Development of metal–carbon high-temperature fixed-point blackbodies for precision photometry and radiometry

Abstract

High-temperature fixed-point blackbodies based on Re–C and TiC–C metal–carbon eutectic alloys are being investigated for use as radiance and irradiance sources for precise measurements in radiometry, photometry and radiation thermometry above the conventionally assigned values of temperatures on the ITS-90 scale. Graphite crucibles having inner diameters varying between 4 mm and 10 mm were used to prepare the metal–carbon and metal carbide–carbon eutectics; the cells were designed and manufactured at VNIIOFI, Russia using high-purity materials.The melting and solidification temperatures of the cells were measured. Their reproducibility was investigated. The radiance reproducibility of the Re–C and TiC–C fixed points was found to be from 0.01% to 0.03% at 650 nm wavelength depending on the cell. Preliminary investigations of ZrC–C fixed-point reproducibility have been carried out. The radiance of all measured cells agreed at the solidification point within 0.02%.