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Zinc layer trivalent chromium iridescent passivation treating fluid used under normal temperature and usage method thereof

A technology of passivation treatment and trivalent chromium, applied in the coating process of metal materials, etc., can solve the problems of rough surface of passivation film, existence of micropore defects, unfavorable repeated use, etc., and achieve good anode protection and surface compactness High, the effect of improving uniformity and corrosion resistance

Active Publication Date: 2019-08-27
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide an efficient and stable zinc layer trivalent chromium color passivation treatment solution at room temperature and its preparation and use method, which can be made into a stable film layer in one step and improve the corrosion resistance and convenience of use of the passivation treatment solution When the existing trivalent chromium passivation treatment solution is used to passivate the surface of galvanized parts, the treatment time is long and the energy consumption is high. The passivation solution is easy to deteriorate and is not conducive to repeated use. The surface of the obtained passivation film is rough and has micropores. Defects and other technical issues

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  • Zinc layer trivalent chromium iridescent passivation treating fluid used under normal temperature and usage method thereof
  • Zinc layer trivalent chromium iridescent passivation treating fluid used under normal temperature and usage method thereof
  • Zinc layer trivalent chromium iridescent passivation treating fluid used under normal temperature and usage method thereof

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Effect test

Embodiment 1

[0043] In this embodiment, the preparation method of the trivalent chromium color high-efficiency passivation treatment liquid for zinc layer at normal temperature, the steps are as follows:

[0044] First, under the condition of continuous stirring, dissolve 15-20g of chromium trichloride in part of deionized water; then, add 5-10g of sodium nitrate, 8-15g of malonic acid, 15-20g of citric acid, 5- After fully dissolving 10g of sodium dihydrogen phosphate, add 8-15g of thiourea and make it fully dissolve, heat to 50°C, add 0 or 0.8g of cerous sulfate and stir until completely dissolved, then add 0.8-1.5g of ferrous sulfate, and finally Then add the remaining amount of deionized water, and let it stand for 24 hours to get a kind of zinc layer trivalent chromium high-efficiency passivation treatment solution at room temperature, adjust the passivation treatment with 10wt% sodium hydroxide aqueous solution and 10wt% nitric acid solution The pH value of the solution was 2.2, and ...

Embodiment 2

[0061] In this example, the test experiment of the electrochemical corrosion performance of the passivation layer adopts a three-electrode system. The passivation package sample A obtained in Example 1 is used as the working electrode, and the counter electrode is a 20mm×20mm×0.5mm Pt sheet, on which the The Φ0.5mm Pt lead wire is sealed and insulated with a polytetrafluoroethylene (PTFE) tube, and the reference electrode is a KCl saturated calomel electrode (SCE). Configure CHI660D Electrochemical Workstation (produced by Shanghai Chenhua Instrument Co., Ltd.), and carry out the potentiodynamic polarization curve test to the modified passivation film that the above-mentioned embodiment 1 control test obtains in the sodium chloride aqueous solution of concentration 3.5wt%, the result sees figure 2 . Before adding Ce, the corrosion current of the film layer was 5.331×10 -6 A·cm 2 , through linear fitting, the corrosion resistance is 2122Ω·cm 2 ; After adding Ce, the passiva...

Embodiment 3

[0063] Such as image 3 (a)-(b), using OLYMPUS Z61 stereoscope to scan the surface structure of the passivation film obtained at pH 2.2, from the passivation film processed with zinc layer trivalent chromium color high-efficiency passivation treatment solution at room temperature As can be seen from the stereoscopic view of the film, compared with the passivation film obtained by non-cerium treatment in Example 1, the passivation film obtained after the surface passivation containing rare earth cerium is more uniform, and the surface of the passivation film is obviously smoother. And the porosity of the passivation film is lower. The surface porosity was calculated from the surface topography photos, and the porosity decreased from 10% to about 4% after Ce-containing treatment.

[0064] The results of the examples show that the present invention adds Ce(IV) salt to the Cr(III) green treatment solution to modify the passivation film during the normal temperature growth process...

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Abstract

The invention relates to the technical field of metal surface passivating treatment, in particular to a zinc layer trivalent chromium iridescent passivation treating fluid used under normal temperature and a usage method thereof. Based on calculation per liter, the zinc layer trivalent chromium iridescent passivation treating fluid consists of 15-20g of chromium trichloride, 5-10g of sodium nitrate, 8-15g of propane diacid, 15-20g of citric acid, 5-10g of sodium dihydrogen phosphate, 8-15g of thiourea, 0.8-1.5g of ferrous sulfate, 0.6-1.0g of cerium sulfate and the balance of deionized water.Under a continuous stirring condition, the chromium trichloride is dissolved in a part of the deionized water, the sodium nitrate, the propane diacid, the citric acid, the sodium dihydrogen phosphateand the thiourea are sequentially added and fully dissolved, the cerium sulfate is added and stirred to completely dissolve, the ferrous sulfate and the remaining deionized water are added, and the zinc layer trivalent chromium iridescent passivation treating fluid is obtained after standing. The zinc layer trivalent chromium iridescent passivation treating fluid has the characteristics of being capable of performing normal temperature treatment, simple and convenient, easy to control, stable and the like, and a colored passive film bright, uniform and compact, and good in corrosion resistancecan be obtained by passivating an encapsulated galvanized sample under the condition that PH (potential of hydrogen) value is 2.2 in a laboratory.

Description

technical field [0001] The invention relates to the technical field of metal surface passivation treatment, in particular to a high-efficiency and stable zinc layer trivalent chromium modified color passivation treatment liquid for normal temperature and a preparation and use method. Background technique [0002] Metal surface galvanizing is one of the effective ways to improve the anticorrosion effect of steel, aluminum alloy and other metals. However, in humid and hot environments, the surface of the galvanized layer will corrode and produce white rust, which will detach and penetrate into the substrate, thereby affecting the appearance and corrosion resistance of the galvanized layer. At present, the passivation treatment process is generally performed on the galvanized layer, and a passivation film is added to improve its corrosion resistance. The traditional hexavalent chromium passivation film has the advantages of good corrosion resistance and high decoration, and ha...

Claims

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Application Information

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IPC IPC(8): C23C22/10
CPCC23C22/10
Inventor 刘侠和李洪旭王来滨刘宇李凤华王梅
Owner NORTHEASTERN UNIV
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