Improve the electromagnetic wave absorbing properties of FeSiAl particles in the P/L/S bands by optimizing the ball milling process

FeSiAl is a soft magnetic alloy powder widely used in electromagnetic wave absorption due to its high permeability. The shape anisotropy of flaky FeSiAl is optimized to improve its permeability by breaking through the Snoek limit. This, in turn, improves the magnetic loss characteristics and optimizes its electromagnetic wave absorption performance. However, preparing flaky FeSiAl usually involves the ball-milling process, which can cause serious fragmentation due to the brittleness of the FeSiAl. Crushed slags adhere to the surface of large particles and the edges of flaky FeSiAl particles are raised like a needle, affecting their electromagnetic wave absorption performance. This work presents a method to prepare integral flaky FeSiAl particles with smooth surfaces and rounded edges to effectively suppress eddy current. These particles show high permeability and higher dielectric loss and magnetic loss in the P-L bands. At a filling rate of 70 wt%, the permeability is 4.7 at 0.30 GHz, while the maximum reflection loss of 65.0 dB at 3.48 GHz. After annealing at 800 °C, EAB5 of its absorbing specimen reaches 3.35 GHz (0.43 –3.78 GHz) at 5 mm thickness. Excellent electromagnetic wave absorbing performance in the P-band can be achieved. [Display omitted] •Highly efficient flattening of brittle FeSiAl particles was facilitated by using PTFE tank and zirconia grinding balls and a high yield rate up to 95 % was achieved.•Integral flaky FSA (FF2) particles have been obtained.•Coatings filled with FF2 and 800-FF2 were expected to possess excellent electromagnetic wave absorption performance in the P, L, and S bands.