Hot dip galvanizing coating chromate-free passivation agent and preparation method thereof

Abstract

The invention relates to a hot dip galvanizing coating chromate-free passivation agent and a preparation method thereof. Preparation of 1 l of the passivation agent is taken as an example, and the formula of the passivation agent comprises 8-40 g of sodium silicate, 20-40 g of sodium tungstate, 3-10 g of fluotitanic acid, 20-60 g of hydrogen peroxide, 3-7 mL of nitric acid, 3-7 mL of phosphoric acid, 1-6 g of film formation accelerant and the balance water. At least one of cobaltous sulfate and nickel sulfate serves as the film formation accelerant. The passivation agent is low in cost and simple in process, the environment cannot be danaged, and the passivation agent is more suitable for industrial application and popularization. A passivation film layer formed through the passivation agent is even, compact, bright, attractive and good in corrosion resistance.

Description

technical field [0001] The invention relates to surface treatment technology, in particular to a chromium-free passivator for a hot-dip galvanized layer and a preparation method thereof. Background technique [0002] With the progress of society and industrial development, the requirements for the surface properties of various equipment parts are getting higher and higher. Improving the surface properties of materials will effectively prolong their service life, save resources, increase productivity, and reduce environmental pollution. The biggest advantage of surface treatment technology is that it can prepare a thin layer of surface function that is superior to the performance of the base material in a variety of ways, so that the parts have higher wear resistance, self-lubrication, corrosion resistance and high temperature resistance than the base material. and other capabilities. Surface treatment technology includes many kinds, chrome-free passivation is one of them. ...

AI Technical Summary

Problems solved by technology

The disadvantage of the second type of chromium-free passivation agent is that the passivation film layer of the workpiece is thin and has poor corrosion resistance.

The shortcoming of this chromium-free passivating agent is that in use, there will be uneven silicate passivation film, large granular substances appear on the surface, and there are cracks in the film (such as figure 2 ), the roughness and unevenness of the microstructure directly lead to the poor corrosion resistance of the surface film of the hot-dip galvanized product, the time of rusting in salt water is accelerated, and the rusting area is rapidly expanded

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