This standard specifies the method for determining the copper content in copper tungsten carbide vacuum contact materials. This standard is applicable to the determination of copper content in copper tungsten carbide vacuum contact materials. Determination range: 15.00% to 55.00%. JB/T 7775.2-1995 Chemical composition of copper tungsten carbide vacuum contact materials JB/T7775.2-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of copper tungsten and tungsten carbide vacuum contact materials. Determination of copper content by complexometric titration
1 Subject content and scope of application
This standard specifies the method for determining the copper content in copper tungsten and tungsten carbide vacuum contact materials. JB/T7775.2—1995bzxZ.net
This standard is applicable to the determination of copper content in copper tungsten and tungsten carbide vacuum contact materials. Determination range: 15.00%~55.00%. 2 Reference Standards
JB4107.1-85 General Rules and General Provisions for Chemical Analysis Methods of Electrical Contact Materials 3 Summary of Methods
After the sample is decomposed by sulfuric acid-ammonium sulfate, tungsten is masked with tartrate. In the hexamethylenetetramine buffer solution, excess EDTA solution is added, and xylenol orange is used as an indicator. The lead standard solution is used for back titration. Then, thiourea-ascorbic acid-o-phenanthroline combined demasking agent is added to release the EDTA complexed with copper. The copper amount is calculated from the titrated volume. 4 Reagents
4.1 Sulfuric acid (p1.84g/mL).
4.2 Ammonium sulfate: solid.
4.3 Nitric acid (1+1).
4.4 Potassium sodium tartrate solution (100g/L). 4.5 Sodium hydroxide solution (200g/L).
4.6 Hexamethylenetetramine solution (200 g/L). 4.7 Sulfur gland solution (80 g/L).
Ascorbic acid solution (100 g/L), freshly prepared. 4.8
Phenanthroline ethanol solution (2 g/L).
Copper standard solution: weigh 2.0000 g pure copper (99.95%) and dissolve it in 20 mE nitric acid (4.3), remove nitrogen oxide, transfer to a 1000 mL volumetric flask, dilute to scale, and mix. This solution contains 0.0020 g copper in 1 mL. 4.11
Disodium ethylenediaminetetraacetic acid (EDTA) solution: 0.03 mol/L, weigh 11.2 g EDTA and dissolve it in water and dilute to 1 liter, mix 4.12 Preparation and calibration of lead standard solution. 4.12.1 Prepare 0.02 mol/L, weigh 7.69 g of lead acetate (Pb(CH.COO), ·3H,O) and dissolve it in 100 mL of water, add 20 mL of glacial acetic acid, stir until the solution is clear, transfer to a 1000 mL volumetric flask, dilute to the mark with water, and mix well. 4.12.2 Calibration: Accurately transfer the copper standard solution (4.10) with a copper content similar to that of the sample into a 250 mL conical flask, add excess EDTA solution (4.11), and proceed as per steps 5.2.2 to 5.2.3. The concentration of lead standard solution equivalent to copper is calculated according to formula (1): C
Wherein:
Concentration of lead standard solution equivalent to copper, g/mL; C
Approved by the Ministry of Machinery Industry on October 9, 1995
Implementation on January 1, 1996
JB/T7775.2-1995
V. Weigh the volume of copper standard solution, mL; C. Concentration of copper standard solution, g/mL;
V,--the volume of lead standard solution consumed in titrating copper standard solution, mL. 4.13 Xylenol orange indicator (abbreviated as X0) (2g/L). 5 Analysis steps
5.1 Test sample
Weigh 0.1 test sample, accurate to 0.0001g. 5.2 Determination
5.2.1 Place the sample in a 250mL conical flask, add 5mL sulfuric acid (4.1), 2g ammonium sulfate (4.2), heat to dissolve, cool, add about 50mL water, add 5mL potassium sodium tartrate solution (4.4), shake well. 5.2.2 Add EDTA solution (4.11) according to the copper content and add 3~5mL excess (1mL EDTA solution is equivalent to about 1.9mg copper), adjust the solution to blue (precipitate dissolves, pH~4) with sodium hydroxide solution (4.5), add 10mL hexamethylenetetramine solution (4.6), 4~5 drops of X0 indicator (4.13), and titrate with lead standard solution (4.12) to blue-purple as the first end point, without counting. 5.2.3 Add 20mL of thiourea solution (4.7), 5mL of ascorbic acid solution (4.8), and 10 drops of o-phenanthroline solution (4.9), and then titrate with the lead standard solution until the light purple color does not fade as the end point, and record the titration volume. Calculation of analysis results
The percentage of copper is calculated according to formula (2):
Cu(%)=
Where: C-the concentration of copper equivalent to the lead standard solution, g/mL; X100
V-the volume of the lead standard solution consumed in the second titration, mL; -test material, g.
7 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table 1
15.00~30.00
>30.00~55.00
Additional Notes:
This standard was proposed and managed by Guilin Electric Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by Shanghai Electric Science Research Institute of the Ministry of Machinery Industry. This standard was participated in by Tianshui Changcheng Electrical Alloy Material Factory. The main drafters of this standard were Huang Liuqing, Song Zhanfa, Zhao Guangying, 20
Zhang Qingyi
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