Abstract
Above the freezing temperature of silver, the International Temperature Scale of 1990 (ITS-90) is defined using Planck's law of blackbody radiation. Since the temperature is determined by ratio of its emitted radiance against the radiance from Ag, Au, or Cu freezing-point blackbody, uncertainty of the scale increases rapidly with increasing temperature. To solve this problem, AIST has been developing high-temperature fixed points of metal-carbon alloys. In this text, introduction of ITS-90 and high-temperature fixed point using metal-carbon alloys, melting and freezing behaviors of these fixed points under various conditions, and application of these fixed points for thermocouple calibration are presented.
https://ror.org/01703db54 
