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Modulating conductivity type of cuprous oxide（Cu2O） films on copper foil in aqueous solution by comproportionation

Journal of Materials Science & Technology 2019年第8期35卷 1570-1577页

作者： Changwei Tang Xiaohui Ning Jian Li Hui-Lin Guo Ying Yang Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of EducationCollege of Chemistry & Materials ScienceNorthwest UniversityXi'an 710127 China National Demonstration Center for Experimental Chemistry Education Northwest UniversityXi'an 710127 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049 China

Cuprous oxide(Cu2O)is an attractive material for photoelectrochemical(PEC)hydrogen production or photovoltaic application,because of its appropriate band gap,low material cost and non-toxic.In this paper,Cu2O films were obtained by comproportionation in acid cupric sulfate solutions with varying concentrations of potassium nitrate.Photoelectrochemical and electrochemical experiments,such as zero-bias photocurrent responses,voltammograms,and Mott-Schottky measurements,show that the Cu2O films grown in low(≤0.75 mol dm^–3)and high(≥1.00 mol dm^–3)nitrate ion concentrations presented n-type and p-type conductivity,respectively.Open circuit potential and polarization behavior were monitored to investigate the mechanism of modulating conductivity type.Nitrate ions consume protons in the plating solution during comproportionation with different concentrations of nitrate ions creating different pH at the Cu2O/solution interface.This gradient leads to the transformation of Cu2Ofilms conductivity changing from n-type to p-type with increasing the concentration of nitrate ions in the plating solution.This method could be used to fabricate homojunction electrode on metal substrate for PEC hydrogen production or photoelectric application.

关键词： Cuprous oxide(Cu2O) Comproportionation Semiconductor films Tuning conductivity Photoelectrochemical cell

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Thermal conductivity of natural rubber nanocomposites with hybrid fillers

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Chinese Journal of Chemical Engineering 2019年第4期27卷 928-934页

作者： Junping Song Xiteng Li Kaiyan Tian Lianxiang Ma Wei Li Shichune Yao Key Laboratory of Rubber-plastics Ministry of Education Shandong Provincial Key Laboratory of Rubber-plastics Chinese and German School of Science and Technology College of Electromechanical Engineering Qingdao University of Science and Technology Qingdao 266061 China Department of Energy Engineering Zhejiang University Hangzhou 310027 China Department of Mechanical Engineering Carnegie Mellon University Pittsburgh PA 15213-3890 USA

Natural rubber nanocomposites filled with hybrid fillers of multi-walled carbon nanotubes(CNTs) and carbon black(CB) were prepared. CNTs were ultrasonically modified in mixture of hydrogen peroxide(H2O2) and distilled water(H2O). The functional groups on the surface of CNTs, changes in nanotube structure and morphology were characterized by Fourier transform infrared spectroscopy(FT-IR), Raman Spectroscopy, and transmission electron microscopy(TEM). It shows that hydroxyl(OH·) is successfully introduced. The surface defects of modified CNTs were obviously higher than those of original CNTs, and the degree of agglomeration was greatly reduced. Thermal conductivity of the composites was tested by protection heat flow meter method. Compared with unmodified CNTs/CB filling system, the thermal conductivity of hybrid composites is improved by an average of 5.8% with 1.5 phr(phr is parts per hundred rubber) of hydroxyl CNTs and 40 phr of CB filled. A three-dimensional heat conduction network composed of hydroxyl CNTs and CB, as observed by TEM, contributes to the good properties. Thermal conductivity of the hybrid composites increases as temperature rises. The mechanical properties of hybrid composites are also good with hydroxyl CNTs filled nanocomposites;the tensile strength, 100% and 300% tensile stress are improved by 10.1%, 22.4% and 26.2% respectively.

关键词： Modified carbon nanotube Carbon black Hybrid filler Natural rubber Thermal conductivity

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Electrospun poly(ethylene oxide) nanofibrous composites with enhanced ionic conductivity as flexible solid polymer electrolytes

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High Voltage 2017年第1期2卷 25-31页

作者： Jun-Wei Zha Na Huang Kang-Qiang He Zhi-Min Dang Chang-Yong Shi Robert KwokYiu Li Department of Physics and Materials Science City University of Hong KongTat Chee AvenueKowloonHong KongPeople’s Republic of China Department of Polymer Science and Engineering School of Chemistry and Biological EngineeringUniversity of Science and Technology BeijingBeijing 100083People’s Republic of China State Key Laboratory of Electrical System Department of Electrical EngineeringTsinghua UniversityBeijing 100084People’s Republic of China Department of Elements Beijing Institute of Fashion TechnologyBeijing 100029People’s Republic of China

Solid polymer electrolytes(SPEs)have great potential to address the safety issues of lithium(Li)-ion batteries when compared with conventional liquid electrolytes,which makes them a promising alternative for next-generation high-energy batteries.In this work,poly(ethylene oxide)-lithium perchlorate(PEO–LiClO4)polymer electrolytes for Li-ion batteries were prepared using electrospinning.The crystallinity,ionic conductivity as well as mechanical properties were investigated.Ionic conductivities and mechanical properties of PEO–LiClO4 based SPE have been obviously increased by incorporating modified TiO2 nanofibres(TNFs)than TiO2 nanoparticles(TNPs),due to that both TNFs and TNPs can decrease the crystalline phase concentration of PEO and increase segmental flexibility of PEO.The SPE with 3 wt%TNFs exhibits the highest conductivity of 5.308×10−5 S cm−1 at 20°C and higher tensile strength of 13.8 MPa.These results highlight the potential of utilising the electrospinning method to improve the ionic conductivity of SPEs.

关键词： conductivity ionic polymer

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Effects of alloying elements on thermal conductivity of pearlitic gray cast iron

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Journal of Iron and Steel Research(International) 2019年第9期26卷 1022-1030页

作者： Gui-quan Wang Xiang Chen Yan-xiang Li Yuan Liu Hua-wei Zhang Zhong-li Liu School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China School of Nuclear Equipment and Nuclear Engineering Yantai UniversityYantai 264005ShandongChina Key Laboratory for Advanced Materials Processing Technology Tsinghua UniversityBeijing 100084China

A quantitative model is proposed to describe the thermal conductivity of alloyed pearlitic gray cast iron. The model is built by combining the computational thermodynamics and effective medium theory. The volume fractions and concentrations of precipitated phases in as-cast structure are estimated in consideration of partial and para-equilibrium. The conductivity of alloyed ferrite is calculated, taking into account the electronic and vibrational contributions of alloying elements. The model provides a good agreement with microstructure analysis and measured thermal conductivity. The influence of common alloying elements was discussed from the viewpoint of precipitation of phases and scattering of alloying atoms. This model can also be used as a numerical tool for designing the pearlitic gray cast irons with high thermal conductivity and high tensile strength.

关键词： Thermal conductivity Thermodynamic model Gray cast iron Alloying element

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Carreau fluid flow due to nonlinearly stretching sheet with thermal radiation, heat flux, and variable conductivity

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Applied Mathematics and Mechanics(English Edition) 2019年第11期40卷 1615-1624页

作者： A.M.MEGAHED Department of Mathematics Faculty of Science Benha University

A sophisticated theoretical and mathematical model is proposed.It is verified that this model can estimate and monitor the detailed behavior for the steady Carreau fluid flow past a nonlinear stretching surface and the predicted phenomena due to the presence of heat flux,thermal radiation,and viscous dissipation.Despite the fact that some properties of the fluid do not depend on the temperature,the fluid thermal conductivity is assumed to depend on the temperature.Based on accelerating the fluid elements,some of the kinetic energy for the fluid can be turned to the internal heating energy in the form of viscous dissipation phenomena.The contribution in this study is that a similar solution is obtained,in spite of the high nonlinearity of the Carreau model,especially,with the heat flux,variable conductivity,and viscous dissipation phenomena.Some of the major significant findings of this study can be observed from the reduction in the fluid velocity with enhancing the Weissenberg number.Likewise,the increase in the sheet temperature is noted with increasing the Eckert number while the reverse behavior is observed for increasing both the radiation parameter and the conductivity parameter.Finally,the accuracy and trust in the proposed numerical method are validated after benchmarking for our data onto the earlier results.

关键词： Carreau fluid nonlinearly stretching sheet variable heat flux variable conductivity

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Treatment of Wastewater with High conductivity by Pulsed Discharge Plasma

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Plasma Science and Technology 2014年第7期16卷 688-694页

作者：王兆均姜松刘克富 Institute for Electric Light Sources Fudan University

A wastewater treatment system was established by means of pulsed dielectric barrier discharge（DBD）. The main advantage of this system is that the wastewater is employed as one of the electrodes for the degradation of rhodamine B, which makes use of the high conductivity and lessenes its negative influence on the discharge process. At the same time, the reactive species like ozone and ultraviolet（UV） light generated by the DBD can be utilized for the treatment of wastewater. The effects of some factors like conductivity, peak pulse voltage, discharge frequency and pH values were investigated. The results show that the combination of these reactive species could enhance the degradation of the dye while the ozone played the most important role in the process. The degradation efficiency was enhanced with the increase of energy supplied. The reduction in the concentration of rhodamine B was much more effective with high solution conductivity;under the highest conductivity condition, the degradation rate could rise to 99%.

关键词： dielectric barrier discharge dye wastewater ozone degradation conductivity

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Boron nitride microsphere/epoxy composites with enhanced thermal conductivity

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High Voltage 2017年第3期2卷 147-153页

作者： Jiajia Sun De Wang Yimin Yao Xiaoliang Zeng Guiran Pan Yun Huang Jiantao Hu Rong Sun Jian-Bin Xu Ching-Ping Wong Shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhen 518055People's Republic of China Department of Nano Science and Technology Institute University of Science and Technology of ChinaSuzhou 215123People's Republic of China Department of Chemical Engineering Ordos College of Inner Mongolia UniversityOrdos 017000People's Republic of China Shenzhen College of Advanced Technology University of Chinese Academy of SciencesShenzhen 518055People's Republic of China Department of Chemical Engineering China University of PetroleumBeijing 102249People's Republic of China Department of Electronics Engineering The Chinese University of Hong KongHong Kong 999077People's Republic of China School of Materials Science and Engineering Georgia Institute of TechnologyAtlantaGeorgia 30332USA

As modern electronics are developed towards miniaturisation,high-degree integration and intelligentisation,a large amount of heat will be generated during the operation of devices.How to efficiently remove needless heat is becoming more and more crucial for the lifetime and performance of electronic devices.Many efforts have been made to improve the thermal conductivity of polymer composites,which is an important component of electronics.Herein,the authors report on preparation of boron nitride micosphere/epoxy composites.The cross-plane thermal conductivity of the resultant composites is up to 1.03 Wm‒1K‒1.This is attributed to the thermally conductive network formed by the peeled hexagonal boron nitride flakes.Thanks to the superior thermal stability of boron nitride micosphere,the boron nitride micosphere/epoxy composite shows a decreased coefficient of thermal expansion(53.47 ppm/K)and an increased glass transition temperature(147.2℃)compared with the pure epoxy resin.In addition,the boron nitride micosphere/epoxy composite exhibits a lower dielectric constant compared with that of the hexagonal boron nitride/epoxy composite.This strategy can potentially pave the way for the design and fabrication of materials with high cross-plane thermal conductivity and lower dielectric properties.

关键词： composites composite conductivity

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Microstructure and mechanical properties of novel Al-Y-Sc alloys with high thermal stability and electrical conductivity

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Journal of Materials Science & Technology 2020年第1期36卷 1-6页

作者： A.V.Pozdniakov R.Yu.Barkov NUST"MISiS" Leninskiy ave.4119049MoscowRussia

The microstructure and mechanical properties of novel Al-Y-Sc alloys with high thermal stability and electrical conductivity were investigated.Eutectic Al3 Y-phase particles of size 100-200 nm were detected in the as-cast microstructure of the alloys.Al3 Y-phase particles provided a higher hardness to as cast alloys than homogenized alloys in the temperature range of 370-440℃.L12 precipitates of the Al3(ScxYy) phase were nucleated homogenously within the aluminium matrix and heterogeneously on the dislocations during annealing at 400℃.The average size of the L12 precipitates was 11±2 nm after annealing for 1 h,and 25-30 nm after annealing for 5 h,which led to a decrease in the hardness of the Al-0.2 Y-0.2 Sc alloy to15 HV.The recrystallization temperature exceeded 350℃and 450℃for the Al-0.2 Y-0.05 Sc and Al-0.2 Y-0.2 Sc alloys,respectively.The investigated alloys demonstrated good thermal stability of the hardness and tensile properties after annealing the rolled alloys at 200 and 300℃,due to fixing of the dislocations and grain boundaries by L12 precipitates and eutectic Al3 Y-phase particles.The good combination of strength,plasticity,and electrical conductivity of the investigated Al-0.2 Y-0.2 Sc alloys make it a promising candidate for electrical conductors.The alloys exhibited a yield stress of 177-183 MPa,ultimate tensile stress of 199-202 MPa,elongation of 15.2-15.8%,and electrical conductivity of 60.8%-61.5% IACS.

关键词： Aluminium alloys Scandium Yttrium Recrystallization Mechanical properties Electrical conductivity

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High-entropy pyrochlores with low thermal conductivity for thermal barrier coating materials

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Journal of Advanced Ceramics 2019年第4期8卷 576-582页

作者： Fei LI Lin ZHOU Ji-Xuan LIU Yongcheng LIANG Guo-Jun ZHANG State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and Engineering Institute of Functional Materials College of ScienceDonghua University

High-entropy pyrochlore-type structures based on rare-earth zirconates are successfully produced by conventional solid-state reaction method. Six rare-earth oxides(La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, and Y2O3) and ZrO2 are used as the raw powders. Five out of the six rare-earth oxides with equimolar ratio and ZrO2 are mixed and sintered at different temperatures for investigating the reaction process. The results demonstrate that the high-entropy pyrochlores(5RE1/5)2 Zr2O7 have been formed after heated at 1000 ℃. The(5RE1/5)2Zr2O7 are highly sintering resistant and possess excellent thermal stability. The thermal conductivities of the(5RE1/5)2Zr2O7 high-entropy ceramics are below 1 W·m–1·K–1 in the temperature range of 300–1200 ℃. The(5RE1/5)2Zr2O7 can be potential thermal barrier coating materials.

关键词： thermal barrier coating(TBC) pyrochlore high-entropy ceramics thermal conductivity

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Effect of Deformation and Aging Treatment on Electrical conductivity of Cu-Cr Alloy

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Journal of Rare Earths 2005年第S1期23卷 419-422页

作者：孙光颖 College of Mathematics and Physics Yanshan University Qinhuangdao 066004 China

The effect of deformation and aging treatment on the electrical conductivity of Cu-Cr alloy was studied. The results show that deformation can reduce the electrical conductivity of Cu-Cr alloy, but deformation followed by optimum aging treatment can effectively improve the electrical conductivity of Cu-Cr alloy, under the condition of 0～70% deformation, and the electrical conductivity of Cu-Cr alloy by aging treatment increases and the aging time of obtaining much better electrical conductivity of Cu-Cr alloy decreases with increase in deformation quantity of Cu-Cr alloy. The best electrical conductivity of Cu-Cr alloy after deformation can be obtained by aging treatment at 500 ℃. And also the reasons for the variations of alloy's electrical conductivity and the function of adding RE were analyzed.

关键词： Cu-Cr alloy deformation and aging treatment conductivity rare earths

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