Characterization of Cu-Graphene composites synthesized through pressure-less sintering for application in electrical contacts

This paper aims at development and characterization of copper metal matrix composites (MMCs) reinforced with graphene particles for application in electrical contacts. The composite specimens were synthesized using pressure-less sintering. The copper powders were mixed using ball milling process and thereafter were cold pressed in a closed mold. The powdered mix was then heated in a sintering furnace at a temperature of 900 degrees C. The composite samples were synthesized with 0.5 wt%, 1.0 wt%, 1.5 wt% and 2.0 wt% of graphene concentration. The characterizations included X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), measurement of density, hardness, tensile strength, compressive strength, electrical conductivity, thermal conductivity and wear rate. XRD and SEM indicated uniform dispersion of graphene within the Cu matrix. Elemental mapping indicated by EDS confirmed the presence of graphene with in the matrix with higher peak intensities for the specimen containing higher wt% of the reinforcement concentration. Density of the composites was found to decrease with the increase in graphene content. Lowest density (8.06 g/cc) was observed in the composite specimen containing 2.0 wt% of graphene. Hardness of the composites increased with the increase in graphene concentration. Highest hardness was exhibited by composite specimen containing 2.0 wt% graphene. Maximum tensile (145 MPa) and compressive strength (156 MPa) was obtained for composite specimen containing 0.5 wt%, beyond which the strengths showed a decreasing trend. Electrical and thermal conductivity values of 74% IACS and 398 W/Mk were obtained for composite specimen containing 0.5 wt% graphene. Wear behavior of the composite materials was found to be dependent on graphene concentration. Resistance to wear was found to increase with the concentration of graphene. Lowest volume loss was observed for composite specimen containing 2.0 wt% reinforcement.