Bursting of gas bubbles on the free surface of liquid iron produces iron droplets that are ejected into the surrounding atmosphere. The influence of the freeboard pressure on gas bubble bursting was investigated by co...Bursting of gas bubbles on the free surface of liquid iron produces iron droplets that are ejected into the surrounding atmosphere. The influence of the freeboard pressure on gas bubble bursting was investigated by collecting and measuring the formed droplets in water and in liquid iron systems. In water model, it was found that gas bubbles expanded markedly during the floating up when the freeboard was evacuated but the influence of the freeboard pressure on the mass of ejection is not significant when the freeboard pressure varied from 0.01 to 0.1 MPa. Besides, in steel melt, the mass of ejection was increased by 2--3 times when the pressure was reduced from atmospheric pressure to 66.5 Pa.展开更多
With pretty high surface tension, the room temperature liquid metal may inherit with unexpected be- haviors that conventional fluids could not own. Here, we disclosed the coalescence and ejection phenomena of liquid m...With pretty high surface tension, the room temperature liquid metal may inherit with unexpected be- haviors that conventional fluids could not own. Here, we disclosed the coalescence and ejection phenomena of liquid metal droplets via high-speed camera. It was experimen- tally found that, when gently contacting （rather than col- liding） two metal droplets with identical size together in NaOH solution, oscillating coalescence would happen which runs just like a spring after the interface ruptures and forms capillary waves. For two metal droplets with evidently different diameters, the coalescence induces rather unusual ejection phenomena. The large droplet would swallow part of the small one and then eject another much smaller droplet. Such phenomenon provides a direct evidence for the existence of electrical double layer on metal droplets. The dynamics fluid impacting behaviors were quantified through processing images from the recorded movies, and the basic differences between the liquid metal droplets and that of water droplets were clar- ified. Theoretical mechanisms related to the events were preliminarily interpreted. The present finding refreshes the basic understanding of the liquid metal droplets, which also suggests potential values of applying such fundamental effects to characterize viscosity, surface tension, electrical double layer of the metal fluids and droplet formations.展开更多
The Knudsen effusion cell is often used to grow high-quality Cu(In,Ga)Se_(2)(CIGS)thin film in coevaporation processes.However,the traditional single-heating Knudsen effusion cell cannot deliver complete metal selenid...The Knudsen effusion cell is often used to grow high-quality Cu(In,Ga)Se_(2)(CIGS)thin film in coevaporation processes.However,the traditional single-heating Knudsen effusion cell cannot deliver complete metal selenides during the whole deposition process,particularly for a low-temperature deposition process,which is probably due to the condensation and droplet ejection at the nozzle of the crucible.In this study,thermodynamics analysis is conducted to decipher the reason for this phenomenon.Furthermore,a new single-heating Knudsen effusion is proposed to solve this difficult problem,which leads to an improvement in the quality of CIGS film and a relative increase in conversion efficiency of 29%at a growth rate of about 230 nmmin1,compared with the traditional efficiency in a lowtemperature rapid-deposition process.展开更多
文摘Bursting of gas bubbles on the free surface of liquid iron produces iron droplets that are ejected into the surrounding atmosphere. The influence of the freeboard pressure on gas bubble bursting was investigated by collecting and measuring the formed droplets in water and in liquid iron systems. In water model, it was found that gas bubbles expanded markedly during the floating up when the freeboard was evacuated but the influence of the freeboard pressure on the mass of ejection is not significant when the freeboard pressure varied from 0.01 to 0.1 MPa. Besides, in steel melt, the mass of ejection was increased by 2--3 times when the pressure was reduced from atmospheric pressure to 66.5 Pa.
基金This work was partially supported by the Re- search Funding of the Chinese Academy of Sciences （KGZD-EW-T04-4） and the National Natural Science Foundation of China （81071225）.
文摘With pretty high surface tension, the room temperature liquid metal may inherit with unexpected be- haviors that conventional fluids could not own. Here, we disclosed the coalescence and ejection phenomena of liquid metal droplets via high-speed camera. It was experimen- tally found that, when gently contacting （rather than col- liding） two metal droplets with identical size together in NaOH solution, oscillating coalescence would happen which runs just like a spring after the interface ruptures and forms capillary waves. For two metal droplets with evidently different diameters, the coalescence induces rather unusual ejection phenomena. The large droplet would swallow part of the small one and then eject another much smaller droplet. Such phenomenon provides a direct evidence for the existence of electrical double layer on metal droplets. The dynamics fluid impacting behaviors were quantified through processing images from the recorded movies, and the basic differences between the liquid metal droplets and that of water droplets were clar- ified. Theoretical mechanisms related to the events were preliminarily interpreted. The present finding refreshes the basic understanding of the liquid metal droplets, which also suggests potential values of applying such fundamental effects to characterize viscosity, surface tension, electrical double layer of the metal fluids and droplet formations.
基金The work was supported by the National Key R&D Program of China(2018YFB1500200)the National Natural Science Foundation of China(61774089 and 61974076)the Natural Science Foundation of Tianjin(18JCZDJC31200).
文摘The Knudsen effusion cell is often used to grow high-quality Cu(In,Ga)Se_(2)(CIGS)thin film in coevaporation processes.However,the traditional single-heating Knudsen effusion cell cannot deliver complete metal selenides during the whole deposition process,particularly for a low-temperature deposition process,which is probably due to the condensation and droplet ejection at the nozzle of the crucible.In this study,thermodynamics analysis is conducted to decipher the reason for this phenomenon.Furthermore,a new single-heating Knudsen effusion is proposed to solve this difficult problem,which leads to an improvement in the quality of CIGS film and a relative increase in conversion efficiency of 29%at a growth rate of about 230 nmmin1,compared with the traditional efficiency in a lowtemperature rapid-deposition process.
