A kind of concentrated solution of trivalent chromium passivating agent and preparation method thereof

Abstract

The invention discloses a trivalent chromium passivator concentrated solution which is prepared from 15-30 parts of chromium dihydrogen phosphate, 5-10 parts of phosphoric acid, 3-10 parts of acidic silica sol, 2-8 parts of low-carbon alcohol, 1-3 parts of sodium nitrate. 0.01-0.2 part of a silane coupling agent, 0.5-2 parts of cobalt nitrate, 0.01-0.2 part of closed synergist vinyl phosphonic acid-acrylic acid copolymer and 30-60 parts of deionized water. A trivalent chromium passivator can be used on the surface of a galvanized steel plate for an automobile so that the surface of the galvanized steel plate can be continuously passivated and form a film, passivation reaction time is short, salt fog resistance time of the film is long, and the trivalent chromium passivator is suitable for dipping of the galvanized steel plate for the automobile and roller painting treatment of workpieces. The trivalent chromium passivator concentrated solution is particularly suitable for the continuous passivation technology.

Description

technical field [0001] The invention relates to a concentrated solution of a trivalent chromium passivation agent, which belongs to the field of metal surface treatment. technical background [0002] Steel parts are usually passivated after electro-galvanizing or hot-dip galvanizing to prevent white rust in a short time. With the rise of my country's automobile industry, the large-scale automobile industry's demand for steel plates continues to increase, and at the same time, the requirements for plate quality and environmental protection are also increasing. This requires that a certain output must be guaranteed and the environmental protection requirements of various countries must be met when processing the plates. The traditional hexavalent chromium color passivation agent has caused serious pollution to the environment, and more and more trivalent chromium passivation agents are used in the surface passivation treatment of automobile steel plates. However, the existin...

AI Technical Summary

Problems solved by technology

However, the existing trivalent chromium passivation process has defects such as unstable product quality, short passivation solution life, difficult control of the passivation process, and poor corrosion resistance of the passivation film.