Zinc and zinc alloy plating black passivation solution and preparation method thereof

A technology of zinc alloy and passivation solution, which is applied in the coating process of metal materials, etc., can solve the problems of uneven passivation layer, easy peeling off, uneven black film, etc., achieve high market competitiveness, development potential, and easy operation Easy to learn, good corrosion resistance

Inactive Publication Date: 2011-04-13

济南德锡科技有限公司

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AI-Extracted Technical Summary

Problems solved by technology

However, after the passivation parts treated with trivalent chromium passivation solution are placed for a period of time, hexavalent chromium will appear in the passivation film, and as the storage time prolongs, hexavalent chromium will gradually increase, far exceeding the EU regulations RoHS Directive and the requirements of the WEEE Directive

This problem has become a problem that plagues the further promotion and application of trivalent chromium passivation technology, and has caused many companies to return products. It has become the most difficult problem in trivalent chromium passivation that needs to be solved urgently.

[0004] The trivalent chromium black passivation solution based on organic precursors described in patent CN101831648C is characterized in that the acid mordant dye is one or both of acid mordant black PV and acid mordant black T, forming a dye-chromium-dye Complex black lake, attached to the gel-like Cr(OH) 3 During the precipitation, a black passivation film is obtained, but the passivation film obtained from this is not well bonded, the black film is uneven, and it...

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Method used

Carry out black passivation after workpiece and test piece galvanizing according to the technique that embodiment one provides, carry out neutral salt spray test continuous spray 72 hour...

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Abstract

The invention discloses zinc and zinc alloy plating black passivation solution and preparation method thereof. The passivation solution consists of 5 to 50g/L of trivalent chromic salt, 1 to 10g/L of auxiliary film forming agent, 0.2 to 10g/L of reducing agent, 2 to 15g/L of pH buffer agent, 1 to 50g/L of chelating agent, 0.5 to 10g/L of blackening agent, 1 to 50g/L of oxidant and 0 to 50g/L of pH regulator. The passivation solution has stable working solution performance and low cost, and is simple and convenient to operate and easy to learn; zinc and zinc alloy plated parts passivated by the working solution are black and bright, uniform in color and good in corrosion resistance, reach level 8 in 72 hours, and have good bonding force; and the plating solution and coatings totally contain no Cr(VI), and the Cr(VI) cannot be detected from workpieces placed for a long term, so the passivation solution has high market competitiveness and development potential.

Application Domain

Metallic material coating processes

Technology Topic

Chromic saltCorrosion +4

Image

Examples

Experimental program(5)
Effect test(1)

Example Embodiment

[0046] Example 1 (1L as an example)

[0047] Chromium Nitrate 10g

[0048] Cobalt sulfate 2g

[0049] Silica sol 1g

[0050] Polyamide 1g

[0051] Anhydrous sodium sulfite 2g

[0052] Malonic acid 7g

[0053] Oxalic acid 7g

[0054] Sodium acetate 7g

[0055] Ferrous sulfate 3g

[0056] Manganese sulfate 3g

[0057] Nitric acid 5g

[0058] The rest is water

[0059] Preparation method:

[0060] 1) Weigh 10g of trivalent chromium salt into the container, add 50ml of deionized water, stir evenly,

[0061] 2) Heat to 75-80°C, add 7g malonic acid and 7g oxalic acid, stir until completely dissolved;

[0062] 3) Add 2g of cobalt sulfate, 1g of silica sol and 1g of polyamide, stir to completely dissolve and mix well;

[0063] 4) Reduce to room temperature, add 2g of anhydrous sodium sulfite and 7g of sodium acetate, dissolve and stir evenly to obtain component A for use;

[0064] 5) Take another container, add 50ml of deionized water, 3g ferrous sulfate, 3g manganese sulfate and 5g nitric acid successively, dissolve and stir evenly to obtain component B for later use;

[0065] 6) Add 500ml of deionized water to the container, add component A, stir evenly, then add component B, after complete mixing, constant volume, adjust the pH of the plating solution to 2.0 with nitric acid or sodium hydroxide, and the temperature to 50 -60℃, it can passivate galvanized and zinc alloy parts.

[0066] How to use: The workpiece or test piece is electroplated with zinc or zinc alloy for 25 minutes, and the thickness of the coating is about 8μm, then the plated piece is immersed in the prepared passivation solution, and the workpiece or test piece is shaken at a speed of 1 time/s, about 10-20s It's done.

Example Embodiment

[0067] Example 2

[0068] Basic chromium sulfate 12g

[0069] Cobalt sulfate 2g

[0070] Silane coupling agent A-171 1g

[0071] Potassium dihydrogen phosphate 2g

[0072] Sodium hypophosphite 3g

[0073] Succinic acid 7g

[0074] Glycine 10g

[0075] Acetic acid 3g

[0076] Nickel sulfate 5g

[0077] Silver nitrate 2g

[0078] Ammonium molybdate 7g

[0079] Sulfuric acid 5g

[0080] The rest is water

[0081] The preparation method and usage method are the same as in Example 1.

Example Embodiment

[0082] Example 3

[0083] Chromium Nitrate 15g

[0084] Cobalt sulfate 2g

[0085] Ethylenediamine tetramethylene phosphonic acid 2g

[0086] Polyvinyl chloride 1g

[0087] Thiourea 4g

[0088] Glycolic acid 13g

[0089] Malic acid 4g

[0090] Oxalic acid 3g

[0091] Boric acid 5g

[0092] Manganese sulfate 2g

[0093] Silver nitrate 5g

[0094] Sodium nitrate 10g

[0095] Nitric acid 5g

[0096] The rest is water

[0097] The preparation and use methods are the same as in Example 1.

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PUM

Property	Measurement	Unit
Thickness	8.0	µm
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Stable performance
Easy to operate and learn

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Low cost Uniform color Good corrosion resistance Good binding Reducing agent

Zinc and zinc alloy plating black passivation solution and preparation method thereof

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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