Miniature iron-carbon eutectic point crucible for the calibration of thermometers

The article presents the design, construction and evaluation of a miniature graphite iron-carbon eutectic point crucible for the calibration of thermometers. These are either contact such as thermocouples or non-contact such as infrared thermometers. The double wall of the crucible protects its structure in case of cracks in graphite that can appear due to thermal expansion or eutectic adhesion. Such design proved robust – even after almost 100 melting realizations, the crucible does not show significant signs of damage. Performance of the crucible was confirmed with several realized plateaus at three different furnace setpoints. Results of these measurements agree with previously published findings. The measured melting point temperature was 1153.81 °C and the achieved expanded calibration uncertainty of a type R thermocouple was 0.2 °C.