Environment-friendly composite color passivation solution and preparation method thereof

Abstract

The invention discloses an environment-friendly composite color passivation solution and a preparation method thereof, and belongs to the technical field of surface treatment of metal materials. The passivation solution comprises the components of 5-8g/L of tannic acid, 4-8mL/L of titanium trichloride, 4-7mL/L of nitric acid, 15-20mL/L hydrogen peroxide, 2-5mL/ L concentrated sulfuric acid, 8-12mL/L of phosphoric acid, 2-7g/L of sodium silicate, 6-10g/L of potassium fluoride, 2-5mL/L of ascorbic acid, 4-7mL/L of aminotrimethylene fork phosphonic acid, and the balance water, and the pH value is1.5-2.0. A zinc plating coating passivation film treated by the passivation solution is bright in color, uniform in color and film thickness and excellent in corrosion resistance; and the passivationsolution has no trivalent chromium, hexavalent chromium and other harmful substances, environmental protection and no pollution are achieved, the passivation process is simple, the passivation efficiency is high, and corrosion resistance of the film 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] Electro-galvanizing is a commonly used method for metal anti-corrosion, and it is widely used in many fields such as hardware, electromechanical, ships, electronic equipment, aerospace, and offshore platforms. Since the corrosion potential of zinc is negative than that of iron, and it has good corrosion resistance in dry air, when the plated parts come into contact with corrosive media, they will react with zinc first, thus protecting the substrate. However, due to the active nature of zinc, it is easily corroded under hot and humid environmental conditions. If the galvanized workpiece is not post-treated, the coating will quickly darken and produce white corrosion products, which will greatly weaken the anti-corrosion performance of ...

AI Technical Summary

Problems solved by technology

However, silicate passivation has a good application prospect, but the stability and corrosion resistance of the passivation film are poor, and the silicate system needs to be further improved; while the molybdate passivation effect is better, but its cost is high; The cost of rare earth salt passivation system is also high, and the process operation is complicated and the efficiency is low; the appearance of the film obtained by titanium salt passivation is very close to chromate passivation, but the corrosion resistance is poor and far inferior to that of chromate

In the common chromium-free passivation process, organic passivation has better corrosion resistance, but poor adhesion and heat resistance, and the corrosion resistance of single inorganic passivation is slightly worse than organic passivation