Grinding speed dependence of microstructure, conductivity, and microwave electromagnetic and absorbing characteristics of the flaked Fe particles

Flake-like Fe particles with controllable size and structures were achieved by modulating only the grinding speed; evidence provided by x-ray diffraction, scanning electron microscopy, resistivity measurement system, and vector network analyzer disclosed the conductivity; and microwave electromagnetic (EM) and absorbing characteristics of the resultant products strongly depended on their morphology and structure. As grinding speed (V) increases from 0 to 250 revolutions per minute (rpm), the crystalline size decreases; meanwhile, both internal strain and diameter/thickness ratio increase and the conductivity reaches the maximal value at V = 140 rpm because of the improvement of the surface conductivity. Thin flake-like Fe particles facilely obtained at high grinding speed present higher values of the permittivity and permeability than spherical particles, which are ascribed to the multiple polarizations and the natural resonance. Thus, the aforementioned products with high permeability and low cost may be promising candidates for EM compatibility materials.