High corrosion resistant trivalent chromium blue-white deactivator and preparation method thereof

A passivation agent, trivalent chromium technology, applied in the direction of metal material coating process, etc., can solve the requirement gap of high corrosion resistance of corrosion-resistant galvanized workpieces, affect the corrosion resistance of the passivation layer, and affect the passivation layer. Brightness and other issues, to achieve the effect of low passivation cost, improved corrosion resistance, easy preparation and passivation process operation

Active Publication Date: 2008-04-09
深圳市天泽科技实业有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Although the metal galvanized layer passivated by the existing trivalent chromium blue-white passivation agent technology can obtain a certain degree of corrosion resistance and brightness, its corrosion resistance is not as high as that of the current automobile, electronics and other industries for galvanized workpieces. Corrosion requirements still have a large gap
This is mainly related to the rough surface of the passivation layer formed by the existing passivation solution

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Under continuous stirring, the Cr containing chromium 4g 3+ Compound (Cr 2 (SO 4 ) 3 .6H 2 O) Dissolve in 100ml pure water, add 6g malonic acid, 2g ammonium bifluoride and Cobalt containing 0.8g successively 2+ Compound (CoSO 4 .7H 2 O), after the raw material is completely dissolved, heat to 80°C, slowly add 1.5g NaOH raw material within 25min, fully react for 2.5 hours, stop heating and cool to 25°C, add NO 3 - The amount is 2g (NaNO 3 ), add 0.8g formic acid, stir for 15min, add SiO 2 1.6g of low-nano-scale acidic silica sol, stirred for 15 minutes, added pure water to 1000ml, and obtained a high-corrosion-resistant trivalent chromium blue-white passivator.

[0022] When in use, use acid (nitric acid) or alkali (NaOH) to adjust the pH of the passivating agent solution to 2.0, and passivate the galvanized workpiece (galvanized layer thickness 6-10μm, barrel-plated screw) at 25°C, and the passivation time 30 seconds, after passivation is completed, 60 ℃ hot ...

Embodiment 2

[0027] Under continuous stirring, the Cr containing 2g of chromium 3+Compound (CrCl 3 .6H 2 O) Dissolve in 100ml of pure water, add 5g of malonic acid, 1g of ammonium bifluoride and 1g of cobalt in turn 2+ Compound (CoCl 2 .6H 2 O), after the raw material is completely dissolved, heat to 100°C, slowly add 1g of NaOH raw material within 20min, fully react for 2 hours, stop heating and cool to 20°C, add 1.5g of NO 3 - (sodium nitrate) and 0.5g formic acid, stir for 10min, add SiO 2 0.4g of low-nano-scale acidic silica sol, stirred for 10 minutes, and added pure water to 1000ml, to obtain a high-corrosion-resistant trivalent chromium blue-white passivator.

[0028] When in use, use acid (nitric acid) or alkali (NaOH) to adjust the pH of the passivating agent solution to 2.3, and passivate the galvanized workpiece (galvanized layer thickness 6-10μm, barrel-plated screw) at 30°C, and the passivation time 50 seconds, after passivation is completed, 55 ℃ hot water is closed f...

Embodiment 3

[0032] Under continuous stirring, the Cr containing chromium 6g 3+ Compound (CrCl 3 .6H 2 O) Dissolve in 100ml pure water, add 8g malonic acid, 3g ammonium bifluoride and Cobalt containing 0.5g successively 2+ Compound (Co(NO 3 ) 2 .6H 2 O), after the raw material is completely dissolved, heat to 70°C, slowly add 2g NaOH raw material within 30min, fully react for 3 hours, stop heating and cool to 30°C, add NO 3 - The amount is 3g (including Co(NO 3 ) 2 .6H 2 NO in O 3 - and adding NaNO 3 The sum of the amount), add 1g of formic acid, stir for 20min, add SiO 2 2g of low-nano-scale acidic silica sol, stirred for 20 minutes, and added pure water to 1000ml, to obtain a high-corrosion-resistant trivalent chromium blue-white passivator.

[0033] When in use, use acid (nitric acid) or alkali (NaOH) to adjust the pH of the passivating agent solution to 1.3, and passivate the galvanized workpiece (galvanized layer thickness 6-10μm, barrel-plated screw) at 20°C, and the pa...

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Abstract

The invention relates to a high corrosion resistant trivalent chromium pearl opal passivating agent and a preparation method of the high corrosion resistant trivalent chromium pearl opal passivating agent. The invention belongs to the metal surface treatment technical field. The passivating agent comprises a Cr3+ chemical compound which contains 2 to 6 g/L chromium, 5 to 8 g/L malonic acid, a Co2+ chemical compound which contains 0.5 to 1 g/L cobalt, 1 to 3 g/L ammonium acid fluoride, 1 to 2 g/L sodium hydroxide, 1.5 to 3 g/L NO3-, 0.5 to 1 g/L formic acid, a low nanometer dimension acid silicasol which contains 0.4 to 2 g/L SiO2, and the rest being water. The preparation method of the passivating agent is that the Cr3+ chemical compound, the malonic acid, the ammonium acid fluoride, and the Co2+ chemical compound are heated up and reacted under 70 DEG C to 100 DEG C. When the temperature is from 20 DEGC to 30 DEGC, the NO3- is added. The formic acid and low nanometer dimension acid silicasol are added. Adding water to constant volume, the passivating agent is obtained. The passivating agent of the invention has the advantages that no hexavalent chrome is contained, and the production process has no hexavalent chrome pollution. When passivating, the passivating agent facilitates forming a uniform and dense passivation layer. And the corrosion resistance of the passivation layer is greatly promoted.

Description

technical field [0001] The invention relates to a high-corrosion-resistant trivalent chromium blue-white passivator and a preparation method thereof, belonging to the technical field of metal surface treatment. Background technique [0002] In order to improve the corrosion resistance of steel parts, zinc or its alloys (zinc-nickel, zinc-cobalt and zinc-iron) are usually coated on the surface of the parts to form a galvanized layer. In order to further improve its corrosion resistance and decorative properties, the coating must be carried out Passivation treatment to form a passivation film with high corrosion resistance and good decoration. In the past, people have used hexavalent chromium for passivation treatment. The passivation process of hexavalent chromium is mature and stable, with high corrosion resistance and self-healing ability to repair corrosion resistance. The source of raw materials is wide and cheap, but hexavalent chromium has It is highly toxic and carcin...

Claims

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Application Information

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IPC IPC(8): C23C22/48
CPCC23C2222/10C23C22/34
Inventor 周保学刘国琴张益平李金花李龙海蔡伟民
Owner 深圳市天泽科技实业有限公司
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