Non-chromium passivation technology for zinc coating

A chromium-free passivation and galvanized layer technology, applied in the coating process of metal materials, etc., can solve the problems of restricting the use and discharge of chromate, human and environmental hazards, toxicity, etc., and achieve good decorative effects and low environmental pollution , Bright and even color effect

Inactive Publication Date: 2014-12-24
朱忠良
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, because hexavalent chromium is carcinogenic, toxic, and harmful to humans and the environment, the government has strictly restricted the use and discharge of chromate

Method used

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  • Non-chromium passivation technology for zinc coating
  • Non-chromium passivation technology for zinc coating
  • Non-chromium passivation technology for zinc coating

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Embodiment 1 Influence of each component content on the quality of passivation film in the chromium-free passivation solution of galvanized layer of the present invention

[0026] (1) Effect of ammonium molybdate content on the quality of passivation film

[0027] Ammonium molybdate is the main salt of the passivation solution and provides the main component of the passivation film. Its dosage has a great influence on the molybdate process, as shown in Table 1.

[0028] Table 1, the effect of ammonium molybdate content on the quality of passivation film

[0029]

[0030] It can be seen from Table 1 that the content of ammonium molybdate should be controlled at 10-20g / L; if the content is too low, the passivation film will be thin and light in color, and it will be difficult or impossible to form a film; Uniform, poor decoration, there are microscopic cracks on the surface of the film layer, and the corrosion resistance is reduced.

[0031] (2) Effect of sodium pho...

Embodiment 2

[0040] The influence of embodiment 2 passivation conditions on passivation film quality

[0041] (1) Influence of the pH value of the passivation solution on the quality of the passivation film

[0042] The pH value of the passivation solution has a great influence on the film formation and corrosion resistance of the passivation film, as shown in Table 3.

[0043] Table 3. Influence of passivation solution pH on passivation film quality

[0044]

[0045] It can be seen from Table 3 that the pH value of the process should be controlled at 3-4.5. The formation process of the passivation film is accompanied by the dissolution of the metal, and the metal ions react with the passivating agent in the passivation solution to form a passivation film. Therefore, the zinc in the passivation solution should be in the region where the E-pH diagram corrodes moderately and produces zinc ions. According to the E-pH diagram of zinc in aqueous solution, zinc is in this region in the pas...

Embodiment 3

[0053] Embodiment 3 The performance detection of passivation film made by passivation solution and passivation process of the present invention

[0054] (1) The routine performance test results of the passivation film are shown in Table 5.

[0055] Table 5. Test results of routine performance of passivation film

[0056]

[0057] (2) Polarization curve of passivation film

[0058] The cathode electrochemical behavior of passivation film, non-passivation and chromate passivation film in 5% sodium chloride solution of this process was measured by galvanostatic method. The reference electrode is a saturated calomel electrode, and the auxiliary electrode is 1 cm 2 Platinum electrode, the sample is the research electrode (the exposed area is 1cm 2 ), the natural corrosion potential of the research electrode was measured first, and after 10 min the natural corrosion potential was stabilized, and the constant current polarization measurement was started. Adjust the current to a ...

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Abstract

The invention discloses a non-chromium passivation solution for a zinc coating and a non-chromium passivation technology using the non-chromium passivation solution. The passivation solution comprises ammonium molybdate, sodium phosphate and additives XZ-03B and OP-10. The composite passivation technology comprises the step that the passivation solution is subjected to passivation treatment for 1-2 min at the temperature of 20-60 DEG C, preferably 30-55 DEG C, more preferably 40-50 DEG C, and the preferable treatment time is 60-90 s. A non-chromium passive film prepared by adopting the non-chromium passivation solution for the zinc coating and the passivation technology is iridescent, the color is bright and uniform, the decorative effect is good, and the color is close to that of a chromate passivated film; and the performance of the passive film is close to that of the chromate passivated film, the corrosion resistance is excellent, the passivation solution does not contain hexavalent chromium, so that environment pollution is little, and the technology is environmental-friendly.

Description

technical field [0001] The invention relates to the technical field of galvanized layer passivation technology, in particular to a chromium-free passivated process for galvanized layer. Background technique [0002] Galvanized steel sheets are widely used in automobiles, building materials, home appliances, containers and other fields because of their good corrosion resistance and low price. However, galvanized steel sheets are prone to corrosion in humid environments, forming white corrosion products or turning gray on the surface, which affects the appearance quality of galvanized steel sheets and the corrosion resistance of the coating. Most of the traditional zinc coating passivation treatment uses hexavalent chromium compounds such as chromic acid and chromate as the treatment agent, which is called chromate passivation. It has simple process, good film bonding force, high corrosion resistance, and self-healing ability. However, because hexavalent chromium is carcinog...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/42C23C22/73
Inventor 朱忠良
Owner 朱忠良
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