Plasma sprayed Al ₂ O ₃ /FeCrAl composite coatings for electromagnetic wave absorption application

Al ₂ O ₃ /FeCrAl composite coatings were fabricated by atmosphere plasma spraying technique. Microstructure and dielectric properties in the frequency range from 8.2 to 12.4 GHz were investigated. The microstructure of composite coatings shows a uniform dispersion of metal particles with litter pores and microcracks in the composite coatings. The relaxation polarization and interfacial polarization in the coatings would contribute to enhance ε′ with rising FeCrAl content, and the associated loss could be considered as a dominating factor enhancing ε″. By calculating the microwave-absorption as a single-layer absorber, for the composite coatings with 41 wt.% FeCrAl content, the reflection loss values exceeding -10 dB are achieved in the frequency range of 9.1-10.6 GHz when the coating thickness is 1.3 mm.