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Trivalent chromium blue and white passivator and method for making the same

A passivation agent, blue-white technology, applied in the direction of metal material coating process, etc., to achieve the effect of uniform appearance, strong decoration, and improved quality

Inactive Publication Date: 2008-02-27
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there is no such solution in the prior art

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] 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 pure water to 1000ml, and obtain trivalent chromium blue-white passivator.

[0036] 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 water is closed for 30 seconds, and dried at 80 ℃.

[0037] The passivated workpiece is measured according t...

Embodiment 2

[0041] 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 pure water to 1000ml, and obtain trivalent chromium blue-white passivator.

[0042] 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 for 40 seconds, and dried at 75 ℃.

[0043] The corrosion resistance of the passivated workpiece is tested by...

Embodiment 3

[0046] 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 pure water to 1000ml, and get the trivalent chromium blue-white passivator.

[0047] 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 passivation time 15 seconds, after the passivation is completed, the hot water at 65°C is closed for 20 seco...

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Abstract

The present invention relates to a chromic blue-white colour passivating agent and its preparation method. The raw material composition of said passivating agent includes 2-6g / l of chrome-containing Cr3+compound, 5-8g / l of propane diacid, 0.5-1g / l of cobalt-containing Co2+compound, 1-3g / l of ammonium bifluoride, 1-2g / l of NaOH, 1.5-3g / l of NO3-, 0.5-1g / l of formic acid and the rest is pure water. Besides, said invention also provides the concrete operation steps of its preparation method.

Description

technical field [0001] The invention relates to a trivalent chromium blue-white passivator and a preparation method thereof. The trivalent chromium blue-white passivator with high corrosion resistance and high decorative property is prepared, and belongs 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 been using hexavalent chromium for passivation treatment. The passivation process of hexavalent chromium is mature and stable, with high corrosion resistance and self-healing ability of self-repair and corrosion resista...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/48
CPCC23C2222/10C23C22/34
Inventor 周保学李龙海李金花刘国琴张益平
Owner SHANGHAI JIAO TONG UNIV
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