Abstract:Carbon microcoils (CMCs) were deposited onto Al2O3substrates using C2H2/H2as source gases and SF6as an incorporated additive gas in a thermal chemical vapor deposition system. CMC-polyurethane (PU) composites were obtained by dispersing the CMCs in the PU with a dimethylformamide additive. The electromagnetic wave shielding properties of the CMC-PU composites were examined in the frequency range of 0.25–1.5 GHz. The shielding effectiveness (SE) of the CMCs-PU systematically increases with increasing the conten… Show more
“…27 The high absorption of the developed bimetal hybrid composites can be attributed to the combination of high electrically conductive materials (wire meshes, carbon fiber) and the material with high magnetic permeability. 5,7,27,28 The dielectric constant of matrix composites used to fabricate bimetal/CFRP composites played also an important role in increasing the absorption properties of the samples. 27,28 Figure 11.Maximum, average, minimum of absorption and reflection loss.…”
Section: Resultsmentioning
confidence: 99%
“…5,6 Therefore, the main mechanisms of electromagnetic shielding in the materials are reflection, absorption, and multi-reflections. 5,7–9 The capacity of a material to shield EMIs is defined as shielding effectiveness (SE, unit:dB).…”
Carbon fiber-reinforced plastic (CFRP) composites, owing to their lightweight and strength-weight ratio, are being used in many applications to replace traditional metallic materials and their alloys. The combination of polymeric composites with metallic materials can provide a significant impact in engineering applications. This paper evaluates electromagnetic interference shielding of bimetal-carbon prepreg fibers textile composite materials. Prepreg carbon fibers and metal wire mesh are used to make electromagnetic interference shielding samples. The material samples consist of making plain weaves of metal wire mesh and carbon prepreg and stack them with prepreg carbon fiber layers. In order to produce plain woven fabrics, wefts were made of prepreg carbon fibers and warps were made of wire meshes. In each woven fabric, two yarns of different metal wire meshes were alternated one after another. The combination of conductive wire meshes such as stainless steel-copper, stainless steel-nickel, and copper-nickel in a woven fabric was considered. The electromagnetic shielding effectiveness was evaluated for each textile composite material based on ASTM 4935-99. Results showed a possible application of these materials for electromagnetic interference shielding with higher absorption. The best electromagnetic interference shielding performance was obtained for a combination of stainless steel-copper-CFRP with a shielding effectiveness of 131.6 dB. The absorption losses for all samples were about 82% of electromagnetic interference shielding effectiveness. The mechanical properties and scanning electron image of fabricated samples were also investigated.
“…27 The high absorption of the developed bimetal hybrid composites can be attributed to the combination of high electrically conductive materials (wire meshes, carbon fiber) and the material with high magnetic permeability. 5,7,27,28 The dielectric constant of matrix composites used to fabricate bimetal/CFRP composites played also an important role in increasing the absorption properties of the samples. 27,28 Figure 11.Maximum, average, minimum of absorption and reflection loss.…”
Section: Resultsmentioning
confidence: 99%
“…5,6 Therefore, the main mechanisms of electromagnetic shielding in the materials are reflection, absorption, and multi-reflections. 5,7–9 The capacity of a material to shield EMIs is defined as shielding effectiveness (SE, unit:dB).…”
Carbon fiber-reinforced plastic (CFRP) composites, owing to their lightweight and strength-weight ratio, are being used in many applications to replace traditional metallic materials and their alloys. The combination of polymeric composites with metallic materials can provide a significant impact in engineering applications. This paper evaluates electromagnetic interference shielding of bimetal-carbon prepreg fibers textile composite materials. Prepreg carbon fibers and metal wire mesh are used to make electromagnetic interference shielding samples. The material samples consist of making plain weaves of metal wire mesh and carbon prepreg and stack them with prepreg carbon fiber layers. In order to produce plain woven fabrics, wefts were made of prepreg carbon fibers and warps were made of wire meshes. In each woven fabric, two yarns of different metal wire meshes were alternated one after another. The combination of conductive wire meshes such as stainless steel-copper, stainless steel-nickel, and copper-nickel in a woven fabric was considered. The electromagnetic shielding effectiveness was evaluated for each textile composite material based on ASTM 4935-99. Results showed a possible application of these materials for electromagnetic interference shielding with higher absorption. The best electromagnetic interference shielding performance was obtained for a combination of stainless steel-copper-CFRP with a shielding effectiveness of 131.6 dB. The absorption losses for all samples were about 82% of electromagnetic interference shielding effectiveness. The mechanical properties and scanning electron image of fabricated samples were also investigated.
“…Moreover, it was noticed that the EMSE performance of each composite increased almost cumulatively while the content of VGCNFs increased in the structures due to the high aspect ratio triggered the conductive network formation at even very low nanofiller loading [12]. carbon fibers are defined as more absorbent materials rather than being reflective in terms of the attenuation of electromagnetic waves in especially increasing frequencies [44][45][46][47].…”
Section: Figure 5 Four Point Probe Schematicsmentioning
The purpose of this study is to observe effect of incorporating vapor grown carbon nanofibers with various amounts in polyvinylidene fluoride matrix in terms of mechanical strength and electromagnetic shielding effectiveness. Thermoplastic conductive nanocomposites were prepared by heat pressed compression molding. Vapor grown carbon nanofibers were utilized at various weight ratios (1 wt. %, 3 wt. %, 5 wt. % and 8 wt. %) as conductive and reinforcing materials. Polyvinylidene fluoride was used as a thermoplastic polymer matrix. SEM analysis was conducted in order to characterize the morphology and structural properties of the nanocomposites and results revealed well dispersion of carbon nanofibers within the matrix for all concentrations. Mechanical characteristics were investigated according to standards. Findings proved that overall increments of 16%, 37,5% and 56% were achieved in terms of tensile strength, elasticity modulus and impact energy, *: Corresponding author E-mail: acyilmaz@cu.edu.tr 1 respectively where a total reduction of 44.8% was observed in terms of elongation for 8 wt.% vapor grown nanofiber matrix compared to that of 0 wt.%. Electromagnetic shielding effectivenesses of the nanocomposites were determined by standard protocol using coaxial transmission line measurement technique in the frequency range of 15-3000 MHz. It was observed that resistance, sheet resistance and resistivity of nanocomposites depicted substantial reduction with the increment of nanofiber content. Nevertheless, it was observed that nanofiber content, dispersion and network formation within the composites were highly influent on the electromagnetic shielding effectiveness performance of the structures.
“…In order to address these problems the development of EMI shielding materials received increasing attention [1][2][3]. Carbon composites have outstanding potential for use in EMI shielding [4][5][6][7][8][9] due to their excellent electrical properties, low density, high aspect ratio, and high strength and modulus. However the electrical conductivity of carbon materials is considerably lower than that of metals and therefore a greater amount of carbon material is needed to achieve the same shielding effect.…”
Electromagnetic interference (EMI) shielding materials made of Ni-Co coated on web-like biocarbon nanofibers were successfully prepared by electroless plating. Biocarbon nanofibers (CF) with a novel web-like structure comprised of entangled and interconnected carbon nanoribbons were obtained using bacterial cellulose pyrolyzed at 1200°C. Paraffin wax matrix composites filled with different loadings (10, 20, and 30 wt%, resp.) of CF and Ni-Co coated CF (NCCF) were prepared. The electrical conductivities and electromagnetic parameters of the composites were investigated by the four-probe method and vector network analysis. From these results, the EMI shielding efficiencies (SE) of NCCF composites were shown to be significantly higher than that of CF at the same mass fraction. The paraffin wax composites containing 30 wt% NCCF showed the highest EMI SE of 41.2 dB (99.99% attenuation), which are attributed to the higher electrical conductivity and permittivity of the NCCF composites than the CF composites. Additionally, EMI SE increased with an increase in CF and NCCF loading and the absorption was determined to be the primary factor governing EMI shielding. This study conclusively reveals that NCCF composites have potential applications as EMI shielding materials.
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