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Electrochemical method for preparing tin coating rear earth or molybdate passive film

An electrochemical and molybdate technology, applied in the coating process of metal materials, etc., can solve the problems of good passivation effect and achieve excellent corrosion resistance

Inactive Publication Date: 2014-09-24
SHENYANG LIGONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, inorganic passivation mainly includes: tungstate passivation, molybdate passivation, phosphate passivation, titanium salt passivation, zirconate passivation and rare earth passivation, etc. Both layers have a certain protective effect, but the effect is not as good as the passivation effect of chromate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0011] A preparation method for electrochemically preparing tin-plated layer rare earth / molybdate passivation film, comprising the following process steps:

[0012] Mix 25g / L sodium molybdate and 5g / L cerium nitrate, adjust the pH value of the mixed solution to 4.0-6.0 with citric acid, add 4g / L citric acid, 8g / L tartaric acid, and stir with a magnetic stirrer until it becomes blunt. Chemical solution, at a constant current of 0.6A / dm 2 At a temperature of 30°C, put the passivated sample after degreasing and derusting into the passivation solution for 10s to obtain it.

Embodiment 2

[0014] A preparation method for electrochemically preparing tin-plated layer rare earth / molybdate passivation film, comprising the following process steps:

[0015] Mix 25g / L sodium molybdate and 5g / L cerium nitrate, adjust the pH value of the mixed solution to 4.0-6.0 with citric acid, add 4g / L citric acid, 8g / L tartaric acid, and stir with a magnetic stirrer until it becomes blunt. Chemical solution, at a constant current of 0.2A / dm 2 At a temperature of 50°C, put the passivated sample after degreasing and derusting into the passivation solution for 3s to obtain the product.

Embodiment 3

[0017] A preparation method for electrochemically preparing tin-plated layer rare earth / molybdate passivation film, comprising the following process steps:

[0018] Mix 25g / L sodium molybdate and 5g / L cerium nitrate, adjust the pH value of the mixed solution to 4.0-6.0 with citric acid, add 4g / L citric acid, 8g / L tartaric acid, and stir with a magnetic stirrer until it becomes blunt. Chemical solution, at a constant current of 0.4A / dm 2 , at a temperature of 40°C, put the passivated sample after degreasing and derusting into the passivation solution for 6s to obtain the product.

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PUM

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Abstract

The invention relates to an electrochemical method for preparing tin coating rear earth or a molybdate passive film. The electrochemical method comprises the steps of mixing 25g / L of sodium molybdate with 5g / L of cerous nitrate, adjusting the pH value of the mixed solution to be 4.0-6.0 with citric acid, adding 4g / L of citric acid and 8g / L of tartaric acid, stirring by a magnetic stirrer, wherein the constant current is 0.2-0.6A / dm<2> and the temperature is 30-50DEG C, putting the passivated sample with oil and rust removed into a passive liquor for passivating for 3-10 seconds, so as to obtain the product. The electrochemical method has the advantages that the sodium molybdate and cerous nitrate are mixed to be used as a base liquid, then additives are added, the magnetic stirrer is used for stirring, the tin coating passive film is obtained through electrochemical passivation, and the passive film has the characteristics of uniformity, compactness, and good corrosion resistance.

Description

technical field [0001] The invention belongs to the technical field of surface treatment, and relates to a preparation method of a rare earth / molybdate passivation film on a tin plating layer. Background technique [0002] As one of the key varieties developed by my country's metallurgical industry, tinplate is widely used in food and canning and printing iron industries. With the improvement of people's living standards, the demand for tinplate is also increasing. In the production process of tinplate, after the strip steel is tinned and reflowed, in order to improve the corrosion resistance of the tinplate layer and prevent the tin layer from oxidizing and yellowing during storage or baking, the tinplate must be treated. passivation treatment. At present, chromate is mainly used for passivation of tin plate. Since hexavalent chromium in chromate is extremely harmful to humans and the environment, it is imperative to replace hexavalent chromium passivation treatment. ...

Claims

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Application Information

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IPC IPC(8): C23C22/40
Inventor 郝建军郭雪
Owner SHENYANG LIGONG UNIV
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