Effect of Graphite and SiC Addition into Cu and SiC Particle Size Effect on Fabrication of Cu-Graphite-SiC MMC by Powder Metallurgy

Here we have reported individual and combined effect of graphite and SiC into Cu matrix during fabrication of Cu-graphite-SiC hybrid metal matrix composite by powder metallurgy. Mechanical properties of the composites are enhanced by simultaneous addition of 1, 3, 5, 10 and 15 vol. % of graphite along with 2, 5 and 10 wt. % of SiC into pure Cu, whereas electrical conductivity deteriorates. Composites are fabricated by cold compaction of composite powder mixture followed by conventional sintering in a tubular furnace at 900 degrees C for 1 h in argon atmosphere. For comparison, SiC powder size of 5 and 50 mu m are used to study the effect of SiC particle size on microstructure, mechanical and electrical properties of the composites. Optical microscopy and scanning electron microscopy reveal the homogeneous distribution of graphite and SiC in matrix and good compatibility between Cu-graphite and Cu-SiC particles. Hardness of the composites decreases with increase in graphite and increases with increase in SiC content. Composites containing fine SiC particles show higher hardness value as compared to coarse particles. Maximum Vickers hardness value of 75 is obtained for Cu-1 vol. % graphite-10 wt. % SiC composite. Electrical conductivity decreases with increase in both graphite and SiC content. Composites containing coarse SiC particles exhibit higher electrical conductivity than fine SiC.