水性电磁屏蔽涂料的开发与应用

本文采用炭黑、石墨粉和石墨烯为导电材料调配出一种水性电磁屏蔽涂料,可做内墙底漆使用,对水泥、砂浆、腻子、石膏、砖石均有较强的附着力,电磁屏蔽涂料的最佳配方为:导电浆料∶粘合剂基料=70%∶30%,石墨烯∶炭黑∶石墨粉=40%∶30%∶30%。经权威部门测试,在0.3 MHz～40 GHz频段的屏蔽效能40.1～62.3 dB;将水性电磁屏蔽涂料应用于屏蔽室施工中,实测涂料墙200 MHz～3.0 GHz频段的屏蔽效能42～48 dB,具备较好的屏蔽效果。     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41 dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41 dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。专业生产各种夹胶玻璃(普通白玻、超白玻璃、镀膜玻璃、钢化玻璃、防火玻璃等),     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41 dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。专业生产各种夹胶玻璃(普通白玻、超白玻璃、镀膜玻璃、钢化玻璃、防火玻璃等),     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41 dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。专业生产各种夹胶玻璃(普通白玻、超白玻璃、镀膜玻璃、钢化玻璃、防火玻璃等),     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。专业生产各种夹胶玻璃(普通白玻、超白玻璃、镀膜玻璃、钢化玻璃、防火玻璃等),     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41 dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。专业生产各种夹胶玻璃(普通白玻、超白玻璃、镀膜玻璃、钢化玻璃、防火玻璃等),     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41 dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。专业生产各种夹胶玻璃(普通白玻、超白玻璃、镀膜玻璃、钢化玻璃、防火玻璃等),     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41 dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。专业生产各种夹胶玻璃(普通白玻、超白玻璃、镀膜玻璃、钢化玻璃、防火玻璃等),     

秦皇岛玻璃工业研究设计院有限公司防辐射所

正专业生产各种电磁屏蔽玻璃制品,20 MHz～1 GHz屏蔽效能≥50 dB;1 GHz～1.5 GHz屏蔽效能≥41 dB,电磁波阻挡99%以上,光学透过率≥70%。长期为中国航空集团、中国电子集团、空军某师提供电磁屏蔽玻璃配件,产品合格率达到100%,完全满足客户使用要求。专业生产各种夹胶玻璃(普通白玻、超白玻璃、镀膜玻璃、钢化玻璃、防火玻璃等),     

Electromagnetic interference shielding reaching 70 dB in steel fiber cement

An electromagnetic interference (EMI) shielding effectiveness of 70 dB at 1.5 GHz has been attained in cement paste that contains 0.72 vol.% stainless steel fibers of diameter 8 μm and length 6 mm. The shielding is primarily by reflection. The material exhibits electrical resistivity 16 Ω cm. The presence of sand essentially does not affect the shielding effectiveness. The fibers remain effective in the presence of steel rebars. For comparison, the shielding effectiveness of a solid piece of stainless steel is 78 dB at 1.5 GHz.     

Strong and Flexible Carbon Fiber Fabric Reinforced Thermoplastic Polyurethane Composites for High‐Performance EMI Shielding Applications

Electromagnetic shielding materials play a significant role in solving the increasing environmental problem of electromagnetic pollutions. The commonly used metal‐based electromagnetic materials suffer from high density, poor corrosion resistance, and high processing cost. Polymer composites exhibit unique combined properties of lightweight, good shock absorption, and corrosion resistance. In this study, a novel high angle sensitive composite is fabricated by combining carbon fiber (CF) fabric with thermoplastic polyurethane elastomer (TPU). The effect of stacking angle of CF fabric on EMI shielding performance of composite is studied. When the stacking angle of CF fabric changed, the electromagnetic interference (EMI) shielding effectiveness (SE) of CF fabric/TPU composite can reach a maximum of 73 dB, and the tensile strength can reach 168 MPa. In addition, the composite has anisotropic conductivity, which is conductive along the plane direction and nonconductive along the thickness direction. Moreover, the CF fabric/TPU composite manifests exceptional EMI‐SE/density/thickness value of 383 dB cm² g^?1, which is higher than most of current EMI shielding composites reported in literature. In summary, CF fabric/TPU composite is an excellent EMI shielding material that is lightweight, highly flexible, and mechanically robust, which can be applied to the field of aerospace and some intelligent electronic devices.     

Electroless nickel deposition of a palladium‐activated self‐assembled monolayer on polyester fabric

In this study, an alternative Pd activation process was developed for electroless Ni plating on polyester fabric modified with a self‐assembled monolayer (SAM) of 3‐aminopropyltrimethoxysilane (APTMS). The presence of a highly oriented amino‐terminated SAM and the formation of Pd‐activated APTMS were demonstrated by X‐ray photoelectron spectroscopy analysis. After activation, electroless Ni plating was successfully initiated, and the Ni coating was deposited onto the surface of the polyester fibers. The resulting Ni coating was examined by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray diffraction. The electromagnetic interference (EMI) shielding effectiveness (SE) and adhesive strength of the Ni‐plated polyester fabric were evaluated. On the basis of the experimental results, the Ni coating produced with a Pd‐activated SAM was uniform and dense. As the Ni weight on the treated fabric was 32 g/m², the EMI SE of the Ni‐plated polyester fabric modified with APTMS obtained was more than 30 dB at frequencies that ranged from 2 to 18 GHz. Compared with the conventional two‐step activation method, Ni coating on the Pd‐activated polyester fabric modified with APTMS improved the coating adherence stability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Flexible and Highly Conductive AgNWs/PEDOT:PSS Functionalized Aramid Nonwoven Fabric for High-Performance Electromagnetic Interference Shielding and Joule Heating

High-performance multifunctional textiles are highly demanded for human health-related applications. In this work, a highly conductive nonwoven fabric is fabricated by coating silver nanowires (AgNWs)/poly(3,4-ethyl enedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on a poly(m-phenylene isophthalamide) (PMIA) nonwoven fabric through a multistep dip coating process. The as-prepared PMIA/AgNWs/PEDOT:PSS composite nonwoven fabric shows an electrical resistance as low as 0.92 ± 0.06 Ω sq⁻¹ with good flexibility. The incorporation of the PEDOT:PSS coating layer improves the adhesion between AgNWs and PMIA nonwoven fabric, and also enhances the thermal stability of the composite nonwoven fabric. Electromagnetic interference (EMI) shielding and Joule heating performances of the PMIA/AgNWs/PEDOT:PSS composite nonwoven fabric are also investigated. The results show that the average EMI shielding effectiveness (SE) of the single-layer nonwoven fabric in X-band is as high as 56.6 dB and retains a satisfactory level of SE after being washed, bended, and treated with acid/alkali solution and various organic solvents. The composite nonwoven fabric also exhibits low voltage-driven Joule heating performance with reliable heating stability and repeatability. It can be envisaged that the multifunctional PMIA/AgNWs/PEDOT:PSS nonwoven fabric with reliable stability and chemical robustness can be used in EMI shielding devices and personal thermal management products.     

Modeling for the electromagnetic properties and EMI shielding of Cf/mullite composites in the gigahertz range

The electromagnetic properties and EMI shielding effectiveness of C_f/mullite composites via the spark plasma sintering were intensively investigated in the gigahertz range (8.2–12.4 GHz). Experimental results have revealed excellent electromagnetic properties and a high value of EMI shielding effectiveness (nearly 40 dB) for C_f/mullite composites with 1.65 vol% carbon fillers at thickness of 2 mm. We quantitatively characterize the contributions of microstructural features to overall EMI shielding effectiveness using a micromechanics-based homogenization model. The EMI shielding effectiveness enhances with respect to the C_f volume concentration before the threshold. The increasing trend of EMI shielding effectiveness with respect to AC (alternating current) frequency can be attributed to enhanced conductivity at high gigahertz range. It is demonstrated that filler and frequency dependent interface effects are essential to obtain excellent electromagnetic properties of C_f/mullite composite. The present research can provide guidances for the design of ceramic-based composites applied in high-temperature EMI shielding devices.     

Comparison of polyelectrolyte and sodium dodecyl benzene sulfonate as dispersants for multiwalled carbon nanotubes on cotton fabrics for electromagnetic interference shielding

Cotton fabrics with multiwalled carbon nanotubes (MWCNTs) dispersed by Nafion, a polyelectrolyte, and sodium dodecyl benzene sulfonate (SDBS), a surfactant, were prepared for electromagnetic interference (EMI) shielding. The fabrics were characterized by scanning electron microscopy and vector network analysis. The fabrics with the Nafion–MWCNT coating possessed a better shielding efficiency (SE) than those with the SDBS–MWCNT coating because of a more uniform dispersion of MWCNTs, which improved the electrical conductivity and EMI shielding properties. The maximum SE value of the fabric reached 11.48 dB, and the specific SE was 39.6 dB cm³/g. The reflectivity and absorptivity were calculated separately to determine the main mechanism of EMI shielding. The absorptivity was 68.6% at 12 GHz for the Nafion–MWCNT‐coated fabric; this showed that the dominant mechanism of EMI shielding for the treated fabrics was absorption. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40588.     

Improved Electromagnetic Interference Shielding Properties of MWCNT–PMMA Composites Using Layered Structures

Electromagnetic interference (EMI) shielding effectiveness (SE) of multi-walled carbon nanotubes–polymethyl methacrylate (MWCNT–PMMA) composites prepared by two different techniques was measured. EMI SE up to 40 dB in the frequency range 8.2–12.4 GHz (X-band) was achieved by stacking seven layers of 0.3-mm thick MWCNT–PMMA composite films compared with 30 dB achieved by stacking two layers of 1.1-mm thick MWCNT–PMMA bulk composite. The characteristic EMI SE graphs of the composites and the mechanism of shielding have been discussed. SE in this frequency range is found to be dominated by absorption. The mechanical properties (tensile, flexural strength and modulus) of the composites were found to be comparable or better than the pure polymer. The studies therefore show that the composite can be used as structurally strong EMI shielding material.     

Electrical conductivity and electromagnetic interference shielding of polyaniline/polyacrylate composite coatings

Lightweight and flexible composite coatings of p‐toluene sulfonic acid doped polyaniline (PANI–TSA) with various mass fractions and polyacrylate were prepared for electromagnetic interference (EMI) shielding. Both the volume and surface conductivities of the composite coatings increased with increasing PANI–TSA; furthermore, the volume conductivity showed a typical percolation behavior with a percolation threshold at about 0.21. The EMI shielding effectiveness (SE) of the PANI–TSA/polyacrylate coatings over the range of 14 kHz to 15 GHz increased with increasing PANI–TSA as the direct‐current conductivity did. EMI SE of the coatings at the low frequencies (14 kHz to 1 GHz) was around 30–80 dB, higher than that at the high frequencies (1–15 GHz); this indicated possible commercial application of the coatings for far‐field EMI shielding. The highest EMI SE value was 79 dB at 200 MHz with a coating thickness of 70 ± 5 μm. The moderate SE, light weight, and easy preparation of the coating are advantages for future applications for EMI shielding. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2149–2156, 2005     

Electrical and Electromagnetic Interference (EMI) shielding properties of hexagonal boron nitride nanoparticles reinforced polyvinylidene fluoride nanocomposite films

The hexagonal boron nitride nanoparticles (h-BNNPs) reinforced flexible polyvinylidene fluoride (PVDF) nanocomposite films were prepared via a simple and versatile solution casting method. The morphological, thermal and electrical properties of h-BNNPs/PVDF nanocomposite films were elucidated. The electromagnetic interference (EMI) shielding properties of prepared nanocomposite films were investigated in the X-band frequency regime (8–12 GHz). The EMI shielding effectiveness (SE) was increased from 1 dB for the PVDF film to 11.21 dB for the h-BNNPs/PVDF nanocomposite film containing 25 wt% h-BNNPs loading. The results suggest that h-BNNPs/PVDF nanocomposite films can be used as lightweight and low-cost EMI shielding materials.     

木材单板表面化学镀镍

以杨木单板为原料,利用化学镀法在其表面镀覆N i-P合金镀层,以此来制备具有电磁屏蔽功能的木材-金属复合材料。用扫描电镜(SEM)、能谱分析仪(EDS)和X射线衍射仪(XRD)分析了镀层形貌、成分和镀层结构,研究了经表面化学镀N i-P合金后杨木单板的电磁屏蔽性能和表面导电性能。SEM分析表明,杨木单板经表面化学镀N i-P合金后,表面完全被镀层覆盖,金属感增强。EDS分析表明,镀层为N i-P合金镀层,其中磷含量较低,主要成分为镍。XRD分析结果表明,镀层为晶态结构。镀后杨木单板的表面电阻率很低,而电磁屏蔽效能较高,在9 kHz~1.5 GHz,可达到60 dB左右。