Superior Shielding Effectiveness Research Articles

An Experimental Study on Electromagnetic Shielding Effectiveness and Impact Resistance of UHPC for Protective Facilities

The research was conducted on incorporating short carbon fiber and multi-layer graphene into ultra-high performance concrete (UHPC) to improve the dynamic mechanical performance and electromagnetic shielding effectiveness (SE). In the electromagnetic shielding effectiveness testing, the results shown that UHPC with uniformly distributed conductive fibers exhibited superior shielding effectiveness at high frequencies. In comparison to normal concrete, the UHPC demonstrated the capability to withstand higher impact energy. Simultaneously enhancing both electromagnetic shielding characteristics and dynamic mechanical performance of cementitious materials can be challenging. In this study, employing a composite structure was effective solution to overcome this issue. In accordance with the experimental results, a scaled testing protective facility has been constructed, and the research results could provide the reference for the design and construction of protective structures.

Investigation of electromagnetic shielding effectiveness of nano silver coated stainless steels

This paper presents the shielding effectiveness (SE) of various nanosilver-coated stainless steels (201, 304, 316 and 430), using a coaxial transmission line setup with waveguides and a vector network analyzer (VNA) in accordance with ASTM 4935 standards. The conducted experiments revealed excellent SE outcomes, indicating that the silver-coated stainless steel samples exhibited notably superior SE performance compared to their uncoated counterparts. The importance of SE in electromagnetic compatibility (EMC) applications, particularly in minimizing electromagnetic interference (EMI) and safeguarding sensitive electronic devices, is well acknowledged. This study further explored the shielding effectiveness of a novel hybrid material, nano silver (Ag) coated different stainless steels, with a focus on its potential for improved EMI shielding capabilities. Experimental measurements were conducted in the 5G frequency domain.It was found that nanosilver coating increased the SE of stainless steels by between 5 and 12 dB. This enhancement attributed to the incorporation of nanostructured silver particles on the stainless steel surface, which facilitates enhanced reflection of electromagnetic waves, resulting in superior shielding performance. Moreover, this study underlying the mechanisms of SE through various analyses, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). In summary, this research has demonstrated that nano silver coating increases the SE value of materials. This result suggests that all other materials can be used to increase the SE value. The results have implications for advancing electromagnetic shielding technologies and promoting the development of robust EMI shielding solutions in various industrial applications where effective shielding is of paramount importance.

Enhanced EMI shielding effectiveness of Ba1.8Sr0.2Zn2Fe11.9Dy0.1O22/CaTiO3/Ti3C2Tx-MXene composite

The rapid growth of electronics has resulted in significant electromagnetic interference and threatens the human biological system. As a result, producing lightweight, high-performance electromagnetic interference shielding materials is crucial to safeguard human and technological devices from exposure to electromagnetic interference. For the first time, Ba1·8Sr0·2Zn2Fe11.9Dy0.1O22, CaTiO3, Ti3C2Tx-MXene, and their composites were synthesized with superior shielding effectiveness in the X-band frequency range. This unique combination of magnetic, dielectric, and conducting components contributes to high total shielding effectiveness in their composites. The saturation magnetization, 35.36, emu/g 23.00 emu/g, 22.59 emu/g, and 11.79 emu/g obtained from the composites are essential for improving the shielding effectiveness. Ba1.8Sr0.2Zn2Fe11.9Dy0.1O22/Ti3C2Tx-MXene (ratio 2:1) composite has a higher total shielding effectiveness of around −88.29 dB at 11.8 GHz frequency. Furthermore, this observed increased shielding effectiveness was attributed to an absorption-dominated shielding mechanism. This study reveals that the Ba1·8Sr0·2Zn2Fe11.9Dy0.1O22/CaTiO3/Ti3C2Tx-MXene composite is a potential EMI shielding material.

High-conductivity nickel shells encapsulated wood-derived porous carbon for improved electromagnetic interference shielding

Biomass-derived carbon materials, especially from wood, have attracted great interests in electromagnetic interference (EMI) shielding ascribed to their sustainability and unique porous structures. However, it still lacks an effective approach to optimize its shielding performance through the microstructure design. Here, core@shell structure nickel encapsulated wood-derived porous carbon (PC) is prepared to improve the EMI shielding performance of porous carbon, in which the high-conductivity nickel shells is obtained through a chemical plating approach. The shielding effectiveness (SE) can reach 83 dB at 9.5 GHz, which is much higher than other reported shielding materials. Experimental results coupled with numerical simulations indicate that the surface and interface electric field distributions could result in a rapid transportation of EM energy and thus enhance the EMI shielding performance. Moreover, the shielding thin films prepared by such microparticles could demonstrate a superior SE of 104.5 dB with a normalized SE of 139.4 dB/mm. Our study opens a new pathway for designing EMI shielding materials based on biomass-derived core@shell structural carbon materials.

Metal Mesh-Based Infrared Transparent EMI Shielding Window with Balanced Shielding Properties over a Wide Frequency Spectrum

Metal mesh films have been shown to be a promising strategy to effectively mitigate the growing issue of electromagnetic interference (EMI) in optoelectronic systems. To achieve superior shielding effectiveness, it is common to increase the thickness of the mesh film. However, mesh-based shielding materials have frequency-dependent shielding effectiveness that decreases as the frequency increases. Simply increasing the thickness of the mesh cannot effectively enhance the EMI shielding effectiveness at high frequencies. This will further lead to challenges such as increased processing difficulties and higher costs. In this paper, we present an infrared transparent electromagnetic shielding window based on metal mesh with irregular patterns and proper thickness. The mesh coating is fabricated on a sapphire substrate using ultraviolet photolithography technology and exhibits an efficient electromagnetic shielding effectiveness of more than 20 dB over the wide frequency range of 1.7–18 GHz while maintaining high infrared optical transparency. More importantly, there is no distinct variation in shielding effectiveness between low and high frequency ranges, demonstrating a balanced shielding characteristic across a broad frequency band. This work could be crucial in designing cost-effective and efficient EMI shielding windows for optoelectronic systems.

Self-assembly hollow magnetoelectric composites emerging tunable property between microwave absorption and shielding with light-weight and broad bandwidth

In generally, microwave absorption and shielding are a pair of conjugate properties, which merely achieves in the same system of electro-magnetic materials. In this work, Prussian blue analogues (PBA) derived hollow CoNi@C frames embedding with reduced graphene oxide (rGO) are successfully synthesized through a facile self-assembly method. In addition to considerable dielectric loss originating from high conductivity components of C@rGO, magnetic loss is also impressive due to the dynamic magnetic coupling interaction among the closely spaced magnetic units of CoNi. Finally, the CoNi@C@rGO composite with an extremely low loading ratio of 30 wt% reveals a strong reflection loss of − 48 dB and a broad absorption bandwidth of 6.24 GHz concurrently at a thin thickness of 1.6 mm. The launch field is obviously suppressed by covering the CoNi@C@rGO coating and RCS is below − 10 dBm2 within the entire detection angles (−90°<theta<90°). Meanwhile, superior shielding effectiveness (SE) of 66.2 dB is also achieved in the CoNi@C@rGO composite at 3.59 mm. It demonstrates that our work provides an effective and facile approach to make a transformation between microwave absorption and microwave shielding in the same material system.

Scalable production of bioinspired MXene/black phosphorene nanocoatings for hydrophobic and fire-safe textiles with tunable electromagnetic interference and exceeding thermal management

Multifunctional fire-safe textiles are urgently needed to meet the application requirements under harsh environments, e.g., high-frequency environments. However, it is rather tough to realize scalable production of multifunctional fire-safe textiles by constructing coatings. To tackle the hurdles above, multifunctional fire-safe cotton fabric was prepared though a blade-coating strategy (using black phosphorus and Ti3C2Tx nano-dispersion ink), followed by hydrophobic treatment with poly (dimethylsiloxane) coating. The resultant textiles with the coating of micra-like structure exhibit excellent water resistance with a water contact angle of up to 93° and excellent heat response within 10 s to the original temperature. Furthermore, the as-designed textiles demonstrate high flame retardancy and superior shielding effectiveness (SE) of 58 dB, which is much better than the reported treated fabric. The final treated fabric with high electromagnetic interference shielding effectiveness is suitable for most commercial applications. This work provides a promising strategy to produce functional textiles with superior electromagnetic interference and exceeding thermal management at a large scale, showing potential applications in electronic, electrical, and military fields.

Enhanced Electromagnetic Absorption of Cement Composites by Controlling the Effective Cross-sectional Area of MXene Flakes with Diffuse Reflection Based on Carbon Fibers

• Re-vitalizing MXene’s superior SE performance in the cement composites by adding CF. • The cement composites’ SE reached 41.35 dB with MXene (0.5 wt%) and CF (2.5 wt%) • SE limit of MXene in cement comes from low concentrations and random orientations. • Diffuse reflections of CF compensate the reduced cross-sectional area of MXene. We studied the potential application of MXene flakes for electromagnetic interference (EMI) shielding in cement matrices. Despite their superior electrical and shielding properties, MXene flakes cannot be used in cement for building construction owing to the poor effective cross-sectional area, which is induced by low concentrations and random orientations of small MXene flakes. This reduced the MXene effect on EMI shielding, which could be compensated by co-inserting carbon fibers for diffuse reflections, recovering the reduced effective cross-sectional area of MXene flakes for incident EM waves. Even with a small amount (0.5 wt%) of MXene with 2.5 wt% of carbon fibers, the shielding effectiveness (SE) of cement composites was enhanced to 41.35 dB at 1.0 GHz at a thickness of 3 mm, which is 800 % enhanced compare with the cement composite only with MXene (3.0 wt%). Scanning electron microscopy and permittivity measurements were performed after SE measurements to further analyze the multi-interface structure in detail. This synergetic EMI SE enhancement behavior caused by adding layered materials can be an efficient way to improve the SE of constructing materials with applicable fluidity to form building construction.

Ultrathin freestanding PDA-Doped rGO/MWCNT composite paper for electromagnetic interference shielding applications

The scalable and controllable preparation of carbon nanomaterial-based scaffolds with superior electromagnetic interference (EMI) shielding properties in addition to being ultrathin, robust, lightweight, flexible, and foldable is a challenging task. However, commonly used techniques such as integrating conducting moieties and high-temperature annealing cannot simultaneously meet the demands of high specific shielding effectiveness (SSE), robustness, and flexibility. Here, we adopted a novel PDA reduction technique to integrate various functionalities, including a nitrogen doping source, extended reduction of GO, and a large accessible area to accommodate multiwall carbon nanotubes (MWCNTs). The prepared ultrathin PDA-rGO/CNT composite sheet exhibited a low density (0.26 g/cm3), high flexibility, and superior shielding effectiveness (SE) under a wide range of microwave frequencies (i.e., the X band and Ku band). The total shielding effectiveness (SET) reached 47.6 dB and 48.7 dB in the X band and Ku band, respectively, at a thickness of 82 µm and a high SSE; in particular, the SE/density reached a maximum value of 183.3 and 187.3 dB cm3/g, respectively, which are superior to those of previously reported studies. This comprehensive study revealed the synergistic effect of PDA doping and MWCNTs, resulting in excellent shielding properties. Hence, this superior SSE and flexibility makes ultrathin lightweight PDA-rGO/CNT composite sheets a suitable candidate for replacing metallic counterparts for foldable and wearable electronic components.

Lightweight microwire/graphene/silicone rubber composites for efficient electromagnetic interference shielding and low microwave reflectivity

Most traditional fillers used in electromagnetic shielding composites require high loading, uniform distribution and complicated structures for modest property enhancement. Here, we propose a simple shielding system incorporating magnetic microwires M and graphene fibers G in different arrangements. Integrating both fillers in the composite resulted in superior shielding effectiveness (SE) with respect to incorporating either individual type of filler, due to improved absorption efficiency, impedance matching and polarization triggered by different arrangements of the fillers. Randomly dispersed arrays provided a maximum shielding of 6 dB for equal amount of G and M, in which polarization effects at the interface between the two regions contributed to the SE value. The highest SE of 18 dB (98.4% attenuation) was reached by the MMMGGG periodic arrays with merely 0.059 wt% filler loading enabled by the optimized arrangement and wave attenuation from the microwires dielectric/magnetic response. The normalized SE of this composite was about two to four orders of magnitude higher than that of many other shielding candidate materials. High SE, low loading, simple structure, and multifunctionality make these composites attractive for several applications. Moreover, tailoring topological and structural factors of both fillers would facilitate further SE enhancement without sacrificing the important lightweight advantage.

Simulation of shielding parameters for TeO2-WO3-GeO2 glasses using FLUKA code

Abstract This paper aimed to report the results on the investigation of photon attenuation parameters for TeO2-WO3-GeO2 glasses using FLUKA Monte Carlo code. In order to test the validity of the present code, the computational values of mass attenuation coefficients have been in confirmation with those of both previously published experimental data (MoO3-B2O3-Bi2O3) and XCOM database at various energies between 356 and 1330 keV. The relative deviation between FLUKA and experimental data is below 5.19% while the difference between the present code and XCOM database is found to be almost 2%. Therefore, the estimated results are in good agreement to each other and exhibited that FLUKA simulation is an alternative technique in determining the shielding performance of the present glass system. Additionally, mean free path and half-value layer results were calculated and it was concluded that among the selected glasses, TeWGe5 sample has superior shielding effectiveness.

Electromagnetic interference shielding properties of graphene/MWCNT hybrid buckypaper

A type of lightweight and flexible graphene/multi-walled carbon nanotube (MWCNT) hybrid buckypaper (BP) is fabricated, which show superior shielding effectiveness (SE) of electromagnetic interference and without polymer. The EMI SE of graphene/MWCNT hybrid BP with thickness of 130 μm is up to ∼51 dB at 8 GHz, which is much higher than that of pure MWCNT BP with same thickness (∼32.5 dB) and the best electrical conductivity is up to 10,000 S/m. More important, the improvement in EMI SE is contributed to the SE absorption, while the SE reflection is almost unchanged. This paper-like material is smooth, tough, and flexible enough to be attached on the complex curved surface structure. A facile way to fully develop graphene and MWCNT in lightweight and flexible EMI shielding materials and devices is provided here.

Mechanically robust conductive carbon clusters confined ethylene methyl acrylate–based flexible composites for superior shielding effectiveness

Arresting of conducting carbon black into polymeric matrix to develop flexible and light weight composite has been a widely practiced platform. Extensive development of telecommunication creates a major vexations regarding radiation pollution. Thereafter, we have been motivated to develop low‐cost, flexible composites of specialty carbon black VXC (Vulcan XC 72)–filled ethylene methyl acrylate (EMA) by mechanical mixing technique. Developed composite has significant conductivity (6.67 × 10−4 S cm−1) with promising mechanical and thermal properties. Dispersion of high‐structured carbon blacks in EMA was investigated by small angle X‐ray scattering to reflect the dependency of conducting mesh formation on dispersion. Interconnected filler network development has been visualized by field emission scanning electron microscope and high‐resolution transmission electron microscope. Electromagnetic interference shielding value in the X band has calculated to be 30.8 dB. Such features can make this EVXC (EMA‐Vulcan XC 72) composite a useful alternate for flexible electromagnetic interference shielding material.

Ultralight, super-elastic and volume-preserving cellulose fiber/graphene aerogel for high-performance electromagnetic interference shielding

Ultralight cellulose fiber/thermally reduced graphene oxide (CF/RGO) hybrid aerogel with super-elasticity and excellent electromagnetic interference (EMI) shielding capability was fabricated through lyophilization and carbonization process. CF/RGO aerogel with 5 mm thickness exhibits high EMI shielding effectiveness (SE) of ∼47.8 dB after annealing at 1000 °C with 5% hydrogen-argon mixture atmosphere. The superior SE is mainly ascribed to the cellular structure and good electrical conductivity of aerogel. The density of CF/RGO aerogel is as low as 2.83 mg/cm3, leading to ultrahigh specific shielding effectiveness (up to 33780 dB cm2/g). The volume/shape of obtained monolithic carbon material can be preserved very well after thermal treatment. The effects of RGO content and annealing conditions on EMI shielding and mechanical properties were investigated. Moreover, the hybrid aerogel possesses excellent mechanical resilience even with large strain (80% reversible compressibility) and outstanding cycling stability. In addition, adjustable EMI shielding capability could be realized by simple mechanical compression. These results demonstrate a promising and facile approach to fabricate low-cost and volume-preserving porous carbon material with superior and tunable EMI shielding performance for potential applications in aerospace and wearable electronic devices.

The intelligent concrete: a new, economical technique for architectural shielding of buildings

An innovative technique is presented for global shielding of new or renovated large facilities, whereas ordinary concrete is replaced by special filament-loaded concrete plus a steel mesh surface covering, resulting in a superior Shielding Effectiveness. The screen-mesh provides excellent reflection characteristics below ≈ 100MHz, progressively replaced by the absorption losses of metallic fibers that takes over above 50-100MHz. Besides the material itself, this intelligent concrete© offers the advantage of being incorporated while the prime building work is in progress, using techniques that impede very little the classical construction routines, and still result in a facility whose shielding performances, reaching 50-60dB, are widely sufficent for the needs of critical sites. An ensemble of specific mouting hardware for the interior finition is also described that allows to take advantage of the material properties without the seams and penetration leakages often found in such applications.

TiO2 hybrid polypropylene/nickel coated glass fiber conductive composites for highly efficient electromagnetic interference shielding

A highly efficient electromagnetic interference shielding composite based on nickel coated glass fibers (NCGFs) and titanium dioxide (TiO2) filled polypropylene (PP) is fabricated via the simple melt blending method. Superior shielding effectiveness of 44.5 dB can be achieved with only 1.12 vol% Ni and 0.8 vol% TiO2 loadings owning to the well-formed conductive network and interfacial polarization effect of TiO2. The conductive Ni layer coating on the surface of glass fibers constructs an efficient conductive network due to its interfacial distribution between GF and PP. This interconnected Ni network provides fast electron transport channels to absorb the electromagnetic waves. Meanwhile, TiO2 dispersed among the network of NCGFs induces more interfacial polarization, and thus produces a synergistic effect to enhance the shielding effectiveness of composite. Such composite would be considered as a promising electromagnetic shielding material in aerospace and electronics.

Towards efficient electromagnetic interference shielding performance for polyethylene composites by structuring segregated carbon black/graphite networks

An electromagnetic interference (EMI) shielding composite based on ultrahigh molecular weight polyethylene (UHMWPE) loaded with economical graphite-carbon black (CB) hybrid fillers was prepared via a green and facile methodology, i.e., high-speed mechanical mixing combined with hot compression thus avoiding the assistance of the intensive ultrasound dispersion in volatile organic solvents. In this composite, the graphite-CB hybrid fillers were selectively distributed in the interfacial regions of UHMWPE domains resulting a typical segregated structure. Thanks to the specific morphology of segregated conductive networks along with the synergetic effect of large-sized graphite flakes and small-sized CB nanoparticles, a low filler loading of 7.7 vol% (15 wt%) yielded the graphite-CB/UHMWPE composites with a satisfactory electrical conductivity of 33.9 S/m and a superior shielding effectiveness of 40.2 dB, manifesting the comparable value of the pricey large-aspect-ratio carbon nanofillers (e.g., carbon nanotubes and graphene nanosheets) based polymer composites. More interestingly, with the addition of 15 wt% graphite-CB (1/3, W/W) hybrid fillers, the tensile strength and elongation at break of the composite reached 25.3 MPa and 126%, respectively; with a remarkable increase of 58.1% and 2420% over the conventional segregated graphite/UHMWPE composites. The mechanical reinforcement could be attributed to the favor of the small-sized CB particles in the polymer molecular diffusion between UHMWPE domains which in turn provided a stronger interfacial adhesion. This work provides a facile, green and affordable strategy to obtain the polymer composites with high electrical conductivity, efficient EMI shielding, and balanced mechanical performance.

Ti3C2 MXenes with Modified Surface for High-Performance Electromagnetic Absorption and Shielding in the X-Band.

Electromagnetic (EM) absorbing and shielding composites with tunable absorbing behaviors based on Ti3C2 MXenes are fabricated via HF etching and annealing treatment. Localized sandwich structure without sacrificing the original layered morphology is realized, which is responsible for the enhancement of EM absorbing capability in the X-band. The composite with 50 wt % annealed MXenes exhibits a minimum reflection loss of -48.4 dB at 11.6 GHz, because of the formation of TiO2 nanocrystals and amorphous carbon. Moreover, superior shielding effectiveness with high absorption effectiveness is achieved. The total and absorbing shielding effectiveness of Ti3C2 MXenes in a wax matrix with a thickness of only 1 mm reach values of 76.1 and 67.3 dB, while those of annealed Ti3C2 MXenes/wax composites are 32 and 24.2 dB, respectively. Considering the promising performance of Ti3C2 MXenes with the modified surface, this work is expected to open the door for the expanded applications of MXenes family in EM absorbing and shielding fields.

Thin and flexible multi-walled carbon nanotube/waterborne polyurethane composites with high-performance electromagnetic interference shielding

A type of lightweight and flexible multi-walled carbon nanotube (MWCNT)/waterborne polyurethane (WPU) composites is fabricated, which show superior shielding effectiveness (SE) of electromagnetic interference in the X-band even under the thin thickness of samples. The thickness values 0.05, 0.32 and 0.8 mm correspond to SE of 24, 49 and 80 dB, respectively. This attributes to the extremely high MWCNT loading up to 76 wt%. Moreover, the composites show much higher specific SE (up to 3408 dB cm2/g) than other carbon-based polymer composites with similar filler amount. Shielding mechanisms of the composites with wide ranges of MWCNT loadings are discussed based on the concentration, thickness and conductivity. High concentration of MWCNT/WPU composites at low thicknesses indicates higher capability of shielding by absorption compared to reflection, which is adverse to composites with relatively low MWCNT mass ratios. A comparison between experimental and theoretical SE results is made in detail based on observed microstructures by scanning electron microscopy. The MWCNT/WPU composite films fabricated on large-area polyimide and cloth substrates are also demonstrated.

Enhanced Electromagnetic Interference Shielding of Mg–Zn–Zr Alloy by Ce Addition

The effects of Ce addition on microstructure and electromagnetic interference (EMI) shielding response of Mg–6Zn–0.5Zr (ZK60) alloy have been investigated. Ce addition resulted in grain refinement and higher density of Mg–Zn–Ce and MgZn2 intermetallic particles in the alloy. In particular, this was substantially remarkable as the addition of Ce was up to 1.0 wt%. It is interesting to note that as-extruded ZK60 alloy with 1.0 wt% Ce addition exhibited an EMI shielding effectiveness (SE) exceeding 70 dB at the frequency range of 30–1,500 MHz, which was significantly higher than that of ZK60 alloy without Ce addition and reached the requirement of high protection. The superior SE was probably related to the increased reflection and multiple reflection of electromagnetic radiation induced by Ce addition. Direct artificial aging at 150 °C for 25 or 50 h led to a further increase of 7–10 dB in the SE of the alloy with 1.0 wt% Ce addition. The advantages of excellent shielding capacity and favorable mechanical strength make the Mg–Zn–Zr–Ce alloy an attractive shielding candidate material for a variety of technological applications.