This standard specifies a method for determining the chlorine content of flexible graphite sheets using the combustion-mercury thiocyanate spectrophotometric method. JB/T 6622-1993 Method for determination of chlorine content in flexible graphite plates JB/T6622-1993 Standard download and decompression password: www.bzxz.net

J22 | | tt | | JB | Published
Ministry of Machinery Industry of the People's Republic of China
Published
Implemented on 1994-01-01
Machinery Industry Standard of the People's Republic of China
Chlorine content of flexible graphite plates Determination method
Subject content and scope of application
JB/T 6622-93
This standard specifies the determination of chlorine content in flexible graphite plates using the combustion-mercury thiocyanate spectrophotometric method. method. This standard is applicable to the determination of chlorine content in flexible graphite plates, and its linear concentration range is 1 to 100 Ppm. 2 Method summary
The sample is ashed to remove carbon. The chloride decomposes at high temperature to produce hydrogen cyanide gas, which is absorbed by perhydride oxygen. Then the fluoride ions react with mercury mercaptocyanate to generate mercuric fluoride and dissociate. Equivalent of thiocyanate, which forms a red complex with iron ions, thereby determining the chlorine content spectrophotometrically.
3 Reagents
3.1 Vegetable mercury cyanate solution (0.5%),
Weigh 0.5g of thiocyanate in a 250mL beaker, add 100mL of methanol to dissolve it and filter it into a brown bottle Medium, the validity period is 1 month.
3.2 Iron nitrate is dissolved in c[Fe(No,),·9H,O]=30%. Weigh 150g of ferric nitrate into a 500mL beaker, add 280mL of concentrated nitric acid and a small amount of water, dissolve and dilute to 500mL, store in a brown bottle,
sodium hydrochloride (excellent grade pure) solution (4%). 3.3
3.4
Hydrogen peroxide (10%).
3.5 concentrated sulfuric acid (density 1.84g/mL).
3.6 potassium hydroxide (40%)
3.7 chlorine-free distilled water, that is, steamed stuffing water that has been redistilled twice. 3.8 Chlorine standard solution
3.8.1 Weigh 0.2103g potassium fluoride (spectrally pure) and place it in a 250mL beaker, dissolve it with an appropriate amount of water, transfer it to a 1000mL volumetric flask, dilute it with water to the mark, shake the hook, and this solution The chlorine content is 100g/mL. 3.8.2 Pipette 10mL of fluorine standard solution (according to Article 3.8.1) and place it in a 100mL volumetric flask, dilute to the mark with water and shake well. The chlorine content of this solution is 10ug/mL.
4 Instruments and Equipment
a.
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Quartz tube (or porcelain tube): 600mm long, 18mm inner diameter: Quartz boat (or porcelain boat): 100mm long, 12mm wide, 10mm high; Quartz evaporated blood (or porcelain evaporated): Capacity 30mL: Absorption Bottle (see Figure 1):
Spectrophotometer:
Tubular high-temperature furnace with temperature control device, thermocouple and temperature indicating instrument approved by the Ministry of Machinery Industry on 1993-05-07||tt ||1994-01-01 Implementation
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5 Preparation of samples
JB/T6622-93
Figure 1
5.1 Submission plate The weight is not less than 20g, and its surface should be clean and free of oil and dust. 5.2 Take 3 square specimens of the same size equidistantly along the diagonal direction of the inspection plate. The total weight is not less than 10g: 5.3 Use the quartering method Divide each of the three samples into two equal parts, one part is the test sample and the other part is the reserved sample. 5.4 Cut the sample into pieces with stainless steel scissors, dry them flat in an oven at 105~110°C, and then place them in a desiccator to cool for later use. 6 Analysis steps
6.1 Connect all parts of the test device according to Figure 2, Figure 2 Test device diagram
1-Oxygen cylinder: 2-Oxygen pressure gauge: 3-Flow meter; 4-40% hydrogen Potassium oxide scrubber gas bottle: 5-concentrated pickling gas bottle: 6-dry coal tower, containing silica gel: 1-high virtual burner tube, 8-high-temperature combustion furnace, 9-porcelain life (quartz boat), 10-temperature Controller (with thermocouple): 11, 13 - Absorption bottle 6.2 Adjust the temperature controller to raise the furnace temperature to 900 ± 20°C. Open the oxygen valve and check whether the device is airtight. Note; use a bomb to connect one end of the absorption condensation to the atmosphere. Tighten the clamp and open the clamp at the oxygen inlet. If there are no bubbles, the device is considered airtight. 6.3 Weigh 0.5~1.0g sample (depending on the chlorine content) to the nearest 0.0002g, and place it in a porcelain boat that has been pre-fired at 900°C. 6.4 Add 2 mL of peroxide absorption solution to the absorption bottles. 6.5 Push the porcelain boat containing the sample into the high-temperature part of the furnace center with a nickel-chromium wire hook, and then burn the furnace with oxygen at a rate of 150~200mL/min for 12~15 minutes. Stop the oxygen flow.
6.6 Rinse the absorption bottle with a small amount of water and mix it into the evaporated blood. Add 0.5mL sodium nitroxide solution, evaporate to about 2mL and cool, rinse with a small amount of water and transfer it to a 25mL colorimetric tube.
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JB/T6622-93
6.7 Push the blank porcelain boat into the high-temperature part of the furnace center, and perform the blank test according to steps 6.5 to 6.6. 6.8 In the colorimetric tube Add 1mL ferric nitrate solution and 2mL thiocyanate solution respectively, dilute to the mark with water. Shake evenly. After 10 minutes, pour the solution into a 3cm thick cuvette. Use water as the reference solution and set it at 460nm on the spectrophotometer. Measure its absorbance. 7 Drawing of working curve
7.1 Take 0, 0.5, 1.0, 3.05.0, 7.0, 9.0mL chlorine standard solution (according to Article 3.8.2) and place them in seven 25mL colorimetric tubes respectively. Article 6.8 Measure the absorbance,
7.2 minus the blank value, take the absorbance as the ordinate and the required content as the abscissa, and draw a working curve. 8 Calculation of analysis results
After subtracting the blank absorbance from the measured absorbance of the sample, find the oxygen content from the working curve. 8.1
8.2 Calculate the content (CI) in the sample according to the following formula
In the formula: C1 - chlorine content, Ppm;
A - chlorine content obtained by checking the working curve, rgm - sample mass·g.
8.3 Take the average of two or more parallel analysis results. 9 Allowable difference
Cl
m
The difference between two parallel analysis results should be less than the allowable difference listed in the table below, ppm
including
1 ~10
>10~50
>50
10 test report internal guest
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Material name, brand, specification, manufacturer : Test name, sample number, number;
Commissioning unit:
Test results:
Test unit, test date, test personnel. Additional notes:
This standard is proposed and administered by Hefei General Machinery Research Institute of the Ministry of Machinery Industry. Charge
This standard is drafted by the Mechanical Carbon Products Research Institute of Sichuan Zigong Dongxindian Carbon Plant. The main drafters of this standard are Dai Yingqi and Xu Jinfang. Xu
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Difference
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