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Passivation method for brass antitarnish

An anti-discoloration, brass technology, applied in the direction of metal material coating process, etc., can solve the problems of elimination, anti-discoloration time is not durable enough, can not meet the requirements of decorative appearance, etc.

Active Publication Date: 2012-07-04
NINGBO LUO PIANOS COMPANY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The traditional brass passivation treatment mostly adopts chromic acid or chromate passivation, which is gradually eliminated due to serious pollution.
Most of the existing brass passivation treatments use organic corrosion inhibitors such as benzotriazole. Although they have achieved some results, they often cannot meet the anti-discoloration requirements under different conditions of acidity, alkalinity, and neutrality, and the anti-discoloration time is also limited. Not durable enough to meet the aesthetic requirements of some high-end products

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0036] 1. Test material: H62 brass, 20mm×40mm×2min.

[0037] 2. Method flow: sanding - alcohol scrubbing degreasing - water washing - room temperature cleaning agent degreasing - hot water washing - cold water washing - acid washing to light, activation - hot water washing - cold water washing - passivation - washing with deionized water - drying - Bake at 60 degrees Celsius for 30 minutes.

[0038] 3. Acid washing, light emission and activation: sulfuric acid 400-450ml / l, nitric acid 40-50ml / l, hydrochloric acid 5-7ml / l, gelatin 0.5-1g / l, polyethylene glycol 1-2g / l, OP emulsifier 10 -20ml / l. 25-35 degrees Celsius, 15-30s.

[0039] 4. Passivation method of the present invention: benzotriazole (BTA) 6g / l, 1-phenyl-5 mercaptotetrazolium (PMT) 2g / l, sodium molybdate 3g / l, citric acid 14g / l, Sodium lauryl sulfate 1g / l. The pH value of the solution is 2-3, the temperature is 55 degrees, and soaked for 3 minutes.

example 2

[0041] 1. Test material: same as Example 1

[0042] 2. Method flow: Same as Example 1

[0043] 3. Pickling, luminescence and activation: Same as Example 1

[0044] 4. Passivation method of the present invention: benzotriazole (BTA) 8g / l, 1-phenyl-5 mercaptotetrazolium (PMT) 2g / l, sodium tungstate 3g / l, citric acid 14g / l, Sodium lauryl sulfate 1g / l. The pH value of the solution is 2.5, the temperature is 60 degrees Celsius, and soaked for 3 minutes.

example 3

[0046] 1. Materials: Same as Example 1

[0047] 2. Method flow: Same as Example 1

[0048] 3. Pickling, luminescence and activation: Same as Example 1

[0049] 4. Common passivation methods (for comparison): benzotriazole (BTA) 8g / l, ethanol 40ml / l sodium lauryl sulfate 0.5g / l. The pH value of the solution is 4.5, the temperature is 50 degrees Celsius, and soaked for 3 minutes.

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PUM

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Abstract

The invention provides a passivation method for brass antitamish, which comprises the steps: a new passivating solution is adopted, which comprises 5-8g / l of benzotriazol (BTA), 2-4g / l of 1- phenyl- mercapto-tetrazole (PMT), 14-18g / l of tartaric acid (or citric acid), 2-4g / l of sodium molybdate (or sodium tungstate), and 0.5-1g / l of sodium dodecyl sulfate. When the solution is used for passivation, the pH value of the solution is 2-3, and the temperature is 50-60 DEG C, and the time is 3-5 min. The passivation effect can be achieved by putting the brass in the solution for passivation. The passivation method is simple in operation, fast, convenient, and environmental friendly; the brass antitarnish time in salt, acids, alkaline solutions media is durable.

Description

technical field [0001] The invention relates to a brass anti-discoloration passivation method, which belongs to the technical field of surface anti-corrosion. Background technique [0002] Brass alloys are easily corroded and lose their decorative color in an atmosphere containing water vapor, carbon dioxide and sulfides. Therefore, it is often necessary to apply an anti-tarnish treatment to it. Passivation treatment is a common anti-tarnish technology for brass. [0003] The traditional brass passivation treatment mostly uses chromic acid or chromate passivation, which is gradually eliminated due to its serious pollution. Most of the existing brass passivation treatments use organic corrosion inhibitors such as benzotriazole. Although they have achieved some results, they often cannot meet the anti-discoloration requirements under different conditions of acidity, alkalinity, and neutrality, and the anti-discoloration time is also limited. Not durable enough to meet the a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C22/40C23G1/10
Inventor 李炳生罗锐育邬立平
Owner NINGBO LUO PIANOS COMPANY
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