of Al content，and the addition of RE in Zn-Al alloy coating can decrease thefriction coefficient and increase the wear proof time obviously.The addition of Al element in the zinc bath can inhibite the growth of brittle ζ phase,promote the nucleation and growth of plastic δ phase, and get a coating with suitablethickness. The addition of RE element in Zn-5%Al alloy bath can refine grains, compactmicrostructure, suppress intergranular corrosion, and improve the corrosion resistance. |
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