Dielectric and microwave absorption properties of TiO2/Al2O3 coatings and improved microwave absorption by FSS incorporation

Abstract

In this paper, TiO2/Al2O3 ceramic coatings were prepared by atmospheric plasma spraying (APS) technique. The phase composition and morphological characterizations of the synthesized TiO2/Al2O3 powders and coatings were performed by X-ray diffraction and scanning electron microscopy (SEM), respectively. The dielectric properties of these coatings were discussed in the frequency range from 8.2 to 12.4 GHz (X-band). By calculating the microwave-absorption as a single-layer absorber, their microwave absorption properties were investigated at different content and thickness in details. Furthermore, by combination of the Frequency selective surface (FSS) and ceramic coatings, a double absorption band of the reflection loss spectra had been observed. The microwave absorbing properties of coatings both in absorbing intensity and absorbing bandwidth were improved. The reflection loss values of TiO2/Al2O3 coatings exceeding −10 dB (larger than 90% absorption) can be obtained in the whole frequency range of X-band with 17 wt% TiO2 content when the coating thickness is 2.3 mm.