scholarly journals Microstructures and electromagnetic interference shielding effectiveness of ME21/Mg laminated materials by accumulative roll bonding

2021 ◽  
Author(s):  
Wanshun Zhang ◽  
Wenkai Zhang ◽  
Hongyang Zhao ◽  
Xiaodong Hu ◽  
Ming Chen ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electromagnetic Interference ◽  
Accumulative Roll Bonding ◽  
Electromagnetic Waves ◽  
Secondary Phase ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Multiple Reflections ◽  
Roll Bonding ◽  
Laminated Materials

Abstract Laminated composite with multi-layer interfaces has better electromagnetic interference shielding performance, which has attracted great attention. In this work, magnesium matrix laminated structure materials were prepared through Accumulative Roll Bonding (ARB). Microstructure, electrical conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of ME21/Mg laminated materials were investigated to understand the effect of layered structure and the change of microstructure on the electromagnetic shielding property. The results showed: the precipitated secondary phase and introduced interfaces could provide multiple reflections, attenuate the electromagnetic waves and improve the SE value. The electrical conductivity of 2-cycle increased to 21.04*106S/m，which was 17.74% higher than that of ME21 alloy, the intensity of texture of ME21 layer increased with the rolling passes, which contributed to the improvement of the electrical conductivity as well as the attenuation of reflection. The layered composite exhibited better shielding effectiveness compared with the ME21, in the 8.2-12.4 GHz test frequency, the SE was 98-107dB. The shielding mechanism of layered materials was explained, which provided guiding for the efficient shielding of electromagnetic waves.

scholarly journals Interface Engineered Microcellular Magnetic Conductive Polyurethane Nanocomposite Foams for Electromagnetic Interference Shielding

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Guolong Sang ◽  
Pei Xu ◽  
Tong Yan ◽  
Vignesh Murugadoss ◽  
Nithesh Naik ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Magnetic Loss ◽  
Interfacial Polarization ◽  
Conductive Network ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Multiple Reflections ◽  
Conduction Loss ◽  
Composite Foams ◽  
Emi Se

Abstract Lightweight microcellular polyurethane (TPU)/carbon nanotubes (CNTs)/ nickel-coated CNTs (Ni@CNTs)/polymerizable ionic liquid copolymer (PIL) composite foams are prepared by non-solvent induced phase separation (NIPS). CNTs and Ni@CNTs modified by PIL provide more heterogeneous nucleation sites and inhibit the aggregation and combination of microcellular structure. Compared with TPU/CNTs, the TPU/CNTs/PIL and TPU/CNTs/Ni@CNTs/PIL composite foams with smaller microcellular structures have a high electromagnetic interference shielding effectiveness (EMI SE). The evaporate time regulates the microcellular structure, improves the conductive network of composite foams and reduces the microcellular size, which strengthens the multiple reflections of electromagnetic wave. The TPU/10CNTs/10Ni@CNTs/PIL foam exhibits slightly higher SE values (69.9 dB) compared with TPU/20CNTs/PIL foam (53.3 dB). The highest specific EMI SE of TPU/20CNTs/PIL and TPU/10CNTs/10Ni@CNTs/PIL reaches up to 187.2 and 211.5 dB/(g cm−3), respectively. The polarization losses caused by interfacial polarization between TPU substrates and conductive fillers, conduction loss caused by conductive network of fillers and magnetic loss caused by Ni@CNT synergistically attenuate the microwave energy.

Facile fabrication of ultrathin graphene film with ultrahigh electrical conductivity and superb electromagnetic interference shielding effectiveness

2021 ◽  
Vol 9 (1) ◽  
pp. 214-222
Author(s):  
Xiaojing Liu ◽  
Wenyu Wu ◽  
Bin Guo ◽  
Minghao Cui ◽  
Huaxin Ma ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Self Assembly ◽  
Electromagnetic Interference ◽  
Graphene Film ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Graphene Films ◽  
Facile Fabrication ◽  
Electromagnetic Interference Shielding Effectiveness

Graphene films prepared through a self-assembly of graphene oxide and its derivatives have been recently explored for electromagnetic interference (EMI) shielding applications.

scholarly journals Effect of moisture absorption and fiber orientation on electrical conductivity and electromagnetic interference shielding of carbon fiber reinforced bioplastic composites

2019 ◽  
Vol 33 (10) ◽  
pp. 1950082 ◽  
Author(s):  
Wahyu Solafide ◽  
Ri-Ichi Murakami
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fiber ◽  
Electromagnetic Interference ◽  
Moisture Absorption ◽  
Shielding Effectiveness ◽  
Hot Press ◽  
Electromagnetic Interference Shielding ◽  
Effect Of Moisture ◽  
Electromagnetic Interference Shielding Effectiveness ◽  
Emi Se

The aim of this study is to discuss the effect of moisture absorption on electrical conductivity and electromagnetic interference of the carbon fiber (CF) reinforced bioplastic composite. The composites were prepared by the hot press machine, and immersed in water for 20 and 40 days. The electrical conductivity measurements were carried out as a function immersed time. The electrical conductivity of CF with two layers is greater than that of one layer, because the electrical conductivity increases with increasing the volume filler of CF. The electrical conductivity slightly increases with increasing the immersion time. The EMI SE (electromagnetic interference shielding effectiveness) of the composite was examined with the frequency from 500 MHz to 2000 MHz. The EMI SE of the CF increases with increasing the content of the CF, and the EMI SE result of composite is around 50 dB to 60 dB. There is scarcely significant effect of orientation on composite on the EMI SE.

Synergistic effects of hybrid conductive fillers on the electrical properties of carbon fiber pultruded polypropylene/polycarbonate composites prepared by injection molding

2016 ◽  
Vol 51 (7) ◽  
pp. 1005-1017 ◽  
Author(s):  
Myung Geun Jang ◽  
Choonglai Cho ◽  
Woo Nyon Kim
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Carbon Fiber ◽  
Injection Molding ◽  
Electromagnetic Interference ◽  
Synergistic Effects ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Preparation Methods ◽  
Electromagnetic Interference Shielding Effectiveness

In this study, the effects of filler characteristics and composite preparation methods on the morphology, mechanical property, electrical conductivity, and electromagnetic interference shielding effectiveness of the polypropylene/polycarbonate (70/30, wt%)/hybrid conductive filler composites were investigated. Nickel-coated carbon fiber (NCCF) was used as main filler and TiO2, multi-walled carbon nanotube, and graphite were used as second fillers in the composites. The pultruded NCCF/polypropylene composite was used in the preparation of the polypropylene/polycarbonate/NCCF/second filler composites. The electrical conductivity and electromagnetic interference shielding effectiveness of the polypropylene/polycarbonate/NCCF/second filler composites were compared with the type of second filler. The superior value of electromagnetic interference shielding effectiveness was observed to be 51.6 dB (decibel) when the hybrid fillers such as NCCF (5.2 vol% or 20 wt%) and TiO2 (1.2 vol% or 5 wt%) were added in the polypropylene/polycarbonate (70/30) composite. The electrical properties of the polypropylene/polycarbonate (70/30)/NCCF/TiO2 composites was compared with the composite preparation methods, which were injection molding and screw extrusion. The results suggested that fiber length of the NCCF affected significantly to the electrical conductivity and electromagnetic interference shielding effectiveness of the polypropylene/polycarbonate (70/30)/NCCF/TiO2 composites.

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