Papers by Keyword: Electromagnetic Shielding

Abstract: We have developed composite paint based on graphite, carbon black and some other not expensive components, which can be used as a clay court for sustainable buildings and electronic devices. This paint can reduce sufficiently the problem, which is related to the effects of electromagnetic radiation (EMR) on human health. Cellular and radiotelephones, as well as their broadcast antennas, especially which use of the 5G, 6G communication system, may pose a high risk of cancer, reproductive disorders, memory, cellular stress, neurological and mental disorders. The medical disorders are already often experienced by servicemen working at radar stations, observation posts and other similar facilities associated with high-frequency EMR. The effect of EMR is especially dangerous for children of preschool and school age, so, it is necessary to use similar paints first of all for such buildings. Carbon-based composite paints have been developed, which can be used as a clay court for sustainable buildings and electronic devices. This paint can reduce sufficiently the problem, which is related to the effects of electromagnetic radiation (EMR) on human health. Cellular and radiotelephones, as well as their broadcast antennas, especially which use of the 5G, 6G communication system, may pose a high risk of cancer, reproductive disorders, memory, cellular stress, neurological and mental disorders. The medical disorders are already often experienced by servicemen working at radar stations, observation posts and other similar facilities associated with high-frequency EMR. The effect of EMR is especially dangerous for children of preschool and school-age, so, it is necessary to use similar paints first of all for such buildings. It is also necessary to note the significant impact of EMR on electronic equipment. First of all, this is a well-known problem of providing the so-called "electronic compatibility", when simultaneously operating different electronic equipment (e.g., thermal imager and radio transmitter) interfere with each other. A number of scientific developments have been implemented and work is underway under the NATO SfS international grant in this area.

Abstract: Materials with high dielectric properties have become interested due to their important applications, mainly in electronics and energy storage. This study assesses the dielectric properties of epoxy composites containing silver nanoparticles (AgNPs) and carbon nanotube (CNT) composite materials. These samples' permittivity and reflective properties were measured using Vector Network Analyser (VNA) within the X-band frequency (8.2 – 12.4 GHz). Samples were prepared at various loading (0.1-5 wt.%), with various thickness of (0.5, 1.0, 1.5 and 2.0 mm). Regardless of the fillers loading and sample thickness, it was found that the values of real permittivity, er', remain constant along the frequency range. At the same sample thickness, it was found that the values of both er' and er'' increase as loading increases, indicating the function of AgNPs and CNT in enhancing the dielectric and electrical conductivity properties of epoxy composites, respectively. The highest value of er' is recorded as 5 F/m (at f = 8.2 GHz), measured at 5 wt.% loadings and 0.5 mm sample thickness. Measurement on S₁₁ parameters at f = 8.2 GHz indicated that the SE_R values are between 9 dB and 15 dB, with no obvious pattern observed, regardless of the fillers loading and sample thickness. This study highlights the dielectric properties improvement of epoxy composites by incorporating dual fillers.

Abstract: With the rise of electromagnetic radiation-based technologies, considerable attention has been drawn to developing and implementing innovative electromagnetic shielding materials. Carbon nanomaterials and conductive polymers have been appealing to both academia and industry as promising alternatives for the traditionally used metallic materials, owing to their lightness, flexibility, easy processability and resistance to corrosion, which are of special importance for textile applications. In this work, multiwalled carbon nanotubes (MWCNTs) and poly (3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) have been applied to cotton textile substrates by straightforward scalable dyeing and coating processes, respectively. These processes led to uniform and homogeneous coatings with distinct properties: the fabric coated with MWCNT presented higher thickness and lower loading of incorporated material than the textile coated with PEDOT:PSS (thickness: 995 μm vs. 208 μm; material loading: 9.4 wt.% vs. 70.7 wt.%). The electromagnetic shielding properties were outlined for each shielding textile in the frequency range of 5.85–18 GHz: an average shielding effectiveness of ~35.6 dB was obtained for MWCNT@tex, while PEDOT:PSS@tex reached ~38.3 dB. Thus, PEDOT:PSS provided enhanced radiation shielding with lower coating thickness, while the MWCNTs led to improved attenuation with less material usage. Shielding effectiveness values above 30 dB were obtained for both electromagnetic interference shielding textiles, which corresponds to an excellent classification for general use applications, such as casual clothing and maternity wear.

Abstract: Shielding materials play an essential role in the prevention of electromagnetic irradiation and electromagnetic interference from electric equipment. Physico-chemical modification of crumb rubber and devulcanised rubber leads to the formation of materials with distinctive properties suitable for the development of composites for electromagnetic protection. The current paper introduces an approach for secondary raw materials modification for production of composite mixtures, which could be used electromagnetic shielding materials. Experimental evaluation of electromagnetic shielding properties was performed. Devulcanised rubber-based composite materials are considered as electromagnetic shielding materials for equipment in transport systems and civil engineering applications.

Abstract: A two-step solvothermal method was employed to synthesize the Graphene/Fe₃O₄/BaTiO₃ (GFT). X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectra are used to observe the microstructure and magnetic properties of GFT, and the nanoparticles of Fe₃O₄ and BaTiO₃ were uniformly deposited on the surface of the graphene nanosheets. Then GFT filler and the silicone rubber were mixed to manufacture the electromagnetic shielding materials. The vector network analyzer was employed to evaluate the electromagnetic shielding effectiveness of the modified electromagnetic shielding materials. The influence of the mole ratio of the GFT constituents, the mass content of the filler on the electromagnetic shielding effectiveness was studied between 1 GHz and 20 GHz. It is shown that the GFT/silicone rubber has the best electromagnetic shielding effectiveness for 24:1:1 of graphene: Fe₃O₄: BaTiO₃ and 16 % GFT.

Abstract: Metal foams, having a great of specific surface areas and three-dimensional open cell structures, can be used for electromagnetic shielding and thermal management in electronics, battery electrodes in new energy, catalyst carriers in chemical engineering and lightweight structure in aerospace. The key performance indicators of these open cell metal foams are how to effectively control their pore structures such as pore diameter distribution and porosity and how to make it thinner that can meet different requirements for the component preparation. Summarized about three manufacturing processes are usually used to build metal foams. The first is well-known as physical process. The second is chemical or electrochemical method. The third is a combined process between physical and chemical processes. No matter what kind of process is selected to manufacture open cell metal foam, the specific surface area directly related to the microstructure of the foam is an important parameter in a material selection and design for its application.This paper will introduce a special powder composite plus manufacture process that is developed by Jiangsu Green Materials Hi-Tech. Co. Ltd. The leading manufacture process is a new one that is combined by powder metallurgy, casting, deformation and physical-chemical synthesis. It is environmentally friendly and recyclable from raw material selection, manufacturing process to thermal-mechanical treatment. This paper will also focus on the introduction of the microstructure characterization of open-cell metal foams such as copper, nickel, iron, silver and their alloying foams that we manufactured and give some examples to demonstrate their potential applications in the field of new energy, such as being an electrode for lithium-ion battery, membranes for fuel cell and super-capacitor, in the field of electronic engineering such as thermal management and electromagnetic shielding, in the field of chemical engineering such as separation and catalysts. These examples show their lead roles of these open-cell metal foams and different applications by our developed process.

Abstract: The paper develops analyses electromagnetic compatibility issues in electric vehicles. Particular techniques are developed involving special elements of tubular geometry based on the analytical solution of diffusion equation combined with standard finite elements, for analysis of electromagnetic shielding effectiveness in power cables due to power static converter operation. Particular simulations analyze the exposure levels due to variable frequency magnetic field on anatomically detailed human models in electric vehicle cabin environment. The results obtained have been compared to those found in the literature and to measured ones.

Abstract: This paper mainly introduces the origins, basic structures and family members of carbon, the focus is a new generation of nanomaterial－graphene. In the experiment, a series of tests are taking place firstly, such as SEM, TEM, XRD, XPS, BET, Infrared spectrum, Raman spectrum and Laser particle size analysis. The results show that the graphene has excellent mechanical properties, optical performance, electrical properties and conductive properties. Especially super conducting properties of graphene. Then the basic principle of electromagnetic shielding effectiveness, test methods and condition analysis are analyzed in this paper.

Abstract: First, briefly introduced the theory of electromagnetic shielding; second, analyzed electromagnetic shielding technology in practical and applied perspective, at the same time, pointed out the key points of electromagnetic shielding cabin design; at last, proposed improvement for the follow-up study.

Abstract: This paper introduces the principle and manufacture process of a film-taped metallic mesh, and the influence of the parameters of metallic mesh film on optical and electromagnetic features has also been analyzed. By using the flexographic printing technology, the metal mesh film with the line widthes of 15, 203040μm and the period of 300μm on PET substrates have been made, and the maximal electromagnetic shield effectiveness is more than 15dB. The results indicate that the optical and electrical performance of the metallic mesh film is inconsistent, and it is better to select a thinner line width and smaller period to obtain optimal shielding effectiveness.