Effect of Particle Size and Shape on Properties of Copper – Graphite Composites

The present work aims to study the effect of particles shape and size of copper powder on physical, mechanical properties and wear resistance of copper-13vol%graphite composites prepared by powder metallurgy technique.Spherical and dendritic copper powder particles were used as a matrix besides a mixture of both shapes with three particle size ranges [(25>),(38-45),(53-63)]m. 13vol%graphite powder with a grain size of(63 (≤ was added as reinforcement. All powder mixtures were mixed mechanically for 2 hours. The mixed powders were cold pressed uniaxially at (700Mpa) for 30seconds and sintered at (900 oC) for one hour. The results showed that the relative density, both electrical and thermal conductivities and compressive strength of dendritic copper composites are higher than those of spherical copper composites, for example, the maximum values for both electrical and thermal conductivities for dendritic copper (53-63)m+13vol%graphite composite were 36.01 (.m)-1, 295.55 W/m.oK respectively, while wear rate of dendritic copper composites was lower than that of spherical copper composites where the minimum value for dendritic copper composites was (1.068×10-9 g/cm) for dendritic copper (53-63)m+13vol%graphite composite. It was found through the results of the present work that relative density, hardness and compressive strength increases with decreasing copper particle size. On the other hand an improvement in wear resistance was found on decreasing the particle size.