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Chromium-free passivator for shot blasting components for die-cast aluminum, method for preparing chromium-free passivator and method for applying same

A chromium-free passivation agent and cast aluminum technology, applied in the direction of metal material coating technology, can solve the problems of poor durability, weak bonding ability, poor bonding and other problems, achieve simple production process, good film-forming effect, Strong corrosion resistance effect

Active Publication Date: 2015-09-09
重庆德蒙特科技发展有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the corrosion resistance of inorganic passivation technology or organic passivation technology cannot reach the effect of chromium passivation.
Moreover, the film-forming effect of the existing chromium-free passivation technology is unstable, and there are problems such as poor bonding with other coatings and weak bonding ability, poor durability, and easy foaming and falling off

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] The die-cast aluminum shot blasting part of the present embodiment has a chromium-free passivator, and the raw material of the chromium-free passivator includes the following components by weight: 1.6% ammonium fluorozirconate, 0.15% ammonium metavanadate, 0.68% citric acid, Magnesium nitrate 1%, cobalt sulfate heptahydrate 1.5%, ammonia 0.14%, water 94.93%.

[0016] Heat water to boiling, add ammonium fluozirconate and ammonium metavanadate, cool to room temperature, then add citric acid and stir until clarified, finally add magnesium nitrate and cobalt sulfate heptahydrate, add ammonia water to adjust the pH value of the solution to 2.5, and obtain Passivating agent stock solution.

[0017] Add water to the passivating agent at 5% by volume to prepare a working solution, the pH value of the working solution is 4.5, the use temperature is 23° C., and the passivation time is 6 minutes.

Embodiment 2

[0019] Chromium-free passivating agent for die-casting aluminum shot blasting parts, the raw materials of said chromium-free passivating agent include the following components by mass percentage:

[0020] 0.5% ammonium fluozirconate, 0.05% ammonium metavanadate, 0.01% citric acid, 0.1% magnesium nitrate, 0.5% cobalt sulfate heptahydrate, 0.05% ammonia water, and the balance is water to 100%.

[0021] Heat the water to boiling, add ammonium fluozirconate and ammonium metavanadate, cool to room temperature, then add citric acid and stir until clarification, finally add magnesium nitrate and cobalt sulfate heptahydrate, add ammonia water to adjust the pH value of the solution to 3, and obtain Passivating agent stock solution.

[0022] Add water to the passivating agent at 2% by volume to prepare a working solution, the pH of the working solution is 4, the use temperature is 20° C., and the passivation time is 3 minutes.

Embodiment 3

[0024] Chromium-free passivating agent for die-casting aluminum shot blasting parts, the raw materials of said chromium-free passivating agent include the following components by mass percentage:

[0025] 5% ammonium fluozirconate, 0.5% ammonium metavanadate, 1% citric acid, 5% magnesium nitrate, 3% cobalt sulfate heptahydrate, 0.5% ammonia water, and the balance is water to 100%.

[0026] Heat water to boiling, add ammonium fluozirconate and ammonium metavanadate, cool to room temperature, then add citric acid and stir until clarified, finally add magnesium nitrate and cobalt sulfate heptahydrate, add ammonia water to adjust the pH value of the solution to 2.5, and obtain Passivating agent stock solution.

[0027] Add water to the passivating agent at 8% by volume to prepare a working solution, the pH value of the working solution is 5, the use temperature is 25° C., and the passivation time is 10 minutes.

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PUM

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Abstract

The invention discloses a chromium-free passivator for shot blasting components for die-cast aluminum, a method for preparing the chromium-free passivator and a method for applying the same. The chromium-free passivator comprises 0.5-5% of ammonium zirconium hexafluoride, 0.05-0.5% of ammonium metavandate, 0.01-1% of citric acid, 0.1-5% of magnesium nitrate, 0.5-3% of cobalt monosulfate heptahydrate, 0.05-0.5% of ammonia water and the balance water. The chromium-free passivator and the methods have the advantages that a stable passivation film can be formed on the surface of each shot blasting component for the die-cast aluminum, is firm, dense and stable and is high in corrosion resistance and free of sediments, excellent film forming effects can be realized, passivated workpieces appear natural metal colors after shot blasting is carried out, and corroded areas are not larger than 10% of the total areas of the workpieces as shown by 24h bare neutral salt spray tests; high binding force can be generated between the chromium-free passivator and different types of coat, and the chromium-free passivator passes impact tests and cross tests; coatings are free of bubbling and falling in the neutral salt spray tests after being coated for 500h; the chromium-free passivator is free of trivalent chromium or hexavalent chromium or other heavy metal elements, is nontoxic, pollution-free, non-flammable and non-explosive and is excellent in environmental friendliness.

Description

technical field [0001] The invention relates to the technical field of metal surface treatment, in particular to a chromium-free passivator for die-casting aluminum shot blasting parts that is passivated, a preparation method and a use method thereof. Background technique [0002] The technology of passivating aluminum alloys to improve their anti-corrosion properties has a history of hundreds of years. The traditional passivation technology uses hexavalent chromium as its main film-forming substance. The obtained passivation film can meet the needs of industrial production. However, after the seriousness of hexavalent chromium to environmental pollution was fully recognized by people, hexavalent chromium was listed as a strictly prohibited substance. Instead, a trivalent chromium passivator with trivalent chromium as the main film-forming substance appeared. The obtained passivation film can also basically meet the needs of industrial production. Although the pollution ...

Claims

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Application Information

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IPC IPC(8): C23C22/44
Inventor 何洪胤
Owner 重庆德蒙特科技发展有限公司
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