Optimization of electromagnetic shielding of three-dimensional orthogonal woven hybrid fabrics in ku band frequency region by response surface methodology

Electromagnetic shielding (EMS) has become the necessity of the present era due to enormous expansion in electronic devices accountable to emit electromagnetic radiation. The principal target of this paper is to originate three-dimensional (3D) orthogonal fabrics with conductive hybrid weft yarn and to determine their electromagnetic shielding. DREF-III core-spun yarn using copper filament in the core and polyphenylene sulfide (PPS) fiber on the sheath and fabric constructed of such yarn has a promising electromagnetic shielding characteristic. Box–Behnken experimental design has been employed to prepare various samples to investigate the electromagnetic shielding efficiency of 3D orthogonal woven structures. The orthogonal fabric samples were tested in an electromagnetic Ku frequency band using free space measurement system (FSMS) to estimate absorbance, reflectance, transmittance, and electromagnetic shielding. The increase in copper core filament diameter and hybrid yarn linear density enhances the EMS of orthogonal fabric. Statistical analysis has been done to bring out the effect and interaction of various yarn and fabric variables on EMS. Metal filament diameter, orientation, sheath fibers percentage, and fabric constructional parameters significantly affected electromagnetic shielding efficiency. The inferences of this study can be applied in other 3D structures like angle interlock, spacer fabrics for curtains, and coverings for civilians and military applications.

Electroless plating process for the manufacture of radiation protection suits for pregnant woman: Effect of bending on its electromagnetic shielding performance

Multi-ion fabrics (especially silver ion fabrics) have special advantages as electromagnetic radiation, but the use of noble metals enhances its cost. Electroless nickel plating (EP-Ni) has great potential application in fabricating low-cost metallized material. Here, EP-Ni on pure cotton surface to fabricate radiation protection suits for pregnant woman was established to replace traditional protection suits with silver film. The active groups on the cotton/polyester blend fiber surface could absorb tin and palladium ions, acting as catalytic centers, which can catalyze the reduction of Ni2+ in the plating solution. Ni particle with (111) crystal plane preferential oriented crystal structure deposited on cotton surface with a coarse microstructure. The Ni deposited amount is about 19%. The fabricated material exhibited a shielding effectiveness of 29.5 dB. Studies also shown that bending has no negative effect on crystallinity and electrical property. But more bending times could lead to crack, which would decline electromagnetic shielding performance by 24%.

Effects of Composition on the Electromagnetic Wave Shielding/Absorption and Corrosion in Zn-Ni Alloy Thin Film

In the Fourth industrial age, there is increasing use of electronic devices with high frequency (GHz) operating circuits for radio wave transmission/reception. This can lead to electromagnetic noise, and malfunctions in nearby devices. Electromagnetic shielding technology has emerged as an important way of preventing device malfunctions due to noise, and interest in shielding materials for electromagnetic waves has also increased. To allow compact integration and light weight electronic devices, highly efficient, thin and multifunctional film materials are required. This study selected the Zn-Ni alloy, which has adequate corrosion resistance, to protect the metal parent material of electronic components. Various compositions of the alloy were deposited using magnetron sputtering. Phase formation and composition were confirmed through XRD and SEM and EDS. The surface resistance of the thin films was measured using the 4point probe method, to calculate the shielding rate of the thin films. The electromagnetic wave shielding/absorption rate then measured according to frequency and the results compared with the calculated values. Corrosion resistance was evaluated with a polarization test. The far field electromagnetic shielding/absorption rate increased as the Zn content increased, up to 52 dB in a film with 70 at% of Zn. Corrosion resistivity behavior was the opposite. However, the Ni5Zn21 phase formation, which occurred in films with lower Zn composition, helped to improve electromagnetic absorption in the near field as well as corrosion resistivity. Therefore, the optimum composition of the Zn-Ni films was provisionally determined to be around Ni: Zn = 43:57 for electronic devices using electromagnetic waves in the near field range.

Design of a Lightweight Multilayered Composite for DC to 20 GHz Electromagnetic Shielding

The work aims to design a trilayer composite dedicated to electromagnetic shielding over a large frequency range, from 1 Hz to 20 GHz. Analytical and numerical models are used to determine the shielding effectiveness (SE) of this composite in the case of a planar shield. The shield is constituted of a support layer, a magnetic layer, and a conductive layer. Two possible designs are considered. To simplify the numerical calculation, a homogenization method and the Artificial Material Single Layer (AMSL) method are used. The proposed composite shows a good shielding capacity over the whole studied frequency range, with shielding effectiveness higher than 17 dB and 75 dB, respectively, in the near-field (1 Hz–1 MHz) and far-field (1 MHz–20 GHz). Both homogenization and AMSL methods show good suitability in near-field and allow one to greatly reduce the calculation time.