JB/T 5351-1991 Test methods for basic properties of vacuum switch contact materials

This standard specifies the basic performance test methods for the density, hardness, conductivity and gas (oxygen, nitrogen) content of vacuum switch contact materials (the gas content test method is only applicable to copper-chromium contact materials). JB/T 5351-1991 Basic performance test methods for vacuum switch contact materials JB/T5351-1991 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Basic Performance Test Methods for Vacuum Switch Contact Materials·Subject Content and Scope of Application
JB5351-91
This standard specifies the basic performance test methods for density, hardness, electrical conductivity and gas oxygen and nitrogen content of vacuum switch contact materials (the gas content test method is only applicable to copper-chromium contact materials). 2
Cited Standards
GB5586
Test Methods
Basic Performance Test Methods for Electrical Contact Materials
Metal Brinell Hardness Test Methods
Density Measurement
Density measurement shall be carried out in accordance with GB5586.
Hardness Measurement
Hardness measurement shall be carried out in accordance with GB231.
3.3 Conductivity measurement
Measurement principle
Put the detection wire on the metal block, and the electromagnetic field of the wire will induce a current on the metal surface. The magnitude of the current is related to the conductivity of the metal being measured. Since the value of the instrument has been calibrated with the known conductivity standard block in advance, the absolute value of the conductivity of the sample can be directly read from the instrument. 3.3.2
Measurement instrument
Select an eddy current conductivity meter with a measurement range of 5-62S/M. Sample requirements
The sample surface should be free of oil and obvious oxidation, and the diameter of the flat part should be greater than 10mm; the surface roughness parameter Ra value of the measured part is: 6.3μm.
Sample measurementwww.bzxz.net
Before measurement, calibrate repeatedly with the conductivity high and low value standard blocks according to the instrument manual. When the sample is less than Φ30mm, measure three times on the front and back of its center (see Figure 1). When the sample is Φ30mm or larger, three points are measured on both sides along the diameter direction (see Figure 2). 3.3.5 Measurement results
The conductivity of the sample is the arithmetic mean x (S/m) of the 6 measured values. Result representation:
.. a. arithmetic mean;
b. standard deviation.
3.4 ​​Measurement of oxygen and nitrogen gas content
3.4.1 Measurement principle
Use inert atmosphere pulse heating to melt the sample in the stone measuring pot, and measure the oxygen (in the form of CO or CO2) and nitrogen (N2) in the sample by infrared absorption spectroscopy and thermal conductivity method respectively. The basic principle of infrared absorption spectrum measurement is Lambert-Beer's law, and its mathematical expression is: Approved by the Ministry of Machinery and Electronics Industry on June 28, 1991 and implemented on July 1, 1992
Where:
E—absorbance
Io—incident light intensity
I—transmitted light intensity
L—optical path length
C-gas concentration
JB5351-91
K—absorption coefficient of certain gases at a certain concentration. -KCL
The basic principle of thermal conductivity measurement is the Wheatstone bridge principle, and its measurement principle diagram is shown in Figure 3: Figure
Signal recorder
V-bridge voltage
R,, R,
A measurement arm resistance
A measurement output
Reference arm resistance
Figure: 2
Reference arm output
3.4.2 Measuring instrument
JB5351-91
This standard specifies the use of infrared and thermal conductivity gas analyzers. 3.4.3 Sample measurement steps
3.4.3.1 Measurement preparation
Heating element: Spectral pure standard graphite crucible, size see Figure 4. Carrier gas:
Ammonia (purity ≥ 99.99%)
Hydrogen (purity ≥ 99.99%)
Power gas: nitrogen, compressed air or hydrogen standard, sample: solid standard or gas standard
3.4.3.2 Sampling
The sample is processed into a cuboid or cylinder.
The sample weight is 0.5~1g (the weighing accuracy is not less than one thousandth). 3.4.3.3 Sample processing
The tools used for sample preparation must not be rusted and should be cleaned with ethanol or acetaldehyde before use. After the sample processing is completed, use tetrafluoroethylene or trichloroethylene to remove oil stains, use benzene to dehydrate, and dry it with cold air before analysis and measurement. The sample surface should be free of macroscopic defects, clean, oil-free, and free of oxidation. 3.4.3.4 Instrument calibration
The analytical instrument should be calibrated before sample measurement. The method is referred to the instrument manual. 3.4.3.5 Sample measurement
Degassing current: 1100A (temperature equivalent to 2400℃)11
5351-91
Analysis current: 975～1075A (temperature equivalent to 2100～2300℃)3.4.4 Measurement results
The sample must be measured three times in a row under the same measurement conditions and its arithmetic mean value X (ppm) is taken. The results are expressed as follows:
Arithmetic mean value;
Standard deviation.
Additional notes:
This standard was proposed and managed by the Guilin Electrical Science Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the Guilin Electrical Science Research Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Hu Xian, Qiu Bin,12
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