The fluorine-free MXene was prepared by Lewis acid salt etching of ternary layered ceramic MAX phase material.The structure of fluorine-free MXene was characterized by scanning electron microscopy(SEM)and X-ray diffra...The fluorine-free MXene was prepared by Lewis acid salt etching of ternary layered ceramic MAX phase material.The structure of fluorine-free MXene was characterized by scanning electron microscopy(SEM)and X-ray diffractometry(XRD).The study finds that the layer spacing of fluorine-free MXene is approximately twice that of MXene etched by the liquid-phase method,compared to the conventional liquidphase method.It also has greater capacitive properties.Therefore,the MXene prepared by this method shows a great potential for application in the field of capacitors.展开更多
Fluorine-free electrolytes have attracted great attention because of its low-cost and environmental friendliness. However, so far, little is known about the solution structures of these electrolytes. Here,we compare t...Fluorine-free electrolytes have attracted great attention because of its low-cost and environmental friendliness. However, so far, little is known about the solution structures of these electrolytes. Here,we compare the solvation phenomenon of sodium tetraphenylborate(NaBPh_(4)) salt dissolved in organic solvents of propylene carbonate(PC), 1,2-dimethoxyethane(DME), acetonitrile(ACN) and tetrahydrofuran(THF). Small-angle X-ray scattering(SAXS) reveals a unique two-peak structural feature in this saltconcentrated PC electrolyte, while solutions using other solvents only have one scattering peak.Molecular dynamics(MD) simulations further reveal that there are anion-based clusters in addition to the short-range charge ordering in the concentrated NaBPh4/PC electrolyte. Raman spectroscopy confirms the existence of considerable contact ion pairs(CIPs). This work emphasizes the importance of global and local structural analysis, which will provide valuable clues for understanding the structureperformance relationship of electrolytes.展开更多
Mold flux serves the crucial metallurgical function of absorbing inclusions, directly impacting the smoothness of the casting process as well as the cast slab quality. In this study, the dissolution behavior and mecha...Mold flux serves the crucial metallurgical function of absorbing inclusions, directly impacting the smoothness of the casting process as well as the cast slab quality. In this study, the dissolution behavior and mechanism of Ti O_(2)and Ti N inclusions in molten Ca O–Si O_(2)–B_(2)O_(3)-based fluorine-free mold flux were explored by in situ single hot thermocouple technology combined with X-ray photoelectron spectroscopy.The results showed that Ti O_(2) inclusions are effectively dissolved by the molten slag within 76 s, during which the original octahedral [Ti O_(6)]^(8-)structures are destroyed and convert to the networker tetrahedral [Ti O_(4)]^(4-)structures. However, the dissolution rate is much lower for Ti N inclusions than for Ti O_(2)inclusions. This can be attributed to the fact that the Ti N particles need to be oxidized and then dissolved in the molten slag to form tetrahedral [Ti O4]4-and octahedral [Ti O_(6)]^(8-)structures during the Ti N inclusion dissolution process, which is accompanied by the generation of a large amount of N_(2)gas. Moreover, Ca Ti O_(3)crystals tend to nucleate and grow on bubble surfaces with sufficient octahedral [Ti O_(6)]^(8-)structures and Ca^(2+)ions, eventually resulting in the molten slag being in a solid–liquid mixed state.展开更多
Fluorine in mold powder is known as harmful to human health and the environment. Being the advocate of green production, Baosteel developed an environmentally friendly mold powder without fluorine. The main problem of...Fluorine in mold powder is known as harmful to human health and the environment. Being the advocate of green production, Baosteel developed an environmentally friendly mold powder without fluorine. The main problem of fluorine-free flux film is small heat resistance and thus the heat transfer intensity of the mold is too large, which to some extent hinders the increase of the casting speed. With the heat flow simulation equipment, controlling precipitation of crystal in flux and solidification temperature properly, fluorine-free mold powder for low carbon steel,which substitutes F with B203 ,was successfully developed and applied in industrial production. The production results show that, by using boronic fluorine-free mold powder,the boron increment in molten steel is less than 1.3ppm for conventional aluminium killed low carbon steel.展开更多
Fluorinated salts and/or high salt concentrations are usually necessary to produce protective films on the electrodes for high-voltage aqueous batteries,yet these approaches increase the cost,toxicity and reaction res...Fluorinated salts and/or high salt concentrations are usually necessary to produce protective films on the electrodes for high-voltage aqueous batteries,yet these approaches increase the cost,toxicity and reaction resistances of battery.Herein,we report a dilute fluorine-free electrolyte design to overcome this dilemma.By using the LiClO_(4) salt and polyethylene glycol dimethyl ether(PED)solvent and optimizing the LiClO_(4)/PED/H_(2)O molar ratio,we formulate a 1 mol kg^(-1)3 V-class hybrid aqueous electrolyte that enables reversible charge/discharge of 2.5 V LiMn_(2)O_(4)|Li_(4)Ti_(5)O_(12) full cell at both low(0.5C,92.4%capacity retention in 300 cycles)and high(5C,80.4%capacity retention in 2000 cycles)rates.This excellent performance is reached even without the generation of protective film on either anode or cathode as identified by in/ex situ characterizations.The selection of appropriate ingredients that have both high stability and strong interactions with water is critical to widen the potential window of electrolyte while suppressing parasitic reactions on the electrodes.This work suggests that expensive and toxic fluorinate salts are no longer necessary for 3 V-class aqueous electrolytes,boosting the development of low-cost,environmentally-friendly,high-power and high-energy-density aqueous batteries.展开更多
目前,浏览器已经成为人们接入互联网最主要的入口。HTML5、JavaScript和CSS等Web技术的发展,也极大地增强了Web应用的功能并丰富了用户的交互体验。但是,随着Web应用逻辑日益复杂,人们既要经常完成过程繁琐且需重复执行的任务,也要完成...目前,浏览器已经成为人们接入互联网最主要的入口。HTML5、JavaScript和CSS等Web技术的发展,也极大地增强了Web应用的功能并丰富了用户的交互体验。但是,随着Web应用逻辑日益复杂,人们既要经常完成过程繁琐且需重复执行的任务,也要完成操作复杂且难以记忆的任务。因此,基于目前流行的Chrome浏览器,设计实现了一个动作捕捉与回放工具Scratch(Smart Capture-and-Replay at Chrome),以实现对Web应用操作正确、一致的捕捉与回放,并允许其他用户对已有操作记录进行定制。展开更多
The high chrome bricks specimens were prepared by firing at 1 350,1 450 and 1 550 ℃ in carbon embedded condition and at 1 700 ℃ in air,respectively. Effects of firing atmospheres （carbon embedded and air） on bulk ...The high chrome bricks specimens were prepared by firing at 1 350,1 450 and 1 550 ℃ in carbon embedded condition and at 1 700 ℃ in air,respectively. Effects of firing atmospheres （carbon embedded and air） on bulk density,apparent porosity,cold crushing strength,and slag penetration resistance of high chrome bricks were researched in order to improve physical properties and corrosion resistance of high chrome bricks and to prolong the service life in slagging coal gasifier. The results show that with temperature rising,the apparent porosity of specimens decreases and the bulk density increases; the cold crushing strength of the specimens carbon embedded fired at 1 450 ℃ is the highest,reaching 214 MPa; carbon embedded condition is beneficial to reducing the sintering temperature and improving the microstructure; the specimens carbon embedded fired at 1 450 ℃ perform better slag penetration resistance than the specimens fired at 1 700 ℃ in air.展开更多
基金Funded by the National Natural Science Foundation of China Youth Program (51302073)the Green Light Materials Hubei Key Laboratory Open Fund (202027B11)。
文摘The fluorine-free MXene was prepared by Lewis acid salt etching of ternary layered ceramic MAX phase material.The structure of fluorine-free MXene was characterized by scanning electron microscopy(SEM)and X-ray diffractometry(XRD).The study finds that the layer spacing of fluorine-free MXene is approximately twice that of MXene etched by the liquid-phase method,compared to the conventional liquidphase method.It also has greater capacitive properties.Therefore,the MXene prepared by this method shows a great potential for application in the field of capacitors.
基金supported as part of the Joint Center for Energy Storage Research,an Energy Innovation Hub funded by the U.S.Department of Energy,Office of Science,Basic Energy Sciencesthe supported by U.S.National Science Foundation(Grant No.2120559)。
文摘Fluorine-free electrolytes have attracted great attention because of its low-cost and environmental friendliness. However, so far, little is known about the solution structures of these electrolytes. Here,we compare the solvation phenomenon of sodium tetraphenylborate(NaBPh_(4)) salt dissolved in organic solvents of propylene carbonate(PC), 1,2-dimethoxyethane(DME), acetonitrile(ACN) and tetrahydrofuran(THF). Small-angle X-ray scattering(SAXS) reveals a unique two-peak structural feature in this saltconcentrated PC electrolyte, while solutions using other solvents only have one scattering peak.Molecular dynamics(MD) simulations further reveal that there are anion-based clusters in addition to the short-range charge ordering in the concentrated NaBPh4/PC electrolyte. Raman spectroscopy confirms the existence of considerable contact ion pairs(CIPs). This work emphasizes the importance of global and local structural analysis, which will provide valuable clues for understanding the structureperformance relationship of electrolytes.
基金financially supported by the Fellowship of China National Postdoctoral Program for Innovative Talents(No.BX20220357)the National Science Foundation of China (No.52130408)。
文摘Mold flux serves the crucial metallurgical function of absorbing inclusions, directly impacting the smoothness of the casting process as well as the cast slab quality. In this study, the dissolution behavior and mechanism of Ti O_(2)and Ti N inclusions in molten Ca O–Si O_(2)–B_(2)O_(3)-based fluorine-free mold flux were explored by in situ single hot thermocouple technology combined with X-ray photoelectron spectroscopy.The results showed that Ti O_(2) inclusions are effectively dissolved by the molten slag within 76 s, during which the original octahedral [Ti O_(6)]^(8-)structures are destroyed and convert to the networker tetrahedral [Ti O_(4)]^(4-)structures. However, the dissolution rate is much lower for Ti N inclusions than for Ti O_(2)inclusions. This can be attributed to the fact that the Ti N particles need to be oxidized and then dissolved in the molten slag to form tetrahedral [Ti O4]4-and octahedral [Ti O_(6)]^(8-)structures during the Ti N inclusion dissolution process, which is accompanied by the generation of a large amount of N_(2)gas. Moreover, Ca Ti O_(3)crystals tend to nucleate and grow on bubble surfaces with sufficient octahedral [Ti O_(6)]^(8-)structures and Ca^(2+)ions, eventually resulting in the molten slag being in a solid–liquid mixed state.
文摘Fluorine in mold powder is known as harmful to human health and the environment. Being the advocate of green production, Baosteel developed an environmentally friendly mold powder without fluorine. The main problem of fluorine-free flux film is small heat resistance and thus the heat transfer intensity of the mold is too large, which to some extent hinders the increase of the casting speed. With the heat flow simulation equipment, controlling precipitation of crystal in flux and solidification temperature properly, fluorine-free mold powder for low carbon steel,which substitutes F with B203 ,was successfully developed and applied in industrial production. The production results show that, by using boronic fluorine-free mold powder,the boron increment in molten steel is less than 1.3ppm for conventional aluminium killed low carbon steel.
基金supported by the Westlake Education Foundation and National Natural Science Foundation of China(21975207)。
文摘Fluorinated salts and/or high salt concentrations are usually necessary to produce protective films on the electrodes for high-voltage aqueous batteries,yet these approaches increase the cost,toxicity and reaction resistances of battery.Herein,we report a dilute fluorine-free electrolyte design to overcome this dilemma.By using the LiClO_(4) salt and polyethylene glycol dimethyl ether(PED)solvent and optimizing the LiClO_(4)/PED/H_(2)O molar ratio,we formulate a 1 mol kg^(-1)3 V-class hybrid aqueous electrolyte that enables reversible charge/discharge of 2.5 V LiMn_(2)O_(4)|Li_(4)Ti_(5)O_(12) full cell at both low(0.5C,92.4%capacity retention in 300 cycles)and high(5C,80.4%capacity retention in 2000 cycles)rates.This excellent performance is reached even without the generation of protective film on either anode or cathode as identified by in/ex situ characterizations.The selection of appropriate ingredients that have both high stability and strong interactions with water is critical to widen the potential window of electrolyte while suppressing parasitic reactions on the electrodes.This work suggests that expensive and toxic fluorinate salts are no longer necessary for 3 V-class aqueous electrolytes,boosting the development of low-cost,environmentally-friendly,high-power and high-energy-density aqueous batteries.
基金教育部人文社会科学重点研究基地重大项目(编号:12JJD880013)“教学伦理学研究”加拿大Social Sciences and Humanities Research Council(SSHRC)政府资助项目+2 种基金天津市2013年度哲学社会科学规划课题(编号:TJJX13-010)“中小学信息化课程资源的校际共享机制研究”国家教师科研“十二五”全国重点课题(编号:KT0801958A-XXX)“`课程改进-教学跟进`式学校发展研究”北京市教育科学“十二五”规划重点课题(编号:ABA14010)“信息化条件下北京市中小学学生学习方式变革实验研究”阶段性研究成果
文摘目前,浏览器已经成为人们接入互联网最主要的入口。HTML5、JavaScript和CSS等Web技术的发展,也极大地增强了Web应用的功能并丰富了用户的交互体验。但是,随着Web应用逻辑日益复杂,人们既要经常完成过程繁琐且需重复执行的任务,也要完成操作复杂且难以记忆的任务。因此,基于目前流行的Chrome浏览器,设计实现了一个动作捕捉与回放工具Scratch(Smart Capture-and-Replay at Chrome),以实现对Web应用操作正确、一致的捕捉与回放,并允许其他用户对已有操作记录进行定制。
文摘The high chrome bricks specimens were prepared by firing at 1 350,1 450 and 1 550 ℃ in carbon embedded condition and at 1 700 ℃ in air,respectively. Effects of firing atmospheres （carbon embedded and air） on bulk density,apparent porosity,cold crushing strength,and slag penetration resistance of high chrome bricks were researched in order to improve physical properties and corrosion resistance of high chrome bricks and to prolong the service life in slagging coal gasifier. The results show that with temperature rising,the apparent porosity of specimens decreases and the bulk density increases; the cold crushing strength of the specimens carbon embedded fired at 1 450 ℃ is the highest,reaching 214 MPa; carbon embedded condition is beneficial to reducing the sintering temperature and improving the microstructure; the specimens carbon embedded fired at 1 450 ℃ perform better slag penetration resistance than the specimens fired at 1 700 ℃ in air.
