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Sadli M.,Laboratoire Communications Of Metrologie Lne Cnam | Bloembergen P.,Japan National Institute of Advanced Industrial Science and Technology | Bloembergen P.,China Institute of Metrology | Khlevnoy B.,All Russian Research Institute for Optical and Physical Measurements VNIIOFI | And 3 more authors.
International Journal of Thermophysics | Year: 2011

For high-temperature fixed points to be accepted as temperature references, it is of prime importance that their long-term stability is demonstrated. This evaluation is part of the CCT-WG5 high-temperature research project (Machin et al. in Int. J. Thermophys. 28, 1976 2007) devoted to a comprehensive evaluation of three high-temperature fixed points: Co-C (1324 °C), Pt-C (1738 °C), and Re-C (2474 °C). The assessment of the long-term stability, as well as the robustness of the cells, is examined in the first workpackage of this project. Four cells for each of the eutectic points have been constructed by NMIJ (4 Co-C, 2 Pt-C, and 4 Re-C) and NPL (2 Pt-C), and stability tests have subsequently been performed by NMIJ (Co-C), NIM (Pt-C), and VNIIOFI (Re-C). These tests consisted of ageing one cell among the set of four, for a period of 50 h around the melting temperature. For each of the three eutectic points, before and after ageing, the aged cell was compared to one of the three cells so that any drift due to ageing could be determined. The aged Co-C, Pt-C, and Re-C cells showed no significant damage and demonstrated highly repeatable melting plateaus. In this paper, after a short description of the cells and ageing process (described more completely elsewhere (Sadli et al. in Acta Metrol. Sinica 29, 59, 2008)), the results for the three fixed points are presented and discussed. © 2011 Springer Science+Business Media, LLC. Source


Yamada Y.,Japan National Institute of Advanced Industrial Science and Technology | Anhalt K.,Physikalisch - Technische Bundesanstalt | Battuello M.,INRIM - Istituto Nazionale di Ricerca Metrologica | Bloembergen P.,China Institute of Metrology | And 6 more authors.
International Journal of Thermophysics | Year: 2015

A multi-partner project to determine the thermodynamic temperatures of a selected set of high-temperature fixed points based on metal-carbon eutectics is underway as a working group activity within the Comité International des Poids et Mesures. The investigation focuses on four fixed-point types, namely, the three metal-carbon eutectic points of Re-C (2474∘C), Pt-C (1738∘C), and Co-C (1324∘C), and the Cu point (1084.62∘C). This paper describes the construction, pre-evaluation, and screening stage of the cells prior to their thermodynamic temperature determinations. The construction of the HTFP cells was undertaken by nine national metrology institutes (NMIs) according to instructions laid out in a pre-agreed protocol that ensures production of best quality cells. Four NMIs conducted the evaluation, each for a certain fixed-point type, and screened out cells that did not meet pre-determined selection criteria while assuring sufficient variety in the sources of the cells in the final selected sets. In autumn 2012, the selected cells were successfully passed on to the final stage of the project, the thermodynamic temperature measurement, and assignment. © 2015, Springer Science+Business Media New York. Source


Khlevnoy B.B.,All Russian Research Institute for Optical and Physical Measurements VNIIOFI | Grigoryeva I.A.,All Russian Research Institute for Optical and Physical Measurements VNIIOFI
International Journal of Thermophysics | Year: 2014

The tungsten carbide–carbon peritectic (WC-C) melting transition is an attractive high-temperature fixed point with a temperature of 2747.5◦C. Earlier investigations showed high repeatability, small melting range, low sensitivity to impurities, and robustness of WC-C that makes it a prospective candidate for the highest fixed point of the temperature scale. This paper presents further study of the fixed point, namely the investigation of the long-term stability of the WC-C melting temperature. For this purpose, a new WC-C cell of the blackbody type was built using tungsten powder of 99.999 % purity. The stability of the cell was investigated during the cell aging for 50 h at the cell working temperature that tooks 140 melting/freezing cycles. The method of investigation was based on the comparison of the WC-C tested cell with a reference Re-C fixed-point cell that reduces an influence of the probable instability of a radiation thermometer. It was shown that after the aging period, the deviation of the WC-C cell melting temperature was −0.12◦Cwith an uncertainty of 0.14◦C(k=2). © 2014, Springer Science+Business Media New York. Source


Svetlichny A.,All Russian Research Institute for Optical and Physical Measurements VNIIOFI | Kravtsov V.,All Russian Research Institute for Optical and Physical Measurements VNIIOFI | Kuck S.,Physikalisch - Technische Bundesanstalt | Hofer H.,Physikalisch - Technische Bundesanstalt | Galygo A.,Republican Unitary Enterprise Belarussian State Institute of Metrology
Metrologia | Year: 2014

PTB, BelGIM and VNIIOFI conducted a supplementary comparison on the fiber optic power responsivity at 1308.9 nm and 1548.8 nm. The aim of this comparison is to examine the equivalence of the fiber optic power responsivity among participating laboratories and to provide supporting evidence for associated CMC claims in BIPM KCDB. Source


Prokhorov A.,Virial International LLC | Sapritsky V.,All Russian Research Institute for Optical and Physical Measurements VNIIOFI | Khlevnoy B.,All Russian Research Institute for Optical and Physical Measurements VNIIOFI | Gavrilov V.,All Russian Research Institute for Optical and Physical Measurements VNIIOFI
International Journal of Thermophysics | Year: 2015

Presently, absolute radiometry is the main method of thermodynamic temperature determination above the silver point. The importance of such measurements has increased, as a large international project is underway aimed at assigning thermodynamic temperatures to high-temperature fixed points (HTFPs). All participants are using filter radiometers calibrated against an absolute cryogenic radiometer which, therefore, will be the basis of the provided thermodynamic temperatures of the fixed points. However, such a unified approach may lead to systematic errors (if any) common to all participants. There are methods, providing an alternative to absolute radiometry, which allow the determination of blackbody thermodynamic temperatures using relative measurements. Alternative methods, even if they have lower accuracy than absolute radiometry, could disclose some possible unrecognized systematic errors, or, on the contrary, could confirm the results obtained using absolute radiometry and increase confidence of the thermodynamic temperature determination. One such method, known as the method of ratios (i.e., double wavelength technique), is based on measuring the ratios of fluxes emitted by a blackbody in separate spectral ranges at two temperatures. This approach has been developed at VNIIOFI, but its realization met serious technical difficulties. Modern sensors with improved sensitivity and stability, extremely reproducible HTFP blackbodies, and significant progress in computational methods and computer performance provide a new chance to realize this approach with sufficient accuracy. Another method is based on comparing the ratio of fluxes measured at two wavelengths for a high-temperature blackbody with that measured for synchrotron radiation. This article overviews possibilities of the alternative methods for determination of blackbody thermodynamic temperatures by means of relative radiometry to attract attention of the thermometry and radiometry communities to the importance of international cooperation for realization of these methods. © 2015, Springer Science+Business Media New York. Source

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