Passivation solution and preparation method thereof

Abstract

The invention provides a passivation solution which is prepared by dissolving various raw materials in deionized water. The materials comprise 6-9 g/L of chromium sulfate hexahydrate, 2-4 g/L of cobalt sulfate heptahydrate, 4-8 g/L of sodium chlorate, 2-3 g/L of ammonium fluoride, 1-2 g/L of sulfuric acid, 2-3 g/L of citric acid and the balance water. According to an obtained passivation film, the corrosion resisting property is good, a salt spray test can be kept for 120 h or longer, the workpiece surface has no white rust or white spot, the porosity is low, and no sealing agent is needed for treatment.

Description

technical field [0001] The invention relates to the field of metal surface treatment agents, more specifically, to a passivation solution, a preparation method and a use method thereof. . Background technique [0002] The galvanized layer is one of the most important protective coatings for steel parts. The galvanized layer is very stable in a dry environment, but in a high-temperature and high-humidity environment, the galvanized layer has poor corrosion resistance and is prone to white rust or white spots . Generally, high-concentration or medium-concentration chromate solution is used for passivation to improve the corrosion resistance of the galvanized layer. In recent years, in order to reduce the pollution of hexavalent chromium to the environment and the harm to the human body, the chromate passivation of the zinc coating is developing in the direction of trivalent chromium salt and chromate-free passivation. [0003] Chinese patent application 201210465245.2 discl...

AI Technical Summary

Problems solved by technology

However, the passivation solution is not stable enough during use and has a short service life. The passivation film obtained in the later stage of use has the disadvantages of large void ratio, poor corrosion resistance, and low adhesion.