Evacuated tube transportation （ETT） will be one of the ultra-large-scale vacuum application areas. This paper lists some key vacuum technology issues in ETT： （1） how to construct ultra-large-scale vacuum chamber ...Evacuated tube transportation （ETT） will be one of the ultra-large-scale vacuum application areas. This paper lists some key vacuum technology issues in ETT： （1） how to construct ultra-large-scale vacuum chamber with lower cost and high reliability, （2） how to evacuate gas out of the ETT tube in short time, （3） how to release heat or reduce temperature in the vacuum tube, （4） how to avoid vacuum discharge, （5） how to make vehicles with airproof shells and life support system, and （6） how to detect leaks and find leak positions efficiently. At the same time, some solutions are proposed.展开更多
Recovery of Ni-Cd batteries was studied by a self-designed vacuum-aided recovering system under laboratory conditions. The fundamental research on a process of disassembling and recovering selected materials from Ni-C...Recovery of Ni-Cd batteries was studied by a self-designed vacuum-aided recovering system under laboratory conditions. The fundamental research on a process of disassembling and recovering selected materials from Ni-Cd batterieswas conducted. The impacts of temperature, pressure and time were studied respectively. The mechanism of vacuum thermal recovering was also discussed. The results show that: Ni-Cd batteries can be recovered effectively byvacuum-aided recovering system at 573~1173 K. At constant pressure, the increase of temperature can improve theseparating efficiency of cadmium. When the temperature is 1173 K, the cadmium can evaporate completely fromthe residue during 3 h at 10 Pa. The reduction of pressure in the certain range is effective to separate cadmium byvacuum distillation. Distillation time is a very important factor affecting separation of cadmium.展开更多
The evaporation coefficients alpha(i) of impurity elements Al, Cu, Cr, Co, Fe, Ni, Si in liquid scandium metal of purity 99.9% were measured at 1550 degrees C and 6.7 x 10(-3) Pa. The separating coefficients beta(i) a...The evaporation coefficients alpha(i) of impurity elements Al, Cu, Cr, Co, Fe, Ni, Si in liquid scandium metal of purity 99.9% were measured at 1550 degrees C and 6.7 x 10(-3) Pa. The separating coefficients beta(i) and activity coefficients gamma(i)(o) of these impurity elements were calculated and the separation possibility between these impurity elements and Sc was discussed from thermodynamics. Then the new technology in preparation of high purity scandium metal was proposed and its purification mechanism was discussed.展开更多
Even though switching in vacuum is a technology with almost 100 years of history,its recent develop-ments are still changing the future of power transmission and distribution systems.First,current switch-ing in vacuum...Even though switching in vacuum is a technology with almost 100 years of history,its recent develop-ments are still changing the future of power transmission and distribution systems.First,current switch-ing in vacuum is an eco-friendly technology compared to switching in SF 6 gas,which is the strongest greenhouse gas according to the Kyoto Protocol.Vacuum,an eco-friendly natural medium,is promising for reducing the usage of SF 6 gas in current switching in transmission voltage.Second,switching in vacuum achieves faster current interruption than existing alternating current(AC)switching technolo-gies.A vacuum circuit breaker(VCB)that uses an electromagnetic repulsion actuator is able to achieve a theoretical limit of AC interruption,which can interrupt a short-circuit current in the first half-cycle of a fault current,compared to the more common three cycles for existing current switching technologies.This can thus greatly enhance the transient stability of power networks in the presence of short-circuit faults,especially for ultra-and extra-high-voltage power transmission lines.Third,based on fast vacuum switching technology,various brilliant applications emerge,which are benefiting the power systems.They include the applications in the fields of direct current(DC)circuit breakers(CBs),fault current lim-iting,power quality improvement,generator CBs,and so forth.Fast vacuum switching technology is promising for controlled switching technology in power systems because it has low variation in terms of opening and closing times.With this controlled switching,vacuum switching technology may change the“gene”of power systems,by which power switching transients will become smoother.展开更多
研究采用真空感应气雾化(Vacuum Induction Gas Atomization,VIGA)技术制备GH4169合金粉末,系统探究气体温度对粉末特性的影响规律。结果表明,随着气体温度从100℃升高到600℃,粉末的粒度分布明显向左移动,D50由75μm减小到42μm。扫描...研究采用真空感应气雾化(Vacuum Induction Gas Atomization,VIGA)技术制备GH4169合金粉末,系统探究气体温度对粉末特性的影响规律。结果表明,随着气体温度从100℃升高到600℃,粉末的粒度分布明显向左移动,D50由75μm减小到42μm。扫描电子显微镜(Scanning Electron Microscope,SEM)分析表明,较高气体温度有助于提高粉末的球形度,减少卫星粉的生成。X射线衍射(X-Ray Diffraction,XRD)分析揭示,气体温度对粉末的物相组成影响不大,但是较高温度下粉末具有更高的结晶度和更大的晶粒尺寸。此外,粉末的流动性随气体温度的升高而显著改善。展开更多
基金provided by National Natural Science Foundation of China (No.50678152)Scientific Plan Fund of Shaanxi Province (No.2009K09-24)
文摘Evacuated tube transportation （ETT） will be one of the ultra-large-scale vacuum application areas. This paper lists some key vacuum technology issues in ETT： （1） how to construct ultra-large-scale vacuum chamber with lower cost and high reliability, （2） how to evacuate gas out of the ETT tube in short time, （3） how to release heat or reduce temperature in the vacuum tube, （4） how to avoid vacuum discharge, （5） how to make vehicles with airproof shells and life support system, and （6） how to detect leaks and find leak positions efficiently. At the same time, some solutions are proposed.
文摘Recovery of Ni-Cd batteries was studied by a self-designed vacuum-aided recovering system under laboratory conditions. The fundamental research on a process of disassembling and recovering selected materials from Ni-Cd batterieswas conducted. The impacts of temperature, pressure and time were studied respectively. The mechanism of vacuum thermal recovering was also discussed. The results show that: Ni-Cd batteries can be recovered effectively byvacuum-aided recovering system at 573~1173 K. At constant pressure, the increase of temperature can improve theseparating efficiency of cadmium. When the temperature is 1173 K, the cadmium can evaporate completely fromthe residue during 3 h at 10 Pa. The reduction of pressure in the certain range is effective to separate cadmium byvacuum distillation. Distillation time is a very important factor affecting separation of cadmium.
文摘The evaporation coefficients alpha(i) of impurity elements Al, Cu, Cr, Co, Fe, Ni, Si in liquid scandium metal of purity 99.9% were measured at 1550 degrees C and 6.7 x 10(-3) Pa. The separating coefficients beta(i) and activity coefficients gamma(i)(o) of these impurity elements were calculated and the separation possibility between these impurity elements and Sc was discussed from thermodynamics. Then the new technology in preparation of high purity scandium metal was proposed and its purification mechanism was discussed.
基金supported in part by the National Natural Science Foundation of China (51937009 and 51877166)the Key Research and Development Program of Shaanxi Province (2019ZDLGY18-04)
文摘Even though switching in vacuum is a technology with almost 100 years of history,its recent develop-ments are still changing the future of power transmission and distribution systems.First,current switch-ing in vacuum is an eco-friendly technology compared to switching in SF 6 gas,which is the strongest greenhouse gas according to the Kyoto Protocol.Vacuum,an eco-friendly natural medium,is promising for reducing the usage of SF 6 gas in current switching in transmission voltage.Second,switching in vacuum achieves faster current interruption than existing alternating current(AC)switching technolo-gies.A vacuum circuit breaker(VCB)that uses an electromagnetic repulsion actuator is able to achieve a theoretical limit of AC interruption,which can interrupt a short-circuit current in the first half-cycle of a fault current,compared to the more common three cycles for existing current switching technologies.This can thus greatly enhance the transient stability of power networks in the presence of short-circuit faults,especially for ultra-and extra-high-voltage power transmission lines.Third,based on fast vacuum switching technology,various brilliant applications emerge,which are benefiting the power systems.They include the applications in the fields of direct current(DC)circuit breakers(CBs),fault current lim-iting,power quality improvement,generator CBs,and so forth.Fast vacuum switching technology is promising for controlled switching technology in power systems because it has low variation in terms of opening and closing times.With this controlled switching,vacuum switching technology may change the“gene”of power systems,by which power switching transients will become smoother.
文摘研究采用真空感应气雾化(Vacuum Induction Gas Atomization,VIGA)技术制备GH4169合金粉末,系统探究气体温度对粉末特性的影响规律。结果表明,随着气体温度从100℃升高到600℃,粉末的粒度分布明显向左移动,D50由75μm减小到42μm。扫描电子显微镜(Scanning Electron Microscope,SEM)分析表明,较高气体温度有助于提高粉末的球形度,减少卫星粉的生成。X射线衍射(X-Ray Diffraction,XRD)分析揭示,气体温度对粉末的物相组成影响不大,但是较高温度下粉末具有更高的结晶度和更大的晶粒尺寸。此外,粉末的流动性随气体温度的升高而显著改善。
