Preparation and Properties of Electromagnetic Wave Absorbing and Thermally Conductive Silicone Rubber Containing ZnO@FeSiAl Powders

In this study, nanoscale ZnO particles were uniformly deposited on the surface of flake FeSiAl via a precipitation method. The as-prepared ZnO@FeSiAl composite powders were incorporated into silicone rubber to fabricate a thermally conductive and microwave-absorbing material. X-ray diffraction (XRD) analysis confirmed the successful synthesis of hexagonal wurtzite-structured ZnO. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations clearly showed that ZnO nanoparticles were evenly coated on the flake FeSiAl surfaces. X-ray photoelectron spectroscopy (XPS) verified the chemical valence states of Zn and O in ZnO, confirming the formation of stable ZnO phases. Thermal conductivity tests indicated that the thermal conductivity of the silicone rubber composites first increased and then decreased as the ZnO content increased from 20[Formula: see text]wt.% to 50[Formula: see text]wt.%. The maximum thermal conductivity of 1.03[Formula: see text]W/(m[Formula: see text]K) was achieved at a ZnO loading of 40[Formula: see text]wt.%, representing a 78.9% increase compared to the pure silicone rubber matrix [0.576[Formula: see text]W/(m[Formula: see text]K)]. Microwave absorption performance was evaluated using the coaxial transmission line method. A sample with a thickness of 2.3[Formula: see text]mm exhibited a minimum reflection loss (RL) of [Formula: see text][Formula: see text]dB at 10.36[Formula: see text]GHz, with an effective absorption bandwidth (RL [Formula: see text] 10[Formula: see text]dB) covering the entire X-band (8.2–12.4[Formula: see text]GHz), demonstrating excellent electromagnetic wave attenuation capability. This work provides a simple strategy to simultaneously enhance the thermal conductivity and microwave absorption properties of silicone rubber composites, offering a practical solution for addressing electromagnetic radiation and thermal management issues in electronic devices.