The inductive cold crucible is a very interesting tool for processing materials by magnetic field without pollution.It is more and more used in various areas like in aeronautic,photovoltaic,waste recycling industries ...The inductive cold crucible is a very interesting tool for processing materials by magnetic field without pollution.It is more and more used in various areas like in aeronautic,photovoltaic,waste recycling industries and also for medical applications.As the cold cracible in its current state of art has a low energetic efficiency,the better comprehension of this process thanks to recently improved multiphysic modeling tools and experimental measurements gives some guidelines for experimenting new kinds of cold crucibles.These elements are presented in this paper, especially the numerical modeling and first tests operated on a'thin shaped cold crucible'which seems very promising concerning the efficiency improvement and also a better overheating of liquid charge.展开更多
Some transition metal antimonides were prepared by levitation melting and subsequent ball-milling. The electrochem-ical behaviors of these materials as new candidate negative electrode materials in lithium ion seconda...Some transition metal antimonides were prepared by levitation melting and subsequent ball-milling. The electrochem-ical behaviors of these materials as new candidate negative electrode materials in lithium ion secondary batteries wereinvestigated. It was found that they exhibited significantly larger volumetric capacity than carbon-based materi-als. The formation and composition of solid electrolyte interface (SEI) film were characterized by electrochemicalimpedance spectroscopy (EIS) and Fourier transform infra-red (FTIR) spectroscopy.展开更多
Zr1-xTixNiSn0.975Sb0.025 （x=0, 0.15, 0.25, 0.5） half-Heusler thermoelectric materials have been prepared by levitation melt, melt spinning and hot pressing. X-ray diffraction analysis and scanning electron microscop...Zr1-xTixNiSn0.975Sb0.025 （x=0, 0.15, 0.25, 0.5） half-Heusler thermoelectric materials have been prepared by levitation melt, melt spinning and hot pressing. X-ray diffraction analysis and scanning electron microscopy observation showed that nearly single phase half-Heusler compounds were obtained for the levitation-melted ingots. The effects of Ti substitution and grain refinement by melt spinning have been studied. It is found that both the Ti substitution on the Zr site and the grain refinement can reduce the lattice thermal conductivity and total thermal conductivity. The maximum figure of merit ZT value achieved is about 0.47, which is comparable with the previously reported value of ,-0.5 for Zr0.5Ti0.5NiSn.展开更多
Based on the power dissipating model of spherical sample in free convection gas medium and the expression of input power, the model of temperature calculation for electromagnetic levitation melting sample was establis...Based on the power dissipating model of spherical sample in free convection gas medium and the expression of input power, the model of temperature calculation for electromagnetic levitation melting sample was established. Considering the limitation of levitation force and levitation sample temperature,the principle of stability levitation zone computation was determined. A spherical sample （ThDy）Fe2 under the protection of argon gas was examined, and the effect of radius of levitation sample and perturbation on the stable levitation zone was investigated. The results show that longitudinal perturbation and transverse perturbation can shorten the length of stable levitation zone and the range of levitation sample radius. By increasing the sample radius and weakening the perturbation the electromagnetic levitation melting stability of sample can be improved.展开更多
Half-Heusler(HH)alloys constitute an important class of materials that exhibit promising potential in high-temperature thermoelectric(TE)power generation.In this work,we synthesized Zr_(1−x)Yb_(x)NiSn(x=0,0.01,0.02,0....Half-Heusler(HH)alloys constitute an important class of materials that exhibit promising potential in high-temperature thermoelectric(TE)power generation.In this work,we synthesized Zr_(1−x)Yb_(x)NiSn(x=0,0.01,0.02,0.04,0.06 and 0.10)HH alloys using a time-efficient levitation melting and spark plasma sintering procedure.X-ray diffraction showed that the samples were predominantly single phased,and that the lattice constant increased systematically with increasing Yb doping ratio.The doping effects of Yb on the thermoelectric properties were studied.It was found that Yb doping consistently decreased the electrical and thermal conductivities.On the other hand,the effects of Yb doping on the Seebeck coefficient were found to be non-monotonic.The magnitude of the Seebeck coefficient(n-type)was increased upon Yb doping up to x=0.02,above which Yb doping introduced notable p-type conduction.As a result,the room-temperature Seebeck coefficient of the x=0.10 sample became positive although the magnitude was not high.The thermoelectric figure of merit,ZT,reached a maximum of∼0.38 at 900 K for the x=0.01 sample.Selective doping on the Ni and Sn sites are necessary to further optimize the TE performance of Zr_(1−x)Yb_(x)NiSn alloys.展开更多
文摘The inductive cold crucible is a very interesting tool for processing materials by magnetic field without pollution.It is more and more used in various areas like in aeronautic,photovoltaic,waste recycling industries and also for medical applications.As the cold cracible in its current state of art has a low energetic efficiency,the better comprehension of this process thanks to recently improved multiphysic modeling tools and experimental measurements gives some guidelines for experimenting new kinds of cold crucibles.These elements are presented in this paper, especially the numerical modeling and first tests operated on a'thin shaped cold crucible'which seems very promising concerning the efficiency improvement and also a better overheating of liquid charge.
基金This work is supported by the N ational Natural Science Foundation of China(No.50201014)RFDP of the Education Ministry of China(No.20010335045).
文摘Some transition metal antimonides were prepared by levitation melting and subsequent ball-milling. The electrochem-ical behaviors of these materials as new candidate negative electrode materials in lithium ion secondary batteries wereinvestigated. It was found that they exhibited significantly larger volumetric capacity than carbon-based materi-als. The formation and composition of solid electrolyte interface (SEI) film were characterized by electrochemicalimpedance spectroscopy (EIS) and Fourier transform infra-red (FTIR) spectroscopy.
基金supported by the National High Technology Research and Development Program of China("863 Program", No 2007AA03Z234)the National Basic Research Program of China (No 2007CB607502)the National Natural Science Foundation of China (No50601022)
文摘Zr1-xTixNiSn0.975Sb0.025 （x=0, 0.15, 0.25, 0.5） half-Heusler thermoelectric materials have been prepared by levitation melt, melt spinning and hot pressing. X-ray diffraction analysis and scanning electron microscopy observation showed that nearly single phase half-Heusler compounds were obtained for the levitation-melted ingots. The effects of Ti substitution and grain refinement by melt spinning have been studied. It is found that both the Ti substitution on the Zr site and the grain refinement can reduce the lattice thermal conductivity and total thermal conductivity. The maximum figure of merit ZT value achieved is about 0.47, which is comparable with the previously reported value of ,-0.5 for Zr0.5Ti0.5NiSn.
文摘Based on the power dissipating model of spherical sample in free convection gas medium and the expression of input power, the model of temperature calculation for electromagnetic levitation melting sample was established. Considering the limitation of levitation force and levitation sample temperature,the principle of stability levitation zone computation was determined. A spherical sample （ThDy）Fe2 under the protection of argon gas was examined, and the effect of radius of levitation sample and perturbation on the stable levitation zone was investigated. The results show that longitudinal perturbation and transverse perturbation can shorten the length of stable levitation zone and the range of levitation sample radius. By increasing the sample radius and weakening the perturbation the electromagnetic levitation melting stability of sample can be improved.
基金supported by the Nature Science Foundation of China(Grant Nos.51171171 and 50971115)the National Basic Research Program of China(Grant No.2007CB607502)J.H.would like to thank the support by the National Science Foundation of the United States(Grant No.1008073).
文摘Half-Heusler(HH)alloys constitute an important class of materials that exhibit promising potential in high-temperature thermoelectric(TE)power generation.In this work,we synthesized Zr_(1−x)Yb_(x)NiSn(x=0,0.01,0.02,0.04,0.06 and 0.10)HH alloys using a time-efficient levitation melting and spark plasma sintering procedure.X-ray diffraction showed that the samples were predominantly single phased,and that the lattice constant increased systematically with increasing Yb doping ratio.The doping effects of Yb on the thermoelectric properties were studied.It was found that Yb doping consistently decreased the electrical and thermal conductivities.On the other hand,the effects of Yb doping on the Seebeck coefficient were found to be non-monotonic.The magnitude of the Seebeck coefficient(n-type)was increased upon Yb doping up to x=0.02,above which Yb doping introduced notable p-type conduction.As a result,the room-temperature Seebeck coefficient of the x=0.10 sample became positive although the magnitude was not high.The thermoelectric figure of merit,ZT,reached a maximum of∼0.38 at 900 K for the x=0.01 sample.Selective doping on the Ni and Sn sites are necessary to further optimize the TE performance of Zr_(1−x)Yb_(x)NiSn alloys.
