Construction and Investigation of Pt/Pd Thermocouples in the Framework of the Euromet Project 857

Abstract

The objective of the EUROMET Project 857 in the field of thermometry, “High-temperature fixed points for improved thermocouple calibrations,” is the development of robust high-temperature fixed points based on metal-carbon eutectic alloys for the calibration of thermocouples above 1,084°C. This paper describes the construction and investigation of Pt/Pd thermocouples to be used to compare different cobalt–carbon (Co–C) fixed-point cells constructed by the three participants of this project. A set of three Pt/Pd thermocouples was prepared by PTB and NPL and a set of four by LNE. Their metrological performances in terms of thermoelectric stability and homogeneity were assessed in different ways. The results of these investigations, as well as the results of first measurements of local Co–C eutectic fixed-point cells by using Pt/Pd thermocouples, are presented.