Hot-dip galvanizing with electroless ni pre-plating method for controlling thickness of silicon-containing active steel plating

Abstract

The invention discloses an electroless nickel pre-plating and hot post-galvanizing method for controlling the coating thickness of the silicon-containing reactive steel, which means first performing electroless nickel plating and then hot dip galvanizing on a silicon-containing reactive steel part. The electroless nickel pre-plating and hot post-galvanizing method comprises the following processes: (1) doing pretreatment on the surface of the silicon-containing reactive steel part before electroless nickel plating; (2) carry out electroless nickel plating on the surface of the silicon-containing reactive steel part, wherein, the nickel salt used is NiSO4 x 6H2 O, the reducing agent is NaH2PO2 x H2O, and the complexing agent is C6H5Na3O7 x 2H2O; (3) after drying the silicon-containing reactive steel part undergoing electroless nickel plating, conducting hot dip galvanizing on the reactive steel part. The electroless nickel pre-plating and hot post-galvanizing method for controlling the coating thickness of the silicon-containing reactive steel has the advantages of effectively controlling the coating of the hot galvanized silicon-containing reactive steel from thickening exceedingly, thus obtaining a coating with appropriate thickness, smooth surface and good adhesivity, consuming less nickel, and accomplishing the goal of preventing the hot galvanized coating of the silicon-containing reactive steel from excessively thickening by electrolessly plating a nickel coating with a thickness of 3 to 4 microns on the reactive steel part. Moreover, the pre-plate nickel coating can prevent the iron in steel part from dissolving in the zinc bath, thus greatly reducing the formation amount of zinc dross, and reducing the loss of zinc.

Description

technical field [0001] The invention relates to a method for hot-dip galvanizing of iron and steel parts, and more specifically, the invention relates to a method for controlling the thickness of the hot-dip galvanizing layer of silicon-containing active steel. Background technique [0002] Hot-dip galvanizing is a simple and effective steel protection process. It is widely used in the protection of steel components. It is an effective protection method to ensure the corrosion resistance of steel products, prolong the service life and reduce economic losses. During hot-dip galvanizing, silicon in steel will significantly increase the reactivity of iron and zinc, so it is also called active steel. Active steel plated parts tend to have dark, over-thick and poorly adhered coatings, which significantly reduce product quality. In order to solve the coating quality problems of silicon-containing active steel in conventional hot-dip galvanizing methods, various galvanizing techno...

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Problems solved by technology

But, there are some problems in this method in practical application: (1) need often detect the nickel concentration in the plating bath, along with the concentration of nickel in the plating bath constantly reduces, need regularly to add zinc-nickel master alloy in the plating bath, and It is necessary to smelt zinc-nickel master alloy specially; (2) the solubility of iron in zinc is reduced due to the presence of nickel in the plating bath, which increases the formation of iron-nickel-zinc ternary zinc slag in the plating bath, and due to the nickel in the zinc slag The nickel content is much higher than the nickel content in the plating bath, which reduces the efficiency of nickel use; (3) the zinc-nickel alloy plating bath is effective for steel with a silicon content of ≤0.25%, while for high-silicon steel with a silicon content of >0.25%, control Coating growth effect is not obvious

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