Effect of microstructure and grain size on the thermal conductivity of high-pressure-sintered diamond composites

We have studied the effect of the particle size of diamond (several microns to 500 μm) on the thermal conductivity of high-pressure-sintered diamond composites. The results demonstrate that the thermal conductivity of diamond-matrix composites prepared at 8 GPa in the presence of copper rises steeply with increasing diamond particle size, reaching a maximum, 9 W/(cm K), at a particle size of 200–250 μm. In the case of the samples prepared at 2 GPa and containing isolated diamond grains in a Cu-Ti binder, the grain size has a weaker effect on the thermal conductivity of the material, which can be accounted for by the low thermal conductivity and key microstructural features of the binder.