共查询到20条相似文献，搜索用时 15 毫秒
1.
James R. Garcia Mark McCrystal Dominik Horváth Harneet Kaur Tian Carey Jonathan N. Coleman 《Advanced functional materials》2023,33(20):2214855
Piezoresistive nanocomposites are an important class of materials that allow the production of very sensitive strain sensors. Herein, a new class of piezoresistive nanocomposites prepared by mixing different types of 2D nanosheets is explored. In this way, three distinct types of nanocomposite are produced by mixing conducting and insulating nanosheets (graphene, Gr and boron nitride, BN), conducting and semiconducting nanosheets (graphene and tungsten diselenide, WSe2 or tungsten disulfide, WS2) as well as mixing two different types of conducting nanosheets (graphene and silver, Ag). For each nanocomposite type, a different dependence of composite conductivity on filler volume fraction is observed although all behaviors can be fully described by percolation theory. In addition, each composite type shows different piezoresistive properties. Interestingly, while the conductor insulator composites show the standard monotonic relationship between gauge factor and conductivity, both conductor:semi-conductor and conductor:conductor composites show very unusual behavior, in each case displaying a peak engage factor at the percolation threshold. In each case, percolation theory is used to develop simple equations for gauge factor as a function of both volume fraction and conductivity that fully describes all experimental data. This work expands the understanding of piezoresistive nanocomposites and provides a platform for the engineering of high-performance strain sensors. 相似文献
2.
简单介绍了碱性离子钯活化体系在PTH制程中的应用,通过正交试验优化PTH重要工艺参数。介绍了PTH常见故障及其排除方法,分析了多层线路板生产中去钻污段调整对化学沉铜过程的可能影响机理。阐述了PTH制程中去钻污对背光稳定性的贡献及传统PTH制程对高厚径比板件孔金属化过程的控制方向。 相似文献
3.
聚酰亚胺二十三层板的研究与生产 总被引：1，自引：0，他引：1
本文旨在通过对聚酰亚胺材料在多层印制电路板制造中的研究和实践,总结试制及量产过程中有关技术和工艺难点的解决方法,为生产更高技术难度的多层PCB板制作奠定基础。 相似文献
4.
高深宽比离子束刻蚀技术是实现碲镉汞红外焦平面探测器的关键工艺技术.国内应用最广泛的双栅考夫曼刻蚀机束散角较大,沟槽深宽比较低.针对Ar离子束刻蚀机,尝试了三种提高深宽比的方法:选择不同的光刻胶做掩模、改变刻蚀角度和使用三栅离子源,并通过扫描电子显微镜(SEM)观察了碲镉汞刻蚀图形的剖面轮廓并计算了深宽比.分析了这些工艺方法对刻蚀图形轮廓的影响,获得了一些有助于获得高深宽比的离子束刻蚀沟槽的实验结果. 相似文献
5.
Fei Pan Mingqiang Ning Zhenhua Li Dan Batalu Hongtao Guo Xiao Wang Hongjing Wu Wei Lu 《Advanced functional materials》2023,33(27):2300374
The high filler loading (FL) is a bottleneck in developing lightweight ferromagnetic microwave absorbers (MAs) for the actual applications. Sequential architecture design of MAs can induce strange physical behaviors due to the unique coupling-enhancement effect between functional units, providing a vast potential for achieving high microwave absorption performance. However, the FLs of current sequential MAs fail to be designed on demand because the strange dielectric-magnetic behaviors cannot be fulfilled. The influence of sequential architecture engineering on the macroscopic properties or microscopic loss mechanism still needs more exploration. Herein, based on four mesoscopic models (particles, chains, bundles, and fibers) of ferromagnetic functional units, a series of ferromagnetic MAs with different sequential architectures are prepared via a bottom-up self-assembly method. The fibrous samples exhibit the best microwave absorption performance (−51.3 dB, 4.12 GHz) at a breakthrough FL of 2 wt%, which is one order of magnitude less than other ferromagnetic MAs. Strange dielectric-magnetic behaviors, including negative permittivity and heterodromous chiral vortex, occur due to functional units with lateral and fibrous configurations. Further, four special models are established to reveal the microwave attenuation evolutionary mechanism. This study clarifies the relationship between sequential architecture and strange dielectric-magnetic behaviors, which provides new sight to understand microscopic electromagnetic loss mechanism. 相似文献
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Izzuddin Zaman Hsu‐Chiang Kuan Qingshi Meng Andrew Michelmore Nobuyuki Kawashima Terry Pitt Liqun Zhang Sherif Gouda Lee Luong Jun Ma 《Advanced functional materials》2012,22(13):2735-2743
A scalable approach for the mass production of chemically modified graphene has yet to be developed, which holds the key to the large‐scale production of stable graphene colloids for optical electronics, energy conversion, and storage materials, catalysis, sensors, composites, etc. Here, a facile approach to fabricating covalently modified graphene and its polymer nanocomposites is presented. The method involves: i) employing a common furnace, rather than a furnace installed with a quartz tube and operated in inert gas as required in previous studies, to treat a commercial graphite intercalation compound with thermal shocking and ultrasonication and fabricate graphene platelets (GnPs) with a thickness of 2.51 ± 0.39 nm that contain only 7 at% oxygen; ii) grafting these GnPs with a commercial, long‐chain surfactant, which is able to create molecular entanglement with polymer matrixes by taking advantage of the reactions between the epoxide groups of the platelets and the end amine groups of the surfactant, to produce chemically modified graphene platelets (m‐ GnPs); and iii) solution‐mixing m‐GnPs with a commonly used polymer to fabricate nanocomposites. These m‐GnPs are well dispersed in a polymer with highly improved mechanical properties and a low percolation threshold of electrical conductivity at 0.25 vol%. This novel approach could lead to the future scalable production of graphene and its nanocomposites. 相似文献
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本文对用于X光激光实验的离轴式线聚焦光学系统作了详细的理论与实验研究。该系统已成功地用于“星光Ⅱ”激光装置的X光激光实验研究,取得了良好的结果。 相似文献
10.
The effect of thermal history on the electrical resistivity of a typical isotropic conductive adhesive (ICA) composed of an
epoxy-based binder has been investigated in the present work. The electrical resistivities of test specimens were found to
be different depending on the curing temperature, even if they exhibited similar degrees of conversion, although the values
of T
g
for the ICA specimens were determined by their degree of conversion, regardless of the curing temperature. Postannealing
effects in terms of decreased electrical resistivity could be induced at a temperature in the vicinity of the glass transition
temperature (T
g
), even if the specimens already achieved full conversion during the preliminary curing process. The magnitude of the annealing
effect was found to depend on the preliminary curing and postannealing temperatures. When the specimens exhibit conversions
of greater than 25% prior to the postannealing process, the preliminary curing state of the binder can influence the electrical
resistivity of the ICA that is obtained after annealing. 相似文献
11.
Nadia Grossiord Joachim Loos Lucas van Laake Maryse Maugey Cécile Zakri Cor E. Koning A. John Hart 《Advanced functional materials》2008,18(20):3226-3234
We present a detailed study of the influence of carbon nanotube (CNT) characteristics on the electrical conductivity of polystyrene nanocomposites produced using a latex‐based approach. We processed both industrially‐produced multi‐wall CNT (MWCNT) powders and MWCNTs from vertically‐aligned films made in‐house, and demonstrate that while the raw CNTs are individualized and dispersed comparably within the polymer matrix, the electrical conductivity of the final nanocomposites differs significantly due to the intrinsic characteristics of the CNTs. Owing to their longer length after dispersion, the percolation threshold observed using MWCNTs from vertically‐aligned films is five times lower than the value for industrially‐produced MWCNT powders. Further, owing to the high structural quality of the CNTs from vertically‐aligned films, the resulting composite films exhibit electrical conductivity of 103 S m?1 at 2 wt% CNTs. On the contrary, composites made using the industrially‐produced CNTs exhibit conductivity of only tens of S m?1. To our knowledge, the measured electrical conductivity for CNT/PS composites using CNTs from vertically‐aligned films is by far the highest value yet reported for CNT/PS nanocomposites at this loading. 相似文献
12.
实现高标清同播和素材共享必须对视频进行画幅变换。在分析AFD标准的特点、MXF文件的结构与数据封装方法的基础上,提出了一种在MXF文件中嵌入采用AFD标准描述符的幅型变换信息的方法,该方法将AFD数据作为元数据,依照MXF文件中元数据的扩展规范,实现了画幅变换信息与素材数据的绑定。 相似文献
13.
文章在PCB蚀刻理论的基础上,对蚀刻过程进行了流体力学分析,分析了不同纵横比线间药水流动情况,以及纵横比与药水流动、扩散层厚度变化的关系等,并通过试验进行了验证,可为业界精细线路蚀刻制作提供一定价值的参考和借鉴。 相似文献
14.
Pasquale F. Fulvio Richard T. Mayes Xiqing Wang Shannon M. Mahurin John C. Bauer Volker Presser John McDonough Yury Gogotsi Sheng Dai 《Advanced functional materials》2011,21(12):2208-2215
Mesoporous carbon materials do not have sufficient ordering at the atomic scale to exhibit good electronic conductivity. To date, mesoporous carbons having uniform mesopores and high surface areas have been prepared from partially‐graphitizable precursors in the presence of templates. High temperature thermal treatments above 2000 °C, which are usually required to increase conductivity, result in a partial or total collapse of the mesoporous structures and reduced surface areas induced by growth of graphitic domains, limiting their applications in electric double layer capacitors and lithium‐ion batteries. In this work, we successfully implemented a “brick‐and‐mortar” approach to obtain ordered graphitic mesoporous carbon nanocomposites with tunable mesopore sizes below 850 °C without using graphitization catalysts or high temperature thermal treatments. Phenolic resin‐based mesoporous carbons act as mortar to highly conductive carbon blacks and carbon onions (bricks). The capacitance and resistivity of final materials can be tailored by changing the mortar to brick ratios. 相似文献
15.
A novel, polymer-based carbon nanotube (CNT) composite with high electromagnetic (EM) wave shielding effectiveness (SE) and
high mechanical properties was developed. Two types of CNTs with different aspect ratios and morphologies are compared in
this study. Amorphous carbon and graphite powder are used as reference materials. The liquid crystal polymer (LCP) and melamine
formaldehyde (MF) are used as polymer matrices to study the orientation effect of CNTs in a polymer matrix. The influences
of orientation, aspect ratio, mass fraction, and morphology of CNTs upon the shielding effectiveness (SE) of CNT/polymer composites
are investigated. The experimental results show that the higher the orientation, the aspect ratio, and the weight percentage
of nanomaterials are in the composite, the higher the polymer composites’ SE. The nanomaterials’ morphology, especially CNTs,
also affects the SE value of the polymer composite. The highest SE for the CNT/LCP composite obtained is >62 dB. The theoretically
calculated SE data are consistent with experimentally obtained data. 相似文献
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17.
脉冲电镀在微盲孔填孔上的应用 总被引：4，自引：1，他引：4
电子产品的轻薄短小的发展趋势要求印制线路板的布线密度越来越高,这就使得板上的孔(包括通孔、埋孔和盲孔)径必须越来越小。在导通盲孔上直接叠孔的结构是实现最高布线密度的有效方法之一。作者通过水平脉冲电镀进行了微盲孔填孔电镀实验,在最佳的工艺条件下,在厚径比达到1.4:1的情况下仍然获得了良好的填孔效果,并对影响微盲孔填孔能力的一些因素进行了初步的探讨。 相似文献
18.
Renhui Sun Hao‐Bin Zhang Ji Liu Xi Xie Rui Yang Yue Li Song Hong Zhong‐Zhen Yu 《Advanced functional materials》2017,27(45)
Highly conductive polymer nanocomposites are greatly desired for electromagnetic interference (EMI) shielding applications. Although transition metal carbide/carbonitride (MXene) has shown its huge potential for producing highly conductive films and bulk materials, it still remains a great challenge to fabricate extremely conductive polymer nanocomposites with outstanding EMI shielding performance at minimal amounts of MXenes. Herein, an electrostatic assembly approach for fabricating highly conductive MXene@polystyrene nanocomposites by electrostatic assembling of negative MXene nanosheets on positive polystyrene microspheres is demonstrated, followed by compression molding. Thanks to the high conductivity of MXenes and their highly efficient conducting network within polystyrene matrix, the resultant nanocomposites exhibit not only a low percolation threshold of 0.26 vol% but also a superb conductivity of 1081 S m?1 and an outstanding EMI shielding performance of >54 dB over the whole X‐band with a maximum of 62 dB at the low MXene loading of 1.90 vol%, which are among the best performances for electrically conductive polymer nanocomposites by far. Moreover, the same nanocomposite has a highly enhanced storage modulus, 54% and 56% higher than those of neat polystyrene and conventional MXene@polystyrene nanocomposite, respectively. This work provides a novel methodology to produce highly conductive polymer nanocomposites for highly efficient EMI shielding applications. 相似文献
19.
Sining Wang Linlin Zhang Tao Hong Lizhong Su Yi Wen Bingchao Qin Yu Xiao Yuping Wang Haonan Shi Junqing Zheng Yuting Qiu Li-Dong Zhao 《Advanced functional materials》2024,34(4):2310335
BiSbSe3 is a Te-free thermoelectric material with intrinsically low thermal conductivity. Its thermoelectric performance is limited by poor electrical conductivity. To optimize electrical conductivity, Bi2SbSe3 with high carrier concentration and mobility is introduced to BiSbSe3 matrix through in situ reaction and conventional mechanical mixing. In both methods, carrier concentrations are improved by carrier injection and redistribution. Carrier mobility is manipulated based on microstructure. In the conventional method, isolated flake-shaped Bi2SbSe3 grains with weak-bonding phase boundaries restrict carrier mobility. For the in situ method, irregular Bi2SbSe3 connects into conductive networks inducing a percolation effect, and in situ formed small-angle phase boundaries barely impede carriers. Thus, the carrier mobilities of in situ composites are significantly improved and higher than that of conventional composites. Simultaneously optimized carrier concentration and mobility remarkably enhance electrical conductivity over the whole working temperature. Maximum electrical conductivity of 378 S cm−1 is achieved in BiSbSe3-38 vol% Bi2SbSe3 in situ composites at 300 K, obtaining more than 300% improvement compared with 124 S cm−1 in BiSbSe3 matrix. Lattice thermal conductivity is reduced at a low compositing fraction. Ultimately, a record-breaking average ZT of 0.65 (300–750 K) is attained in BiSbSe3-13 vol% Bi2SbSe3 in situ composite. The in situ compositing method in this work effectively optimizes electrical performance, anticipated to be applied in other thermoelectric materials. 相似文献
20.
The Hamiltonian of a quantum rod with an ellipsoidal boundary is given after a coordinate transformation which changes the ellipsoidal boundary into a spherical one. We then study the first internal excited state energy, the excitation energy and the frequency of the transition spectral line between the first internal excited state and the ground state of the strong-coupling polaron in a quantum rod. The effects of the electron–phonon coupling strength, the aspect ratio of the ellipsoid, the transverse radius of quantum rods and the transverse and longitudinal effective confinement length are taken into consideration by using a linear combination operator and the unitary transformation methods. It is found that the first internal excited state energy, the excitation energy and the frequency of the transition spectral line are increasing functions of the electron–phonon coupling strength, whereas they are decreasing ones of the transverse radius of quantum rods and the aspect ratio. The first internal excited state energy, the excitation energy and the frequency of the transition spectral line increase with decreasing transverse and longitudinal effective confinement length. oindent 相似文献