木炭の多相黒鉛化過程

抄録

Charcoal has been known to show mdlti-phase graphitization in a wide range of temperature of heat treatment. In the present work, a charcoal was heat-treated at various temperatures of 1500-3400°C for 15 min in an Acheson-type furnace and its composite profile of (002) diffraction line was separated into component profiles. The composite profile of the charcoal was concluded to consist of three component profiles; a broad band with a larger c₀ -spacing than 6 .86Å, and two sharp peaks with the c0 -spacings of ca . 6.86 and ca. 6.73Å, respectively. Two components corresponded to two sharp peaks were assumed to have turbostratic and graphitic structures and so named the components T and G, respectively . However, the structure corresponded to the broad band (named the component B) was not known. At low temperature of heat treatment, the component B was major and its structure seemed to change to that of the component T gradually with the increase in temperature. Above 2400°C, the graphitic component G became the major one.
By comparison of the present results to the results on other hard carbons and on the soft carbons under high pressure, the structure of hard carbon might be assumed that small particles of anisotropic structure are dispersed in a matrix of isotropic structure. At high temperature, anisotropic thermal expansion of the small particles may seem to be constraint by the isotropic matrix so that stress may concentrate at the small particles and abrupt structural change to graphitic structure (multi-phase graphitization) may occur.