This standard specifies the determination method of zinc content in silver carbide tin oxide indium electrical contact materials. This standard is applicable to the determination of zinc content in silver carbide tin oxide indium electrical contact materials. Determination range: 0.05% to 1.00%. JB/T 7777.4-1995 Silver oxide tin oxide indium electrical contact material chemistry JB/T7777.4-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of silver oxide tin oxide electrical contact material PAN spectrophotometric method for determination of zinc content
1 Subject content and scope of application
This standard specifies the method for determination of zinc content in silver oxide tin oxide indium oxide electrical contact materials. JB/T7777.4—1995
This standard is applicable to the determination of zinc content in silver oxide tin oxide indium oxide electrical contact materials, with a determination range of 0.05% to 1.00%. 2 Reference standards
General rules for spectrophotometric methods for chemical analysis of metallurgical products GB7729—87
JB4107.1—85
3 Principle of the method
General rules and general provisions for chemical analysis methods of electrical contact materials The sample is decomposed with sulfur-nitric acid mixture, and silver is separated with sodium bromide. In the presence of OP, at pH 10, zinc (1) and PAN form a red complex, and its absorbance is measured at a wavelength of 555nm on a spectrophotometer. 4 Reagents
4.1 Mixed acid: 3 volumes of sulfuric acid (p.1.84g/ml) and 2 volumes of nitric acid (p1.42g/mL) are mixed. 4.2 Sodium bromide solution (200g/L).
4.3 Mixed masking agent: Weigh 2g of sodium citrate, 1g of sodium hexametaphosphate and 15g of sulfosalicylic acid and dissolve them in 100mL of water. 4.4 Diacetyl solution (10 g/L), prepared with ethanol. 4.5 Emulsifier OP solution (1 + 4).
4.6 Ammonium hydroxide (1 + 1).
4.7 Buffer solution: Weigh 5 g of disodium hydrogen phosphate and dissolve it in 100 mL of water. Use sodium hydroxide solution (10 g/L) to adjust the pH to 10 on the pH meter. 4.8 Copper reagent (DDTC) solution (6 g/L). 4.91 -(2-pyridyl azo)-2-naphthol (PAN) solution (1.0 g/L), prepared with ethanol. 4.10 Zinc standard stock solution: Weigh 0.1000 g of pure zinc (99.95%) and place it in a 150 mL beaker. Add 10 mL of nitric acid (1 + 1), cover with a watch glass, heat to dissolve completely, drive off nitrogen oxides, cool, rinse the surface blood and the wall of the beaker with water, transfer to a 1000 mL volumetric flask, dilute to the scale, and mix well. 1 mL of this solution contains 100 μg of zinc. 4.11 Zinc standard solution: Pipette 20.00 mL of zinc standard stock solution (4.10) into a 200 mL volumetric flask, dilute to scale with water, and mix. 1 mL of this solution contains 10 μg of zinc. bzxZ.net
4.12 Phenolic indicator (1.0 g/L), prepared with ethanol. 5 Instruments
Spectrophotometer.
6 Analysis steps
Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
6.1 Test materials
Weigh the test materials according to Table 1, accurate to 0.0001 g. Zinc
0.05~0.15
>0.15~0.40
>0.40~1.00
6.2 Blank test
Carry out a blank test with the sample.
6.3 Determination
JB/T7777.4—1995
6.3.1 Place the sample (6.1) in a 250mL conical beaker, add 20mL of mixed acid (4.1), heat until sulfuric acid smoke rises to the mouth of the beaker, and cool. 6.3.2 Wash the beaker wall with water to make the solution volume about 60mL, add 10mL of sodium bromide solution (4.2) while shaking continuously, heat and boil until the test solution is clear, and let it stand for 30 minutes.
6.3.3 Filter using two layers of qualitative filter paper with tilting method, wash the precipitate and the cup wall with water 4 times, wash the filter paper 3 times, collect the filtrate and washing liquid in a 250mL volumetric flask, dilute with water to scale, and mix well. 6.3.4 Take 10.00mL of the test solution and place it in a 100mL volumetric flask, add 10mL of mixed masking agent (4.3), 2mL of diacetyl solution (4.4), 0.5mL of phenol indicator (4.12), adjust with ammonia water (4.6) until the liquid is slightly red, add 10 drops of excess, add 5ml of buffer solution (4.7), 3mL of OP solution (4.5), 3.0mL of PAN solution (4.9), 3 drops of DDTC solution (4.8), dilute with water to scale, and mix well. 6.3.5 Transfer part of the solution into a 1cm cuvette, use water as a reference, and measure the absorbance at a wavelength of 555nm on a spectrophotometer. 6.3.6 Subtract the absorbance of the blank test and find the corresponding zinc content from the working curve. 6.4 Plotting the working curve.
6.4.1 Transfer 0, 2.00, 4.00, 6.00, 8.00, 10.00mL of zinc standard solution (4.11) to a group of 100mL volumetric flasks respectively, and proceed as in 6.3.4 to 6.3.5.
6.4.2 Subtract the absorbance of the reagent blank, and plot the working curve with the zinc content as the abscissa and the absorbance as the ordinate. 7 Calculation of analysis results
The percentage of zinc is calculated according to formula (1):
Zn(%)=m, ·V. ×10-s
Where: mi
-the zinc content found from the working curve, g;
V. -—Total volume of test solution, mL
V,—Volume of test solution taken, mL;
8Allowable difference
Mass of test material, g.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0.05~0.15
>0.15~0.40
>0.40~1.00
Additional notes:
JB/T7777.4-1995
This standard was proposed and managed by the Guilin Electrical Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Guilin Electrical Science Research Institute of the Ministry of Machinery Industry, and Guangzhou Electrical Alloy Factory participated in the drafting. The main drafters of this standard are Liu Yaoping
Lai Bingxin
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