Aqueous zinc(Zn)-ion batteries(ZIBs)have garnered significant attention as promising energy storage devices,primarily due to their low cost,high power density,and excellent safety profile.However,the commercial viabil...Aqueous zinc(Zn)-ion batteries(ZIBs)have garnered significant attention as promising energy storage devices,primarily due to their low cost,high power density,and excellent safety profile.However,the commercial viability of these batteries is hindered by several issues related to the Zn metal anode,including dendritic growth,hydrogen evolution reaction(HER),surface corrosion,and passivation.This review delves into the root causes and key factors influencing these challenges from both electrochemical thermodynamics and kinetics perspectives.Subsequently,viable strategies to mitigate these issues are systematically summarized,including Zn anode reconstruction,artificial solid-electrolyte interphase(SEI)protection,electrolyte formulation optimization,and separator functionalization.Recent research advancements are examined thoroughly,with a focus on the mechanisms behind these approaches and the resulting battery performance.The review also critically assesses the strengths and limitations of these solutions.Finally,we highlight crucial research directions aimed at advancing the practical application of Zn metal anodes in future aqueous ZIBs.展开更多
Flexible transparent antennas(FTAs)are widely used in wireless transmission fields,and their technological iterations are accelerating.However,the high losses caused by materials and structures limit the development o...Flexible transparent antennas(FTAs)are widely used in wireless transmission fields,and their technological iterations are accelerating.However,the high losses caused by materials and structures limit the development of FTAs with both high light transmission and high gain,and the rapid iteration rate demands greater process flexibility,which makes it difficult for existing technologies to achieve both demands.Here,we design a novel shell-core structure composite metal mesh(CMM)FTA to achieve extremely low skin depth loss and ohmic loss using skin effect and report a novel hybrid additive manufacturing method based on electric field oriented deposition to achieve efficient and flexible manufacturing of the unique Ag/Cu core-shell structure CMM FTA.The typical sample has a light transmittance of 80%(including substrate)when the sheet resistance is 0.29Ω·sq^(-1),and has excellent bending and torsion resistance.The peak gain in the working band is as high as 5.22 dB,and the efficiency is 80%,which is close to the performance of the opaque Cu patch antenna.It also realizes smooth and stable real-time wireless transmission under bending and long-distance conditions.This method addresses the shortcomings of FTAs,namely their high cost,low manufacturing efficiency,and low performance,especially in the rapid iterative development of antennas.展开更多
It is commonly recognized that the cooling rate has a substantial effect on solute partitioning and its resultant microsegregation during solidification.The classical dendrite tip undercooling theory clarifies the mit...It is commonly recognized that the cooling rate has a substantial effect on solute partitioning and its resultant microsegregation during solidification.The classical dendrite tip undercooling theory clarifies the mitigation of microsegregation by increasing the cooling rate.However,most of the studies focused on binary alloys,leaving an open question as to whether the microsegregation of different solutes in a multi-component alloy system exhibits a relieving degree similar to increasing cooling rate.Taking a widely used 6022-type Al alloy(Al-0.76Mg-0.93Si-0.2Fe)as a model alloy,the current study reveals that the microsegregation of Mg gets alleviated to the greatest extent,followed by those of Si and Fe when the cooling rate increases from 5 to 128 K/s.This phenomenon is attributed to the solute-based difference in response to partitioning to cooling rate(denoted as Rk).We propose a theoretical equation to quantify Rk,and the R_(k)values of solute Mg,Si,and Fe successfully explain the rank of solute partitioning in exper-iments.Furthermore,a broad range of R_(k)values of other commonly used alloying elements in Al alloys were calculated and ranked,delivering a handy tool to predict the microsegregation behavior and sol-ubility of different solute elements upon sub-rapid solidification,which is consistent with experimental observation.This framework can also be extended to other multi-component alloy systems.展开更多
Arbitrary and high-precision thermal patterning has long been desired in the field of thermal functional materials.However,existing thermal patterning strategies have not been widely applied,either hampered by the dif...Arbitrary and high-precision thermal patterning has long been desired in the field of thermal functional materials.However,existing thermal patterning strategies have not been widely applied,either hampered by the difficulty in fabricating anisotropic metamaterials or limited by complex thermal manipulation.We propose an on-demand thermal patterning scheme that sandwiches geometrically engineered heating arrays between a substrate and an encapsulation layer to form composite structures and control the omnidirectional transfer of the heat flux gen-erated by the heating arrays.These heating arrays are digitally assembled from multiple heater cells of varying widths and continuously printed using electric-field-driven 3D printing.A design strategy for thermal patterning with good uniformity within individual regions and high contrast between regions is proposed.The performance of the on-demand thermal patterning is verified via high-precision thermal printing.The proposed scheme pro-vides a general and reproducible method for designing thermal functional materials,with potential applications in thermochromics,messaging,thermal camouflage,and illusions.展开更多
Specially shaped permanent magnet structures can satisfy the requirements of equipment with limited space or unique shapes.Thereby,these optimize the distribution of magnetic fields.However,traditional manufacturing m...Specially shaped permanent magnet structures can satisfy the requirements of equipment with limited space or unique shapes.Thereby,these optimize the distribution of magnetic fields.However,traditional manufacturing methods are limited by the mold design and insufficient material utilization.In this study,a polymer-based Nd_(2)Fe_(14)B(NdFeB)magnetic slurry was developed based on direct ink writing(DIW)3D printing technology.A rapidly volatilizable magnetic slurry was used to achieve 3D oriented controllable layering,thus realizing the direct molding fabrication of NdFeB permanent magnets with complex structures.By exploring and optimizing the 3D printing process parameters,specially shaped bonded NdFeB permanent magnet structures with high precision and shape fidelity were prepared.The test results indicated that the remnant magnetization of the printed magnets was proportional to the NdFeB content in the slurry,the coercivity closely matched that of the original powder,and the mechanical properties of the printed magnets were favorable.Building on this,a magnetically driven helical-structure robot was designed and printed to achieve stable motion in low-Reynolds-number fluids.This paper presents a new,low-cost solution for the room-temperature preparation of shape-bonded NdFeB permanent magnets.展开更多
Electrohydrodynamic(EHD)jet printing is a promising method for high-resolution manufacturing;however,it often suffers from jet deflection owing to the accumulation of residual charges within printed structures.These r...Electrohydrodynamic(EHD)jet printing is a promising method for high-resolution manufacturing;however,it often suffers from jet deflection owing to the accumulation of residual charges within printed structures.These residual charges lead to jet deflection.This study introduces a novel noncontact electric field-driven(NEFD)jet micro 3D printing technique to address these challenges.By decoupling the high-voltage power supply from both the printing material and substrate,NEFD jet micro 3D printing eliminates the pathway for charge injection into the printing material,reducing residual charges by a factor of five or more compared to EHD jet printing.Our research revealed an inherent attractive force between the material jet and previously deposited material,regardless of the material used.Furthermore,we demonstrate that employing a pre-defined allowance printing strategy during fabrication reduces the standard deviation of actual fiber spacing values from 11.4μm to 1.5μm,thereby improving the fiber spacing consistency.This enhanced control enabled the successful fabrication of line patterns with 20±1μm fiber diameters and 61.1±1.9μm fiber spacing,demonstrating the feasibility of NEFD jet micro 3D printing.This technique offers a novel solution for mitigating the challenges associated with electric fields and charge accumulation in EHD jet printing,paving the way for enhanced resolution and material compatibility in micro-/nanoscale additive manufacturing.展开更多
Electrohydrodynamic(EHD)jet printing represents a novel micro/nano-scale additive manufacturing process that utilises a high-voltage induced electric field between the nozzle and the substrate to print micro/nanoscale...Electrohydrodynamic(EHD)jet printing represents a novel micro/nano-scale additive manufacturing process that utilises a high-voltage induced electric field between the nozzle and the substrate to print micro/nanoscale structures.EHD printing is particularly advantageous for the fabrication on flexible or non-flat substrates and of large aspect ratio micro/nanostructures and composite multi-material structures.Despite this,EHD printing has yet to be fully industrialised due to its low throughput,which is primarily caused by the limitations of serial additive printing technology.The parallel multi-nozzle array-based process has become the most promising option for EHD printing to achieve large-scale printing by increasing the number of nozzles to realise multichannel parallel printing.This paper reviews the recent development of multi-nozzle EHD printing technology,analyses jet motion with multi-nozzle,explains the origins of the electric field crosstalk effect under multi-nozzle and discusses several widely used methods for overcoming it.This work also summarises the impact of different process parameters on multi-nozzle EHD printing and describes the current manufacturing process using multi-nozzle as well as the method by which they can be realised independently.In addition,it presents an additional significant utilisation of multi-nozzle printing aside from enhancing single-nozzle production efficiency,which is the production of composite phase change materials through multi-nozzle.Finally,the future direction of multi-nozzle EHD printing development is discussed and envisioned.展开更多
Increasingly harsh service conditions place higher requirements for the high strain-rate performance of titanium alloys.Adiabatic shear band(ASB),a phenomenon prone to dynamic loading,is often accom-panied by catastro...Increasingly harsh service conditions place higher requirements for the high strain-rate performance of titanium alloys.Adiabatic shear band(ASB),a phenomenon prone to dynamic loading,is often accom-panied by catastrophic damage.Yet,it is unclear how the internal nanostructures are related to shear instability.Here we report detailed microstructural evolution in the ASB of a titanium alloy via in-depth focused ion beam(FIB),transmission Kikuchi diffraction(TKD),and high-resolution transmission electron microscope(HRTEM)analyses,with the deformation instability phenomenon discussed from the energy perspective.The ASB interior undergoes multifaceted changes,namely deformation-induced beta-to-alpha transformation and deformation-induced martensitic transformation to form substantially refined and heterogeneous structures.Meanwhile,two types of extremely fine twins are identified to occur within both nano-sized martensite and alpha phase.The critical plastic work representing the onset of adiabatic shear instability and dynamic equilibrium is observed to be constant for a specific structure in the same deformation mode.The energy analysis could be extended to other materials subjected to high strain-rate dynamic deformation.展开更多
Nitrogen processed, cold sprayed commercially pure(CP)-Al coatings on Mg-based alloys mostly lack acceptable hardness, wear resistance and most importantly are highly susceptible to localized corrosion in chloride con...Nitrogen processed, cold sprayed commercially pure(CP)-Al coatings on Mg-based alloys mostly lack acceptable hardness, wear resistance and most importantly are highly susceptible to localized corrosion in chloride containing solutions. In this research, commercially pure α-Ti top coating having good pitting potential(~1293 mV_(SCE)), high microhardness(HV_(0.025): 263.03) and low wear rate was applied on a CP-Al coated Mg-based alloy using high pressure cold spray technology. Potentiodynamic polarization(PDP) curves indicated that the probability of transition from metastable pits to the stable pits for cold spayed(CS) Al coating is considerably higher compared to that with the CS Ti top coating(for Ti/Al/Mg system). In addition, CS Ti top coating was in the passivation region in most pH ranges even after 48 h immersion in 3.5 wt% NaCl solution. The stored energy in the CS Ti top coating(as a passive metal) was presumed to be responsible for the easy passivation. Immersion tests indicated no obvious pits formation on the intact CS Ti top coating surface and revealed effective corrosion protection performance of the CS double layered noble barrier coatings on Mg alloys in 3.5 wt% NaCl solution even after 264 h.展开更多
The mechanical properties of as-cast metallic materials depend strongly on the size and shape of grains,which are critical microstructural parameters dictated by the interplay of nucleation and growth of crys-talline ...The mechanical properties of as-cast metallic materials depend strongly on the size and shape of grains,which are critical microstructural parameters dictated by the interplay of nucleation and growth of crys-talline solids during solidification.In our experiments,the microstructure transition from coarse colum-nar crystals into fine equiaxed crystals for dilute Al-Mn-Si alloys was achieved by using sub-rapid so-lidification with the addition of Al-5Ti-1B grain refiner.The average grain size of Al alloy was reduced from a millimeter size to 73μm.Through temperature gradient calculation,we found that the acqui-sition of fine equiaxed crystals could be attributed to the existence of a high number density of TiB2,acting as effective nucleation sites with an increase in total undercooling.Furthermore,the curvature su-percooling,constitutional undercooling,thermal undercooling,and kinetic undercooling during sub-rapid solidification were quantitatively determined for given solidification rates.Our results showed that con-stitutional undercooling,rather than thermal undercooling,was primarily responsible for the formation of fine equiaxed grains,with the assistance of Al-5Ti-1B grain refiner.This work provides a new insight into the grain refining mechanism under sub-rapid solidification.展开更多
Transparent electromagnetic(EM)shielding glass with a metal mesh has significant potential for application in different fields of EM radiation and anti-EM interference light-transmitting observation windows.In particu...Transparent electromagnetic(EM)shielding glass with a metal mesh has significant potential for application in different fields of EM radiation and anti-EM interference light-transmitting observation windows.In particular,a transparent EM-shielding glass with a large-aspect-ratio metal mesh can effectively alleviate the contradictory problems of shielding effectiveness and light-transmission performance constraints.However,the fabrication of high-aspect-ratio metal meshes on glass substrates has problems such as high cost,complex processes,low efficiency,small area,and easy damage issues,which limit their application in the field of high-performance,transparent EM-shielding glass.Therefore,this paper proposes a composite additive manufacturing process based on electric-field-driven microjet 3D printing and electroplating.By fabricating metal meshes with an Ag-Cu core-shell structure on a glass substrate,EM-shielding glass with high shielding efficiency and light transmission can be manufactured without increasing the aspect ratio of the metal meshes.The prepared Ag-Cu composite metal mesh has excellent optoelectronic properties(period 250𝜇m,line width 10𝜇m,90.1%transmission at 550 nm visible light,square resistance 0.21Ω/sq),efficient electrothermal effect(3 V DC voltage can reach 189°C steady-state temperature),stable EM-shielding effectiveness(average shielding effectiveness 23 dB at X-band),and acceptable mechanical and environmental stability(less than 3%change in square resistance after 150-times adhesion test and less than 6%and 0.6%change in resistance after 72 h in acid and alkali environments,respectively).This method provides a new solution for the mass production of high-performance large-area transparent electric heating/EM-shielding glass.展开更多
Multilayer frequency selective surfaces(FSSs)have become core components of multi-band communication systems because they possess high selectivity,stability,and out-of-band suppression capabilities.However,interlayer ...Multilayer frequency selective surfaces(FSSs)have become core components of multi-band communication systems because they possess high selectivity,stability,and out-of-band suppression capabilities.However,interlayer reliability problems have negatively affected the manufacture of multilayer FSSs for many years,and these negative impacts are primarily reflected in restrictions in the interlayer bonding strength and the interlayer alignment accuracy.To address these problems,a macroscopic-microscopic cross-scale,multi-material integrated additive manufacturing process was designed during this study.This process,which utilizes electric field-driven(EFD)jet printing and in-situ curing,produced multilayer FSS structures with high-resolution patterning(with a line width of<20μm)and a low alignment error(equal to 0.73%of the periodic dimension).A highly stable micro-interdiffused polyimide(PI)material,which was used for interlayer bonding,was developed by performing trifluoromethyl and fluorenyl side-chain modifications.This material exhibited both extreme environmental adaptability(the PI-based electrodes fabricated using this material exhibited a resistance change rate of less than 5%at 360°C)and a strong interlayer interfacial bonding strength(>3.37 MPa).Using this process and material,a dual-band FSS with passband center frequencies at 14.5 and 60 GHz was designed and fabricated.In addition,the flexibility of the PI material enabled the resultant FSSs to conform to deployable curved surfaces;thus,this material offers a simplified 2D-to-3D fabrication solution for deployable radomes.The proposed binder-free integrated forming process combines environmental sustainability with costeffectiveness;therefore,it serves as a novel strategy for rapid manufacture and performance optimizations of high-frequency communication devices.展开更多
Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy ...Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy from electronics to outside by thermal conductive materials.Compared to the conventional thermal management materials,flexible thermally conductive films with high in-plane thermal conductivity,as emerging candidates,have aroused greater interest in the last decade,which show great potential in thermal management applications of next-generation devices.However,a comprehensive review of flexible thermally conductive films is rarely reported.Thus,we review recent advances of both intrinsic polymer films and polymer-based composite films with ultrahigh in-plane thermal conductivity,with deep understandings of heat transfer mechanism,processing methods to enhance thermal conductivity,optimization strategies to reduce interface thermal resistance and their potential applications.Lastly,challenges and opportunities for the future development of flexible thermally conductive films are also discussed.展开更多
The microstructure and mechanical properties of 304 L stainless steel fabricated by selective laser melting are investigated in this study.With the optimized laser processing parameters,a relative density of 99.9%is a...The microstructure and mechanical properties of 304 L stainless steel fabricated by selective laser melting are investigated in this study.With the optimized laser processing parameters,a relative density of 99.9%is achieved with fine austenite grains and nanoscale cellular subgrains in size of approximately 0.5μm.The presence ofδ-ferrite andσphase precipitates is identified by the x-ray diffraction and transmission electron microscopy.Moreover,the microstructure is identified as an austenite matrix with about 4%δ-ferrite and a trace amount ofσphase by using electron backscattered diffraction analysis.These smallσphase particles are mainly distributed along austenite grain boundaries.Furthermore,the presence of nanoscale cellular subgrains contributes to the good tensile strength and ductility of the selective laser melted 304 L,along with precipitate strengthening and strain hardening.Tensile property anisotropy is also identified in this 304 L,which is attributed to the microstructure difference on vertical and horizontal planes.展开更多
Flexible and stretchable transparent electrodes are widely used in smart display,energy,wearable devices and other fields.Due to the limitations of flexibility and stretchability of indium tin oxide electrodes,alterna...Flexible and stretchable transparent electrodes are widely used in smart display,energy,wearable devices and other fields.Due to the limitations of flexibility and stretchability of indium tin oxide electrodes,alternative electrodes have appeared,such as metal films,metal nanowires,and conductive meshes.However,few of the above electrodes can simultaneously have excellent flexibility,stretchability,and optoelectronic properties.Nanofiber(NF),a continuous ultra-long one-dimensional conductive material,is considered to be one of the ideal materials for high-performance transparent electrodes with excellent properties due to its unique structure.This paper summarizes the important research progress of NF flexible transparent electrodes(FTEs)in recent years from the aspects of NF electrode materials,preparation technology and application.First,the unique advantages and limitations of various NF materials are systematically discussed.Then,we summarize the preparation technology of various advanced NF FTEs,and point out the future development trend.We also discuss the application of NFs in solar cells,supercapacitors,electric heating equipments,sensors,etc,and analyze its development potential in flexible electronic equipment,as well as problems that need to be solved.Finally,the challenges and future development trends are proposed in the wide application of NF FTEs in the field of flexible optoelectronics.展开更多
A transient three-dimensional powder-scale model was established for understanding the flow field and mass transfer within the molten pool during the selective laser melting(SLM)of Inconel 718 alloy by considering som...A transient three-dimensional powder-scale model was established for understanding the flow field and mass transfer within the molten pool during the selective laser melting(SLM)of Inconel 718 alloy by considering some important physical phenomena,such as,a transition from powder to solid,nonlinearities produced by temperature-dependent materials’properties,and fluid flow in the calculation.The influence of laser power or scanning speed on the flow field and cooling rate was discussed in detail.The simulation results reveal that the motion of molten pool and higher cooling rate promote the mass transfer and benefit the solute distribution by increasing laser power.However,with increasing the scanning speed,the melt flow speed and cooling rate are elevated,resulting in an agglomeration of the solute elements,which is ascribed to the shorter dwelling time of liquid.Therefore,the segregation of Nb can be effectively suppressed by increasing laser power or decreasing scanning speed,which can decrease the dwelling time of liquid.展开更多
Continuous fiber reinforced polymer composites(CFRPC)have been widely used in the field of automobile,air-craft,and space due to light weight,high specific strength and modulus in comparison with metal as well as allo...Continuous fiber reinforced polymer composites(CFRPC)have been widely used in the field of automobile,air-craft,and space due to light weight,high specific strength and modulus in comparison with metal as well as alloys.Innovation on 3D printing of CFRPCs opened a new era for the design and fabrication of complicated composite structure with high performance and low cost.3D printing of CFRPCs provided an enabling technol-ogy to bridge the gaps between advanced materials and innovative structures.State-of-art has been reviewed according to the correlations of materials,structure,process,and performance as well as functions in 3D printing of CFRPCs.Typical applications and future perspective for 3D printing of CFRPCs were illustrated in order to grasp the opportunities and face the challenges,which need much more interdisciplinary researches covering the advanced materials,process and equipment,structural design,and final smart performance.展开更多
基金financial support by the open foundation of State Key Laboratory of Chemical Engineering(SKL-Ch E-24B03)the Natural Science Foundation of Shandong Province,China(ZR2021QE098)financial support from the Start-Up Research Fund from the University of Macao(SRG2024-00034-IAPME).
文摘Aqueous zinc(Zn)-ion batteries(ZIBs)have garnered significant attention as promising energy storage devices,primarily due to their low cost,high power density,and excellent safety profile.However,the commercial viability of these batteries is hindered by several issues related to the Zn metal anode,including dendritic growth,hydrogen evolution reaction(HER),surface corrosion,and passivation.This review delves into the root causes and key factors influencing these challenges from both electrochemical thermodynamics and kinetics perspectives.Subsequently,viable strategies to mitigate these issues are systematically summarized,including Zn anode reconstruction,artificial solid-electrolyte interphase(SEI)protection,electrolyte formulation optimization,and separator functionalization.Recent research advancements are examined thoroughly,with a focus on the mechanisms behind these approaches and the resulting battery performance.The review also critically assesses the strengths and limitations of these solutions.Finally,we highlight crucial research directions aimed at advancing the practical application of Zn metal anodes in future aqueous ZIBs.
基金supported by the National Natural Science Foundation of China(Grant Nos.52375348 and 52175331)the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2020ZD04 and ZR2022ME014).
文摘Flexible transparent antennas(FTAs)are widely used in wireless transmission fields,and their technological iterations are accelerating.However,the high losses caused by materials and structures limit the development of FTAs with both high light transmission and high gain,and the rapid iteration rate demands greater process flexibility,which makes it difficult for existing technologies to achieve both demands.Here,we design a novel shell-core structure composite metal mesh(CMM)FTA to achieve extremely low skin depth loss and ohmic loss using skin effect and report a novel hybrid additive manufacturing method based on electric field oriented deposition to achieve efficient and flexible manufacturing of the unique Ag/Cu core-shell structure CMM FTA.The typical sample has a light transmittance of 80%(including substrate)when the sheet resistance is 0.29Ω·sq^(-1),and has excellent bending and torsion resistance.The peak gain in the working band is as high as 5.22 dB,and the efficiency is 80%,which is close to the performance of the opaque Cu patch antenna.It also realizes smooth and stable real-time wireless transmission under bending and long-distance conditions.This method addresses the shortcomings of FTAs,namely their high cost,low manufacturing efficiency,and low performance,especially in the rapid iterative development of antennas.
基金Financial support from the National Natural Science Foundation of China(Nos.52222409,52074132,U19A2084)the National Key Research and Development Program(No.2022YFE0122000)are greatly acknowledged.
文摘It is commonly recognized that the cooling rate has a substantial effect on solute partitioning and its resultant microsegregation during solidification.The classical dendrite tip undercooling theory clarifies the mitigation of microsegregation by increasing the cooling rate.However,most of the studies focused on binary alloys,leaving an open question as to whether the microsegregation of different solutes in a multi-component alloy system exhibits a relieving degree similar to increasing cooling rate.Taking a widely used 6022-type Al alloy(Al-0.76Mg-0.93Si-0.2Fe)as a model alloy,the current study reveals that the microsegregation of Mg gets alleviated to the greatest extent,followed by those of Si and Fe when the cooling rate increases from 5 to 128 K/s.This phenomenon is attributed to the solute-based difference in response to partitioning to cooling rate(denoted as Rk).We propose a theoretical equation to quantify Rk,and the R_(k)values of solute Mg,Si,and Fe successfully explain the rank of solute partitioning in exper-iments.Furthermore,a broad range of R_(k)values of other commonly used alloying elements in Al alloys were calculated and ranked,delivering a handy tool to predict the microsegregation behavior and sol-ubility of different solute elements upon sub-rapid solidification,which is consistent with experimental observation.This framework can also be extended to other multi-component alloy systems.
基金supported by National Natural Science Foundation of China(Grant Nos.52375348,52175331)Guangdong Basic and Applied Basic Research Foundation of China(Grant No.2023A1515110698)Guangzhou Municipal Science and Technology Bureau of China(Grant No.2023A04J1303).
文摘Arbitrary and high-precision thermal patterning has long been desired in the field of thermal functional materials.However,existing thermal patterning strategies have not been widely applied,either hampered by the difficulty in fabricating anisotropic metamaterials or limited by complex thermal manipulation.We propose an on-demand thermal patterning scheme that sandwiches geometrically engineered heating arrays between a substrate and an encapsulation layer to form composite structures and control the omnidirectional transfer of the heat flux gen-erated by the heating arrays.These heating arrays are digitally assembled from multiple heater cells of varying widths and continuously printed using electric-field-driven 3D printing.A design strategy for thermal patterning with good uniformity within individual regions and high contrast between regions is proposed.The performance of the on-demand thermal patterning is verified via high-precision thermal printing.The proposed scheme pro-vides a general and reproducible method for designing thermal functional materials,with potential applications in thermochromics,messaging,thermal camouflage,and illusions.
基金supported by National Natural Science Foundation of China(Grant Nos.52375348,52175331)National Natural Science Foundation of Shandong Province(Grant Nos.ZR2022ME014,ZR2020ZD04).
文摘Specially shaped permanent magnet structures can satisfy the requirements of equipment with limited space or unique shapes.Thereby,these optimize the distribution of magnetic fields.However,traditional manufacturing methods are limited by the mold design and insufficient material utilization.In this study,a polymer-based Nd_(2)Fe_(14)B(NdFeB)magnetic slurry was developed based on direct ink writing(DIW)3D printing technology.A rapidly volatilizable magnetic slurry was used to achieve 3D oriented controllable layering,thus realizing the direct molding fabrication of NdFeB permanent magnets with complex structures.By exploring and optimizing the 3D printing process parameters,specially shaped bonded NdFeB permanent magnet structures with high precision and shape fidelity were prepared.The test results indicated that the remnant magnetization of the printed magnets was proportional to the NdFeB content in the slurry,the coercivity closely matched that of the original powder,and the mechanical properties of the printed magnets were favorable.Building on this,a magnetically driven helical-structure robot was designed and printed to achieve stable motion in low-Reynolds-number fluids.This paper presents a new,low-cost solution for the room-temperature preparation of shape-bonded NdFeB permanent magnets.
基金supported by National Natural Science Foundation of China(Grant Nos.52275345,52175331,51875300)Support Plan for Outstanding Youth Innovation Team in Universities of Shandong Province,China(Grant No.2021KJ044)Natural Science Foundation of Shandong Province,China(Grant No.ZR2020ZD04).
文摘Electrohydrodynamic(EHD)jet printing is a promising method for high-resolution manufacturing;however,it often suffers from jet deflection owing to the accumulation of residual charges within printed structures.These residual charges lead to jet deflection.This study introduces a novel noncontact electric field-driven(NEFD)jet micro 3D printing technique to address these challenges.By decoupling the high-voltage power supply from both the printing material and substrate,NEFD jet micro 3D printing eliminates the pathway for charge injection into the printing material,reducing residual charges by a factor of five or more compared to EHD jet printing.Our research revealed an inherent attractive force between the material jet and previously deposited material,regardless of the material used.Furthermore,we demonstrate that employing a pre-defined allowance printing strategy during fabrication reduces the standard deviation of actual fiber spacing values from 11.4μm to 1.5μm,thereby improving the fiber spacing consistency.This enhanced control enabled the successful fabrication of line patterns with 20±1μm fiber diameters and 61.1±1.9μm fiber spacing,demonstrating the feasibility of NEFD jet micro 3D printing.This technique offers a novel solution for mitigating the challenges associated with electric fields and charge accumulation in EHD jet printing,paving the way for enhanced resolution and material compatibility in micro-/nanoscale additive manufacturing.
基金National Natural Science Foundation of China(Grant Nos.52275345,52175331)the Support plan for Outstanding Youth Innovation Team in Universities of Shandong Province,China(2021KJ044)Natural Science Foundation of Shandong Province,China(Granted No.ZR2020ZD04)。
文摘Electrohydrodynamic(EHD)jet printing represents a novel micro/nano-scale additive manufacturing process that utilises a high-voltage induced electric field between the nozzle and the substrate to print micro/nanoscale structures.EHD printing is particularly advantageous for the fabrication on flexible or non-flat substrates and of large aspect ratio micro/nanostructures and composite multi-material structures.Despite this,EHD printing has yet to be fully industrialised due to its low throughput,which is primarily caused by the limitations of serial additive printing technology.The parallel multi-nozzle array-based process has become the most promising option for EHD printing to achieve large-scale printing by increasing the number of nozzles to realise multichannel parallel printing.This paper reviews the recent development of multi-nozzle EHD printing technology,analyses jet motion with multi-nozzle,explains the origins of the electric field crosstalk effect under multi-nozzle and discusses several widely used methods for overcoming it.This work also summarises the impact of different process parameters on multi-nozzle EHD printing and describes the current manufacturing process using multi-nozzle as well as the method by which they can be realised independently.In addition,it presents an additional significant utilisation of multi-nozzle printing aside from enhancing single-nozzle production efficiency,which is the production of composite phase change materials through multi-nozzle.Finally,the future direction of multi-nozzle EHD printing development is discussed and envisioned.
基金supported by the National Natural Science Foundation of China (NSFC) (Nos.51871168,52271012)the Natural Sciences and Engineering Research Council of Canada (NSERC)in the form of international research collaboration.Q.C.,A.H.F.,and S.J.Q.are grateful to the Southwest Institute of Technology and Engineering Cooperation Fund (No.HDHDW5902020102)H.W.acknowledges the financial support of the National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact (No.6142902220301).
文摘Increasingly harsh service conditions place higher requirements for the high strain-rate performance of titanium alloys.Adiabatic shear band(ASB),a phenomenon prone to dynamic loading,is often accom-panied by catastrophic damage.Yet,it is unclear how the internal nanostructures are related to shear instability.Here we report detailed microstructural evolution in the ASB of a titanium alloy via in-depth focused ion beam(FIB),transmission Kikuchi diffraction(TKD),and high-resolution transmission electron microscope(HRTEM)analyses,with the deformation instability phenomenon discussed from the energy perspective.The ASB interior undergoes multifaceted changes,namely deformation-induced beta-to-alpha transformation and deformation-induced martensitic transformation to form substantially refined and heterogeneous structures.Meanwhile,two types of extremely fine twins are identified to occur within both nano-sized martensite and alpha phase.The critical plastic work representing the onset of adiabatic shear instability and dynamic equilibrium is observed to be constant for a specific structure in the same deformation mode.The energy analysis could be extended to other materials subjected to high strain-rate dynamic deformation.
基金the financial support received from the National Science Foundation (NSF-CMMI 2131441) under the direction of Dr.Alexis Lewis。
文摘Nitrogen processed, cold sprayed commercially pure(CP)-Al coatings on Mg-based alloys mostly lack acceptable hardness, wear resistance and most importantly are highly susceptible to localized corrosion in chloride containing solutions. In this research, commercially pure α-Ti top coating having good pitting potential(~1293 mV_(SCE)), high microhardness(HV_(0.025): 263.03) and low wear rate was applied on a CP-Al coated Mg-based alloy using high pressure cold spray technology. Potentiodynamic polarization(PDP) curves indicated that the probability of transition from metastable pits to the stable pits for cold spayed(CS) Al coating is considerably higher compared to that with the CS Ti top coating(for Ti/Al/Mg system). In addition, CS Ti top coating was in the passivation region in most pH ranges even after 48 h immersion in 3.5 wt% NaCl solution. The stored energy in the CS Ti top coating(as a passive metal) was presumed to be responsible for the easy passivation. Immersion tests indicated no obvious pits formation on the intact CS Ti top coating surface and revealed effective corrosion protection performance of the CS double layered noble barrier coatings on Mg alloys in 3.5 wt% NaCl solution even after 264 h.
基金Financial supports from the National Natural Science Foun-dation of China(Nos.52222409,52074132,U19A2084,and U22A20109)are greatly acknowledgedPartial financial support came from the National Key Research and Development Program(No.2022YFE0122000)+1 种基金the Interdisciplinary Integration and Inno-vation Project of JLU(No.JLUXKJC2021ZZ08)the Fundamental Research Funds for the Central Universities,JLU.
文摘The mechanical properties of as-cast metallic materials depend strongly on the size and shape of grains,which are critical microstructural parameters dictated by the interplay of nucleation and growth of crys-talline solids during solidification.In our experiments,the microstructure transition from coarse colum-nar crystals into fine equiaxed crystals for dilute Al-Mn-Si alloys was achieved by using sub-rapid so-lidification with the addition of Al-5Ti-1B grain refiner.The average grain size of Al alloy was reduced from a millimeter size to 73μm.Through temperature gradient calculation,we found that the acqui-sition of fine equiaxed crystals could be attributed to the existence of a high number density of TiB2,acting as effective nucleation sites with an increase in total undercooling.Furthermore,the curvature su-percooling,constitutional undercooling,thermal undercooling,and kinetic undercooling during sub-rapid solidification were quantitatively determined for given solidification rates.Our results showed that con-stitutional undercooling,rather than thermal undercooling,was primarily responsible for the formation of fine equiaxed grains,with the assistance of Al-5Ti-1B grain refiner.This work provides a new insight into the grain refining mechanism under sub-rapid solidification.
基金supported by National Natural Science Foundation of China(Grant No.52175331)Shandong Provincial National Natural Science Foundation of China(Grant Nos.ZR2020ZD04,ZR2022ME014,ZR2022QE077)Support Plan for Outstanding Youth Innovation Team in Universities of Shandong Province of China(Grant No.2020KJB003).
文摘Transparent electromagnetic(EM)shielding glass with a metal mesh has significant potential for application in different fields of EM radiation and anti-EM interference light-transmitting observation windows.In particular,a transparent EM-shielding glass with a large-aspect-ratio metal mesh can effectively alleviate the contradictory problems of shielding effectiveness and light-transmission performance constraints.However,the fabrication of high-aspect-ratio metal meshes on glass substrates has problems such as high cost,complex processes,low efficiency,small area,and easy damage issues,which limit their application in the field of high-performance,transparent EM-shielding glass.Therefore,this paper proposes a composite additive manufacturing process based on electric-field-driven microjet 3D printing and electroplating.By fabricating metal meshes with an Ag-Cu core-shell structure on a glass substrate,EM-shielding glass with high shielding efficiency and light transmission can be manufactured without increasing the aspect ratio of the metal meshes.The prepared Ag-Cu composite metal mesh has excellent optoelectronic properties(period 250𝜇m,line width 10𝜇m,90.1%transmission at 550 nm visible light,square resistance 0.21Ω/sq),efficient electrothermal effect(3 V DC voltage can reach 189°C steady-state temperature),stable EM-shielding effectiveness(average shielding effectiveness 23 dB at X-band),and acceptable mechanical and environmental stability(less than 3%change in square resistance after 150-times adhesion test and less than 6%and 0.6%change in resistance after 72 h in acid and alkali environments,respectively).This method provides a new solution for the mass production of high-performance large-area transparent electric heating/EM-shielding glass.
基金supported by the National Natural Science Foundation of China(Grant Nos.52375348,52175331)the National Natural Science Foundation of Shandong Province(Grant No.ZR2022ME014)the Taishan Scholars Program of Shandong Province(Grant No.tsqn202408219)。
文摘Multilayer frequency selective surfaces(FSSs)have become core components of multi-band communication systems because they possess high selectivity,stability,and out-of-band suppression capabilities.However,interlayer reliability problems have negatively affected the manufacture of multilayer FSSs for many years,and these negative impacts are primarily reflected in restrictions in the interlayer bonding strength and the interlayer alignment accuracy.To address these problems,a macroscopic-microscopic cross-scale,multi-material integrated additive manufacturing process was designed during this study.This process,which utilizes electric field-driven(EFD)jet printing and in-situ curing,produced multilayer FSS structures with high-resolution patterning(with a line width of<20μm)and a low alignment error(equal to 0.73%of the periodic dimension).A highly stable micro-interdiffused polyimide(PI)material,which was used for interlayer bonding,was developed by performing trifluoromethyl and fluorenyl side-chain modifications.This material exhibited both extreme environmental adaptability(the PI-based electrodes fabricated using this material exhibited a resistance change rate of less than 5%at 360°C)and a strong interlayer interfacial bonding strength(>3.37 MPa).Using this process and material,a dual-band FSS with passband center frequencies at 14.5 and 60 GHz was designed and fabricated.In addition,the flexibility of the PI material enabled the resultant FSSs to conform to deployable curved surfaces;thus,this material offers a simplified 2D-to-3D fabrication solution for deployable radomes.The proposed binder-free integrated forming process combines environmental sustainability with costeffectiveness;therefore,it serves as a novel strategy for rapid manufacture and performance optimizations of high-frequency communication devices.
基金funded by the National Natural Science Foundation of China (NNSFC grant nos. 52103034, 51873126, 52175331 and 52003170)Shandong Provincial Natural Science Foundation (ZR2021QE014, ZR2020ZD04)
文摘Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy from electronics to outside by thermal conductive materials.Compared to the conventional thermal management materials,flexible thermally conductive films with high in-plane thermal conductivity,as emerging candidates,have aroused greater interest in the last decade,which show great potential in thermal management applications of next-generation devices.However,a comprehensive review of flexible thermally conductive films is rarely reported.Thus,we review recent advances of both intrinsic polymer films and polymer-based composite films with ultrahigh in-plane thermal conductivity,with deep understandings of heat transfer mechanism,processing methods to enhance thermal conductivity,optimization strategies to reduce interface thermal resistance and their potential applications.Lastly,challenges and opportunities for the future development of flexible thermally conductive films are also discussed.
基金supported financially by the National Key R&D Program of China(Nos.2018 YFB1106100)the Special funds for Future Industries of Shenzhen(Project No.JSGG20170824104916638)。
文摘The microstructure and mechanical properties of 304 L stainless steel fabricated by selective laser melting are investigated in this study.With the optimized laser processing parameters,a relative density of 99.9%is achieved with fine austenite grains and nanoscale cellular subgrains in size of approximately 0.5μm.The presence ofδ-ferrite andσphase precipitates is identified by the x-ray diffraction and transmission electron microscopy.Moreover,the microstructure is identified as an austenite matrix with about 4%δ-ferrite and a trace amount ofσphase by using electron backscattered diffraction analysis.These smallσphase particles are mainly distributed along austenite grain boundaries.Furthermore,the presence of nanoscale cellular subgrains contributes to the good tensile strength and ductility of the selective laser melted 304 L,along with precipitate strengthening and strain hardening.Tensile property anisotropy is also identified in this 304 L,which is attributed to the microstructure difference on vertical and horizontal planes.
基金supported by the National Natural Science Foundation of China(Grant No.52175331)the Support plan for Outstanding Youth Innovation Team in Universities of Shandong Province,China(Grand No.2020KJB003)Natural Science Foundation of Shandong Province,China(Granted Nos.ZR2022ME014,ZR2021ME139 and ZR2020ZD04)。
文摘Flexible and stretchable transparent electrodes are widely used in smart display,energy,wearable devices and other fields.Due to the limitations of flexibility and stretchability of indium tin oxide electrodes,alternative electrodes have appeared,such as metal films,metal nanowires,and conductive meshes.However,few of the above electrodes can simultaneously have excellent flexibility,stretchability,and optoelectronic properties.Nanofiber(NF),a continuous ultra-long one-dimensional conductive material,is considered to be one of the ideal materials for high-performance transparent electrodes with excellent properties due to its unique structure.This paper summarizes the important research progress of NF flexible transparent electrodes(FTEs)in recent years from the aspects of NF electrode materials,preparation technology and application.First,the unique advantages and limitations of various NF materials are systematically discussed.Then,we summarize the preparation technology of various advanced NF FTEs,and point out the future development trend.We also discuss the application of NFs in solar cells,supercapacitors,electric heating equipments,sensors,etc,and analyze its development potential in flexible electronic equipment,as well as problems that need to be solved.Finally,the challenges and future development trends are proposed in the wide application of NF FTEs in the field of flexible optoelectronics.
基金the financial support from the National Natural Science Foundation of China(Nos.51425402 and 51501048)。
文摘A transient three-dimensional powder-scale model was established for understanding the flow field and mass transfer within the molten pool during the selective laser melting(SLM)of Inconel 718 alloy by considering some important physical phenomena,such as,a transition from powder to solid,nonlinearities produced by temperature-dependent materials’properties,and fluid flow in the calculation.The influence of laser power or scanning speed on the flow field and cooling rate was discussed in detail.The simulation results reveal that the motion of molten pool and higher cooling rate promote the mass transfer and benefit the solute distribution by increasing laser power.However,with increasing the scanning speed,the melt flow speed and cooling rate are elevated,resulting in an agglomeration of the solute elements,which is ascribed to the shorter dwelling time of liquid.Therefore,the segregation of Nb can be effectively suppressed by increasing laser power or decreasing scanning speed,which can decrease the dwelling time of liquid.
基金supported by National Key R&D Program of China(Grant No.2018YFE0207900)National Natural Science Foundation of China(Grant No.52075422)+1 种基金K C Wong Education FoundationThe Youth Innovation Team of Shaanxi Universities.
文摘Continuous fiber reinforced polymer composites(CFRPC)have been widely used in the field of automobile,air-craft,and space due to light weight,high specific strength and modulus in comparison with metal as well as alloys.Innovation on 3D printing of CFRPCs opened a new era for the design and fabrication of complicated composite structure with high performance and low cost.3D printing of CFRPCs provided an enabling technol-ogy to bridge the gaps between advanced materials and innovative structures.State-of-art has been reviewed according to the correlations of materials,structure,process,and performance as well as functions in 3D printing of CFRPCs.Typical applications and future perspective for 3D printing of CFRPCs were illustrated in order to grasp the opportunities and face the challenges,which need much more interdisciplinary researches covering the advanced materials,process and equipment,structural design,and final smart performance.
