Dielectric and Electromagnetic Wave Absorbing Properties of Two Types of SiC Fibres with Different Compositions

The dielectric and electromagnetic properties of two types of SiC fibres with different compositions were investigated. The permittivity and electromagnetic shielding effectiveness (SE) of SiC fibre bundles were measured in 8.2-12.4 GHz by waveguide method. The reflection coefficient (RC) of unidirectional SiC fibre laminates was determined in 8-18 GHz using naval research laboratory (NRL)-arc method. Results showed that the electromagnetic wave (EMW) absorbing properties of SiC fibres were correlated with their composition, microstructure and instinct performance of electrical resistance. SiC fibres with higher content and greater size of nano-scale β-SiC showed higher permittivity, conductivity, SE and lower RC, which resulted in their better EMW absorbing ability, i.e. the lower reflection to EMW.