This standard specifies the determination method of magnesium content in silver zinc oxide electrical contact materials. This standard is applicable to the determination of magnesium content in silver zinc oxide electrical contact materials. Determination range: 0.010% to 0.100% JB/T 7774.5-1995 Chemical analysis method for silver zinc oxide electrical contact materials JB/T7774.5-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of silver zinc oxide electric contact material Determination of magnesium content by flame atomic absorption spectrometry
1 Subject content and scope of application
This standard specifies the determination method of magnesium content in silver zinc oxide electric contact material JB/T 7774.5-1995
This standard is applicable to the determination of magnesium content in silver zinc oxide electric contact material. Determination range: 0.010%~0.100%. 2 Reference standards
GB772887
JB4107.1-85
3 Principle of method
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 The sample is decomposed with nitric acid, and lanthanum salt is added to the dilute nitric acid medium to eliminate the interference of elements such as aluminum () and silicon (V). Use air-acetylene flame to measure the 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/1).
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 blood, heat at low temperature to dissolve, drive off nitrogen oxides, and cool to room temperature. Transfer to a 1000ml volumetric flask and dilute to scale. Mix well. This solution contains 0.1mg magnesium per ml.
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), and dilute to scale. Mix well. This solution contains 5μg magnesium per ml. 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 measured sample solution, the characteristic concentration of magnesium should not exceed 0.005μg/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 between the absorbance of the standard solution in the highest section and the absorbance of the standard solution in the lowest section should not be less than 0.7.
For instrument working conditions, see Appendix A (reference). Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
6 Analysis steps
6.1 Test material
Weigh the test material according to Table 1, accurate to 0.0001g. Magnesium content
0.01~0.05
>0.05~0.10
6.2 Blank test
Perform a blank test with the test material.
JB/T7774.5—1995
6.3.1 Place the test material (6.1) in a 100ml beaker, add 10ml nitric acid (4.1), cover with surface blood, heat at low temperature to dissolve, drive off nitrogen oxides, and cool to room temperature. Wash the surface blood and the wall of the beaker with water, transfer to a 100ml volumetric flask, and dilute to the scale. Mix well. 6.3.2 Take 20.00 ml of the sample solution and place it in a 100 ml volumetric flask. Add 3 ml of nitric acid solution (4.2) and dilute to the mark. Mix well. Using an air-acetylene flame, adjust the wavelength to 285.2 nm with water at the atomic absorption spectrometer. Measure the absorbance in parallel with the standard solution (6.4.1) series 6.3.3
. Subtract the blank test absorbance and find the corresponding magnesium concentration from the working curve. 6.4 Drawing of the working curve
6.4.1 Take 0, 2.00, 4.00, 6.00, 8.00, 10.00 ml of the magnesium standard solution (4.4) and place them in a group of 100 ml volumetric flasks respectively. Add 2 ml of nitric acid (4.1) and 3 ml of nitric acid solution (4.2) and dilute to the mark and mix well. 6.4.2 Adjust the wavelength to zero with water and measure the absorbance under the same conditions as the sample solution. 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. Calculation of analysis results
The percentage of magnesium is calculated as follows:bZxz.net
CV. .V,.10-.
Mg(%)=
Where:
C—the magnesium concentration found from the working curve, ug/ml; V. —the total volume of the sample solution, ml,
V,——the diluted volume of the sample solution after aliquoting, ml; V,——the volume of the aliquoted sample solution, ml; m-
Allowable difference
—the mass of the sample, g.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0.010~0.050
>0.050~0.100
JB/T7774.5—1995
Appendix A
Instrument working conditions
(reference)
Use WFX-IF, type atomic absorption spectrometer reference working conditions as shown in Table A1. Table A1
Additional notes:
Burner height
Monochromator passband
This standard was proposed and coordinated by the Guilin Electric Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by Shanghai Alloy Material General Factory. This standard was drafted by the State-owned No. 615 Factory.
Wang Enli Yu Xiaoguang
Main drafters of this standard
Xing Guizhen
Air flow
Acetylene flow
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