Improved impedance matching and microwave absorption properties of FSA/WV coatings with discrete structure

摘要

FeSiAl powder (FSA)/water-based varnish (WV) microwave-absorbing coatings with discrete structure (DMCs) were fabricated, and the effects of the discrete structure on their impedance matching and absorption performance were investigated. The electromagnetic parameters of FSA were determined in the frequency range 2-18 GHz using transmission/reflection measurements. The microwave absorption (MA) properties of the coatings were determined by measuring the reflection loss using the arch method. The normalized input impedances of the DMCs with different coatings were calculated for the investigation of impedance matching. The results showed that, compared with conventional coatings, the discrete-structure coating has superior impedance matching and delivers clearly enhanced MA performance. When the concentration of FeSiAl is 17 wt%, the absorption peak reaches —12.5 dB from —5.8 dB, and the qualified frequency bandwidth is 2.5 GHz. Furthermore, the effect of the discrete unit size and coating thickness on the impedance matching and absorption performance of the coatings were investigated.