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
This work is devoted to study the behaviour of an inductively coupled plasma torch using argon,hydrogen and oxygen at atmospheric pressure.Thermal plasmas are generally used to form highly reactive species and to tran...This work is devoted to study the behaviour of an inductively coupled plasma torch using argon,hydrogen and oxygen at atmospheric pressure.Thermal plasmas are generally used to form highly reactive species and to transfer enthalpy.Precise characterisation of the plasma behaviour is thus relevant to evaluate chemical and thermal effects of the plasma.For equivalent configurations in terms of torch geometry and gas flows,a transition between two different coupling modes is identified affecting atomic species distribution and energy transmitted to a copper target.These two modes are affected by total electrical power input and oxygen and hydrogen flow rates,showing up hysteresis behaviour. Electrical current and frequency progress are analysed to highlight the transition between the two coupling modes. Optical spectroscopy is used to measure temperature profiles and radial atomic oxygen concentration profiles for different coupling modes.We observe that-depending on the coupling mode-temperature profile,atomic species distribution as well as the power transmission to a copper target are affected.展开更多
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.
文摘This work is devoted to study the behaviour of an inductively coupled plasma torch using argon,hydrogen and oxygen at atmospheric pressure.Thermal plasmas are generally used to form highly reactive species and to transfer enthalpy.Precise characterisation of the plasma behaviour is thus relevant to evaluate chemical and thermal effects of the plasma.For equivalent configurations in terms of torch geometry and gas flows,a transition between two different coupling modes is identified affecting atomic species distribution and energy transmitted to a copper target.These two modes are affected by total electrical power input and oxygen and hydrogen flow rates,showing up hysteresis behaviour. Electrical current and frequency progress are analysed to highlight the transition between the two coupling modes. Optical spectroscopy is used to measure temperature profiles and radial atomic oxygen concentration profiles for different coupling modes.We observe that-depending on the coupling mode-temperature profile,atomic species distribution as well as the power transmission to a copper target are affected.
