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Method of prolonging service life of galvanized trivalent chromium passivating solution

A passivation solution, trivalent chromium technology, applied in the direction of metal material coating process, etc., can solve the problems of short life of trivalent chromium passivation solution, burden of sewage treatment, inability to achieve clean production, energy saving and emission reduction, etc. The effect of prolonging the life, reducing the discharge of waste liquid, and prolonging the service life

Active Publication Date: 2012-07-11
宏正(福建)化学品有限公司
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  • Summary
  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

[0002] In the electroplating process, the hexavalent chromium passivation process is explicitly eliminated internationally, and the trivalent chromium passivation process is generally used, but the traditional trivalent chromium passivation solution has a short service life, and generally dies when the zinc ion content reaches about 5g / L Unable to obtain a qualified passivation film, the passivation solution must be exchanged or even poured out, which brings a large burden to sewage treatment and cannot achieve clean production, energy saving and emission reduction

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0009] EKEM-261 trivalent chromium blue and white new passivation solution preparation, 50ml / L (Cr 3+ Content 1.1g / L), adjust the pH value to 1.8. After the steel is galvanized, enter the new passivation solution for passivation for 10 seconds. As a result, the appearance of the plated parts is uniform blue, and the resistance to neutral salt spray test (NSS) is 72-96 hours. Keep Cr in the passivation solution 3+ The content remains unchanged (1.1g / L), the pH value is 1.8, after 15 days of work, the Zn in the passivation solution 2+ The concentration naturally rises to 5g / L. After the steel is galvanized, it is passivated in the old passivation solution for 10 seconds. As a result, the corners, holes, etc. are yellow and uneven in color, and the NSS resistance is reduced to 48-72 hours. Add 0.5g / L ethylenediaminetetraacetic acid (EDTA) to the old passivation solution, and adjust the pH to 2.3 for regeneration. After the steel is galvanized, enter the regeneration passivation...

Embodiment 2

[0011] Replace 0.5g / L of EDTA in Example 1 with 0.5g / L of nitrogen triacetic acid (NTA), and adjust the pH value to 2.3 for regeneration. After the steel is galvanized, enter the regeneration passivation solution for passivation for 10 seconds. The appearance of the film is blue and uniform, and it can withstand NSS for 72-96 hours, returning to the level of opening the tank.

Embodiment 3

[0013] After the EKEM-261 trivalent chromium blue-white regenerated passivation solution of Example 1 worked for 20 days (35 days in total), the Cr in the passivation solution continued to be maintained. 3+ The content remains unchanged (1.1g / L), Zn in the passivation solution 2+ The concentration naturally rises to 8g / L. Add 0.2g / L of EDTA to the passivation solution (0.7g / L accumulatively), and adjust the pH to 2.5. The appearance of the passivation film is uniform blue, and it can withstand NSS for 72-96 hours, returning to the level of opening the tank. The life of the passivation solution is more than doubled.

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Abstract

The invention relates to a method of prolonging the service life of a galvanized trivalent chromium passivating solution. The method is characterized in that an amino carboxylic acid complexing agent is added into a galvanized trivalent chromium old passivating solution, and the pH value of the galvanized trivalent chromium old passivating solution is increased via adjustment. The amino carboxylic acid complexing agent is ethylene diamine tetraacetic acid (EDTA) or nitrilotriacetic acid (NTA) for best selection, and exhibits an amount ranging from 0.2-5g / L, with optimum amount being 0.5 to 2g / L. The pH value depends on the concentration of zinc ions in the galvanized trivalent chromium old passivating solution, and as compared with a new passivating solution, the pH value is increased by 0.05-0.1 each time when zinc ions are increased by 1g / L. The method of the invention enables the usage time of the passivating solution to be prolonged, and various properties of a passive film obtained by a workpiece are equivalent to those of a new cylinder. The service life of the passivating solution is prolonged, thereby minimizing waste liquid and realizing an effect of environment protection.

Description

technical field [0001] The invention relates to a method for prolonging the service life of a galvanized trivalent chromium passivation solution. Background technique [0002] In the electroplating process, the hexavalent chromium passivation process is explicitly eliminated internationally, and the trivalent chromium passivation process is generally used, but the traditional trivalent chromium passivation solution has a short service life, and generally dies when the zinc ion content reaches about 5g / L If a qualified passivation film cannot be obtained, the passivation solution must be exchanged or even poured out, which will bring a greater burden to sewage treatment and fail to achieve clean production, energy saving and emission reduction. Contents of the invention [0003] The purpose of the present invention is to provide a method for prolonging the service life of the galvanized trivalent chromium passivation solution, and use it to treat the aging passivati...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/53C23C22/06C23C22/34C25D5/48
Inventor 叶金堆
Owner 宏正(福建)化学品有限公司
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