The Effect of Flake Microstructure on the Preparation and Properties of Cu-Graphite Sintered Nanocomposites

A novel powder metallurgy method, based on preparation of powder mixtures of copper with 0.5, 1, 1.5, 2, 2.5, 3, and 5 wt.% of nanographite particles similar to 50 nm in size, is used to produce Cu-nanographite electrical contact materials with flake microstructure. The dispersion of graphite nanoparticles in the Cu matrix is examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Morphology, particle size, and apparent density of flake powders are investigated. Microstructure, density, electrical conductivity, and hardness are studied for green and sintered samples. The composites reinforced with lower graphite nanoparticles content (0.5 wt.%) exhibit much lower agglomeration content, while the composites reinforced with higher graphite nanoparticles content (5 wt.%) showed higher agglomeration content. It is found out that the electrical conductivity of the sintered Cu-nanographite electrical contact materials decreased from 76.92 to 68.28 IACS by graphite nanoparticle addition. The maximal (similar to 34) and minimal (similar to 20) Brinell hardness is obtained for the monolithic Cu sample and 5 wt.% graphite nanoparticle reinforced Cu electrical contact materials, respectively.