Volume expansion of glass-like carbon upon high temperature heat treatment

摘要

The glass-like carbon made from the carbonization of thermosetting resin such as phenolic resin or polyfurfulyl alcohol resin (furan resin) is a typical non-graphitized carbon. The glass-like carbon appears to be homogeneous and hard, and its fractural surface has luster-like glass. When the glass-like carbon is heated at high temperature and cooled back to the original temperature,the volume increases a little with increasing heat treatment temperature (HTT) and the density decreases as the result. This volume expansion is an interesting phenomenon. A structural model of glass-like carbon with high heat treatment has been proposed by Jenkinset al. [1] or Shiraishi [2]. The former modelis characterized by a network structure of tangled graphite ribbon-like molecules with micropores or spaces formed by the imperfect packing of the ribbons. This model is based on wound and entangled arrangements of stacked carbon layer planes as observed by transmission electron microscopy. The model of Shiraishi ischaracterized by a closed cell structure resembling a wlld cell wall. These models suggest the volume expansion of glass-like carbon is caused by enlargement of micropores or spaces in the structure. When the carbon materials are heat-treated at high temperature, ordering of the carbon layer planes proceeds accompanied by layer growth and decrease of the interlayer spacing. Our X-ray data for glass-like carbon, however, indicates that the interlayer spacing broadens rather than narrows during HTT. Here we describe whether the broadening of interlayer spacing takes part of in the volume expansion of the glass-like carbon.