CN103849864B - A kind of galvanized chromium-free color passivation solution, preparation and using method - Google Patents

Abstract

The present invention relates to a kind of galvanized chromium-free color passivation solution, preparation and using method, belong to technical field of anticorrosion.The composition of this passivating solution is 20～30g/L sodium silicate, 15～25g/L zinc nitrate, 10～30mL/L nitric acid, 6～10g/L sodium gluconate, 8～12g/L potassium fluoride, 4～6mL/L sulphuric acid, and remaining is water, and pH is 1.5～2.5.Mixing concentrated sulphuric acid, concentrated nitric acid, zinc nitrate, sodium gluconate and sodium fluoride successively in the sodium silicate solution configured according to the composition proportion of this passivating solution, finally adjusting pH value with dilute sulfuric acid or diluted sodium hydroxide solution is 1.5～2.5.To put into after iron and steel parts pretreatment in this passivating solution, rinse well with clear water after soaking 20～60 seconds under conditions of 35～45 DEG C and be dried.Chromium-free passivation liquid is inorganic salt, decreases the pollution of discharge of wastewater, reduces the injury to human body；Meet electrogalvanizing iron and steel parts performance and the silicate colorful passivating process of appearance requirement.

Description

A kind of chromium-free color passivation solution for galvanizing, its preparation and application method

technical field

The invention relates to a chrome-free color passivation solution for galvanizing, preparation and use methods, and belongs to the technical field of anticorrosion.

Background technique

The cost of corrosion to our economy is enormous. The metal materials and equipment scrapped due to corrosion are equivalent to more than 20% of the production in the world every year. Various anti-corrosion measures have emerged, among which galvanized passivation anti-corrosion is the most widely used in various metal protection industries, such as aerospace materials, electronic equipment, automobile industry, hardware, electromechanical, etc.

At present, most galvanized steel parts on the market are hexavalent chromium or trivalent chromium passivation treatment, but hexavalent chromium is very harmful to human health, has serious pollution to the environment, and does not meet the national emission standards; trivalent chromium passivation The chemical toxicity is small, and the trivalent chromium passivation process has been widely used at home and abroad. However, trivalent chromium is easily transformed into hexavalent chromium during use, which does not solve the problem in terms of environmental protection.

Therefore, completely chromium-free passivation technology will become the mainstream technology in the future. At present, the main research on chromium-free passivation technology at home and abroad includes molybdate passivation, silicate passivation, titanium salt passivation, rare earth alloy passivation, organic matter passivation and phytic acid passivation, but there is no one without passivation. Chromium passivation can completely replace the traditional chromate passivation process in production. The passivation film formed by molybdate passivation is rich in color, but the cost is high and maintenance is difficult. Titanium salt passivation has good corrosion resistance, but low film forming efficiency. Rare earth passivation has good corrosion resistance, but generally the time required for passivation is too long, and the passivation time is more than 1 day to meet the performance requirements. Silicate passivation is clean and environmentally friendly, has good corrosion resistance and low cost, and is the most promising chromium-free passivation technology.

Contents of the invention

In order to overcome the deficiencies of the existing passivation technology, the present invention provides a chromium-free galvanized passivation solution, its preparation and use method. damage; silicate color passivation process that meets the performance and appearance requirements of electro-galvanized steel parts.

The composition of the zinc-plated chrome-free color passivation solution of the present invention is: 20～30g/L sodium silicate, 15～25g/L zinc nitrate, 10～30mL/L nitric acid, 6～10g/L sodium gluconate, 8～ 12g/L potassium fluoride, 4~6mL/L sulfuric acid, the rest is water, and the pH is 1.5~2.5.

The preparation method of the zinc-plated chromium-free colored passivation solution of the present invention is: according to the component distribution ratio of the passivation solution, mix concentrated sulfuric acid, concentrated nitric acid, zinc nitrate, sodium gluconate and fluorine in the sodium silicate solution in order. Sodium chloride, and finally adjust the pH value to 1.5-2.5 with dilute sulfuric acid or dilute sodium hydroxide solution.

The concentration of the concentrated sulfuric acid is 98wt%.

The concentration of described concentrated nitric acid is 65wt%.

The concentration of the dilute sulfuric acid or dilute sodium hydroxide is 10-12 g/L.

The method of using the chromium-free galvanized color passivation solution of the present invention is as follows: put the steel parts into the passivation solution after pretreatment, soak for 20-60 seconds under the condition of 35-45°C, rinse and dry with clean water That's it.

The pretreatment process of the iron and steel parts is as follows: chemical derusting, electrolytic degreasing, activation treatment and light treatment are carried out in sequence, and each process must be rinsed with clean water after treatment.

The activation treatment is to use a concentration of 1 to 3wt% HCL washes the surface of steel parts.

The beneficial effects of the present invention are: the preparation of the passivation solution is simple, the composition of the passivation solution is chromium-free and non-toxic chemicals, environmentally friendly and green, in line with the national waste liquid discharge standard, the damage to the human body and the environment is reduced, and the passivation solution has good stability After passivation, the passivation film presents a bright color, and the gloss and uniformity of the passivation film are excellent, which can meet the requirements of the market for the appearance of the passivation film. The passivation process is simple, operable and suitable for industrial production.

detailed description

The present invention will be further described below in combination with specific embodiments.

Embodiment 1: The composition of the chromium-free galvanized passivation solution of this embodiment is: 20g/L sodium silicate, 15g/L zinc nitrate, 15mL/L nitric acid, 10g/L sodium gluconate, 12g/L fluoride Potassium, 4mL/L sulfuric acid, the rest is water, and the pH is 1.5.

The preparation method of the zinc-plated chromium-free color passivation solution of the present embodiment is: according to the component ratio of this passivation solution, mix concentrated sulfuric acid, concentrated nitric acid, zinc nitrate, sodium gluconate and Sodium fluoride, and finally adjust the pH to 1.5 with dilute sulfuric acid or dilute sodium hydroxide solution. The concentration of concentrated sulfuric acid is 98wt%, the concentration of concentrated nitric acid is 65wt%, and the concentration of dilute sulfuric acid or dilute sodium hydroxide is 12g/L.

The usage method of the chromium-free galvanized color passivation solution of the present embodiment is as follows: the iron and steel parts are subjected to chemical derusting, electrolytic degreasing, activation treatment and light treatment in sequence, each process is finished and rinsed with clean water, and then Put it into the passivation solution, soak it for 40 seconds under the condition of 35°C, then rinse it with clean water and dry it. Activation treatment is to use a concentration of 3wt% HCl rinses the surface of steel parts.

The appearance of the zinc coating after passivation treatment using this passivation solution is a uniform iridescent passivation film, and the white rust time exceeds 76 hours through a neutral salt spray test.

Embodiment 2: The composition of the chromium-free galvanized color passivation solution of this embodiment is: 30g/L sodium silicate, 25g/L zinc nitrate, 30mL/L nitric acid, 6g/L sodium gluconate, 10g/L fluoride Potassium, 5mL/L sulfuric acid, the rest is water, pH is 2.

The preparation method of the zinc-plated chromium-free color passivation solution of the present embodiment is: according to the component ratio of this passivation solution, mix concentrated sulfuric acid, concentrated nitric acid, zinc nitrate, sodium gluconate and Sodium fluoride, and finally adjust the pH to 2 with dilute sulfuric acid or dilute sodium hydroxide solution. The concentration of concentrated sulfuric acid is 98wt%, the concentration of concentrated nitric acid is 65wt%, and the concentration of dilute sulfuric acid or dilute sodium hydroxide is 10g/L.

The usage method of the chromium-free galvanized color passivation solution of the present embodiment is as follows: the iron and steel parts are subjected to chemical derusting, electrolytic degreasing, activation treatment and light treatment in sequence, each process is finished and rinsed with clean water, and then Put it into the passivation solution, soak it for 20 seconds under the condition of 40°C, rinse it with clean water and dry it. Activation treatment is to adopt the concentration of 1wt% HCl rinses the surface of steel parts.

The appearance of the zinc coating after passivation treatment using this passivation solution is a uniform iridescent passivation film, and the white rust time exceeds 75 hours through a neutral salt spray test.

Embodiment 3: The composition of the chromium-free galvanized color passivation solution of this embodiment is: 26g/L sodium silicate, 22g/L zinc nitrate, 10mL/L nitric acid, 8g/L sodium gluconate, 8g/L fluoride Potassium, 6mL/L sulfuric acid, the rest is water, and the pH is 2.5.

The preparation method of the zinc-plated chromium-free color passivation solution of the present embodiment is: according to the component ratio of this passivation solution, mix concentrated sulfuric acid, concentrated nitric acid, zinc nitrate, sodium gluconate and Sodium fluoride, and finally adjust the pH to 2.5 with dilute sulfuric acid or dilute sodium hydroxide solution. The concentration of concentrated sulfuric acid is 98wt%, the concentration of concentrated nitric acid is 65wt%, and the concentration of dilute sulfuric acid or dilute sodium hydroxide is 11g/L.

The usage method of the chromium-free galvanized color passivation solution of the present embodiment is as follows: the iron and steel parts are subjected to chemical derusting, electrolytic degreasing, activation treatment and light treatment in sequence, each process is finished and rinsed with clean water, and then Put it into the passivation solution, soak it for 60 seconds under the condition of 45°C, rinse it with clean water and dry it. Activation treatment is to use a concentration of 2wt% HCl rinses the surface of steel parts.

The appearance of the zinc coating after passivation treatment using this passivation solution is a uniform iridescent passivation film, and the white rust time is more than 78 hours after the neutral salt spray test.

The specific embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the art .

Claims (6)

1. A chrome-free color passivation solution for galvanizing is characterized in that the composition of the passivation solution is: 20～30g/L sodium silicate, 15～25g/L zinc nitrate, 10～30mL/L nitric acid, 6～ 10g/L sodium gluconate, 8-12g/L potassium fluoride, 4-6mL/L sulfuric acid, the rest is water, and the pH is 1.5-2.5. 2. a configuration method of chromium-free galvanized color passivation solution for galvanizing as claimed in claim 1, is characterized in that concrete method is: mix in the sodium silicate solution that configures successively according to the composition distribution ratio of this passivation solution Concentrated sulfuric acid, concentrated nitric acid, zinc nitrate, sodium gluconate and potassium fluoride, and finally adjust the pH value to 1.5-2.5 with dilute sulfuric acid or dilute sodium hydroxide solution. 3. The method for configuring the chrome-free colored passivation solution for galvanizing according to claim 2, characterized in that: the concentration of the dilute sulfuric acid or dilute sodium hydroxide is 10-12 g/L. 4. A method for using the chrome-free color passivation solution for galvanizing as claimed in claim 1 or 2, characterized in that the specific method is: put into the passivation solution after the pretreatment of the steel parts, within 35～ Soak at 45°C for 20-60 seconds, then rinse with clean water and dry. 5. the using method of galvanized chromium-free color passivation solution according to claim 4 is characterized in that the operation of pretreatment of iron and steel parts is: carry out chemical rust removal, electrolytic degreasing, activation treatment and light treatment successively, each Rinse with clean water after each process. 6 . The method for using the chrome-free color passivation solution for galvanizing according to claim 4 , characterized in that: the activation treatment is to use HCl with a concentration of 1 to 3 wt % to rinse the surface of steel parts.