This standard specifies the determination method of cadmium content in silver cadmium oxide electrical contact materials. This standard is applicable to the determination method of cadmium content in silver cadmium oxide electrical contact materials. Determination range: 5.00% to 25.00%. JB/T 7776.2-1995 Chemical analysis method for silver cadmium oxide electrical contact materials JB/T7776.2-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of silver oxide radium electric contact material Flame atomic absorption spectrometry to determine the amount of cadmium
1 Subject content and scope of application
This standard specifies the method for determining the amount of cadmium in silver oxide radium electric contact material. JB/T7776.2—1995
This standard is applicable to the determination of the amount of cadmium in silver oxide radium electric contact material. Determination range: 5.00%～25:00%. 2 Reference standards
GB7728-87
General principles of flame atomic absorption spectrometry for chemical analysis of metallurgical products General principles and general provisions for chemical analysis methods of electric contact materials JB4107.185
3 Principle of the method
The sample is decomposed with nitric acid, and the absorbance is measured at a wavelength of 228.8nm on an atomic absorption spectrometer using an air-acetylene flame in a dilute nitric acid medium. Coexisting elements do not interfere with the determination. 4 Reagents
4.1 Nitric acid (1+1).
4.2 Radium standard solution: Weigh 0.3000g pure radium (99.95%) and place it in a 250mL beaker, add 20mL nitric acid (4.1), cover with blood, heat at low temperature to dissolve, drive off nitrogen oxides, and cool to room temperature. Transfer to a 1000mL volumetric flask, dilute to scale, and mix well. This solution contains 0.3mg radium in 1mL.
5 Instruments
Atomic absorption spectrometer with radium 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 sample solution, the burner turns 90, and the characteristic concentration of cadmium should not be greater than 0.15μg/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 average absorbance.
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 standard solution in the lowest section should not be less than 0.7. For instrument working conditions, see Appendix A (reference). 6 Analysis steps
6.1 Test materials
Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
Weigh the test materials according to Table 1, accurate to 0.0001g. Cadmium content
5.00~15.00
>15.00~25.00
6.2 Blank test
Carry out a blank test with the sample.
6.3 Determination
JB/T7776.2—1995
Volume aliquot
6.3.1 Place the sample (6.1) in a 100mL beaker, add 3mL nitric acid (4.1), cover with table blood, heat at low temperature to dissolve, drive off nitrogen oxides, and cool to room temperature. Transfer to a 100mL volumetric flask, dilute to scale, and mix. 6.3.2 Take the sample solution according to Table 1, add 3mL nitric acid (4.1) to a 100mL volumetric flask, dilute to scale, and mix. 6.3.3 Using air-acetylene flame, at the wavelength of 228.8nm of the atomic absorption spectrometer, turn the burner 90°, adjust to zero with water, and measure the absorbance in parallel with the working curve solution series. Subtract the absorbance of the blank test and find the corresponding concentration from the working curve. 6.4 Drawing of the working curve
6.4.1 Transfer 0, 1.00, 2.00, 3.00, 4.00, 5.00mL of cadmium standard solution (4.2) to a set of 100mL volumetric flasks, add 3mL of nitric acid (4.1) to each, dilute to the scale, and mix. 6.4.2 Under the same conditions as the sample solution measurement, adjust to zero with water and measure the absorbance. Subtract the absorbance of the zero concentration solution. Draw the working curve with cadmium concentration as the horizontal axis and absorbance as the vertical axis. Calculation of analysis results
The percentage of cadmium is calculated according to formula (1):
Cd(%):
Wherein:
CV. .V,X10-*
Cadmium concentration obtained from the working curve g/mL; C
V. Total volume of sample solution, mL
V—volume of solution during determination, mL;
V,-—volume of sample solution taken, mL;
mMass of sample, g.
8Tolerance
The difference in analysis results between laboratories should not be greater than the tolerance listed in Table 2. Table 2
5.00~10.00
>10.00~15.00
>15.00~20.00
>20.00~25.00
Allowancewww.bzxz.net
JB/T7776.2—1995
Appendix A
Instrument working conditions
(reference)
The reference working conditions for using WFX-ID atomic absorption spectrometer are as follows. Table A1
Additional notes:
Lamp current
Burner height
Light passband width
This standard was proposed and managed by 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 Shanghai Electric Science Research Institute of the Ministry of Machinery Industry. The main drafters of this standard are Huang Liuqing
Li Yongkang
Air flow
B fast flow
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