Effects of the hot shearing of mesophase pitch on the thermal conductivity of the resulting carbon

Monolithic carbons were prepared by hot extrusion shearing of mesophase pitch under high pressure in a mould with decreasing diameter, followed by carbonization and graphitization. The influence of the shrinkage ratio(1∶1, 2∶1, 2.5∶1 and 3∶1) of the mould on the microstructure and thermal conductivity of the carbon monoliths was investigated by X-ray diffraction, scanning electron microscopy and polarized light microscopy. Results showed that mesophase carbon microspheres melted and re-combined to form fibrous and orientated domains along the axial direction under the hot extrusion shearing. A favorable microstructure for improving thermal conductivity of the carbon monoliths was obtained by the increase of the shrinkage ratios. With the increase of the ratio from 1∶1 to 3∶1, the thermal conductivity of the monoliths increased from 96.88 to 131.02W/(m · K) and 140.85 to 160.46W/(m · K) in the axial and radial directions, respectively.