High-pressure electrides,characterized by the presence of interstitial quasi-atoms(ISQs),possess unique electronic structures and physical properties,such as diverse dimensions of electride states exhibiting different...High-pressure electrides,characterized by the presence of interstitial quasi-atoms(ISQs),possess unique electronic structures and physical properties,such as diverse dimensions of electride states exhibiting different superconductivity,which has attracted significant attention.Here,we report a new electron-deficient type of electride Li_(4)Al and identify its phase transition progress with pressurization,where the internal driving force behind phase transitions,bonding characteristics,and superconducting behaviors have been revealed based on first-principles density functional theory.Through analysis of the bonding properties of electride Li_(4)Al,we demonstrate that the ISQs exhibiting increasingly covalent characteristics between Al ions play a critical role in driving the phase transition.Our electron–phonon coupling calculations indicate that all phases exhibit superconducting behaviors.Importantly,we prove that the ISQs behave as free electrons and demonstrate that the factor governing T_(c) is primarily derived from Li-p-hybridized electronic states with ISQ compositions.These electronic states are scattered by low-frequency phonons arising from mixed vibrations of Li and Al affected by ISQs to enhance electron–phonon coupling.Our study largely expands the research scope of electrides,provides new insight for understanding phase transitions,and elucidates the effects of ISQs on superconducting behavior.展开更多
Prussian blue analogs(PBAs)have emerged as environmentally friendly and structurally tunable cathode materials for aqueous ammonium-ion batteries(AIBs).However,the fundamental role of crystalline H_(2)O in regulating ...Prussian blue analogs(PBAs)have emerged as environmentally friendly and structurally tunable cathode materials for aqueous ammonium-ion batteries(AIBs).However,the fundamental role of crystalline H_(2)O in regulating ammonium-ion storage and transport remains poorly understood.In this study,we present a comprehensive comparison between hydrated NH_(4)NiHCF-H_(2)O and its anhydrous counterpart NH_(4)NiHCF,revealing the critical contribution of interstitial water to electrochemical performance.Structural and spectroscopic analyses confirm that interstitial water forms robust hydrogen bonds with NH_(4)+ions,stabilizing the PBA framework and mitigating structural degradation during cycling.Electrochemical measurements show that NH_(4)NiHCF-H_(2)O delivers a significantly higher specific capacity of 61 mA h g^(−1)at 0.2 C and markedly improved rate performance compared to NH_(4)NiHCF(48 mA h g^(−1)at 0.2 C).Kinetic analysis reveals that interstitial water enhances NH_(4)+diffusion,as evidenced by higher diffusion coefficients.Furthermore,density functional theory(DFT)calculations demonstrate that crystal water acts as a hydrogen bond acceptor,preferentially interacting with NH_(4)+and reducing the migration energy barrier,thereby facilitating fast ion transport.This work provides fundamental insights into the role of crystal water in PBAs and offers a rational design strategy for improving the kinetics,structural stability of PBAs cathodes for AIBs.展开更多
This study investigates the fabrication and characterization of Al alloy matrix composites reinforced with graphene oxide(GO) using accumulative roll bonding(ARB).The annealed Al 6061 sheets were processed through 5-p...This study investigates the fabrication and characterization of Al alloy matrix composites reinforced with graphene oxide(GO) using accumulative roll bonding(ARB).The annealed Al 6061 sheets were processed through 5-pass ARB with GO reinforcement applied during the initial passes.Scanning electron microscopy revealed effective mitigation of GO agglomeration and improved interface bonding due to microscale material mixing.Raman spectroscopy confirmed the strong interaction between GO and the Al alloy matrix,as evidenced by the increased D band intensities and enhanced 2D band symmetry.Mechanical testing indicated an approximately 338.37% increase in yield strength(YS)and 86.42%improvement in hardness for the ARB-processed(ARBed)Al 6061/GO composite(0.2wt%)compared with annealed Al 6061 and an approximately 14.15%increase in YS and 17.23%improvement in hardness for the ARBedAl/GO composite(0.2wt%)compared with unreinforced ARBed Al 6061 specimens after five passes.X-ray diffraction analysis indicated an increased dislocation density,corroborating the observed enhancements in mechanical properties.Fracture surface analysis revealed reduced elongation with deep dimples,highlighting the tradeoff between strength and ductility.These results demonstrate the effectiveness of ARB for integrating GO into the Al 6061 matrix to improve the mechanical performance and interfacial bonding and underscore its potential for advanced composite materials.展开更多
IC10 alloy is a promising material for the applications of engine turbine blades.Fabricating and repairing of the turbine blades urgently need a sound joining technique for the IC10 alloy.The traditional transient liq...IC10 alloy is a promising material for the applications of engine turbine blades.Fabricating and repairing of the turbine blades urgently need a sound joining technique for the IC10 alloy.The traditional transient liquid phase(TLP)bonding method is difficult to achieve isothermal solidification,which tends to form brittle eutectic phases.In this study,a novel Al/BNi2 composite filler was designed.This new type of composite filler facilitates the diffusion of elements to completely dissolve or disperse the brittle eutectic structure of continuous large blocks in the TLP joint,thereby improving the room-temperature mechanical properties of the joint and increasing its average shear strength by 20%to 550 MPa.Effect of Al content and bonding temperature on microstructure and mechanical strength of the IC10/Al/BNi2/IC10 joint was investigated.Microstructure evolution mechanisms of the traditional TLP bonding method(with a pure BNi2 filler)and the novel TLP bonding method(with the Al/BNi2 composite filler)were put into comparison.The TLP joint of the new filler achieved a maximum room temperature shear strength of 570 MPa(3 wt.%Al,1100℃,2 h).展开更多
Recurrence of solid tumors after surgical resection is a major barrier to tissue regeneration.As an emerging treatment strategy,photo-thermo-electric therapy ablates tumor cells via photothermal effects and generates ...Recurrence of solid tumors after surgical resection is a major barrier to tissue regeneration.As an emerging treatment strategy,photo-thermo-electric therapy ablates tumor cells via photothermal effects and generates reactive oxygen species(ROS)via thermoelectric effects to disrupt heat shock proteins,thereby suppressing their protective function in tumor cells.However,conventional materials suffer from low thermoelectric efficiency and weak tissue penetration ability.In this study,we fabricated iodine-doped bismuth sulfide(I-Bi_(2)S_(3))nanorods with bonding heterostructures to improve thermoelectric performance.The approach employed iodine doping to introduce additional electrons,thereby regulating the band structure of Bi_(2)S_(3)and exploiting the dual low-energy vibration effect of the heterostructures to reduce thermal conductivity.More importantly,controlling the type of heterostructure modulated the bandgap width,thereby expanding the light absorption range to the higher-penetration near-infrared(NIR)-Ⅱregion for deep tissue treatment.The I-Bi_(2)S_(3)nanorods were incorporated into poly-L-lactic acid(PLLA)scaffolds to confer antitumor functionality.According to the results,the bonding heterostructures enhanced the conductivity of Bi_(2)S_(3)and reduced its thermal conductivity,significantly enhancing thermoelectric efficacy.The heterostructures reduced the bandgap of Bi_(2)S_(3)from 1.23 to 0.88 eV,enabling optical absorption in the NIR-Ⅱregion.The ROS tests showed that the PLLA/I-Bi_(2)S_(3)scaffold exhibited good photothermal effects and ROS generation under 1064-nm laser irradiation.The antitumor efficacy of the PLLA/I-Bi_(2)S_(3)scaffold reached 84.6%against MG-63 cells,demonstrating its exceptional potential in cancer treatment.展开更多
The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab b...The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab ballastless track structure.This study sought to enhance technical standards for evaluating interfacial bonding properties by suggesting the use of the splitting tensile strength to evaluate the impact of bubble defects.Specimens were fabricated through on-site experiment.The percent of each area of 6 cm^(2)or more bubble defect was 0 in most of specimens.When the cumulative area of all bub-ble defects reached 12%,the splitting tensile strength value was 0.67 MPa,which exceeded the minimum required value of 0.5 MPa for ensuring bonding interface adhesion.Furthermore,when the cumulative area of all bubble defects reached 8%,the splitting tensile strength value was 0.85 MPa,which exceeded the minimum required value of 0.8 MPa,thereby over-coming the negative impact of each area of 10 cm^(2) or more bubble defect.Additionally,keeping the cumulative area of each area of 6 cm^(2) or more bubble defect below 6%ensured adequate bonding strength and reduced the occurrence of specimens with lower splitting tensile strength values.展开更多
When stacking two-dimensional(2D)materials with a lattice mismatch and/or a small twist,moirésuperlattice emerges with fascinating electronic and optical properties.The fabrication of such stacked 2D materials us...When stacking two-dimensional(2D)materials with a lattice mismatch and/or a small twist,moirésuperlattice emerges with fascinating electronic and optical properties.The fabrication of such stacked 2D materials usually requires multiple transfer and stack processes,assisted by a certain transfer medium which needs to be removed afterwards,and it is very challenging to maintain pristine and clean surfaces/interfaces for these stacked structures.In this work,we report a facile direct bonding method for fabrication of twisted MoS_(2) bilayers with ultra-clean surfaces/interfaces.Novel interlayer interactions are revealed in the as-fabricated high-quality samples,leading to twist-angle related dispersion behavior of various Raman modes,such as layer breathing modes,shear modes and E_(2g)modes,as well as indirect bandgap excitons.Field-effect transistors(FETs)of twisted MoS_(2) bilayers also exhibit angle-dependent performance,which could be attributed to the band structure evolution.This facile method holds significance for the future integration of pre-designed multilayer 2D materials and paves a way to explore underlying physical mechanisms and potential applications.展开更多
Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding str...Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.展开更多
A multi-stimuli-responsive hydrogel,P(VI-co-MAAC-NE),was successfully constructed by covalently integrating the aggregation-induced emission(AIE)moiety(Z)-N-(4-(1-cyano-2-(4-(diethylamino)phenyl)vinyl)-phenyl)methacry...A multi-stimuli-responsive hydrogel,P(VI-co-MAAC-NE),was successfully constructed by covalently integrating the aggregation-induced emission(AIE)moiety(Z)-N-(4-(1-cyano-2-(4-(diethylamino)phenyl)vinyl)-phenyl)methacrylamide(NE)into a dynamic hydrogen-bonding network composed of 1-vinylimidazole(VI)and methacrylic acid(MAAC)groups.The dense hydrogen-bonding network not only provides enhanced mechanical robustness,but also significantly enhances the AIE effect of NE by restricting its molecular motion.Under various external stimuli,the hydrogen bonds within the hydrogel network undergo reversible dissociation and reformation,thus enabling synergistic modulation of the hydrogel’s mechanical properties and luminescence behavior.Specifically,organic solvents disrupt the hydrogen-bonding network and the aggregation of the AIE moiety NE,resulting in macroscopic swelling and fluorescence quenching of the hydrogel.In strongly acidic conditions,protonation of NE molecules suppresses the intramolecular charge transfer(ICT)process,yielding a blue-shifted emission band accompanied by intense blue fluorescence;in highly alkaline environments,deprotonation of carboxyl groups induces hydrogel swelling and disperses NE aggregates,leading to pronounced fluorescence quenching.Moreover,the system exhibits thermally activated shape-memory behavior:heating above the glass transition temperature(T_(g):ca.62℃)softens the hydrogel to allow programmable reshaping,and subsequent hydrogen bond reformation at ambient conditions locks in the resultant geometries without sacrificing the hydrogel’s fluorescence performance.By capitalizing on these multi-stimuli-responsive characteristics and shape-memory behavior,the potential of hydrogel P(VI-co-MAAC-NE)for advanced information encryption and anti-counterfeiting applications is demonstrated.This work not only provides a versatile material platform for sensing and information storage,but also offers new insights into the design of intelligent soft materials integrating AIE features with dynamically regulated supramolecular network structures.展开更多
Azobenzene-based polymer actuators show great promise for photoactuation owing to their unique photoisomerization behavior and tailorable molecular programmability.However,conventional systems are limited by inadequat...Azobenzene-based polymer actuators show great promise for photoactuation owing to their unique photoisomerization behavior and tailorable molecular programmability.However,conventional systems are limited by inadequate mechanical robustness,self-healing,and recyclability,hindering their practical implementation.Herein,we present a high-performance azobenzene-functionalized polyurethane(AzoPU)elastomer actuator designed via molecular engineering of photoactive azobenzene moieties and dynamic disulfide bonds.AzoPU exhibits exceptional mechanical properties with retained performance after multiple reshaping cycles,enabled by well-engineered hard-soft segments and synergistic stress dissipation from weak covalent bonds/hierarchical hydrogen bonds.It achieves over 93%self-healing efficiency at room temperature owing to the synergistic interplay of disulfide bonds in the polymer backbone and intermolecular hydrogen bonds.Furthermore,it demonstrates remarkable light-triggered actuation behavior,achieving a phototropic bending angle exceeding 180°toward the light source within 45 s.To showcase its practical potential,proof-of-concept photoactuated devices with flower-,hook-,and gripper-like and local-orientation processed strip-shaped structures were fabricated,which exhibited rapid and reversible light-triggered deformation.This study proposes a novel strategy for the development of intelligent polymeric materials that integrate light responsiveness,self-healing,and recyclability,thus holding great promise for applications in flexible electronics,smart actuators,and sustainable functional materials.展开更多
The carbonylation of amines offers a promising route for synthesizing N-substituted carbamates with high atom economy.However,conventional catalysts exhibit limited catalytic efficiency,and the underlying proton trans...The carbonylation of amines offers a promising route for synthesizing N-substituted carbamates with high atom economy.However,conventional catalysts exhibit limited catalytic efficiency,and the underlying proton transfer mechanism remains elusive.Herein,we reported a metal-free,room-temperature strategy utilizing 1,5,7-triazabicyclo[4.4.0]dec-5-ene(TBD)as a dual hydrogen bond catalyst to synergistically activate propylamine(PA)and dimethyl carbonate(DMC).This green catalytic system achieves a 10-fold acceleration in reaction rate compared to other hydrogen bonding catalysts under mild conditions.This is enabled by dual hydrogen bonding of TBD with PA and DMC,which facilitates rapid proton transfer and stabilizes tetrahedral intermediates.Theoretical calculations confirm that the dual hydrogen bond system significantly lowers activation energy compared to single hydrogen bond analogs.Furthermore,it was revealed that the hydrogen bonding network within the product is the primary factor responsible for the sluggish reaction rate.This study demonstrates the effectiveness of a dual hydrogen bond system in accelerating the carbonylation of amines and provides a green route to access carbamates.展开更多
To combine the high elasticity and good mechanical performance of isoprene rubber(IR)with excellent fatigue resistance and low heat build-up of Eucommia ulmoides gum(EUG),the present study employed a chemical method t...To combine the high elasticity and good mechanical performance of isoprene rubber(IR)with excellent fatigue resistance and low heat build-up of Eucommia ulmoides gum(EUG),the present study employed a chemical method to graft 4-amino pyridine(AP)onto epoxidized IR and EUG,thereby creating a chemical assembly rubber of amino-pyridine-grafted epoxidized IR(AP-EIR)and amino pyridine-grafted epoxidized EUG(AP-EEUG)via a dynamic hydrogen bonding network.The presence of hydrogen bonds between AP-EIR and AP-EEUG was confirmed by variable temperature infrared spectroscopy,whereas scanning electron microscopy-energy dispersive spectroscopy revealed a uniform dispersion of zinc oxide and nano-fillers.Hydrogen bonds significantly facilitate strain-induced crystallization between the AP-EIR and AP-EEUG molecules,thereby strengthening their intermolecular interactions.During mechanical deformation,the material primarily dissipates energy through the breaking of hydrogen bonds,which effectively improves the mechanical strength of the material,and the introduction of amino groups in this chemical assembly rubber improves the uniform dispersion of nano-fillers,as well as the interface interaction between rubber and nano-fillers.Consequently,the chemically assembled rubber exhibited superior modulus,tensile strength,and tear strength compared to IR and its physical blend,while also demonstrating reduced heat build-up during dynamic loading.展开更多
The excellent irradiation resistance,high strength and plasticity exhibited by high-entropy alloys(HEAs)make it candidate for engin-eering applications.Diffusion bonding of Al_(0.3)CoCrFeNi single-phase HEAs was carri...The excellent irradiation resistance,high strength and plasticity exhibited by high-entropy alloys(HEAs)make it candidate for engin-eering applications.Diffusion bonding of Al_(0.3)CoCrFeNi single-phase HEAs was carried out using electric-assisted diffusion bonding(EADB),and the effect of bonding temperature on the evolution of the interfacial microstructure and the mechanical properties was investigated.The results indicate that as the bonding temperature increases,the pores at the interface gradually decrease in size and undergo closure.The electric current significantly promotes the pore closure mechanism dominated by plastic deformation at the diffusion interface and promotes the recrystallisation behavior at the interface,and the fracture mode changes from intergranular fracture at the interface to jagged fracture along the grains spanning the weld parent material.Due to the activation effect of EADB,higher-strength diffusion bonding of high-entropy alloys can be achieved at the same temperature compared with the conventional hot-pressure diffusion bonding(HPDB)process.展开更多
Surface chemistry plays a critical role in the fields of electrochemistry,heterogeneous catalysis,adsorption,etc.[1–4].The representative D-band center theory reported through Hammer and Nørskov in surface chemi...Surface chemistry plays a critical role in the fields of electrochemistry,heterogeneous catalysis,adsorption,etc.[1–4].The representative D-band center theory reported through Hammer and Nørskov in surface chemistry has been widely used in early studies to predict adsorption strength[5,6].Generally,the adsorption strength of active sites correlates inversely with the downward shift of the D-band center(εd)relative to the Fermi level,as lower-energy positioning increases anti-bonding orbital occupancy,weakening surface interactions(Fig.1(a)).展开更多
Surface tension-induced shrinkage of heterogeneously bonded interfaces is a key factor in limiting the performance of nanostructures.Herein,we demonstrate a laser-induced thermo-compression bonding technology to suppr...Surface tension-induced shrinkage of heterogeneously bonded interfaces is a key factor in limiting the performance of nanostructures.Herein,we demonstrate a laser-induced thermo-compression bonding technology to suppress surface tension-induced shrinkage of Cu-Au bonded interface.A focused laser beam is used to apply localized heating and scattering force to the exposed Cu nanowire.The laser-induced scattering force and the heating can be adjusted by regulating the exposure intensity.When the ratio of scattering forces to the gravity of the exposed nanowire reaches 3.6×10^(3),the molten Cu nanowire is compressed into flattened shape rather than shrinking into nanosphere by the surface tension.As a result,the Cu-Au bonding interface is broadened fourfold by the scattering force,leading to a reduction in contact resistance of approximately 56%.This noncontact thermo-compression bonding technology provides significant possibilities for the interconnect packaging and integration of nanodevices.展开更多
Due to its superior nanoscale properties,cobalt(Co)is highly desirable for ultrahigh-density 3D integration into materials through metal/dielectric hybrid bonding.However,this process is very challenging through Co/Si...Due to its superior nanoscale properties,cobalt(Co)is highly desirable for ultrahigh-density 3D integration into materials through metal/dielectric hybrid bonding.However,this process is very challenging through Co/SiO_(2)hybrid bonding,as very hydrophilic SiO_(2)surfaces are needed for bonding during dehydration reactions and oxidation of the Co surfaces must be avoided.Additionally,the substantial coefficient of thermal expansion mismatch between the robust capping layers(Co and SiO_(2)layers)necessitates hybrid bonding with minimal thermal input and compression.In this study,we introduce a ternary plasma activation strategy employing an Ar/NH_(3)/H_(2)O gas mixture to facilitate Co/SiO_(2)hybrid bonding at temperatures as low as~200℃,which is markedly lower than the melting point of Co(~1500℃).Intriguingly,non-oxide metallization at the Co-Co interface can be realized without the hindrance of a bonding barrier,thereby reducing the electrical resistance by over 40%and compression force requirements.Moreover,the enhancement in the SiO_(2)surface energy through active group terminations fosters extensive interfacial hydration and strengthens the mechanical properties.This research paves the way for fine-tuning bonding surfaces using a material-selective strategy which should advance metal/dielectric hybrid bonding for future integration applications.展开更多
Interfacial evolution and bonding mechanism of reduced activation ferritic/martensitic(RAFM)steel were systematically investigated through a series of hot compression tests conducted at various strains(0.15-0.8),strai...Interfacial evolution and bonding mechanism of reduced activation ferritic/martensitic(RAFM)steel were systematically investigated through a series of hot compression tests conducted at various strains(0.15-0.8),strain rates(0.001-1 s^(-1)),and temperatures(950-1050℃).Interfacial microstructural analysis revealed that plastic deformation of surface asperities effectively removes interfacial voids,and the evolution of dynamic recrystallization(DRX)aids in achieving a joint characterized by homogeneously refined microstructure and adequate interfacial grain boundary(IGB)migration.Electron backscattered diffraction analysis demonstrated that the continuous dynamic recrystallization,characterized by progressive subgrain rotation,is the prevailing DRX nucleation mechanism in RAFM steel during hot compression bonding.During DRX evolution,emerging DRX grains in the interfacial region expand into adjacent areas,transforming T-type triple junction grain boundaries into equal form,and resulting in a serrated and intricate interface.Elevated temperatures and strains,coupled with reduced strain rates,augment DRX grain nucleation and IGB migration,thus enhancing RAFM joint quality with regard to the interface bonding ratio and the interface migration ratio.展开更多
Flexible strain sensors have received tremendous attention because of their potential applications as wearable sensing devices.However, the integration of key functions into a single sensor, such as high stretchabilit...Flexible strain sensors have received tremendous attention because of their potential applications as wearable sensing devices.However, the integration of key functions into a single sensor, such as high stretchability, low hysteresis, self-adhesion, andexcellent antifreezing performance, remains an unmet challenge. In this respect, zwitterionic hydrogels have emerged asideal material candidates for breaking through the above dilemma. The mechanical properties of most reported zwitterionichydrogels, however, are relatively poor, significantly restricting their use under load-bearing conditions. Traditional improve-ment approaches often involve complex preparation processes, making large-scale production challenging. Additionally,zwitterionic hydrogels prepared with chemical crosslinkers are typically fragile and prone to irreversible deformation underlarge strains, resulting in the slow recovery of structure and function. To fundamentally enhance the mechanical properties ofpure zwitterionic hydrogels, the most effective approach is the regulation of the chemical structure of zwitterionic monomersthrough a targeted design strategy. This study employed a novel zwitterionic monomer carboxybetaine urethane acrylate(CBUTA), which contained one urethane group and one carboxybetaine group on its side chain. Through the direct polym-erization of ultrahigh concentration monomer solutions without adding any chemical crosslinker, we successfully developedpure zwitterionic supramolecular hydrogels with significantly enhanced mechanical properties, self-adhesive behavior, andantifreezing performance. Most importantly, the resultant zwitterionic hydrogels exhibited high tensile strength and tough-ness and displayed ultralow hysteresis under strain conditions up to 1100%. This outstanding performance was attributedto the unique liquid–liquid phase separation phenomenon induced by the ultrahigh concentration of CBUTA monomers inan aqueous solution, as well as the enhanced polymer chain entanglement and the strong hydrogen bonds between urethanegroups on the side chains. The potential application of hydrogels in strain sensors and high-performance triboelectric nano-generators was further explored. Overall, this work provides a promising strategy for developing pure zwitterionic hydrogelsfor flexible strain sensors and self-powered electronic devices.展开更多
High Nbβ/γ-TiAl(HNBG)intermetallics and Ni-based superalloy(IN718)were diffusion-bonded using pure Ti foil interlayer under pulse current.The microstructure,element segregation,and mechanical properties of HNBG/Ti/I...High Nbβ/γ-TiAl(HNBG)intermetallics and Ni-based superalloy(IN718)were diffusion-bonded using pure Ti foil interlayer under pulse current.The microstructure,element segregation,and mechanical properties of HNBG/Ti/IN718 joint were investigated.The effect of Ti interlayer on microstructure and mechanical properties of the joint was discussed.The typical microstructure of HNBG/Ti/IN718 joint was HNBG//β/B2,τ_(3)-NiAl_(3)Ti_(2)//α_(2)-Ti_(3)Al//α-Ti+δ-NiTi_(2),β-Ti//δ-NiTi_(2)//β2-(Ni,Fe)Ti//Cr/Fe-richη-Ni_(3)Ti,η-Ni_(3)Ti,α-Cr,δ-Ni_(3)Nb//η-Ni_(3)Ti,γ-Ni,δ-Ni_(3)Nb//IN718.The gaps and Kirkendall voids exhibited a gradual disappearance with increasing bonding temperature.The mechanism of Cr,Fe and Nb elements segregation was that NiTi phase hindered the diffusion of them.The nano-indentation results demonstrated that diffusion zones on IN718 alloy side had higher hardness.The maximum shear strength of the joint(326 MPa)was achieved at bonding parameters of 850℃,20 min and 10 MPa.The fracture occurred in Zones IV and V,and the fracture modes were brittle fracture and cleavage fracture.The introduction of Ti interlayer resulted in improved microstructure and enhanced bonding strength of the joint.展开更多
基金supported by the National Key Research and Development Program of China (Grant Nos.2023YFA1406200 and 2022YFA-1405500)the National Natural Science Foundation of China (Grant Nos.12304021 and 52072188)+3 种基金Zhejiang Provincial Natural Science Foundation of China (Grant Nos.LQ23A040004 and MS26A040028)Natural Science Foundation of Ningbo (Grant Nos.2022J091 and ZX2025001430)the Program for Science and Technology Innovation Team in Zhejiang (Grant No.2021R01004)the Program for Changjiang Scholars and Innovative Research Team in University (Grant No.IRT_15R23)。
文摘High-pressure electrides,characterized by the presence of interstitial quasi-atoms(ISQs),possess unique electronic structures and physical properties,such as diverse dimensions of electride states exhibiting different superconductivity,which has attracted significant attention.Here,we report a new electron-deficient type of electride Li_(4)Al and identify its phase transition progress with pressurization,where the internal driving force behind phase transitions,bonding characteristics,and superconducting behaviors have been revealed based on first-principles density functional theory.Through analysis of the bonding properties of electride Li_(4)Al,we demonstrate that the ISQs exhibiting increasingly covalent characteristics between Al ions play a critical role in driving the phase transition.Our electron–phonon coupling calculations indicate that all phases exhibit superconducting behaviors.Importantly,we prove that the ISQs behave as free electrons and demonstrate that the factor governing T_(c) is primarily derived from Li-p-hybridized electronic states with ISQ compositions.These electronic states are scattered by low-frequency phonons arising from mixed vibrations of Li and Al affected by ISQs to enhance electron–phonon coupling.Our study largely expands the research scope of electrides,provides new insight for understanding phase transitions,and elucidates the effects of ISQs on superconducting behavior.
基金supported by the National Natural Science Foundation of China (52172227)the Natural Science Foundation of Hubei Province (2023AFA114)+2 种基金the Guizhou Provincial Key Technology R&D Program (ZD[2025]019)provided by the Startup Fund (20QD80 and 22QD28)support from the Science&Technology Top Talents Program of Guizhou Province ([2024]349)
文摘Prussian blue analogs(PBAs)have emerged as environmentally friendly and structurally tunable cathode materials for aqueous ammonium-ion batteries(AIBs).However,the fundamental role of crystalline H_(2)O in regulating ammonium-ion storage and transport remains poorly understood.In this study,we present a comprehensive comparison between hydrated NH_(4)NiHCF-H_(2)O and its anhydrous counterpart NH_(4)NiHCF,revealing the critical contribution of interstitial water to electrochemical performance.Structural and spectroscopic analyses confirm that interstitial water forms robust hydrogen bonds with NH_(4)+ions,stabilizing the PBA framework and mitigating structural degradation during cycling.Electrochemical measurements show that NH_(4)NiHCF-H_(2)O delivers a significantly higher specific capacity of 61 mA h g^(−1)at 0.2 C and markedly improved rate performance compared to NH_(4)NiHCF(48 mA h g^(−1)at 0.2 C).Kinetic analysis reveals that interstitial water enhances NH_(4)+diffusion,as evidenced by higher diffusion coefficients.Furthermore,density functional theory(DFT)calculations demonstrate that crystal water acts as a hydrogen bond acceptor,preferentially interacting with NH_(4)+and reducing the migration energy barrier,thereby facilitating fast ion transport.This work provides fundamental insights into the role of crystal water in PBAs and offers a rational design strategy for improving the kinetics,structural stability of PBAs cathodes for AIBs.
文摘This study investigates the fabrication and characterization of Al alloy matrix composites reinforced with graphene oxide(GO) using accumulative roll bonding(ARB).The annealed Al 6061 sheets were processed through 5-pass ARB with GO reinforcement applied during the initial passes.Scanning electron microscopy revealed effective mitigation of GO agglomeration and improved interface bonding due to microscale material mixing.Raman spectroscopy confirmed the strong interaction between GO and the Al alloy matrix,as evidenced by the increased D band intensities and enhanced 2D band symmetry.Mechanical testing indicated an approximately 338.37% increase in yield strength(YS)and 86.42%improvement in hardness for the ARB-processed(ARBed)Al 6061/GO composite(0.2wt%)compared with annealed Al 6061 and an approximately 14.15%increase in YS and 17.23%improvement in hardness for the ARBedAl/GO composite(0.2wt%)compared with unreinforced ARBed Al 6061 specimens after five passes.X-ray diffraction analysis indicated an increased dislocation density,corroborating the observed enhancements in mechanical properties.Fracture surface analysis revealed reduced elongation with deep dimples,highlighting the tradeoff between strength and ductility.These results demonstrate the effectiveness of ARB for integrating GO into the Al 6061 matrix to improve the mechanical performance and interfacial bonding and underscore its potential for advanced composite materials.
基金funded by the National Natural Science Foundation of China(Grant No.U2167216,52504408,52475335)China Postdoctoral Science Foundation Funded Project(Grant No.2024M754181).
文摘IC10 alloy is a promising material for the applications of engine turbine blades.Fabricating and repairing of the turbine blades urgently need a sound joining technique for the IC10 alloy.The traditional transient liquid phase(TLP)bonding method is difficult to achieve isothermal solidification,which tends to form brittle eutectic phases.In this study,a novel Al/BNi2 composite filler was designed.This new type of composite filler facilitates the diffusion of elements to completely dissolve or disperse the brittle eutectic structure of continuous large blocks in the TLP joint,thereby improving the room-temperature mechanical properties of the joint and increasing its average shear strength by 20%to 550 MPa.Effect of Al content and bonding temperature on microstructure and mechanical strength of the IC10/Al/BNi2/IC10 joint was investigated.Microstructure evolution mechanisms of the traditional TLP bonding method(with a pure BNi2 filler)and the novel TLP bonding method(with the Al/BNi2 composite filler)were put into comparison.The TLP joint of the new filler achieved a maximum room temperature shear strength of 570 MPa(3 wt.%Al,1100℃,2 h).
基金National Key Research and Development Program of China(No.2023YFB4605800)The National Natural Science Foundation of China(Nos.52475362,52365046,and 52465041)+3 种基金Jiangxi Provincial Natural Science Foundation of China(No.20224ACB204013)Jiangxi Provincial Key Laboratory of Additive Manufacturing of Implantable Medical Device(No.2024SSY11161)Jiangxi Provincial Department of Education Science and Technology Project(No.GJJ2400708)Jiangxi Province Science and Technology Program(Nos.20252BAC200317 and 20252BEJ730195)。
文摘Recurrence of solid tumors after surgical resection is a major barrier to tissue regeneration.As an emerging treatment strategy,photo-thermo-electric therapy ablates tumor cells via photothermal effects and generates reactive oxygen species(ROS)via thermoelectric effects to disrupt heat shock proteins,thereby suppressing their protective function in tumor cells.However,conventional materials suffer from low thermoelectric efficiency and weak tissue penetration ability.In this study,we fabricated iodine-doped bismuth sulfide(I-Bi_(2)S_(3))nanorods with bonding heterostructures to improve thermoelectric performance.The approach employed iodine doping to introduce additional electrons,thereby regulating the band structure of Bi_(2)S_(3)and exploiting the dual low-energy vibration effect of the heterostructures to reduce thermal conductivity.More importantly,controlling the type of heterostructure modulated the bandgap width,thereby expanding the light absorption range to the higher-penetration near-infrared(NIR)-Ⅱregion for deep tissue treatment.The I-Bi_(2)S_(3)nanorods were incorporated into poly-L-lactic acid(PLLA)scaffolds to confer antitumor functionality.According to the results,the bonding heterostructures enhanced the conductivity of Bi_(2)S_(3)and reduced its thermal conductivity,significantly enhancing thermoelectric efficacy.The heterostructures reduced the bandgap of Bi_(2)S_(3)from 1.23 to 0.88 eV,enabling optical absorption in the NIR-Ⅱregion.The ROS tests showed that the PLLA/I-Bi_(2)S_(3)scaffold exhibited good photothermal effects and ROS generation under 1064-nm laser irradiation.The antitumor efficacy of the PLLA/I-Bi_(2)S_(3)scaffold reached 84.6%against MG-63 cells,demonstrating its exceptional potential in cancer treatment.
基金supported by a grant from China railway corporation science and technology research and development plan project(Grant No.2017G005-B)funding support by Wuyi University’s Hong Kong and Macao Joint Research and Development Fund(Grants No.2021WGALH15)funding support by the Innovation and Technology Commission of Hong Kong SAR Government to the Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center(Grant No.K-BBY1).
文摘The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab ballastless track structure.This study sought to enhance technical standards for evaluating interfacial bonding properties by suggesting the use of the splitting tensile strength to evaluate the impact of bubble defects.Specimens were fabricated through on-site experiment.The percent of each area of 6 cm^(2)or more bubble defect was 0 in most of specimens.When the cumulative area of all bub-ble defects reached 12%,the splitting tensile strength value was 0.67 MPa,which exceeded the minimum required value of 0.5 MPa for ensuring bonding interface adhesion.Furthermore,when the cumulative area of all bubble defects reached 8%,the splitting tensile strength value was 0.85 MPa,which exceeded the minimum required value of 0.8 MPa,thereby over-coming the negative impact of each area of 10 cm^(2) or more bubble defect.Additionally,keeping the cumulative area of each area of 6 cm^(2) or more bubble defect below 6%ensured adequate bonding strength and reduced the occurrence of specimens with lower splitting tensile strength values.
基金supported by Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030002)the National Key Research and Development Program(Grant No.2021YFA1202900)the National Natural Science Foundation of China(Grant Nos.62204166 and 62404145)。
文摘When stacking two-dimensional(2D)materials with a lattice mismatch and/or a small twist,moirésuperlattice emerges with fascinating electronic and optical properties.The fabrication of such stacked 2D materials usually requires multiple transfer and stack processes,assisted by a certain transfer medium which needs to be removed afterwards,and it is very challenging to maintain pristine and clean surfaces/interfaces for these stacked structures.In this work,we report a facile direct bonding method for fabrication of twisted MoS_(2) bilayers with ultra-clean surfaces/interfaces.Novel interlayer interactions are revealed in the as-fabricated high-quality samples,leading to twist-angle related dispersion behavior of various Raman modes,such as layer breathing modes,shear modes and E_(2g)modes,as well as indirect bandgap excitons.Field-effect transistors(FETs)of twisted MoS_(2) bilayers also exhibit angle-dependent performance,which could be attributed to the band structure evolution.This facile method holds significance for the future integration of pre-designed multilayer 2D materials and paves a way to explore underlying physical mechanisms and potential applications.
基金supported by the National Key R&D Program of China (No. 2018YFA0707300)the National Natural Science Foundation of China (No. 52374376)the Introduction Plan for High end Foreign Experts, China (No. G2023105001L)。
文摘Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.
文摘A multi-stimuli-responsive hydrogel,P(VI-co-MAAC-NE),was successfully constructed by covalently integrating the aggregation-induced emission(AIE)moiety(Z)-N-(4-(1-cyano-2-(4-(diethylamino)phenyl)vinyl)-phenyl)methacrylamide(NE)into a dynamic hydrogen-bonding network composed of 1-vinylimidazole(VI)and methacrylic acid(MAAC)groups.The dense hydrogen-bonding network not only provides enhanced mechanical robustness,but also significantly enhances the AIE effect of NE by restricting its molecular motion.Under various external stimuli,the hydrogen bonds within the hydrogel network undergo reversible dissociation and reformation,thus enabling synergistic modulation of the hydrogel’s mechanical properties and luminescence behavior.Specifically,organic solvents disrupt the hydrogen-bonding network and the aggregation of the AIE moiety NE,resulting in macroscopic swelling and fluorescence quenching of the hydrogel.In strongly acidic conditions,protonation of NE molecules suppresses the intramolecular charge transfer(ICT)process,yielding a blue-shifted emission band accompanied by intense blue fluorescence;in highly alkaline environments,deprotonation of carboxyl groups induces hydrogel swelling and disperses NE aggregates,leading to pronounced fluorescence quenching.Moreover,the system exhibits thermally activated shape-memory behavior:heating above the glass transition temperature(T_(g):ca.62℃)softens the hydrogel to allow programmable reshaping,and subsequent hydrogen bond reformation at ambient conditions locks in the resultant geometries without sacrificing the hydrogel’s fluorescence performance.By capitalizing on these multi-stimuli-responsive characteristics and shape-memory behavior,the potential of hydrogel P(VI-co-MAAC-NE)for advanced information encryption and anti-counterfeiting applications is demonstrated.This work not only provides a versatile material platform for sensing and information storage,but also offers new insights into the design of intelligent soft materials integrating AIE features with dynamically regulated supramolecular network structures.
基金financially supported by the National Natural Science Foundation of China(No.52503154)Shandong Provincial Natural Science Foundation(Nos.ZR2022MB034 and ZR2025QC512)。
文摘Azobenzene-based polymer actuators show great promise for photoactuation owing to their unique photoisomerization behavior and tailorable molecular programmability.However,conventional systems are limited by inadequate mechanical robustness,self-healing,and recyclability,hindering their practical implementation.Herein,we present a high-performance azobenzene-functionalized polyurethane(AzoPU)elastomer actuator designed via molecular engineering of photoactive azobenzene moieties and dynamic disulfide bonds.AzoPU exhibits exceptional mechanical properties with retained performance after multiple reshaping cycles,enabled by well-engineered hard-soft segments and synergistic stress dissipation from weak covalent bonds/hierarchical hydrogen bonds.It achieves over 93%self-healing efficiency at room temperature owing to the synergistic interplay of disulfide bonds in the polymer backbone and intermolecular hydrogen bonds.Furthermore,it demonstrates remarkable light-triggered actuation behavior,achieving a phototropic bending angle exceeding 180°toward the light source within 45 s.To showcase its practical potential,proof-of-concept photoactuated devices with flower-,hook-,and gripper-like and local-orientation processed strip-shaped structures were fabricated,which exhibited rapid and reversible light-triggered deformation.This study proposes a novel strategy for the development of intelligent polymeric materials that integrate light responsiveness,self-healing,and recyclability,thus holding great promise for applications in flexible electronics,smart actuators,and sustainable functional materials.
基金financially supported by the National Key R&D Program of China(2023YFC3905400)the Clean Combustion and Low-carbon Utilization of Coal,Strategic Priority Research Program of the Chinese Academy of Sciences,Grant No.XDA 29000000.
文摘The carbonylation of amines offers a promising route for synthesizing N-substituted carbamates with high atom economy.However,conventional catalysts exhibit limited catalytic efficiency,and the underlying proton transfer mechanism remains elusive.Herein,we reported a metal-free,room-temperature strategy utilizing 1,5,7-triazabicyclo[4.4.0]dec-5-ene(TBD)as a dual hydrogen bond catalyst to synergistically activate propylamine(PA)and dimethyl carbonate(DMC).This green catalytic system achieves a 10-fold acceleration in reaction rate compared to other hydrogen bonding catalysts under mild conditions.This is enabled by dual hydrogen bonding of TBD with PA and DMC,which facilitates rapid proton transfer and stabilizes tetrahedral intermediates.Theoretical calculations confirm that the dual hydrogen bond system significantly lowers activation energy compared to single hydrogen bond analogs.Furthermore,it was revealed that the hydrogen bonding network within the product is the primary factor responsible for the sluggish reaction rate.This study demonstrates the effectiveness of a dual hydrogen bond system in accelerating the carbonylation of amines and provides a green route to access carbamates.
基金financially supported by the National Natural Science Foundation of China(No.52341301)Liaoning Provincial Department of Education Basic Research Project,China(Nos.LJKZZ20220055 and JYTMS20231498)Shenyang Natural Science Foundation Special,China(No.23-503-6-06).
文摘To combine the high elasticity and good mechanical performance of isoprene rubber(IR)with excellent fatigue resistance and low heat build-up of Eucommia ulmoides gum(EUG),the present study employed a chemical method to graft 4-amino pyridine(AP)onto epoxidized IR and EUG,thereby creating a chemical assembly rubber of amino-pyridine-grafted epoxidized IR(AP-EIR)and amino pyridine-grafted epoxidized EUG(AP-EEUG)via a dynamic hydrogen bonding network.The presence of hydrogen bonds between AP-EIR and AP-EEUG was confirmed by variable temperature infrared spectroscopy,whereas scanning electron microscopy-energy dispersive spectroscopy revealed a uniform dispersion of zinc oxide and nano-fillers.Hydrogen bonds significantly facilitate strain-induced crystallization between the AP-EIR and AP-EEUG molecules,thereby strengthening their intermolecular interactions.During mechanical deformation,the material primarily dissipates energy through the breaking of hydrogen bonds,which effectively improves the mechanical strength of the material,and the introduction of amino groups in this chemical assembly rubber improves the uniform dispersion of nano-fillers,as well as the interface interaction between rubber and nano-fillers.Consequently,the chemically assembled rubber exhibited superior modulus,tensile strength,and tear strength compared to IR and its physical blend,while also demonstrating reduced heat build-up during dynamic loading.
基金support from National Natural Science Foundation of China(NSFC,Grant numbers U22A20185,U21A20128,52175302 and 52305353)Aeronautical Science Foundation(ASFC-20230036077001)Fundamental Research Funds for the Central Universities(2022FRFK060009,HIT.DZI1.2023012).
文摘The excellent irradiation resistance,high strength and plasticity exhibited by high-entropy alloys(HEAs)make it candidate for engin-eering applications.Diffusion bonding of Al_(0.3)CoCrFeNi single-phase HEAs was carried out using electric-assisted diffusion bonding(EADB),and the effect of bonding temperature on the evolution of the interfacial microstructure and the mechanical properties was investigated.The results indicate that as the bonding temperature increases,the pores at the interface gradually decrease in size and undergo closure.The electric current significantly promotes the pore closure mechanism dominated by plastic deformation at the diffusion interface and promotes the recrystallisation behavior at the interface,and the fracture mode changes from intergranular fracture at the interface to jagged fracture along the grains spanning the weld parent material.Due to the activation effect of EADB,higher-strength diffusion bonding of high-entropy alloys can be achieved at the same temperature compared with the conventional hot-pressure diffusion bonding(HPDB)process.
文摘Surface chemistry plays a critical role in the fields of electrochemistry,heterogeneous catalysis,adsorption,etc.[1–4].The representative D-band center theory reported through Hammer and Nørskov in surface chemistry has been widely used in early studies to predict adsorption strength[5,6].Generally,the adsorption strength of active sites correlates inversely with the downward shift of the D-band center(εd)relative to the Fermi level,as lower-energy positioning increases anti-bonding orbital occupancy,weakening surface interactions(Fig.1(a)).
基金supported by the National Natural Science Foundation of China(Nos.52305612 and U20A6004)Open Fund of Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration(Wuhan University)(NO.EMPI2023015).
文摘Surface tension-induced shrinkage of heterogeneously bonded interfaces is a key factor in limiting the performance of nanostructures.Herein,we demonstrate a laser-induced thermo-compression bonding technology to suppress surface tension-induced shrinkage of Cu-Au bonded interface.A focused laser beam is used to apply localized heating and scattering force to the exposed Cu nanowire.The laser-induced scattering force and the heating can be adjusted by regulating the exposure intensity.When the ratio of scattering forces to the gravity of the exposed nanowire reaches 3.6×10^(3),the molten Cu nanowire is compressed into flattened shape rather than shrinking into nanosphere by the surface tension.As a result,the Cu-Au bonding interface is broadened fourfold by the scattering force,leading to a reduction in contact resistance of approximately 56%.This noncontact thermo-compression bonding technology provides significant possibilities for the interconnect packaging and integration of nanodevices.
基金supported by the National Natural Science Foundation of China(Grant Nos.92164105 and 51975151)the Heilongjiang Provincial Natural Science Foundation of China under grant LH2019E041+1 种基金the Heilongjiang Touyan Innovation Team Program(HITTY-20190013)State Key Laboratory of Precision Welding&Joining of Materials and Structures(No.24-T-04)。
文摘Due to its superior nanoscale properties,cobalt(Co)is highly desirable for ultrahigh-density 3D integration into materials through metal/dielectric hybrid bonding.However,this process is very challenging through Co/SiO_(2)hybrid bonding,as very hydrophilic SiO_(2)surfaces are needed for bonding during dehydration reactions and oxidation of the Co surfaces must be avoided.Additionally,the substantial coefficient of thermal expansion mismatch between the robust capping layers(Co and SiO_(2)layers)necessitates hybrid bonding with minimal thermal input and compression.In this study,we introduce a ternary plasma activation strategy employing an Ar/NH_(3)/H_(2)O gas mixture to facilitate Co/SiO_(2)hybrid bonding at temperatures as low as~200℃,which is markedly lower than the melting point of Co(~1500℃).Intriguingly,non-oxide metallization at the Co-Co interface can be realized without the hindrance of a bonding barrier,thereby reducing the electrical resistance by over 40%and compression force requirements.Moreover,the enhancement in the SiO_(2)surface energy through active group terminations fosters extensive interfacial hydration and strengthens the mechanical properties.This research paves the way for fine-tuning bonding surfaces using a material-selective strategy which should advance metal/dielectric hybrid bonding for future integration applications.
基金The authors are grateful to the National Natural Science Foundation of China(Grant Nos.52034004 and 52271111)the National Key R&D Program of China(2022YFB3705300)for grant and financial support.
文摘Interfacial evolution and bonding mechanism of reduced activation ferritic/martensitic(RAFM)steel were systematically investigated through a series of hot compression tests conducted at various strains(0.15-0.8),strain rates(0.001-1 s^(-1)),and temperatures(950-1050℃).Interfacial microstructural analysis revealed that plastic deformation of surface asperities effectively removes interfacial voids,and the evolution of dynamic recrystallization(DRX)aids in achieving a joint characterized by homogeneously refined microstructure and adequate interfacial grain boundary(IGB)migration.Electron backscattered diffraction analysis demonstrated that the continuous dynamic recrystallization,characterized by progressive subgrain rotation,is the prevailing DRX nucleation mechanism in RAFM steel during hot compression bonding.During DRX evolution,emerging DRX grains in the interfacial region expand into adjacent areas,transforming T-type triple junction grain boundaries into equal form,and resulting in a serrated and intricate interface.Elevated temperatures and strains,coupled with reduced strain rates,augment DRX grain nucleation and IGB migration,thus enhancing RAFM joint quality with regard to the interface bonding ratio and the interface migration ratio.
基金supported by the National Natural Science Foundation of China(Nos.T2222013 and 52073203)Tianjin Natural Science Foundation(No.22JCQNJC01040)the State Key Laboratory of Molecular Engineering of Polymers(Fudan University)(No.K2024-19).
文摘Flexible strain sensors have received tremendous attention because of their potential applications as wearable sensing devices.However, the integration of key functions into a single sensor, such as high stretchability, low hysteresis, self-adhesion, andexcellent antifreezing performance, remains an unmet challenge. In this respect, zwitterionic hydrogels have emerged asideal material candidates for breaking through the above dilemma. The mechanical properties of most reported zwitterionichydrogels, however, are relatively poor, significantly restricting their use under load-bearing conditions. Traditional improve-ment approaches often involve complex preparation processes, making large-scale production challenging. Additionally,zwitterionic hydrogels prepared with chemical crosslinkers are typically fragile and prone to irreversible deformation underlarge strains, resulting in the slow recovery of structure and function. To fundamentally enhance the mechanical properties ofpure zwitterionic hydrogels, the most effective approach is the regulation of the chemical structure of zwitterionic monomersthrough a targeted design strategy. This study employed a novel zwitterionic monomer carboxybetaine urethane acrylate(CBUTA), which contained one urethane group and one carboxybetaine group on its side chain. Through the direct polym-erization of ultrahigh concentration monomer solutions without adding any chemical crosslinker, we successfully developedpure zwitterionic supramolecular hydrogels with significantly enhanced mechanical properties, self-adhesive behavior, andantifreezing performance. Most importantly, the resultant zwitterionic hydrogels exhibited high tensile strength and tough-ness and displayed ultralow hysteresis under strain conditions up to 1100%. This outstanding performance was attributedto the unique liquid–liquid phase separation phenomenon induced by the ultrahigh concentration of CBUTA monomers inan aqueous solution, as well as the enhanced polymer chain entanglement and the strong hydrogen bonds between urethanegroups on the side chains. The potential application of hydrogels in strain sensors and high-performance triboelectric nano-generators was further explored. Overall, this work provides a promising strategy for developing pure zwitterionic hydrogelsfor flexible strain sensors and self-powered electronic devices.
基金supported by the National Natural Science Foundation of China(Nos.52071021,51871012)Beijing Natural Science Foundation,China(No.2162024)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.FRF-GF-20-20B)the National Program on Key Basic Research Project of China(No.2011CB605502).
文摘High Nbβ/γ-TiAl(HNBG)intermetallics and Ni-based superalloy(IN718)were diffusion-bonded using pure Ti foil interlayer under pulse current.The microstructure,element segregation,and mechanical properties of HNBG/Ti/IN718 joint were investigated.The effect of Ti interlayer on microstructure and mechanical properties of the joint was discussed.The typical microstructure of HNBG/Ti/IN718 joint was HNBG//β/B2,τ_(3)-NiAl_(3)Ti_(2)//α_(2)-Ti_(3)Al//α-Ti+δ-NiTi_(2),β-Ti//δ-NiTi_(2)//β2-(Ni,Fe)Ti//Cr/Fe-richη-Ni_(3)Ti,η-Ni_(3)Ti,α-Cr,δ-Ni_(3)Nb//η-Ni_(3)Ti,γ-Ni,δ-Ni_(3)Nb//IN718.The gaps and Kirkendall voids exhibited a gradual disappearance with increasing bonding temperature.The mechanism of Cr,Fe and Nb elements segregation was that NiTi phase hindered the diffusion of them.The nano-indentation results demonstrated that diffusion zones on IN718 alloy side had higher hardness.The maximum shear strength of the joint(326 MPa)was achieved at bonding parameters of 850℃,20 min and 10 MPa.The fracture occurred in Zones IV and V,and the fracture modes were brittle fracture and cleavage fracture.The introduction of Ti interlayer resulted in improved microstructure and enhanced bonding strength of the joint.
