This article discusses and analyzes the law of nitrogen increase in liquid steel and the main factors affect-ing the nitrogen increasing of molten steel,through the way of adding nitrogen to molten steel by bottom blo...This article discusses and analyzes the law of nitrogen increase in liquid steel and the main factors affect-ing the nitrogen increasing of molten steel,through the way of adding nitrogen to molten steel by bottom blowing nitrogen gas in LF refining process.It is considered that the main factors affecting the nitrogen increasing instability of molten steel are the initial temperature of LF refining,nitrogen relative element,surface active elements[O]and[S]of steel liquid,and bottom blowing rate of ladle.The large-scale production practice shows that T[O]not more than 50×10-6 and[S]is not more than 0.020 in LF refining at the initial temperature of not less than 1570.The liquid steel nitrogen enrichment test is carried out by ladle bottom blowing nitrogen gas after 20 min of refining,the flow rate is set as(6.0~7.0)NL/min per ton,and it is turned to 2 NL/min at 6 min before the end of refining,the nitrogen increasing rate of liquid steel is basically stable at(5~6)×10-6 per minute.展开更多
The layer structure of low-carbon steel containing RE by high-temperature (T>1200 ℃) carburizing of liquid cast-iron was studied and the diffusion activation energy of carbon was calculated by metallographic micr...The layer structure of low-carbon steel containing RE by high-temperature (T>1200 ℃) carburizing of liquid cast-iron was studied and the diffusion activation energy of carbon was calculated by metallographic microscpe, chemical analysis etc. The result shows that the technology of carburizing in liquid cast-iron can expedite caburization distinctly and changes the carburizing layer structure. The carburizing rate is 60～80 times of that of the traditional technology, and there is about 43% decrease in the activation energy compared with gas-carburization. In outer structure layer, cementite is formed simultaneously both on the crystal boundary reticularly and inside the crystal grains stripedly. In inner carburizing layer, there is undissolved blocky ferrite in reticular cementite. Besides, rare earth element can expedite carburization process.展开更多
In this paper, the carburizing kinetics of low-carbon steel at high-temperature and short-term in liquid cast-iron were studied by metallographic microscope, chemical analysis and so on, and the microstructure of carb...In this paper, the carburizing kinetics of low-carbon steel at high-temperature and short-term in liquid cast-iron were studied by metallographic microscope, chemical analysis and so on, and the microstructure of carburized layer was also analyzed. The results show that the carburizing rate of low-carbon steel at high-temperature and short-term is so fast, and the microstructure of carburized layer possess higher carbon content, and cementite, pearlite and ferrite exist in carburized layer structure simultaneously. Besides, the kinetic equations of permeating layer forming have been presented, and the carburizing mechanism was preliminary discussed also.展开更多
Metallic sodium(Na)is believed to be a promising anode material for sodium-ion batteries(SIBs)due to its low electrochemical potential,high theoretical specific capacity,superior electrical conductivity,and so on.Howe...Metallic sodium(Na)is believed to be a promising anode material for sodium-ion batteries(SIBs)due to its low electrochemical potential,high theoretical specific capacity,superior electrical conductivity,and so on.However,issues such as high chemical activity,the growth of Na dendrites,large volume change,and unstable interface impede its practical application.We design a cheap iron(Fe)-based substrate decorated by a thin liquid metal Ga layer for stable and dendrite-free Na metal anodes in low-cost carbonate electrolytes.The inherent mechanism of Ga-based liquid metal in inhibiting the growth of Na dendrites was revealed for the first time.Liquid metal Ga with sodiophilic property can act as nucleation seeds to decrease the nucleation barrier and induce homogeneous Na+flux,resulting in uniform and dendrite-free Na deposition.Full cells with Na_(3)V_(2)(PO_(4))_(3) cathode were also assembled to verify the practical application ability of the modified Na metal anode.Under the regulation of the liquid metal layer,the Coulombic efficiency,cycling life,and capacity of batteries are obviously enhanced.The strategy proposed here cannot only reduce the cost of batteries but also improve their electrochemical and safety performance.展开更多
文摘This article discusses and analyzes the law of nitrogen increase in liquid steel and the main factors affect-ing the nitrogen increasing of molten steel,through the way of adding nitrogen to molten steel by bottom blowing nitrogen gas in LF refining process.It is considered that the main factors affecting the nitrogen increasing instability of molten steel are the initial temperature of LF refining,nitrogen relative element,surface active elements[O]and[S]of steel liquid,and bottom blowing rate of ladle.The large-scale production practice shows that T[O]not more than 50×10-6 and[S]is not more than 0.020 in LF refining at the initial temperature of not less than 1570.The liquid steel nitrogen enrichment test is carried out by ladle bottom blowing nitrogen gas after 20 min of refining,the flow rate is set as(6.0~7.0)NL/min per ton,and it is turned to 2 NL/min at 6 min before the end of refining,the nitrogen increasing rate of liquid steel is basically stable at(5~6)×10-6 per minute.
文摘The layer structure of low-carbon steel containing RE by high-temperature (T>1200 ℃) carburizing of liquid cast-iron was studied and the diffusion activation energy of carbon was calculated by metallographic microscpe, chemical analysis etc. The result shows that the technology of carburizing in liquid cast-iron can expedite caburization distinctly and changes the carburizing layer structure. The carburizing rate is 60～80 times of that of the traditional technology, and there is about 43% decrease in the activation energy compared with gas-carburization. In outer structure layer, cementite is formed simultaneously both on the crystal boundary reticularly and inside the crystal grains stripedly. In inner carburizing layer, there is undissolved blocky ferrite in reticular cementite. Besides, rare earth element can expedite carburization process.
文摘In this paper, the carburizing kinetics of low-carbon steel at high-temperature and short-term in liquid cast-iron were studied by metallographic microscope, chemical analysis and so on, and the microstructure of carburized layer was also analyzed. The results show that the carburizing rate of low-carbon steel at high-temperature and short-term is so fast, and the microstructure of carburized layer possess higher carbon content, and cementite, pearlite and ferrite exist in carburized layer structure simultaneously. Besides, the kinetic equations of permeating layer forming have been presented, and the carburizing mechanism was preliminary discussed also.
基金the the National Natural Science Foundation of China(No.5197219862133007)+2 种基金Taishan Scholars Program of Shandong Province(Nos.tsqn201812002,ts20190908)the Natural Science Foundation of Shandong Province(No.ZR2020JQ19)the Project of the Taishan Scholar(No.ts201511004)。
文摘Metallic sodium(Na)is believed to be a promising anode material for sodium-ion batteries(SIBs)due to its low electrochemical potential,high theoretical specific capacity,superior electrical conductivity,and so on.However,issues such as high chemical activity,the growth of Na dendrites,large volume change,and unstable interface impede its practical application.We design a cheap iron(Fe)-based substrate decorated by a thin liquid metal Ga layer for stable and dendrite-free Na metal anodes in low-cost carbonate electrolytes.The inherent mechanism of Ga-based liquid metal in inhibiting the growth of Na dendrites was revealed for the first time.Liquid metal Ga with sodiophilic property can act as nucleation seeds to decrease the nucleation barrier and induce homogeneous Na+flux,resulting in uniform and dendrite-free Na deposition.Full cells with Na_(3)V_(2)(PO_(4))_(3) cathode were also assembled to verify the practical application ability of the modified Na metal anode.Under the regulation of the liquid metal layer,the Coulombic efficiency,cycling life,and capacity of batteries are obviously enhanced.The strategy proposed here cannot only reduce the cost of batteries but also improve their electrochemical and safety performance.
