Electromagnetic Shielding Effectiveness of Nickel Fiber-Reinforced Cement Composites

2017 ◽  
Vol 898 ◽  
pp. 2065-2070 ◽  
Author(s):  
Wei Lin Yao ◽  
Guo Xuan Xiong ◽  
Ying Yang
Keyword(s):  
Electrical Conductivity ◽  
Composite Materials ◽  
Electromagnetic Shielding ◽  
Coaxial Cable ◽  
Frequency Change ◽  
Cement Composites ◽  
Fiber Reinforced ◽  
Shielding Effectiveness ◽  
Reinforced Cement ◽  
Electromagnetic Shielding Effectiveness

The nickel fiber was added into the cement-based composite materials as a shielding medium. Influences of the three different types and amount of dispersants and weight fraction of nickel fiber on the electrical conductivity and electromagnetic shielding effectiveness of the cement matrix composite were discussed. The conductivity of cement based composite materials and the uniformity distribution of shielding medium were characterized by four-point probe meter and scanning electron microscopy, respectively. Electromagnetic interference shielding effectiveness in the frequency range of 1 MHz to 1500 MHz was characterized by coaxial cable method. The results indicated that the improved dispersion of nickel by incorporation of dispersants might yield the enhancement of the electrical properties of nickel fiber-reinforced cement composites. When the dosage of methyl cellulose reaches 0.4 wt.%, the pre-dispersing nickel fiber enhances the electrical conductivity of the cement-based composite materials significantly. With the increase of fiber volume fraction, the shielding effectiveness and trend of frequency change of the corresponding fiber-reinforced concrete were enhanced. When the content of nickel fiber powder was 9.0 vol.%, the conductivity was 2.65×10-3 s·cm-1, and the average shielding effectiveness of the specimen in 1MHz-1500 MHz was about 21.78 dB, with the maximum shielding effectiveness of 24.48 dB and the minimum shielding effectiveness 19.85 dB.

scholarly journals Electromagnetic Shielding Effectiveness of Woven Fabrics with High Electrical Conductivity: Complete Derivation and Verification of Analytical Model

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1657 ◽  
Author(s):  
Marek Neruda ◽  
Lukas Vojtech
Keyword(s):  
Electrical Conductivity ◽  
Analytical Model ◽  
Electromagnetic Interference ◽  
Woven Fabrics ◽  
Electromagnetic Shielding ◽  
High Electrical Conductivity ◽  
Shielding Effectiveness ◽  
Textile Composite ◽  
A Value ◽  
Electromagnetic Shielding Effectiveness

In this paper, electromagnetic shielding effectiveness of woven fabrics with high electrical conductivity is investigated. Electromagnetic interference-shielding woven-textile composite materials were developed from a highly electrically conductive blend of polyester and the coated yarns of Au on a polyamide base. A complete analytical model of the electromagnetic shielding effectiveness of the materials with apertures is derived in detail, including foil, material with one aperture, and material with multiple apertures (fabrics). The derived analytical model is compared for fabrics with measurement of real samples. The key finding of the research is that the presented analytical model expands the shielding theory and is valid for woven fabrics manufactured from mixed and coated yarns with a value of electrical conductivity equal to and/or higher than σ = 244 S/m and an excellent electromagnetic shielding effectiveness value of 25–50 dB at 0.03–1.5 GHz, which makes it a promising candidate for application in electromagnetic interference (EMI) shielding.

Electrical Conductivity and Electromagnetic Shielding Effectiveness of CB/ABS Composites

2011 ◽  
Vol 675-677 ◽  
pp. 461-463
Author(s):  
Hai Ping Duan ◽  
Yu Ping Duan
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Mass Fraction ◽  
Acrylonitrile Butadiene Styrene ◽  
Volume Resistivity ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Percolation Effect ◽  
Electromagnetic Shielding Effectiveness ◽  
Butadiene Styrene

In this paper, the effects of carbon black (CB) mass fraction on volume resistivity and electromagnetic shielding effectiveness (SE) of CB/Acrylonitrile Butadiene Styrene (ABS) composites were studied. The results indicated that when CB mass fraction was over 15 wt%, the volume resistivity dropped sharply and when it rose to 35 wt%, the volume resistivity achieved the lowest value about 103Ω·cm. In addition, there are two obvious percolation effect at 15~20 wt% and 25~35 wt% CB respectively in the course of the volume resistivity changing. Titanate coupling agent could greatly improve conduction and SE of CB/ABS composites. Lastly, the SE of CB/ABS composites was investigated by experimental observation.

scholarly journals Electrical Conductivity and Electromagnetic Shielding Effectiveness of Bio-Composites

2020 ◽  
Vol 4 (1) ◽  
pp. 28
Author(s):  
Konstantinos Tserpes ◽  
Vasileios Tzatzadakis ◽  
Jens Bachmann
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Numerical Models ◽  
Experimental Testing ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Carbon Fiber Fabric ◽  
Electromagnetic Shielding Effectiveness ◽  
Fiber Fabric

In this paper, the electrical conductivity and electromagnetic shielding effectiveness of two bio-composites are studied by experimental testing and numerical models. Two monolithic composites with partly bio-based content were manufactured. The first bio-composite is made of a carbon fiber fabric prepreg and a partly bio-based (rosin) epoxy resin (CF/Rosin). The second bio-composite is a combination of prepregs of carbon fiber fabric/epoxy resin and flax fiber fabric/epoxy resin (CF-Flax/Epoxy). A single line infusion process was used prior to the curing step in the autoclave. Both variants are exemplary for the possibility of introducing bio-based materials in high performance CFRP. In-plane and out-of-plane electrical conductivity tests were conducted according to Airbus standards AITM2 0064 and AITM2 0065, respectively. Electromagnetic shielding effectiveness tests were conducted based on the standard ASTM D 4935-10. Materials were prepared at the German Aerospace Center (DLR), while characterization tests were conducted at the University of Patras. In addition to the tests, numerical models of representative volume elements were developed, using the DIGIMAT software, to predict the electrical conductivity of the two bio-composites. The preliminary numerical results show a good agreement with the experimental results.

The effects of fabric lamination angle and ply number on electromagnetic shielding effectiveness of weft knitted fabric-reinforced polypropylene composites

2014 ◽  
Vol 21 (1) ◽  
pp. 129-135 ◽  
Author(s):  
Devrim Soyaslan ◽  
Özer Göktepe ◽  
Selçuk Çömlekçi
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Copper Wire ◽  
Industrial Applications ◽  
Electromagnetic Shielding ◽  
Knitted Fabric ◽  
Shielding Effectiveness ◽  
Polypropylene Composites ◽  
Weft Knitted Fabric ◽  
Electromagnetic Shielding Effectiveness

AbstractIn this study, it was aimed to investigate the effects of fabric lamination angle and fabric ply number on electromagnetic shielding effectiveness (EMSE) of weft knitted fabric-reinforced polypropylene composites. Knitted fabric-reinforced composites are composed of aramid yarn, polypropylene yarn, and copper wire. Polypropylene is the matrix phase and the aramid yarn and copper wires are the reinforcement phase of the composite materials. It was achieved to form 1.5 to 3 mm thickness composites. The composites have nearly 20–50 dB electromagnetic shielding values. To form the knitted fabrics, 7G semiautomatic flat knitting machine was used. The composites were formed by a laboratory-type hot press. EMSE of composites were tested by using ASTM D 4935 coaxial test fixture in 27–3000 MHz frequency band. Lamination angle and ply number parameters were examined related to EMSE of structures. For this study, three different structures were knitted and named as plain knit, 1×1 rib knit, and half cardigan knit. To determine the effect of lamination angle of composites on electromagnetic shielding performance, the composites were produced in two different lamination angles as 0°/90°/0°/90° and 0°/45°/0°/45°. To determine the effect of fabric ply number of composites on electromagnetic shielding performance, the composites were produced in two and four plies. It was observed that the fabric ply number and lamination angle does not affect the EMSE of composite materials very much. It was determined that weft knitted reinforced composite structures have appropriate and high EMSE values for electromagnetic applications. This knitted fabric-reinforced polypropylene composites are flexible and suitable for other industrial applications as civil engineering, aerospace, etc.

Electromagnetic Shielding Effectiveness of Carbon Black -Carbon Fiber Cement Based Materials

2010 ◽  
Vol 168-170 ◽  
pp. 1438-1442 ◽  
Author(s):  
Shao Wen Huang ◽  
Guang Hua Chen ◽  
Qi Luo ◽  
Yu Hua Xu
Keyword(s):  
Carbon Fiber ◽  
Carbon Black ◽  
Mass Fraction ◽  
Electromagnetic Shielding ◽  
Cement Composites ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Cement Based Materials ◽  
Electromagnetic Shielding Effectiveness ◽  
Effective Additive

The electromagnetic shielding effectiveness (SE) of cement based composites filled with carbon black and carbon fiber were discussed in this paper. Results show the SE of cement composites will get obvious improvement as the carbon black mass fraction increases beyond 6%. Carbon fiber is a much more effective additive than carbon back. The shielding effectiveness were gradually improved with the increase of content of carbon fiber, the maximum attained 21 dB at 1.5GHz. Adding carbon black and carbon fiber, SE of the cement based materials get more upward gradient, the maximum SE reached 27 dB in tested frequency range.

scholarly journals Electromagnetic Shielding Effectiveness and Conductivity of PTFE/Ag/MWCNT Conductive Fabrics Using the Screen Printing Method

2020 ◽  
Vol 12 (15) ◽  
pp. 5899
Author(s):  
Hung-Chuan Cheng ◽  
Chong-Rong Chen ◽  
Shan-hui Hsu ◽  
Kuo-Bing Cheng
Keyword(s):  
Electrical Conductivity ◽  
Electromagnetic Interference ◽  
Electromagnetic Shielding ◽  
Multiwall Carbon Nanotube ◽  
Shielding Effectiveness ◽  
Ptfe Film ◽  
Conductive Films ◽  
Hybrid Grid ◽  
Electromagnetic Shielding Effectiveness ◽  
Mwcnt Loading

The management of the electromagnetic interference (EMI) of thin, light, and inexpensive materials is important for consumer electronics and human health. This paper describes the development of conductive films that contain a silver (Ag) flake powder and multiwall carbon nanotube (MWCNT) hybrid grid on a polytetrafluoroethylene (PTFE) film for applications that require electromagnetic shielding (EMS) and a conductive film. The Ag and MWCNT hybrid grid was constructed with a wire diameter and spacing of 0.5 mm. The results indicated that the proposed conductive films with 0.4 wt% MWCNTs had higher electromagnetic shielding effectiveness (EMSE) and electrical conductivity than those with other MWCNT loading amounts. The results also showed that the film with 0.4 wt% MWCNT loading had a high 62.4 dB EMSE in the 1800 MHz frequency and 1.81 × 104 S/cm electrical conductivity. This combination improved stretchability, with 10% elongation at a 29% resistivity change rate. Conductive films with Ag/MWCNT electronic printing or lamination technologies could be used for EMI shielding and electrically conductive applications.

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