The activities carried out comprise research, development of methods and instrumentation for thermometry, hygrometry and thermal properties of materials (thermophysical, radiative, thermodynamic and chemical-physical properties), as well as studies on mathematical tools for measurements. Research contracts are activated to develop measurement methods and innovative instrumentation with international and national organisations, private enterprises and public administration. Measurement services are offered in the above quoted areas.
Experimental work has been performed in the framework of the two extensions of key comparison of CSPRTs, CCT-K2: CCT-K2.2 (with NRC and NIM, INRIM Pilot) and CCT-K2.5 (with NRC and NMIJ). A new (4 K) cryogen-free refrigerator has been put into operation. Further work for a worldwide Project driven by INRIM aimed at the solution of isotopic problems with neon triple point led to new important results, most based on INRIM-provided sealed cells. Activities in the framework of the Italy - China scientific agreement continued for the production in China of new accurate RhFe thermometers, necessary for studies below 25 K. First tests have shown encouraging results and very good stability on thermal cycling of nine prototypes. Studies have been performed on the magnetic shielding properties of a cylindrical shield intended for the development of high accuracy Cryogenic Current Comparator based on the bulk high-Tc superconductor MgB2: the results are good and the finalisation of a competitive -and patentable- new instrument promising.
2004-2006 results of the dispersion of the value of the triple point of neon due to sample-to-sample isotopic variability (9 over 16 are samples in sealed cells of INRIM production). ΔT are the temperature differences, x is the 22Ne amount fraction.
Activities for long-stem thermometers were focused on upgrading the laboratory equipment and the local comparison between working standard and national standard for the various fixed points. Measurements were performed in the framework of EUROMET Project 895. The studies on the new prototype of Temperature Amplifier continued under the EUROMET (iMERA) 772 Project. After the characterisation of the low temperature reference mercury Gas Controlled Heat Pipe (GCHP), a sodium GCHP has been filled and connected to the same helium pressure line. The two GCHPs then started to be used together for the studies related to the thermodynamic relation between the two liquid-vapour phase transition curves. The results will be used in the proposal for an alternative implementation, in the International Temperature Scale, of the temperature range between the aluminium and silver freezing points. Cooperation between INRIM and NIM (China) started with the aim of realizing a Temperature Amplifier for NIM. Activities in support of the new definition of the kelvin continued under the EUROMET 885 Project on the New Determinations of the Boltzmann Constant. The group is involved in two different and independent measurement methods: acoustic thermometry and the Doppler-effect method. For the acoustic thermometer, new capsule SPRTs have been manufactured, calibrated and mounted on the resonator. The spectroscopy method based on the Doppler effect has started to be investigated, in cooperation with Politecnico di Milano and Università di Napoli II.
A further cooperation with Università di Cassino started, for the construction of a pressure controller, based on the technologies developed at INRIM.
View of the capillary structures inside the Heat Pipes used for contact thermometry.
Research activities were focused on high temperature eutectic fixed-points. Several cells of different design were constructed for the realisation of the cobalt-carbon fixed point (Co-C, 1324 ºC). Reproducibility, stability, influence of thermal environment, dependence on melting and freezing rate and annealing time were investigated through contact and radiation thermometry measurements.
The Co-C point was then used to extend and improve the "fixed-point technique" for the realisation of radiation temperature scales approximating ITS-90. A scale from the In point (156 ºC) to the Co-C has been realised with a precision InGaAs based infrared thermometer.
An extrapolation approach was followed for an independent determination of the transition temperature of the Co-C. A value in agreement with the CCT-WG5 proposal was found. The Co-C point was also included to extend the fixed-point calibration procedure of Pt/Pd thermocouples and with the aim of avoiding troublesome and time consuming comparison with the radiation thermometer. The results, in good agreement with those previously obtained with the radiation thermometer, confirm the adequacy of both approaches as implemented at INRIM.
Graphite crucible for Co-C fixed points.
The activity is aimed at providing the traceability of surface temperature measurements. A hot plate-based reference system, operating from ambient to 350 ºC, for the calibration of contact probes was constructed. A twin system was also made available to a SIT laboratory for calibration and testing of industrial temperature probes. In co-operation with the Heat and Mass Transfer Institute (Belarus) a heat spreader based on heat pipe technology was developed and its potential application in surface thermometry was investigated. The activity on fluorescence measurement methods was focused on the investigation of fibre optic sensors to be used in the industrial and biomedical fields. New sensing phosphors were studied for in situ measurements for fuel cell applications. Fast optical detection techniques were developed to investigate the temperature-dependence of colloidal quantum nanocomposite spectral emission and lifetime and their response to oxidising and inert gases was also studied.
Structure of a heat pipe-based heat spreader (HPHS) for surface thermometry.
A humidity generator based on saturation and dilution producing water vapour concentrations between 10-7 mol/mol and 10-5 mol/mol and used for the calibration of trace moisture hygrometers was commissioned. It enabled the study of ceramic-type hygrometers for moisture measurement in natural gas. The performance of polymer-based relative humidity sensors at high temperature was investigated. In the context of a technology transfer project with a SME, a method for providing the traceability of moisture measurement in solids was developed. On this base, a reference system for calibration of conductivity-type wood moisture meters was constructed and characterised. To preserve the world's most ancient "wet" mummy, the so-called Iceman, the thermo-hygrometric conditions (low temperature in saturated air) play a crucial role. State-of-the-art measurements at relative humidity close to 99 % are thus required. In co-operation with the South-Tyrol Archaeological Museum (Bolzano) novel humidity measurement methods for the conservation cell were put in place. The results provided an insight into water vapour interaction with the corpse and its effect on long-term preservation.
Detail of a phase transition (frost to dew) on a chilled-mirror dew point hygrometer. 1. gas inlet; 2. gas outlet; 3. rhodium-coated copper mirror equipped with an embedded temperature sensor.
The evitherm Society
Following the EU Project which developed the Virtual Institute for Thermal Metrology, a Society has been constituted to continue activities and to make available to all users a website comprising a database on thermal issues -including thermophysical properties - and a portal to reach the main databases maintained by other Institutions, and to provide consultancy and expertise on thermal problems. INRIM has one of the Vice Presidents of the Society, the one assigned to Metrology.
SofTools
It includes activities concerning the production, treatment and archiving of data which are beyond metrological hardware, and on which the quality of the final values of the standards and of their comparison depend. In 2006, the advances consisted of the consolidation of an iMERA Pilot research Project driven by INRIM. Attached to these activities, are the activities in the frame IMEKO TC21 "Mathematical Tools for Measurements", having an INRIM Chairman, and the start of the preparation of the next AMCTM VIII Conference, which will be held in Paris in 2008.