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Influence of in situ formed spinel in bonding phase on mechanical properties and air permeability of magnesia-chrome porous purging materials

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Journal of Iron and Steel Research International 2024年第6期31卷 1459-1472页

作者： Yi An Hao Liu zhou-fu wang Yan Ma Xi-tang wang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel ***,practical applications of magnesia-chrome porous purging materials are stil hampered by the poor scouring resistance to molten steel and unstable air permeability owing to their low mechanical properties and uncontrollable pore ***,the particle-packing type magnesiachrome porous purging materials reinforced by in situ formed spinel were prepared using fused magnesia-chrome particles and Al powders as major raw *** results show that in situ formed spinel solid solutions in bonding phase led to the decreased median pore size and increased pore surface fractal dimension from the reactions between Al powders and magnesia-chrome particles and along with high-temperature sintering,bonding between magnesia-chrome particles and the resultant mechanical properties of materials were greatly ***,the results of air permeability tests and polynomial ftting indicated that the formation of spinel solid solutions was the main contributing factor for controllable air permeability,and pressure drop of porous purging materials was positively correlated with surface fractal dimension of ***,the as-prepared porous purging materials added with 6 wt.%Al powders obtained the maximum cold crushing strength(54.2 MPa)and hot modulus of rupture(12.9 MPa)with median pore size of 24.06μm and ftting non-Darcian permeability coefficient of 0.97×10^(-6)m.

关键词： Magnesia Chrome porous purging material Metallic Al-Spinel Mechanical strength Air permeability

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Preparation of yttrium oxide coating with enhanced thermal shock resistance on refractories used for titanium alloy melting and casting

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Journal of Iron and Steel Research International 2024年第6期31卷 1411-1422页

作者： Ao Chen Yan Ma zhou-fu wang Hao Liu Xi-tang wang Sen-na Chen Chen-xin Zhang Zi-yi Tang Wei-dong fu Wei Cheng The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Xiangyang Juli High Technology Material Co. Ltd.Xiangyang 441705HubeiChina Xiangyang Public Inspection and Testing Center Xiangyang 441000HubeiChina

In order to enhance the service life of refractories for melting and casting of titanium alloy,preparation of yttrium oxide coatings on the refractories surface is an effective *** improvement of thermal shock stability of the coating is beneficial to its spalling resistance during the high-temperature service,and the available slurry with good performance is the *** effects of the varieties and contents of dispersant(sodium tripolyphosphate,sodium hexametaphosphate,sodium pyrophosphate,citric acid and polycarboxylate ammonium salt)and binder(aluminum dihydrogen phosphate,zirconium acetate and yttria sol)on the stability,rheological and thixotropic properties of yttrium oxide waterbased slurry were investigated,and the effects of slurry composition design on the thermal shock resistance of the coating were *** results showed that the introduction of polycarboxylate ammonium salt as dispersant significantly improved the stability of the slurry,and the varieties of the binders had significant effects on the dispersibility of the *** aluminum dihydrogen phosphate and polycarboxylate ammonium salt were used as binder and dispersant,respectively,the slurry had better stability,suitable rheological and thixotropic *** using aluminum dihydrogen phosphate as binder,the coating had good thermal shock resistance and no obvious cracks were observed for the coating after thermal shock,which was attributed to the yttrium aluminate binding phase generated in the *** effective method was provided for preparing yttrium oxide coatings with enhanced thermal shock resistance applied in the process of titanium alloy melting and casting.

关键词： Yttrium oxide-Slurry Stability Rheological property Thixotropic property-Coating Thermal shock resistance

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Selective sintering of magnesia-calcia materials by utilizing hot spots during induction sintering process

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Journal of Iron and Steel Research International 2024年第8期31卷 1914-1922页

作者： Yun-jie Dong zhou-fu wang Hao Liu Yan Ma Xi-tang wang Nian Yi Zhong-feng Xia Yu-xuan Zhu Cheng-ji Deng Ling Zhang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 110325LiaoningChina

Magnesia-calcia refractories are widely used in the production process of clean steel due to their excellent high-tem-perature stability,slag resistance and ability to purify molten ***,there are still problems such as difficult sintering and easy ***-calcia materials with various calcium oxide contents were prepared by using induction sintering,and the sintering property combined with the hydration resistance of the materials was *** experimental results showed that the magnesia-calcia materials prepared under induction field had higher density,microhardness and hydration *** particular,the relative density of induction sintered magnesia-calcia materials with 50 mo1%CaO was greater than 98%,and the average grain size of CaO was 4.56μm,which was much larger than that of traditional sintered *** order to clarify the densification and microstructure evolution mechanism of the magnesia-calcia materials,the changes in temperature and magnetic field throughout the sintering process were analyzed by using finite element *** results showed that the larger heating rate and higher sintering temperature under the induction sintering mode were beneficial to the rapid *** addition,the hot spots generated within the material due to the difference in high-temperature electric conductivity between MgO and CaO were the critical factor to realize selective sintering in MgO-CaO system,which provides a novel pathway to solve the problem of difficult sintering and control the microstructure of high-temperature composite material used in the field of high-purity steel smelting.

关键词： Magnesia-calcia material Induction sintering Hot spot Selective sintering Density Microstructure control Hydration resistance

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Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers

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International Journal of Minerals,Metallurgy and Materials 2017年第11期24卷 1335-1340页

作者： Hao Liu Nan Wei zhou-fu wang Xi-tang wang Yan Ma The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and Technology Wuhan 430081 China

To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K_2Ti_6O_(13) whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol–gel process. During the preparation process, the fiber surface was coated with K_2Ti_6O_(13) whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K_2Ti_6O_(13) whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.

关键词： aluminum silicate fiber potassium hexatitanate whiskers compressive strength thermal conductivity

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Enhanced slag resistance and mechanical properties of magnesia castables with strontium carbonate addition

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Journal of Iron and Steel Research International 2023年第10期30卷 2021-2030页

作者： Hao Liu Yu-xuan Zhu zhou-fu wang Yan Ma Xi-tang wang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

Magnesia castables have been widely used in metallurgical industries with the advantages of high refractoriness,non-polluting steel,and resistance to alkaline *** castables were prepared using strontium carbonate(SrCO_(3))as additive to enhance slag resistance and mechanical properties,and the influence of SrCO_(3) on the evolution of phases,microstructure and properties of magnesia castables sintered at different temperatures was *** results show that,with the introduction of SrCO_(3)(lower than 3 wt.%),elastic modulus,mechanical strength,thermal shock resistance and densification of magnesia castables were significantly enhanced owing to the formation of needle-like Ca_(0.9)Sr_(0.1)MgSi_(2)O_(6) phase and liquid phase when sintering at high temperatures,and the introduced SrCO_(3) presented minor effects on the mechanical properties of castables for its highly structural stability below 1100℃.During the slag corrosion process,SrCO_(3) and SiO_(2) in castables reacted with Al^(3+)in molten slag to form SrAl_(2)SiO_(8) phase,resulting in the increased slag viscosity and suppressed continuing penetration.

关键词： Magnesia castable SrCO_(3) Microstructure Slag resistance Mechanical property

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Rheological and mechanical properties of aluminosilicious cementitious materials as refractory castable binders

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Journal of Iron and Steel Research International 2022年第7期29卷 1145-1151页

作者： Zhong-feng Xia Chang-hao Chen Wen-hao Chi zhou-fu wang Hao Liu Yan Ma Xi-tang wang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

Metakaolin(MK)is an important refractory raw material,which has been used as a cementitious *** order to improve the bonding strength of MK,the composite cementitious materials were prepared by MK mixed with hydrat-able alumina(HA)and microsilica(MS),*** silane coupling agent(SCA)was introduced as a modifying *** rheological properties of MK-based composite cementitious slurries were *** mechanical properties of corundum castables bonded with the composite cementitious materials and calcium aluminate cement(CAC)were comparatively *** results show that SCA improves the rheological properties of MK-based composite cementitious *** slurry of MK–MS mixture flows in a plastic manner,while the slurry of MK–HA mixture presents pseudoplastic *** addition of SCA reduces the yield stress value of the MK–HA *** bonding strength of castables bonded with MK-based composite cementitious materials is lower than that of CAC bonding *** room temperature strength of MK–MS composite bonding castable remains the highest after being treated either at 1100 or 1550°C,and its high temperature modulus of rupture is higher than that of CAC bonding castables with microsilica added.

关键词： Metakaolin Hydratable alumina Microsilica Silane coupling agent Corundum castable Calcium aluminate cement

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Ligand Steric Effects on Naphthyl-α-diimine Nickel Catalyzed α-Olefin Polymerization

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Chinese Journal of Polymer Science 2018年第2期36卷 157-162页

作者： fu-zhou wang Su-Su Tian Rui-Ping Li Wei-Min Li Chang-Le Chen Advanced Catalysis and Green Manufacturing Collaborative Innovation Center School of Pertrochemical Engineering Changzhou University Chinese Academy of Sciences Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering University of Science and Technology of China

Naphthyl-α-diimine nickel complexes with systematically varied ligand sterics, activated by modified methylaluminoxane（MMAO）, were tested in the polymerization of higher α-olefin（1-hexene, 1-decene and 1-hexadecene） under suitable conditions. The polymerization results indicated the possibility of precise microstructure control, depending on catalyst structure, polymerization temperature, monomer concentration and types of monomers, which in turn strongly affects the resultant polymer properties. Naphthyl-α-diimine nickel complex bearing chiral bulky sec-phenethyl groups in the o-naphthyl position showed good catalytic activity, and resulted in branched polymers（42-88/1000 C） with high molecular weights（Mn：（4.3-15.2） × 10^4 g·mol^-1） and narrow molecular weight distribution（Mw/Mn = 1.13-1.29, RT）, which suggested a living polymerization. The increasing steric hindrance of catalyst leads to enhance insertion for 2,1-insertion of α-olefin and the chain-walking reaction.

关键词： Naphthyl-α-diimine nickel complex Chain-walking polymerization Higher α-olefin Steric effect

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Macro-microscopic dynamic characteristics of the ballast bed induced by the variation of moisture content

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Particuology 2024年第7期90卷 118-127页

作者： Shuchen wang Longlong fu Yongjia Qiu Haonan Xi Shunhua zhou Key Laboratory of Road and Traffic Engineering of the Ministry of Education Tongji UniversityShanghai 201804China Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety Tongji UniversityShanghai 201804China

Due to the excellent drainage performance of the ballast,existing studies mainly focus on the dynamic response of ballast under field capacity or *** has rarely been paid to dynamic changes in moisture content and potential *** this article,we firstly conduct a model test to determine the variation of ballast moisture content under artificial *** that,a full-scale model test with cyclic loading is carried out to study the effect of moisture content variation on the macro-microscopic response of the ballast bed,where several wireless particle sensors are installed to obtain ballast motion characteristics at strategic *** results show that the moisture content increases gradually and stabilizes at a flat peak under rainfall,despite the excellent drainage performance of ballast *** halting rainfall,the moisture content drops back to field capacity,which indicates dynamic flowing surface water on ballast particles under *** flowing surface water brings changes to the original dynamic equilibrium of ballast bed:macroscopically,the deformation rate of stabilized ballast bed increases significantly,reaching a local peak under field capacity;microscopically,the x-and z-angular accelerations of the ballast show positive correlation with rainfall *** multiscale responses indicate that field capacity is a critical moisture content.

关键词： Railway ballast Flowing surface water Wireless particle sensor Multidimensional motion full-scale model test

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Controllable Preparation of Branched Polyolefins with Various Microstructural Units via Chain-walking Ethylene and Pentene Polymerizations

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Chinese Journal of Polymer Science 2023年第6期41卷 905-914,I0008页

作者： Hong-Ju Liu Wan-Lu Tian Xiao-Yue wang Tong Lei Pei Li Guo-Yong Xu Chao Li Shao-Jie Zhang fu-zhou wang Institutes of Physical Science and Information Technology School of Computer Science and TechnologyAnhui UniversityHefei 230601China

Branched polyolefins with controllable topology structures were generated from the chain-walking(co)polymerizations of ethylene,1-pentene(1P)and 2-pentene(2P)using Brookhart-typeα-diimine Ni(II)-based catalysts possessing different para-substituted groups,{[(4-R-2-Et-6-Me-C6H2N=C)2Nap]NiBr2,Nap:1,8-naphthdiyl;R=CHMePh,Ni1;R=Ph,Ni2;R=H,Ni3}.The X-ray diffraction analysis demonstrated that the crystalline structure of Ni1′is in centrosymmetric dimer structure mode with the bimetallic Ni center connected by two bromide *** para-sec-phenethyl moiety in the catalyst Ni1 obviously improved its catalytic performance and thermal stability in the ethylene *** Ni1/Et2AlCl system showed great catalytic activities(up to 7.73×106 g·mol-1·h-1)and achieved polyethylene(PE)with alkyl chains,including Me,Et,n-Pr,n-Bu,sec-Bu branches and longer chains(Lg).Compared with the 1-pentene polymerization,this catalyst system successfully mediated the polymerization of 2P to give highly branched polymers with approximately 195 branches/1000C possessing Me,Et,and n-Pr branches and a long methylene sequence due to the monomer *** Et branches derived from 2,3-insertion is slightly less than the sum of Me and n-Pr branches derived from 3,2-insertion,indicating that the 3,2-insertion mode is a slightly favorable pathway in the polymerization of 2P.

关键词： polymerization insertion chains

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VSAN:A new visualization method for super-large-scale academic networks

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Frontiers of Computer Science 2024年第1期18卷 119-137页

作者： Qi LI Xingli wang Luoyi fu Xinde CAO Xinbing wang Jing ZHANG Chenghu zhou Department of Electronic Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Computer Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China School of Environmental Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200240China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China

As a carrier of knowledge,papers have been a popular choice since ancient times for documenting everything from major historical events to breakthroughs in science and *** the booming development of science and technology,the number of papers has been growing *** like the fact that Internet of Things(IoT)allows the world to be connected in a flatter way,how will the network formed by massive academic papers look like?Most existing visualization methods can only handle up to hundreds of thousands of node size,which is much smaller than that of academic networks which are usually composed of millions or even more *** this paper,we are thus motivated to break this scale limit and design a new visualization method particularly for super-large-scale academic networks(VSAN).Nodes can represent papers or authors while the edges means the relation(e.g.,citation,coauthorship)between *** order to comprehensively improve the visualization effect,three levels of optimization are taken into account in the whole design of VSAN in a progressive manner,i.e.,bearing scale,loading speed,and effect of layout *** main contributions are two folded:(1)We design an equivalent segmentation layout method that goes beyond the limit encountered by state-of-the-arts,thus ensuring the possibility of visually revealing the correlations of larger-scale academic entities.(2)We further propose a hierarchical slice loading approach that enables users to observe the visualized graphs of the academic network at both macroscopic and microscopic levels,with the ability to quickly zoom between different *** addition,we propose a“jumping between nebula graphs”method that connects the static pages of many academic graphs and helps users to form a more systematic and comprehensive understanding of various academic *** our methods to three academic paper citation datasets in the AceMap database confirms the visualization scalability of VSAN in t

关键词： academic networks large graph visualization graph layout graph loading

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