Development of pitch-based carbon-copper composites

Carbon-copper composites with varying copper to carbon ratio of 0.66-1.5 (by weight) were developed from coal-tar-pitch-derived green coke (as such or modified with natural graphite) as carbon source and electrolytic grade copper powder at different heat treatment temperatures (HTTs) of 1000-1400 A degrees C. The physical, mechanical, and electrical properties differ depending upon the HTT and also on copper to carbon ratio (Cu/C). The composites prepared at HTT of 1100 A degrees C having Cu/C ratio of 0.66 and 0.9 exhibited a high bending strength of 150 and 140 MPa, bulk density of 2.63 and 2.81 gm/cm(3), electrical resistivity of 1.6 and 0.96 m Omega cm and shore hardness of 88 and 84, respectively, in spite of well-known inadequate wettability between copper and carbon. Increasing the temperature from 1100 A degrees C for processing of the composites deteriorated the properties mainly due to the loss of copper through melting above 1100 A degrees C as revealed by X-ray, scanning electron microscopy, thermal analysis and EDAX studies.