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《中国电机工程学报》2016,(24)
我国高压直流输电技术的发展对电介质材料的绝缘性能提出了更高的要求,聚合物纳米电介质材料以其优异的性能而受到广泛的关注,其中的界面更成为研究热点。界面是纳米填料与聚合物基体之间的纳米级过渡区域,由于形成机理特殊,其具有不同于聚合物基体和纳米填料的独特性质。由于界面在复合材料中占有主导地位,其微观结构及性能将直接影响复合材料的宏观性能。该文综合国内外研究成果,介绍了界面的形成机理和结构模型,论述了界面区对聚合物聚集态结构的影响及陷阱理论,分析了界面在复合材料电学性能中的作用机理,最后探讨了利用静电力显微镜研究界面微区介电特性的技术方法。 相似文献
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聚酰亚胺/氧化硅/氧化铝纳米复合薄膜的制备及性能研究 总被引:3,自引:3,他引:0
通过正硅酸乙酯和甲基三乙氧基硅烷及异丙醇铝在聚酰胺酸的N,N-二甲基乙酰胺溶液中的溶胶凝胶反应,制备了具有一定SiO2和Al2O3质量百分含量的聚酰亚胺复合薄膜。并且分别利用原子力显微镜和傅立叶变换红外光谱对薄膜进行界面形态和微观结构分析。并讨论了无机组分对薄膜的热性能和电性能的影响。结果表明,聚酰亚胺复合薄膜中的无机组分的分散性良好,与聚酰亚胺基体形成了很好的纳米复合体系,经试验研究证明了无机组分的引入大大提高了薄膜的耐局部放电学性能和耐热性能。 相似文献
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将纳米BaTiO_3添加到以聚乙烯醇(PVA)为基体的聚合物电解质中,制备了复合聚合物电解质,通过SEM测试和交流阻抗等方法对聚合物电解质膜的物理性能和电化学性能进行了研究。结果表明,BaTiO_3复合的电解质具有更高的电导率,对复合聚合物电解质在动力电池上的发展前景进行了预测。 相似文献
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Conducting polymer composites become increasingly important for technical applications. In this article, the resulting electrical properties of such materials are illustrated by a variety of experimental examples. It is shown that the combined mechanical, thermal and electrical interaction between the filler particles via their electrical contacts and the surrounding polymer host matrix are responsible for the properties of the composite material. A short review is given of the theoretical background for the understanding of the electrical transport in such materials. The arrangement of the filler particles and the resulting conductivity can be described either by percolation or by effective medium theories. It can also be related to different types of charge carrier transport processes depending on the internal composite structure. Special emphasis is given to the microstructure of the filler particles such as size, hardness, shape and their electrical and thermal conductivities. A detailed analysis of the physics of the contact spots and the temperature development during current flow at the contact is given. It is shown that the polymer matrix has a strong influence on the electrical conductivity due to its elastic properties and the response to external thermal and mechanical stimulation. Strong changes in the electrical conductivity of conducting polymer composites can be realized either by thermal stimuli, leading to a positive and negative temperature coefficient in resistivity, or by applying mechanical stress. By using nonlinear fillers an additional degree of functionality can be achieved with conducting polymers. 相似文献
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聚合物纳米复合材料因其优良的电气绝缘性能在电介质绝缘领域得到了广泛应用。为了获得性能优良的环氧树脂绝缘材料,将采用硅烷偶联剂进行表面处理后的纳米Al N颗粒加入环氧树脂绝缘材料中,采用溶液共混法制备了Al N质量分数分别为0%、0.5%、1%、3%、5%、7%的Al N/环氧树脂复合材料,研究了不同Al N质量分数对Al N/环氧树脂复合材料绝缘性能的影响。结果表明,树脂基体和Al N填料之间实现了有效的结合,提高了环氧树脂的热稳定性;Al N的加入一定程度上减小了复合材料的体积电阻率,并且增大了复合材料的介质损耗因数,但对复合材料电气绝缘性能的影响较小;当纳米Al N颗粒质量分数为3%时,Al N/环氧树脂复合材料的交流击穿电场强度最大。因此,添加适量纳米Al N颗粒能够提高干式变压器环氧树脂的电气绝缘性能。 相似文献
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F. Greuter M. Siegrist P. Kluge-Weiss R. Kessler L. Donzel R. Loitzl H. J. Gramespacher 《Journal of Electroceramics》2004,13(1-3):739-744
Microvaristors are tiny electroceramic particles, which have highly nonlinear, voltage controlled electrical transport properties and can be used as active fillers in a variety of insulating matrix materials for functional composites. Due to the internal grain boundary structure, each individual microvaristor particle shows an IV-characteristics similar to the one known from bulk ceramics, except for the scaled down switching voltage. By controlling the material formulation, the particle morphology and the sintering conditions the switching characteristics of microvaristors can be tailored for specific applications.In the present paper the basic properties of ZnO microvaristors are described and it is shown how they impart their nonlinearity to the composite. A single microvaristor can withstand surprisingly high current loadings, without major changes in their electrical properties. Combined with the high manufacturing flexibility known from polymer processing, the varistor composites can be used for new solutions in overvoltage protection or control of electrical fields. 相似文献
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Bismuth titanate (BiT) based composites containing silver particles are fabricated by a solution chemical process. Incorporation
of silver particles does not result in unwanted reaction phase. SEM micrographs reveal fine silver particles distribute at
BiT grain boundaries and into larger BiT plate-like grains. With the addition of silver, the dielectric constant increases
up to ∼10 times higher than that of pure BiT ceramic, which can be attributed to the effective electric fields developed around
the dispersed metal particles and the percolation effect. Additionally, the dielectric losses are significantly reduced by
incorporating silver particles, and the values of BiT/Ag composites are lower than 0.5%. The dielectric properties of BiT/Ag
composites are nearly frequency independent in the measured frequency range (1 kHz to 1 MHz). 相似文献
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碳纳米管填充的高介电常数聚合物基复合电介质材料 总被引:5,自引:0,他引:5
介绍了碳纳米管电性能及其功能化改性、以及利用碳纳米管掺杂聚合物制备柔性高介电常数复合材料的研究现状,发现化学气相沉积法得到的多壁碳纳米管(MWNT)在化学处理前后形成的聚合物基复合材料具有明显不同的分散特性和介电性能.相对于微米级球形导电颗粒填充的复合材料,一维尺度碳纳米管填充的复合材料具有明显低得多的渗流阈值,低渗流阈值可以明显保持聚合物基体优良的机械性能.期望在这一领域从工程电介质的角度做深入的研究工作,以发现碳纳米管在聚合物基复合材料领域所表现出的新特性、新现象. 相似文献
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Fabrication and evaluation of PZT/Ag composites and functionally graded piezoelectric actuators 总被引:1,自引:0,他引:1
Metallic Ag as the second phase was added into PZT ceramic matrix to fabricate piezoelectric composites and functionally graded
actuators by gradually altering Ag concentration, aimed to improve mechanical properties and to solve possible interfacial
debonding usually observed in conventional bimorph-type piezoelectric actuator. The PZT/Ag composites were obtained by directly
co-firing PZT and Ag powders at 1200∘C for 1 h. The fracture strength σ
f
and fracture toughness K
IC
, as well as the corresponding piezoelectric properties, were firstly evaluated upon the PZT/Ag composites for Ag concentrations
of 0–30 vol%. The mechanical properties for the PZT/Ag composites were found to be greatly enhanced compared with pure PZT
ceramics: from 69 to 129 MPa for σ
f
and from 1.0 to 3.7 MPa.m1/2 for K
IC
. With increasing Ag concentration, the piezoelectric constant d
33 of PZT/Ag composites was found to decrease from 419 to 86 pC/N. Then, a functionally graded actuator was fabricated and evaluated
in terms of electric-induced curvature k. The PZT/Ag FGM actuator with size of 12 mm × 3 mm × 1 mm has a curvature k of 0.03–0.17 m−1 that corresponds to applied voltages of 100–500 V. A comprehensive comparison was made on the mechanical property enhancements
by the metal particles dispersion, and the bending displacements produced by the FGM actuators between the PZT/Ag and previously
fabricated PZT/Pt systems. 相似文献
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Bo Liu Boggs S.A. Shaw M.T. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2001,8(2):173-181
We report the results of numerical simulations for the change of both mechanical and electrical properties of elastomers with anisotropically filled polarizable particles under capacitively graded electric and mechanical fields. Such composites have potential applications in electromechanical control. We have used numerical techniques to study the effect of particle shape, permittivity/conductivity ratio, and spatial arrangement on the shear modulus as a function of the electric field. We also investigated the influence of the high field and nonlinear conductivity in the polymer matrix. The results indicate that electrostatic energy and changes therein, which result in electro-rheological effects, are concentrated between particles, and that the electrostatic interaction between the particles is concentrated in a very narrow regime at the tip of the particles, The interaction increases with the electric field intensity until the field between the particles is high enough to cause nonlinear electrical conduction in the polymer, resulting in a redistribution of the electric field and electrostatic energy 相似文献