Preparation and electromagnetic performance of coating of multiwall carbon nanotubes with iron nanogranule

A method to prepare one-dimensional nanocomposites based on coating of multiwall carbon nanotubes (MWNTs) with iron nanogranule was proposed. TEM micrographs show that the outer diameters of purified MWNTs are 13 nm. MWNTs through pyrolysis of carbonyl method can increase to 35 nm. The dynamic electromagnetic parameters of composites were measured in the 2-18 GHz range. At 2 GHz, the μ′,μ″,ε′ and ε″ of the composites are 2.64, 1.63, 12 and 2.04, respectively. These characteristic electromagnetic properties may be used for microwave absorbing material. As the reaction temperature is 180∘C, the compatibility of deposition rate and chemsorption rate is helpful in obtaining a better coating layer on MWNTs. It was also found that supercritical drying technology can eliminate surface tension and keep the structure of the one-dimensional nanocomposites.