Dielectric and microwave absorption properties of low power plasma sprayed NiCrAlY/Al₂O₃ coatings

Low power plasma sprayed NiCrAlY/Al₂O₃ coatings were fabricated with dried and crushed powders. Microstructure and phase composition were tested. The dielectric and microwave absorption properties of NiCrAlY/Al₂O₃ coatings were also investigated in 8.2–12.4 GHz. Results showed that NiCrAlY presented in the form of numerous lamellas and a few particles. Both the real and imaginary part of permittivity increased with the increase of NiCrAlY content due to the enhancement of interfacial polarization and conductance loss. The reflection loss values of the coating filled with 20 wt% NiCrAlY could reach −10 dB in the frequency range of 8.7–10.8 GHz at a thickness of 1.7 mm.