A novel high-temperature FeSiAl/CaO-B2O3-SiO2 microwave absorption coating prepared via atmospheric plasma spraying

In this paper, CaO-B2O3-SiO2 (CBS) is utilized as matrix material of microwave coating for the first time to achieve high-performance microwave absorption under high-temperature. A series of FeSiAl (FSA)/CBS composite coatings were prepared via atmospheric plasma spraying. The impact of spraying power on the microstructure, electromagnetic properties, and high-temperature stability of as-sprayed coatings were studied. The experimental results reveal that CBS could effectively suppress the formation of the lamellar structure of FSA as the low initial melting temperature, also form unexpected Fe2SiO4 structure with FSA during the spraying process. The increase in complex permittivity of the coating is primarily attributed to enhanced coating density and the development of Fe-rich regions within the CBS matrix. Furthermore, the dense coating prevents the oxidation of FSA and exhibits high-temperature stability. Our coating of 1 mm thickness has a reflection loss below -5 dB with frequency range of 7–14.8 GHz at 500 °C.