Development of High-Temperature Blackbodies and Furnaces for Radiation Thermometry

Two high-temperature blackbodies were developed and tested. The first one is a graphite blackbody with a maximum temperature of 2000 °C, an opening of 40 mm, and an emissivity of 0.995. It is intended for the routine calibration of pyrometers. The second one is a small version of a pyrolytic graphite (PG) blackbody with a cavity diameter of 15 mm, an opening of 10 mm, and an emissivity of 0.9996. The blackbody has two options with maximum temperatures of 2500 °C and 3000 °C, respectively. With these, the list of high-temperature blackbodies developed at VNIIOFI consists of five PG types and one graphite type, which can be used in radiation thermometry as precision Planckian sources or furnaces for fixed-point applications. The article also describes modifications to the PG furnace, where PG heater rings are replaced partly or totally by graphite elements. Such modifications extend the lifetime of the heater, reduce the cost for some applications and, for some cases, improve the temperature uniformity.