Effect of Zn-Fe alloy layer in coating on corrosion performance of steel wires for offshore engineering
Composition and content of Zn-Fe alloy phase in hot-dip galvanized steel wire coating have significant impact on corrosion performance of coating.Morphology and thickness of Zn-Fe alloy layer is analyzed,results show that corrosion resistance of galvanized steel wire increases with total thickness of alloy layer and pure zinc layer.While the Zn-Fe alloy layer is not the thicker the better,and the best thickness is 6～7.5 μm.At this time,proportion of brittle phaseΓ(Fe5Zn21)and soft brittle phase ξ(FeZn13)in alloy layer is relatively small,there are no cracks,looseness,or coarse structure in alloy layer.Strictly control proportion of zinc and iron elements in alloy layer.Mass fraction of iron elements in pure zinc layer is best controlled no more than 1.5％,while Fe element content in Zn-Fe alloy layer is best controlled no more than 8％,ensuring optimal phase 8(FeZn7)ratio is 80％～85％.At this time,protective performance of alloy layer is the best.
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