Oxidation resistance of pitch-based carbon fibers during heat-treatment in carbon dioxide

The oxidation resistance of mesophase- and isotropic-pitch-based carbon fibers during heat treatment in CO2 atmosphere were examined and compared. The cross-sectional texture and morphology of the fibers were studied using a field emission scanning electron microscope with an acceleration voltage of 2 kV. The oxidation on the mesophase-pitch-based fibers proceeded slowly and superficially at the start of the reaction due to their well-oriented structure and fewer defects in the crystallites. However, after the induction period, the oxidation became quicker and deeper with increased holding time, resulting in increased weight loss and surface area. High CO2 flow rate resulted to more serious oxidation and larger pore sizes at various holding times.