Highly crystalline SiC fibers with enhanced microwave absorption properties via boron doping and electron beam irradiation oxidation curing

Polymer-derived silicon carbide (SiC) fibers are excellent structural and functional materials for extreme environments. However, the low efficiency of the curing process and the inferior stability of the amorphous SiC x O y phase have limited their large-scale preparation and widespread application. In this study, phenylboronic acid (PBA)-modified polyaluminocarbosilane (PACS) electrospun fibers were cured efficiently via an electron beam irradiation oxidation technique, and then converted into highly crystalline SiC fibers with low oxygen content by high-temperature sintering. The combination of irradiation oxidation and subsequent annealing treatment facilitated the effective, rapid, and sufficient curing of PACS fibers. Notably, boron played a significant role in inhibiting the growth of SiC grains and promoting the graphitization of free carbon. The SiC fibers obtained from PBA-modified PACS through irradiation oxidation curing exhibited superior electrical conductivity and microwave absorption performance, achieving a minimal reflection loss (RL) of −41.8 dB at 12 GHz with a thickness of 1.5 mm. This work provides an effective method for preparing SiC fibers with tunable carbon structures and enhanced microwave absorption properties, thereby paving a way for expanding their applications.