A series of metal–carbon (M–C) eutectics with robust reproducible melting phase transitions are evolving as the reference high-temperature fixed-points up to 3000 °C for radiation thermometry. The mise - en - pratique prepared for the realization and dissemination of new kelvin allows the use of set of M-C blackbody fixed-points or a combination of M-C fixed-points along with silver (Ag), gold (Au) or copper (Cu) blackbodies for the direct measurement of thermodynamic temperatures at high-temperature range. The iron–carbon (Fe–C) [1153 °C] and cobalt–carbon (Co–C) [1324 °C] fixed-point cells are the doorway to high temperature above a copper fixed-point. This paper describes the in-house development of Fe–C and Co–C eutectic graphite crucible blackbodies and their realizations by linear spectral pyrometer (LP4, 650 nm) at CSIR-NPL, National Metrology Institute (NMI) of India. The novel design and assembly approaches were employed to fabricate the blackbody crucibles with 120 o inner-well cone, 100 mm ingot length and 8 mm aperture diameter with 0.9997 emissivity and robust thermo-mechanical stability. The eutectic ingots were prepared by multiple fillings of the homogeneously ground and mixed powders with 4.2 and 2.6 weight percentage of carbon in Fe and Co, respectively. Repeatability of measured melting plateau and uncertainty of the temperature measurement for both Fe–C and Co–C cells are presented. The ITS-90 temperatures ( T 90 ) to these M-C fixed-points were assigned by a spectral radiance ratio measurement (Planck’s Law) relative to the freezing point of Ag [961.78 °C]. The T 90 temperatures thus determined for Fe–C and Co–C blackbody fixed-point cells are 1154.05 °C and 1323.93 °C with the expanded uncertainty of 0.37 °C and 0.50 °C, respectively.

中文翻译：

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用于CSIR-NPL辐射测温的Fe-C和Co-C共晶定点黑体的开发和实现

一系列具有稳定可重复熔融相变的金属-碳 (M-C) 共晶正在发展成为辐射测温的参考高温定点，最高可达 3000 °C。为实现和传播新开尔文而准备的 mise - en - pratique 允许使用一组 MC 黑体定点或 MC 定点与银 (Ag)、金 (Au) 或铜 (Cu) 的组合用于在高温范围内直接测量热力学温度的黑体。铁-碳 (Fe-C) [1153 °C] 和钴-碳 (Co-C) [1324 °C] 定点电池是通往铜定点以上高温的大门。本文描述了 Fe-C 和 Co-C 共晶石墨坩埚黑体的内部开发及其在 CSIR-NPL 下通过线性光谱高温计 (LP4, 650 nm) 的实现，印度国家计量研究所（NMI）。采用新颖的设计和组装方法来制造具有 120 o 内井锥、100 mm 锭长度和 8 mm 孔径、0.9997 发射率和强大的热机械稳定性的黑体坩埚。共晶锭是通过多次填充均匀研磨和混合的粉末而制备的，这些粉末分别含有 4.2 和 2.6 重量百分比的碳在 Fe 和 Co 中。提供了测量的熔化平台的可重复性和 Fe-C 和 Co-C 电池的温度测量的不确定性。ITS-90 温度 (T 90 ) 到这些 MC 固定点是通过光谱辐射比测量（普朗克定律）相对于银的凝固点 [961.78 °C] 分配的。由此确定的 Fe-C 和 Co-C 黑体定点电池的 T 90 温度为 1154。