Topological changes of vapor grown carbon fibers during heat treatment

The topological change of the surface of vapor-grown carbon fibers (VGCFs) as a function of heat treatment temperature was observed using FE-SEM, STM and AFM. The morphological change at the micrometre scale from a smooth sur face, to a rope-like structure, and to a grain-Eke structure was closely re lated with the volume change, especially due to the annular fiber form. The extent to which the micro-domain grows by heat treatment is limited by the diameter of the fiber. The appearance of a Moire pattern provided evidence for the graphitization process from turbostratic to three-dimensional grap hite. (C) 2001 Elsevier Science Ltd. All rights reserved.