Semi-solid powder rolling（SSPR） is a novel strip manufacturing process,which includes the features of semi-solid rolling and powder rolling.In this work,densification process and deformation mechanisms of B4 C and A...Semi-solid powder rolling（SSPR） is a novel strip manufacturing process,which includes the features of semi-solid rolling and powder rolling.In this work,densification process and deformation mechanisms of B4 C and AA2024 mixed powders in the presence of liquid phase were investigated.The relationships between relative densities and rolling forces were analyzed as well.The results show that liquid fraction plays an important role in the densification process which can be divided into three stages.Rolling deformation is the main densification mechanism in deformation area when the liquid fraction is lower than 20%.When the liquid fraction is equal to or higher than 20%,the flowing and filling of liquid phase are the densification mechanisms in deformation area.The relative densities increase with increasing rolling forces.The relative density–rolling force curves are similar at 550 °C and 585 °C.The characteristics of the curve shapes are apparently different at 605 °C and 625 °C.展开更多
Using coal tar pitch as a matrix precursor to prepare carbon materials is widelyused by impregnation/carbonization processing technology.Four different grades of coaltar pitch and a natural pitch were characterized in...Using coal tar pitch as a matrix precursor to prepare carbon materials is widelyused by impregnation/carbonization processing technology.Four different grades of coaltar pitch and a natural pitch were characterized in terms of carbon yield, density, viscosity,and fractionation with solvents, as well as by thermal analysis methods.The suitability ofthese commercially available matrices for densification of 3 dimensional carbon-carboncomposites was examined.The theoretical results compared with experimental results.The highest density after impregnation was obtained using one of the coal tar pitches.Thepredicted results are in reasonable agreement with experiment data.The significance ofthis research is that a special heat treatment regime was conducted.The effects of modificationtemperature on the densification efficiency of composites were investigated andthen structure and characteristics of the composites were determined by scanning electronmicroscopy (SEM), Transmission electron microscopy (TEM) and X-Ray Diffraction (XRD).展开更多
Fabrication of flexible organic light-emitting diodes（FOLEDs） with ITO/PVK:TPD/Alq3/Al configuration prepared on PET substrates is reported.Alq3 is used as the light-emitting material.The curves of the current densi...Fabrication of flexible organic light-emitting diodes（FOLEDs） with ITO/PVK:TPD/Alq3/Al configuration prepared on PET substrates is reported.Alq3 is used as the light-emitting material.The curves of the current density vs.voltage,optical current vs.voltage and quantum efficiency vs.current density of the devices are investigated.Compared the devices with the ones that have the same configuration and are fabricated under the same conditions but on glass substrates,the characteristics of the two kinds of devices are very similar except that the threshold voltage of the flexible FOLEDs is a little higher.Under the driving voltage of 20V,the corresponding brightness and the external quantum efficiency are 1000 cd/m2 and 0.27%,respectively.In addition,the anti-bend ability of the devices is tested and the reasons of failure of the devices are analyzed.展开更多
Supercapacitors are expected to bridge the gap between conventional electrostatic capacitors and batteries, but have not found significant application in primary energy devices, partly due to some unsolved problems in...Supercapacitors are expected to bridge the gap between conventional electrostatic capacitors and batteries, but have not found significant application in primary energy devices, partly due to some unsolved problems in the elec- trode materials. A wide range of novel materials such as novel carbons have been investigated to increase the energy den- sity of the electrodes and the volumetric merits of the materi- als need to be specifically considered and evaluated, towards the practical application of these novel materials. In obser- vation of the intense research activity to improve the volu- metric performance of carbon electrodes, the density or mass loading is particularly important and shall be further opti- mized, both for commercially applied activated carbons and in novel carbon electrode materials such as graphene. In this review, we presented a brief overview of the recent progress in improving the volumetric performance of carbon-based su- percapacitor electrodes, particularly highlighting the devel- opment of densified electrodes by various technical strategies including the controlled assembly of carbon building blocks, developing carbon based hybrid composites and constructing micro- supercapacitors.展开更多
Dielectric elastomer actuators(DEAs) have attracted much interest over the past decades due to the inherent flexibility, large strain, high efficiency, high energy density, and fast response of the material, which are...Dielectric elastomer actuators(DEAs) have attracted much interest over the past decades due to the inherent flexibility, large strain, high efficiency, high energy density, and fast response of the material, which are known as one of the most promising candidates for artificial muscle. In this paper, we first introduce the actuation principle and electromechanical modeling approaches of dielectric elastomers(DEs). Then, the performance of different DEs material and existing compliant electrodes that are widely utilized for DEAs are presented. We also highlight the compatibility of DEs, which is suitable for a variety of actuator designs and applications. Lastly, we summarize the challenges and future development in terms of electromechanical modeling, improvement of materials including compliant electrodes and dielectric elastomer, designs and applications of novel dielectric elastomer actuators.展开更多
Giant magnetostrictive materials are a kind of functional materials developed since 1970s, known as their large magnetostrain and high energy density. In this paper, an introduction of magnetostriction and the history...Giant magnetostrictive materials are a kind of functional materials developed since 1970s, known as their large magnetostrain and high energy density. In this paper, an introduction of magnetostriction and the history of magnetostrictive materials are described firstly. Then we review the recent developments of both rare earth and non-rare earth magnetostrictive materials. Finally, the tendency of developing new giant magnetostrictive materials is presented.展开更多
W-Ag has applications in a wide range of cutting-edge fields,counting heat sinks and microwave absorbers for micro—electronic components,electric arc ends,and filaments for welding processes,electrical contacts,and d...W-Ag has applications in a wide range of cutting-edge fields,counting heat sinks and microwave absorbers for micro—electronic components,electric arc ends,and filaments for welding processes,electrical contacts,and durable electronic connections.Chemical methods provide a number of benefits,including improved purity,and controlled particle size.The present study focused on the fabrication of W-Ag nano composites using chemical synthesis.W-Ag nanocomposites with average size less than 50 nm were synthesized using Tungsten hexacarbonyl(W(CO)_(6),and silver acetate(CH_(3)-COOAg)as metal precursors in the present study.The W-Ag composites were sintered using conventional sintering.X-ray diffraction studies of as-prepared powders showed amorphous W-phase and FCC Ag,while sintered W-Ag composites exhibited crystalline BCC W and FCC Ag phase.The effect of sintering temperature on relative density and mechanical properties of W-Ag sintered compacts was investigated.Relative density in excess of 97.6%,98.2%and 98.8%was achieved for W-20.3 wt.%Ag,W-30.1 wt.%Ag and W-39.8 wt.%Ag composites on conventional sintering at 1000℃ for 1 h.Vickers hardness of 364±10 and 320±8 Hv and 279±6 were achieved for W-20.3 wt.%Ag,W-30.1 wt.%Ag and W-39.8 wt.%Ag composite compacts respectively.The hardness value of W-Ag composites decreased with an increase in Ag content.The combination of properties realized in this study renders the composites suitable for automotive and heat sink applications.展开更多
基金Project(2013KJCX0014)supported by the Key Project of Department of Education of Guangdong Province,China
文摘Semi-solid powder rolling（SSPR） is a novel strip manufacturing process,which includes the features of semi-solid rolling and powder rolling.In this work,densification process and deformation mechanisms of B4 C and AA2024 mixed powders in the presence of liquid phase were investigated.The relationships between relative densities and rolling forces were analyzed as well.The results show that liquid fraction plays an important role in the densification process which can be divided into three stages.Rolling deformation is the main densification mechanism in deformation area when the liquid fraction is lower than 20%.When the liquid fraction is equal to or higher than 20%,the flowing and filling of liquid phase are the densification mechanisms in deformation area.The relative densities increase with increasing rolling forces.The relative density–rolling force curves are similar at 550 °C and 585 °C.The characteristics of the curve shapes are apparently different at 605 °C and 625 °C.
文摘Using coal tar pitch as a matrix precursor to prepare carbon materials is widelyused by impregnation/carbonization processing technology.Four different grades of coaltar pitch and a natural pitch were characterized in terms of carbon yield, density, viscosity,and fractionation with solvents, as well as by thermal analysis methods.The suitability ofthese commercially available matrices for densification of 3 dimensional carbon-carboncomposites was examined.The theoretical results compared with experimental results.The highest density after impregnation was obtained using one of the coal tar pitches.Thepredicted results are in reasonable agreement with experiment data.The significance ofthis research is that a special heat treatment regime was conducted.The effects of modificationtemperature on the densification efficiency of composites were investigated andthen structure and characteristics of the composites were determined by scanning electronmicroscopy (SEM), Transmission electron microscopy (TEM) and X-Ray Diffraction (XRD).
文摘Fabrication of flexible organic light-emitting diodes（FOLEDs） with ITO/PVK:TPD/Alq3/Al configuration prepared on PET substrates is reported.Alq3 is used as the light-emitting material.The curves of the current density vs.voltage,optical current vs.voltage and quantum efficiency vs.current density of the devices are investigated.Compared the devices with the ones that have the same configuration and are fabricated under the same conditions but on glass substrates,the characteristics of the two kinds of devices are very similar except that the threshold voltage of the flexible FOLEDs is a little higher.Under the driving voltage of 20V,the corresponding brightness and the external quantum efficiency are 1000 cd/m2 and 0.27%,respectively.In addition,the anti-bend ability of the devices is tested and the reasons of failure of the devices are analyzed.
基金supported by the Chinese Government 1000 Plan Talent Programthe Ministry of Education's Program for New Century Excellent Talents in the University+2 种基金the National Natural Science Foundation of China(51322204)the Fundamental Research Funds for Central Universities(WK2060140014 and WK2060140017)the funding from Hefei National Synchrotron Radiation Lab
文摘Supercapacitors are expected to bridge the gap between conventional electrostatic capacitors and batteries, but have not found significant application in primary energy devices, partly due to some unsolved problems in the elec- trode materials. A wide range of novel materials such as novel carbons have been investigated to increase the energy den- sity of the electrodes and the volumetric merits of the materi- als need to be specifically considered and evaluated, towards the practical application of these novel materials. In obser- vation of the intense research activity to improve the volu- metric performance of carbon electrodes, the density or mass loading is particularly important and shall be further opti- mized, both for commercially applied activated carbons and in novel carbon electrode materials such as graphene. In this review, we presented a brief overview of the recent progress in improving the volumetric performance of carbon-based su- percapacitor electrodes, particularly highlighting the devel- opment of densified electrodes by various technical strategies including the controlled assembly of carbon building blocks, developing carbon based hybrid composites and constructing micro- supercapacitors.
基金supported by the National Natural Science Foundation of China(Grant Nos.51575187&91223201)Science and Technology Program of Guangzhou(Grant No.2014Y2-00217)+3 种基金Science and Technology Major Project of Huangpu District of Guangzhou(Grant No.20150000661)Research Project of State Key Laboratory of Mechanical System and Vibration(Grant No.MSV201405)the Fundamental Research Funds for the Central University(Grant No.2015ZZ007)the Natural Science Foundation of Guangdong Province(Grant No.S2013030013355)
文摘Dielectric elastomer actuators(DEAs) have attracted much interest over the past decades due to the inherent flexibility, large strain, high efficiency, high energy density, and fast response of the material, which are known as one of the most promising candidates for artificial muscle. In this paper, we first introduce the actuation principle and electromechanical modeling approaches of dielectric elastomers(DEs). Then, the performance of different DEs material and existing compliant electrodes that are widely utilized for DEAs are presented. We also highlight the compatibility of DEs, which is suitable for a variety of actuator designs and applications. Lastly, we summarize the challenges and future development in terms of electromechanical modeling, improvement of materials including compliant electrodes and dielectric elastomer, designs and applications of novel dielectric elastomer actuators.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50921003 and 50925101)the Fundamental Research Funds for the Central Universities
文摘Giant magnetostrictive materials are a kind of functional materials developed since 1970s, known as their large magnetostrain and high energy density. In this paper, an introduction of magnetostriction and the history of magnetostrictive materials are described firstly. Then we review the recent developments of both rare earth and non-rare earth magnetostrictive materials. Finally, the tendency of developing new giant magnetostrictive materials is presented.
文摘W-Ag has applications in a wide range of cutting-edge fields,counting heat sinks and microwave absorbers for micro—electronic components,electric arc ends,and filaments for welding processes,electrical contacts,and durable electronic connections.Chemical methods provide a number of benefits,including improved purity,and controlled particle size.The present study focused on the fabrication of W-Ag nano composites using chemical synthesis.W-Ag nanocomposites with average size less than 50 nm were synthesized using Tungsten hexacarbonyl(W(CO)_(6),and silver acetate(CH_(3)-COOAg)as metal precursors in the present study.The W-Ag composites were sintered using conventional sintering.X-ray diffraction studies of as-prepared powders showed amorphous W-phase and FCC Ag,while sintered W-Ag composites exhibited crystalline BCC W and FCC Ag phase.The effect of sintering temperature on relative density and mechanical properties of W-Ag sintered compacts was investigated.Relative density in excess of 97.6%,98.2%and 98.8%was achieved for W-20.3 wt.%Ag,W-30.1 wt.%Ag and W-39.8 wt.%Ag composites on conventional sintering at 1000℃ for 1 h.Vickers hardness of 364±10 and 320±8 Hv and 279±6 were achieved for W-20.3 wt.%Ag,W-30.1 wt.%Ag and W-39.8 wt.%Ag composite compacts respectively.The hardness value of W-Ag composites decreased with an increase in Ag content.The combination of properties realized in this study renders the composites suitable for automotive and heat sink applications.
