The effect of the initial(Al+Si)/MnO molar ratio and slag composition on MnO recovery from electroslag by remelting at 1773 K was investigated.High-purity aluminum metal and silicon were employed as the deoxidizers to...The effect of the initial(Al+Si)/MnO molar ratio and slag composition on MnO recovery from electroslag by remelting at 1773 K was investigated.High-purity aluminum metal and silicon were employed as the deoxidizers to effectively promote the recovery of manganese metal(MM).The reduction of MnO in slag,through the interaction between molten MM with a deoxidizer and the Na_(2)O-enriched electroslag melt,was assessed both thermodynamically and kinetically.The sulfur content of high-sulfur rejected electrolytic manganese metal(EMM)scrap decreased to 0.58%with high-temperature pretreatment.The mass ratio between slag and high-sulfur rejected EMM scrap is 2/3.When the Al_(2)O_(3)content in the initial slags decreased and the Na_(2)O content increased,the MnO reduction ratio increased.The residual MnO concentration of the slag reduced with increasing the Al–Si deoxidizer content.When the(Al+Si)/MnO molar ratio reached 0.83,the MnO concentration in the final slag was only 3%.A deoxidizer mainly containing aluminum and a small amount of Si could be added to recover MnO from the slag,resulting in the improvement in the cleanliness of final Mn metal.展开更多
This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two exp...This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two experimental shipbuilding steels after being subjected to high-heat input welding at 400 kJ·cm^(-1).The base metals (BMs) of both steels contained three types of precipitates Type Ⅰ:cubic (Ti,Nb)(C,N),Type Ⅱ:precipitate with cubic (Ti,Nb)(C,N) core and Nb-rich cap,and Type Ⅲ:ellipsoidal Nb-rich precipitate.In the BM of 60Al and 160Al steels,the number densities of the precipitates were 11.37×10^(5) and 13.88×10^(5) mm^(-2),respectively The 60Al and 160Al steel contained 38.12% and 6.39% Type Ⅲ precipitates,respectively.The difference in the content of Type Ⅲ precipitates in the 60Al steel reduced the pinning effect at the elevated temperature of the CGHAZ,which facilitated the growth of PAGs The average PAG sizes in the CGHAZ of the 60Al and 160Al steels were 189.73 and 174.7μm,respectively.In the 60Al steel,the low lattice mismatch among Cu_(2)S,TiN,and γ-Al_(2)O_(3)facilitated the precipitation of Cu_(2)S and TiN onto γ-Al_(2)O_(3)during welding,which decreased the number density of independently precipitated (Ti,Nb)(C,N) particles but increased that of γ-Al_(2)O_(3)–Ti N–Cu_(2)S particles.Thus abnormally large PAGs formed in the CGHAZ of the 60Al steel,and they reached a maximum size of 1 mm.These PAGs greatly reduced the microstructural homogeneity and consequently decreased the impact toughness from 134 (0.016wt%Al) to 54 J (0.006wt%Al)at-40℃.展开更多
Microstructures and inclusions in the Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of the inclusions were analyzed using a field emission scanning electron ...Microstructures and inclusions in the Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of the inclusions were analyzed using a field emission scanning electron microscope （FE-SEM） with energy dispersive X-ray spectrometry （EDS）. The kind and composition of the inclusions calculated from the thermodynamic database were in good agreement with the experimental results. There were two main kinds of inclusions formed in the Si-Mn-Ti deoxidized steels. One kind of inclusion was the manganese titanium oxide （Mn-Ti oxide）. Another kind of inclusion was the MnS inclusion with segregation points containing Ti and N. According to the thermodynamic calculation, those segregation points were TiN precipitates. The formation of intragranular ferrite （IGF） microstructures refined the grain size during the austenite-ferrite transformation. The mechanisms of IGF formation were discussed. Mn-Ti oxide inclusions with Mn-depleted zone （MDZ） were effective to be nucleation sites for IGF formation, because the MDZ increased the austenite-ferrite transformation temperature. TiN had the low misfit ratio with IGF, so the TiN precipitated on the MnS surface also promoted the formation of IGF because of decreasing interfacial energies.展开更多
The effects of different hot deformation amounts on the evolution of inclusion and microstructure in Ti-Zr deoxidized steel were studied by utilizing the Thermecmaster-Z hot simulation test machine,automatic scanning ...The effects of different hot deformation amounts on the evolution of inclusion and microstructure in Ti-Zr deoxidized steel were studied by utilizing the Thermecmaster-Z hot simulation test machine,automatic scanning electron microscope equipped with energy-dispersive spectrometer,and electron backscattered diffraction.The results indicated that hot deformation amount has no significant effect on the number density of oxide,but the MnS that precipitated on the Ti-Zr oxide surface undergoes extension and breakage,resulting in the changes in oxide aspect ratio.Moreover,the fracture of nitride mainly occurs in the sample with the second pass deformation amount of 42.9%and 71.4%,and the degree of fragmentation of nitride is more serious with the deformation amount increasing.During the hot compression,sulfide undergoes breakage and extension,and with the second pass deformation amount increasing,the breakage and extension of sulfide present a periodic change.Finally,with the increase in hot compression amount,the ferrite types in microstructure change from acicular ferrite and bainitic ferrite to polygonal ferrite,and the ferrite grain size is refined.When the total deformation amount increases from 30%to 80%,the ferrite grain sizes of grain boundary with the misorientation of 4°and 15°decrease from 4.14 and 5.67μm to 3.47 and 4.40μm,respectively.However,when the total deformation amount increases to 80%,the harmful ferrite/pearlite banded structure appears in the micro structure.Refining ferrite grain size and avoiding harmful microstructure are the key for the optimization of hot compression process.展开更多
To avoid coarse crystallization of glassy inclusions in Si–Mn deoxidized steel during hot rolling, the effect of MgO on the structure and crystallization behavior of CaO–SiO_(2)–Al_(2)O_(3) inclusions was investiga...To avoid coarse crystallization of glassy inclusions in Si–Mn deoxidized steel during hot rolling, the effect of MgO on the structure and crystallization behavior of CaO–SiO_(2)–Al_(2)O_(3) inclusions was investigated. The results showed that the crystallization temperature of the oxide melts decreased with increasing MgO content from 0 to 15.7 wt.%, which suggested that the addition of MgO would increase the temperature range of the crystalline transition. The increase in MgO content could decrease the crystallization activation energy of inclusions. With the increase in MgO content, the relative fractions of O_(Si)^(0) and O_(Si)^(1) structure units increased, and those of structure units O_(Si)^(2), O_(Si)^(3), and O_(Si)^(4) decreased, increasing the depolymerization degree of the silicate structure. The crystallization ratio of glassy inclusions in the steel crucible increased from 19.7% to 98.3% with increasing MgO content from 0 to 15.7 wt.%. The addition of MgO improved the crystallization ability of inclusions, because MgO provides free oxygen O_(2−) to destroy the bridging oxygens and form non-bridging oxygens O^(−), which depolymerizes silicate network structure and simplifies the [SiO_(4)]-tetrahedral structure. In addition, MgO would promote the precipitation of the Mg-containing phases with a high melting point. When the MgO content was increased above 12.1 wt.%, MgO·Al_(2)O_(3) and 2MgO·SiO_(2) crystalline phases would precipitate from the inclusions.展开更多
Because there are a lot of influences of alumina inclusions on the performance of rail steel,it is reasonable to adopt the deoxidization method with Al-free deoxidizer. According to the characteristics of Al-free deox...Because there are a lot of influences of alumina inclusions on the performance of rail steel,it is reasonable to adopt the deoxidization method with Al-free deoxidizer. According to the characteristics of Al-free deoxidization process,the control of aluminum content,the deoxidization with ladle furnace（LF） slag,the deoxidization process under vacuum by carbon,and the inclusions modification technology by calcium treatment were studied. All of them were applied to practical production. The results indicate that the adoption of Al-free deoxidization process leads to the total oxygen content in the steel below 20 ppm,which meets the requirement of clean rail steel.展开更多
Aiming at the nozzle blocking problem in rectangular bloom production, analyze the reason, and put forword to using non-aluminium producing process to solve this problem. By analysis the experiment data, that indicate...Aiming at the nozzle blocking problem in rectangular bloom production, analyze the reason, and put forword to using non-aluminium producing process to solve this problem. By analysis the experiment data, that indicate using non-aluminium process we can get good desulfurization and white slag, also get good castability and best quality. This process can fulfill the requirement of produce, it is reasonable and feasible.展开更多
Complex deoxidizer is an important supplementary material for steelmaking,which can not only absorb liquid steel inclusions and improve the quality of molten steel,but also enhance deoxidation,desulfurization, dephosp...Complex deoxidizer is an important supplementary material for steelmaking,which can not only absorb liquid steel inclusions and improve the quality of molten steel,but also enhance deoxidation,desulfurization, dephosphorization,to prevent the molten steel suction and reduce the molten steel temperature loss.Currently,the complex deoxidizer all contain a certain amount of metal aluminium.The metal aluminium can not be determined for the steel.The entire aluminium contents were regarded as the content of approximate metal aluminium,that often bring great economic losses.Because A1,0,price is cheaper than metal aluminite powder,suppliers added a certain amount of Al_2O_3 in complex deoxidizer,pretend to be the metal aluminium to reap huge profits.This paper put forward a kind of method for determining aluminum,which would reduce loss of the enterprise.Research and put forward an iron triehloride,which extracted from Al metal from complex deoxidizer.Meantime,using orthogonal design of the experiment has been optimized for working conditions.The RSD of the samples are I. 07%-1.94%,the recoveries of the experiment results are 97.0%-110.0%,which expressed the precision and accuracy of the experiment are good.The establishment of the iron triehloride as a extractor,which is rapid and accurate for determination of Al metal in complex deoxidizer.展开更多
Mn-Ti oxides in Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of inclusions were analyzed by using FE-SEM with EDS. Mn-Ti oxides were found to be effective s...Mn-Ti oxides in Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of inclusions were analyzed by using FE-SEM with EDS. Mn-Ti oxides were found to be effective sites to induce intragranular ferrite formation. The thermodynamic calculation was employed to interpret the critical condition for Mn-Ti oxide formation. Mn-Ti oxide formation was controlled not only by Mn and Ti content, but also by total oxygen content in steel. When the Mn and Ti contents were around 1.5% and 0. 005% --0.01%, respectively, Mn-Ti oxide could form as the total oxygen content was 0. 001%- 0. 002 %. The experimental results were in good agreement with thermodynamic calculation results. Also, MnS solubilit：（ was examined in Mn-Ti oxide inclusion system. With an increase of MnO content in Mn-Ti oxide, MnS solubility in the oxides increased. MnS precipitation benefited from high MnO content in Mn-Ti oxide.展开更多
The electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,t...The electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,the intrinsic complexity of this multi-step reaction severely constrains both the selectivity and efficiency of NO3RR.Copper-based electrocatalysts have been extensively investigated for NO_(3)RR but often suffer from nitrite(NO_(2)^(−))accumulation,which stems from insufficient NO_(3)^(−)adsorption strength.This limitation often leads to rapid catalyst deactivation,hindered hydrogenation pathways,and reduced overall efficiency.Herein,we report a one-step green chemical reduction method to synthesize PtCuSnCo quarternary alloy nanoparticles with homogeneously distributed elements.Under practical NO3−concentrations,the optimized catalyst exhibited an impressive Faradaic efficiency approaching 100%and an outstanding selectivity of 95.6±2.9%.Mechanistic insights uncovered that SnCo sites robustly facilitated NO_(3)^(−)adsorption,complemented by the proficiency of PtCu sites in NO3−reduction.The synergistic spatial neighborhood effect between SnCo and PtCu sites efficiently stabilizes NO_(3)^(−)deoxygenation and suppresses NO_(2)^(−)accumulation.This tandem architecture achieves a finely tuned balance between adsorption strength and deoxygenation kinetics,enabling highly selective and efficient NO3RR.Our findings emphasize the indispensable role of engineered multi-metallic catalysts in overcoming persistent challenges of NO3RR,paving the way for advanced NH3 synthesis and environmental remediation.展开更多
In recent years,studies focusing on the conversion of renewable lignin-derived oxygenates(LDOs)have emphasized their potential as alternatives to fossil-based products.However,LDOs,existing as complex aromatic mixture...In recent years,studies focusing on the conversion of renewable lignin-derived oxygenates(LDOs)have emphasized their potential as alternatives to fossil-based products.However,LDOs,existing as complex aromatic mixtures with diverse oxygen-containing functional groups,pose a challenge as they cannot be easily separated via distillation for direct utilization.A promising solution to this challenge lies in the efficient removal of oxygen-containing functional groups from LDOs through hydrodeoxygenation(HDO),aiming to yield biomass products with singular components.However,the high dissociation energy of the carbon-oxygen bond,coupled with its similarity to the hydrogenation energy of the benzene ring,creates a competition between deoxygenation and benzene ring hydrogenation.Considering hydrogen consumption and lignin properties,the preference is directed towards generating aromatic hydrocarbons rather than saturated components.Thus,the goal is to selectively remove oxygen-containing functional groups while preserving the benzene ring structure.Studies on LDOs conversion have indicated that the design of active components and optimization of reaction conditions play pivotal roles in achieving selective deoxygenation,but a summary of the correlation between these factors and the reaction mechanism is lacking.This review addresses this gap in knowledge by firstly summarizing the various reaction pathways for HDO of LDOs.It explores the impact of catalyst design strategies,including morphology modulation,elemental doping,and surface modification,on the adsorption-desorption dynamics between reactants and catalysts.Secondly,we delve into the application of advanced techniques such as spectroscopic techniques and computational modeling,aiding in uncovering the true active sites in HDO reactions and understanding the interaction of reactive reactants with catalyst surface-interfaces.Additionally,fundamental insights into selective deoxygenation obtained through these techniques are highlighted.Finally,we outline the challenges that lie ahead in the design of highly active and selective HDO catalysts.These challenges include the development of detection tools for reactive species with high activity at low concentrations,the study of reaction medium-catalyst interactions,and the development of theoretical models that more closely approximate real reaction situations.Addressing these challenges will pave the way for the development of efficient and selective HDO catalysts,thus advancing the field of renewable LDOs conversion.展开更多
A low-carbon,low-cost,and high-efficient method was reported for remarkably improving corrosion resistance of C–Mn structural steel by weak deoxidation.The results showed that,with the total oxygen content(wOT)increa...A low-carbon,low-cost,and high-efficient method was reported for remarkably improving corrosion resistance of C–Mn structural steel by weak deoxidation.The results showed that,with the total oxygen content(wOT)increasing in the tested steel from 41×10^(−6)to 195×10^(−6),both the degree of element segregation and the level of banded microstructure weakened,presenting the lower potential difference between pearlite(P)and ferrite(F),and then smaller galvanic corrosion driving force,and thus effectively improving general corrosion properties.In addition,with wOT growing up,the number and size of inclusions increased,and the shape also changed from long chain or small particle to large particle ball with typical mosaic structure,which could effectively inhibit the preferential dissolution of local component due to multiple complex interfaces,and correspondingly suppress the pitting susceptibility.However,the impact toughness at low temperature of the tested steel reduced with wOT increasing,and then,taking the mechanical properties and corrosion resistance all into account,160×10^(−6) was the optimal oxygen content within the present scope.展开更多
In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the...In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the steel liquid,affecting the cleanliness of the steel.With the increasing requirements for steel performance,reducing the oxygen content in the steel liquid and ensuring its high cleanliness is necessary.After more than a hundred years of development,the total oxygen content in steel has been reduced from approximately 100×10^(-6)to approximately 10×10^(-6),and it can be controlled below 5×10^(-6)in some steel grades.A relatively stable and mature deoxidation technology has been formed,but further reducing the oxygen content in steel is no longer significant for improving steel quality.Our research team developed a deoxidation technology for bearing steel by optimizing the entire conventional process.The technology combines silicon–manganese predeoxidation,ladle furnace diffusion deoxidation,and vacuum final deoxidation.We successfully conducted industrial experiments and produced interstitial-free steel with natural decarbonization predeoxidation.Non-aluminum deoxidation was found to control the oxygen content in bearing steel to between 4×10^(-6) and 8×10^(-6),altering the type of inclusions,eliminating large particle Ds-type inclusions,improving the flowability of the steel liquid,and deriving a higher fatigue life.The natural decarbonization predeoxidation of interstitial-free steel reduced aluminum consumption and production costs and significantly improved the quality of cast billets.展开更多
The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi 2 furnace at 1 873 K. The total oxygen contents of molten steel, the distribution, siz...The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi 2 furnace at 1 873 K. The total oxygen contents of molten steel, the distribution, size and morphology of deoxidation products in the steel were surveyed. The metamorphic mechanism for deoxidation products of alloy bearing barium was also discussed. The results show that applying alloy bearing barium to the pipe steel, very low total oxygen contents can be obtained, and deoxidation products, which easily float up from molten steel, can be changed into globular shape and uniformly distributed in steel. The equilibrium time of total oxygen is about 25 min, and the terminal total oxygen contents range from 0 002 0 % to 0 002 2 % after treating with SiCa wire. The best deoxidizers are SiAlBaCa and SiAlBaCaSr.展开更多
The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi2 furnace at 1 873 K.The total oxygen contents of molten steel,the distribution,size and...The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi2 furnace at 1 873 K.The total oxygen contents of molten steel,the distribution,size and morphology of deoxidation products in the steel were surveyed.The metamorphic mechanism for deoxidation products of alloy bearing barium was also discussed.The results show that applying alloy bearing barium to the pipe steel,very low total oxygen contents can be obtained,and deoxidation products,which easily float up from molten steel,can be changed into globular shape and uniformly distributed in steel.The equilibrium time of total oxygen is about 25 min,and the terminal total oxygen contents range from 0.002 0%to 0.002 2% after treating with SiCa wire.The best deoxidizers are SiAlBaCa and SiAlBaCaSr.展开更多
Sol-gel method was employed for the preparation of nanoscale tungsten powder. The effects of different preparation conditions on particle size were discussed and the optimum preparation condition was found. The produc...Sol-gel method was employed for the preparation of nanoscale tungsten powder. The effects of different preparation conditions on particle size were discussed and the optimum preparation condition was found. The products were characterized by X-ray diffraction, scan electron microscopy and so on. The results show that the intermediate is monoclinic WO3, its particle shape is approximately spherical, and the particle size distribution is narrow. The average particle size is about 60 nm. After deoxidization, WO3 turns into cubic tungsten powder with small particle size （average particle size about 120 nm） and narrow size distribution.展开更多
The Ti-Ni-O ternary system was assessed by means of Calphad method using ternary experimental data in previous study.Isothermal sections at 1 173 and 1 273 K were calculated.The result shows that the present calculate...The Ti-Ni-O ternary system was assessed by means of Calphad method using ternary experimental data in previous study.Isothermal sections at 1 173 and 1 273 K were calculated.The result shows that the present calculated results are in good agreement with most of the experimental results.The consistent model parameter set determined in this work may provide theoretical guidance for the deoxidation of TiNi alloy.展开更多
The influence of calcium treatment on non-metallic inclusions had been studied when control technology of refining top slag in ladle furnace was used in ultra-low oxygen steelmaking. A sufficient amount aluminium was ...The influence of calcium treatment on non-metallic inclusions had been studied when control technology of refining top slag in ladle furnace was used in ultra-low oxygen steelmaking. A sufficient amount aluminium was added to experimental heats for final deoxidizing during BOF tapping, and the refining top slag with strong reducibility, high basicity and high Al2O3 in ladle furnace was used to produce ultra-low oxygen steel and the transformation of nonmetallic inclusions in molten steel was compared by calcium treatment and no calcium treatment. The results show that the transformation of Al2O3--MgO - Al2O3 spinel-CaO-MgO-Al2O3 complex inclusions has been completed for aluminum deoxidation products and calcium treatment to molten steel is unnecessary when using the control technology of ladle furnace refining top slag to produce ultra-low oxygen steel, and the complex inclusions are liquid at the temperature of steelmaking and easily removable to obtain very high cleanliness steel by flotation. Further- more, the problems of nozzle clogging in casting operations do not happen and the remaining oxide inclusions in steel are the relatively lower melting point complex inclusions.展开更多
Effect of Mg addition on the compositions of inclusions were studied. The results show that Mg can minimize the inclusions of steel obviously. Under the present condition, Mg deoxidation products of low-S content expe...Effect of Mg addition on the compositions of inclusions were studied. The results show that Mg can minimize the inclusions of steel obviously. Under the present condition, Mg deoxidation products of low-S content experimental steel would be changed in the order of Al2O3→MgAl2O4→Mg–Al–O–S→Mg–O–S. Mg deoxidation products of high-S content experimental steel generate Mg–S(–O)+MnS type inclusions, except for usual oxysulfide. And it is consistent with the results of thermodynamics calculation. Mg is preferred to react with oxide, compared with sulfide. The reaction reaches the equilibrium after 1 min or 5 min. It shows that the number and diameter of inclusions in all experimental steel samples are well under control, helping to improve the properties of steel.展开更多
The effects of Mg content, inclusion size, and austenite grain size on the intragranular acicular ferrite （IAF） nucleation in heat-affected zone of steel plate after high-heat-input welding of 400 kJ/cm were investi...The effects of Mg content, inclusion size, and austenite grain size on the intragranular acicular ferrite （IAF） nucleation in heat-affected zone of steel plate after high-heat-input welding of 400 kJ/cm were investigated by welding simulation and observation using a scanning electron microscope equipped with an energy dispersive spectrometer and an optical microscope. The IAFs are observed in steel with Mg addition, and the volume fraction of IAF is as high as 55.4% in the steel containing 0.0027 mass% Mg. The MgO-Al2O3-Ti2O3-MnS inclusions with size around 2 μm are effective nucleation sites for IAF, whereas Al2O3-MnS inclusions are impotent to nucleate the acicular ferrite. The prior-austenite grain （PAG） size distribution in low Mg steel is similar to that in steel without Mg addition. The austenite grain with size about 200 μm is favorable for the IAF formation. In the steel with high Mg content of 0.0099%, the growth of PAG is greatly inhibited, and PAG sizes are smaller than 100 μm. Therefore, the nucleation of IAF can hardly be observed.展开更多
基金the financial support from the Anhui Key Laboratory of Low Carbon Metallurgy and Solid Waste Resource Utilization(Anhui University of Technology)(No.SKF23-01)Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education,Wuhan University of Science and Technology(No.FMRUlab23-1010)+1 种基金Open Project of State Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS 2022-07)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200).
文摘The effect of the initial(Al+Si)/MnO molar ratio and slag composition on MnO recovery from electroslag by remelting at 1773 K was investigated.High-purity aluminum metal and silicon were employed as the deoxidizers to effectively promote the recovery of manganese metal(MM).The reduction of MnO in slag,through the interaction between molten MM with a deoxidizer and the Na_(2)O-enriched electroslag melt,was assessed both thermodynamically and kinetically.The sulfur content of high-sulfur rejected electrolytic manganese metal(EMM)scrap decreased to 0.58%with high-temperature pretreatment.The mass ratio between slag and high-sulfur rejected EMM scrap is 2/3.When the Al_(2)O_(3)content in the initial slags decreased and the Na_(2)O content increased,the MnO reduction ratio increased.The residual MnO concentration of the slag reduced with increasing the Al–Si deoxidizer content.When the(Al+Si)/MnO molar ratio reached 0.83,the MnO concentration in the final slag was only 3%.A deoxidizer mainly containing aluminum and a small amount of Si could be added to recover MnO from the slag,resulting in the improvement in the cleanliness of final Mn metal.
基金support from the National Natural Science Foundation of China (No. U1960202)the Opening Foundation from Shanghai Engineering Research Center of Hot Manufacturing, China (No. 18DZ2253400)。
文摘This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two experimental shipbuilding steels after being subjected to high-heat input welding at 400 kJ·cm^(-1).The base metals (BMs) of both steels contained three types of precipitates Type Ⅰ:cubic (Ti,Nb)(C,N),Type Ⅱ:precipitate with cubic (Ti,Nb)(C,N) core and Nb-rich cap,and Type Ⅲ:ellipsoidal Nb-rich precipitate.In the BM of 60Al and 160Al steels,the number densities of the precipitates were 11.37×10^(5) and 13.88×10^(5) mm^(-2),respectively The 60Al and 160Al steel contained 38.12% and 6.39% Type Ⅲ precipitates,respectively.The difference in the content of Type Ⅲ precipitates in the 60Al steel reduced the pinning effect at the elevated temperature of the CGHAZ,which facilitated the growth of PAGs The average PAG sizes in the CGHAZ of the 60Al and 160Al steels were 189.73 and 174.7μm,respectively.In the 60Al steel,the low lattice mismatch among Cu_(2)S,TiN,and γ-Al_(2)O_(3)facilitated the precipitation of Cu_(2)S and TiN onto γ-Al_(2)O_(3)during welding,which decreased the number density of independently precipitated (Ti,Nb)(C,N) particles but increased that of γ-Al_(2)O_(3)–Ti N–Cu_(2)S particles.Thus abnormally large PAGs formed in the CGHAZ of the 60Al steel,and they reached a maximum size of 1 mm.These PAGs greatly reduced the microstructural homogeneity and consequently decreased the impact toughness from 134 (0.016wt%Al) to 54 J (0.006wt%Al)at-40℃.
文摘Microstructures and inclusions in the Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of the inclusions were analyzed using a field emission scanning electron microscope （FE-SEM） with energy dispersive X-ray spectrometry （EDS）. The kind and composition of the inclusions calculated from the thermodynamic database were in good agreement with the experimental results. There were two main kinds of inclusions formed in the Si-Mn-Ti deoxidized steels. One kind of inclusion was the manganese titanium oxide （Mn-Ti oxide）. Another kind of inclusion was the MnS inclusion with segregation points containing Ti and N. According to the thermodynamic calculation, those segregation points were TiN precipitates. The formation of intragranular ferrite （IGF） microstructures refined the grain size during the austenite-ferrite transformation. The mechanisms of IGF formation were discussed. Mn-Ti oxide inclusions with Mn-depleted zone （MDZ） were effective to be nucleation sites for IGF formation, because the MDZ increased the austenite-ferrite transformation temperature. TiN had the low misfit ratio with IGF, so the TiN precipitated on the MnS surface also promoted the formation of IGF because of decreasing interfacial energies.
基金The present work was financially supported by the National Natural Science Foundation of China(Nos.52074207 and 51874081)Key Laboratory of Ecological Metallurgy of Multimetallic Mineral(Northeastern University)of Ministry of Education.
文摘The effects of different hot deformation amounts on the evolution of inclusion and microstructure in Ti-Zr deoxidized steel were studied by utilizing the Thermecmaster-Z hot simulation test machine,automatic scanning electron microscope equipped with energy-dispersive spectrometer,and electron backscattered diffraction.The results indicated that hot deformation amount has no significant effect on the number density of oxide,but the MnS that precipitated on the Ti-Zr oxide surface undergoes extension and breakage,resulting in the changes in oxide aspect ratio.Moreover,the fracture of nitride mainly occurs in the sample with the second pass deformation amount of 42.9%and 71.4%,and the degree of fragmentation of nitride is more serious with the deformation amount increasing.During the hot compression,sulfide undergoes breakage and extension,and with the second pass deformation amount increasing,the breakage and extension of sulfide present a periodic change.Finally,with the increase in hot compression amount,the ferrite types in microstructure change from acicular ferrite and bainitic ferrite to polygonal ferrite,and the ferrite grain size is refined.When the total deformation amount increases from 30%to 80%,the ferrite grain sizes of grain boundary with the misorientation of 4°and 15°decrease from 4.14 and 5.67μm to 3.47 and 4.40μm,respectively.However,when the total deformation amount increases to 80%,the harmful ferrite/pearlite banded structure appears in the micro structure.Refining ferrite grain size and avoiding harmful microstructure are the key for the optimization of hot compression process.
基金supported by the National Natural Science Foundation of China(Nos.52274341 and 51974210).
文摘To avoid coarse crystallization of glassy inclusions in Si–Mn deoxidized steel during hot rolling, the effect of MgO on the structure and crystallization behavior of CaO–SiO_(2)–Al_(2)O_(3) inclusions was investigated. The results showed that the crystallization temperature of the oxide melts decreased with increasing MgO content from 0 to 15.7 wt.%, which suggested that the addition of MgO would increase the temperature range of the crystalline transition. The increase in MgO content could decrease the crystallization activation energy of inclusions. With the increase in MgO content, the relative fractions of O_(Si)^(0) and O_(Si)^(1) structure units increased, and those of structure units O_(Si)^(2), O_(Si)^(3), and O_(Si)^(4) decreased, increasing the depolymerization degree of the silicate structure. The crystallization ratio of glassy inclusions in the steel crucible increased from 19.7% to 98.3% with increasing MgO content from 0 to 15.7 wt.%. The addition of MgO improved the crystallization ability of inclusions, because MgO provides free oxygen O_(2−) to destroy the bridging oxygens and form non-bridging oxygens O^(−), which depolymerizes silicate network structure and simplifies the [SiO_(4)]-tetrahedral structure. In addition, MgO would promote the precipitation of the Mg-containing phases with a high melting point. When the MgO content was increased above 12.1 wt.%, MgO·Al_(2)O_(3) and 2MgO·SiO_(2) crystalline phases would precipitate from the inclusions.
文摘Because there are a lot of influences of alumina inclusions on the performance of rail steel,it is reasonable to adopt the deoxidization method with Al-free deoxidizer. According to the characteristics of Al-free deoxidization process,the control of aluminum content,the deoxidization with ladle furnace（LF） slag,the deoxidization process under vacuum by carbon,and the inclusions modification technology by calcium treatment were studied. All of them were applied to practical production. The results indicate that the adoption of Al-free deoxidization process leads to the total oxygen content in the steel below 20 ppm,which meets the requirement of clean rail steel.
文摘Aiming at the nozzle blocking problem in rectangular bloom production, analyze the reason, and put forword to using non-aluminium producing process to solve this problem. By analysis the experiment data, that indicate using non-aluminium process we can get good desulfurization and white slag, also get good castability and best quality. This process can fulfill the requirement of produce, it is reasonable and feasible.
文摘Complex deoxidizer is an important supplementary material for steelmaking,which can not only absorb liquid steel inclusions and improve the quality of molten steel,but also enhance deoxidation,desulfurization, dephosphorization,to prevent the molten steel suction and reduce the molten steel temperature loss.Currently,the complex deoxidizer all contain a certain amount of metal aluminium.The metal aluminium can not be determined for the steel.The entire aluminium contents were regarded as the content of approximate metal aluminium,that often bring great economic losses.Because A1,0,price is cheaper than metal aluminite powder,suppliers added a certain amount of Al_2O_3 in complex deoxidizer,pretend to be the metal aluminium to reap huge profits.This paper put forward a kind of method for determining aluminum,which would reduce loss of the enterprise.Research and put forward an iron triehloride,which extracted from Al metal from complex deoxidizer.Meantime,using orthogonal design of the experiment has been optimized for working conditions.The RSD of the samples are I. 07%-1.94%,the recoveries of the experiment results are 97.0%-110.0%,which expressed the precision and accuracy of the experiment are good.The establishment of the iron triehloride as a extractor,which is rapid and accurate for determination of Al metal in complex deoxidizer.
文摘Mn-Ti oxides in Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of inclusions were analyzed by using FE-SEM with EDS. Mn-Ti oxides were found to be effective sites to induce intragranular ferrite formation. The thermodynamic calculation was employed to interpret the critical condition for Mn-Ti oxide formation. Mn-Ti oxide formation was controlled not only by Mn and Ti content, but also by total oxygen content in steel. When the Mn and Ti contents were around 1.5% and 0. 005% --0.01%, respectively, Mn-Ti oxide could form as the total oxygen content was 0. 001%- 0. 002 %. The experimental results were in good agreement with thermodynamic calculation results. Also, MnS solubilit：（ was examined in Mn-Ti oxide inclusion system. With an increase of MnO content in Mn-Ti oxide, MnS solubility in the oxides increased. MnS precipitation benefited from high MnO content in Mn-Ti oxide.
文摘The electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,the intrinsic complexity of this multi-step reaction severely constrains both the selectivity and efficiency of NO3RR.Copper-based electrocatalysts have been extensively investigated for NO_(3)RR but often suffer from nitrite(NO_(2)^(−))accumulation,which stems from insufficient NO_(3)^(−)adsorption strength.This limitation often leads to rapid catalyst deactivation,hindered hydrogenation pathways,and reduced overall efficiency.Herein,we report a one-step green chemical reduction method to synthesize PtCuSnCo quarternary alloy nanoparticles with homogeneously distributed elements.Under practical NO3−concentrations,the optimized catalyst exhibited an impressive Faradaic efficiency approaching 100%and an outstanding selectivity of 95.6±2.9%.Mechanistic insights uncovered that SnCo sites robustly facilitated NO_(3)^(−)adsorption,complemented by the proficiency of PtCu sites in NO3−reduction.The synergistic spatial neighborhood effect between SnCo and PtCu sites efficiently stabilizes NO_(3)^(−)deoxygenation and suppresses NO_(2)^(−)accumulation.This tandem architecture achieves a finely tuned balance between adsorption strength and deoxygenation kinetics,enabling highly selective and efficient NO3RR.Our findings emphasize the indispensable role of engineered multi-metallic catalysts in overcoming persistent challenges of NO3RR,paving the way for advanced NH3 synthesis and environmental remediation.
基金supported by the National Natural Science Foundation of China,Pilot Group Program of the Research Fund for International Senior Scientists(22250710676)National Natural Science Foundation of China(22078064,22378062,22304028)+1 种基金Natural Science Foundation of Fujian Province(2021J02009)Tianjin University-Fuzhou University Independent Innovation Fund Cooperation Project(TF2023-1,TF2023-8).
文摘In recent years,studies focusing on the conversion of renewable lignin-derived oxygenates(LDOs)have emphasized their potential as alternatives to fossil-based products.However,LDOs,existing as complex aromatic mixtures with diverse oxygen-containing functional groups,pose a challenge as they cannot be easily separated via distillation for direct utilization.A promising solution to this challenge lies in the efficient removal of oxygen-containing functional groups from LDOs through hydrodeoxygenation(HDO),aiming to yield biomass products with singular components.However,the high dissociation energy of the carbon-oxygen bond,coupled with its similarity to the hydrogenation energy of the benzene ring,creates a competition between deoxygenation and benzene ring hydrogenation.Considering hydrogen consumption and lignin properties,the preference is directed towards generating aromatic hydrocarbons rather than saturated components.Thus,the goal is to selectively remove oxygen-containing functional groups while preserving the benzene ring structure.Studies on LDOs conversion have indicated that the design of active components and optimization of reaction conditions play pivotal roles in achieving selective deoxygenation,but a summary of the correlation between these factors and the reaction mechanism is lacking.This review addresses this gap in knowledge by firstly summarizing the various reaction pathways for HDO of LDOs.It explores the impact of catalyst design strategies,including morphology modulation,elemental doping,and surface modification,on the adsorption-desorption dynamics between reactants and catalysts.Secondly,we delve into the application of advanced techniques such as spectroscopic techniques and computational modeling,aiding in uncovering the true active sites in HDO reactions and understanding the interaction of reactive reactants with catalyst surface-interfaces.Additionally,fundamental insights into selective deoxygenation obtained through these techniques are highlighted.Finally,we outline the challenges that lie ahead in the design of highly active and selective HDO catalysts.These challenges include the development of detection tools for reactive species with high activity at low concentrations,the study of reaction medium-catalyst interactions,and the development of theoretical models that more closely approximate real reaction situations.Addressing these challenges will pave the way for the development of efficient and selective HDO catalysts,thus advancing the field of renewable LDOs conversion.
基金supported by the National Natural Science Foundation of China(No.U21A20113)the Natural Science Foundation of Hubei Province of China(No.2021CFA023).
文摘A low-carbon,low-cost,and high-efficient method was reported for remarkably improving corrosion resistance of C–Mn structural steel by weak deoxidation.The results showed that,with the total oxygen content(wOT)increasing in the tested steel from 41×10^(−6)to 195×10^(−6),both the degree of element segregation and the level of banded microstructure weakened,presenting the lower potential difference between pearlite(P)and ferrite(F),and then smaller galvanic corrosion driving force,and thus effectively improving general corrosion properties.In addition,with wOT growing up,the number and size of inclusions increased,and the shape also changed from long chain or small particle to large particle ball with typical mosaic structure,which could effectively inhibit the preferential dissolution of local component due to multiple complex interfaces,and correspondingly suppress the pitting susceptibility.However,the impact toughness at low temperature of the tested steel reduced with wOT increasing,and then,taking the mechanical properties and corrosion resistance all into account,160×10^(−6) was the optimal oxygen content within the present scope.
基金financially supported by the National Natural Science Foundation of China (No.52174297)。
文摘In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the steel liquid,affecting the cleanliness of the steel.With the increasing requirements for steel performance,reducing the oxygen content in the steel liquid and ensuring its high cleanliness is necessary.After more than a hundred years of development,the total oxygen content in steel has been reduced from approximately 100×10^(-6)to approximately 10×10^(-6),and it can be controlled below 5×10^(-6)in some steel grades.A relatively stable and mature deoxidation technology has been formed,but further reducing the oxygen content in steel is no longer significant for improving steel quality.Our research team developed a deoxidation technology for bearing steel by optimizing the entire conventional process.The technology combines silicon–manganese predeoxidation,ladle furnace diffusion deoxidation,and vacuum final deoxidation.We successfully conducted industrial experiments and produced interstitial-free steel with natural decarbonization predeoxidation.Non-aluminum deoxidation was found to control the oxygen content in bearing steel to between 4×10^(-6) and 8×10^(-6),altering the type of inclusions,eliminating large particle Ds-type inclusions,improving the flowability of the steel liquid,and deriving a higher fatigue life.The natural decarbonization predeoxidation of interstitial-free steel reduced aluminum consumption and production costs and significantly improved the quality of cast billets.
基金Item Sponsored by National Natural Science Foundation of China(59874014)Foundation of Science and Technology for Excellent Youth of Anhui Province of China
文摘The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi 2 furnace at 1 873 K. The total oxygen contents of molten steel, the distribution, size and morphology of deoxidation products in the steel were surveyed. The metamorphic mechanism for deoxidation products of alloy bearing barium was also discussed. The results show that applying alloy bearing barium to the pipe steel, very low total oxygen contents can be obtained, and deoxidation products, which easily float up from molten steel, can be changed into globular shape and uniformly distributed in steel. The equilibrium time of total oxygen is about 25 min, and the terminal total oxygen contents range from 0 002 0 % to 0 002 2 % after treating with SiCa wire. The best deoxidizers are SiAlBaCa and SiAlBaCaSr.
基金Item Sponsored by National Natural Science Foundation of China(50174012)Baoshan Iron and Steel Group Co
文摘The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi2 furnace at 1 873 K.The total oxygen contents of molten steel,the distribution,size and morphology of deoxidation products in the steel were surveyed.The metamorphic mechanism for deoxidation products of alloy bearing barium was also discussed.The results show that applying alloy bearing barium to the pipe steel,very low total oxygen contents can be obtained,and deoxidation products,which easily float up from molten steel,can be changed into globular shape and uniformly distributed in steel.The equilibrium time of total oxygen is about 25 min,and the terminal total oxygen contents range from 0.002 0%to 0.002 2% after treating with SiCa wire.The best deoxidizers are SiAlBaCa and SiAlBaCaSr.
文摘Sol-gel method was employed for the preparation of nanoscale tungsten powder. The effects of different preparation conditions on particle size were discussed and the optimum preparation condition was found. The products were characterized by X-ray diffraction, scan electron microscopy and so on. The results show that the intermediate is monoclinic WO3, its particle shape is approximately spherical, and the particle size distribution is narrow. The average particle size is about 60 nm. After deoxidization, WO3 turns into cubic tungsten powder with small particle size （average particle size about 120 nm） and narrow size distribution.
基金Project (10520706400) supported by the Science and Technology Commission of Shanghai Municipality,ChinaProject (2007CB613606) supported by the National Basic Research Program of ChinaProjects (50774052,51074105) supported by the National Natural Science Foundation of China
文摘The Ti-Ni-O ternary system was assessed by means of Calphad method using ternary experimental data in previous study.Isothermal sections at 1 173 and 1 273 K were calculated.The result shows that the present calculated results are in good agreement with most of the experimental results.The consistent model parameter set determined in this work may provide theoretical guidance for the deoxidation of TiNi alloy.
基金Item Sponsored by National Basic Research Program of China(2010CB630806)
文摘The influence of calcium treatment on non-metallic inclusions had been studied when control technology of refining top slag in ladle furnace was used in ultra-low oxygen steelmaking. A sufficient amount aluminium was added to experimental heats for final deoxidizing during BOF tapping, and the refining top slag with strong reducibility, high basicity and high Al2O3 in ladle furnace was used to produce ultra-low oxygen steel and the transformation of nonmetallic inclusions in molten steel was compared by calcium treatment and no calcium treatment. The results show that the transformation of Al2O3--MgO - Al2O3 spinel-CaO-MgO-Al2O3 complex inclusions has been completed for aluminum deoxidation products and calcium treatment to molten steel is unnecessary when using the control technology of ladle furnace refining top slag to produce ultra-low oxygen steel, and the complex inclusions are liquid at the temperature of steelmaking and easily removable to obtain very high cleanliness steel by flotation. Further- more, the problems of nozzle clogging in casting operations do not happen and the remaining oxide inclusions in steel are the relatively lower melting point complex inclusions.
基金Item Sponsored by National Natural Science Foundation of China(50904017)Fundamental Research Funds for the Central Universities of China(N120502004,N120602005)
文摘Effect of Mg addition on the compositions of inclusions were studied. The results show that Mg can minimize the inclusions of steel obviously. Under the present condition, Mg deoxidation products of low-S content experimental steel would be changed in the order of Al2O3→MgAl2O4→Mg–Al–O–S→Mg–O–S. Mg deoxidation products of high-S content experimental steel generate Mg–S(–O)+MnS type inclusions, except for usual oxysulfide. And it is consistent with the results of thermodynamics calculation. Mg is preferred to react with oxide, compared with sulfide. The reaction reaches the equilibrium after 1 min or 5 min. It shows that the number and diameter of inclusions in all experimental steel samples are well under control, helping to improve the properties of steel.
文摘The effects of Mg content, inclusion size, and austenite grain size on the intragranular acicular ferrite （IAF） nucleation in heat-affected zone of steel plate after high-heat-input welding of 400 kJ/cm were investigated by welding simulation and observation using a scanning electron microscope equipped with an energy dispersive spectrometer and an optical microscope. The IAFs are observed in steel with Mg addition, and the volume fraction of IAF is as high as 55.4% in the steel containing 0.0027 mass% Mg. The MgO-Al2O3-Ti2O3-MnS inclusions with size around 2 μm are effective nucleation sites for IAF, whereas Al2O3-MnS inclusions are impotent to nucleate the acicular ferrite. The prior-austenite grain （PAG） size distribution in low Mg steel is similar to that in steel without Mg addition. The austenite grain with size about 200 μm is favorable for the IAF formation. In the steel with high Mg content of 0.0099%, the growth of PAG is greatly inhibited, and PAG sizes are smaller than 100 μm. Therefore, the nucleation of IAF can hardly be observed.
