Bilateral Comparison Between NPL and INMETRO Using a High-Temperature Fixed Point of Unknown Temperature

Machin, G.; Teixeira, R. N.; Lu, X.; Lowe, D.

doi:10.1007/s10765-014-1749-3

Cited by 4 publications

(6 citation statements)

References 12 publications

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“…The study reported here extends the work reported in [11] to the cobalt carbon HTFP Five Co-C cells were constructed from graphite of the same grade and batch, with high purity Co from the same batch. Two of the cells were doped with differing quantities of Fe and two with differing quantities of Pt.…”

Section: Introductionsupporting

confidence: 68%

“…During melting, however, the sign of V is reversed and so, to some extent, the two terms cancel [18]. For high purity eutectic systems the degree of cancellation is almost complete and only a small dependence has ever been observed [11,19]. However, since the constants are likely to be different in doped HTFPs from the pure systems it is necessary to check if there are differences that might indicate how the HTFP has been doped.…”

Section: Measurements Of the Htfpsmentioning

confidence: 99%

“…To obviate this, a study was performed [9][10][11] to investigate what was the effect of doping a pure HTFP (in that study Ni-C) with relatively large levels of dopants. Both the effect on the actual melting temperature and the metrological quality of the point of inflection (by convention, taken as the melt temperature) was studied.…”

Section: Introductionmentioning

confidence: 99%

“…Both the effect on the actual melting temperature and the metrological quality of the point of inflection (by convention, taken as the melt temperature) was studied. It was shown [11] through a bilateral comparison between NPL and INMETRO (Brazil) that doped HTFPs appear stable and could serve as blind high temperature comparison artefacts.…”

Section: Introductionmentioning

confidence: 99%

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Stability of cobalt–carbon high temperature fixed points doped with iron and platinum

et al. 2015

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High temperature fixed points (HTFPs) are stable and repeatable and make comparison of temperature scales possible at a level of uncertainty not previously possible. However, they potentially lack objectivity if the fixed-point temperature is known. Five HTFPs were constructed, one pure Co-C, two Co-C doped with Fe and two Co-C doped with Pt of differing concentrations. The candidate dopants were identified through thermochemical modelling as likely to give maximum temperature shift with minimum increase in melting range. The temperature differences of the doped systems from the pure system were determined and it was found that the addition of Fe depressed the melting temperature and the addition of Pt elevated the melting temperature, qualitatively in line with the thermochemical modelling. The higher concentration doped HTFPs were then aged for approximately 100 h with continuous melting-freezing cycles and the difference to the undoped Co-C HTFP remeasured. These differences were found to agree with those of the unaged results within the measurement uncertainties, confirming artefact stability. It is clear that the doping of HTFPs is a powerful way of constructing stable and reliable high temperature scale comparison artefacts of unknown temperature.

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Section: Introductionsupporting

confidence: 68%

Section: Measurements Of the Htfpsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stability of cobalt–carbon high temperature fixed points doped with iron and platinum

et al. 2015

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“…However, as the temperatures of the HTFPs become better known the credibility of the comparison has been compromised because the temperatures are known a priori. To obviate this, some studies have been performed [13][14][15][16] to investigate the effect of doping nominally pure binary HTFP of Ni-C and Co-C with relatively large levels of dopants, to create a dilute ternary alloy.…”

Section: Introductionmentioning

confidence: 99%

Investigation of ternary and quaternary high-temperature fixed-point cells, based on platinum–carbon-X, as blind comparison artefacts

Wei

Machin

Bloembergen

et al. 2016

Meas. Sci. Technol.

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Extensive studies of platinum-carbon eutectic alloy based high temperature fixed point cells have shown that this alloy has extremely good metrological potential as a temperature reference. However, it's possible adoption as an accepted reference standard means that its eutectic temperature value will soon be agreed with an uncertainty less than most radiation thermometry scales at that temperature. Thus it will lack credibility if used as a future scale comparison artefact. To avoid this, the fixed-point cell can be deliberately doped with an impurity to change its transition temperature by an amount sufficient to test the accuracy of the scales of the institutes, involved in the comparison. In this study dopants of palladium and iridium were added to platinum-carbon to produce ternary alloy and quaternary alloy fixed-point cells. The stability of these artefacts was demonstrated and the fixed-point cells were used to compare the ITS-90 scales of NIM and NPL. It was found that the fixed point temperatures could be changed by an appreciable amount while retaining the stability and repeatability required for comparison artefacts.

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Long-Term Stability Evaluation of a Sn-Doped Ni–C Eutectic Cell Suitable for Radiation Thermometry

Teixeira¹,

Machin

2017

Int J Thermophys

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Bilateral Comparison Between NPL and INMETRO Using a High-Temperature Fixed Point of Unknown Temperature

Cited by 4 publications

References 12 publications

Stability of cobalt–carbon high temperature fixed points doped with iron and platinum

Stability of cobalt–carbon high temperature fixed points doped with iron and platinum

Investigation of ternary and quaternary high-temperature fixed-point cells, based on platinum–carbon-X, as blind comparison artefacts

Long-Term Stability Evaluation of a Sn-Doped Ni–C Eutectic Cell Suitable for Radiation Thermometry

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