Thermal conductivity of TiC-coated diamond/Al composites

Diamond/Al composites with TiC coating on diamond particles of 60% volume fraction were fabricated by gas pressure infiltration. The thermal conductivity of the composites with designated average particle diameters about 100 μm, 70 μm and 50 μm was investigated and compared to the Hasselman and Johnson (H–J) model and the differential effective medium (DEM) model. The results show that A356 aluminum matrix adheres on both the {100} faces and the {111} faces of diamond particles as the diamond particles are coated with TiC coating, and the TiC coating on the surface of diamond particles is slightly oxidized to form TiO₂ as the packed diamond particles are preheated in the infiltration furnace. Compared to the H–J model, the DEM model gives a closer result and it fits well with the uncoated composites. The interfacial thermal conductance for coated composites is back calculated to be 3·3 × 10⁷ W/m²/K by the DEM model, which is improved by 50% for uncoated composites. After taking the TiC interlayer with thickness of 1 μm into account, the total interfacial thermal conductance of the TiC-coated diamond/Al composite is estimated to be 2.9 × 10⁷ W/m²/K by using the concept of interfacial thermal resistance, which is very close to that derived from the DEM model.