Tuning microstructures of polyacrylonitrile-based carbon fibers by catalytic influence of boron for enhancement of mechanical properties and oxidation resistance

Boron catalytic graphitization of carbon fibers (CFs) is an effective methodology for reducing energy costs with the enhancement of tensile and oxidation resistance properties by re-constructing the crystal structure of CFs. Herein, a microwave plasma graphitization system for boron catalytic graphitization was devised. The effect of boron on microstructure and properties of CFs during boron catalytic graphitization process was investigated and analyzed. The mechanism of boron doping in different graphitization times was proposed. Furthermore, the results show that the tensile properties and oxidation resistance of CFs are improved and directly related to the microstructure of CFs, which depends on the different boron catalytic graphitization stages. This work provides the effect of boron on microstructure and properties of CFs during microwave plasma catalytic graphitization in different graphitization times and has important implications for deeply understanding the boron catalytic graphitization process which is beneficial for the preparation of CFs with excellent performance. [Display omitted] •Highly efficient graphitization of carbon fibers was fulfilled by the novel method using microwave plasma.•The mechanism of boron doping was proposed for deeply understanding the boron catalytic graphitization process.•The linkage between properties and microstructures of carbon fibers was established.