Preparation of pitch-based carbon-copper composites for electrical applications

Carbon-copper composites were prepared from ternary systems consisting of a mixture of pitch/graphite/copper, using a binder coal-tar pitch, two types of graphite (natural and synthetic graphite) and electrolytic copper powder. Prior to the preparation of the carbon-copper composites, pitch:graphite mixtures (30:70 and 50:50 wt%) were thermally treated in order to remove pitch volatiles and improve the carbon yield. The treated mixtures were then combined with copper in different proportions (80:20, 70:30, 60:40 and 50:50 wt%) by a mechanical procedure. The resultant ternary systems were moulded (200 and 300 MPa) into prismatic specimens and carbonized to 850 degreesC. For comparative purposes, carbon composites were prepared with the treated mixtures using similar experimental conditions to those of carboncopper composites. The results show coal-tar pitch to be an excellent binder for this type of materials. The presence of copper enhances the electrical conductivity and flexural strength of the composites. However, the right choice of graphite is crucial for obtaining high-performance carbon-copper composites. (C) 2004 Elsevier Ltd. All rights reserved.