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Effects of Particle Size of Copper on the Electrical Property and Hardness of Copper/Graphite/Carbon Fiber/Phenolic Resin Composites

Composites made from phenolic resin are filled with conductive filler mixtures containing copper powders, natural graphite powders and carbon fibers. They are fabricated by compression molding technique. The density, electrical conductivity and hardness of composite are analyzed to determine the influence of copper particle size on the physical, electrical and mechanical properties of composite. It is found that there is a marked dependence of the electrical conductivity and hardness on copper particle size. The hardness decreases with the decreasing of copper particle size. However the electrical conductivity increases with the decreasing of copper particle size. The decreasing of copper particle size from 75 µm to 48 µm promotes a considerable increase in electrical conductivity by about 427%. The increased continuous conductive metal networks could be the main reason for the increasing of electrical conductivity as copper particle size decreases. The results also show that composites containing copper particles of different sizes have the nearly same density.