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Total cr content detection method in zinc sulfate contained chromate solution

A detection method and chromate technology, applied in the preparation of test samples, material analysis by observing the influence of chemical indicators, and analysis by chemical reaction of materials, etc., can solve the problem of large errors and heavy detection results. Problems such as poor performance and large error in the detection result of chromium content can improve the accuracy and avoid the reduction

Active Publication Date: 2011-06-01
ANGANG STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the actual detection process, when dissolving the chromate conversion coating, the zinc layer will inevitably be dissolved to varying degrees. The test results have large errors and poor reproducibility
In summary, in order to solve the problems of large errors and poor reproducibility of the above-mentioned Cr detection results, the key is to establish a detection method for the total Cr content in the chromate solution that can eliminate the influence of zinc sulfate.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0011] 1. Add 30ml of 30% H in a 800ml beaker 2 SO 4 , And then put the sample with Φ=80mm, stir continuously at 20~25℃ to dissolve, until the dissolution is finished when the sample exposes the substrate metal. Transfer the dissolving solution and the eluent into a 100ml volumetric flask to a constant volume and shake it up. This solution is the total volume V of the sample solution.

[0012] 2. Transfer the appropriate volume (chromium content between 10 and 1000 μg) of the above solution into a 250ml Erlenmeyer flask, add 0.1g ammonium persulfate and 17g / l silver nitrate solution 3ml, boil for 30min, cool, and dilute with water to 80~ 90ml.

[0013] 3. To the above solution, slowly add 2% sodium carbonate solution in portions under stirring, until precipitation occurs, and then 5ml excess, slowly heat and boil for 2~3min, cool the running water to room temperature, transfer it to a 250ml volumetric flask, dilute the volume and shake well .

[0014] 4. Use a 40μm pore size filter...

Embodiment 2

[0019] 1. Add 30ml of 30% H in a 800ml beaker 2 SO 4 , And then put the sample with Φ=80mm, stir continuously at 20~25℃ to dissolve, until the dissolution is finished when the sample exposes the substrate metal. Transfer the dissolving solution and the eluent into a 100ml volumetric flask to a constant volume and shake it up. This solution is the total volume V of the sample solution.

[0020] 2. Transfer the appropriate volume (chromium content between 10 and 1000μg) of the above solution into a 250ml Erlenmeyer flask and heat it to boil, add 5ml of 1% potassium permanganate solution, continue to boil until all the manganese dioxide is precipitated, cool and use water Dilute to 80~90ml.

[0021] 3. To the above solution, slowly add 20% sodium carbonate solution in batches with stirring until precipitation occurs and then 5ml excess, slowly heat and boil for 2-3min, cool the running water to room temperature and transfer it to a 250ml volumetric flask, dilute the volume and shake w...

Embodiment 3

[0026] 1. Transfer an appropriate volume of chromate solution containing zinc sulfate (with chromium content between 10 and 1000μg) into a 250ml conical flask, add 0.1g ammonium persulfate and 17g / l silver nitrate solution 3ml, boil for 30min, Cool and dilute with water to 80~90ml.

[0027] 2. To the above solution, slowly add 35% sodium bicarbonate solution in portions with stirring until precipitation occurs and then 5ml excess, slowly heat and boil for 2~3min, cool the running water to room temperature and transfer it to a 250ml volumetric flask, make the volume constant, shake uniform.

[0028] 3. Use No. 3 microporous sand core to dry filter the above solution.

[0029] 4. Pipette an appropriate amount of the above-mentioned filtrate (chromium content between 2-40μg) into a 250ml volumetric flask, dilute with water to 80-90ml, add 25ml of 35% phosphate buffer, and add 40% H 2 SO 4 Solution 3ml and 0.5% diphenylcarbazide indicator (solvent 94ml ethanol and 6ml glacial acetic aci...

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Abstract

The invention discloses a method for detecting the total Cr content in a chromate solution which contains zinc sulfate, which comprises the following steps of oxidation, color development, determination and so on in the prior art, and is characterized in that the influence of the zinc sulfate on detection of the total Cr content in the chromate solution is eliminated through two steps, namely precipitation and separation after the chromate solution which contains the zinc sulfate undergoes oxidation, and then color development and determination are performed. The detection method solves the problem that the Cr testing result is greatly influenced by the zinc sulfate in the chromate solution through addition of the two steps, namely the precipitation and the separation, thereby avoiding reduction of the Cr testing result, improving the accuracy of the testing result and making the testing result reach more than 90 percent of the nominal value.

Description

Technical field [0001] The invention relates to a method for detecting the content of chemical elements, which is suitable for the method for detecting Cr in the chromate conversion film on the surface of galvanized series products, in particular to a method for detecting the total Cr content in a chromate solution containing zinc sulfate. Background technique [0002] The chromium on the surface of the galvanized sheet is a passivation film added after the galvanized sheet is finished. Hexavalent chromium is highly toxic and carcinogenic. Driven by environmental protection, the realization of clean production, and the higher requirements of auto workers for the corrosion resistance of product parts, it is very important to accurately analyze the Cr content on the surface of galvanized sheets. Meaning. At present, GB / T 9791-2003 "Test Method for Chromate Conversion Coating of Zinc, Cadmium, Aluminum-Zinc Alloy and Zinc-Aluminum Alloy" is the method used by domestic enterprises t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N1/34G01N21/78
Inventor 陈义庆徐承明徐小连肖宇杨春雨武裕民李新
Owner ANGANG STEEL CO LTD
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