The viscose flow and microstructure formation of Fe-Cu peritectic alloy melts are investigated by analyzing the velocity and temperature fields during rapid solidifi-cation,which is verified by rapid quenching experim...The viscose flow and microstructure formation of Fe-Cu peritectic alloy melts are investigated by analyzing the velocity and temperature fields during rapid solidifi-cation,which is verified by rapid quenching experiments.It is found that a large temperature gradient exists along the vertical direction of melt puddle,whereas there is no obvious temperature variation in the tangent direction of roller surface.After being sprayed from a nozzle,the alloy melt changes the magnitude and di-rection of its flow and velocity rapidly at a height of about 180 μm.The horizontal flow velocity increases rapidly,but the vertical flow velocity decreases sharply.A thermal boundary layer with 160-300 μm in height and a momentum boundary layer with 160-240 μm in thickness are formed at the bottom of melt puddle,and the Reynolds number Re is in the range of 870 to 1070 in the boundary layer.With the increase of Re number,the cooling rate increases linearly and the thickness of thermal boundary layer increases monotonically.The thickness of momentum boundary layer decreases slowly at first,then rises slightly and decreases sharply.If Re < 1024,the liquid flow has remarkable effects on the microstructure formation due to dominant momentum transfer.The separated liquid phase is likely to form a fiber-like microstructure.If Re>1024,the heat transfer becomes dominating and the liquid phase flow is suppressed,which results in the formation of fine and uniform equiaxed microstructures.展开更多
The phase behavior of a well-defined poly(methyl methacrylate)- b- polystyrene block copolymer was studied by transmission electron microscope. The results show that a microphase transition may have occurred in the co...The phase behavior of a well-defined poly(methyl methacrylate)- b- polystyrene block copolymer was studied by transmission electron microscope. The results show that a microphase transition may have occurred in the copolymer film. A kind of lamellae and an ordered bicontinuous double-diamond morphology are observed clearly. The lamellar morphology reveals a larger period of about 400 nm.展开更多
采用支撑液膜技术建立了进料相、膜相、反萃取相三相体系,实现了对洁霉素的分离提纯。该体系采用了洁霉素+异构烷烃(Isopar L)+HCl的反应体系,验证了进料浓度(Cbf)、进料相溶液pH、反萃取相溶液pH、萃取剂组成等因素对分配系数(D)的影...采用支撑液膜技术建立了进料相、膜相、反萃取相三相体系,实现了对洁霉素的分离提纯。该体系采用了洁霉素+异构烷烃(Isopar L)+HCl的反应体系,验证了进料浓度(Cbf)、进料相溶液pH、反萃取相溶液pH、萃取剂组成等因素对分配系数(D)的影响。同时,优化了膜组件实现萃取实验的操作条件,根据传质过程建立了数学模型。结果显示:当洁霉素Cbf为11.9 mmol/L、Isopar L体积分数(VF)为80%、进料相pH为10.1、反萃取相pH为1.2时,D最大为2.34。确定了膜组件操作条件为:管程流量Vf=520 m L/min,壳程流量Vs=500 m L/min。根据所建的数学模型分析了各部分传质阻力,其中管程传质阻力为6.7×10~5s/m,壳程传质阻力为3.7×10~5s/m,跨膜传质阻力为2.7×10~6s/m,跨膜传质阻力起主要作用。展开更多
Phase separations have been studied for graded-indium content In_xGa_（1-x）N/GaN multiple quantum wells（MQWs） with different indium contents by means of photoluminescence（PL）,cathodeluminescence（CL） and time-re...Phase separations have been studied for graded-indium content In_xGa_（1-x）N/GaN multiple quantum wells（MQWs） with different indium contents by means of photoluminescence（PL）,cathodeluminescence（CL） and time-resolved PL（TRPL） techniques.Besides the main emission peaks,all samples show another 2 peaks at the high and low energy parts of the main peaks in PL when excited at 10 K.CL images show a clear contrast for 3 samples,which indicates an increasing phase separation with increasing indium content.TRPL spectra at 15 K of the main emissions show an increasing delay of rising time with indium content,which means a carrier transferring from low indium content structures to high indium content structures.展开更多
基金the National Natural Science Foundation of China(Grant Nos.50121101 and 50395105)
文摘The viscose flow and microstructure formation of Fe-Cu peritectic alloy melts are investigated by analyzing the velocity and temperature fields during rapid solidifi-cation,which is verified by rapid quenching experiments.It is found that a large temperature gradient exists along the vertical direction of melt puddle,whereas there is no obvious temperature variation in the tangent direction of roller surface.After being sprayed from a nozzle,the alloy melt changes the magnitude and di-rection of its flow and velocity rapidly at a height of about 180 μm.The horizontal flow velocity increases rapidly,but the vertical flow velocity decreases sharply.A thermal boundary layer with 160-300 μm in height and a momentum boundary layer with 160-240 μm in thickness are formed at the bottom of melt puddle,and the Reynolds number Re is in the range of 870 to 1070 in the boundary layer.With the increase of Re number,the cooling rate increases linearly and the thickness of thermal boundary layer increases monotonically.The thickness of momentum boundary layer decreases slowly at first,then rises slightly and decreases sharply.If Re < 1024,the liquid flow has remarkable effects on the microstructure formation due to dominant momentum transfer.The separated liquid phase is likely to form a fiber-like microstructure.If Re>1024,the heat transfer becomes dominating and the liquid phase flow is suppressed,which results in the formation of fine and uniform equiaxed microstructures.
文摘The phase behavior of a well-defined poly(methyl methacrylate)- b- polystyrene block copolymer was studied by transmission electron microscope. The results show that a microphase transition may have occurred in the copolymer film. A kind of lamellae and an ordered bicontinuous double-diamond morphology are observed clearly. The lamellar morphology reveals a larger period of about 400 nm.
文摘采用支撑液膜技术建立了进料相、膜相、反萃取相三相体系,实现了对洁霉素的分离提纯。该体系采用了洁霉素+异构烷烃(Isopar L)+HCl的反应体系,验证了进料浓度(Cbf)、进料相溶液pH、反萃取相溶液pH、萃取剂组成等因素对分配系数(D)的影响。同时,优化了膜组件实现萃取实验的操作条件,根据传质过程建立了数学模型。结果显示:当洁霉素Cbf为11.9 mmol/L、Isopar L体积分数(VF)为80%、进料相pH为10.1、反萃取相pH为1.2时,D最大为2.34。确定了膜组件操作条件为:管程流量Vf=520 m L/min,壳程流量Vs=500 m L/min。根据所建的数学模型分析了各部分传质阻力,其中管程传质阻力为6.7×10~5s/m,壳程传质阻力为3.7×10~5s/m,跨膜传质阻力为2.7×10~6s/m,跨膜传质阻力起主要作用。
基金Project supported by the National Natural Science Foundation of China(No.11174241)the Natural Science Foundation of Shandong Province,China(No.2009VRA06063)the Natural Science Foundation for Distinguished Young Scholars of Shandong Province, China(No.2008JQB01028)
文摘Phase separations have been studied for graded-indium content In_xGa_（1-x）N/GaN multiple quantum wells（MQWs） with different indium contents by means of photoluminescence（PL）,cathodeluminescence（CL） and time-resolved PL（TRPL） techniques.Besides the main emission peaks,all samples show another 2 peaks at the high and low energy parts of the main peaks in PL when excited at 10 K.CL images show a clear contrast for 3 samples,which indicates an increasing phase separation with increasing indium content.TRPL spectra at 15 K of the main emissions show an increasing delay of rising time with indium content,which means a carrier transferring from low indium content structures to high indium content structures.
