Influence of filler type on the performance and microstructure of a carbon/graphite material

Carbon/graphite material was prepared by subjecting a mixture of coal-tar pitch binder and a relevant filler to uniaxial compression at 150 MPa for 10 min, followed by calcination at 1 300 °C for 1 h, and graphitization at 2 300 °C in an induction furnace. Four fillers, carbon black (CB), petroleum-coke powder, needle-coke powder, and natural graphite powder (NG), were used. The effect of filler type on the performance and microstructure of the material was investigated. Results reveal that the CB-based material has excellent flexural and compressive strength, with the highest values of 88.0 and 173.2 MPa, respectively, but poor thermal and electrical conductivity. The thermal conductivity of the NG-based material has the highest value of 278 W/m·K, but the flexural and compressive strength are limited to 51.1 and 90.2 MPa, respectively. Microstructural analysis showed that the NG-based material has the largest crystallite size, as well as the most perfect orientation of graphite layers.