Characteristics of silicon carbide fiber-reinforced composite for microwave absorbing structures

A microwave-absorbing structure is a multifunctional composite composed of lossy materials, to obtain optimal electromagnetic properties combined with structural load-bearing capability. Microwave energy-loss properties can be obtained by modifying the matrix with a lossy filler, or by using a reinforcing fiber with lossy characteristics. The silicon carbide fiber is a conventional semi-conductive fiber that can cause microwave-energy loss, and can comprise a composite material by using a general resin system without lossy additives. This study investigated the mechanical and electromagnetic properties of SiC/epoxy composites, and the performance of microwave-absorbing structures composed of the SiC/epoxy. The fiber volume fraction and tensile properties of a SiC/epoxy composite cured at 6.0 bar were measured. Electromagnetic properties of SiC/epoxy composites cured at different pressures from 7.0 bar to 3.5 bar were measured in addition. Single-slab and multi-slab absorbers were fabricated, and their performance was evaluated. The -10-dB bandwidth and the minimum return loss of the four-slab absorber were 3.4 GHz and -31.0 dB, respectively. An analysis of the SiC/epoxy-composite characteristics indicated that it had excellent workability and mechanical-property advantages, although the performance of the SiC/epoxy microwave absorber was ordinary.