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 results of chromium content can avoid the reduction and improve the accuracy.

Active Publication Date: 2009-03-25
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 an 800ml beaker 2 SO 4 , and then put in a sample of Φ=80mm, and stir continuously at 20-25°C to dissolve until the sample is exposed to the substrate metal. Transfer the solution and eluent together into a 100ml volumetric flask to constant volume and shake well. This solution is the total volume V of the sample solution.

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

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

[0014] 4. Dry filter the above solution with a filter...

Embodiment 2

[0019] 1. Add 30ml of 30% H in an 800ml beaker 2 SO 4 , and then put in a sample of Φ=80mm, and stir continuously at 20-25°C to dissolve until the sample is exposed to the substrate metal. Transfer the solution and eluent together into a 100ml volumetric flask to constant volume and shake well. This solution is the total volume V of the sample solution.

[0020] 2. Transfer an appropriate volume (with a chromium content between 10 and 1000 μg) of the above solution into a 250ml Erlenmeyer flask for heating and boiling, add 5ml of 1% potassium permanganate solution, continue to boil until the manganese dioxide is completely precipitated, cool, and rinse with water Dilute to 80-90ml.

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

Embodiment 3

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

[0027] 2. To the above solution, slowly add 35% sodium bicarbonate solution in batches under stirring, until precipitation occurs, then excess 5ml, slowly heat and boil for 2-3min, cool to room temperature with running water, transfer to a 250ml volumetric flask, dilute to volume, 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 filtrate (the chromium content is between 2 and 40 μg) into a 250ml volumetric flask, dilute to 80 to 90ml with water, add 25ml of 35% phosphate buffer, add 40% H 2 SO 4 Solution 3ml and 0.5% diphenylcarbazide indicator (solvent: 94ml ethanol and 6ml glacial ace...

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PUM

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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 detection method of chemical element content, which is suitable for the detection method of Cr in chromate conversion film on the surface of galvanized series products, in particular to a detection method of total Cr content in chromate solution containing zinc sulfate. Background technique [0002] The chromium on the surface of the galvanized sheet is a passivation film added to the galvanized sheet after galvanizing. Hexavalent chromium is highly toxic and carcinogenic. Under the impetus of environmental protection, clean production and automobile industry's higher requirements on the corrosion resistance of product parts, it is very important to accurately analyze the content of Cr on the surface of galvanized sheets. meaning. At present, GB / T9791-2003 "Test method for chromate conversion coating of zinc, cadmium, aluminum-zinc alloy and zinc-aluminum alloy" is the method used by domestic enterprises to detect the Cr con...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/78G01N1/34
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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