Thermal conductivity of porous structures教材.pdf

PHYSICAL REVIEW B 75, 094301 ͑2007͒
Thermal conductivity of porous structures
L. Braginsky,* V. Shklover, and G. Witz
Laboratory of Crystallography, ETH Zürich, 8093 Zürich, Switzerland
H.-P. Bossmann
Alstom (Schweiz) AG, Brown Bovery Strasse 7, 5401 Baden, Switzerland
͑Received 21 July 2006; revised manuscript received 24 December 2006; published 12 March 2007͒
Thermal conductivity of porous media is considered. The model permits regular power-series expansion of
the expression for thermal conductivity as a function of porosity. The coefficients of the expansion depend on
two-site correlation function of local thermal conductivities, which can be calculated from the microscopy
image of the structure. Thermal conductivities of some model two-dimensional structures as well as a real
porous yttria-stabilized zirconia film are calculated and discussed.
DOI: .094301 PACS number͑s͒: , , ,
I. INTRODUCTION value. Klemens5 used a thermodynamical approach to inves-
tigate heat propagation in porous solids. He shows that the
The problem of heat transport in porous solid films at- thermal conductivity of the isotropic porous media with
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tracts much attention of researchers due to their possible ap- small volume fraction of pores low porosity is nr= i 1
plication as thermal barrier coatings. First of