Preparation and microwave absorbency of Fe/epoxy and FeNi3/epoxy composites

The focus of this study was placed on the lightness of microwave absorbing effective metal/epoxy composites. For such a focus, high aspect ratio of flake iron powder and high absorbing FeNi3 were prepared. The iron powder particle size was reduced significantly through wet milling, comparing to dry milling. The FeNi3 alloy powders were synthesized by mechanical alloying (MA); then, the particle size was reduced through wet milling. The iron powder and FeNi3 alloy were characterized by scanning electron microscopy (SEM) and X-ray diffraction. SEM of the metal particles showed the flake and small structure by wet milling. The microwave absorbing effectiveness of metal/epoxy composite was affected by the structure, loading and dispersion of metal materials. The polyvinylpyrrolidone (PVP) plays an important role in suspending metal powders in wet milling to reduce powder size. Besides, the PVP will be a coupling agent in inhibiting the aggregation and enhancing the interfacial interaction between metal and epoxy. Results suggested that after the above manufacturing process, the microwave absorbency was enhanced substantially. Composite films of Fe/epoxy and FeNi3/epoxy 1.6 mm in thickness possessed a microwave absorbency above 10 dB at 9.2–15.2 GHz and 13.1–16.2 GHz, respectively.

► Mechanical alloying was utilized to manufacture FeNi3.
► Using wet milling with PVP reduced metal particle size effectively.
► Iron powder/Epoxy possesses an electromagnetic absorbency over 10 dB at 9.2–15.2 GHz.
► FeNi3/Epoxy possesses an electromagnetic absorbency over 10 dB at 13–16.6 GHz.
► The microwave absorbency was enhanced after the optical manufacturing process.