Electromagnetic Interference Shielding In X-band Research Articles

The role of magnetic nano CoFe2O4 and conductive MWCNT/graphene in LDPE-based composites for electromagnetic interference shielding in X-band

The use of polymer composites containing ferrite based magnetic fillers and conducting fillers are highly appreciated as materials for microwave shielding. In this regard, herein we present systematic optimization of compositional parameters by varying CoFe 2 O 4 and MWCNT/Graphene nanoplatelets to achieve efficient electromagnetic shielding in Low density polyethylene polymer. The magnetic filler, CoFe 2 O 4 was prepared by facile solution combustion process and the chemically exfoliated Graphene and CVD-derived MWCNT are used as conducting filler. Various compositions containing different weight ratios of CoFe 2 O 4 and Graphene nanoplatelets on the EMI shielding efficiency of LDPE composite is studied using vector network analyzer in the frequency range of 8–12 GHz. The critical concentration of all the materials in bringing synergy was evaluated. The combination of LDPE:MWCNT:GNP:CoFe 2 O 4 : 50:5:40:5 was found to be optimum concentration to bring a synergetic effect for gaining excellent dielectric, ohmic and magnetic losses in the X-band. Maximum total shielding effectiveness of about 49 dB was achieved at 10.3 GHz within the frequency range studied. • The use of magnetic CoFe 2 O 4 and carbon based MWCNT/ Graphene as fillers in LDPE matrix for enhanced shielding behavior. • Systematic optimization of the ferrite, carbon nanotubes and graphene is carried out to achieve maximum shielding effectiveness. • The synergetic effect is proved at an optimum fillers concentration and are correlated to the impedance and conductivity variations of the composites.

Synergistic effects of graphene nanoplatelets on X-band electromagnetic interference shielding, thermal expansion and thermal stability of poly(ether-ketone) based nanocomposites

In this work, the electromagnetic interference shielding effectiveness (EMI-SE) of the poly(ether-ketone) (PEK)-graphene nanoplatelets (GNP) nanocomposites fabricated by planetary ball mill followed by hot pressing were investigated in X-band (8.2–12.4 GHz). A percolation threshold of about 0.4 vol% GNP was obtained. The electrical conductivity was increased to about 0.02 S/cm with an EMI-SE of ~33 dB for 1 mm thick 5 vol% GNP filled PEK nanocomposite. This higher value is corresponding to more than 99.95% blocking of the EMI. The EMI-SE increases with increasing thickness of the nanocomposite. The thermal stability and the char yield of the nanocomposites reinforced with 5 vol% GNP were found to increase to 570 °C and to 61.6%, respectively. The dimensional stability of the nanocomposites was also increased compared to neat PEK.

Design and development of polymeric nanocomposite reinforced with graphene for effective EMI shielding in X-band

The effect of filler material concentration on Electromagnetic Interference (EMI) Shielding Effectiveness (SE) of polymeric nanocomposites has been studied. Computational model was developed for shielding performance of graphene polymeric nanocomposites. Nanocomposites were fabricated using High Pressure Resin Transfer Molding (HPRTM) method, latter EM shielding properties were measured experimentally using waveguide technique. It is observed that SE increases with increase in wt% of graphene. From the results, it is perceived that nanocomposite with 2.5 wt% of graphene shows good shielding with the range of −27 dB to −30 dB, doubled in comparison to pure polymeric composite. Numerical simulations of various graphene nanocomposites have been carried out for the prediction of SE while incorporating EM properties of corresponding nanocomposite as input. Excellent agreement between numerical simulations and experimental results has been observed. The developed numerical model predicts SE values of graphene nanocomposites in −30 dB range which certainly falls in the X-band.

Electromagnetic interference shielding in X-band with aero-GaN

We investigate the electromagnetic shielding properties of an ultra-porous lightweight nanomaterial named aerogalnite (aero-GaN). Aero-GaN is made up of randomly arranged hollow GaN microtetrapods, which are obtained by direct growth using hydride vapor phase epitaxy of GaN on the sacrificial network of ZnO microtetrapods. A 2 mm thick aero-GaN sample exhibits electromagnetic shielding properties in the X-band similar to solid structures based on metal foams or carbon nanomaterials. Aero-GaN has a weight four to five orders of magnitude lower than the weight of metals.

SiC nanofibers modified Si3N4 ceramics for improved electromagnetic interference shielding in X-band

Home-made SiC nanofibers were introduced into Si3N4 matrix for enhanced electromagnetic interference (EMI) shielding properties. The microstructural characterization revealed that SiC nanofibers modified Si3N4 ceramic is composed of SiC conductive networks made of uniformly distributed SiC nanofibers, micro-pores and insulating Si3N4 matrix. Moreover, EMI shielding effectiveness (SET) for SiC nanofibers modified Si3N4 ceramic is dependent on SiC nanofibers content. When the SiC nanofibers content is increased from 0 to 8wt%, the EMI SET of as-prepared ceramics increased from 3.43–4.15dB to 5.58–9.31dB. Due to the low electrical conductivity of as-prepared ceramics, multi-reflection caused by the micro-pores and nanofibers networks is mainly responsible for the EMI shielding. The study indicates that introduction of SiC nanofibers would be a favorable solution for Si3N4 based thermostructural material with an improved EMI shieding.