Abstract: Although magnetic-electric composite microwave absorbing materials can broaden the absorption bandwidth and reduce coating thickness through synergistic effects, their permeability decreases sharply with increasing temperature, which limits the practical applications of such materials over a broad temperature range. Meanwhile, the dependence of the loss mechanisms of these composite coatings on temperature remains unclear. This study develops an epoxy silicone resin-based FeCo/BaTiO₃ composite coating featuring an oriented microcapacitor network structure. The aerodynamic forces of high-speed compressed air flow and the adsorption effects on the substrate surface collectively lead to the parallel alignment of FeCo flakes in the coating. This oriented structure significantly enhances the high-frequency permeability and magnetic loss while constructing a macroscopic microcapacitor network structure that boosts dielectric loss. The incorporated BaTiO₃ not only strengthens polarization loss by improving the conductivity of dielectric layers within microcapacitor structures, but also serves as a ceramic barrier to enhance the high-temperature oxidation resistance of FeCo. This effectively suppresses the attenuation of magnetic loss at elevated temperatures and optimizes impedance matching, thereby endowing the coating with strong microwave absorption performance over a broad temperature range. A trilayered microwave-absorbing coating with a total thickness of only 1.3 mm achieves an effective absorption bandwidth of 5.53, 6.22, and 4.24 GHz at 373, 473, and 573 K, respectively.

Key words: FeCo/BaTiO₃, Parallel orientation, Microcapacitor, Microwave absorption, Wide-temperature range, Multilayer coating