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Electronic Transport in Alloys with Phase Separation (Composites) 预览
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作者 Joachim Sonntag Bertrand Lenoir Pawel Ziolkowski 《复合材料期刊(英文)》 2019年第1期21-56,共36页
A measure for the efficiency of a thermoelectric material is the figure of merit defined by ZT = S2T/ρκ, where S, ρ and κ are the electronic transport coefficients, Seebeck coefficient, electrical resistivity and ... A measure for the efficiency of a thermoelectric material is the figure of merit defined by ZT = S2T/ρκ, where S, ρ and κ are the electronic transport coefficients, Seebeck coefficient, electrical resistivity and thermal conductiviy, respectively. T is the absolute temperature. Large values for ZT have been realized in nanostructured materials such as superlattices, quantum dots, nanocomposites, and nanowires. In order to achieve further progress, (1) a fundamental understanding of the carrier transport in nanocomposites is necessary, and (2) effective experimental methods for designing, producing and measuring new material compositions with nanocomposite-structures are to be applied. During the last decades, a series of formulas has been derived for calculation of the electronic transport coefficients in composites and disordered alloys. Along the way, some puzzling phenomenons have been solved as why there are simple metals with positive thermopower? and what is the reason for the phenomenon of the “Giant Hall effect”? and what is the reason for the fact that amorphous composites can exist at all? In the present review article, (1), formulas will be presented for calculation of σ = (1/ρ), κ, S, and R in composites. R, the Hall coefficient, provides additional informations about the type of the dominant electronic carriers and their densities. It will be shown that these formulas can also be applied successfully for calculation of S, ρ, κ and R in nanocomposites if certain conditions are taken into account. Regarding point (2) we shall show that the combinatorial development of materials can provide unfeasible results if applied noncritically. 展开更多
关键词 HALL EFFECT Giant HALL EFFECT SEEBECK Coefficient (Thermopower) Electron Density CONDUCTIVITY Thermal CONDUCTIVITY COMPOSITES Nanocomposites Percolation Theory
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Electrical, Thermal, and Mechanical Properties of Cu/Ti3AlC2 Functional Gradient Materials Prepared by Low-temperature Spark Plasma Sintering
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作者 陈艳林 PENG Hang +3 位作者 LOU Lang HUANG Kang YAN Ming 吴崇刚 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第4期876-882,共7页
Cu/Ti3AlC2 composite and functional-gradient materials with excellent electrical conductivity and thermal conductivity as well as good flexural properties were prepared by low-temperature spark plasma sintering of Cu ... Cu/Ti3AlC2 composite and functional-gradient materials with excellent electrical conductivity and thermal conductivity as well as good flexural properties were prepared by low-temperature spark plasma sintering of Cu and Ti3AlC2 powder mixtures. The phase compositions of the materials were analyzed by X-ray diffraction, and their microstructure was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Further, the electrical conductivity, thermal conductivity, and flexural properties of the materials were tested. Results show that, for the composite materials, the resistivity rises from 0.75 × 10^-7 Ω·m only to 1.32 × 10^-7 Ω·m and the thermal diffusivity reduces from 82.5 mm^2/s simply to 39.8 mm^2/s, while the flexural strength improves from 412.9 MPa to 471.3 MPa, as the content of Ti3AlC2 is increased from 5 wt%to 25 wt%. Additionally, the functional-gradient materials sintered without interface between the layers exhibit good designability, and their overall electrical conductivity, thermal conductivity, and flexural strength are all higher than those of the corresponding uniform composite material. 展开更多
关键词 Cu/Ti3AlC2 FUNCTIONAL gradient material ELECTRICAL CONDUCTIVITY THERMAL CONDUCTIVITY
Interplay between Carrier Polarization, Spin-Orbit Coupling and Exchange Field on Anomalous Hall Conductivity in the Presence of Magnetic Impurity in Mn Doped GaAs 预览
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作者 Lijalem Kelemu Shita 《凝固态物理国际期刊(英文)》 2019年第4期75-90,共16页
We develop a model Hamiltonian to treat anomalous Hall conductivity in dilute magnetic semiconductor (DMS) of type (III, Mn, V) considering the impurity potentials (potential due to interaction of spin of carriers wit... We develop a model Hamiltonian to treat anomalous Hall conductivity in dilute magnetic semiconductor (DMS) of type (III, Mn, V) considering the impurity potentials (potential due to interaction of spin of carriers with localized spin of dopant (Mn) and coulomb like potential). Using equation of motion in Green function together with Quantum Kubo-formula of conductivity, the anomalous Hall conductivity is calculated as function of spin-orbit coupling, exchange field and carrier polarization. The calculated result shows that at low impurity concentration, the interplay between spin polarization of carriers, spin-orbit coupling and exchange fields is crucial for existence of anomalous Hall conductivity. The monotonic increment of anomalous Hall conductivity with exchange field is observed for strong spin-orbit coupling limit. In weak spin-orbit coupling limit, the magnitude of anomalous Hall conductivity increases parabolically with the spin-orbit coupling. Our results provide an important basis for understanding the interplay between the spin polarization, spin-orbit coupling, and exchange field on anomalous Hall conductivity at low impurity concentration. The findings are also a key step to realize dissipationless quantum transport without external magnetic field. 展开更多
关键词 CONDUCTIVITY Magnetic IMPURITY Spin-Obit Coupling Exchange Field CARRIER POLARIZATION
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Quality of Potable Water Available to the Residents of Anambra State, Nigeria 预览
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作者 Chigozie John Onyinye Anarado Charity Ebere Anarado +4 位作者 Benjamin Chimezie Izuagbachukwu Uzorchukwu Michael Ogu Amarachi Maduka Chinyelu Ijeamaka Egwuatu Valentine Ifenna Onwukeme 《自然资源(英文)》 2019年第11期395-414,共20页
Public pipe-borne water system had collapsed in Anambra state of Nigeria, for over fifteen years, challenging the residents of the state to resort to alternative sources of potable water, notably, boreholes. It is imp... Public pipe-borne water system had collapsed in Anambra state of Nigeria, for over fifteen years, challenging the residents of the state to resort to alternative sources of potable water, notably, boreholes. It is imperative to continuously assess the quality of the water. In this work, two boreholes each in nineteen communities, one from Aguluzigbo, in three local government areas?(Anaocha, Awka-North, Awka-South) in the state were sampled, and tested for pH, Conductivity, Hardness, Total Suspended Solids, Lead, Arsenic, Cadmium, Bacteria and Yeast loads. The water samples were all soft and mostly acidic. While there were not much threats of yeast, the aerobic bacteria counts were above the acceptable limits. The Lead, Arsenic and Cadmium concentrations were above the tolerable limits in most communities in Anaocha and Awka-South. Arsenic, Lead, Cadmium were absent in all the samples in Awka-North except in four communities where Cadmium was present. Suspended solid contents were also high in all the Local Government Areas. Overall, the quality of the water consumed by the people in the selected population calls to question?of?the water and sanitation component of the public health system. 展开更多
关键词 Potable Water Cadmium Lead ARSENIC pH Bacteria Load Total Suspended SOLIDS CONDUCTIVITY HARDNESS
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SOFC阴极材料La0.7Sr0.3Fe0.7Co0.2Ni0.1O3-δ的制备与性能
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作者 李向国 李松波 +1 位作者 安胜利 张帆 《现代化工》 CAS CSCD 北大核心 2019年第10期92-96,共5页
采用溶胶-凝胶法、固相法制备La0. 7Sr0. 3Fe0. 7Co0. 2Ni0. 1O3-δ(LSFCN)中低温固体氧化物燃料电池阴极材料,通过热重-差热分析、X射线衍射、扫描电镜、直流四探针法、热膨胀系数、交流阻抗对材料的结构与性能进行研究。结果表明,2种... 采用溶胶-凝胶法、固相法制备La0. 7Sr0. 3Fe0. 7Co0. 2Ni0. 1O3-δ(LSFCN)中低温固体氧化物燃料电池阴极材料,通过热重-差热分析、X射线衍射、扫描电镜、直流四探针法、热膨胀系数、交流阻抗对材料的结构与性能进行研究。结果表明,2种方法制备的LSFCN均为单一的钙钛矿结构,并且与电解质SDC在950℃以下没发生化学反应,稳定性较好。溶胶-凝胶法制备的阴极粉体颗粒最小、形状规整、结晶度高。在测试温度400~800℃条件下,2种方法合成的阴极材料LSFCN是小极化子导电机制,电导率随着测试温度的升高而增大。溶胶-凝胶法制得的LSFCN的电导率均大于固相法,在800℃时最大达到619. 4S/cm。2种方法制备的LSFCN阴极样品与电解质SDC匹配性好。2种方法制备的LSFCN有利于氧在三相界面的传输,提高了材料的电化学性能。 展开更多
关键词 溶胶-凝胶法 固相法 钙钛矿 电导率 热膨胀 交流阻抗
氯化铬和氯化镍浓度及其存在形式对ChCl-EG低共熔溶剂电导率的影响 预览
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作者 朱啸林 徐存英 +5 位作者 唐杰 华一新 张启波 刘海 王祥 黄梦婷 《化工学报》 EI CAS CSCD 北大核心 2019年第7期2786-2794,共9页
研究了氯化铬(CrCl3·6H2O)和氯化镍(NiCl2·6H2O)浓度和存在形式对氯化胆碱-乙二醇(ChCl-EG)低共熔溶剂的黏度和电导率的影响。电喷雾质谱(ESI-MS)分析结果表明,在溶解有CrCl3·6H2O和NiCl2·6H2O的ChCl-EG(ChCl-EG-Ni... 研究了氯化铬(CrCl3·6H2O)和氯化镍(NiCl2·6H2O)浓度和存在形式对氯化胆碱-乙二醇(ChCl-EG)低共熔溶剂的黏度和电导率的影响。电喷雾质谱(ESI-MS)分析结果表明,在溶解有CrCl3·6H2O和NiCl2·6H2O的ChCl-EG(ChCl-EG-NiCl2·6H2O-CrCl3·6H2O)溶液中出现了配阴离子[Cr(H2O)2Cl4]和[Ni(H2O)2Cl4]^2-。由此可以推断,Cr^3+(或Ni^2+)的两个d轨道、4s和4p轨道发生d2sp3杂化,形成6个等同的杂化轨道,接受6个配体(Cl^-和H2O)形成阴离子配合物。该溶液的电导率随温度的升高而增大,随总金属离子浓度的增大而减小。此外,溶液黏度随温度和总金属离子浓度的变化趋势与电导率相反。这主要是由于镍和铬配离子的形成改变了溶液中的离子组成。 展开更多
关键词 低共熔溶剂 溶解 存在形式 电导率 黏度 配合物
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分散剂对磨制片状银粉性能的影响?
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作者 哈敏 董宁利 钟翔 《粉末冶金技术》 CAS CSCD 北大核心 2019年第1期36-39,45共5页
以热分解碳酸银得到的类球形银粉作为前驱体,使用硬脂酸、油酸、蓖麻油酸及正辛酸作为分散剂,采用机械球磨法制备片状银粉。通过扫描电镜(scanning electron microscope,SEM)、粒度分布统计(particle size distribution,PSD)、松装密度... 以热分解碳酸银得到的类球形银粉作为前驱体,使用硬脂酸、油酸、蓖麻油酸及正辛酸作为分散剂,采用机械球磨法制备片状银粉。通过扫描电镜(scanning electron microscope,SEM)、粒度分布统计(particle size distribution,PSD)、松装密度仪、振实密度仪、四探针仪等手段测试了片状银粉的显微形貌、粒度分布、松装密度、振实密度及导电性。结果表明,分散剂分子中碳链的长度影响片状银粉物理性能,使用油酸作为分散剂可以得到粒径分布窄、松装密度为1.0 g·cm-3、振实密度为1.7 g·cm-3的片状银粉,调制含质量分数50%Ag的低温固化银浆,其方阻小于10 mΩ·□-1。 展开更多
关键词 分散剂 片状银粉 机械球磨 导电性 物理性能
影响机油电导率相关因素分析 预览
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作者 黎长青 姚晓舸 +1 位作者 汪胜华 刘荣伟 《现代制造技术与装备》 2019年第6期156-158,共3页
机油电导率越低,机油绝缘性越好,越容易产生静电。影响机油电导率的因素有调配机油使用的基础油种类、添加剂种类、油中含有水分、杂质、机械杂质以及金属粉末等。
关键词 电导率 静电 酸碱离子
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高压大容量脉冲电容器保压过程中电压跌落的定量分析 预览
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作者 朱博峰 鲁军勇 +4 位作者 张晓 王鑫 戴宇峰 马涛 王杰 《国防科技大学学报》 EI CAS CSCD 北大核心 2019年第4期33-38,共6页
针对金属化膜脉冲电容器在实际使用中由于充电结束以后较长的保压时间而产生电压跌落和能量损失,并最终导致脉冲功率电源系统的实际有效储能和储能密度下降这一实际问题,基于一种高压大容量脉冲电容器电压跌落的实验数据,分别从电导特... 针对金属化膜脉冲电容器在实际使用中由于充电结束以后较长的保压时间而产生电压跌落和能量损失,并最终导致脉冲功率电源系统的实际有效储能和储能密度下降这一实际问题,基于一种高压大容量脉冲电容器电压跌落的实验数据,分别从电导特性、自愈特性、极化特性及其与能量损失的相关性出发,推导了介质薄膜电导率与电压跌落的定量关系并进行了电导率测量实验,推导了自愈能量与电压跌落的定量关系并进行了寿命实验,阐述了松弛极化与电压跌落的定量关系并进行了仿真。结果表明,介质泄漏、自愈以及松弛极化在电压跌落中所占比例分别为29.64%、11.75%及58.35%,导致所研究电容器电压跌落的主要因素是松弛极化。 展开更多
关键词 脉冲电容器 电压跌落 电导率 自愈 松弛极化
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RRA处理对7085铝合金微观组织演变及性能的影响
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作者 王艳娟 胡晓青 +1 位作者 曲庆文 吕正风 《金属热处理》 CAS CSCD 北大核心 2019年第8期45-49,共5页
通过对微观组织的TEM精细表征、断口的SEM观察、力学性能和导电率的测试等,研究了回归再时效处理(RRA)对7085铝合金微观组织演变及性能的影响。结果表明:回归温度越高,RRA处理后达到峰值硬度的时间越短,导电率增加速率越快;120℃×2... 通过对微观组织的TEM精细表征、断口的SEM观察、力学性能和导电率的测试等,研究了回归再时效处理(RRA)对7085铝合金微观组织演变及性能的影响。结果表明:回归温度越高,RRA处理后达到峰值硬度的时间越短,导电率增加速率越快;120℃×24 h预时效+200℃×8 min回归处理+120℃×24 h再时效为最佳的RRA工艺,抗拉强度、屈服强度和伸长率分别达到735 MPa、698 MPa和8. 5%,导电率达到44. 5%IACS;回归处理后的谷值硬度,与RRA处理后试样的峰值硬度达到时间一致;RRA处理后晶内主要为与基体呈共格关系的GP区和η’粒子,晶界附近存在宽度在70~80 nm的PFZ区。 展开更多
关键词 7085铝合金 回归再时效处理 微观组织 导电率 析出相
Study of structural, electrical, and photoluminescent properties of SrCeO3 and Sr2CeO4
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作者 Dharmendra Yadav Upendra Kumar Shail Upadhyay 《先进陶瓷(英文版)》 CSCD 2019年第3期377-388,共12页
Phase pure powders of SrCeO3 and Sr2Ce O4 have been synthesized by calcination at 1000℃for 14 h via solid state ceramic route.Ceramics/pellets of these samples have been obtained by sintering at 1200℃for 12 h.The Ri... Phase pure powders of SrCeO3 and Sr2Ce O4 have been synthesized by calcination at 1000℃for 14 h via solid state ceramic route.Ceramics/pellets of these samples have been obtained by sintering at 1200℃for 12 h.The Rietveld refinement of X-ray diffraction(XRD)pattern of sintered powders confirmed orthorhombic structure of both the samples with space group Pnma and Pbam for SrCeO3 and Sr2CeO4,respectively.Scanning electron microscopic(SEM)studies indicated that both the compounds have dense microstructure,but morphology and size of the grains are different.The impedance spectroscopy technique has been employed to study the relaxation phenomenon.DC conductivity of the samples has been measured in the temperature range of 200–600℃to understand the conduction mechanism.The activation energy for relaxation(Erelax)and DC conduction(Econd)are found to be the same for both the compounds.Based on the numerical value of activation energies,relaxation and conduction mechanism in both the samples are attributed to migration of doubly ionized oxygen vacancies(Vo··).Photoluminescence technique has been employed to confirm the existence of oxygen vacancies.These studies have indicated that migration of oxygen vacancies in Sr2CeO4 is occurring mainly along a and c direction,i.e.,via perovskite cells.Further,the present work has clearly indicated that besides optical properties,electrical properties of Sr2CeO4 are also interesting and can be utilized for various applications such as oxide ion conduction electrolyte in solid oxide fuel cells(SOFCs). 展开更多
关键词 SR2CEO4 SrCeO3 IMPEDANCE SPECTROSCOPY DC CONDUCTIVITY
Peristaltic Flow of Shear Thinning Fluid via Temperature-Dependent Viscosity and Thermal Conductivity
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作者 S.Noreen A.Malik M.M.Rashidi 《理论物理通讯:英文版》 SCIE CAS CSCD 2019年第4期367-376,共10页
In this paper Williamson ?uid is taken into account to study its peristaltic ?ow with heat effects. The study is carried out in a wave frame of reference for symmetric channel. Analysis of heat transfer is accomplishe... In this paper Williamson ?uid is taken into account to study its peristaltic ?ow with heat effects. The study is carried out in a wave frame of reference for symmetric channel. Analysis of heat transfer is accomplished by accounting the effects of non-constant thermal conductivity and viscosity and viscous dissipation. Modeling of fundamental equations is followed by the construction of closed form solutions for pressure gradient, stream function and temperature while assuming Reynold’s number to be very low and wavelength to be very long. Double perturbation technique is employed, considering Weissenberg number and variable ?uid property parameter to be very small. The effects of emerging parameters on pumping, trapping, axial pressure gradient, heat transfer coe?cient, pressure rise,velocity pro?le and temperature are analyzed through the graphical representation. A direct relation is observed between temperature and thermal conductivity whereas the indirect proportionality with viscosity. The heat transfer coe?cient is lower for a ?uid with variable thermal conductivity and variable viscosity as compared to the ?uid with constant thermal conductivity and constant viscosity. 展开更多
关键词 TEMPERATURE-DEPENDENT VISCOSITY TEMPERATURE-DEPENDENT thermal CONDUCTIVITY shear thinning?uid PERISTALSIS
杭州淤泥质土的电渗电导率特性研究
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作者 罗战友 陶燕丽 +2 位作者 周建 邹宝平 祝行 《岩石力学与工程学报》 EI CAS CSCD 北大核心 2019年第A01期3222-3228,共7页
采用改进的MillerSoilBox试验装置,基于杭州淤泥质土,在3种不同含水量和含盐量下开展电渗试验,从总电导率和区域电导率2个方面分析土体电导率变化规律和分布特征,以揭示杭州淤泥质土的电渗电导率特性。结果表明:不同初始含水量下,土体... 采用改进的MillerSoilBox试验装置,基于杭州淤泥质土,在3种不同含水量和含盐量下开展电渗试验,从总电导率和区域电导率2个方面分析土体电导率变化规律和分布特征,以揭示杭州淤泥质土的电渗电导率特性。结果表明:不同初始含水量下,土体总电导率相近,均随通电时间逐渐减小,同时土体总电导率与实时含水量呈近似线性变化,线性变化率随初始含水量的增加而降低;不同初始含盐量下,土体总电导率呈现先上升后下降并最终趋于平缓的变化,电渗前期,总电导率峰值随初始含盐量的增大而增大,峰值出现时间随初始含盐量提高而推迟,电渗后期,不同初始含盐量下土体总电导率趋于相近;随着电渗的开展,土体电导率分布不均匀性先逐渐增大后有所缓解,最终阴极附近区域土体电导率与其他区域差异较大;不同含水量或含盐量下,土体电导率分布在电渗前期差异较大,后期趋于相近。研究成果可进一步揭示电渗机制,为电渗法设计计算方法的提出提供理论依据。 展开更多
关键词 土力学 杭州淤泥质土 电渗 电导率 含水量 含盐量
基于非制冷微测辐射热计的非晶硅锗薄膜电学特性研究 预览
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作者 陈哲权 何勇 +2 位作者 方中 潘绪超 何源 《激光与红外》 CAS CSCD 北大核心 2019年第3期336-340,共5页
采用等离子体增强化学气相沉积方法(PECVD)制备了应用于微测辐射热计的非晶硅锗薄膜(a-SixGey),并研究了不同反应气体流量比GeH4/SiH4对薄膜电学性能参数(电阻温度系数TCR和电导率)的影响。研究结果表明,随着流量比GeH4/SiH4的增大,薄... 采用等离子体增强化学气相沉积方法(PECVD)制备了应用于微测辐射热计的非晶硅锗薄膜(a-SixGey),并研究了不同反应气体流量比GeH4/SiH4对薄膜电学性能参数(电阻温度系数TCR和电导率)的影响。研究结果表明,随着流量比GeH4/SiH4的增大,薄膜电阻温度系数降低,电导率则呈现上升趋势。所制备的薄膜表现出了高TCR值(约3.5%/K^-1),适中的电导率(1.47×10^-3(Ω·cm)^-1)和优良的薄膜电阻均匀性(非均匀性<5%),在微测辐射热计热敏材料领域具有良好的应用前景。 展开更多
关键词 非晶硅锗薄膜 PECVD 电阻温度系数 电导率 微测辐射热计
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Li、Mn掺杂对MgCoNiCuZnO5导电性能的影响 预览
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作者 陈见 尹周澜 张衡中 《有色金属工程》 CAS 北大核心 2019年第8期1-6,共6页
分别以Li2CO3和MnO为Li源和Mn源,采用高温固相烧结的方法,合成了Li、Mn掺杂的MgCoNiCuZnO5高熵金属氧化物(High-entropy oxides,HEOx)材料(Mg,Co,Ni,Cu,Zn)0.95Li0.05O0.975和(Mg,Co,Ni,Cu,Zn)0.95Mn0.05O。并与未掺杂的HEOx进行对比,... 分别以Li2CO3和MnO为Li源和Mn源,采用高温固相烧结的方法,合成了Li、Mn掺杂的MgCoNiCuZnO5高熵金属氧化物(High-entropy oxides,HEOx)材料(Mg,Co,Ni,Cu,Zn)0.95Li0.05O0.975和(Mg,Co,Ni,Cu,Zn)0.95Mn0.05O。并与未掺杂的HEOx进行对比,研究了Li和Mn两种不同金属元素对HEOx材料的相结构和导电性能的影响。交流阻抗的研究结果表明,Li、Mn掺杂后HEOx导电性明显提高,同时,紫外-可见-近红外吸收光谱表明三种材料都表现出半导体特性,其带隙宽度为1.2~1.7eV,并且Li、Mn掺杂后HEOx的直接带隙变小,Li-HEOx为1.23eV,Mn-HEOx为1.38eV。 展开更多
关键词 高熵金属氧化物 掺杂 导电性 带隙
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球状纳米二氧化钛/石墨烯复合材料的合成及导电性能 预览
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作者 刘琳 李莹 +4 位作者 鄂涛 杨姝宜 姜志刚 许丽岩 张天琪 《材料工程》 EI CAS CSCD 北大核心 2019年第8期97-102,共6页
采用改进的水热法制备二氧化钛/石墨烯(TiO2/G)复合导电材料,并研究水热温度以及石墨烯用量对TiO2/G复合材料导电性的影响。利用傅里叶变换红外(FTIR)光谱、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和电化学阻抗谱等测试手段对复... 采用改进的水热法制备二氧化钛/石墨烯(TiO2/G)复合导电材料,并研究水热温度以及石墨烯用量对TiO2/G复合材料导电性的影响。利用傅里叶变换红外(FTIR)光谱、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和电化学阻抗谱等测试手段对复合材料的结构,微观形貌以及导电性能进行表征,并确定最佳的水热温度以及石墨烯的最佳添加量。结果表明:石墨烯添加量为5%(质量分数),水热温度为160℃,TiO2/G复合材料的导电性最佳,其电阻率为13.46Ω·cm。复合材料中TiO2纳米颗粒为球状的锐钛矿相,直径为100~200nm左右,且均匀生长在石墨烯片层表面。其中,TiO2纳米颗粒生长于石墨烯片层上,有效地阻止石墨烯片层的聚集,有利于石墨烯片层间形成导电网络,提高电子迁移效率,赋予二氧化钛复合材料优异的导电性能。 展开更多
关键词 石墨烯 二氧化钛 导电性 水热法 复合导电材料
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Effects of silicon addition on optical properties of mould flux with iron oxide and estimation of apparent thermal conductivity of flux
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作者 Rie Endo Yo Kan +2 位作者 Takashi Watanabe Miyuki Hayashi Masahiro Susa 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第4期365-373,共9页
Mould flux with high absorptivity had been obtained in the reduction process of mould flux by silicon.For further utilisation of the mould flux with high absorptivity,the effect of silicon addition on the optical prop... Mould flux with high absorptivity had been obtained in the reduction process of mould flux by silicon.For further utilisation of the mould flux with high absorptivity,the effect of silicon addition on the optical property has been investigated.The synthesised mould flux powder with iron oxide was melted with the addition of silicon powder at 1703 K followed by quenching,thus forming a glassy sample.After 5-30-min reduction,the samples exhibited black opaque colour.Meanwhile,the samples that were reduced for 45-60 min had a bluish grey colour.Many iron-based particles dispersed in the samples were micrometre order in diameter.To determine the effect of iron particles on the optical properties of the sample,extinction,scattering and absorption efficiencies were calculated according to Mie theory.Result showed that both scattering on the iron particle and absorption by iron effectively increase the extinction efficiency in the mould flux.Moreover,the silicon particle in the flux has large scattering efficiency.The black opaque colour is contributed by the existence of silicon and iron particles.The apparent thermal conductivity was calculated for the solid flux.Results also indicated that the entire glassy mould flux would effectively work for mild cooling in a continuous casting process owing to high absorptivity and small thermal conductivity. 展开更多
关键词 MOULD FLUX Reduction Iron oxide Thermal CONDUCTIVITY OPTICAL property
Non-destructive microstructural analysis by electrical conductivity:Comparison with hardness measurements in different materials
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作者 Goncalo L.Sorger J.P.Oliveira +4 位作者 Patrick L.Inácio Norbert Enzinger Pedro Vilaca R.M.Miranda Telmo G.Santos 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第3期360-368,共9页
The use of non-destructive evaluation(NDE) techniques for assessing microstructural changes in processed materials is of particular importance as it can be used to assess, qualitatively, the integrity of any material/... The use of non-destructive evaluation(NDE) techniques for assessing microstructural changes in processed materials is of particular importance as it can be used to assess, qualitatively, the integrity of any material/structure. Among the several NDE techniques available, electrical conductivity measurements using eddy currents attract great attention owing to its simplicity and reliability. In this work, the electrical conductivity profiles of friction stir processed Ti6Al4 V, Cu, Pb, S355 steel and gas tungsten arc welded AISI 304 stainless steel were determined through eddy currents and four-point probe. In parallel, hardness measurements were also performed. The profiles matched well with the optical macrographs of the materials: while entering in the processed region a variation in both profiles was always observed. One particular advantage of electrical conductivity profiles over hardness was evident: it provides a better resolution of the microstructural alterations in the processed materials. Moreover, when thermomechanical processing induces microstructural changes that modify the magnetic properties of a material,eddy currents testing can be used to qualitatively determine the phase fraction in a given region of the material. A qualitative relation between electrical conductivity measurements and hardness is observed. 展开更多
关键词 NON-DESTRUCTIVE evaluation techniques Electrical CONDUCTIVITY HARDNESS FRICTION STIR processing Gas TUNGSTEN arc welding
离子色谱法测定左乙拉西坦中N-甲基苄胺
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作者 李吉庆 李仁勇 +1 位作者 赵全升 王玲 《分析试验室》 CAS CSCD 北大核心 2019年第7期863-866,共4页
建立了离子色谱测定左乙拉西坦中的N-甲基苄胺的方法。以阳离子交换柱为分析柱,3 mmol/L甲基磺酸溶液(含乙腈30%)为淋洗液,电导检测器检测。以非抑制电导检测,样品基质和常见阳离子对测定没有干扰。在0. 05~5μg/mL范围内线性关系良好(r... 建立了离子色谱测定左乙拉西坦中的N-甲基苄胺的方法。以阳离子交换柱为分析柱,3 mmol/L甲基磺酸溶液(含乙腈30%)为淋洗液,电导检测器检测。以非抑制电导检测,样品基质和常见阳离子对测定没有干扰。在0. 05~5μg/mL范围内线性关系良好(r=0. 999),定量限为50 ng/mL,添加左乙拉西坦的平均回收率为103. 6%。 展开更多
关键词 离子色谱 电导检测器 左乙拉西坦 N-甲基苄胺
铜基梯度镍电沉积层的制备及析氢性能研究 预览
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作者 柴多 贾予腾 +2 位作者 赵明 李建国 冯伟 《电镀与涂饰》 CAS CSCD 北大核心 2019年第13期641-646,共6页
采用双极性电沉积技术制备了铜基梯度镍电沉积层析氢电极材料,镀液组成和工艺条件为:NiSO4.6H2O200g/L,NiCl2.6H2O40g/L,H3BO340g/L,pH4,温度45℃,驱动电压5V或11V,时间5min。双极性电沉积过程中不同位置的铜/溶液界面过电位不同。所得... 采用双极性电沉积技术制备了铜基梯度镍电沉积层析氢电极材料,镀液组成和工艺条件为:NiSO4.6H2O200g/L,NiCl2.6H2O40g/L,H3BO340g/L,pH4,温度45℃,驱动电压5V或11V,时间5min。双极性电沉积过程中不同位置的铜/溶液界面过电位不同。所得镍电沉积层的结构和成分均呈梯度变化。电化学噪声测试结果表明,双极性电沉积过程由电化学极化控制,成核过程占主导,提高驱动电压有利于Ni的形核。在驱动电压11V下制备的梯度镍层在30%NaOH溶液中析氢的塔菲尔斜率为47mV/dec。铜基梯度镍有效结合了铜的优良导电性能和镍的析氢催化性能,与金属镍和常规电沉积制备的铜基镍电沉积层相比,具有更强的导电性,电解水制氢时的阴极电流损耗变小,从而令析氢效率提高。 展开更多
关键词 双极性电沉积 梯度结构 成核 析氢 导电性
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