Liquid-metal cooling(LMC)process can offer refinement of microstructure and reduce defects due to the increased cooling rate from enhanced heat extraction,and thus an understanding of solidification behavior in nickel...Liquid-metal cooling(LMC)process can offer refinement of microstructure and reduce defects due to the increased cooling rate from enhanced heat extraction,and thus an understanding of solidification behavior in nickel-based superalloy casting during LMC process is essential for improving mechanical performance of single crystal(SC)castings.In this effort,an integrated heat transfer model coupling meso grain structure and micro dendrite is developed to predict the temperature distribution and microstructure evolution in LMC process.An interpolation algorithm is used to deal with the macro-micro grids coupling issues.The algorithm of cells capture is also modified,and a deterministic cellular automaton(DCA)model is proposed to describe neighborhood cell tracking.In addition,solute distribution is also considered to describe the dendrite growth.Temperature measuring,EBSD,OM and SEM experiments are implemented to verify the proposed model,and the experiment results agree well with the simulation results.Several simulations are performed with a range of withdrawal rates,and the results indicate that 12 mm·min^(-1)is suitable for LMC process in this work,which can result in a fairly narrow and flat mushy zone and correspondingly exhibited fairly straight grains.The mushy zone length is about 4.8 mm in the steady state and the average deviation angle of grains is about 13.9°at the height 90 mm from the casting base under 12 mm·min^(-1)withdrawal process.The competitive phenomenon of dendrites at different withdrawal rates is also observed,which has a great relevant to the temperature fluctuation.展开更多
It has long been a dream in the electronics industry to be able to write out electronics directly, as simply as printing a picture onto paper with an offi ce printer. The fi rstever prototype of a liquid-metal printer...It has long been a dream in the electronics industry to be able to write out electronics directly, as simply as printing a picture onto paper with an offi ce printer. The fi rstever prototype of a liquid-metal printer has been invented and demonstrated by our lab, bringing this goal a key step closer. As part of a continuous endeavor, this work is dedicated to significantly extending such technology to the consumer level by making a very practical desktop liquid-metal printer for society in the near future. Through the industrial design and technical optimization of a series of key technical issues such as working reliability, printing resolution, automatic control, human-machine interface design, software, hardware, and integration between software and hardware, a high-quality personal desktop liquid-metal printer that is ready for mass production in industry was fabricated. Its basic features and important technical mechanisms are explained in this paper, along with demonstrations of several possible consumer end-uses for making functional devices such as li ght-emitting diode(LED) displays. This liquid-metal printer is an automatic, easyto-use, and low-cost personal electronics manufacturing tool with many possible applications. This paper discusses important roles that the new machine may play for a group of emerging needs. The prospective future of this cuttingedge technology is outlined, along with a comparative interpretation of several historical printing methods. This desktop liquid-metal printer is expected to become a basic electronics manufacturing tool for a wide variety of emerging practices in the academic realm, in industry, and in education as well as for individual end-users in the near future.展开更多
New design solutions have been proposed for a BRS-GPG type reactor circuit, which are different from transport and stationary low and medium-powered reactor installations cooled with heavy liquid-metal coolants, and w...New design solutions have been proposed for a BRS-GPG type reactor circuit, which are different from transport and stationary low and medium-powered reactor installations cooled with heavy liquid-metal coolants, and which correspond to the evolutionary development of such installations. While developing these solutions, the available experience in creating and operating So</span><span>viet pilot and commercial power plants cooled with lead-bismuth coolants</span><span> was used, including investigations, primarily experimental ones, carried out by team of authors in justification of a capacity range (50</span></span><span> </span><span>-</span><span> </span><span>250 MW) of low and medium-powered reactor plants with horizontal steam generators (BRS-</span><span> </span><span>GPG) proposed and elaborated at the NNSTU.展开更多
The study investigated the oxidation behavior of T91 steel modified with Al(T91-Al)and Si(T91-Si)in lead-bismuth eutectic(LBE)at 450℃under oxygen-saturated conditions(10^(−7)-10^(−8)wt.%)and oxygen-controlled conditi...The study investigated the oxidation behavior of T91 steel modified with Al(T91-Al)and Si(T91-Si)in lead-bismuth eutectic(LBE)at 450℃under oxygen-saturated conditions(10^(−7)-10^(−8)wt.%)and oxygen-controlled conditions(3.2×10^(−4)wt.%).Advanced characterization techniques were employed to under-stand the thermodynamic and kinetic mechanisms of enhanced oxidation properties of the modified T91 steel.The results indicate that the oxidation resistance of the materials follows this order:T91<T91-Al<T91-Si.Noteworthy,the oxidation resistance of T91-Si material exhibited minimal correlation with dissolved oxygen.Under oxygen-controlled conditions,the oxide film of T91 and T91-Al was attacked and broken by LBE,with the former eventually peeling off.In contrast,both materials showed significant ox-ide film thickening,except T91-Si under oxygen-saturated conditions.The addition of Al improved the quality of the inner oxide film on T91-Al by generating Al_(2)O_(3),thereby slowing down the diffusion of Fe from the matrix and enhancing oxidation resistance.Conversely,Si actively participated in the oxidation process of T91-Si,slowing down the diffusion of Fe,and facilitating the diffusion of Cr,thereby strength-ening the oxide film protection.Consequently,the oxide thickness of T91-Si material was only 24%of T91 and 35%of T91-Al under saturated oxygen conditions.展开更多
基金supported by the National Natural Science Foundation of China(No.51904276)Science and Technology Development Program of Henan Province(No.192102210013,202102210080)National Science and Technology Major Project(No.2017-VII-0008-0101)。
文摘Liquid-metal cooling(LMC)process can offer refinement of microstructure and reduce defects due to the increased cooling rate from enhanced heat extraction,and thus an understanding of solidification behavior in nickel-based superalloy casting during LMC process is essential for improving mechanical performance of single crystal(SC)castings.In this effort,an integrated heat transfer model coupling meso grain structure and micro dendrite is developed to predict the temperature distribution and microstructure evolution in LMC process.An interpolation algorithm is used to deal with the macro-micro grids coupling issues.The algorithm of cells capture is also modified,and a deterministic cellular automaton(DCA)model is proposed to describe neighborhood cell tracking.In addition,solute distribution is also considered to describe the dendrite growth.Temperature measuring,EBSD,OM and SEM experiments are implemented to verify the proposed model,and the experiment results agree well with the simulation results.Several simulations are performed with a range of withdrawal rates,and the results indicate that 12 mm·min^(-1)is suitable for LMC process in this work,which can result in a fairly narrow and flat mushy zone and correspondingly exhibited fairly straight grains.The mushy zone length is about 4.8 mm in the steady state and the average deviation angle of grains is about 13.9°at the height 90 mm from the casting base under 12 mm·min^(-1)withdrawal process.The competitive phenomenon of dendrites at different withdrawal rates is also observed,which has a great relevant to the temperature fluctuation.
基金supported by the Research Funding of the Chinese Academy of Sciences (KGZD-EW-T04-4)
文摘It has long been a dream in the electronics industry to be able to write out electronics directly, as simply as printing a picture onto paper with an offi ce printer. The fi rstever prototype of a liquid-metal printer has been invented and demonstrated by our lab, bringing this goal a key step closer. As part of a continuous endeavor, this work is dedicated to significantly extending such technology to the consumer level by making a very practical desktop liquid-metal printer for society in the near future. Through the industrial design and technical optimization of a series of key technical issues such as working reliability, printing resolution, automatic control, human-machine interface design, software, hardware, and integration between software and hardware, a high-quality personal desktop liquid-metal printer that is ready for mass production in industry was fabricated. Its basic features and important technical mechanisms are explained in this paper, along with demonstrations of several possible consumer end-uses for making functional devices such as li ght-emitting diode(LED) displays. This liquid-metal printer is an automatic, easyto-use, and low-cost personal electronics manufacturing tool with many possible applications. This paper discusses important roles that the new machine may play for a group of emerging needs. The prospective future of this cuttingedge technology is outlined, along with a comparative interpretation of several historical printing methods. This desktop liquid-metal printer is expected to become a basic electronics manufacturing tool for a wide variety of emerging practices in the academic realm, in industry, and in education as well as for individual end-users in the near future.
文摘New design solutions have been proposed for a BRS-GPG type reactor circuit, which are different from transport and stationary low and medium-powered reactor installations cooled with heavy liquid-metal coolants, and which correspond to the evolutionary development of such installations. While developing these solutions, the available experience in creating and operating So</span><span>viet pilot and commercial power plants cooled with lead-bismuth coolants</span><span> was used, including investigations, primarily experimental ones, carried out by team of authors in justification of a capacity range (50</span></span><span> </span><span>-</span><span> </span><span>250 MW) of low and medium-powered reactor plants with horizontal steam generators (BRS-</span><span> </span><span>GPG) proposed and elaborated at the NNSTU.
基金financial support from the National Key R&D Program of China(No.2020YFA0405901)the National Natural Science Foundation of China(Nos.52375155 and 51875398).
文摘The study investigated the oxidation behavior of T91 steel modified with Al(T91-Al)and Si(T91-Si)in lead-bismuth eutectic(LBE)at 450℃under oxygen-saturated conditions(10^(−7)-10^(−8)wt.%)and oxygen-controlled conditions(3.2×10^(−4)wt.%).Advanced characterization techniques were employed to under-stand the thermodynamic and kinetic mechanisms of enhanced oxidation properties of the modified T91 steel.The results indicate that the oxidation resistance of the materials follows this order:T91<T91-Al<T91-Si.Noteworthy,the oxidation resistance of T91-Si material exhibited minimal correlation with dissolved oxygen.Under oxygen-controlled conditions,the oxide film of T91 and T91-Al was attacked and broken by LBE,with the former eventually peeling off.In contrast,both materials showed significant ox-ide film thickening,except T91-Si under oxygen-saturated conditions.The addition of Al improved the quality of the inner oxide film on T91-Al by generating Al_(2)O_(3),thereby slowing down the diffusion of Fe from the matrix and enhancing oxidation resistance.Conversely,Si actively participated in the oxidation process of T91-Si,slowing down the diffusion of Fe,and facilitating the diffusion of Cr,thereby strength-ening the oxide film protection.Consequently,the oxide thickness of T91-Si material was only 24%of T91 and 35%of T91-Al under saturated oxygen conditions.
