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A trivalent chromium blue-white passivation solution for treating die-casting zinc alloys

A technology of trivalent chromium and passivation solution, applied in the direction of metal material coating process, etc., to achieve the effect of simple wastewater treatment, white and bright color, and simple production equipment

Inactive Publication Date: 2016-03-16
SOUTHWEST UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the currently commonly used die-casting zinc alloy trivalent chromium passivation solution is either expensive or not resistant to neutral salt spray corrosion for a long time.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] All passivation solutions are prepared from commercially available industrial pure grade raw materials. Weigh Cr 2 (SO 4 ) 3 ·6H 2 O3g, K 2 ZrF 6 0.5g, KAl(SO 4 ) 2 12H 2 0.1g, mixed additive 0.5g; Under normal temperature and pressure, trivalent chromium salt is dissolved in appropriate amount of water, while stirring, add zirconium salt and KAl(SO 4 ) 2 12H 2 O, continue stirring to dissolve completely; then add mixed additives, stir evenly; finally add water to 10L.

[0019] The operating process is:

[0020] (1) Degreasing: Dip the die-cast zinc alloy into the degreasing agent to remove the oil stains on the surface;

[0021] (2) Cleaning: Wash the degreasing agent on the surface of the zinc alloy with clean water, and wash twice;

[0022] (3) Passivation: Dip the cleaned die-cast zinc alloy into the prepared trivalent chromium passivation solution, adjust the working pH of the passivation solution to 3.3, the working temperature to 33°C, and the passiv...

Embodiment 2

[0028] All passivation solutions are prepared from commercially available industrial pure grade raw materials. Weigh the trivalent chromium salt Cr 2 (SO 4 ) 3 ·6H 2 O4g, K 2 ZrF 6 1g, KAl(SO 4 ) 2 12H 2 O0.5g, mixed additive 1g.

[0029] The preparation method and operation process are the same as in Example 1, and 10L of passivation working solution is prepared. Adjust the working pH of the passivation solution to 3.7, the working temperature to 37°C, and the passivation time to 25 minutes.

[0030] The zinc alloy workpiece processed by the above method has a white and bright passivation film on the surface, which is blue-white; the neutral salt spray corrosion test can reach 132 hours, and the corrosion area is less than 5% (the neutral salt spray corrosion test adopts GB / The method stipulated in T10125-2012 "Artificial Atmosphere Corrosion Test Salt Spray Test").

Embodiment 3

[0032] All passivation solutions are prepared from commercially available industrial pure grade raw materials. Weigh the trivalent chromium salt CrCl 3 ·6H 2 O3g, ZrOCl 2 ·8H 2 O0.5g, KAl(SO 4 ) 2 12H 2 O0.1g, mixed additives 0.5g.

[0033] The preparation method and operation process are the same as in Example 1, and 10L of passivation working solution is prepared. Adjust the working pH of the passivation solution to 3.3, the working temperature to 33°C, and the passivation time to 15 minutes.

[0034] The zinc alloy workpiece processed by the above method has a white and bright passivation film on the surface, which is blue-white; the neutral salt spray corrosion test can reach 96 hours, and the corrosion area is less than 5% (the neutral salt spray corrosion test adopts GB / The method stipulated in T10125-2012 "Artificial Atmosphere Corrosion Test Salt Spray Test").

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PUM

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Abstract

A trivalent chromium blue-white passivation solution for treating die-casting zinc alloys, its components and contents are: trivalent chromium salt? 0.3~0.4? g / L, zirconium salt? 0.05~0.1? g / L, KAl(SO4)2·12H2O? ? 0.01~0.05? g / L, mixed additives? 0.05~0.1? g / L, the balance is water; in the trivalent chromium passivation solution, the contents of hexavalent chromium, lead, cadmium, mercury, polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) all meet the requirements of EU ROHS limit standards; The production equipment is simple and the cost is low; after being treated with the trivalent chromium passivation solution, the surface color of the die-cast zinc alloy is white and bright, slightly blue-white; the neutral salt spray corrosion resistance time of the passivation film layer can reach more than 96 hours. The trivalent chromium passivation solution for die-casting zinc alloy can replace the traditional zinc alloy hexavalent chromium passivation solution.

Description

technical field [0001] The invention belongs to the technical field of metal surface treatment and anticorrosion, and in particular relates to a trivalent chromium blue-white passivation solution for treating die-casting zinc alloys. technical background [0002] The content of zinc in the earth's crust is 0.013%, and it is an important metal raw material. Its output and consumption rank fourth after iron, aluminum and copper. Zinc alloys are widely used due to their many advantages, such as low melting point, good fluidity, easy fusion welding, brazing and plastic processing. However, the passivity coefficient of zinc is low, only 0.024. Therefore, in the natural state, the oxide film formed automatically by zinc alloy is loose, thin and uneven, which makes it difficult for the metal under the naturally formed oxide film to resist the harm of common corrosion. Seriously affect the performance of the product. Therefore, in order to improve the surface quality of zinc allo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C22/40C23C22/44
Inventor 石燕汪晓琴张梓梁张俊豪
Owner SOUTHWEST UNIV
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