Effect of Boron Addition on the Thermal Conductivity of Cu/Diamond Composites Fabricated by SPS

Abstract

Diamond-particle-dispersed-copper (Cu) matrix composites were fabricated by spark plasma sintering (SPS) process from the mixture of diamond particles, pure–Cu and boron (B) powders. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated at a temperature of 1173 K for 600 s by spark plasma sintering (SPS) process. No reaction at the interface between the diamond particle and the Cu matrix was observed by scanning electron microscopy and X-ray diffraction analysis for the composites fabricated under the sintering condition employed in the present study. The relative packing density of the diamond particle dispersed Cu matrix composites with B addition was 3.5～6.1 % higher than that without B addition. The thermal conductivity of the Cu/diamond composite drastically increased with B addition. The thermal conductivity of (Cu–B)–50 vol% diamond composites was 594～689 W/mK in a volume fraction range of B between 1.8 and 13.8 vol% in Cu matrix. Numerous transgranular fractures of diamond particles were observed on the bending fracture surface of diamond particle dispersed Cu matrix composites with B addition, indicating strong bonding between the diamond particle and the Cu matrix in the composite.