Carbon encapsulated nanoscale iron/iron-carbide/graphite particles for EMI shielding and microwave absorption

Abstract

Homogenously dispersed nanoparticles having a magnetic core and graphitic-carbon shells in amorphous carbon globules are prepared using a low-cost pyrolysis technique. Synergetic microwave absorption in carbon globules embedded with nanoscale iron/iron-carbide graphite (FeC) particles via dielectric, magnetic and Ohmic losses is emphasized in this work. The electromagnetic interference (EMI) shielding properties of the FeC nanoparticles dispersed in polyvinylidene fluoride (PVDF) are studied in the 8-18 GHz frequency range and compared with those of PVDF composites containing similar weight fractions of conducting/magnetic phase micro-particles such as carbonyl iron (CI) or electrolytic iron (EI) or a similar amount of amorphous carbon phase such as amorphous carbon (a-C) globules. The PVDF/FeC composite shows a maximum SE value of -23.9 dB at 18 GHz, as compared to the SE for the other composites. The enhanced EMI shielding in the PVDF/FeC composite is attributed to the increased interfaces of the nanoscale particles, which facilitate enhanced Maxwell-Wagner interfacial polarization. The homogenous dispersion of iron and iron-carbide phases in the carbon matrix of the FeC sample enhances the interfacial polarization and multiple internal scattering of the penetrated EM waves, which get synergistically attenuated by the Ohmic, magnetic and dielectric losses. Based on complex permittivity and permeability results we have calculated the Reflection Loss (RL) of the PVDF/FeC composite. The PVDF-FeC composite shows a RL peak of -40.5 dB for a 4.3 mm thick specimen positioned at 5 GHz frequency. The RL peak is explained using the quarter-wave cancellation model. Our work demonstrates that incorporating carbon globules containing nanoscale magnetic and conducting particles in a polymer matrix, provides an effective way to enhance EMI shielding via absorption of the EM wave in a lightweight thin composite coating.

Double-layer metal mesh etched by femtosecond laser for high-performance electromagnetic interference shielding window

“…The development of transparent EMI shielding materials is imperative, but the existing great challenge is how to balance the inherent contradiction between the high optical transmittance and the strong shielding efficiency. [4][5][6][7][8] Tremendous efforts have been committed to achieving transparent EMI shielding using a number of strategies and a variety of materials, including transparent conductive oxide, ultra-thin metal lms, various shapes of metal grids with micro periods, bandpass frequency selective surface, silver nanowire, graphene and other carbon-based materials. [9][10][11][12][13][14] Among them, indium tin oxide (ITO) is currently used in transparent coating, exhibiting excellent visible light transmittance and strong electromagnetic shielding efficiency.…”

Synergistic effect of double percolated co‐supportive MWCNT‐CB conductive network for high‐performance EMI shielding application

“…The extensive growth in the electronic industry and telecommunication systems in the recent past has made electromagnetic interference (EMI) a major concern . EMI is defined as the radiated or conducted electromagnetic radiations from an electronic device under its operation that can interfere in the proper functioning of neighboring electronic circuits and is considered as a new form of environmental pollution that can cause radiative damage to living beings . Today, developing an efficient EMI absorbing material replacing conventional metallic shields is an important quest.…”

“…1 EMI is defined as the radiated or conducted electromagnetic radiations from an electronic device under its operation that can interfere in the proper functioning of neighboring electronic circuits and is considered as a new form of environmental pollution that can cause radiative damage to living beings. [2][3][4] Today, developing an efficient EMI absorbing material replacing conventional metallic shields is an important quest. Conventional metallic shielding material possesses several disadvantages such as being corrosive, heavy, and stiff, and moreover shielding is by reflection which will contribute minimally in reducing EM pollution.…”

Effect of Coral‐Shaped Yttrium Iron Garnet Particles on the EMI Shielding Behaviour of Yttrium Iron Garnet‐Polyaniline‐Wax Composites

“…They lack flexibility in use and their high density makes them heavier and unfavourable for practical EMI shielding applications. Therefore, carbon based materials such as carbon black, carbon globules, carbon fibers, graphite, graphene, carbon nanotubes, graphene oxide, and reduced graphene oxideetc., have gained merit over metallic shields owing to their high electrical conductivity, flexibility and corrosion resistance. However, high cost of carbon nanotubes as well as cumbersome synthesis process makes these carbon based materials uneconomical for EMI shielding applications.…”