SPS 成形したAg/ ダイヤモンド複合材料の熱物性に及ぼすダイヤモンドのバイモーダルな粒度分布の影響

概要

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Diamond-particle-dispersed-silver (Ag) matrix composites were fabricated in solid-liquid co-existent state by Spark Plasma Sintering (SPS) process from the mixture of diamond powders, Ag powders and Si powders. As the diamond powders, two kind of powders, monomodal diamond powders of 310 µm in diameter and a bimodal diamond powder mixture of 310 µm and 34.8 µm in diameter, were used. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated by heating at a temperature range between 1113 K and 1188 K for 0.45 ks during SPS process. No reaction at the interface between the diamond particle and the Ag matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. Although the relative packing density of the monomodal composite decreased from 97.4 % to 93.4 % with increasing diamond volume fraction between 50 % and 60 %, that of the bimodal composite was higher than 97 % in a diamond volume fraction range up to 65 %. The thermal conductivity of the bimodal composite was higher than that of the monomodal composite in a diamond volume fraction range between 55 % and 65 %. The coefficient of thermal expansion of the composites falls in the upper line of Kerners model, indicating strong bonding between the diamond particle and the Al matrix in the composite.