A steady-state high-temperature method for measuring thermal conductivity of refractory materials

Abstract

A new methodology and an instrumental setup for the thermal conductivity estimation of isotropic bulk graphite and different carbides at high temperatures are presented. The method proposed in this work is based on the direct measurement of temperature and emissivity on the top surface of a sample disc of known dimensions. Temperatures measured under steady-state thermal equilibrium are then used to estimate the thermal conductivity of the sample by making use of the inverse parameter estimation technique. Thermal conductivity values obtained in this way are then compared to the material data sheets and values found in literature. The reported work has been developed within the Research and Development framework of the SPES (Selective Production of Exotic Species) project at INFN-LNL (Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro).

Thermal and Mechanical Characterization of Carbides for High Temperature Nuclear Applications

“…Thermal conductivity (k), total hemispherical emissivity (ε) and temperature limit (T LIMIT ) can be estimated making use of experimental techniques developed at LNL in the context of the SPES project [14,15]. On the contrary, thermoelastic properties E, ν and α are usually difficult to obtain, especially if temperature-dependent values are required.…”

“…These two properties are usually unknown for the home-made materials constituting the target discs. With this in mind, a concise description of the methodologies developed at LNL for the estimation of both ε [14] and k [15] is proposed in the following. The high temperature furnace adopted to define T LIMIT is also presented as discussed.…”

“…The thermal conductivity k of the sample material can be estimated by means of the steady-state method reported in [15] and the experimental apparatus described in the previous paragraph (see Figure 4). At the basis of the method there is a consolidated electrical-thermal finite element model of the experimental apparatus that is capable of simulating both the conduction/radiation thermal problem (convection is not considered in high vacuum) and the electrical one.…”

“…In this work, a specific approach for their thermal and mechanical characterization is presented and discussed. The experimental apparatuses and techniques described in [14,15] were taken as a reference, and a novel strategy to identify a stress limit value for the structural design phase was introduced. In the future, the same methodology will be extended to new high-performance materials for ISOL applications [10][11][12].…”

Thermo-mechanical response FEM simulation of ceramic refractories undergoing severe temperature variations

“…Since refractories experience severe temperature variations during their service life the dependence of their thermal properties on temperature is of major importance. The literature on this subject is vast and numerous experimental data for refractories in terms of material specific heat capacity under constant pressure p C and thermal conductivity k [18][19][20][21] exist. In figure 2, these properties are plotted for polycrystalline alumina (Al 2 O 3 ) as functions of 1 T  where T denotes the absolute temperature.…”