Thermal conductivity of the diamond-paraffin wax composite |
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Authors: | A M Abyzov S V Kidalov F M Shakhov |
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Institution: | 1.St. Petersburg State Institute of Technology (Technical University),St. Petersburg,Russia;2.Ioffe Physical-Technical Institute,Russian Academy of Sciences,St. Petersburg,Russia |
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Abstract: | The thermal conductivity of diamond-paraffin wax composites prepared by infiltration of a hydrocarbon binder with the thermal
conductivity λ
m
= 0.2 W m−1 K−1 into a dense bed of diamond particles (λ
f
∼ 1500 W m−1 K−1) with sizes of 400 and 180 μm has been investigated. The calculations using universally accepted models considering isolated
inclusions in a matrix have demonstrated that the best agreement with the measured values of the thermal conductivity of the
composite λ = 10–12 W m−1 K−1 is achieved with the use of the differential effective medium model, the Maxwell mean field scheme gives a very underestimated
calculated value of λ, and the effective medium theory leads to a very overestimated value. An agreement between the calculation
and the experiment can be provided by constructing thermal conductivity functions. The calculation of the thermal conductivity
at the percolation threshold has shown that the experimental thermal conductivity of the composites is higher than this critical
value. It has been established that, for the composites with closely packed diamond particles (the volume fraction is ∼0.63
for a monodisperse binder), the use of the isolated particle model (Hasselman-Johnson and differential effective medium models)
for calculating the thermal conductivity is not quite correct, because the model does not take into account the percolation
component of the thermal conductivity. In particular, this holds true for the calculation of the heat conductance of diamond-matrix
interfaces in diamond-metal composites with a high thermal conductivity. |
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Keywords: | |
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