GB/T 5167-2018Sintered metal materials and hardmetals—Determination of electrical resistivity (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard replaces GB/T 5167-1985 "Determination of resistivity of sintered metal materials and cemented carbides".

Compared with GB/T 5167-1985, the main technical contents of this standard are changed as follows.

--- Added Chapter 1 "Scope";

--- Added Chapter 2 "Regular References";

--- Remove the terminology description for the 1985 version;

--- Chapter 4 "Instruments" increases the range and accuracy requirements of vernier calipers, lever micrometers, thermometers, precision balances;

--- Chapter 6, "Measurement Results and Calculations" adds "mass resistivity" and "unit length resistance";

--- Chapter 7 "Temperature Correction" was changed to "Correction of Resistance Value";

--- Chapter 8, "Test Report" optimizes and supplements related content.

1 Scope

This standard specifies the determination of the electrical resistivity of sintered metal materials and cemented carbides.

This standard applies to the following two methods for determining the electrical resistivity of sintered metal materials and cemented carbides.

a) A measurement accuracy of less than 0.30%, suitable for accurate determination of the basic properties of the material;

b) A low measurement accuracy for quality control in industrial production processes.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this document. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 1216 outer diameter micrometer

GB/T 3850 dense sintered metal material and method for determination of density of cemented carbide

GB/T 21389 cursor, table and digital caliper

3 Sample

3.1 The specimen may be a rod, strip or profile, and its diameter, thickness, width or other dimensions shall be compatible with the measuring range of the selected instrument, and The surface should be uniform and the cross-sectional area should not change by more than 0.75%.

3.2 The resistance within the length of the sample measurement shall be not less than 0.00001 ohm. For accurate measurement, the sample shall be ground and polished to a diameter of 6.4 mm. The length is 254mm; for general measurement, the distance of the potential contact of the sample should be not less than 12.70mm, and the cross section is uniform.

3.3 The surface of the sample shall be free of scale, dirt and oil. There shall be no cracks or defects. The test shall not allow overlap and weld.

4 Instruments

4.1 When the sample resistance is less than 1ohm, measure the resistance with the Calvin double-arm bridge; when the sample resistance is 1ohm or more, use the Wheatstone bridge Measure the resistance.

4.2 Vernier caliper. (1000 ± 0.1) mm, should meet the requirements of GB/T 21389. Lever micrometer. the indication error of the meter does not exceed 1µm, should meet the requirements of GB/T 1216.

4.3 Thermometer. The indication error does not exceed 0.1 °C.

4.4 Precision balance. The division value is 0.1mg.

5 Measurement process

5.1 Measuring the length and quality of the sample, the measurement error of the instrument used is not more than ± 0.05%. In order to ensure the accuracy requirements of the measurement length, The potential contact should have a sharp edge. When it is in contact with the potential contact of the sample, it should have a proper clamping force to ensure stable and reliable contact.

5.2 When measuring the cross-sectional area of the sample, the cross-sectional area is measured 5 times or more in equidistant distance within the gauge length of the sample, and the average value is taken. test The sample size does not change by more than 0.10%. If the sample size is less than 2.54mm and the measurement accuracy does not meet the specified accuracy requirements, the sample is cut off. […]