Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,lim...Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.展开更多
Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challen...Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challenges have been addressed thanks to the invention of a novel surface mechanical attrition treatment(SMAT)method which protects the material surface by generating a gradient-structured layer with improved strength and hardness without jeopardizing the ductility.The present work provides a comprehensive literature review on the mechanical properties of materials after SMAT including the hardness,tensile strength and elongation,and residual stress.Firstly,a brief introduction on the different forms of surface nanocrystallization is given to get a better understanding of the SMAT process and its advantages over other forms of surface treatments,and then the grain refinement mechanisms of materials by SMAT from the matrix region(base material)to the nanocrystallized layer are explained.The effects of fatigue,fracture,and wear of materials by the enhanced mechanical properties after SMAT are also discussed in detail.In addition,the various applications of SMAT ranging from automotive,photoelectric conversion,biomedical,diffusion,and 3 D-printing of materials are extensively discussed.The prospects and recent research trends in terms of mechanical properties of materials affected by SMAT are then summarized.展开更多
Over the past 30 years,additive manufacturing(AM)has developed rapidly and has demonstrated great potential in biomedical applications.AM is a materials-oriented manufacturing technology,since the solidification mecha...Over the past 30 years,additive manufacturing(AM)has developed rapidly and has demonstrated great potential in biomedical applications.AM is a materials-oriented manufacturing technology,since the solidification mechanism,architecture resolution,post-treatment process,and functional application are based on the materials to be printed.However,3D printable materials are still quite limited for the fabrication of bioimplants.In this work.2D/3D AM materials for bioimplants are reviewed.Furthermore,inspired by Tai Chi,a simple yet novel soft/rigid hybrid 4D AM concept is advanced to develop complex and dynamic biological structures in the human body based on 4D printing hybrid ceramic precursor/ceramic materials that were previously developed by our group.With the development of multi-material printing technology,the development of bioimplants and soft/rigid hybrid biological structures with 2D/3D/4D AM materials can be anticipated.展开更多
Electric-spark deposition (ESD) was adopted for depositing a Ti( CN) -based ceramic coating on the TC4 titanium alloy substrate using a laboratory-developed electric-spark deposition system, a nitrogen-sealed atmo...Electric-spark deposition (ESD) was adopted for depositing a Ti( CN) -based ceramic coating on the TC4 titanium alloy substrate using a laboratory-developed electric-spark deposition system, a nitrogen-sealed atmosphere and graphite electrode. The surface morphology, microstructure, interfacial behavior between the coatings and substrate, phase and element composition of the coatings were investigated by scanning electron microscope ( SEM ) , X-ray diffraction ( XRD ) , X-ray photoelectron spectroscopy ( XPS ) and Auger electron spectroscopy ( AES ) . Microhardness profile was measured with a Vickers microhardness tester. The results show that metallurgical bond between the coating and substrate is realized and the phase of coatings are made up of Ti( CN ) spherocrystal and dendritic crystal, TiV and C. Ti( CN) ceramic particles, which is in-situ synthesized by the reaction among titanium from the substrate, carbon from the graphite electrode and nitrogen from the shielding nitrogen gas, is about 600 mn and distributes dispersively among the coatings. Microharduess profile falls off with the coatings thickness increasing and the highest microhardness values of the superficial coating could be up to 1 496HV, which is six times more than that of the substrate.展开更多
Dual-phase metallic glasses(DP-MGs),a special member of the MGs family,often reveal unusual strength and ductility,yet,their corrosion behaviors are not understood.Here,we developed a nanostructured Mg_(57)Zn_(36)Ca_(...Dual-phase metallic glasses(DP-MGs),a special member of the MGs family,often reveal unusual strength and ductility,yet,their corrosion behaviors are not understood.Here,we developed a nanostructured Mg_(57)Zn_(36)Ca_(7)(at.%)DP-MG and uncovered its corrosion mechanism in simulated body fluid(SBF)at the near-atomic scale utilizing transmission electron microscope(TEM)and atom probe tomography(APT).The 10-nm-wide Ca-rich amorphous phases allow oxygen propagation into the DP-MG,resulting in a micrometer thick hydroxides/oxides layer.This dense corrosion layer protects the DP-MG from further corrosion,enabling a corrosion rate that is 77%lower than that of Mg(99.99%purity).展开更多
The effect of mischmetal addition on lead segregation in high lead bronze(grade ZQPb25-5)is studied in this paper.The testing results confirm that 0.5 to 1.0% misehmetal addition can effectively prevent lead from grav...The effect of mischmetal addition on lead segregation in high lead bronze(grade ZQPb25-5)is studied in this paper.The testing results confirm that 0.5 to 1.0% misehmetal addition can effectively prevent lead from gravity and inverse segregation.The results of preventing lead from segregation respectively by mischmetal and nickel are also compared in the paper.The mischmetal addition in high lead bronze is distributed in the copper matrix mainly in the form of a compound which promotes early precipitation and refinement of α-dendrites, thus restraining the Pb-rich melt from either sinking to the bottom or escaping to the surface layer of the casting.As a result,the tendency of lead segregation is significantly decreased.Proper addition of mischmetal can also improve the mechanical properties,especially the ductility of high lead bronze.In addition,the contents of tin in high lead bronze can partially be substituted by mischmetal addition.展开更多
In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phas...In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phase of metal-containing nanomaterials could significantly affect their properties and functions.In particular,nanomaterials with amorphous phase,which possess long-range disordered atomic arrangements,and the amorphous/crystalline heterophase nanostructures comprised of both amorphous and crystalline phases,have exhibited superior performance in various applications,e.g.,catalysis and energy storage.In this review,a brief overview of the recent progress on the wet-chemical synthesis and applications of amorphous and amorphous/crystalline heterophase metal-containing nanomaterials has been provided.Subsequently,on the basis of different categories of metal-containing nanomaterials,including metals,metal alloys,and metal compounds,their synthetic routes and promising applications will be highlighted.Finally,current challenges and some personal perspectives in this emerging research field will be proposed.展开更多
Temperature has an important impact on the corrosion resistance of mold with cooling channels prepared by casting method.The effect of preheating temperature of the mold and the carbon fiber core on the roughness and ...Temperature has an important impact on the corrosion resistance of mold with cooling channels prepared by casting method.The effect of preheating temperature of the mold and the carbon fiber core on the roughness and corrosion resistance of U-shaped cooling channels made of Al-12Si alloy was examined in depth.The experimental results suggest that as the preheating temperature increased from 273 K to 573 K,the roughness of the inner wall of the cooling channel reduced from 96.6μm to 77.0μm.When the preheating temperature continued to increase to 723 K,the roughness increased to 85.3μm.The wetting between the Al melt and the carbon fiber will reduce micro bubbles and waves on the channel wall as the preheating temperature rises,thereby reducing the roughness.However,with the further increase of preheating temperature,it will increase the solidification time of the Al melt.At this time,the carbon fiber and Al melt will take more time to react,which increases the roughness of the channel wall to a certain extent.The results of exfoliation corrosion show that the larger roughness will aggravate exfoliation corrosion.The prolongation of high temperature reaction time between the carbon fiber and the Al melt will lead to the segregation of Si,which is easy to cause intergranular corrosion.Therefore,reasonable preheating temperature has an important impact on the roughness and corrosion resistance of U-shaped cooling channels.展开更多
Repair welding of AA 6082-T6 joints was carried out using ER 4043 filler through the TIG welding process with or without pulsed current.Microstructure and mechanical characteristics of the joints before and after repa...Repair welding of AA 6082-T6 joints was carried out using ER 4043 filler through the TIG welding process with or without pulsed current.Microstructure and mechanical characteristics of the joints before and after repairing were investigated by examining macrostructure,microstructure,and distributions of porosity in the weld metal(WM),and by hardness,tensile,and bending tests.We observed that the welding current,phase transformations in heat-affected zone(HAZ)and porosity introduced in the WM during welding influence on its mechanical properties in sequence.The experimental results showed that the bead width and penetration as well as size of pores in the joints were mainly influenced by the welding currents.The sound joints were obtained at a welding current of 140 A with or without pulsed current when welding speed and gas flow rate were set at 20 cm·min-1 and 15 L·min-1,respectively.Among them,the decrease in mechanical properties of repair weld(RW)was directly related to the phase transformations in the over-ageing zone due to the double welding thermal cycles and elevated distribution of porosity in the WM.In addition,it was observed that the comparatively smaller grain size and lower porosity in WM of the RW produced by pulsed TIG welding gave a positive effect on its mechanical properties.展开更多
Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion technique.Large-scale electrolysis of freshwater may deplete water resources and cause water scarcity worldwide.Thus,...Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion technique.Large-scale electrolysis of freshwater may deplete water resources and cause water scarcity worldwide.Thus,seawater electrolysis is a potential solution to the future energy and water crisis.In seawater electrolysis,it is critical to develop cost-effective electrocatalysts to split seawater without chloride corrosion.Herein,we present zinc-doped nickel iron(oxy)hydroxide nanocubes passivated by negatively charged polyanions(NFZ-PBA-S)that exhibits outstanding catalytic activity,stability,and selectivity for seawater oxidation.Zn dopants and polyanion-rich passivated surface layers in NFZ-PBA-S could effectively repel chlorine ions and enhance corrosion resistance,enabling its excellent catalytic activity and stability for seawater oxidation.展开更多
Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly im...Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly improve their catalytic activity,it often involves in-plane modulation and requires high temperatures.Herein,we report a novel strategy to manipulate the local electronic structure of SACs via the modulation of axial Co-S bond anchored onto graphitic carbon nitride(C_(3)N_(4))at room temperature(RT).Each Co atom is bonded to four N atoms and one S atom(Co-(N,S)/C_(3)N_(4)).Owing to the greater electronegativity of S in the Co-S bond,the local electronic structure of the Co atoms is available to be controlled at a relatively moderate level.Consequently,when employed for the photocatalytic hydrogen evolution reaction,the adsorption energy of intermediate hydrogen(H*)on the Co atoms is remarkably low.In the presence of the Co-(N,S)/C_(3)N_(4)SACs,the hydrogen evolution rates reach up to 10 mmol/(g·h),which is nearly 10 and 2.5 times greater than the rates in the presence of previously reported transition metal/C_(3)N_(4)and noble platinum nanoparticles(PtNPs)/C_(3)N_(4)catalysts,respectively.Attributed to the tailorable axial Co-S bond in the SAC,the local electronic structure of the Co atoms can be further optimized for other photocatalytic reactions.This axial coordination engineering strategy is universal in catalyst designing and can be used for a variety of photocatalytic applications.展开更多
The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical co...The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high(20-63 V) voltages.展开更多
The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitut...The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitutive theory([1]) and B-L planar anisotropy yield criterion([2]). Simulated results are compared with experimental ones. Very good consistence is obtained between numerical and experimental results. The relationship between the anisotropy coefficient R and the shear band angle theta is found.展开更多
The electrochemical CO_(2) reduction reaction(CO_(2)RR)offers a green and sustainable process to convert CO_(2) into valuable chemical stocks and fuels.Metal is one of the most promising types of catalysts to drive an...The electrochemical CO_(2) reduction reaction(CO_(2)RR)offers a green and sustainable process to convert CO_(2) into valuable chemical stocks and fuels.Metal is one of the most promising types of catalysts to drive an efficient and selective CO_(2)RR.The catalytic performance of metal nanocatalysts is strongly dependent on their structural features.Recently,phase engineering of nanomaterials(PEN)has emerged as a prominent tactic to regulate the catalytic performance of metal nanocatalysts for the CO_(2)RR.A broad range of metal nanocatalysts with conventional and unconventional crystal phases has been developed,and remarkable achievements have been made.This review summarizes the most recent developments in phase engineering of metal nanocatalysts for the electrochemical CO_(2)RR.We first introduce the different crystal phases of metal nanocatalysts used in the CO_(2)RR and then discuss various synthetic strategies for unconventional phases of metal nanocatalysts.After that,detailed discussions of metal nanocatalysts with conventional and unconventional phases,including amorphous phases,are presented.Finally,the challenges and perspectives in this emerging area are discussed.展开更多
The aim of this paper is to report the results of experiments carried out on Al-Cu alloys with different Cu contents,studying the microstructure evolution during holding in the semi-solid state.The 3-D microstructure ...The aim of this paper is to report the results of experiments carried out on Al-Cu alloys with different Cu contents,studying the microstructure evolution during holding in the semi-solid state.The 3-D microstructure was observed by in situ X-ray microtomography carried out at ESRF Grenoble,France.The variation of the solid-liquid interface area per unit volume during holding was determined.In addition,local observations show that two coarsening mechanisms of the solid particles occur simultaneously:dissolution of small particles to the benefit of larger ones by an Ostwald-type mechanism and the growth of necks between solid particles due to coalescence.These observations confirm that in situ X-ray tomography is a very powerful tool to study the microstructure evolution in the semi-solid state and the influencing mechanisms in real-time.展开更多
基金support provided by the Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project(HZQB-KCZYB-2020030)the Research Grants Council of Hong Kong(Project No:AoE/M-402/20.)+1 种基金the Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050248)the Hong Kong Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Center.
文摘Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.
基金supports of the National Key R&D Program of China(Project No.2017YFA0204403)Hong Kong Themebased Research Scheme Ref.(T13-402/17-N).
文摘Most of the challenges experienced by many engineering materials originate from the surface which later leads to total failure,hence affecting the resultant mechanical properties and service life.However,these challenges have been addressed thanks to the invention of a novel surface mechanical attrition treatment(SMAT)method which protects the material surface by generating a gradient-structured layer with improved strength and hardness without jeopardizing the ductility.The present work provides a comprehensive literature review on the mechanical properties of materials after SMAT including the hardness,tensile strength and elongation,and residual stress.Firstly,a brief introduction on the different forms of surface nanocrystallization is given to get a better understanding of the SMAT process and its advantages over other forms of surface treatments,and then the grain refinement mechanisms of materials by SMAT from the matrix region(base material)to the nanocrystallized layer are explained.The effects of fatigue,fracture,and wear of materials by the enhanced mechanical properties after SMAT are also discussed in detail.In addition,the various applications of SMAT ranging from automotive,photoelectric conversion,biomedical,diffusion,and 3 D-printing of materials are extensively discussed.The prospects and recent research trends in terms of mechanical properties of materials affected by SMAT are then summarized.
基金This work was supported by the National Key R&D Program of China(2017YFA0204403)the Major Program of the National Natural Science Foundation of China(51590892)+3 种基金the General Research Fund Research Grants Council(Hong Kong)(CityU 11209918)the Hong Kong Collaborative Research Fund Scheme(C4026-17W)the Hong Kong Theme-based Research Scheme(T13-402/17-N)the Shenzhen-Hong Kong cooperation zone for technology and innovation(HZQB-KCZYB-2020030).
文摘Over the past 30 years,additive manufacturing(AM)has developed rapidly and has demonstrated great potential in biomedical applications.AM is a materials-oriented manufacturing technology,since the solidification mechanism,architecture resolution,post-treatment process,and functional application are based on the materials to be printed.However,3D printable materials are still quite limited for the fabrication of bioimplants.In this work.2D/3D AM materials for bioimplants are reviewed.Furthermore,inspired by Tai Chi,a simple yet novel soft/rigid hybrid 4D AM concept is advanced to develop complex and dynamic biological structures in the human body based on 4D printing hybrid ceramic precursor/ceramic materials that were previously developed by our group.With the development of multi-material printing technology,the development of bioimplants and soft/rigid hybrid biological structures with 2D/3D/4D AM materials can be anticipated.
基金The work was supported by the Natural Science Foundation of Hebei Province of China under Grant No. E2007000566.
文摘Electric-spark deposition (ESD) was adopted for depositing a Ti( CN) -based ceramic coating on the TC4 titanium alloy substrate using a laboratory-developed electric-spark deposition system, a nitrogen-sealed atmosphere and graphite electrode. The surface morphology, microstructure, interfacial behavior between the coatings and substrate, phase and element composition of the coatings were investigated by scanning electron microscope ( SEM ) , X-ray diffraction ( XRD ) , X-ray photoelectron spectroscopy ( XPS ) and Auger electron spectroscopy ( AES ) . Microhardness profile was measured with a Vickers microhardness tester. The results show that metallurgical bond between the coating and substrate is realized and the phase of coatings are made up of Ti( CN ) spherocrystal and dendritic crystal, TiV and C. Ti( CN) ceramic particles, which is in-situ synthesized by the reaction among titanium from the substrate, carbon from the graphite electrode and nitrogen from the shielding nitrogen gas, is about 600 mn and distributes dispersively among the coatings. Microharduess profile falls off with the coatings thickness increasing and the highest microhardness values of the superficial coating could be up to 1 496HV, which is six times more than that of the substrate.
基金partially supported by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030Hong Kong Research Grants Council Collaborative Research Fund(Ref.C4026-17 W)+2 种基金Theme-based Research Scheme(Ref.T13402/17-N)funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 958457supported by the City U grant 9360161 and CRF grant C1027-14E。
文摘Dual-phase metallic glasses(DP-MGs),a special member of the MGs family,often reveal unusual strength and ductility,yet,their corrosion behaviors are not understood.Here,we developed a nanostructured Mg_(57)Zn_(36)Ca_(7)(at.%)DP-MG and uncovered its corrosion mechanism in simulated body fluid(SBF)at the near-atomic scale utilizing transmission electron microscope(TEM)and atom probe tomography(APT).The 10-nm-wide Ca-rich amorphous phases allow oxygen propagation into the DP-MG,resulting in a micrometer thick hydroxides/oxides layer.This dense corrosion layer protects the DP-MG from further corrosion,enabling a corrosion rate that is 77%lower than that of Mg(99.99%purity).
文摘The effect of mischmetal addition on lead segregation in high lead bronze(grade ZQPb25-5)is studied in this paper.The testing results confirm that 0.5 to 1.0% misehmetal addition can effectively prevent lead from gravity and inverse segregation.The results of preventing lead from segregation respectively by mischmetal and nickel are also compared in the paper.The mischmetal addition in high lead bronze is distributed in the copper matrix mainly in the form of a compound which promotes early precipitation and refinement of α-dendrites, thus restraining the Pb-rich melt from either sinking to the bottom or escaping to the surface layer of the casting.As a result,the tendency of lead segregation is significantly decreased.Proper addition of mischmetal can also improve the mechanical properties,especially the ductility of high lead bronze.In addition,the contents of tin in high lead bronze can partially be substituted by mischmetal addition.
基金supported by the grants(Nos.9610478,9680314,7020013,and 1886921)the Start-Up Grant(No.9380100),ITC via the Hong Kong Branch of the National Precious Metals Material Engineering Research Center(NPMM)from City University of Hong Kong,the Research Grants Council of Hong Kong,China(No.AoE/P-701/20)the Science Technology and Innovation Committee of Shenzhen Municipality(Nos.JCYJ20200109143412311 and SGDX2020110309300301,“Preparation of single atoms on transition metal chalcogenides for electrolytic hydrogen evolution”,CityU).
文摘In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phase of metal-containing nanomaterials could significantly affect their properties and functions.In particular,nanomaterials with amorphous phase,which possess long-range disordered atomic arrangements,and the amorphous/crystalline heterophase nanostructures comprised of both amorphous and crystalline phases,have exhibited superior performance in various applications,e.g.,catalysis and energy storage.In this review,a brief overview of the recent progress on the wet-chemical synthesis and applications of amorphous and amorphous/crystalline heterophase metal-containing nanomaterials has been provided.Subsequently,on the basis of different categories of metal-containing nanomaterials,including metals,metal alloys,and metal compounds,their synthetic routes and promising applications will be highlighted.Finally,current challenges and some personal perspectives in this emerging research field will be proposed.
基金financially supported by the National Natural Science Foundation of China(No.51775353)the National Key Research and Development Program of China(No.2019YFB2006501)+2 种基金the Program for Natural Science Foundation of Liaoning Province(No.2021-BS-150)Science and Technology Program of Liaoning Provincial Department of Education(LJKZ0116)Hebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(HKDEFM2021204)。
文摘Temperature has an important impact on the corrosion resistance of mold with cooling channels prepared by casting method.The effect of preheating temperature of the mold and the carbon fiber core on the roughness and corrosion resistance of U-shaped cooling channels made of Al-12Si alloy was examined in depth.The experimental results suggest that as the preheating temperature increased from 273 K to 573 K,the roughness of the inner wall of the cooling channel reduced from 96.6μm to 77.0μm.When the preheating temperature continued to increase to 723 K,the roughness increased to 85.3μm.The wetting between the Al melt and the carbon fiber will reduce micro bubbles and waves on the channel wall as the preheating temperature rises,thereby reducing the roughness.However,with the further increase of preheating temperature,it will increase the solidification time of the Al melt.At this time,the carbon fiber and Al melt will take more time to react,which increases the roughness of the channel wall to a certain extent.The results of exfoliation corrosion show that the larger roughness will aggravate exfoliation corrosion.The prolongation of high temperature reaction time between the carbon fiber and the Al melt will lead to the segregation of Si,which is easy to cause intergranular corrosion.Therefore,reasonable preheating temperature has an important impact on the roughness and corrosion resistance of U-shaped cooling channels.
基金Funded by the Center of Excellence in Metals and Materials Engineering(CEMME),Faculty of Engineering,Prince of Songkla UniversitySupported by the National Science,Research and Innovation Fund(NSRF)and Prince of Songkla University(No.ENG6505079S)。
文摘Repair welding of AA 6082-T6 joints was carried out using ER 4043 filler through the TIG welding process with or without pulsed current.Microstructure and mechanical characteristics of the joints before and after repairing were investigated by examining macrostructure,microstructure,and distributions of porosity in the weld metal(WM),and by hardness,tensile,and bending tests.We observed that the welding current,phase transformations in heat-affected zone(HAZ)and porosity introduced in the WM during welding influence on its mechanical properties in sequence.The experimental results showed that the bead width and penetration as well as size of pores in the joints were mainly influenced by the welding currents.The sound joints were obtained at a welding current of 140 A with or without pulsed current when welding speed and gas flow rate were set at 20 cm·min-1 and 15 L·min-1,respectively.Among them,the decrease in mechanical properties of repair weld(RW)was directly related to the phase transformations in the over-ageing zone due to the double welding thermal cycles and elevated distribution of porosity in the WM.In addition,it was observed that the comparatively smaller grain size and lower porosity in WM of the RW produced by pulsed TIG welding gave a positive effect on its mechanical properties.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Science,ICT and Future Planning (2021R1A2C2091497 and 2022R1A2C2010162)supported by“Regional Innovation Strategy (RIS)”through the National Research Foundation of Korea (NRF)funded by the Ministry of Education (MOE) (2022RIS-005)+1 种基金supported by the Ministry of Trade,Industry,and Energy (20018145)supported by KIST Institutional Program (Project Nos.2V09781)。
文摘Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion technique.Large-scale electrolysis of freshwater may deplete water resources and cause water scarcity worldwide.Thus,seawater electrolysis is a potential solution to the future energy and water crisis.In seawater electrolysis,it is critical to develop cost-effective electrocatalysts to split seawater without chloride corrosion.Herein,we present zinc-doped nickel iron(oxy)hydroxide nanocubes passivated by negatively charged polyanions(NFZ-PBA-S)that exhibits outstanding catalytic activity,stability,and selectivity for seawater oxidation.Zn dopants and polyanion-rich passivated surface layers in NFZ-PBA-S could effectively repel chlorine ions and enhance corrosion resistance,enabling its excellent catalytic activity and stability for seawater oxidation.
基金National Natural Science Foundation of China(No.22008251)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515010318)Shenzhen Science and Technology Program(No.JCYJ20220531095813031).
文摘Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly improve their catalytic activity,it often involves in-plane modulation and requires high temperatures.Herein,we report a novel strategy to manipulate the local electronic structure of SACs via the modulation of axial Co-S bond anchored onto graphitic carbon nitride(C_(3)N_(4))at room temperature(RT).Each Co atom is bonded to four N atoms and one S atom(Co-(N,S)/C_(3)N_(4)).Owing to the greater electronegativity of S in the Co-S bond,the local electronic structure of the Co atoms is available to be controlled at a relatively moderate level.Consequently,when employed for the photocatalytic hydrogen evolution reaction,the adsorption energy of intermediate hydrogen(H*)on the Co atoms is remarkably low.In the presence of the Co-(N,S)/C_(3)N_(4)SACs,the hydrogen evolution rates reach up to 10 mmol/(g·h),which is nearly 10 and 2.5 times greater than the rates in the presence of previously reported transition metal/C_(3)N_(4)and noble platinum nanoparticles(PtNPs)/C_(3)N_(4)catalysts,respectively.Attributed to the tailorable axial Co-S bond in the SAC,the local electronic structure of the Co atoms can be further optimized for other photocatalytic reactions.This axial coordination engineering strategy is universal in catalyst designing and can be used for a variety of photocatalytic applications.
文摘The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high(20-63 V) voltages.
基金The project supported by the National Natural Science Foundation of China and the Excellent Youth Teacher Foundation of the State Education Commission of China
文摘The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitutive theory([1]) and B-L planar anisotropy yield criterion([2]). Simulated results are compared with experimental ones. Very good consistence is obtained between numerical and experimental results. The relationship between the anisotropy coefficient R and the shear band angle theta is found.
基金support from the Start-up Fund(BDC2)and Research Institute for Advanced Manufacturing(RIAM)Fund(CD4D)from the Hong Kong Polytechnic University.Y.C.thanks the support from Start-up Fund(Project No.4930977)the Direct Grant for Research(Project No.4053444)from the Chinese University of Hong Kong+3 种基金H.Z.thanks the support from ITC via the Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM),the Research Grants Council of Hong Kong(GRF Project No.11301721)the Start-Up Grant(Project No.9380100)the grants(Project Nos.7020054,9678272,and 1886921)from the City University of Hong Kongthe Science Technology and Innovation Committee of Shenzhen Municipality(“Preparation of single atoms on transition metal chalcogenides for electrolytic hydrogen evolution”,CityU),and the Project 52131301 supported by NSFC.
文摘The electrochemical CO_(2) reduction reaction(CO_(2)RR)offers a green and sustainable process to convert CO_(2) into valuable chemical stocks and fuels.Metal is one of the most promising types of catalysts to drive an efficient and selective CO_(2)RR.The catalytic performance of metal nanocatalysts is strongly dependent on their structural features.Recently,phase engineering of nanomaterials(PEN)has emerged as a prominent tactic to regulate the catalytic performance of metal nanocatalysts for the CO_(2)RR.A broad range of metal nanocatalysts with conventional and unconventional crystal phases has been developed,and remarkable achievements have been made.This review summarizes the most recent developments in phase engineering of metal nanocatalysts for the electrochemical CO_(2)RR.We first introduce the different crystal phases of metal nanocatalysts used in the CO_(2)RR and then discuss various synthetic strategies for unconventional phases of metal nanocatalysts.After that,detailed discussions of metal nanocatalysts with conventional and unconventional phases,including amorphous phases,are presented.Finally,the challenges and perspectives in this emerging area are discussed.
基金project ANR-05-BLAN-0286-01 TOMOSOLIDAL supported by the French Agence Nationale de la Recherche,which is gratefully acknowledged
文摘The aim of this paper is to report the results of experiments carried out on Al-Cu alloys with different Cu contents,studying the microstructure evolution during holding in the semi-solid state.The 3-D microstructure was observed by in situ X-ray microtomography carried out at ESRF Grenoble,France.The variation of the solid-liquid interface area per unit volume during holding was determined.In addition,local observations show that two coarsening mechanisms of the solid particles occur simultaneously:dissolution of small particles to the benefit of larger ones by an Ostwald-type mechanism and the growth of necks between solid particles due to coalescence.These observations confirm that in situ X-ray tomography is a very powerful tool to study the microstructure evolution in the semi-solid state and the influencing mechanisms in real-time.