Conditions Extrêmes et Matériaux : Haute Température et Irradiation
CEMHTI - UPR3079 CNRS

utilisateur non identifié  |   Login

View CEMHTI Publication

Return to publication search...
Ask for a reprint
email :  


2010

ACLN
doi

B.Rousseau, J.Y.Rolland, L.Del Campo, D.De Sousa Meneses, P.Echegut, 'Modelling of the thermal radiative properties of oxide ceramics', Proceeding IHTC14 8-13th August Washington DC (2010) doi:10.1115/ihtc14-23218

The knowledge of the thermal radiative properties of heterogeneous materials is of crucial importance for designing efficient high temperature industrial devices such as thermal barrier coatings, solid oxide fuel cells or hot parts of nuclear reactor core. For a given temperature, multiple factors influence these properties including the chemical composition, the texture and the shape of the studied sample. By texture, one stands for the spatial organization of the scatterers (pores, grains, grain boundaries) within the host matrix and their respective size distribution. In the last decade, many efforts have been done to understand the role played by the chemical composition but the findings can be only applied to the case of homogeneous compounds (single crystal, glass, thin film) that are rarely applied for industrial purposes. For this case, freely available software can provide, for a given shape, thickness and temperature the spectral dependence of the radiative properties. For the case of ceramic material, often characterized by a multi scale texture, the role played by the texture still remains an open question as it can be shown by investigating the literature since the pioneering work of Lee and Kingery [J. Am. Ceram. Soc., 1960]. Thus, it can be experimentally demonstrated that two alumina ceramics with same shapes and thicknesses and with a similar porosities can exhibit two different optical behaviours. Is the porosity a pertinent parameter making possible the understanding of the radiative properties? To go one step further, we present recent modelling works developed at CEMHTI, Orléans, France, aiming to predict the radiative properties of this kinds of material. The development of the numerical tool is firstly based on a thorough description of both the chemistry and the texture of the studied compound. For the texture, a combination of several techniques can be used to reveal the 3D architecture (X-Ray µ-tomography, Scanning Electron Microscopy coupled with stereoscopic method,...) and to quantify the population of the scatterers (mercury porosimetry, gas or water sorption, picnometry,…), and that, according to their respective size. Then, this textural analysis conditions the use of suitable laws of propagation of the light (Geometric Optic Approximation, Effective Medium approximation...) in order to reproduce, at the local scale, the mechanism of scattering and absorption. This presentation will be focused on ceramic materials (heart of SOFC, thermal barrier coating) for which little information exist at their operating temperature [900-1600 K].