Processing of diamond-particle-dispersed silver-matrix composites in solid–liquid co-existent state by SPS and their thermal conductivity

Diamond-particle-dispersed silver (Ag) matrix composite was fabricated in a unique fabrication method, where solid–liquid coexistent state of the powder mixture of diamond, pure Ag and pure Si was designed to create during spark plasma sintering (SPS) process. The composite is well consolidated in a temperature range between 1113 K and 1188 K and no reaction was detected by scanning electron microscopy at the interface between diamond particles and the Ag matrix. The relative packing density of the diamond–Ag composite fabricated was 95–97% in a volume fraction range of diamond between 40% and 50%. The thermal conductivity of the diamond–Ag composite containing 50 vol.% (v/o) diamond reached 717 W/mK, approximately 80% the theoretical thermal conductivity calculated by Maxwell–Eucken’s equation. This result suggests that the solid–liquid co-existent state during SPS consolidation is very effective not only for rapid densification of the composite but also for producing strong bonding between the diamond particles and the Ag matrix.