Evaluation and Selection of High-Temperature Fixed-Point Cells for Thermodynamic Temperature Assignment

Yamada, Yoshiro; Anhalt, K.; Battuello, M.; Bloembergen, P.; Khlevnoy, B. B.; Machin, G.; Matveyev, M.; Sadli, M.; Todd, A. D. W.; Wang, T.

doi:10.1007/s10765-015-1860-0

Cited by 25 publications

(41 citation statements)

References 4 publications

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“…Melting range and irregularity in the plateau shape, such as non-sharp entry and slow exit (run-off), are aspects that are evaluated when assessing the quality of a fixed-point cell [8].…”

Section: Discussionmentioning

confidence: 99%

Improving fixed-point cell realization by modifying furnace heater shape

Lowe

Wright

Liller³

2019

19th International Congress of Metrology (CIM2019)

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Recent changes to the SI make it possible to set up a primary temperature scale using established values for certain high-temperature fixed points. As the furnace used with the fixed points can itself have a significant impact on measurements, improving furnace temperature uniformity can help to reduce uncertainties. A thermal model was used to redesign heaters to reduce temperature gradients where the fixed-point cell is positioned in the furnace. A heater optimised for 1325 °C was compared to the standard one with a cobalt carbon high-temperature fixed-point cells, where the cell was installed in the middle, and also moved 10 mm to each end. The modified heater showed reduced melting range, improved plateau run-off and less sensitivity to fixed-point cell position. The improvements will reduce the uncertainties associated with this type of furnace.

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“…Melting range and irregularity in the plateau shape, such as non-sharp entry and slow exit (run-off), are aspects that are evaluated when assessing the quality of a fixed-point cell [8].…”

Section: Discussionmentioning

confidence: 99%

Improving fixed-point cell realization by modifying furnace heater shape

Lowe

Wright

Liller³

2019

19th International Congress of Metrology (CIM2019)

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“…6 rather clearly evidence such a situation with a flatness of the plateau that increases by increasing the melting time, i.e., by reducing the temperature setting. It is worthwhile to recall that, because of the different method used in [9] to derive the melting range, the results are not directly comparable, even if quite similar.…”

Section: Melting Ranges Of the Inrim Co-c Cellsmentioning

confidence: 95%

“…Measurements with the "old" Cu2 took place at INRIM in Nov-Dec 2011 during the evaluation process of the HTFP Research Plan [9]. The "new" Cu4 was investigated in June 2012 during a run of supplementary measurements.…”

Section: Measurements With the Cu Cellsmentioning

confidence: 99%

“…The old CoC3 was evaluated at LNE, and its transition temperature was 165 mK lower than that of the LNE cell, i.e., the highest of the six cells that took part in the comparison [9] (see Table 4). Figure 4 shows the typical shapes of melting curves with the two Co-C cells with different furnaces.…”

Section: Melting Temperature Of the Inrim Co-c Cellsmentioning

confidence: 99%

“…In [9] the melting ranges of eutectic fixed points were evaluated by multiplying the slope of the tangent at the inflection point by the duration of the melting plateau, the latter being defined as the time between the two points of maximum curvature near the beginning and the end of the melting process.…”

Section: Melting Ranges Of the Inrim Co-c Cellsmentioning

confidence: 99%

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Influence of the Cavity Length on the Behavior of Hybrid Fixed-Point Cells Constructed at INRIM

2014

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Hybrid cells with double carbon/carbon sheets are used at the Istituto Nazionale di Ricerca Metrologica (INRIM) for the realization of both pure metal fixed points and high-temperature metal-carbon eutectic points. Cells for the Cu and Co-C fixed points have been prepared to be used in the high-temperature fixed-point project of the Comité Consultatif de Thermométrie. The results of the evaluation processes were not completely satisfactory for the INRIM cells because of their low transition temperatures with respect to the best cells, and of a rather large melting range for the Co-C cell. A new design of the cells was devised, and considerable improvements were achieved with respect to the transition temperature, and the plateau shape and duration. As for the Cu point, the duration of the freezing plateaux increased by more than 50 % and the freezing temperature increased by 18 mK. As for the Co-C point, the melting temperature, expressed in terms of the point of inflection of the melting curve, increased by about 70 mK. The melting range of the plateaux, expressed as a difference (T liquidus − T solid ) was reduced from about 180 mK to about 130 mK, with melting times (t liquidus − t solid ) increased by about 50 %, as a consequence of an improvement of flatness and run-off of the plateaux.

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