Abstract:
On the basis of experimental data on thermal conduction and sound velocity in composites obtained by sintering detonation nanodiamonds with the crystallite size of 4–5 nm and diamond micropowders with a grain size of about 10 $\mu$m at a high pressure (5–7 GPa) and high temperature (1200–1800$^\circ$C), mechanisms of heat transfer in such structures are suggested. These mechanisms are shown to be different in composites of micro- and nanoparticles. In composites of micrometer particles, the conventional macroscopic mechanism of phonon propagation is active. In composites with a grain size of a few nanometers, the main contribution comes from thermal resistance on grain boundaries.
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