Microstructure and thermal conduction properties of Al2O3-Ag composites

Microstructure and thermal conduction properties involving thermal diffusivity and conductivity of composite, Al2O3-Ag, were investigated. The Ag particles observed in the composites were spread sporadically throughout the composite with inclusion size increasing with Ag content, rather than forming a network of thin film foil. Thermal conductivity of the composite increased with Ag content and followed composite theory prediction with a negligible influence of interfacial contact resistance. The temperature dependence of the thermal conductivity became less pronounced with increasing Ag content reflecting the nature of electron contribution in Ag rather than the typical phonon contribution in polycrystalline Al2O3. The lower composite conductivity at higher Ag contents as compared to theoretical predictions is due primarily to the residual pore phase, associated with the cavity formation for the composite containing 10 vol.% Ag.