Relationship between Coefficient of Thermal Expansion and Physical Properties of Carbon Solids made from Various Cokes

Abstract

Relationship between coefficient of thermal expansion and physical properties of carbon solids made from various cokes has been investigated. The samples selected include needle-like cokes which are used commercially as the filler in the manufacture of (ultra) high power graphite electrode.Changes in the bulk density, coefficient of thermal expansion, intensity of (002) X-ray diffraction peak and pore distribution measured with mercury porosimetry for carbon solids after heat treatment at baking and graphitizing temperatures are presented. The coefficient of thermal expansion is related to the orientation of crystallites, the total pore volume and the transitional pore volume for both the calcined cokes and graphitized solids.The microstructures has been observed using a polarized light microscope. Shrinkage cracking running parallel to needle-like layer is one of the important factors governing the thermal expansion.