Measurement of Rh-C, Pt-C and Ru-C eutectic points by four national metrology institutes

摘要

The melting temperatures of three metal-carbon eutectics, rhodium-carbon, platinum-carbon and ruthenium-carbon, were measured by four national metrology institutes: the National Research Laboratory of Metrology (NRLM, Japan, now the National Metrology Institute of Japan, NMIJ), the National Institute of Metrology (NIM, China), the National Measurement Laboratory (NML, Australia), and the Korea Research Institute of Standards and Science (KRISS, Rep. of Korea). The same cells were measured using different radiation thermometers and different high-temperature carbon-tube furnaces by the four institutes, on their independently realized temperature scales. The results were compared to examine the performance of these high-temperature fixed points and to determine their melting and freezing temperatures on the International Temperature Scale of 1990 (ITS-90). The measured fixed-point temperatures were all within 0.4℃ of the calculated mean for each cell, and were within each laboratory's estimated uncertainties. The mean values were (1656.8±0.6)℃, (1737.4±0.3)℃ and (1953.0±0.4)℃, respectively, for the melting plateaus of the Rh-C, Pt-C and Ru-C eutectic points, with the uncertainties given for k=2.