共查询到20条相似文献，搜索用时 701 毫秒
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Cu-Ag filamentary microcomposites with different Ag contents were prepared by cold drawing and intermediate heat treatments. The microstructure characterization and filamentary distribution were observed for two-phase alloys under different conditions. The effect of heavy drawing strain on the microstructure evolution of Cu-Ag alloys was investigated. The results show that the microstructure components consist of Cu dendrites, eutectic colonies and secondary Ag precipitates in the alloys containing 6%-24% （mass fraction） Ag. With the increase in Ag content, the eutectic colonies in the microstructure increase and gradually change into a continuous net-like distribution. The Cu dendrites, eutectic colonies and secondary Ag precipitates are elongated in an axial direction and developed into the composite filamentary structure during cold drawing deformation. The eutectic colonies tend to evolve into filamentary bundles. The filamentary diameters decrease with the increase in drawing strain degree for the two-phase alloys, in particular for the alloys with low Ag content. The reduction in filamentary diameters becomes slow once the drawing strain has exceeded a certain level. 相似文献
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Micro-pin-fin cooler mounted on the power chip enables the heat removal to meet modern microsystem requirement. Carbon nanotubes
(CNTs) have been proven as a potential material for micro-coolers due to the superior thermal conductivity, good mechanical
property and so forth, and there appear various applications of CNTs in the micro-cooler technology. In the present paper,
an analysis of the thermal and hydraulic characteristics of the micro-pin-fin heat sink was conducted, where air was used
as the cooling medium and an impinging jet was introduced to enhance the heat transfer. Three-dimension computational fluid
dynamics (CFD) simulations were carried out for micro-pin-fin coolers with various parameters, including the pin-fin size
and pattern as well as the jet velocity and nozzle diameter. The flow field and thermal properties of the micro-pin-fin heat
sink were obtained, and the heat removal efficiency was evaluated. 相似文献
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采用真空热蒸镀法,以热活化延迟荧光(TADF)材料为主体材料、发光材料为客体材料制备混合薄膜发光层,以提高蓝色荧光材料的OLED发光效率。当OLED器件结构为ITO/HAT-CN(5 nm)/TAPC(30 nm)/TCTA(10 nm)/Blue-Or:DMAC-DPS(30%,30 nm)/DPEPO(10 nm)/Bphen(30 nm)/LiF(1 nm)/Al(70 nm)时,器件的光电性能最佳。此蓝光TADF-OLED器件的外量子效率为12.39%,电流效率为21.68 cd/A,功率效率为19.44 lm/W。研究发现改变TADF-OLED的掺杂主体材料和添加空穴注入层均可有效地提高器件的光电特性。实验内容与该领域的前沿科学研究相结合,OLED器件的光电性能稳定、实验现象显著,适于引入本科实验课程。通过该综合实验学生可以夯实实验基础、了解研究热点、掌握最新的科研动态。 相似文献
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Xiao-ting Shen Yan-zhen Zhang Fang Xiao Jing Zhu Xiao-dong Zheng 《Journal of Zhejiang University. Science. B》2017,18(7):615-625
The aim of this study was to research the changes in cytotoxicity and antibacterial properties after silver nanoparticles (AgNPs) were incorporated into the surface coating of dental alloys. AgNPs were attached to cobalt chromium alloys and pure titanium using a hydrothermal method, according to the reaction: AgNO3+NaBH4→ Ag+1/2H2+1/2B2H6+NaNO3. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of the alloys when in contact with osteogenic precursor cells (MC3T3-E1) from mice and mesenchymal stem cells (BMSC) from rats. The antibacterial properties of dental alloys incorporating three different concentrations (10, 4, and 2 μmol/L) of AgNPs were tested on Staphylococcus aureus (SA) and Streptococcus mutans (MS). High cytotoxicity values were observed for all dental alloys that contained 0% of AgNPs (the control groups). The incorporation of AgNPs reduced cytotoxicity values. No significant difference was observed for antibacterial performance when comparing dental alloys containing AgNPs to the respective control groups. The results demonstrated that the cobalt chromium alloys and pure titanium all had cytotoxicity to MC3T3-E1 and BMSC and that the incorporation of AgNPs could reduce this cytotoxicity. The concentrations of AgNPs adopted in this study were found to have no antibacterial action against SA or MS. 相似文献
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The various stages and progress in the development of interconnect materials for solid oxide fuel cells (SOFCs) over the last two decades are reviewed. The criteria for the application of materials as interconnects are highlighted. Interconnects based on lanthanum chromite ceramics demonstrate many inherent drawbacks and therefore are only useful for SOFCs operating around 1000 ℃. The advance in the research of anode-supported flat SOFCs facilitates the replacement of ceramic interconnects with metallic ones due to their significantly lowered working temperature. Besides, interconnects made of metals or alloys offer many advantages as compared to their ceramic counterpart. The oxidation response and thermal expansion behaviors of various prospective metallic interconnects are examined and evaluated. The minimization of contact resistance to achieve desired and reliable stack performance during their projected lifetime still remains a highly challenging issue with metallic interconnects. Inexpensive coating materials and techniques may play a key role in pro moting the commercialization of SOFC stack whose interconnects are constructed of some current commercially available alloys. Alternatively, development of new metallic materials that are capable of forming stable oxide scales with sluggish growth rate and sufficient electrical conductivity is called for. 相似文献
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首先采用水热法制备出铁镍合金,然后将铁镍合金加入到含有超分子氢键网络的聚酰胺高分子基体中,得到一种具有导电性能的自修复高分子材料。通过扫描电子显微镜、X-射线衍射仪、电阻率测定仪等手段对样品的结构、形貌、导电及自修复性能进行了研究。结果表明,原料中Fe2＋与Ni2＋的摩尔比对铁镍合金形貌影响较大。当Fe2＋与Ni2＋摩尔比为70∶25时,产物形貌较规整。添加铁镍合金后,高分子材料的电导率呈上升趋势。当铁镍合金质量分数为45%时,自修复导电高分子材料的修复率达80%。 相似文献
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P(EA-MAn-APTES)/二氧化硅有机无机杂化材料的合成和表征 总被引：1，自引：0，他引：1
采用γ氨丙基三乙氧基硅烷 (APTES)作为偶联剂,以丙烯酸乙酯(EA)、顺丁烯二酸酐(MAn)和正硅酸乙酯(TEOS)为原料,通过自由基溶液聚合和溶胶凝胶过程制得了P(EA-MAn-APTES)/二氧化硅有机无机杂化材料,其中TEOS的质量分数从0变化至25%.利用傅立叶红外(FT-IR)光谱、溶胶抽取、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、示差扫描量热法(DSC)和热重分析(TGA)性能测试装置对材料的结构、凝胶含量、表面形貌、粒子大小和热性能进行了表征.结果表明:有机相与无机相之间是以共价键结合的,杂化材料中凝胶的含量较高,聚合物基体中SiO2是纳米复合的,具有较好的分散性和热稳定性. 相似文献
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采用浸渍法在二氧化硅多孔材料中负载壳聚糖制备壳聚糖/SiO2复合材料,通过X射线衍射、扫描电子显微镜、傅立叶变换红外光谱等方法对所制备材料的组成与结构进行了表征,采用热重-差示扫描量热法研究了复合材料的热稳定性,采用电流中断法测定所制备材料的电导率来衡量其质子传导性能,并考察了壳聚糖溶液浓度对壳聚糖/SiO2复合材料导电性能的影响。结果表明,壳聚糖/SiO2复合材料具有较高的热稳定性,复合材料的电导率随着壳聚糖乙酸溶液浓度的增加而增加,当壳聚糖乙酸溶液质量百分比浓度为2.5%时,电导率可达1.82 S/cm。 相似文献
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Aluminum nitride （AlN）/borosilicate glass composites were prepared by the tape casting process and hot-press sintered at 950 ℃ with AIN and SiO2-B203-ZnO-Al2O3-Li2O glass as starting materials. We characterized and analyzed the variation of the microstructure, bulk density, porosity, dielectric constant, thermal conductivity and thermal expansion coefficient （TEC） of the ceramic samples as a function of AIN content. Results show that AIN and SiO2-B2O3-ZnO-Al2O3-Li2O glass can be sintered at 950 ℃, and ZnAI204 and Zn2SiO4 phase precipitated to form glass-ceramic. The performance of the ceramic samples was determined by the composition and bulk density of the composites. Lower AlN content was found redounding to liquid phase sintering, and higher bulk density of composites can be accordingly obtained. With the increase of porosity, corresponding decreases were located in the dielectric constant, thermal conductivity and TEC of the ceramic samples. When the mass fraction of AlN was 40%, the ceramic samples possessed a low dielectric constant （4.5-5.0）, high thermal conductivity （11.6 W/（m.K）） and a proper TEC （3.0× 10^-6 K^-1 which matched that of silicon）. The excellent performance makes this kind of low temperature co-fired ceramic a promising candidate for application in the micro-electronics packaging industry. 相似文献
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ＥｐｉｔａｘｉａｌＧｒｏｗｔｈｏｆＹＳＺａｓＢｕｆｅｒＬａｙｅｒｓｆｏｒＨｉｇｈＴｃＳｕｐｅｒｃｏｎｄｕｃｔｉｎｇＦｉｌｍｓｏｎＳｉＳｕｂｓｔｒａｔｅｓＱｉａｎＷｅｎｓｈｅｎｇ（钱文生）ＬｉｕＲｏｎｇ（刘融）ＷｅｉＴｏｎｇｌｉ（魏同立）（Ｍｉｌｒｏｅ... 相似文献
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Thermal-mechanical behavior of functionally graded thick plates, with one pair of opposite edges simply supported, is investigated based on 3D thermoelasticity. As for the arbitrary boundary conditions, a semi-analytical solution is presented via a hybrid approach combining the state space method and the technique of differential quadrature. The temperature field in the plate is determined according to the steady-state 3D thermal conduction. The Mori-Tanaka method with a power-law volume fraction profile is used to predict the effective material properties including the bulk and shear moduli, while the effective coefficient of thermal expansion and the thermal conductivity are estimated using other micromechanics-based models. To facilitate the implementation of state space analysis through the thickness direction, the approximate laminate model is employed to reduce the inhomogeneous plate into a homogeneous laminate that delivers a state equation with constant coefficients. The present solutions are validated by comparisons with the exact ones for both thin and thick plates. Effects of gradient indices, volume fraction of ceramics, and boundary conditions on the thermomechanical behavior of functionally graded plates are discussed. 相似文献
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在纯铜熔体中以 Al-RE 中间合金形式加入富 Ce 混合稀土,探讨了 RE 加入量对电工用铜母线铸态组织、力学性能和导电性的影响规律.结果表明:纯铜基体的纯净度随RE加入量的增加而明显提高,当w(RE)=0.02%时,结晶组织最为细小,力学性能得到改善;添加RE可显著改善纯铜的导电性,其影响作用取决于稀土化合物的分布状态及基体的纯净度,当w(RE)》0.02%后,导电率略为降低.当w(RE)=0.05%,可使纯铜获得较理想的综合性能,基本满足高强高韧高导铜母线的生产要求. 相似文献
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INTRODUCTION Monocrystalline SBN (Strontium barium nio-bium, SrxBa1?xNb2O6, denoted SBNx?100, where 0.25≤x≤0.75) solid solution, is currently being inves-tigated as potential material for many micro-device applications, such as piezoelectric infrared detectors, piezoelectric, electro-optic modulators, and holo-graphic storage (Koch et al., 1998), because SBN has one of the largest known linear electro-optic coeffi-cients (r33=1300 pm/V for SBN75), two orders of magnitude larger th… 相似文献
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Mechanical and physical properties, such as tensile strength, elongation at break, modulus of elasticity, Shore D hardness,
melt flow rate (MFR), and electrical and thermal conductivities of composites with high density polyethylene matrix reinforced
with Al powders were investigated experimentally. Measurements of the mechanical and physical properties were performed up
to a reinforcing component concentration of 30% volume Al powder and compared with mathematical models from the literature.
The obtained results have shown that experimental data were in good agreement with theoretical data. The ultimate tensile
strength (UTS) and elongation at break decreased with increasing Al powder content, which was attributed to the introduction
of discontinuities in the polymer structure, and modulus of elasticity increased with increasing Al content. The composite
preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume for
system high density polyethylene-Al (HDPE-Al). There was a cluster formation of Al particles at higher Al contents in the
polymer matrix. Electrical and thermal conductivity values of HDPE-Al composites were higher than pure HDPE values. 相似文献
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以吐温80为分散剂,分别以丙烯酰胺和N,N’-亚甲基双丙烯酰胺为单体和交联剂,制备中间相碳微球/石墨（MCMB/G）浆料,采用凝胶注模工艺,制得直接醇类燃料电池管状阴极支撑体素坯,经液态干燥、滚动干燥和埋石墨粉烧结等过程处理制得其样品。所制备的直接醇类燃料电池管状阴极支撑体物理性能为：孔隙率42.7%,电阻率0.0276Ω·cm,抗折强度6.23 MPa,抗压强度16.29 MPa,具有收缩率低、变形量小、石墨化度高、电导率高、力学性能好等特点。 相似文献