Preparation and microwave absorbing properties of hollow carbon fibers

Hollow carbon fibers were prepared by thermo-oxidative stabilization in air and carbonization in nitrogen of polyacrylonitrile hollow fibers as precursor. The microstructure and electromagnetic parameters of the resultant hollow carbon fibers were studied by SEM, IR and voter network analysis. The reflectivity was simulated using RAMCAD software. The results show that the hollow carbon fibers have an asymmetric structure with a lot of irregular micropores. The real and imaginary parts of the complex permittivity of composites of the hollow carbon fibers and paraffin are 39 and 54 at 2 GHz, respectively. The calculated reflectivity of composites with the thickness of 1 min is about -7.5 dB at 13.52 GHz and the bandwidth under -5 dB is about 6 GHz. The hollow carbon fibers are proved to be a light conductive radar absorbing materials.