Three logarithmic linear equations between D_(Me)^(V/L) and [m_(NaCl)], and the relationship of D_(Me)^(V/L) versus F/Cl or K/Na mole ratios have been established by the experiments of the partitioning of Pb and Zn be...Three logarithmic linear equations between D_(Me)^(V/L) and [m_(NaCl)], and the relationship of D_(Me)^(V/L) versus F/Cl or K/Na mole ratios have been established by the experiments of the partitioning of Pb and Zn between granitic silicate melt and aqueous fluid. These results have been used to quantitatively study some essential problems, such as the possibility and degree of Pb-Zn mineralization in the system of granitic magma and hydrothermal fluid, and the influence of the relative contents of alkali and volatiles on the Pb-Zn mineralization in the same system. Some new points have been put forward in this paper.展开更多
Actually recent investigation in developing semiconducting-superconducting composites based in CdS and Bi-based superconductors has attracted interest in processing thin superconducting films. In this work are reporte...Actually recent investigation in developing semiconducting-superconducting composites based in CdS and Bi-based superconductors has attracted interest in processing thin superconducting films. In this work are reported Bi-Pb-Sr-Ca-Cu-O (BPSCCO) thin films grown on MgO substrates by spray pyrolysis technique from a solution containing Bi(NO3)3, Pb(NO3)2, Sr(NO3)2, Ca(NO3)2 and Cu(NO3)2, with a subsequent solid state reaction for growing the Bi-based superconducting phases. Annealed films were characterized by X-ray diffraction, atomic absorption spectroscopy and resistance measurements. Interdependence between Pb content, annealing time and temperature, in the formation of superconducting phases was studied applying a fractional factorial design 3III4-2. Interrelation between Pb content, ta and Ta exists. The presence of Pb is necessary to stabilize the high-Tc phase but its content depends on the annealing conditions.展开更多
We deal with the development of a solidification benchmark experiment in order to investigate the structure formation as well as solute macro-mesosegregation,by means of a well-controlled solidification experiment.The...We deal with the development of a solidification benchmark experiment in order to investigate the structure formation as well as solute macro-mesosegregation,by means of a well-controlled solidification experiment.The experiment consists in solidifying a rectangular ingot of Sn-3wt.%Pb alloy,by using two lateral heat exchangers which allow extraction of the heat flux from one or two vertical sides of the sample.The domain is a quasi two dimensional parallepipedic ingot(100×60×10)mm.The temperature difference AT between the two lateral sides is 40 K and the cooling rate CR=0.03 K/s.The instrumentation consists in recording the instantaneous temperature maps by means of an array of 50 thermocouples in order to provide the time evolution of the isotherms.After each experiment the patterns of the segregations have been obtained by X-ray radiograph and confirmed by eutectic fraction measurements.The local solute distribution determined by means of induction coupled plasma analysis is provided.The originality of the present study is to examine the effect of the forced convection driven by a travelling magnetic field(TMF)induced by a linear inductor located on the bottom part of the sample.A periodically reversed stirring with a modulation frequency equal to 0.5 Hz stirring have been investigated.This study allows us to evaluate the evolution due to the forced convection induced by a TMF field,as well as its influence on the initial conditions,the solidification macrostructure and the segregation behavior.Measurements of the velocity field by ultrasonic Doppler velocimetry(UDV)method in a Ga-In-Sn pool were performed and transposed to the tin-lead alloy case before solidification.Post-mortem patterns of the macromesosegregations have been obtained by X-ray radiography.The results show the transport effects of the flow on both the maerosegregations and the channel formation.The reversal of the TMF produces a decrease of the level of mesosegregations,namely channel formation.展开更多
文摘Three logarithmic linear equations between D_(Me)^(V/L) and [m_(NaCl)], and the relationship of D_(Me)^(V/L) versus F/Cl or K/Na mole ratios have been established by the experiments of the partitioning of Pb and Zn between granitic silicate melt and aqueous fluid. These results have been used to quantitatively study some essential problems, such as the possibility and degree of Pb-Zn mineralization in the system of granitic magma and hydrothermal fluid, and the influence of the relative contents of alkali and volatiles on the Pb-Zn mineralization in the same system. Some new points have been put forward in this paper.
文摘Actually recent investigation in developing semiconducting-superconducting composites based in CdS and Bi-based superconductors has attracted interest in processing thin superconducting films. In this work are reported Bi-Pb-Sr-Ca-Cu-O (BPSCCO) thin films grown on MgO substrates by spray pyrolysis technique from a solution containing Bi(NO3)3, Pb(NO3)2, Sr(NO3)2, Ca(NO3)2 and Cu(NO3)2, with a subsequent solid state reaction for growing the Bi-based superconducting phases. Annealed films were characterized by X-ray diffraction, atomic absorption spectroscopy and resistance measurements. Interdependence between Pb content, annealing time and temperature, in the formation of superconducting phases was studied applying a fractional factorial design 3III4-2. Interrelation between Pb content, ta and Ta exists. The presence of Pb is necessary to stabilize the high-Tc phase but its content depends on the annealing conditions.
基金Item Sponsored by European Space Agency through the CETSOL project (ESA-MAP AO-99-117) as well as the SMACS ANR project
文摘We deal with the development of a solidification benchmark experiment in order to investigate the structure formation as well as solute macro-mesosegregation,by means of a well-controlled solidification experiment.The experiment consists in solidifying a rectangular ingot of Sn-3wt.%Pb alloy,by using two lateral heat exchangers which allow extraction of the heat flux from one or two vertical sides of the sample.The domain is a quasi two dimensional parallepipedic ingot(100×60×10)mm.The temperature difference AT between the two lateral sides is 40 K and the cooling rate CR=0.03 K/s.The instrumentation consists in recording the instantaneous temperature maps by means of an array of 50 thermocouples in order to provide the time evolution of the isotherms.After each experiment the patterns of the segregations have been obtained by X-ray radiograph and confirmed by eutectic fraction measurements.The local solute distribution determined by means of induction coupled plasma analysis is provided.The originality of the present study is to examine the effect of the forced convection driven by a travelling magnetic field(TMF)induced by a linear inductor located on the bottom part of the sample.A periodically reversed stirring with a modulation frequency equal to 0.5 Hz stirring have been investigated.This study allows us to evaluate the evolution due to the forced convection induced by a TMF field,as well as its influence on the initial conditions,the solidification macrostructure and the segregation behavior.Measurements of the velocity field by ultrasonic Doppler velocimetry(UDV)method in a Ga-In-Sn pool were performed and transposed to the tin-lead alloy case before solidification.Post-mortem patterns of the macromesosegregations have been obtained by X-ray radiography.The results show the transport effects of the flow on both the maerosegregations and the channel formation.The reversal of the TMF produces a decrease of the level of mesosegregations,namely channel formation.
