Magnesium oxidation protection method for hot-dip galvanized aluminum magnesium alloy coating product

Abstract

The invention discloses a magnesium oxidation protection method for a hot-dip galvanized aluminum magnesium alloy coating product. The magnesium oxidation protection method comprises the following steps that (1), a protection cover is additionally arranged above a zinc-aluminum-magnesium pot, and the size and the shape of a protection cover body can be customized according to the spatial positions of zinc-aluminum-magnesium pot areas of different galvanizing production lines; (2), nitrogen brought by an air knife in the production process is fully utilized and collected in the protection cover, and the liquid level of a zinc pot and the surface of strip steel are protected; and (3), a nitrogen supplementing hole is additionally formed in the protection cover, the nitrogen supplementing amount of the supplementing hole is controlled according to the pressure detection value in the protection cover, and gas in the cover is kept in a positive pressure state. N2 brought by the air knife and supplemented N2 are collected in the box body to keep positive pressure. N2 in the protection cover reduces the influence of O2 oxidation in air on the liquid level of the zinc pot and the surface of the strip steel, so that the purpose of reducing scums on the surface of the plating liquid level and avoiding the quality problems of surface defects such as surface black spots caused by Mg oxidation on the surface of the strip steel is achieved, and the product quality is improved.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a magnesium oxidation protection method for a hot-dip galvanized aluminum-magnesium alloy coating product. Background technique [0002] Compared with traditional coatings such as hot-dip galvanizing, hot-dip galvanized aluminum-magnesium alloy coating has better corrosion resistance, and because the zinc-aluminum-magnesium alloy coating is relatively thin and dense, it is not easy to peel off the coating; The protection performance of cuts and defects is better; it also has good corrosion resistance in harsh corrosive environments, and is an alloy coating product with market prospects. [0003] The Mg in the hot-dip galvanized aluminum-magnesium alloy coating comes from the Mg element contained in the plating solution, which is added through the zinc-aluminum-magnesium alloy ingot. The alloy layer of hot-dip galvanized aluminum-magnesium products contains an appropriate amou...

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Problems solved by technology

[0005] When the Mg content is within 1%, the zinc-aluminum-magnesium solution in the zinc pot has good fluidity, and the coating surface is bright and smooth; when the Mg content is 1-3%, the coating surface appears dark and not smooth, mainly because the Mg element is too active and easy to mix with air. Oxygen reacts in the coating to form oxides on the surface of the coating; when Mg exceeds 4%, missing coatings often occur after the strip is dipped, and the quality of the coating is poor; prevent the oxidation of Mg in the zinc-aluminum-magnesium alloy coating during the production process. Quality is critical, there is no good solution yet

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