Preparation method of chromium-free passivating solution for brass surface

A technology of chromium-free passivation and preparation method, which is applied in the coating process of metal materials, etc., can solve the problems of poor anti-corrosion performance of thick film, influence on appearance aesthetics, environmental pollution, etc., and achieve dense film layer, long anti-discoloration time, Corrosion resistance for long-lasting effect

Inactive Publication Date: 2014-12-31
无锡杨市表面处理科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the appearance of the product treated by this process is golden yellow and has good corrosion resistance, a large amount of chromate or chromium trioxide is used in this process, and the total amount of hexavalent chromium added is as high as about 250 g/ Lift
According to medical data reports, hexavalent chromium is a strong carcinogen, which can also cause respiratory ulcers, perforation of nasal septum, toxic hepatitis, dermatitis, anemia and other diseases, which is very harmful to human health. The allowable discharge of toxic substances is <0.5mg/l, but the concentration of toxic substances in the chromic acid waste liquid is more than 500,000 times higher than the national standard, and it is difficult to recycle it even at a huge cost
The fact that these harmful substances cannot be recycled means that the pollution to the environment cannot be fundamentally solved, and thus the fact that it is harmful to human health cannot be avoided.
In order to solve this problem, some people used tannic acid and dilute chromic acid to treat the surface of brass, but the color of the workpiece after treatment was poor, the resistance to atmospheric corrosion was weak, the product could not be stored and used for a long time, and the raw materi

Method used

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Examples

Experimental program
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Effect test

Example Embodiment

[0009] Example 1

[0010] A method for preparing a chromium-free passivation solution on a brass surface, the passivation solution is composed of: 10 g / L of benzotriazole, 8 g / L of 1-phenyl-5 mercaptotetrazolium, 20 g / L of tartaric acid, Sodium citrate 7g / L, sodium molybdate 5.5g / L, sodium tungstate 4.5g / L, hydrogen peroxide 15ml / L, boric acid 10g / L, sodium silicate 12g / L, sodium dodecyl sulfonate 4g / L , the balance is water; the preparation method of the passivation solution is: adding an appropriate amount of water in the reaction kettle, then adding boric acid and tartaric acid, stirring until dissolved, then warming up to 40 ° C, then adding benzotriazole and 1 -Phenyl-5-mercaptotetrazolium, stir for 10 minutes to make it uniform, then add sodium citrate, sodium molybdate, sodium tungstate, hydrogen peroxide, sodium silicate and sodium dodecyl sulfonate in sequence after cooling to room temperature, After the former substance is dissolved, add the latter substance, stir f...

Example Embodiment

[0011] Embodiment 2

[0012] A method for preparing a chromium-free passivation solution on a brass surface, the passivation solution is composed of: 12 g / L of benzotriazole, 5 g / L of 1-phenyl-5 mercaptotetrazolium, 22 g / L of tartaric acid, Sodium citrate 5g / L, sodium molybdate 6.5g / L, sodium tungstate 3.5g / L, hydrogen peroxide 19ml / L, boric acid 8g / L, sodium silicate 14g / L, sodium dodecyl sulfonate 2g / L , the balance is water; the preparation method of the passivation solution is: adding an appropriate amount of water in the reaction kettle, then adding boric acid and tartaric acid, stirring until dissolved, then warming up to 50 ° C, then adding benzotriazole and 1 -Phenyl-5-mercaptotetrazolium, stir for 6 minutes to make it uniform, then add sodium citrate, sodium molybdate, sodium tungstate, hydrogen peroxide, sodium silicate and sodium dodecyl sulfonate in sequence after cooling to room temperature, After the former substance is dissolved, add the latter substance, stir ...

Example Embodiment

[0013] Embodiment 3

[0014] A method for preparing a chromium-free passivation solution on a brass surface, the passivation solution is composed of: 11 g / L of benzotriazole, 6.5 g / L of 1-phenyl-5 mercaptotetrazolium, and 21 g / L of tartaric acid , sodium citrate 6g / L, sodium molybdate 6.0g / L, sodium tungstate 4.0g / L, hydrogen peroxide 17ml / L, boric acid 9g / L, sodium silicate 13g / L, sodium dodecyl sulfonate 3g / L, the balance is water; the preparation method of the passivation solution is: adding an appropriate amount of water in the reaction kettle, then adding boric acid and tartaric acid, stirring until dissolved, then warming up to 45 ° C, then adding benzotriazole and 1-Phenyl-5-mercaptotetrazolium, stir for 8 minutes to make it uniform, then cool to room temperature and add sodium citrate, sodium molybdate, sodium tungstate, hydrogen peroxide, sodium silicate and sodium dodecyl sulfonate in sequence , add the latter substance after the former substance is dissolved, stir...

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PUM

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Abstract

The invention discloses a preparation method of a chromium-free passivating solution for the brass surface. The preparation method of the passivating solution comprises the following steps: adding a proper amount of water into a reaction kettle, adding boric acid and tartaric acid, stirring until boric acid and tartaric acid are dissolved, heating to 40-50DEG C, adding benzotriazol and 1-phenyl-5-mercaptotetrazole, stirring for 6-10min to make the obtained solution uniform, cooling to room temperature, sequentially adding sodium citrate, sodium molybdate, sodium tungstate, hydrogen peroxide, sodium silicate and sodium dodecyl sulfonate according to a condition that a later substance is added after a previous substance is dissolved, stirring for 13-17min after all above substances are added, adding water to a constant volume, and adjusting the pH value to 2.5-3.5.

Description

technical field [0001] The invention relates to the technical field of surface treatment, in particular to a preparation method of a chromium-free passivation solution for brass surfaces. Background technique [0002] Copper and brass are easily rusted in the atmosphere. For a long time, people have generally used chromic acid passivation process for surface treatment to improve the surface corrosion resistance of copper and brass. Although the appearance of the product treated by this process is golden yellow and has good corrosion resistance, a large amount of chromate or chromium trioxide is used in this process, and the total amount of hexavalent chromium added is as high as about 250 g / Lift. According to medical data reports, hexavalent chromium is a strong carcinogen, which can also cause respiratory ulcers, perforation of nasal septum, toxic hepatitis, dermatitis, anemia and other diseases, which is very harmful to human health. The allowable discharge of toxic sub...

Claims

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Application Information

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IPC IPC(8): C23C22/40
Inventor 潘增炎
Owner 无锡杨市表面处理科技有限公司
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