[0148] Example 1
[0149] In this embodiment, use such as figure 1 The detection device shown and follow figure 2 Connect the sample to be tested in a lap connection mode to detect the thermoelectric performance parameters of the sample to be tested.
[0150] specific, figure 1 In the testing device shown, the three test lines are parallel suspension laps, and their endpoints are connected to heat sink 51, heat sink 52, heat sink 53, heat sink 54, heat sink 55, and heat sink 56 respectively. The vertical suspension is lapped on the test line, and the heating line is connected to the overlap point 1, the first induction line is connected to the overlap point 2, and the second induction line is connected to the overlap point 3, and the overlap point 1 , Overlap point 2 and overlap point 3 divide the test line and the sample to be tested into test line 11, test line 12, test line 21, test line 22, test line 31, test line 32, upper section 41 of the sample to be tested, and Test the eight parts of the lower section 42 of the sample.
[0151] In the specific detection steps, the experimental device needs to be placed in a vacuum constant temperature environment (the vacuum degree is 10 -3 Pa below), the high temperature end of the sample to be tested is generated by the direct current heating heating wire, part of the heat is conducted along the sample to be tested, and is transferred to the heat sink through the test line 21, the test line 22, the test line 31 and the test line 32. The temperature is consistent with the ambient temperature. The ambient temperature is detected and controlled by the temperature controller, with a control accuracy of ±0.1K; with the help of the first and second sensing lines, the resistance changes are measured to determine the contact points at the overlap point 2 and the overlap point 3. temperature change.
[0152] During the test, first obtain the resistance of the first induction wire and the second induction wire at ambient temperature without heating with electricity, and then apply direct current on the heating wire. Due to the Joule heating effect, a high temperature end will be generated, and part of the heat will pass through the The test sample is transferred to the heat sink through the test line 21, the test line 22, the test line 31 and the test line 32. After reaching a steady state, a linear temperature distribution is generated on the above four test lines, and the temperature distribution is generated at the overlap point 2 and the overlap point 2. There is a steady-state temperature difference between contact 3, and the resistance of the test line has a good corresponding relationship with temperature. The temperature rise at lap 2 and lap 3 can be obtained by measuring its resistance, and the heat flow relationship at lap 3 is used The thermal properties of the second induction line can determine the thermal conductivity of the sample to be tested; for thermoelectric materials, the steady-state temperature difference between the overlap point 2 and the overlap point 3 will produce a DC Seebeck voltage, which can be used with a high-precision digital voltmeter Obtain the voltage signal directly, use the first induction line and the second induction line to determine the steady-state temperature difference to obtain the Seebeck coefficient of the sample to be tested; without heating, change the circuit to connect the test line 21, test line 22, and test line The wire 31 and the test wire 32 are regarded as wires, and the resistance of the sample to be tested can be measured to obtain its conductivity. Since this method uses three test wires as heating wires and induction wires for measurement, it is named the three-wire method.
[0153] Among them, reference image 3 , The thermal conductivity measurement circuit consists of a DC power supply 5 and a heating wire to form a closed loop, which generates heat through electric heating; a DC power supply 6, a standard resistance 8 and the first induction wire form a closed loop, which is detected by high-precision digital voltmeters 10 and 11, respectively The standard resistance 8 and the voltage across the first sensing line further obtain the resistance of the first sensing line; the DC power supply 7, the standard resistance 9 and the second sensing line form a closed loop, and the standard resistance is detected by high-precision digital voltmeters 12 and 13 respectively 9 and the voltage across the second sensing line to further obtain the resistance of the second sensing line.
[0154] Among them, reference Figure 4 When the Seebeck coefficient is measured thermally, the high-precision digital voltmeter 10, the test line 22, the lower section 42 of the sample to be tested and the test line 32 form a closed loop. When the DC power supply 5 is energized and the heating line is on, the overlap point 2 is measured The DC Seebeck voltage generated by the thermocouple formed by the measured material and the induction line between the junction 3 and the junction 3.
[0155] Among them, reference Figure 5 , The conductivity measurement circuit is composed of a DC power supply 6, a test line 31, a lower section 42, a test line 21, and a standard resistance 8 in series to form a closed loop. The high-precision digital voltmeter 10 is used to obtain the test line through the test line 22 and the test line 32. For the voltage at both ends of the lower section 42 of the sample, the voltage at both ends of the standard resistor 8 is obtained by the high-precision digital voltmeter 11, and the resistance of the lower section 42 of the sample to be tested is calculated to obtain its conductivity.
[0156] According to the formula: λ=λ 3 A 3 l 3 l 42 R 02 β T2 ΔR 3 /A 4 l 31 l 32 (ΔR 2 R 03 β T3 -ΔR 3 R 02 β T2 ) Determine the thermal conductivity of the sample to be tested; according to the formula: S * =V S R 02 β T2 R 03 β T3 /(ΔR 2 R 03 β T3 -ΔR 3 R 02 β T2 ) Determine the Seebeck coefficient of the thermocouple formed by the sample to be tested and the induction line, and further according to the formula: S=S * +S s Determine the Seebeck coefficient of the sample to be tested; according to the formula: σ = l 42 /R 42 A 4 Determine the conductivity of the sample to be tested.
[0157] Where λ 3 Is the thermal conductivity of the second induction wire, A 3 Is the cross-sectional area of the second induction line, A 4 Is the cross-sectional area of the sample to be tested, l 3 Is the length of the second induction line, l 42 Is the length of the lower section 42 of the sample to be tested, l 31 Is the length of the 31 segments of the test line, l 32 Is the length of the test line 32 segments, R 02 Is the resistance of the first induction line at a temperature of 0℃ (273.15K), R 03 Is the resistance of the second induction line at 0℃ (273.15K) temperature, β T2 Is the temperature coefficient of resistance of the first induction line at ambient temperature T, β T3 Is the resistance temperature coefficient of the second induction line at ambient temperature T, △R 2 Is the resistance change of the first induction wire after energized heating, △R 3 Is the resistance change of the second induction wire after energized heating, V S Is the DC Seebeck potential of the thermocouple formed by the lower section 42 of the sample to be tested and the induction line, S s Is the Seebeck coefficient value of the first and second induction lines, R 42 Is the resistance of the lower section 42 of the sample to be tested.
[0158] The thermal conductivity test results of this embodiment, such as Figure 8 Shown. From Figure 8 It can be seen that the thermal conductivity of the tested material platinum rhodium 13 alloy is 25.3W m in the temperature range of 200-300K. -1 K -1 To 38.4W m -1 K -1 , The overall measurement result has high accuracy, and the measurement uncertainty is 8%. .
[0159] The detection result of Seebeck coefficient of this embodiment, such as Picture 9 Shown. From Picture 9 It can be seen that in the temperature range of 200-300K, the Seebeck coefficient of the thermocouple formed by the measured material platinum-rhodium 13 alloy and the induction wire material platinum is 3.1μVK -1 Increased to 6.3μV K -1 , The measurement uncertainty is 5%; after eliminating the influence of platinum on the induction line, the Seebeck coefficient of the tested material platinum-rhodium 13 alloy is overall from 1.6μV K -1 Reduced to 1.1μV K -1 , The maximum absolute error is 0.4μV K -1 , With very high resolution.
[0160] The conductivity detection result of this embodiment, such as Picture 10 Shown. From Picture 10 It can be seen that in the temperature range of 200-300K, the conductivity of the tested material platinum rhodium 13 alloy ranges from 3.9×10 6 S m -1 Reduced to 3.3×10 6 S m -1 , The measurement uncertainty is 3%.
[0161] Compared with the prior art, the present invention separates the heating end from the test end, so at the overlap point 2 and the overlap point 3, the heat is transferred from the sample to be tested to the test line, and the contact thermal resistance is at the overlap point 2. It is the same as the deviation direction of the error generated at the overlap point 3. Through compensation, the actual temperature difference between the overlap point 2 and the overlap point 3 on the test line and the measured temperature difference between the overlap point 2 and the overlap point 3 on the induction line , That is, the error caused by the contact thermal resistance is greatly reduced, and the measurement accuracy is improved; on the basis of a sample overlap, the thermal conductivity, electrical conductivity and Seebeck coefficient of the sample to be tested can be obtained sequentially by changing the measurement circuit. Comprehensive characterization of the thermoelectric performance of the sample to be tested has a high degree of integration. The invention has the advantages of high measurement accuracy, easy realization and low test cost.
