M. Sadli

Thermodynamic temperature determinations of Co?C, Pd?C, Pt?C and Ru?C eutectic fixed-point cells

Thermodynamic temperatures during the melt and the freeze of Co?C, Pd?C, Pt?C and Ru?C metal?carbon fixed-point cells manufactured by LNE?INM/CNAM, NMIJ and NPL were determined by absolutely calibrated filter radiometers traceable to the PTB cryogenic radiometer and a radiance comparison method using an IKE LP3 radiation thermometer. The measurement uncertainties were below 400?mK at temperatures up to 2250?K. The results are in agreement within the combined uncertainties with a study on relative temperature differences of the same set of fixed-point cells. For the fixed-point cells manufactured by NPL the results are compared with a previous thermodynamic temperature measurement.

Thermodynamic temperature assignment to the point of inflection of the melting curve of high-temperature fixed points.

The thermodynamic temperature of the point of inflection of the melting transition of Re-C, Pt-C and Co-C eutectics has been determined to be 2747.84 ± 0.35 K, 2011.43 ± 0.18 K and 1597.39 ± 0.13 K, respectively, and the thermodynamic temperature of the freezing transition of Cu has been determined to be 1357.80 ± 0.08 K, where the ± symbol represents 95% coverage. These results are the best consensus estimates obtained from measurements made using various spectroradiometric primary thermometry techniques by nine different national metrology institutes. The good agreement between the institutes suggests that spectroradiometric thermometry techniques are sufficiently mature (at least in those institutes) to allow the direct realization of thermodynamic temperature above 1234 K (rather than the use of a temperature scale) and that metal-carbon eutectics can be used as high-temperature fixed points for thermodynamic temperature dissemination. The results directly support the developing mise en pratique for the definition of the kelvin to include direct measurement of thermodynamic temperature.

Uncertainty Budgets for Realization of ITS‐90 by Radiation Thermometry

Recent international comparisons [1,2] and key comparisons have shown that the realization of the International Temperature Scale of 1990 (ITS‐90) above the freezing point of silver and its dissemination is more difficult than expected. In many cases, the deviations of the local scale realizations were larger than the combined estimated uncertainties could reasonably justify. On the other hand, it must be considered that the realization of the ITS‐90 by radiation thermometry is a complex exercise involving a large number of operations with many influencing parameters. Furthermore, the key comparisons need a unified approach to the treatment of uncertainties. Consequently, a rigorous standard approach for the calculation of uncertainties is necessary. In this paper three different operational schemes have been identified for realizing the ITS‐90 by radiation thermometry. For all three schemes an analysis is presented of the baseline parameters underlying the scale realization above the freezing point of si...

HIMERT: A Pan‐European Project for the Development of Metal‐Carbon Eutectics as Temperature Standards

Metal‐carbon eutectic mixtures show much promise for high‐temperature standards applications. A research project, Novel, High temperature, Metal‐carbon Eutectic fixed points for Radiation Thermometry, Radiometry and Thermocouples (HIMERT) was accepted by the European Union (submitted under the Framework 5 Growth Programme) with a view to developing a unified European approach to these standards. The objectives of the project are to develop fixed‐point cells both for radiation thermometry/radiometry and contact thermometry calibration applications. In total three sets of cells will be developed, two for radiation thermometry (by BNM‐INM and NPL) and one for contact sensors (by BNM‐LNE) and comparisons performed of the differing crucible designs. The cells developed for radiation thermometry will be calibrated according to the ITS‐90 and measured radiometrically by a third participant (PTB). A set of cells will be transported to a laboratory external to the EU (the National Metrology Institute of Japan, NMIJ) for comparison with the cells developed there. In parallel with the experimental work a theoretical investigation of the eutectic process will be elaborated by the Universidad de Valladolid. Involvement of manufacturers of both contact sensors (Thermocoax) and IR thermometers (LAND Instruments) will ensure that the project works towards the provision of better high temperature standards for the wider measurement community. In addition, at the end of the project a discussion workshop will be held where the research team will present their findings to the high temperature user community in European industry with the aim of improving metrological standards through stimulating the uptake of metal‐carbon eutectic technology on a broad front. A description of the project is given and first results are presented.

HiTeMS: A project to solve high temperature measurement problems in industry

HiTeMS is a three-year research project involving fifteen partners, part funded by the European Metrology Research Programme. The objective of the research is to develop a suite of methods and techniques that will significantly improve the practice of industrial high temperature non-contact and contact thermometry, up to at least 2500 °C. Special emphasis is given to facilitating in-situ traceability, i.e. ensuring traceability to the International Temperature Scale of 1990 (ITS-90) directly within the industrial process. HiTeMS will do this by seeking to address common problems encountered in high temperature thermometry such as unknown emissivity and varying path transmission for non-contact thermometry and sensor characterization (including thermocouple reference function determination) and, characterizing and mitigating sensor drift (to at least 2000 °C). The project started in September 2011 and this paper focuses on the anticipated research outcomes by the time of the project conclusion in Aug 2014.

Progress report for the CCT-WG5 high temperature fixed point research plan

An overview of the progress in High Temperature Fixed Point (HTFP) research conducted under the auspices of the CCT-WG5 research plan is reported. In brief highlights are: Provisional long term stability of HTFPs has been demonstrated. Optimum construction methods for HTFPs have been established and high quality HTFPs of Co-C, Pt-C and Re-C have been constructed for thermodynamic temperature assignment. The major sources of uncertainty in the assignment of thermodynamic temperature have been identified and quantified. The status of absolute radiometric temperature measurement has been quantified through the circulation of a set of HTFPs. The measurement campaign to assign low uncertainty thermodynamic temperatures to a selected set of HTFPs will begin in mid-2012. It is envisaged that this will be complete by 2015 leading to HTFPs becoming routine reference standards for radiometry and high temperature metrology.

Fe?C eutectic fixed-point cells for contact thermometry: an investigation and comparison

Five iron?carbon (Fe?C) eutectic fixed-point cells have been constructed between NPL and LNE-Cnam to investigate the robustness and to measure the agreement of their melting temperatures. Each cell was constructed with a different selection of materials sourced by NPL and LNE-Cnam. The measured emfs at the Fe?C fixed-point temperature (~1153??C), compared between cells, agree within around 1.98??V (~90?mK), where the most important contribution to the uncertainty of each measurement is the inhomogeneity associated with the measuring Pt/Pd thermocouple. This demonstrates that these cells are suitable for use as secondary fixed-point cells in contact thermometry but the robustness of the presented cells is not found to be sufficient for maintaining their integrity during repeated cycling procedures.

Construction of high-temperature fixed-point cells for thermodynamic temperature assignment

A multi-partner project is currently being conducted within Working Group 5 (Radiation thermometry) of the CIPM Consultative Committee for Thermometry (CCT), which aims at assigning thermodynamic temperatures to a selected set of high-temperature fixed-points (HTFPs) based on metal-carbon eutectics. A work package of this project (WP2) consists in producing sets of HTFP cells to serve the final phase of the project, assignment of definitive thermodynamic temperatures (WP5). The four fixed-point types are the metal-carbon eutectic points, Re-C (2474 °C), Pt-C (1739 °C), and Co-C (1324 °C), and the Cu point (1084.62 °C). The first phase of the WP2 work treats the construction of HTFP cells, which were carried out by eight National Metrology Institutes (NMIs). The cells were constructed in accordance to instructions laid out in the WP protocol, based on years of experience of WG5 member NMIs. Cells constructed in this way should, in principle, have the required performance in terms of the realized temperature, reproducibility, and long term stability. The constructed cells were then evaluated for their performance in the second phase of the WP. The WP aims at identifying at least four cells of each of the four fixed-point types to be supplied to WP5 of the CCT-WG5 research plan for final thermodynamic temperature assignment. This paper describes the first phase of the WP2. Details of the cell construction conditions and procedures are presented.

Dissemination of thermodynamic temperature above the freezing point of silver

The mise-en-pratique for the definition of the kelvin at high temperatures will formally allow dissemination of thermodynamic temperature either directly or mediated through high-temperature fixed points (HTFPs). In this paper, these two distinct dissemination methods are evaluated, namely source-based and detector-based. This was achieved by performing two distinct dissemination trials: one based on HTFPs, the other based on absolutely calibrated radiation thermometers or filter radiometers. These trials involved six national metrology institutes in Europe in the frame of the European Metrology Research Programme joint project ‘Implementing the new kelvin’ (InK). The results have shown that both dissemination routes are possible, with similar standard uncertainties of 1–2 K, over the range 1273–2773 K, showing that, depending on the facilities available in the laboratory, it will soon be possible to disseminate thermodynamic temperatures above 1273 K to users by either of the two methods with uncertainties comparable to the current temperature scale.

Construction and Implementation of a Set of Metal‐Carbon Eutectic Fixed Points

Recent work on the implementation of metal‐carbon eutectic points in the field of radiation thermometry initiated in NMIJ [1] and continued presently among several European and international laboratories, encourages an optimistic evaluation of the potential applications of such phase transitions as temperature references in the highest part of the temperature range, above the highest fixed point available on the International Temperature Scale of 1990 (ITS‐90), the copper point (1084.62 °C). Here are presented the up‐to‐date realizations of BNM‐INM in the field. The filling of three cells was carried out and the results of these operations are described. The first plateaux obtained with the Fe‐C cell are presented. The difficulties encountered in these first steps are emphasized in order to point out the particular points that have to be taken into account during the design of the cavity cells, choice of metals, filling methods, and other experimental details.