Simultaneous Contact and Non-contact Measurements of the Melting Temperature of a Ni–C Fixed-Point Cell

A novel fixed-point cell design that allows simultaneous measurements using contact and non-contact thermometers was developed and investigated at PTB to realize the nickel-carbon (Ni–C) fixed-point. The melting temperature indicated by the LP3 radiation thermometer amouInted to (1328.86±0.52)◦C (k =2). The melting temperature of the Ni–C fixed-point cell was also calculated by extrapolating the emf-temperature characteristics of two Pt/Pd thermocouples based on their calibrations at conventional fixed points of the ITS-90. The melting temperature of the Ni–C eutectic amounts to (1328.44±0.45)◦C using thermocouple Pt/Pd 01/04, and to (1328.53±0.46)◦C using thermocouple Pt/Pd 01/05, with uncertainties for k =2. The contact and non-contact thermometers agree well within the combined uncertainties.