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Environmentally-friendly black chrome-silver-free zinc-plating passivation solution and preparation method thereof

An environment-friendly, passivating solution technology, applied in the direction of metal material coating process, can solve the problems of galvanizing enterprises that have a great impact on economic benefits and high production costs, and achieve improved clean production, improved corrosion resistance, and film formation high efficiency effect

Inactive Publication Date: 2010-11-03
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the research on chromium-free passivation solution for zinc coating at home and abroad mainly includes molybdate system, titanium salt system, rare earth system, silicate system, phytic acid system and organic system, etc., but these chromium-free passivation systems only It can form a (blue) white or colored passivation film on the surface of the galvanized layer. For the black passivated galvanized parts that are widely used in production, they still completely rely on hexavalent chromium or trivalent chromium passivation process.
[0006] In addition, in many black passivation processes of galvanized parts, in addition to using chromium salt as the main film-forming substance, it is usually necessary to add silver salt to the passivation solution as a blackening agent. The production cost has a great impact on the economic benefits of galvanizing enterprises

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] 1) Prepare materials according to the following formula: sodium silicate 10g / L, copper sulfate 20g / L, nickel sulfate 0.5g / L, ferrous sulfate 0.5g / L, sodium acetate 1g / L, glacial acetic acid 20mL / L, sulfuric acid (98 %) 3mL / L, the rest is water, and the raw materials used are commercially available chemically pure products, H 2 O is tap water;

[0037] 2) The silicate black passivation solution is prepared by the following method for subsequent use:

[0038] A, 10g of sodium silicate is dissolved in a small amount of water to obtain a completely dissolved aqueous solution of sodium silicate;

[0039] B, 3mL sulfuric acid (98%) is added in the sodium silicate aqueous solution of A step, mixes evenly;

[0040] C, 20g copper sulfate is added in the mixed solution of B step, mixes evenly;

[0041] D, 0.5g nickel sulfate is added in the mixed solution of C step, mixes evenly;

[0042] E, 0.5g ferrous sulfate is added in the mixed liquor of D step, mixes evenly;

[0043] ...

Embodiment 2

[0051] 1) Prepare materials according to the following formula: sodium silicate 15g / L, copper sulfate 25g / L, nickel sulfate 1.0g / L, ferrous sulfate 1.0g / L, sodium acetate 2g / L, glacial acetic acid 30mL / L, sulfuric acid (98 %) 5mL / L, the rest is water, and the raw materials used are commercially available chemically pure products, H 2 O is distilled water.

[0052] 2) through the method identical with embodiment 1, be mixed with the silicate black passivation solution that pH value is about 2.2, for subsequent use:

[0053] 3) The electro-galvanized steel plate is obtained by the following method: the Q235 steel plate of 100 mm × 60 mm × 2 mm is subjected to pre-treatments such as rust removal, degreasing, activation, etc. The bath composition and operating conditions of the treatment process are: ZnO: 10g / L, NaOH: 120g / L, Z50 alkaline galvanizing additive 8mL / L, the pH of the bath is 12, and the current density is 2.0A / dm 2 , the temperature is room temperature, and the elec...

Embodiment 3

[0058] 1) Prepare materials according to the following formula: sodium silicate 20g / L, copper sulfate 30g / L, nickel sulfate 1.5g / L, ferrous sulfate 1.5g / L, sodium acetate 3g / L, glacial acetic acid 40mL / L, sulfuric acid (98 %) 7mL / L, the rest is water, and the raw materials used are commercially available chemically pure products, H 2 O is tap water.

[0059] 2) Prepare a silicate color passivation solution with a pH value of about 2.5 through the same method as in Example 1, for subsequent use;

[0060] 3) Alkaline electro-galvanizing treatment of a steel shell of a certain machine: Electroplating is carried out after the steel shell of a certain machine is subjected to conventional derusting, degreasing, weak etching, pre-soaking, etc., and the composition of the plating solution of the galvanizing process and The operating conditions are: ZnO 10g / L, NaOH 120g / L, Z50 alkaline galvanizing additive 8mL / L, current density 2.5A / dm 2 , The temperature is room temperature, the el...

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Abstract

The invention provides black passivation solution for zinc-plating post treatment. 1 liter of black passivation solution consists of 10 to 20g of sodium silicate, 20 to 30g of copper sulfate, 0.5 to 1.5g of nickel sulfate, 0.5 to 1.5g of ferrous sulfate, 1 to 3g of sodium acetate, 20 to 40mL of glacial acetic acid, 3 to 7mL of sulfuric acid (98 percent) and the balance of water. A zinc-plating material processed by the passivation solution has a uniform, bright and black appearance and high corrosion resistance, is free of rust for over 200h through a neutral salt spray test and can achieve the same effect as that achieved by the conventional black chrome-silver-contained passivation process in appearance and performance. The passivation solution has the advantages of thoroughly solving the problem of environment pollution caused by a chromium salt used by the conventional black zinc-plating passivation process, eliminating the use of a silver salt at the same time and greatly reducing the cost thereof by substituting silicate for the chromium salt as a main film-forming material and a copper salt, a nickel salt and a ferric salt for the silver salt as a blackening agent, along with stability and reliability and high film-forming efficiency.

Description

technical field [0001] The invention relates to the technical field of material surface treatment, in particular to a chromium-free and silver-free environment-friendly galvanized black passivation solution used as a post-treatment solution for electrogalvanized iron and steel parts and a preparation method thereof. Background technique [0002] Material corrosion and material anticorrosion engineering are directly related to economic development and people's life safety. Surface engineering technology is the most economical and effective means and method to solve the corrosion and protection of mechanical parts and materials. [0003] Electrogalvanizing is an effective way to improve the corrosion resistance of the surface of steel materials, and is currently widely used in many fields such as construction, transportation, machinery, electronics, and aviation. However, in a humid environment, especially in a hot and humid environment, the galvanized layer is prone to corros...

Claims

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Application Information

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IPC IPC(8): C23C22/53
Inventor 范云鹰
Owner KUNMING UNIV OF SCI & TECH
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