Mesophase pitch-based carbon fibers (MPCF) possess excellent properties, such as high modulus and high thermal conductivity, making them key strategic materials for national defense security and advanced equipment development. However, their oxidation behavior in high-temperature aerobic environments remains poorly understood. This study investigates the oxidation behaviors and the evolution of mechanical and thermal properties of two types of MPCF, namely split-structured (CF-A) and round-structured (CF-B), in both carbonized (1600 ℃) and graphitized (3000 ℃) states. The results show that CF-A-1600 exhibits preferential core oxidation during the 600 ℃ oxidation process, leading to a tensile strength retention of only 34.93%, which is lower than that of CF-B-1600 (51.79%). Conversely, the CF-A-3000 achieves tensile strength retention of 79.64% and thermal conductivity retention of 94.36%, respectively, higher than those of CF-B-3000 (77.46% and 90.93%). For carbonized MPCF, the oxidation behavior is dominated by diffusion-controlled reactions, where structural morphology plays a decisive role, and CF-B fibers exhibit superior oxidation resistance. For graphitized MPCF, oxidation behavior is governed by chemical-controlled reactions, in which intrinsic crystallite activity becomes dominant. For comparison, CF-A fibers show superior performance due to their better-developed crystallites and consequently higher oxidation activation energy. This study reveals the coupled mechanism between structural morphology and intrinsic crystallite activity of MPCF, providing a theoretical reference for reliability assessment and material optimization design of MPCF and their composites in extreme thermal service conditions.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |