Abstract: PAN/SiO₂ coaxial fibers were prepared firstly by coaxial electrospinning using PAN as the core and SiO₂ sol as shell, and then C/SiO₂ coaxial fibers were obtained with an outer diameter of 1μm after oxidation and pyrolysis of the eletrospun fibers. The structure and cross-section morphologies of the C/SiO₂ coaxial fibers were investigated by FTIR, XRD and SEM. The results show that SiO₂ coating with thickness of about 20nm is successfully prepared on the carbon fibers. Radar absorbing properties of the C/SiO₂ coaxial fibers are studied by voter network analyzer. Compared with uncoated carbon fibers, both the real part and the imaginary part of their permittivity decrease when the fiber mass fraction is 20%. The reflectivity is simulated using RAMCAD software which shows that the 3mmthick composites has an absorbing bandwidth of 3.3GHz below -10dB in the frequency range of 2-18GHz, and the lowest reflectivity is -17dB at 12GHz. DTA-TG analysis also indicates an increase in oxidation resistance of the coaxial fibers.

Key words: coaxial fibers, coaxial electrospinning, SiO₂ coating, radarabsorbing material