Carbon fibers with eddy current loss characteristics exhibit different microwave absorption properties in different graphitization states

The precursor was prepared by electrospinning method with Polyvinyl alcohol (PVA) as a raw material, and carbon fibers were obtained through pre-oxidation and carbonization process. The results of the experimental confirmed that different graphitization states can cause changes in microwave absorption characteristics. When the carbonization temperature was 650 °C, carbon fibers showed excellent microwave absorption characteristics with a minimum reflection loss value of −45.2 dB, under the effect of dielectric loss. When the carbonization temperature was 850 °C, carbon fibers showed excellent microwave absorption characteristics with a minimum reflection loss value of −44.4 dB, under the combined effect of eddy current loss and dielectric loss. The interface isomerization of amorphous carbon and graphitized carbon and the defects in amorphous carbon and graphitized carbon can be regarded as polarization centers, which leaded to dielectric loss. Moreover, in terms of structure, the skin effect occurred in the bridged carbon fibers which can cause eddy current loss.