Method for passivation of zinc and zinc alloy and chromium-free passivation solution

A chromium-free passivation and passivation solution technology, applied in the coating process of metal materials, etc., can solve the problems of ecological environmental hazards, poor corrosion resistance, high cost, etc., and achieve the effects of reducing costs, saving costs, and avoiding harm

Inactive Publication Date: 2012-08-15
东莞市闻誉实业有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The chromate passivation process makes the zinc coating passivate through chromate to form a mixed oxide film of chromium and zinc. The chromium ions in the film are mainly Cr 3+ and Cr 6+ exists in the form of Cr 3+ The oxide serves as the skeleton, although the Cr 6+ The oxide has strong oxidizing property and self-healing effect, but it is difficult to treat the waste liquid after chromating with chromate, and the Cr contained in the waste liquid 6+ Ions are highly toxic and have great harm to the human body and the ecological environment
Trivalent chromium passivation is a low-toxicity alternative to chromate passivation. However, the passivated parts treated with trivalent chromium passivation solution, after about 1 week of placement, will not passivate in trivalent chromium passivation. The presence of hexavalent chromium will be detected in the chemical film, which limits the application of this process
[0006] Although the existing zinc and zinc alloy passivators have made great progress in avoiding environmental pollution, most of them have insufficient corrosion resistance and high cost

Method used

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  • Method for passivation of zinc and zinc alloy and chromium-free passivation solution
  • Method for passivation of zinc and zinc alloy and chromium-free passivation solution
  • Method for passivation of zinc and zinc alloy and chromium-free passivation solution

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] A solution consisting of the following was stirred and adjusted to pH 2 with 10% sodium hydroxide:

[0042]

[0043] Immerse the steel plate coated with 8 micron zinc in the above-mentioned chromium-free passivation solution for 5s, then let it stand in the air for 10s, then immerse it in the chromium-free passivation solution for 5s, then rinse and dry it; finally put the workpiece at 40℃ The passivation is completed after drying for 10 minutes, forming a uniform clear to blue conversion coating.

Embodiment 2

[0045] A solution consisting of the following was stirred and the pH was adjusted to 4.3 with 10% sodium hydroxide:

[0046]

[0047] Immerse the steel plate coated with 8 micron zinc in the above-mentioned chromium-free passivation solution for 5s, then let it stand in the air for 5s, then immerse it in the chromium-free passivation solution for 20s, then rinse and dry it; finally put the workpiece at 70℃ After drying for 15 minutes, the passivation is completed, and the resulting steel plate has a shiny pink / blue surface layer.

Embodiment 3

[0049] A solution consisting of the following was stirred and adjusted to pH 3 with 10% sodium hydroxide:

[0050]

[0051] Immerse the steel plate coated with 8 micron zinc in the above-mentioned chromium-free passivation solution for 20s, then let it stand in the air for 10s, then immerse it in the chromium-free passivation solution for 1min, then rinse and dry it; finally put the workpiece at 80℃ The passivation was completed after drying for 13 minutes, forming a uniform clear to blue conversion coating.

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Abstract

The invention relates to a method for passivation of zinc and zinc alloy and a chromium-free passivation solution. The passivation method comprises the following steps: soaking a workpiece electroplated with a zinc or zinc alloy layer into a chrome-free passivation solution and then standing in the air; re-soaking the workpiece into the chrome-free passivation solution, and then rinsing and blow-drying; finally drying the workpiece to complete passivation. The chromium-free passivation solution comprises the following components: a titanium salt, an oxidant, a complexing agent, a water-soluble film-forming agent, an accelerator, a Group II metal compound and water. The invention provides a chrome-free passivation solution that can generates blue or flash coating on the deposits of zinc and zinc alloy. The coating is uniform with excellent corrosion resistance, and can delay the appearance of white corrosion products. The passivation method provided by the invention is low in cost, easy in waste liquid treatment, and easy in operation and maintenance.

Description

technical field [0001] The invention belongs to the technical field of surface treatment, and in particular relates to a zinc and zinc alloy passivation method and a chromium-free passivation solution. Background technique [0002] Zinc and zinc alloys are easily corroded in hot and humid environments, and white spots and gray matter are formed on the surface. In order to improve the corrosion resistance and decorative properties of the galvanized layer, passivation treatment is required. Chromization of zinc deposits is a common method of delaying the appearance of white corrosion products. The chromate passivation process makes the zinc coating passivate through chromate to form a mixed oxide film of chromium and zinc. The chromium ions in the film are mainly Cr 3+ and Cr 6+ exists in the form of Cr 3+ The oxide serves as the skeleton, although the Cr 6+ The oxide has strong oxidizing property and self-healing effect, but it is difficult to treat the waste liquid afte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/53C23C22/06C23C22/34
Inventor 叶伟炳
Owner 东莞市闻誉实业有限公司
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