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FP5

HIPERCOAT Informe resumido

Project ID: G5RD-CT-2001-00573
Financiado con arreglo a: FP5-GROWTH
País: France

Models for thermal conductivity

I. CALCULATION OF THE THERMAL CONDUCTIVITY OF COMPLEX OXIDES
A method, based on a NEMD (Non Equilibrium Molecular Dynamics) technique, has been developed for calculating the thermal conductivity of complex oxides. Starting from the nature of atoms, the crystallographic structure and the inter-atomic potentials, it gives the thermal conductivity of complex oxides as a function of temperature. It is important to note that no adjustable parameter has been introduced in the inter-atomic potentials adopted (from published data).

After validating the method on the yttria-zirconia system, and evaluating the possibilities and limits of this approach, the code has been run to investigate various oxide systems, some of them prospective (ternary zirconias, perovskites for example). It is used currently at ONERA within the framework of a project aiming at developing new ceramics for thermal barrier coatings.
Contact: remy.mevrel@onera.fr or mathieu.fevre@onera.fr

II. CALCULATION OF THE THERMAL CONDUCTIVITY OF A MULTIPHASE SOLID FROM A 2D OR 3D REPRESENTATION OF ITS STRUCTURE.
A numerical method has been developed to calculate the effective thermal conductivity of heterogeneous materials directly from representations of the material. It is based on a FDM procedure applied on images (2D) or volumes (3D) representing the material. In this way, the real microstructure of the material is taken into account, thus avoiding any simplifying meshing. The effective thermal conductivity can be calculated from these representations in which each pixel (or voxel) is attributed the properties of the phase it corresponds to.

A particular attention has been paid on the choice of the numerical method adopted and on the development of an original method for compacting the data so that large domains can be handled in an efficient way on common computers. For example, the 3D calculation of the thermal conductivity tensor has been performed on a 100 Mvoxels domain representing an EBPVD coating in 5 hours CPU times on a computer equipped with 2 Go RAM.

It is to be noted that this code can be exploited for calculating the thermal conductivity of any heterogeneous material provided a 3D representation is available and the thermal conductivity of the individual phases are known.
Contact: remy.mevrel@onera.fr or jean-marc.dorvaux@onera.fr

Información relacionada

Contacto

Remy MEVREL, (Dr.)
Tel.: +33-1-46734499
Fax: +33-1-46734164
Correo electrónico
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