Graphitization of carbon beads under pressure

Non-graphitizing carbon beads were heat-treated to 1300°～1900° under 5 kbar. Whereas the original beads carbonized at 1000° graphitize abruptly at 1500° ～ 1600°, the pre-heated ones demand higher temperature for their graphitization. The 1500°-pre-heated and 2100°-pre-heated graphitized above 1700°, and the 2670°-pre-heated above 1900°. In the HTT range where the graphitization occurs, the following changes in texture were observed: after the appearance of cactus-like projections, necks form between beads, needles and tiny flakes appear and optically anisotropic areas grow in size. A remarkable densification was found for the pre-heated beads in the same HTT range.