High-temperature fixed-point furnace uncertainties.

High-temperature fixed-points with specified temperature values for phase transition temperatures and their uncertainties can be used to establish a temperature scale above the silver point as part of the SI. Current assigned temperatures had uncertainties increased to make the data consistent; seemingly with under-reported uncertainties which may have been due to variation in furnace thermal environment not being taken fully into account. As part of another round of temperature assignments to extend the available temperature options, the effect of changing furnace temperature gradients on the realization of different high-temperature fixed-point cells was investigated. The resulting uncertainty components are reported, and these should be included in any uncertainty budget. In this work, we present data for four phase transitions: iron-carbon (Fe-C), palladium-carbon (Pd-C), ruthenium-carbon (Ru-C) and tungsten carbide-carbon (WC-C). [ABSTRACT FROM AUTHOR]