Microwave absorbing paints made of magnetite (nano-Fe3O4) coated carbon fibers (MCCFs) play an important role in wireless data communication, local area network, satellite television, heating system, vehicles stealthing and so on. In this study production of MCCFs composites using electrophoretic deposition (EPD) technique has been investigated. For this purpose, the Fe3O4 nanoparticles with an average size of 50 nm were synthesized by reduction of Fe (III)-tri-ethanolamine in an aqueous alkaline solution and then a uniform and compact Fe3O4 thin-film was coated on the surface of nitric acid treated carbon fiber by EPD method. The crystal structure, morphology and particle size distribution of the powders and composites were examined using the X-ray diffraction (XRD), scanning electron microscopy (SEM) and dynamic light scattering (DLS) techniques, respectively. The magnetic properties and the microwave absorption behaviors of the MCCFs were determined in the form of epoxy matrix composites using a J-H hyster sis loop tracer and a vector network analyzer (VNA, at the X-band frequency range), respectively. According to the results, the XRD patterns of composites and nano powders showed that in temperature of 80 0C Fe3O4 phases have been formed. Moreover, the strongest reflection loss (RL) of MCCFs was recognized to be −7.8 dB (i.e. absorbing 83%) at 9.3 GHz for a layer containing 50%wt MCCFs with 2 mm in thickness. Electrophoretic deposition was introduced as a suitable method for production of MCCFs due to its low cost, easy productivity and time efficiency.

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