This standard specifies the determination method of magnesium content in silver cadmium oxide electrical contact materials. This standard is applicable to the determination method of magnesium content in silver cadmium oxide electrical contact materials. Determination range: 0.010% to 0.050%. JB/T 7776.7-1995 Chemical analysis method for silver cadmium oxide electrical contact materials JB/T7776.7-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Method for chemical analysis of silver oxide pick electric contact materials Flame atomic absorption spectrometry for determination of magnesium content
1 Subject content and scope of application
This standard specifies the method for determination of magnesium content in silver oxide pick electric contact materials. JB/T7776.7—1995
This standard is applicable to the determination of magnesium content in silver fluoride pick electric contact materials. Determination range: 0.010%~0.050%. 2 Reference standards
GB772887
General rules for chemical analysis of metallurgical products Flame atomic absorption spectrometry JB4107.185 General rules and general provisions for chemical analysis methods of electric contact materials 3 Principle of the method
The sample is decomposed with nitric acid, and lanthanum salt is added to the dilute nitric acid medium to eliminate interference from related elements. Use air-acetylene flame to measure absorbance at a wavelength of 285.2nm on an atomic absorption spectrometer. 4 Reagents
4.1 Nitric acid (1+1).
4.2 Lanthanum nitrate solution (20g/L). Www.bzxZ.net
4.3 Magnesium standard stock solution: Weigh 0.1000g pure magnesium (99.95%) and place it in a 200mL beaker, add 5mL nitric acid (4.1), cover with a monitor, 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. This solution contains 0.1mg magnesium in 1mL.
4.4 Magnesium standard solution: Transfer 10.00mL magnesium standard stock solution (4.3) to a 200mL volumetric flask, add 2mL nitric acid (4.1), dilute to scale, and mix. This solution contains 5μg magnesium in 1mL. 5 Instruments
Atomic absorption spectrometer, with magnesium 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 concentration of magnesium to be characterized should not be greater than 0.005μg/mL. Precision: Measure the absorbance of the highest concentration standard solution 10 times, and calculate its absorbance average and standard deviation. The 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. The 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. See Appendix A (reference) for instrument working conditions. Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
6 Analysis steps
6.1 Test sample
Weigh 0.1g of test sample to the nearest 0.0001g. 6.2 Blank test
Perform a blank test with the test sample.
6.3 Determination
JB/T 7776.71995
6.3.1 Place the test sample (6.1) in a 100mL beaker, add 2mL of 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 100mL volumetric flask, add 3mL of nitric acid solution (4.2), dilute to the mark, and mix well. 6.3.2 Using air-acetylene flame, adjust the atomic absorption spectrometer to zero with water at a wavelength of 285.2nm, and measure the absorbance in parallel with the working curve solution series. Subtract the absorbance of the blank test. Find the corresponding magnesium concentration from the working curve. 6.4 Drawing of the working curve
6.4.1 Transfer 0, 2.00, 4.00, 6.00, 8.00, 10.00mL of magnesium standard solution (4.4) to a set of 100mL volumetric flasks, add 2mL of nitric acid (4.1) and 3mL of lanthanum nitrate solution (4.2), dilute to the scale, and mix. 6.4.2 Under the same conditions as the sample solution measurement, adjust the zero with water and measure the absorbance. Subtract the absorbance of the zero concentration solution. Draw the working curve with magnesium concentration as the horizontal axis and absorbance as the vertical axis. 7 Calculation of analysis results
The percentage of magnesium is calculated according to formula (1):
Mg(%)=C.V×10-
C—magnesium concentration obtained from the working curve, g/mL; where:
V.Total volume of the sample solution, mL;
—mass of the sample, g.
8 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table 1
0.010~0.025
>0.025~0.050
Allowable difference
JB/T7776.7-1995
Appendix A
Instrument working conditions
(reference)
The reference working conditions of the WFX-1F2 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 Guilin Electrical Science Research Institute of the Ministry of Machinery Industry. This standard was drafted and drafted by the State-owned No. 615 Factory. The main drafters of this standard are
Zhu Enli
Zhang Huanwen
Xing Guizhen
Air Flow
Ethernet Flow
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