This standard specifies the determination method of nickel content in silver cadmium oxide electrical contact materials. This standard is applicable to the determination method of nickel content in silver cadmium oxide electrical contact materials. Determination range: 0.05% to 0.50%. JB/T 7776.4-1995 Chemical analysis method for silver cadmium oxide electrical contact materials JB/T7776.4-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of silver cadmium oxide electrical contact material Flame atomic absorption spectrometry for nickel content
1 Subject content and scope of application
This standard specifies the method for determining the nickel content in silver cadmium oxide electrical contact material. JB/T 7776.4—1995
This standard is applicable to the determination of nickel content in silver cadmium oxide electrical contact material. Determination range: 0.05%~0.50%. 2 Reference standards
GB7728—87
General principles for chemical analysis of metallurgical products Flame atomic absorption spectrometry JB4107.1-85 General principles and general provisions for chemical analysis methods of electrical contact materials 3 Principle of the method
The sample is decomposed with nitric acid, and silver is separated by hydrochloric acid precipitation. In a dilute hydrochloric acid medium, an air-acetylene flame is used to measure the absorbance at a wavelength of 232.0nm on an atomic absorption spectrometer. Coexisting elements do not interfere with the determination. 4 Reagents
4.1 Nitric acid (1+1).
4.2 Hydrochloric acid (1+1).
4.3 Hydrochloric acid (1+19).
4.4 Nickel standard stock solution: Weigh 0.5000g pure nickel (99.95)% and place it in a 250mL beaker, add 20mL nitric acid (4.1), cover with a watch glass, heat at low temperature to dissolve, drive off nitrogen oxides, and cool to room temperature. Transfer to a 500mL volumetric flask, dilute to scale, and mix. This solution contains 1mg nickel in 1mL.
4.5 Nickel standard solution: Transfer 20.00mL nickel standard stock solution (4.4) to a 200mL volumetric flask, dilute to scale with hydrochloric acid (4.3), and mix. This solution contains 100 nickel in 1mL. 5 Instruments
Atomic absorption spectrometer with a nickel hollow cathode lamp. Under the best working conditions of the instrument, any instrument that can meet the following indicators can be used. Sensitivity: In a solution consistent with the matrix of the measured sample solution, the characteristic concentration of nickel should not be greater than 0.125ag/mL. Precision: Measure the absorbance of the highest concentration standard solution 10 times, and calculate its absorbance average and standard deviation. Its standard deviation should not exceed 1.0% of the absorbance average.
Measure the absorbance of the lowest concentration standard solution (not the "zero" standard solution) 10 times. And calculate its standard deviation. Its standard deviation should not exceed 0.5% of the average absorbance of the highest concentration standard solution. Working curve linearity: Divide the working curve into five sections according to concentration. The ratio of the difference in absorbance of the standard solution in the highest section to the difference in absorbance of the lowest standard solution should not be less than 0.7. See Appendix A (reference) for instrument working conditions. Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
Analysis steps
Weigh the sample according to Table 1, accurate to 0.0001g. Nickel content
0.05~0.25
>0.25~0.50
6.2 Blank test
Carry out a blank test with the sample.
6.3 Determination
JB/T7776.4—1995
6.3.1 Place the sample (6.1) in a 250mL beaker, add 5mL nitric acid (4.1), cover with table blood, heat at low temperature to dissolve, drive off nitrogen oxides, and cool to room temperature.
6.3.2 Wash the tableware and the wall of the cup to make the solution volume about 30mL, add 1mL hydrochloric acid (4.2), boil, make the silver chloride precipitate condense, and the solution transparent. Cool.
6.3.3 Filter the solution into a 100mL beaker with medium-speed filter paper, wash the beaker and precipitate with hot hydrochloric acid (2+98) 3 times, heat the test solution at low temperature and evaporate until about 2mL is left, remove it, and cool it to room temperature. Transfer it into a 100mL volumetric flask with hydrochloric acid (4.3) and dilute to the scale, mix well. 6.3.4 Use air-acetylene flame, adjust the atomic absorption spectrometer to zero with water at a wavelength of 232.0nm, measure the absorbance in parallel with the working curve solution series, and subtract the blank test absorbance. Find the corresponding nickel concentration from the working curve. 6.4 Drawing of working curve
6.4.1 Pipette 0, 2.00, 4.00, 6.00, 8.00, 10.00mL of nickel standard solution (4.5) into a set of 100mL volumetric flasks, dilute to scale with hydrochloric acid (4.3), and mix well. 6.4.2 Under the same conditions as the test solution measurement, adjust the absorbance to zero with water. Subtract the absorbance of the zero concentration solution, and draw the working curve with nickel concentration as the horizontal axis and absorbance as the vertical axis. 7
Calculation of analysis results
The percentage of nickel is calculated according to formula (1):
Ni(%)=
CThe nickel concentration obtained from the working curve, g/mL; Where:
The total volume of the test solution, mL
mThe mass of the test sample, g.
8 Allowable Difference
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
>0.15~0.30
>0.30~0.50
Allowable Difference
JB/T7776.4—1995Www.bzxZ.net
Appendix A
Instrument Working Conditions
(Reference)
The reference working conditions of the PE--3100 atomic absorption spectrometer are shown in Table A1. Table A1
Additional Notes:
Lamp Current
Burner Height
Spectral Bandwidth
This standard was proposed and managed by the Guilin Electric Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by the State-owned No. 615 Factory. This standard was drafted by the State-owned No. 503 Factory.
The main drafters of this standard are Yang Xiaodong
Li Bingkuan
Yu Xiaoguang
Air flow
Acetylene flow
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