Effect of particle diameter and packing density on heating of metallic iron particles in alternating magnetic field

The heat losses originated from the electro-magnetic absorption in mechanically packed metallic iron nano- and micro-sized magnetic particles (MPs) and in magnetic epoxy-based composites with embedded MPs were studied by Calvet microcalorimetry. Nano-sized MPs with numerical average diameter 40 nm were synthesized by electrical explosion of wire method; micro-sized MPs with numerical average diameter 2 m were synthesized by flame decomposition of the iron pentacarbonyl. The specific loss power (SLP) of re-magnetization of press-packed powdered samples and epoxy composites in magnetic field 1750 A/m at 214 kHz was measured as a function of the volume fraction of MPs in the sample. The results showed up that SLP depended both on particle size and on volume fraction, which meant the significant effect of magnetic interaction among particles on the heat losses in electromagnetic absorption.