Developing Robust FeSiAl/PEEK Composites for Wide-Temperature-Range Electromagnetic Wave Absorption

Presently, researchers are placing emphasis on microwave absorption coating design while neglecting the research on materials that integrate both microwave absorption performance and mechanical properties. Here, robust FeSiAl/PEEK composites were prepared by a series process, including post ball-milling annealing, sol–gel method, and hot pressing. A detailed analysis of the electromagnetic (EM) parameters reveals the significant effects of morphology, filling ratio, and microstructure of FeSiAl on EM losses under a wide-temperature range. With 20 vol % filler loading, flaky-FeSiAl@SiO2/PEEK composite exhibits excellent performance for wide-temperature-range microwave absorption in the X-band. At room temperature, the minimal reflection loss (RLmin) reaches −28.6 dB at 10.8 GHz and the effective absorption bandwidth (EAB) is up to 3.26 GHz at 1.8 mm. As the temperature rises to 573 K, the RLmin reaches −25.8 dB at 11.2 GHz, and the EAB decreases to 2.04 GHz at a thickness of only 1.3 mm. The good performance is maintained over a wide-temperature range due to the SiO2 shell, which serves as an intermediate layer between FeSiAl and PEEK, not only improving impedance matching but also mitigating adverse eddy current losses at elevated temperatures. In addition, the SiO2 shell enhances the mechanical properties of the flaky-FeSiAl@SiO2/PEEK composite, with tensile strength reaching 84.38 MPa at 298 K, and remaining at 16.33 MPa at 573 K. Therefore, the flaky-FeSiAl@SiO2/PEEK composite emerges as a promising candidate for materials that integrate both superior microwave absorption performance and robust mechanical properties under wide-temperature-range conditions.