GB/T 3248-1982 Copper, nickel and their alloys - Determination of resistivity

This standard is applicable to the determination of the resistivity of copper, nickel and their alloys. GB/T 3248-1982 Method for determination of the resistivity of copper, nickel and their alloys GB/T3248-1982 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determining method of resistivity ofcopper, nickel and their alloys This standard applies to the determination of resistivity ofcopper, nickel and their alloys. 1 Definition
:621.317.33
GB 3248-82
The resistance value of a sample with a length of 1m and a cross-sectional area of ​​1mm2 is the resistivity of the sample)(2·mm2/m). It is expressed as follows:
Where: R——resistance value of the sample, α (ohm); S
——cross-sectional area of ​​the sample, mm2 (millimeter 2); 1——length of the sample, m (meter).
2 Instruments and equipment
Bridge (or potentiometer) with an accuracy of more than 0.5% (and periodically certified by the national metrology agency) and matching galvanometer.
2.2 Standard resistance set.
The lower scale with an accuracy of 0.01 and 0.001. 2.4F
There are two types of resistance fixtures: 1000mm and 200mm. Its accuracy should be guaranteed to be above 1mm. 2.5
Suitable DC power supply.
3 Preparation of test specimenswwW.bzxz.Net
3.1 The test specimen must be a wire, strip or bar with uniform cross section. The resistance value of the test specimen should be above 0.012. Except for special circumstances. 3.2 The length of the test specimen can be determined according to the specifications of the material, the hardness and softness of the material and the specifications of the fixture. 3.3 The appearance of the test specimen shall be checked with the naked eye, and no scars, cracks or knots are allowed. 3.4 Plates, strips and bars shall be milled into specimens with a width of 4 to 8mm and a length of 300mm. The width along the entire length of the test specimen shall not vary by 5%. 4 Determination of resistance
4.1 According to the estimated value of the sample resistance, select single or double bridges and standard resistors (single bridge for samples above 10α, double bridge for samples below 10α). Samples below 10α must be equipped with two pairs of terminals for current and voltage. The minimum distance between each voltage terminal and its adjacent current terminal shall not be less than three times the wire diameter, or the width of the strip, belt or sheet; and sufficient current terminals shall be provided to prevent the sample from heating up. 4.2. Selection of working current: The working current passing through the sample shall not cause the sample to heat up, and the change in the sample resistance shall not be more than 0.2% of the sample resistance, that is, the working current should be as small as possible while ensuring the sensitivity. To verify whether the working current passing through the sample is appropriate, the test current can be increased by 1.4 times, and the resistance can be measured and compared with the resistance without increasing the current. If the difference is less than 0.5% of the resistance value, it proves that the current is appropriate, otherwise the working current should be reduced. 4.3 Measure the resistance R and record the measurement environment temperature. The National Bureau of Standards issued on June 21, 1982, and implemented on March 1, 1983. Measurement of cross-sectional area GB324882 is carried out over the entire length of the sample. (Distance between voltage terminals) 3 to 5 or more equally divided points are measured and the average value is taken. The wire and the material should be straight? (If the cross-sectional area is elliptical, the cross-sectional area is ab; if the cross-sectional area is rectangular, the cross-sectional area is the width multiplied by the thickness). The cross-sectional area of ​​​​the special-shaped materials and filaments with uniform cross-sections can be measured by weighing. 6 Result processing
Substitute the measured data into the formula in Chapter 1 of this standard to obtain the resistivity β value. Additional remarks:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Shenyang Nonferrous Metal Processing Plant. From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB798-71 "Test Method for Resistivity of Nonferrous Metal Copper-Nickel Alloy" shall be used.
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