Pure Nickel Fixed Points for Contact Thermometry Calibrations

Gotoh, Masahiko; Todd, A. D. W.

doi:10.1007/s10765-014-1727-9

Cited by 4 publications

(4 citation statements)

References 7 publications

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“…Finally, the melting temperature of the Ni cells was evaluated as 1454.1 • C with an uncertainty of 0.9 • C (k = 2), considering the significant digit of the measured melting temperatures. This value is slightly lower than those in previously reported results [5,8]. It may be caused by contamination of the sample by unknown reasons since the freezing plateaus were much steeper, meaning higher impurities.…”

Section: Resultscontrasting

confidence: 72%

“…Therefore, it is important to use a highly reproducible phase transition, and it is generally recommended to use an easy realization process between the melting and freezing. Gotoh et al [8] proposed a transient cooling method, where solid Ni remains partially in the melt, to eliminate the Ni supercooling phenomenon. This transient method seems to have some difficulties, such as continuous monitoring and manual operation of the temperature control.…”

Section: Resultsmentioning

confidence: 99%

“…Such a deep supercooling behavior does not always happen, and the reason for this behavior cannot be explained yet. Recently, Gotoh et al [8] tried to solve the problem of deep supercooling by controlling the thickness of the solidified layer to about 1.5 mm by reducing the amount of metal charged, and re-cooling after incomplete melting to promote freezing without supercooling. This kind of partial melting followed by freezing was introduced to control excessive supercooling phenomena.…”

Section: Introductionmentioning

confidence: 99%

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Melting and freezing behavior of pure Ni cells in alumina crucibles with different internal structures

Kim¹,

Kim²

2020

Metrologia

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Two pure Ni cells for thermocouple calibration were fabricated in alumina crucibles with different internal structures to investigate their melting and freezing behaviors. One of the produced crucibles had a smooth surface, and the other was made with internal circular grooves. The melting and freezing processes of each cell were investigated in 10 melting/freezing cycles using a type B thermocouple calibrated with a standard radiation thermometer. The reproducibility of the melting point was better than that of the freezing point by a factor of more than 2, regardless of the internal shape of the crucible. The freezing temperature gradually decreased with the degree of supercooling, and the slope was observed to be about −0.08 • C. It was found that in terms of reproducibility and easiness of realization the melting point was better than the freezing point for use as a fixed temperature point. Therefore, it is proposed to use the melting point as a fixed point for thermocouple calibration. Regarding the difference in internal structure of the crucible, it was observed that a cell with circular grooves was slightly better in terms of reproducibility of melting and freezing points, but it was still unclear whether this was due to the grooves formed inside the cells, and, thus, additional research is needed. The average melting temperature and uncertainty of the Ni cells fabricated in this study was evaluated as (1454.1 ± 0.9) • C.

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Section: Resultscontrasting

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Melting and freezing behavior of pure Ni cells in alumina crucibles with different internal structures

Kim¹,

Kim²

2020

Metrologia

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“…Consequently, alumina ceramic was selected as a possible solution. It has been reported that Fe-C [9], Ni [10], Ni-Ag [11] and Pd [12] cells were successfully fabricated using alumina crucibles without breakage after successive melting and freezing cycles. Thus, Fe cells were made using alumina crucibles.…”

Section: Introductionmentioning

confidence: 99%

Phase transition behavior of pure Fe cells for thermocouple calibration

Kim¹,

Kwon²,

Kim³

2022

Metrologia

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The fixed points adopted in the ITS-90 have generally been used to calibrate contact thermometers, such as thermocouples, to get the highest accuracy. The fixed point for Pd is located at the upper limit range of the Pt/Rh noble metal thermocouple calibration. However, the high price of Pd itself restricts its wide use in calibration laboratories. To overcome this difficulty, this study develops an alternative fixed point having a close transition temperature to the Pd freezing temperature of 1554.8 °C. The alternative is pure Fe with a quoted melting temperature of 1538 °C. To make a thermometric cell, an alumina crucible was used to contain the molten liquid and it was found to be robust enough to last for more than 60 cycles of melting and freezing tests without any chemical and mechanical damage. Two cells were fabricated, and their melting and freezing behaviors were studied using type B thermocouples. By considering the advantage and disadvantages of melting and freezing, the melting temperature was selected as a thermometric transition point for the calibration of thermocouples because of its easy operational processes and acceptable uncertainty level. Using a reference thermocouple that had been calibrated versus a standard radiation thermometer, the average melting temperature of the two Fe cells was 1534.0 °C with an uncertainty of 1.2 °C (k = 2). From the studies, an Fe cell made in an alumina crucible can successfully replace the Pd fixed point.

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Nickel–Silver Monotectic in Alumina Crucible for Use with Contact Thermometry

Gotoh

Dedyulin

2017

Int J Thermophys

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Pure Nickel Fixed Points for Contact Thermometry Calibrations

Cited by 4 publications

References 7 publications

Melting and freezing behavior of pure Ni cells in alumina crucibles with different internal structures

Melting and freezing behavior of pure Ni cells in alumina crucibles with different internal structures

Phase transition behavior of pure Fe cells for thermocouple calibration

Nickel–Silver Monotectic in Alumina Crucible for Use with Contact Thermometry

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