Wave Absorption Properties of Phosphate-Coated Sheet Carbonyl Iron Powder

Abstract

Using sheet carbonyl iron powder treated by ball milling and annealing as the raw material, an absorbent material was prepared using carbonyl iron powder coated with a phosphate film via phosphating in a water bath. The phase, microstructure and anti-oxidant and electromagnetic properties of the phosphate-coated carbonyl iron powder products with different phosphating times were studied. Results showed that the phosphating reaction replaces a part of the carbonyl iron powder particle surface with the phosphate film of nanometre thickness. The phosphate salt film shows an amorphous–nanocrystalline structure. The phosphate film can considerably improve the oxidation resistance of the material. The phosphating treatment improves the impedance matching performance of the materials. Among various phosphate-coated samples prepared under different phosphating times, the phosphating sample with the phosphating time of 80 s exhibits the best wave absorption effect, achieving the lowest reflectance of –24.9 dB, the corresponding frequency of 5.82 GHz and an absorption bandwidth lower than –10 dB of 5.43 GHz.