This standard specifies the determination method of total carbon content in silver tungsten carbide electrical contact materials. This standard is applicable to the determination of total carbon content in silver tungsten carbide electrical contact materials. Determination range: 2.00% to 5.00%. JB/T 7778.3-1995 Chemical analysis method for silver tungsten carbide electrical contact materials JB/T7778.3-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of silver tungsten carbide electric contact material Gas volumetric method for determination of total carbon content
1 Subject content and scope of application
This standard specifies the method for determination of total carbon content in silver tungsten carbide electric contact material. JB/T 7778. 3----1995
This standard is applicable to the determination of total carbon content in silver tungsten carbide electric contact material. Determination range: 2.00%～5.00%. 2 Reference standards
GB 223.1-81
JB 4107. 1--85
3 Principle of the method
Determination of carbon content in steel and alloys
General principles and general provisions for chemical analysis methods of electrical contact materials The sample is placed in a high-temperature furnace for heating and burning with oxygen to oxidize carbon into carbon dioxide. The mixed gas is collected in a gas measuring tube, and then the carbon dioxide is absorbed by potassium hydroxide solution. The difference in volume before and after absorption is the volume of carbon dioxide, from which the carbon content is calculated. 4 ReagentsbzxZ.net
4.1 Sulfuric acid (p 1.84 g/mL).
4.2 Potassium hydroxide solution (400g/L).
4.3 Sodium chloride solution (260g/L).
4.4 Acidic sodium chloride solution: Take 800mL of sodium chloride solution (4.3), add a few drops of methyl red solution (4.6), and use sulfuric acid (4.1) to adjust the solution to red.
4.5 Potassium hydroxide-potassium permanganate wash solution: Take 30 grams of potassium hydroxide and dissolve it in .70mL of saturated potassium permanganate solution and mix well. 4.6 Methyl red solution (1g/L).
4.7 Anhydrous calcium chloride.
4.8 Alkali asbestos (granular).
4.9 Silver vanadate: Weigh 11.7z ammonium vanadate and dissolve it in 400mL of hot water. Take another 17g of silver nitrate and dissolve it in 200mL of water. Pour the silver nitrate solution slowly into the ammonium vanadate solution and stir to produce a yellow precipitate. Filter it and wash the precipitate with water until there is no silver ion in the solution. Dry it in a drying oven at 110℃, grind it into granules, and sieve out fine particles of 1-3mm for use. 5 Instruments and Equipment
5.1 Carbon determination device is shown in the figure below.
Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
JB/T 7778.3---1995
Oxygen cylinder, 2-oxygen flow regulator, 3-drying tower, with alkali asbestos (4.8) in the lower part and anhydrous calcium oxide (4.7) in the upper part; 4-gas washing bottle: containing potassium hydroxide-potassium permanganate washing solution; 5-buffer bottle; 6-gas washing bottle: containing sulfuric acid (4.1), 7-three-way piston, 8-tube furnace + 9 temperature controller, 10-filter: containing absorbent cotton a-desulfurizer: containing silver vanadate (4.9), b-cooling tube, c-three-way piston, d-three-way piston, e-gas measuring tube, f-level bottle: containing sodium hydroxide acid solution (4.4), g-thermometer, h-absorber: containing potassium hydroxide solution (4.2). 5.2 Alumina porcelain boat: 88mm long, burned at 1200℃ for 2h. Cool to room temperature and store in a desiccator for use. 5.3 Alumina porcelain tube: 600mm long, 22mm inner diameter. Burn in sections at working temperature before use. 5.4 Long hook: 500mm long. Made of low carbon alloy wire. Used to push and pull porcelain boats. s.5 Atmospheric pressure gauge.
6 Analysis steps
Weigh the sample according to Table 1, accurate to 0.0001g. Table 1
Carbon content
2. 00~~3.00
>3. 00 ~5. 00
6.2 Blank test
Carbon content ... 6.4 Determination
6.4.1 Place the sample in the porcelain boat (5.2), push it into the highest temperature in the furnace with a long hook (5.4), immediately plug the rubber stopper, preheat for 1 min, operate according to the instrument operating procedures, and read the reading. 6.4.2 Open the rubber stopper, pull out the porcelain boat with the long hook, and then analyze the next sample. 65
7 Calculation of analysis results
The percentage of carbon is calculated according to formula (1):
Where: C Reading when burning the sample, %, Co Reading of the blank test, %
JB/T 7778. 3-1995
(CC)? K
K-temperature and pressure correction coefficient, [see Appendix of GB223.1], m Mass of the sample, g.
8Tolerance
The difference in the analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
2.00~3.00
>3. 00~5.00
Additional Notes:
This standard was proposed and managed by the Guilin Electric Science Research Institute of the Ministry of Machinery Industry. X100
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This standard was drafted by the Guilin Electric Science Research Institute of the Ministry of Machinery Industry, and the Shanghai Electric Science Research Institute participated in the drafting. The main drafters of this standard are Tang Yuelin, Huang Liuqing, and 66
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