电磁屏蔽涂料用复合型导电填料研究进展

回顾了电磁屏蔽涂料用复合导电填料的现状和应用,并对比了各种类型复合导电填料的优缺点,重点阐述了复合碳纤维用作导电填料的优缺点及其应用。针对目前该类型填料高反射低吸收、分散性和亲和性等方面的不足,提出了解决方案。最后分析了复合型导电填料设计的影响因素。     

Carbon fiber reinforced polymer metallization via a conductive silver nanowires polyurethane coating for electromagnetic shielding

For electromagnetic shielding in space environment, the metallization of carbon fiber reinforced polymer (CFRP) is required. A specific attention is paid due to the thermal expansion coefficient difference between substrate and metal coating. A surface metallization of a CFRP has been elaborated by electrodeposition. This study presents an original process based on an electrically conductive polymer coating elaborated from a polyurethane matrix filled with a low content of silver nanowires (<10%vol). A continuous and adherent deposit is obtained by an optimization of the electroplating parameters. A minimal volume fraction was determined at 3%vol associated with an applied current density estimated near 0.1 A/dm². The growth speed is 7 μm/h at 0.1 A/dm². The adhesion was checked in severe environmental conditions (−196 to 165°C). The effectiveness shielding obtained with this solution reaches an attenuation value higher than 90 dB between 1 and 26 GHz necessary for space communication applications.     

641125电磁屏蔽复合导电无酸PSA胶带的研制

以无酸丙烯酸酯系压敏胶为导电胶基体,苯二亚甲基二异氰酸酯（XDI）为交联剂,镍／银混合粉体为导电填料,制备了铜箔导电胶带。讨论了导电粒子的种类及其添加量、交联剂的用量、老化存放时间等对导电胶带的粘接性能、导电性能及电磁屏蔽性能的影响。结果表明,当镍银混合粉添加15％,交联剂用量25％,干胶厚度45μm时,制备的胶带综合性能良好。其粘接强度大于19N／25mm,体积电阻率为6×10^-3Ω·cm,电磁屏蔽效能大于90dB（频率从30-1500MHz）,且耐高温性能稳定。     

Infrared-transparent films based on conductive graphene network fabrics for electromagnetic shielding

Transparency in the infrared (IR) light region and high conductivity for electromagnetic (EM) shielding performance are contradicting properties for conventional window materials. It is challenging to explore a new class of materials with both IR transmittance and high electrical conductivity. Herein, middle-IR transmittance and EM-shielding performance are realized by graphene network fabrics (GNFs). GNFs are fabricated by chemical vapor deposition using copper mesh with different geometric constructions as the sacrificial substrate. The structure of GNFs endows the as-fabricated material high IR transmittance, good electrical conductivity, and EM-shielding efficiency. The grid parameter τ with regard to the square aperture and wire width exerts a profound effect on the EM-shielding performance. The highest EM-shielding efficiency is 12.86 dB at 10 GHz with a transmittance of 70.85% at 4500 nm. Meanwhile, the highest IR light transmittance is 87.85% with an EM-shielding efficiency of 4 dB. Based on the experimental and theoretical analyses, the EM-shielding efficiency is prominently dependent on microwave absorption.     

Electrically conductive and corrosion resistant MAX phases with superior electromagnetic wave shielding performance

MAX phases have emerged as promising corrosion-resistant electromagnetic interference (EMI) shielding materials. Herein, four MAX phases: Ti₃SiC₂, Ti₃AlC₂, V_0.5Cr_1.5AlC, and Nb₄AlC₃, were synthesized via solid–liquid reactions. The electrical conductivities of Ti₃SiC₂, Ti₃AlC₂, V_0.5Cr_1.5AlC, and Nb₄AlC₃ are 14.7 × 10³, 15.5 × 10³, 5.1 × 10³, 8.0 × 10³ S/cm, respectively, and the corresponding average EMI shielding effectiveness values in the frequency of 18–26.5 GHz are 53.9, 69.2, 19.4, and 29.0 dB, respectively. Most importantly, these MAX phases are highly corrosion resistant under acidic conditions. Despite the exposure to the acidic environment and a slight decrease in the electrical conductivity, the corroded MAX phases exhibited excellent EMI shielding properties compared to the pristine MAX phases. Additional analysis showed that reflection was the primary EMI blocking mechanism. The study offers a guide for designing MAX phase ceramics that exhibit high EMI shielding performance in corrosive environments.     

Improving the electrical and electromagnetic shielding properties of conductive silicon rubber filled with Ni-coated carbon fibre by magnetic field

In this work, the effects of magnetic field induction on electrical and electromagnetic shielding properties of conductive silicon rubbers (CSRs) filled with Ni-coated carbon fibres (Ni/CFs) have been investigated. When the magnetic field intensity is above the threshold value of 0.10?T during the vulcanisation, it is beneficial to their electrical property that the volume resistivity decreases from 48.7?Ω·cm to 1.57?Ω·cm, owing to the orientation alignment of Ni/CFs in CSRs filled with Ni/CFs (40?phr). Moreover, with the aids of magnetic field induction, the prepared CSRs with lower amount of Ni-CF filler can receive better electromagnetic shielding of 65?dB in 500?MHz–3?GHz, which reduce cost effectively. This vulcanisation process shows promises for various applications in power transmission and transformation industries.     

The effect of thermal stresses on the EMI (electromagnetic interference) shielding of conductive plastics

The electrical properties of a number of filled and coated plastics were examined after subjecting the materials to rigorous thermal cycling between −20 and 80°C. Filled compounds that obtained their conductivity through the addition of carbon based conductive fillers maintained their conductivity throughout the thermal cycling. Compositions which contained metal fillers were able to maintain their conductivity only when a high temperature thermally stable polymer was used as the polymer matrix. Plaques coated by a zinc arc spray or with acrylic paints containing graphite, silver, and nickel particles were unaffected by thermal cycling. Plaques coated with an acrylic paint containing copper particles lost most of their conductivity during the changes in sample temperature.     

Anticorrosion and electromagnetic interference shielding behavior of candle soot-based epoxy coating

This article presents candle soot (CS) as anticorrosion coating material for mild steel (MS) in 3.5 wt % of NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy. CS is easily available, low-cost material, and characterized by using X-Ray diffraction (XRD), Raman spectroscopy, UV–vis spectroscopy, Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM). CS is superhydrobhobic in nature that helps to prevent corrosion by repelling water molecules from MS surface. The electrochemical results confirmed the prevention in corrosion process for MS using candle soot-epoxy (CS-EP) based anticorrosion coatings. The CS-based coatings displayed outstanding barrier properties in 3.5 wt % of NaCl solution in comparison to the neat EP coating. Different candle CS-EP coating combinations were tested that exhibited excellent corrosion inhibition performance with highest protection increased up to 98.45% at 0.2 wt % of CS. The surface morphological studies were used to analyze the MS surface conditions in absence and presence of CS-EP coating in 3.5 wt % of NaCl solution. CS-EP admixtures were also tested for their shielding effectiveness in the frequency range of 8.2–12.4 GHz and it has been found that on incorporation of 0.2 wt % of CS in EP resin total shielding effectiveness (SE_T) increased to −5.3 dB as compared to −0.33 dB for neat EP. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48675.     

镀银铜粉导电涂料的制备及性能

采用自制的镀银铜粉制备了导电涂料,研究了导电填料的用量和涂层厚度对涂层导电性的影响,以及导电涂层的抗电迁移和老化性能.结果发现,导电涂层的电阻率随导电填料的用量及涂层厚度的增加而逐渐下降,然后趋于平缓.适宜的镀银铜粉的用量为60％,涂层厚度为120 μm.在100℃以内,涂层具有良好的导电性;超过100℃后,涂层电阻率急剧增大,导电性下降.含镀银铜粉的涂层较含纯银粉涂层具有明显的抗电迁移性.     

Fine-grained and electrically conductive NdB6/SiO2: A promising electromagnetic interference shielding material with good thermal and mechanical properties

Searching for thermal conductive materials with high electromagnetic interference (EMI) shielding effectiveness (SE) is the key to protect electronic equipment against electromagnetic pollution and excess heat emission. Herein, NdB₆/SiO₂ bulks with high EMI SE and thermal conductivity which also exhibit good mechanical properties were prepared by liquid phase sintering (LPS). The NdB₆/SiO₂ bulk prepared by LPS at 1550 °C has fine grain-size, which is beneficial to improving mechanical property and EMI shielding performance. It exhibits high conductivity of 1.47 × 10⁴ S/cm, high EMI SE of 55.1 dB in K band, and high thermal conductivity of 37.9 W/m K. It also possesses flexural strength of 266 MPa and Vickers hardness of 14.8 GPa. Thus, NdB₆/SiO₂ composite ceramics are promising candidates for EMI shielding with good heat dissipation and mechanical load-bearing capabilities.     

Synthesis and properties of electromagnetic wave shielding polymer materials with low flammability

Novel polyethylene‐ and polypropylene‐based electromagnetic wave shielding and absorbing composite materials with low combustibility, enhanced thermal and mechanical properties, containing graphite, grinded wood, and fire retardants, were developed and investigated. Flame‐resistance, thermal and mechanical properties of these materials was investigated. Electromagnetic wave reflection coefficients over the frequency range 20–40 GHz were measured; at moderate concentration (10–15%) of functional filler, reflection coefficient can be as low as ?16 dB for PE and ?11 dB for PP composite, respectively. Coke formation mechanism was investigated, the principal role in this process is attributed to aromatization and condensation of aromatic compounds with the formation of polycyclic aromatic systems, an important role of phosphoric acids in accelerating this process was found. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Highly conductive and flexible bilayered MXene/cellulose paper sheet for efficient electromagnetic interference shielding applications

In this work, a robust and flexible bilayered MXene/cellulose paper sheet with superhigh electrical conductivity was prepared via vacuum-assisted filtration and a subsequent hot-pressing process for electromagnetic interference (EMI) shielding applications. By tightly assembling few-layered MXene (f-Ti₃C₂T_x) on the cellulose substrate via hydrogen bonds, an effective and interconnected conductive network was constructed in the paper sheet, resulting in a high electrical conductivity of 774.6–5935.4 S m^?1 at various f-Ti₃C₂T_x loadings. The highly conductive MXene layer can promptly reflect a great amount of incident EM waves, a process which preceded the transmission of EM waves in the cellulose matrix. Owing to the highly efficient reflection-dominated EMI shielding mechanism, the resultant bilayered MXene/cellulose paper sheets exhibit excellent EMI shielding effectiveness of 34.9–60.1 dB and specific EMI shielding efficiency of 290.6–600.7 dB mm^?1. Moreover, the MXene/cellulose paper sheets demonstrated improved mechanical strength (up to 25.7 MPa) and flexibility due to the mechanical frame effect acted by the cellulose substrate. Consequently, the robust and flexible bilayered MXene/cellulose paper sheet is a promising candidate for application in next-generation electric devices.     

Facile preparation of light-weight biodegradable and electrically conductive polymer based nanocomposites for superior electromagnetic interference shielding effectiveness

Harmful electromagnetic radiations that are generated from different electronic devices could be absorbed by a light weight and mechanically flexible good electromagnetic interference (EMI) shielding polymer nanocomposite. On the other hand, different electronic wastes (“e-wastes”) which are generally polymer building materials generated from wastes of dysfunctional electronic devices are not naturally biodegradable. Our recent effort has been employed to produce bio-degradable EMI shielding polymer nanocomposite. For that purpose, we had prepared a 50:50 ratio polylactic acid/thermoplastic polyurethane polymer nanocomposite by mixing the conducting carbon black with the blend following the facile and industrially feasible solution mixing method. Morphological characterizations by scanning electron microscopy and transmission electron microscopy analysis revealed the co-continuous morphology of the neat blend as well as polymer nanocomposites with the preferential distribution of conductive filler on a particular polymer phase. The polymer nanocomposites gave good mechanically with improved thermal properties. We got EMI shielding effectiveness around −27 dB with a low percolation threshold at around 30 wt% filler loading in the polymer nanocomposite at the X-band frequency domain (8.2–12.4 GHz). Later we had studied the biodegradability of the PLA/TPU along with their composites (T_XP_XC_X) by employing the respirometry method and got a satisfactory result to ensure their biodegradability.     

镀银铝粉填充型电磁屏蔽硅橡胶的制备与性能

研究了镀银铝粉填充量和环境试验对电磁屏蔽硅橡胶电学和力学性能的影响。结果发现,镀银铝粉填充量为210份(质量)是电磁屏蔽硅橡胶的逾渗阈值;最佳的镀银铝粉填充量为230份(质量),此时电磁屏蔽硅橡胶的体积电阻率为6.75×10-3Ω.cm,拉伸强度为2.3MPa,扯断伸长率为571%,邵尔A硬度为65;镀银铝粉填充型电磁屏蔽硅橡胶具有较好的耐高低温和热空气老化性能,而耐盐雾性能较差。     

Development of highly conductive hybrid Ni-biocarbon-based polyvinyl alcohol composites for microwave shielding properties

In this study a highly flexible microwave shielding material was fabricated by solution casting method utilizing Nickel and biocarbon particles in PVA matrix and characterized for mechanical, magnetic, and microwave shielding properties. The main aim of this study was to prove the significant role of magnetic particles in electromagnetic interference (EMI) shielding along with conductive particles. The results show that the addition of Ni-biocarbon hybrid particle increases the shielding properties up to 56.5 dB at 20 GHz. The magnetic permeability increased gradually with the inclusion of Ni particles with a highest magnetization, coercivity, and retentivity of 1250 E⁻⁶ emu, −9000 G, and 1100 E⁻⁶ emu. Similarly the mechanical results show that adding biocarbon enhances the composite's mechanical properties. A highest tensile strength, tear strength, elongation, and hardness are noted as 38, 168 MPa, 18.4%, and 36 Shore-D. Comparatively, the hardness and elongation% of composite designations contains 3 and 5 vol% of hybrid particles have increased by 9% and 26%, respectively, in comparison to composite containing only 5 vol% of biocarbon with PVA. Scanning electron microscope fractography indicates biocarbon particles reduce voids and improve adhesion. These flexible EMI shielding composites could be used in telecommunication and other wave transmitting devices in engineering applications.     

Magneto-dielectric and magneto-conducting fillers based polymer composites: Effect of functionalization,coating and dispersion process on electromagnetic shielding properties

Electromagnetic interference shielding of magneto-dielectric (BaTiO₃-Fe₃O₄) and magneto-conducting (f-MWCNT-Fe₃O₄) fillers based polymer electrolyte composites in the X-band have been studied in the present work. Magneto-dielectric and magneto-conducting fillers have been obtained by in situ preparation of Fe₃O₄ nanoparticles by chemical precipitation in the presence of BaTiO₃ and functionalized multiwalled carbon nanotubes (f-MWCNT). Functionalization of MWCNT has resulted in their strong bonding with the polymer electrolyte adversely affecting the charge transport properties and shielding effectiveness. Dielectric, magnetic and conducting properties of the magneto-dielectric and magneto-conducting fillers are found to be significantly different as a result of coating by Fe₃O₄ nanoparticles on BaTiO₃ and f-MWCNT. Combining two fillers in a single nanocomposite has exhibited non-complimentary addition of their individual properties. The ultra-sonication method of dispersion of the magneto-conducting filler has been found to give better conducting and shielding effectiveness in comparison to the homogenization method due to better disentanglement of the nanotubes.     

PET表面金属银涂层的制备与性能

以聚对苯二甲酸乙二酯(PET)为基体,基于化学刻蚀和敏化处理的表面改性,采用双组分喷涂法在改性基体表面制备了高性能的银涂层.改变喷涂过程中银氨溶液和还原溶液的浓度以及喷涂次数,研究它们对银涂层的微观形貌、宏观形貌、沉积量和光学常数的影响,考察了最佳喷涂条件下所得银涂层的成分和性能.结果表明:化学刻蚀后表面产生大量凹坑,...