Caractérisation des couples thermoelectriques platine/palladium: influence de la composition des fils

摘要

Four platinum versus palladium thermocouples were built at the BNM-LNE in order to study the influence of the wires extraction (two different providers of wire were selected to supply metals). The thermocouples were calibrated three times successively at the fixed points of the ITS-90 within the temperature range from 0 ℃ to I 064℃. ,4 metallographic study showed that no detectable microstructure changes in the wires occured during the test. Under these conditions, the platinum versus palladium thermocouple calibration results were compared with published reference functions established by BNM-INM and PTB. Values deviated widely depending upon the origin of the wires. Finally, the representativeness of the thermocouples were evaluated according to the two reference functions used. Measurements stemed from this study were joined to the BNM-INM measurements in order to establish a new reference function for this type of thermocouples.