共查询到20条相似文献,搜索用时 18 毫秒
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1-3-2型压电陶瓷/聚合物复合材料的理论模型 总被引:2,自引:0,他引:2
根据Chan的1-3型复合材料理论模型和Newnham的复合材料串并联理论,提出了一种用于计算新型1-3-2型压电陶瓷/聚合物复合材料的介电常数和压电常数的理论模型.并制备了一批1-3-2型压电复合材料样品,把理论模型的计算值与实际测量的材料参数进行了比较,结果表明两者符合较好,误差小于10%. 相似文献
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Ken’ichiro Kita Masaki Narisawa Atsushi Nakahira Hiroshi Mabuchi Masaki Sugimoto Masahito Yoshikawa 《Journal of Materials Science》2010,45(13):3397-3404
We synthesized ceramic fibers based on silicon carbide (SiC) from polymer blends of polycarbosilane (PCS) and polymethylphenylsiloxane
(PMPhS) by melt-spinning and radiation curing. PMPhS was compatible with PCS up to 30 mass%, and formed a transparent melt
at temperatures higher than 513 K. The softening point was also lowered by adding PMPhS and 15 mass% of PMPhS to PCS was the
most suitable condition for obtaining thin fibers with an average diameter of 14.4 μm. Due to the lowered softening point
of the PCS–PMPhS fibers, γ-ray curing in air was adopted. The ceramic yield of the cured fiber was 85.5% after pyrolysis at
1273 K. In spite of the small diameter, the resulting tensile strength at 1273 K was rather limited at 0.78 GPa. Blooming
of the PMPhS component during pyrolysis may have caused surface defects. After high-temperature pyrolysis at 1673–1773 K,
a porous nanocrystalline SiC fiber with a unique microstructure was obtained with surface area of 70–150 m2/g. When the fiber was pyrolyzed at the same temperature under a highly reductive atmosphere, wire bundle-shaped fibers were
obtained by gas evolution and reactions. 相似文献
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《Composites Science and Technology》1988,33(2):121-133
PVC-silica and PVC-alumina powder ranging in filler-to-matrix ratios from 0·33 to 3 were implosively compacted. Impact pressures of between 15 and 25 GPa produced compacts of average relative densities approaching 90% with high compressive fracture strength. The effects of the initial (tap) density, filler-to-matrix ratio and impact pressures on the mechanical properties of these composites are discussed. 相似文献
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Kim ES Jeon CJ 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(9):1939-1946
Effects of ZnNb(2)O(6) content and crystallinity of polymers on the dielectric properties of ZnNb(2)O(6)/polytetrafluoroethylene (PTFE), polypropylene (PP), and polystyrene (PS) composites were investigated at microwave frequencies. With increasing ZnNb(2)O(6) content, the dielectric constant (K) of the composites increased, whereas the dielectric loss (tanδ) and temperature coefficient of resonant frequency (TCF) decreased. The tanδ of the composites with amorphous PS was lower than those of the composites with semi-crystalline PP and PTFE. For the composites with semi-crystalline PTFE and PP, the tanδ was strongly dependent on the degree of crystallinity of composites. Several types of theoretical models were applied to predict the effective dielectric properties of the composites. Typically, K of 5.73, tan δ of 1.45 x 10(-3), and TCF of 2.66 ppm/°C were obtained for the PP composites with 0.5 volume fraction V(f) of ZnNb(2)O(6). 相似文献
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M. S. PANAJKAR G. M. PHATAK K. GANGADHARAN I. K. GOPALKRISHNAN C. GOPINATHAN 《Journal of Materials Science Letters》1997,16(3):218-220
Abstracts are not published in this journal
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
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Noa Lachman Erica Wiesel Roberto Guzman de Villoria Brian L. Wardle H. Daniel Wagner 《Composites Science and Technology》2012
Growing carbon nanotubes (CNTs) on the surface of fibers has the potential to modify fiber–matrix interfacial adhesion, enhance the composite delamination resistance, and possibly improve its toughness and any matrix-dominated elastic property as well. In the present work aligned CNTs were grown upon ceramic fibers (silica and alumina) by chemical vapor deposition (CVD) at temperatures of 650 °C and 750 °C. Continuously-monitored single fiber composite (SFC) fragmentation tests were performed on pristine as well as on CNT-grown fibers embedded in epoxy. The critical fragment length, fiber tensile strength at critical length, and interfacial shear strength were evaluated. Significant increases (up to 50%) are observed in the fiber tensile strength and in the interfacial adhesion (which was sometimes doubled) with all fiber types upon which CNTs are CVD-grown at 750 °C. We discuss the likely sources of these improvements as well as their implications. 相似文献
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Shape memory polymers (SMPs) are a kind of very important smart polymers. In order to improve the properties or obtain new functions of SMPs, SMP composites and blends are prepared. We thoroughly examine the research in SMP composites and blends achieved by numerous research groups around the world. The preparation of SMPs composites and blends is mainly for five aims: (1) to improve shape recovery stress and mechanical properties; (2) to decrease shape recovery induction time by increasing thermal conductivity; (3) to create new polymer/polymer blends with shape-memory effect (SME); (4) to tune switch temperature, mechanical properties, and biomedical properties of SMPs; (5) to fabricate shape memory materials sensitive to electricity, magnetic, light and moisture. The trend of SMP composite development is discussed. SMP composites and blends exhibit novel properties that are different from the conventional SMPs and thus can be utilized in various applications. 相似文献
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Jafarzadeh S Thormann E Rönnevall T Adhikari A Sundell PE Pan J Claesson PM 《ACS applied materials & interfaces》2011,3(5):1681-1691
The high interest in applications of conducting polymers, especially polyaniline (PANI), makes it important to overcome limitations for effective usage due to poor processability and solubility. One promising approach is to make blends of PANI in polymeric resins. However, in this approach other problems related to the difficulty of achieving a homogeneous PANI dispersion arise. The present article is focused on this general problem, and we discuss how the synthesis method, choice of dopant and solvent as well as interfacial energies influence the dispersibility. For this purpose, different synthesis methods and dopants have been employed to prepare nanostructures of polyaniline. Dynamic light scattering analysis of dispersions of the synthesized particles in several solvents was employed in order to understand how the choice of solvent affects PANI aggregation. Further information on this subject was achieved by scanning electron microscopy studies of PANI powders dried from various solutions. On the basis of these results, acetone was found to be a suitable dispersion medium for PANI. The polymer matrix used to make the blends in this work is a UV-curing solvent-free resin. Therefore, there is no low molecular weight liquid in the system to facilitate the mixing process and promote formation of homogeneous dispersions. Thus, a good compatibility of the components becomes crucial. For this reason, surface tension and contact angle measurements were utilized for characterizing the surface energy of the PANI particles and the polyester acrylate (PEA) resin, and also for calculating the interfacial energy between these two components that revealed good compatibility within the PANI/PEA blend. A novel technique, based on centrifugal sedimentation analysis, was employed in order to determine the PANI particle size in PEA resin, and high dispersion stability of the PANI/PEA blends was suggested by evaluation of the sedimentation data. 相似文献
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Chan HW Unsworth J 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1989,36(4):434-441
A theoretical model is presented for combining parameters of 1-3 ultrasonic composite materials in order to predict ultrasonic characteristics such as velocity, acoustic impedance, electromechanical coupling factor, and piezoelectric coefficients. Hence, the model allows the estimation of resonance frequencies of 1-3 composite transducers. This model has been extended to cover more material parameters, and they are compared to experimental results up to PZT volume fraction ν of 0.8. The model covers calculation of piezoelectric charge constants d 33 and d 31. Values are found to be in good agreement with experimental results obtained for PZT 7A/Araldite D 1-3 composites. The acoustic velocity, acoustic impedance, and electromechanical coupling factor are predicted and found to be close to the values determined experimentally 相似文献
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A unidirectional composite and a series of bidirectionally reinforced composites were fabricated using carbon fibre reinforcement in a silicon carbide matrix, which was produced by the pyrolysis of a polymer precursor. The thermal expansion over the temperature range 20–1000 °C has been measured and the thermal diffusivity measured over the temperature range 200–1200 °C. Thermal diffusivity data was converted to conductivity data using measured density and literature specific heat data. Metallographic examination has been carried out on the composites and the results are discussed in terms of the observed microstructural features. 相似文献
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在高温转变陶瓷工艺过程中,通过不同金属元素(Ni、Mn、Co和Fe)的添加,原位反应合成出Si-CN陶瓷基体的复合材料.由于金属元素的存在,使得所合成的复合材料的质量损失减小,密度增加.富金属相能均匀分布在基体材料中,复合材料无明显缺陷.XRD分析结果表明,Ni、Mn和Fe在高温分解过程中与基体都发生反应,分别生成了Ni31 Si12、Mn5Si3和Mn2N0.86、Fe3Si,而Co没有.由于这些不同富金属相的存在,使得复合材料的磁学性能在低温(77K)和室温(300K)有所不同. 相似文献
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Contact-damage-resistant ceramic/single-wall carbon nanotubes and ceramic/graphite composites 总被引:5,自引:0,他引:5
There has been growing interest in incorporating single-wall carbon nanotubes (SWNTs) as toughening agents in brittle ceramics. Here we have prepared dense Al(2)O(3)/SWNT composites using the spark-plasma sintering (SPS) method. Vickers (sharp) and Hertzian (blunt) indentation tests reveal that these composites are highly contact-damage resistant, as shown by the lack of crack formation. However, direct toughness measurements, using the single-edge V-notch beam method, show that these composites are as brittle as dense Al(2)O(3) (having a toughness of 3.22 MPa m(0.5)). This type of unusual mechanical behaviour was also observed in SPS-processed, dense Al(2)O(3)/graphite composites. We argue that the highly shear-deformable SWNTs or graphite heterogeneities in the composites help redistribute the stress field under indentation, imparting the composites with contact-damage resistance. These composites may find use in engineering and biomedical applications where contact loading is important. 相似文献
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《Materials Letters》2006,60(13-14):1687-1692
Ceramic foam–polymer composites have been made by infiltration without pressure. Cellular ceramics (SiC and SiO2·ZrO2) of various cell size, (10, 20 and 30 ppi), were selected and combined with an epoxy vinyl-ester resin to produce composite materials. The interconnected pores (open cells) in the ceramic allowed a polymer flow throughout. This allowed a “continuous” distribution of the polymer throughout the structure and hence a good transmission of stresses between phases which resulted in higher mechanical properties. The results of compressive and wear test up on the materials obtained show the influence of cell size and wetness on the interface formed between the constituents. The failure modes exhibited in these materials were also analysed. It was observed that the polymer suffered plastic deformation while the ceramic phase was largely subject to shearing forces resulting in isolated fracturing. 相似文献
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Thermal conductivity of ceramic particle filled polymer composites and theoretical predictions 总被引:1,自引:0,他引:1
Hong He Renli Fu Yanchun Han Yuan Shen Xiufeng Song 《Journal of Materials Science》2007,42(16):6749-6754
Models and theories for predicting the thermal conductivity of polymer composites were discussed. Effective Medium Theory
(EMT), Agari model and Nielsen model respectively are introduced and are applied as predictions for the thermal conductivity
of ceramic particle filled polymer composites. Thermal conductivity of experimentally prepared Si3N4/epoxy composite and some data cited from the literature are discussed using the above theories. Feasibility of the three
methods as a prediction in the whole volume fraction region of the filler from 0 to 1 was evaluated for a comparison. As a
conclusion: both EMT and Nielsen model can give a well prediction for the thermal conductivity at a low volume fraction of
the filler; Agari model give a better prediction in the whole range, but with larger error percentage. 相似文献
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S. Rajesh K. Sonoda A. Uusimaki K. H. Yang H. Y. Lu H. Jantunen 《Journal of Materials Science: Materials in Electronics》2013,24(1):191-195
High permittivity polymer composites were prepared using Bisphenol A epoxy resin and low loss alumina (Al2O3) coated silver (Ag) flakes for embedded passives. The uniformity and thickness of the Al2O3 layer were studied using both scanning and transmission electron microscopy (SEM and TEM). SEM was also used to investigate the morphology of the composites and the particle distribution. The dielectric properties of the composites were measured as a function of frequency and temperature. The composites showed a high relative permittivity of 370 with a low loss tangent of 0.07 at 1 MHz and a temperature coefficient of permittivity ~160 ppm/K. 相似文献