GB/T 5167-1985 Determination of electrical resistivity of sintered metal materials and cemented carbides

This standard specifies the method for determining the resistivity of sintered metal materials and cemented carbides. It includes two measurement processes. One with a measurement accuracy of less than 0.30% is suitable for accurate determination of basic material properties; the other with a lower measurement accuracy is suitable for quality control in industrial production. GB/T 5167-1985 Determination of the resistivity of sintered metal materials and cemented carbides GB/T5167-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Sintered metal materials and hardmetals-Determination of electrical resistivityUDC 669-492.8
621.317.33
GB 5167--85
This standard specifies the method for determining the electrical resistivity of sintered metal materials and hardmetals. It includes two measurement processes. One measurement has an accuracy of less than 0.30% and is suitable for the precise determination of the basic properties of the material; the other has a lower measurement accuracy and is suitable for quality control in industrial production. 1 Terminology
The volume resistivity (hereinafter referred to as resistivity) of hardmetals is generally expressed in μ·cm. For a sample with uniform cross-section, the resistivity is determined by the following formula:
0=（RA/L）×106
Where: - — resistivity of the sample, μ·cm; R — resistance within the measuring length of the sample, 2; A — cross-sectional area of ​​the sample, cm2;
L — measuring length of the sample, cm\.
Note: The measuring length of the sample refers to the distance between the two potential contacts of the sample. 2 Samples
2.1 The sample can be a rod, bar or profile. The cross-section of the sample is required to be uniform and the cross-sectional area does not vary by more than 0.75%. 2.2 The resistance within the measuring length of the sample is not less than 0.000012. 2.3 For precise determination, the sample is required to be centerlessly ground with a diameter of 6.4mm and a length of 254mm. For general measurement, the distance between the potential contacts of the sample is required to be not less than 12.70mm and the cross-section is uniform. 2.4 The diameter, thickness, width or other dimensions of the sample should be compatible with the measuring range of the selected instrument. 2.5 The surface of the specimen shall be free of cracks or defects, and the oxide scale, dirt and oil on the surface shall be removed. 2.6 The specimen shall not be allowed to have overlaps or welds. 3 Instruments
When the resistance of the specimen is less than 12, use a Kelvin double-arm bridge or a potentiometer to measure the resistance. (1)
When the resistance of the specimen is 12 or greater than 1", use a Wheatstone bridge to measure the resistance. Hoopes conductivity bridge can also be used for measurement. 4 Measurement process
4.1 When measuring all dimensions and weight of the specimen, the measurement error of the instrument used shall not exceed 0.05%. In order to ensure the measurement accuracy of the measured length, the potential contact shall have a sharp blade; when contacting the potential contact of the specimen, appropriate pressure shall be applied to ensure stable and reliable contact.
4.2 When using a dry ruler to measure the cross-sectional area of ​​the specimen, each dimension shall be measured several times and the average value shall be taken. The dimension change shall not exceed 0.10". If the size is less than 2.54mm, the measurement accuracy cannot meet the specified accuracy requirements. In this case, the cross-sectional area of ​​the sample is determined by the weight, density and length of the sample.
National Bureau of Standards 1985-05-08 Issued
1986-02-01 Implementation
GB 5167 --85
4.3 When the density of the sample is unknown, it can be measured in accordance with GB3850-83 "Determination of Density of Sintered Metal Materials and Cemented Carbides". 4.4 When using a double-arm bridge or potentiometer to measure resistance, the distance between each potential contact of the sample and the corresponding current contact shall not be less than 1.5 times the circumference of the cross-sectional area of ​​the sample.
4.5 The wiring resistance between the standard resistor and the sample shall be significantly smaller than the resistance of the standard resistor and the sample. 4.6 The accuracy of measuring resistance is ±0.15%. To ensure the measurement accuracy, the standard resistor and the sample are required to be consistent with the ambient temperature. Because the test current causes the sample temperature to rise during the measurement process, the measured current should be as low as possible without affecting the accuracy, and the reading should be completed as soon as possible when the sample resistance does not change significantly. 4.7 In order to eliminate the influence of contact potential, two readings are used. The measurement current is read in the positive and reverse directions. 5 Temperature Correction
5.1 When measuring resistance, the test temperature is usually different from the reference temperature. In this case, the resistance can be corrected by the following formula: R=R./L1+α(tT)bzxz.net
W: Rr-
Resistance of the sample at reference temperature T, ;
R,-Resistance of the sample measured at temperature t, 2;ar
-Resistance temperature coefficient of the sample at reference temperature T;-Temperature when the resistance measurement is performed, C.
5.2 When the resistance temperature coefficient of the sample is unknown, the measurement environment is required to be 20±2℃. Report
The report shall include the following contents:
Sample number;
Material type of the sample,
Temperature during measurement;
Measured length of the sample;
Cross-sectional area of ​​the sample and its measurement method;
If necessary, record the weight of the sample;
Method for measuring resistance:
Resistance value;
Reference temperature;
Calculated value of resistivity at reference temperature;
Mechanical and heat treatment of the sample before measurement. Additional remarks:
This standard was proposed by the Ministry of Metallurgy of the People's Republic of China and China General Office of Nonferrous Metals Industry. This standard was drafted by the Powder Metallurgy Research Institute of Central South University of Mining and Metallurgy. The drafter of this standard was Zhao Laishun.
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