Design, Construction, and Evaluation of Ni–C Eutectic Fixed Points

In this article the design, construction, and evaluation of eutectic fixed points for contact and non-contact measurements that have been recently developed at MIRS/UL/FE-LMK are presented. The design of the cells is made in such way that it can be used for only thermocouple calibration in vertical or horizontal furnaces, for calibration of pyrometers in a horizontal furnace, and for simultaneous calibration of contact and non-contact thermometers in a horizontal furnace. Special care has been taken to achieve repeatability and reproducibility of the transition temperatures and mechanical robustness of the cell. This includes also usage of a carbon sleeve in combination with carbon sheets, in a so-called hybrid design of the eutectic cell. With such a design, significant improvement in mechanical robustness of the cell and temperature stability of the cell has been achieved. All the measurements are performed within specially designed seven-zone furnaces within which different gradients, and different heating and cooling rates can be realized. The melting temperature of Ni–C ((1328.44 ± 0.70) °C) measured with a thermocouple type R, calibrated at the zinc, aluminum, silver, copper, and palladium fixed points, and a non-contact thermometer, calibrated by comparison against different blackbodies, agree within their expanded uncertainties of 0.7 °C and 1.5 °C, respectively.