Pitch-based carbon composites with granular reinforcements for frictional applications

Four pitches (a commercial impregnating coal-tar pitch, an ah-blown pitch and two thermally treated coal-tar pitches) and four granular carbons (graphite, anthracite, petroleum coke and foundry coke) were used to prepare carbon composites. A preliminary study of the main parameters involved in the preparation process of the carbon composites was carried out for the selection of the most suitable conditions. Mixtures with 30 wt.% of pitch and a moulding pressure of 80 MPa were selected and used for the preparation of all carbon composites. The behaviour of the resultant materials during carbonisation influenced their final properties. Composites obtained from the commercial pitch and air-blown pitch combined with anthracite and foundry coke deformed on carbonisation, presenting a high porosity and low mechanical properties. Materials obtained from the thermally treated pitches, foundry coke and anthracite were the ones with the highest compressive strength. The frictional behaviour of the materials was mainly governed by the type of granular carbon used. (C) 2000 Elsevier Science Ltd. All rights reserved.