Adiabatic Calorimetry Approach to Assess Thermal Influences on the Indium Melting Point

Abstract

Within the framework of the Euramet project 732, LCM/LNE-CNAM has recently proposed a new device to investigate the melting point of indium (156.5985 • C) by the way of an adiabatic calorimetry approach. An apparatus based on a cell-within-cell configuration was developed and experimentally tested. First results highlighted parasitic heat flows due to the geometrical characteristics of the cell, disturbing significantly the isothermal condition within the calorimeter. Such thermal effects were also clearly identified with a specific numerical model developed for this purpose. Considering the remarkable agreement between the model and relevant experiments, an optimization step has been carried out to design a suitable cell geometry. A new enhanced cell was subsequently fabricated and arranged within the calorimeter (indium load of 122.32 g). The purpose of this article is to introduce the thermal behavior of such a highly effective apparatus, while presenting some series of measurements; on the one hand, the melting point of indium under adiabatic conditions is studied, and on the other hand, the so-called continuous heat flow method under isothermal conditions is worked out. The obtained results are discussed and analyzed according to the impurity concentrations into the ingot (sum of individual estimate method).

Ultra-Responsive MEMS Sensing Chip for Differential Thermal Analysis (DTA)

“…The peak value is ~190 mV (corresponding to a temperature change of 6.8 °C), which validates the ultra-high responsivity of the MEMS thermopile sensors. The measured melting point is 156.0 °C at a heating rate of 1 °C/s and 157.6 °C at a heating rate of 100 °C/s, which shows a thermal lag of within 1 °C compared to the reported value of 156.6 °C [ 24 ]. Figure 5 b shows detailed images of the indium melting and resolidification processes during the DTA measurement.…”

Développement d’une nouvelle génération de points fixes de température entre 83 K et 950 K

“…Les extrapolations réalisées pour déterminer la température de liquidus du métal idéalement pur à partir des tracés en 1/f obtenus en mode adiabatique sont sensiblement plus fiables et avec des incertitudes plus faibles que celles issues des données obtenues à flux permanent [12,13].…”

“…La détection des densités de flux, bien que locales dans ces travaux, a montré son efficacité pour la détermination des points d'entrée et de sortie d'un plateau de fusion [12][13][14] (respectivement les points de solidus et de liquidus). En conséquence, il nous est possible de proposer une nouvelle approche pour la définition de la température de changement d'état, à partir d'un formalisme reposant sur les deux premiers principes de la thermodynamique [15,16].…”