Zinc oxide hexagonal tubular crystals were synthesized by direct microwave heating from ZnO powders within 5 min without any metal catalysts or transport agents. ZnO source materials were evaporated from the high-temp...
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Zinc oxide hexagonal tubular crystals were synthesized by direct microwave heating from ZnO powders within 5 min without any metal catalysts or transport agents. ZnO source materials were evaporated from the high-temperature zone in an enclosure, and crystals were grown on the self-source substrate in an appropriate condition. The ZnO vapor formed in the high-temperature zone can deposit and grow on the powders located in the low-temperature zone to form crystals. The scanning electron microscopy （SEM） reveals that these products are hexagonal tube crystals with 80 ~rn in diameter and 250 μm in length, having a well faceted end and side surface. A possible growth mechanism and the influence of reaction temperature on the formation of crystalline ZnO hexagonal tubes were presented. The photoluminescence （PL） exhibits strong ultraviolet emission at room temperature, indicating the potential applications in short-wave light-emitting photonic devices.
A 3-D finite element model of two-stage thermoelectric generator based on low-temperature thermoelectric material bismuth-telluride and medium-temperature thermoelectric material skutterudites is established. Based on...
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ISBN:
(纸本)9781424480364
A 3-D finite element model of two-stage thermoelectric generator based on low-temperature thermoelectric material bismuth-telluride and medium-temperature thermoelectric material skutterudites is established. Based on the formal model, structural optimization of the two-stage thermoelectric generator is carried out. Results show that, reasonable design of the structure of two-stage thermoelectric generator can take full advantage of the characteristics of thermoelectric materials and effectively improve the performance of power generation. If contact resistance and all heat losses are neglected, the conversion efficiency of the two-stage thermoelectric generator can reach a value of 17.02%.
Polyaniline nanopaticles for supercapacitor were prepared by using polystyrene microsphere as carrier. They were characterized by FTIR, SEM and TGA for structure and electrochemical station for supercapacitive perform...
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Research work of wire extension control with Dual freedom PID controller in pulsed MIG welding process of aluminum alloy. In the condition of optimum parameters, the simulations were firstly completed by separately us...
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ISBN:
(纸本)9781424494361
Research work of wire extension control with Dual freedom PID controller in pulsed MIG welding process of aluminum alloy. In the condition of optimum parameters, the simulations were firstly completed by separately using Routine PID control and Dual freedom PID control, based on designing the wire speed of wire extension step response and gaining identification model. Based on the results of simulation using Matlab/Simulink, the experimental research on aluminum alloy pulsed MIG welding by using Dual freedom PID control was carried out in the real-time target environment with XPC Target. In the pulsed MIG welding process of aluminum alloy, the results prove that the Dual freedom PID control can bring higher precision and quicker response speed, efficiently control the stability of wire extension, and satisfy the stability of welding process.
A real-time synchronous acquisition and control system was designed to meet the requirements of measurement and control for pulsed MIG welding process of aluminum alloy using virtual instrument design software LabVIEW...
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A real-time synchronous acquisition and control system was designed to meet the requirements of measurement and control for pulsed MIG welding process of aluminum alloy using virtual instrument design software LabVIEW. Considering the characteristics of pulsed MIG welding, development efficiency and control response time, the mode of "data acquisition card+ PC+ real-time controller" was adopted and the parallel processing of voltage, current and vision signals was realized with complex signal processing algorithm based on hardware platform and COM technology. The test results show that the developed platform can acquire and process the information real-timely and effectively in pulsed MIG welding process of aluminum alloy and also has friendly program interface and good expansibility.
The performance of composite ceramic armor penetrated by rod projectile was studied by both numerical simulation and *** penetration and damage mechanisms of the projectile-armor after high-speed collision were also o...
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The performance of composite ceramic armor penetrated by rod projectile was studied by both numerical simulation and *** penetration and damage mechanisms of the projectile-armor after high-speed collision were also observed by high-speed *** experimental results showed that the ballistic performance of composite ceramic armor was highly affected by the density,hardness and toughness of bulletproof *** flow stress of the failed bulletproof ceramic is not only related to the pressure but also related to the strain *** phenomenological method based on Bodner-Partom ceramic model was introduced to derive the growth rate of *** simulation results show good agreement with the experimental results.
The effects of activated sintering technology of H2 atmosphere sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying calcining-continuous red...
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The effects of activated sintering technology of H2 atmosphere sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying calcining-continuous reduction technology were *** experimental results showed that W-15Cu alloy,consolidated by activated sintering technology of H2 atmosphere sintering for 1 h at 1300 ℃,with 98.5 % relative density,transverse rupture strength 1218 MPa,Vickers hardness HV0.5 378,average grain size about 1.2 μm and thermal conductivity 192 W/m·K,was *** comparison to the normal sintering process,activated sintering process to W-15Cu alloy could be achieved at lower sintering ***,better properties in activated sintered compacts were obtained,and activated sintering process resulted in finer microstructure and excellent properties.
Low or zero thermal expansion porous ceramics are required for several applications. In this work near zero thermal expansion porous ceramics were fabricated by using SiC and ZrW2O8 as positive and negative thermal ex...
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Low or zero thermal expansion porous ceramics are required for several applications. In this work near zero thermal expansion porous ceramics were fabricated by using SiC and ZrW2O8 as positive and negative thermal expansion materials, respectively, bonded by soda lime glass. The mixture of SiC, ZrW2O8 and soda lime glass was sintered by Pulsed Electric Current Sintering (PECS, or sometimes called Spark Plasma Sintering, SPS) at 700°C. Sintered samples with ZrW2O 8 particle size smaller than 25 μm have high thermal expansion coefficient, because ZrW2O8 has the reaction with soda lime glass to form Na2ZrW3O12 during sintering process. The reaction between soda lime glass and ZrW2O8 is reduced by increasing particle size of ZrW2O8. Sintered sample with ZrW2O8 particle size 45-90 μm shows near zero thermal expansion.
Both in-phase and anti-phase two-soliton bound states were observed in a carbon-nanotube based mode-locked fiber laser. This paper also reports preliminary results of bound states with graphene as the saturable absorb...
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ISBN:
(纸本)9780977565771
Both in-phase and anti-phase two-soliton bound states were observed in a carbon-nanotube based mode-locked fiber laser. This paper also reports preliminary results of bound states with graphene as the saturable absorber for the first time.
作者：
Xingguo FengMingren SunGnangze TangXinxin MaSchool of Materials Science and Engineering
Harbin Institute of TechnologyHarbin 150001China National Key Laboratory of Science and Technology on Precision Hot Processing of MetalsHarbin Institute of TechnologyHarbin 150001China State Key Laboratory of Advanced Welding and JoiningHarbin Institute of Technology Harbin 150001China
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