Electromagnetic Interference Shielding Capability Research Articles

Transparent Conducting Graphene Hybrid Films To Improve Electromagnetic Interference (EMI) Shielding Performance of Graphene.

Conducting graphene-based hybrids have attracted considerable attention in recent years for their scientific and technological significance in many applications. In this work, conductive graphene hybrid films, consisting of a metallic network fully encapsulated between monolayer graphene and quartz-glass substrate, were fabricated and characterized for their electromagnetic interference shielding capabilities. Experimental results show that by integration with a metallic network the sheet resistance of graphene was significantly suppressed from 813.27 to 5.53 Ω/sq with an optical transmittance at 91%. Consequently, the microwave shielding effectiveness (SE) exceeded 23.60 dB at the Ku-band and 13.48 dB at the Ka-band. The maximum SE value was 28.91 dB at 12 GHz. Compared with the SE of pristine monolayer graphene (3.46 dB), the SE of graphene hybrid film was enhanced by 25.45 dB (99.7% energy attenuation). At 94% optical transmittance, the sheet resistance was 20.67 Ω/sq and the maximum SE value was 20.86 dB at 12 GHz. Our results show that hybrid graphene films incorporate both high conductivity and superior electromagnetic shielding comparable to existing ITO shielding modalities. The combination of high conductivity and shielding along with the materials' earth-abundant nature, and facile large-scale fabrication, make these graphene hybrid films highly attractive for transparent EMI shielding.

Lightweight Nanocomposites Based on Polypropylene and Aluminum Nanoparticles and Their Shielding Capability to Ionizing Radiation

Nanocomposites based on isotactic polypropylene and different contents of aluminum (Al) nanoparticles have been prepared in order to primarily analyze their electromagnetic interference shielding capability. Promising results have been attained in this area since values as high as 40 dB, which provide at least a 99% attenuation of the electromagnetic radiation, are reached. The good balance between shielding, sample weight, cost, and processability makes these lightweight materials a good alternative to replace neat metals for that application. Moreover, a complete structural and morphological characterization, as well as an evaluation of their dielectric behavior is also performed.

Lightweight nanocomposites based on poly(vinylidene fluoride) and Al nanoparticles: Structural, thermal and mechanical characterization and EMI shielding capability

Novel (nano)composites based on PVDF and different content of Al nanoparticles have been prepared in order to learn about their electromagnetic interference shielding capability. Very promising results are obtained, with an excellent balance between shielding and sample weight, so that these materials are potentially good alternatives to replace neat metals for that application. Moreover, a complete structural and morphological characterization, as well as an evaluation of their thermal and mechanical behavior, has been also performed.

An Investigation of the Electromagnetic Shielding Effectiveness of Ethylene Vinyl Acetate Elastomer Reinforced with Carbon Nanofillers

Electrically conducting polymeric composites are gaining popularity not only due to their light weight, corrosion resistance, flexibility and low cost, but also due to their electromagnetic interference (EMI) shielding ability. A novel ethylene vinyl acetate (EVA)-carbon nanofibre (CNF) nanocomposite has been successfully developed, and its electromagnetic interference shielding effectiveness (SE) was measured in the frequency range of 8–12 GHz. The dependence of SE on the applied electromagnetic frequency and the amount of filler loading has been evaluated. The SE of the composites was found to be directly proportional to the applied electromagnetic frequency and the amount of filler. Incorporation of 16 wt.% of CNF produced the optimum SE. The AC conductivity of the CNF reinforced EVA composites has also been measured in order to correlate the conductivity values with the SE of the respective composites. The level of filler loading governed the conductive network formation and hence the SE and conductivity. In order to do a comparative study of SE, three other carbon based nanofillers such as multiwalled carbon nanotube (MWCNT), expanded graphite (EG) and conductive carbon black (CB) have been used in this study. Morphological studies using transmission electron microscopy (TEM) supports various findings. These results indicate that CNF is an effective filler for the development of composites with excellent EMI shielding capability.

Composite electromagnetic interference shielding materials for aerospace applications

Electromagnetic interference (EMI) occurs when electronic devices are subject to electromagnetic radiation from unwanted sources at the same frequency ranges that these devices operate. Metals typically serve as excellent EMI shielding agents, but their heavy weight, high cost and susceptibility to forms of environmental degradation make them an undesired choice for many current electronic devices. Conversely fibre reinforced polymeric (FRP) composite materials are normally light weight, and can be cheaper to produce, but typically lack the inherent EMI shielding capabilities that may be required. This research work addresses the viability FRP composite materials for use as EMI shielding structures, specifically for aerospace applications . It was found that carbon fibre could suffice this purpose, but likely required filler materials to enhance electrical conductivity and shielding effectiveness (SE).

Plasma 처리 및 MmSH 사출방법으로 인한 PC/ABS와 PC상의 은도금 밀착성에 관한 연구

Polycarbonate has a high transmittance to light, low specific gravity, flexibility and cost-effectiveness that extends the application field of the polymer to bio-engineering, optics, electronic parts, etc. Moreover, electro plating of metallic film on PC could endow the parts the electromagnetic interference shielding capability. However, poor adhesion of copper on PC limited the wide usage in the industry. In this work, a composite(PC/ABS) and MmSH(Momentary mold Surface Heating) injection process were used to improve the plating characteristics; plating thickness, gloss and adhesion. Also plasma treatment and chemical treatment were employed for improving adhesion. Plating characteristics on PC/ABS were better than those on PC due to the anchoring effect of butadiene. MmSH injection process could ameliorate the gloss and coating adhesion. Also plating thickness and adhesion of PC and PC/ABS were increased by plasma treatment.

Influence of Process Parameters on T-Shape Tube HydroForming Characteristics for Magnesium Alloy

Due to the light weight and electromagnetic interference shielding capabilities in magnesium alloy material, it is widely utilized in 3C electronic components and automobile parts. However, its formability is very poor due to the phenomenon of negative strain hardening rate appearing as the deformation in large strain range, so it is usually formed as die casting or casting styles leads to much scrap, and manufacturing cost is thus increased. The objective of this study is to investigate the effect of process parameters on T-shape tube hydro-forming characteristics for magnesium alloy and it may offer the data resulting from the analysis to predict an acceptable product of tube fitting for magnesium alloy forming in industry. AZ31 magnesium alloy tube is used as the billet material for hydro-forming with hydraulic pressure as the main forming power combined with the mechanical auxiliary force from the punch to fabricate the T-shape tubing products. Finite element code DEFORM-3D is adopted to investigate the forming states of T-shape tube forming, by changing process parameters; such as punch velocity, hydraulic pressure, fillet radius of the die and tool-workpiece interface friction etc. to investigate the material flow of tube fitting, wall thickness variations, and stress and strain distributions. By qualifying the forming processes whether if it is completed or not, and synthesizing the overall analysis and judgment, we establish an admissible level of process parameter range for complete tube manufacture. The results show that suitable mechanical force can help material flow, prevent large strain deformation falling into the area of negative strain hardening rate, enhance magnesium alloy to become easy in forming and make tube fitting to be formed successfully.