Environment-friendly composite colorful passivating solution and preparation method thereof

Abstract

The invention discloses an environment-friendly composite colorful passivating solution and a preparation method thereof and belongs to the technical field of surface treatment of metal materials. Thepassivating solution comprises the components of 17-22 g/L of sodium silicate, 4-8 g/L of sodium molybdate, 6-10 g/L of sodium nitrate, 3-7 mL/L of hydrogen peroxide, 1-3 g/L of potassium fluoride, 2-6 mL/L of nitrilotrimethylene triphosphonic acid, 2-4 g/L of sodium gluconate, 2-4 mL/L of tartaric acid and the balance water, wherein the pH value of the passivating solution is 2.0-2.5. The preparation method of the passivating solution comprises the steps that the sodium silicate, the sodium molybdate, the sodium nitrate, the potassium fluoride, the nitrilotrimethylene triphosphonic acid, thesodium gluconate, the tartaric acid and the hydrogen peroxide are sequentially added into deionized water to be evenly mixed; the water with the constant volume is added to the needed volume; and sulfuric acid is used for adjusting the pH value to be 2.0-2.5, and thus environment-friendly composite colorful passivating solution is obtained. A galvanized layer passivated film treated by the passivating solution is colorful, bright in color, even in film forming and excellent in corrosion resistant performance; the passivating solution does not contain trivalent chromium, hexavalent chromium and other harmful substances and is environmentally friendly, free of pollution, simple in passivating process and high in passivating efficiency, and the corrosion resistance of a film layer is good.

Description

technical field [0001] The invention relates to an environment-friendly composite colored passivation solution and a preparation method thereof, belonging to the technical field of metal material surface treatment. Background technique [0002] Electrogalvanizing is one of the important methods in the surface coating protection method. This method covers the surface of the protected material with poor corrosion resistance with zinc with good corrosion resistance, and separates the protected material from the corrosive medium to achieve for the purpose of corrosion control. It can not only greatly improve the corrosion resistance of the protected material, but also the electroplating technology has the advantages of simple equipment, easy operation and low cost. Make this method the most common and important anti-corrosion method. If there is no good post-treatment after zinc electroplating, the coating will soon become dark and white corrosion products will appear one afte...

AI Technical Summary

Problems solved by technology

[0003] In the common chromium-free passivation process, the corrosion resistance of organic passivation is good, but the adhesion and heat resistance are poor, and the corrosion resistance of single inorganic passivation is slightly worse than that of organic passivation

Inorganic and organic composite passivation is the synergistic corrosion inhibition and performance complementation between inorganic molecules or ions and organic molecules, which further improves the corrosion resistance of the passivation film. It should be pointed out that there are still many problems in using these chromium-free passivation technologies alone. Defects, or poor corrosion resistance, or poor appearance, or poor electrical grounding performance, or high price, it is difficult to meet the application requirements

[0004] At present, the silicate passivation in the chromium-free color passivation system has a good application prospect, but the stability and corrosion resistance need to be improved; the molybdate system has a good corrosion retarding effect and low toxicity, but the film thickness requires Too high, high cost; rare earth metal salt system, low toxicity, good stability, good corrosion inhibition, but high cost; titanium salt system has high corrosion resistance, but high cost, and many components; organic system anti-corrosion High resistance, but there are many types of film-forming agents, the passivation process is complicated, and the passivation cost is high