A high temperature test rig to simultaneously measure electrical conductivity and thermopower is described. The apparatus allows to perform measurements in controlled atmosphere or vacuum to protect oxygen sensitive materials. A spring load mounting placed in a cold zone permits to reduce the thermal contact resistance between the sample and two metallic blocks (the hot side and the heat sink) even at high temperature. The hot side metal block is periodically heated to obtain the thermopower from the slope of the ?V vs ?T line. Conductivity is measured before each thermopower measurement by a linear four-wire method. The automatic data acquisition and analysis is controlled by a LabView-based interface. Two interchangeable setups are possible. The first one uses silver blocks and K-type thermocouples and is suitable for temperatures from 300 to about 1100 K. The second one uses W blocks and S-type thermocouples to allow higher temperatures measurements since all the hot zone parts are made of Al2O3, Pt or W. The device was tested using PdAg alloy and Ni rods and, for the low temperatures range, the NIST Standard Reference Material 3451 (bismuth telluride), strictly confirming the reference data.
Test rig for high temperature thermopower and electrical conductivity measurements
S Boldrini;A Famengo;F Montagner;S Battiston;S Fiameni;M Fabrizio;S Barison
2012
Abstract
A high temperature test rig to simultaneously measure electrical conductivity and thermopower is described. The apparatus allows to perform measurements in controlled atmosphere or vacuum to protect oxygen sensitive materials. A spring load mounting placed in a cold zone permits to reduce the thermal contact resistance between the sample and two metallic blocks (the hot side and the heat sink) even at high temperature. The hot side metal block is periodically heated to obtain the thermopower from the slope of the ?V vs ?T line. Conductivity is measured before each thermopower measurement by a linear four-wire method. The automatic data acquisition and analysis is controlled by a LabView-based interface. Two interchangeable setups are possible. The first one uses silver blocks and K-type thermocouples and is suitable for temperatures from 300 to about 1100 K. The second one uses W blocks and S-type thermocouples to allow higher temperatures measurements since all the hot zone parts are made of Al2O3, Pt or W. The device was tested using PdAg alloy and Ni rods and, for the low temperatures range, the NIST Standard Reference Material 3451 (bismuth telluride), strictly confirming the reference data.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
