GB/T 41079.2-2022Test methods for physical properties of liquid metals—Part 2: Determination of electrical conductivity (English PDF)

3.1 Cell constant

Cell constant refers to the ratio of the distance between the electronic probes to the cross-sectional area of the sample.

NOTE: the unit is (mm/mm²).

7.1 Parallel Test

Independently carry out two determinations and take the average value.

7.2 Calibration of Cell Constant

When using a new quartz conductivity cell, the cell constant shall be calibrated. The calibration of the cell constant shall be carried out in accordance with the stipulations of Appendix A.

7.3 Determination

7.3.1 The sample shall be melted in advance. Before loading into the quartz conductivity cell, use a glass rod to remove the surface oxide layer.

7.3.2 Put the pre-melted sample into the quartz conductivity cell and ensure that there are no air bubbles in the sample in the quartz conductivity cell; put the quartz conductivity cell into the high-temperature thermostatic bath and use a supporting device to properly fix it. In accordance with Figure 1, connect the constant-current power supply, voltmeter and probes.

7.3.3 Immerse the thermocouple into the sample, turn on the high-temperature thermostatic bath and raise the temperature to the test temperature; maintain the temperature stable for more than 15 min.

7.3.4 Adjust the lifting device, so that the ends of the four probes are immersed in the sample.

7.3.5 Start the constant-current power supply and input a constant DC current (I) of 1 A to the sample, after the reading of the digital voltmeter becomes stable, measure the voltage between the two electronic probes and record it as U1; reversely input a constant DC current (I) of 1 A, after the reading of the digital voltmeter becomes stable, measure the voltage between the two electronic probes and record it as U2. Take the average value of U1 and U2 and record it as U.

8.1 Calculation of Electrical Resistivity

The electrical resistivity of the sample, which is expressed in r, is calculated in accordance with Formula (1):

Where, r---the electrical resistivity of the sample, expressed in (µohm·m);

U---the value of the voltage drop between the electronic probes, expressed in (mV);

C---the value of the conductivity cell constant calibrated with the reference sample, expressed in (mm/mm²);

I---the constant current passing between the current probes, expressed in (A) (I = 1.00 A).

The calculation result is expressed in three decimal places, and the rounding off of the value shall be carried out in accordance with the stipulations of GB/T 8170.

8.2 Calculation of Electrical Conductivity

The electrical conductivity of the sample, which is expressed in sigma, is calculated in accordance with Formula (2):

Where, sigma---the electrical conductivity of the sample, expressed in (MS/m).

The calculation result is expressed in two decimal places, and the rounding off of the value shall be carried out in accordance with the stipulations of GB/T 8170.