Oxidation of carbon fiber and its effect on mechanical properties

Carbon fibers are the main component and load carrier in many high-temperature composites. Oxidative ablation of carbon fibers is the main failure mechanism for high-temperature composites and seriously affects their mechanical properties. In this study, the oxidative ablation behavior of carbon fibers from room temperature to 900°C was systematically investigated using a thermogravimetric analyzer and in situ video detection. Carbon fiber weight loss occurred above 600°C in air. The video images showed that the carbon fiber surfaces changed color significantly, and then the fibers gradually disappeared. This shows that the carbon fibers underwent a chemical reaction, i.e., oxidative ablation. The oxidative ablation behavior of carbon fibers was also investigated by determining the strength of the carbon fibers at specific temperatures. The carbon fiber strength decreased above 400°C.