The migration and transformation of hexavalent chromium(Cr(VI))in the environment are regulated by pyrite(FeS2).However,variations in pyrite crystal facets influence the adsorption behavior and electron transfer betwe...The migration and transformation of hexavalent chromium(Cr(VI))in the environment are regulated by pyrite(FeS2).However,variations in pyrite crystal facets influence the adsorption behavior and electron transfer between pyrite and Cr(VI),thereby impacting the Cr(VI)reduction performance.Herein,two naturally common facets of pyritewere synthesized hydrothermally to investigate the facet-dependent mechanisms of Cr(VI)reduction.The experimental results revealed that the{111}facet exhibited approximately 1.30–1.50 times higher efficiency in Cr(VI)reduction compared to the{100}facet.Surface analyses and electrochemical results indicated that{111}facet displayed a higher iron-sulfur oxidation level,which was affected by its superior electrochemical properties during the reaction with Cr(VI).Density functional theory(DFT)calculations demonstrated that the narrower band gap and lower work function on{111}facet were more favorable for the electron transfer between Fe(II)and Cr(VI).Furthermore,different adsorption configurations were observed on{100}and{111}surfaces due to the unique arrangements of Fe and S atoms.Specifically,O atoms in Cr_(2)O_(7)^(2−)directly bound with the S sites on{100}but the Fe sites on{111}.According to the density of states(DOS),the Fe site had better reactivity than the S site in the reaction,which appeared to be related to the fracture of S-S bonds.Additionally,the adsorption configuration of Cr_(2)O_(7)^(2−)on{111}surface showed a stronger adsorption energy and a more stable coordination mode,favoring subsequent Cr(VI)reduction process.These findings provide an in-depth analysis of facet-dependent mechanisms underlying Cr(VI)reduction behavior,offering new insights into studying environmental interactions between heavy metals and natural minerals.展开更多
Multifunctional compatible stealth materials have emerged as the focal point of contemporary protection technology research and vanadium-based nanomaterials play a pivotal role in the development of advanced stealth m...Multifunctional compatible stealth materials have emerged as the focal point of contemporary protection technology research and vanadium-based nanomaterials play a pivotal role in the development of advanced stealth materials.Here,a compatible stealth aerogel is successfully synthesized by employing mixed-valence decavanadate as the vanadium oxide(VO_(x))molecular model.Ultralight{VⅣVV_(9)}/MXene aerogel(0.0429 g cm^(-3))exhibits exceptional radar stealth performance with a minimal reflection loss(RL_(min))of−57.74 dB(99.9998%EMW absorption)and a significantly superior radar cross section reduction value of 26.77 dB m2.The aerogel’s exceptional properties,including a low infrared(IR)emissivity(0.479)and a low thermal conductivity of(32.30 mW m^(-1)K^(-1)),are crucial for enabling compatibility with IR and thermal stealth technologies.The presence of a mixed-valence polyoxovanadate cluster leads to an increase in the Schottky barrier and enhances magnetic properties,consequently boosting interfacial polarization and contributing to magnetic losses during electromagnetic wave(EMW)absorption.Consequently,altering the number of valence electrons significantly enhances the compatible stealth capabilities.These findings contribute significantly to our comprehension of how microstructure impacts EMW absorption processes and provide a basis for further research into the development of VO_(x)-based compatible stealth materials.展开更多
Proton exchange membrane fuel cell(PEMFC)is a promising clean energy source,but its performance and stability are vulnerable to the negative effects of humidity conditions.The gas diffusion substrate(GDS)plays a pivot...Proton exchange membrane fuel cell(PEMFC)is a promising clean energy source,but its performance and stability are vulnerable to the negative effects of humidity conditions.The gas diffusion substrate(GDS)plays a pivotal role in regulating the moisture and gas transport.The single pore structure of traditionally designed GDS often leads to the pathway competition between moisture and gas,which effects the efficiency of fuel cells.In this study,we report on a hierarchical fibrous paper with tunable hierarchical pores for a sustainable GDS.This design offers gas permeability under wet conditions,by separating the gas pathway from the moisture pathway,thus mitigating their pathway competition.In addition,this paper forms a multi-scale scaffold that absorbs moisture under high humidity conditions and releases it under dry conditions.It is allowed to maintain an optimal internal humidity and further enhances the humidity adaptability.Furthermore,the carbon footprint is only 15.97%,significantly lower than commercial alternatives.This feature makes it a sustainable solution to stabilize PEMFCs under diverse humidity conditions.展开更多
The conversion process of chitin,one of the abundant biomass resources on the earth,not only follows the principles of green chemistry,but also has significant value in industrial applications.However,it is a great ch...The conversion process of chitin,one of the abundant biomass resources on the earth,not only follows the principles of green chemistry,but also has significant value in industrial applications.However,it is a great challenge to directly convert insoluble and rigid structured chitin to 5-hydroxymethylfurfural(HMF).To address this issue,we developed a green conversion process combining pretreatment and catalytic system.Chitin was first pretreated by hexafluoro isopropanol(HFIP),which somewhat disrupted the hydrogen bonding network within the chitin structure.Subsequently,formic acid(FA)and silicotungstic acid(STA)synergistically catalyzed the conversion to HMF in a biphasic system of 2-methyltetrahydrofuran(2-Me-THF)/H2O,and high yields(40.2%)HMF was obtained under the optimism conditions.The product distribution was analyzed by HPLC-MS and the co-catalysis of FA with STA was evidenced.A dual-function catalytic system with both Lewis and Br?nsted acids was created,the catalytic system that significantly improved the efficiency of complex tandem catalytic reactions with chitin.Based on the experimental results,a possible pathway for chitin conversion was deduced,providing a new catalytic idea for the efficient conversion of chitin to HMF.展开更多
Eutectic high-entropy alloys(EHEAs),combining the advantages of both eutectic alloys and high-entropy alloys(HEAs),possess good castability and superior comprehensive mechanical properties which are regarded as a revo...Eutectic high-entropy alloys(EHEAs),combining the advantages of both eutectic alloys and high-entropy alloys(HEAs),possess good castability and superior comprehensive mechanical properties which are regarded as a revolutionary material system.In this paper,a current study of EHEAs is captured comprehensively for the first time,including basic theory,microstructure and deformation behavior,and alloy design.An in-depth analysis of the formation of different microstructures of EHEAs and their mechanical properties is presented,and four methods of designing EHEAs are summarized.Due to their unique characteristics,EHEAs show great potential in materials processing engineering.Here we give a comprehensive summary of their applications in welding,surface engineering,and additive manufacturing for the first time.Among them,EHEAs in welding are divided into three sections based on different welding techniques:fusion-based welding,solid-state welding,and diffusion reaction-based welding;EHEAs in surface engineering are separated into two parts:surface modification of bulk EHEAs and EHEA coatings;EHEAs in additive manufacturing are elaborated in two parts:laser powder bed fusion(LPBF)and laser direct energy deposition(LDED).Finally,a summary is given and a future outlook is prospected.展开更多
Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is ...Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is critical for a microelectronic interconnection,will go through a phase transition at temperatures between 186 and 189℃.This research conducted an in-situ TEM study of a micro Cu/ENIG/Sn solder joint under isothermal aging test and proposed a model to illustrate the mechanism of the microstructural evolution.The results showed that part of the Sn solder reacted with Cu diffused from the electrode to formη´-Cu_(6)Sn_(5)during the ultrasonic bonding process,while the rest of Sn was left and enriched in a region in the solder joint.But the enriched Sn quickly diffused to both sides when the temperature reached 100℃,reacting with the ENIG coating and Cu to form(Ni_(x)Cu_(1-x))_(3)Sn_(4),AuSn_(4),and Cu_(6)Sn_(5)IMCs.After entering the heat preservation process,the diffusion of Cu from the electrode to the joint became more intense,resulting in the formation of Cu_(3)Sn.The scallop-type Cu_(6)Sn_(5)and the seahorse-type Cu_(3)Sn constituted a typical two-layered structure in the solder joint.Most importantly,the transition betweenηandη’was captured near the phase transition temperature for Cu_(6)Sn_(5)during both the heating and cooling process,which was accompanied by a volume shifting,and the transition process was further studied.This research is expected to serve as a reference for the service of micro Cu/ENIG/Sn solder joints in the electronic industry.展开更多
Rapid acquisition of rock structure information during tunnel construction is crucial for optimizing subsequent construction strategies and avoiding engineering rock disasters.In this regard,this study proposes the be...Rapid acquisition of rock structure information during tunnel construction is crucial for optimizing subsequent construction strategies and avoiding engineering rock disasters.In this regard,this study proposes the best time to obtain rock structure information on the tunnel face during the construction period.By summarizing relevant studies on rock information acquisition locally and abroad and combining them with the actual situation during the construction of the Lushan Tunnel,this study analyzed the factors affecting the quality of rock information acquisition during the construction period and the approximate range of the optimal timing of acquisition.We also conducted experiments on the concentration of respiratory dust and the concentration of total dust on each section of the Lushan Tunnel construction site and explored the optimal timing of acquiring rock information on the tunnel face by conducting several dust experiments at the construction site.The results showed that the best time to obtain information was before the erection of the steel arch,which was also the best time for the engineers to conduct mechanical characterization of the tunnel face and the lining inspection of the tunnel.The optimal acquisition timing identified in this study is crucial for improving the accuracy of rock information acquisition and guiding subsequent construction programs.展开更多
High-entropy alloy nanoparticles(HEA NPs)containing four or more elements possess several advantages over traditional alloy nanoparticles(NPs),such as higher strength,greater thermal stability,enhanced ox-idation resi...High-entropy alloy nanoparticles(HEA NPs)containing four or more elements possess several advantages over traditional alloy nanoparticles(NPs),such as higher strength,greater thermal stability,enhanced ox-idation resistance,stronger catalytic activity,and greater flexibility in adjusting element composition and composition ratio.However,the development of HEA NPs has been limited by preparation difficulties caused by the challenge of achieving complete miscibility between multiple-component elements and the unique high-entropy states.In this review,we provide a comprehensive summary of recent break-throughs in synthesizing and fabricating HEA NPs.We describe the experimental procedures and princi-ples of various synthesis methods,including furnace pyrolysis,carbothermal shock(CTS)method,pulse laser,solvothermal method,microwave heating,hydrogen spillover-driven,sputtering deposition,anneal-ing on mesoporous materials,arc discharge methods and using liquid metal.Additionally,we delve into recent improvements made to some of these methods or novel NPs synthesized using them.Finally,we review the current applications of HEA NPs and provide insights into potential applications of this rapidly emerging research field.展开更多
Photothermal conversion is one of the key technologies in solar energy collection,seawater desalination,photo thermal treatment and other important fields.In order to develop next generation photothermal materials,fou...Photothermal conversion is one of the key technologies in solar energy collection,seawater desalination,photo thermal treatment and other important fields.In order to develop next generation photothermal materials,four poly oxometalates,[(CH_(3))_(2)NH_(2)]_(12)H_(5)[Ni_(3)Mo_(18)O_(54)(HPO_(3))_(10)(PO_(4))]·_(18)H_(2)O(Compound 1),[(CH_(3))_(2)NH_(2)]_(1)Na_(11)[Ni_(2)Mo_(8)O_(22)(HPO_(3))_(10)]·16H_(2)O(Compound 2),Na_(15)(OH)_5[Mo_(6)O_(18)(HPO_(3))_(4)]_(2)[MoO]_(1.5)·16H_(2)O(Compound 3),[(CH_(3))_(2)NH_(2)]_(4)Na_(11)[Na[Mo_6O_(15)(HPO_(3))_(4)]_(2)]·_(18)H_(2)O(Compound 4),are successfully designed and synthesized via a micro wave-as sis ted reaction protocol.Compounds 1-4 not only exhibit broad absorption and notable photothermal conversion effects in near-infrared(NIR)region,but also have high photothermal conversion efficiencies and high quality NIR photothermal imaging effects under NIR laser irradiation.Compound 1 shows the best photothermal conversion effect,and it provides a unique model to explore the relationship between the complex metal oxide structure and photothermal conversion behavior at the molecular level.Both the experimental results and theoretical calculations consistently conclude that the charge and degree of electron delocalization on the Cluster have a robust influence on the photothermal conversion,as well as the aggregation microstructures.展开更多
High-lead solder joints are still playing an indispensable role in military and space applications.Nevertheless,in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain une...High-lead solder joints are still playing an indispensable role in military and space applications.Nevertheless,in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain unexplored.This research first performed aging tests on Sn10Pb90 solder joints,the shear strength at room and elevated temperatures gradually reduced,and the resistance increased.Here,a two-layered Ni-Sn intermetallic compound(IMC)structure was identified using transmission electron microscopy(TEM),which could be attributed to the change of Sn content in the solder.Moreover,the internal annealing twin of a Sn particle was discovered,which could be attributed to creeping induced by thermal expansion coefficient(CTE)difference between Sn and Pb.Detailed analysis of partial and whole annealing twins was conducted through high-resolution TEM(HRTEM).Finally,four degradation mechanisms were proposed.Thickening of the IMC layer would result in increased brittleness and resistivity.For particle coarsening,apart from diminishing the ductility and toughness of the solder joint,it would also accelerate the creeping rate by weakening the phase boundary strength.Regarding voids and cracks induced by phase boundary sliding,wedgeshaped cracking and pore-shaped cracking were discovered and their formation was analyzed.Most importantly,the consumption of Sn resulted in a depletion of wettable layer,leading to the formation of Pb streams and isolated IMC islands,also known as the spalling and delamination of IMCs.Pb diffusion followed a spiral path,which was mutually influenced by orientation misfit and concentration gradient.A technique to prevent cracking was proposed.This research is expected to provide significant technical references for high-lead solder joints.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
Due to the existence of oxide layer on the surface of Q235 steel,it is difficult to directly achieve metallurgical bonding with tin-lead al-loy,in order to solve this problem,this paper designed and successfully prepa...Due to the existence of oxide layer on the surface of Q235 steel,it is difficult to directly achieve metallurgical bonding with tin-lead al-loy,in order to solve this problem,this paper designed and successfully prepared steel surface activation liquid with the composition of 1 L distilled water,130 g ZnCl_(2),90 g NH_(4)Cl,5 mL 6501,and adding C_(3)H_(6)O_(3)to adjust pH 3.The results show that the activated mol-ten tin-lead alloy has a low wetting angle of 7.5°on the steel surface,which was then successfully plated on the steel surface by hot-dipping.The microstructural analysis of the plating-substrate interface and the thermodynamic calculation of the reaction can be found.The main structure of the interfacial reaction layer isα-Fe/FeSn_(2)/α-Pb+β-Sn.展开更多
Sn-based solder is a widely used interconnection material in the field of electronic packaging;however,the performance requirements for these solders are becoming increasingly demanding owing to the rapid development ...Sn-based solder is a widely used interconnection material in the field of electronic packaging;however,the performance requirements for these solders are becoming increasingly demanding owing to the rapid development in this area.In recent years,the addition of micro/nanoreinforcement phases to Sn-based solders has provided a solution to improve the intrinsic properties of the solders.This paper reviews the progress in Sn-based micro/nanoreinforced composite solders over the past decade.The types of reinforcement particles,preparation methods of the composite solders,and strengthening effects on the microstructure,wettability,melting point,mechanical properties,and corrosion resistance under different particle-addition levels are discussed and summarized.The mechanisms of performance enhancement are summarized based on material-strengthening effects such as grain refinement and second-phase dispersion strengthening.In addition,we discuss the current shortcomings of such composite solders and possible future improvements,thereby establishing a theoretical foundation for the future development of Sn-based solders.展开更多
In order to study the axial compression characteristics of brick masonry historical buildings, and to better protect and repair traditional mortar-brick masonry historical buildings, axial compression tests were carri...In order to study the axial compression characteristics of brick masonry historical buildings, and to better protect and repair traditional mortar-brick masonry historical buildings, axial compression tests were carried out on three kinds of restored mortar (pure mud mortar, pure mortar, and mud mortar) brick masonry with restored mortar brick masonry as the object of study. The damage modes, axial compression chemical indexes (compressive strength and elastic modulus), load-displacement curves and stress-strain curves of the three kinds of restored mortar brick masonry were obtained. The experimental results show that the compressive strength of mud mortar brick masonry of 1.676 MPa is better than that of pure mud 1.530 MPa and pure mortar 1.471 MPa brick masonry, which is due to the difference in the bond effect between the restored mortar material and the brick block. According to the test results, the compressive strength formula of the restored mortar brick masonry was modified, and the reasons for the difference between the experimental value of the modulus of elasticity of the restored mortar brick masonry and that of the traditional formula and the measured value were compared and analyzed by a factor of 6.73–7.1. Referring to the axial-pressure ontological relationship of the conventional brick masonry, the 4-parameter segmental function expression was proposed for the characterization of the stress-strain relationship of the restored mortar brick masonry with the use of the stress-strain normalization process. The research results provide theoretical support for the inheritance and development of traditional mortar brick masonry historical architecture.展开更多
Flame-retardant gel polymer electrolyte(FRGPE)with high ionic conductivity and practical safety is essential for the next generation of high energy density sodium metal batteries(SMBs).However,they suffer from serious...Flame-retardant gel polymer electrolyte(FRGPE)with high ionic conductivity and practical safety is essential for the next generation of high energy density sodium metal batteries(SMBs).However,they suffer from serious side reactions and insufficient interfacial stability against sodium metal anode,causing severe performance degradation and even safety issues.Herein,to address these challenges,a fluoroethylene carbonate(FEC)additive confined metal-organic framework(MOF)-based composite gel(AC-MCG)interlayer was constructed upon sodium anode through a facile in-situ UV-induced photopolymerization.The FEC confined in AC-MCG induces the formation of NaF-rich inorganic solid-electrolyte interphase,effectively eliminating the side reactions between the FRGPE and sodium metal anode.Moreover,the MOF with ordered nanochannels can homogenize Na^(+)flux during the plating process and also endow the AC-MCG interlayer with high mechanical strength,thus sufficiently suppressing the growth of sodium dendrites.Benefitting from these merits of the AC-MCG interlayer,a high critical current density of 2.0 mA cm^(-2)and a long-term cycling life for over 4200 h at 0.1 mA cm^(-2)are achieved for the Na/Na symmetric cells.Besides,the solid-state SMBs paired with the constructed AC-MCG interlayer also demonstrated considerable electrochemical performance and practical safety.展开更多
The challenge of low temperature and rapid diffusion bonding of a Ni-based superalloy was hereby addressed by using a Ni nano-coating and a spark plasma sintering(SPS).It successfully produced a Nibased superalloy joi...The challenge of low temperature and rapid diffusion bonding of a Ni-based superalloy was hereby addressed by using a Ni nano-coating and a spark plasma sintering(SPS).It successfully produced a Nibased superalloy joint with 337 MPa shear strength at 500℃ for 30 min,which is approximately 400℃ lower than the traditional hot pressure diffusion bonding(HPDB)temperature.The microstructure and mechanical properties of the joints were systematically investigated.It is revealed that the pulsed current and ultra-fine grains(19 nm)in the Ni nano-coating could significantly facilitate voids closure.The voids closure mechanisms involved(i)pulsed current strengthened plastic deformation,(ii)pulsed current strengthened surface source diffusion,(iii)pulsed current strengthened bonding interface diffusion,(iv)grain growth dividing the initial large voids into nano-voids,and(v)massive grain boundaries(GBs),lattice defects,and local high-temperature strengthened GBs diffusion.Furthermore,the GBs migration across the interface was investigated,and the results revealed that the GBs migration and fine grains(350 nm)near the bonding interface together increased the joint strength.展开更多
The rock mass rating(RMR)system is one of the most commonly used methods for classifying rock masses in underground engineering.Uncertainty of RMR values can signifi cantly aff ect the safety of underground projects.I...The rock mass rating(RMR)system is one of the most commonly used methods for classifying rock masses in underground engineering.Uncertainty of RMR values can signifi cantly aff ect the safety of underground projects.In this regard,we proposed a reliable rating approach for classifying rock masses based on the reliability theory.This theory was incorporated into the RMR system to establish the functions of rock masses of different classifications.By analyzing the probability distribution patterns of various parameters used in the RMR system and using the Monte Carlo method to calculate the reliability probability of surrounding rock belonging to each classifi cation,reliable RMR values for the rock mass to be excavated can be obtained.The results demonstrate that it is feasible to adopt the reliability theory in classifi cation tasks considering the randomness characteristics of rock and soil.As verified through a case study of the Lushan Tunnel project,the proposed approach can be used to obtain the probability of the uncertainty of the calculated RMR values of underground engineering rock masses,and the calculation results are consistent with reality.The proposed approach can serve as a reference for studies in other fi elds and also applies to other rock mass classifi cation methods.展开更多
Currently,perovskite solar cells have achieved commendable progresses in power conversion efficiency(PCE)and operational stability.However,some conventional laboratory-scale fabrication methods become challenging when...Currently,perovskite solar cells have achieved commendable progresses in power conversion efficiency(PCE)and operational stability.However,some conventional laboratory-scale fabrication methods become challenging when scaling up material syntheses or device production.Particularly,the prolonged high-temperature annealing process for the crystallization of perovskites requires a substantial amount of energy consumption and impact the modules’throughput.Here,we report a modified near-infrared annealing(NIRA)process,which involves the excess PbI_(2)engineered crystallization,efficiently reduces the preparation time for perovskite active layer to within 20 s compared to dozens of min in conventional hot plate annealing(HPA)process.The study showed that the incorporated PbI_(2)promoted the consistent nucleation of the perovskite film,leading to the subsequent rapid and homogeneous crystallization at the NIRA stage.Thus,highly crystalized perovskite film was realized with even better crystallization performance than conventional HPA-based film.Ultimately,efficient perovskite solar modules of 36 and 100 cm^(2)were readily fabricated with the optimal PCEs of 22.03%and 20.18%,respectively.This study demonstrates,for the first time,the successful achievement of homogeneous and high-quality crystallization in large-area perovskite films through rapid NIRA processing.This approach not only significantly reduces energy consumption during production,but also substantially shortens the manufacturing cycle,paving a new path toward the commercial-scale application of perovskite solar modules.展开更多
基金supported by the National Natural Science Foundation of China(No.42277256)the Natural Science Foundation of Hunan Province(No.2022JJ30710)+1 种基金Hunan Province Environmental Protection Research Program(No.HBKT-2021014)Guangdong Province Dabaoshan Mining Co.Ltd Technology Program(Semi-industrial test of 200T/time low-grade copper ore bio-heap leaching).
文摘The migration and transformation of hexavalent chromium(Cr(VI))in the environment are regulated by pyrite(FeS2).However,variations in pyrite crystal facets influence the adsorption behavior and electron transfer between pyrite and Cr(VI),thereby impacting the Cr(VI)reduction performance.Herein,two naturally common facets of pyritewere synthesized hydrothermally to investigate the facet-dependent mechanisms of Cr(VI)reduction.The experimental results revealed that the{111}facet exhibited approximately 1.30–1.50 times higher efficiency in Cr(VI)reduction compared to the{100}facet.Surface analyses and electrochemical results indicated that{111}facet displayed a higher iron-sulfur oxidation level,which was affected by its superior electrochemical properties during the reaction with Cr(VI).Density functional theory(DFT)calculations demonstrated that the narrower band gap and lower work function on{111}facet were more favorable for the electron transfer between Fe(II)and Cr(VI).Furthermore,different adsorption configurations were observed on{100}and{111}surfaces due to the unique arrangements of Fe and S atoms.Specifically,O atoms in Cr_(2)O_(7)^(2−)directly bound with the S sites on{100}but the Fe sites on{111}.According to the density of states(DOS),the Fe site had better reactivity than the S site in the reaction,which appeared to be related to the fracture of S-S bonds.Additionally,the adsorption configuration of Cr_(2)O_(7)^(2−)on{111}surface showed a stronger adsorption energy and a more stable coordination mode,favoring subsequent Cr(VI)reduction process.These findings provide an in-depth analysis of facet-dependent mechanisms underlying Cr(VI)reduction behavior,offering new insights into studying environmental interactions between heavy metals and natural minerals.
基金supported by the Natural Science Foundation of Hunan Province(No.2024JJ5419)the Hunan Provincial Key Research and Development Plan Project in 2024(No.2024JK2074)+2 种基金the Natural Science Foundation of Changsha(No.2023-197)the Open project of the Key Laboratory of digital flavor research of Hunan China Tobacco Industry Co.,Ltd(No.202143000834024)the Recruitment Program of Global Youth Experts.The authors also thank Shiyanjia Lab(www.shiyanjia.com)for the support of the UPS test.
文摘Multifunctional compatible stealth materials have emerged as the focal point of contemporary protection technology research and vanadium-based nanomaterials play a pivotal role in the development of advanced stealth materials.Here,a compatible stealth aerogel is successfully synthesized by employing mixed-valence decavanadate as the vanadium oxide(VO_(x))molecular model.Ultralight{VⅣVV_(9)}/MXene aerogel(0.0429 g cm^(-3))exhibits exceptional radar stealth performance with a minimal reflection loss(RL_(min))of−57.74 dB(99.9998%EMW absorption)and a significantly superior radar cross section reduction value of 26.77 dB m2.The aerogel’s exceptional properties,including a low infrared(IR)emissivity(0.479)and a low thermal conductivity of(32.30 mW m^(-1)K^(-1)),are crucial for enabling compatibility with IR and thermal stealth technologies.The presence of a mixed-valence polyoxovanadate cluster leads to an increase in the Schottky barrier and enhances magnetic properties,consequently boosting interfacial polarization and contributing to magnetic losses during electromagnetic wave(EMW)absorption.Consequently,altering the number of valence electrons significantly enhances the compatible stealth capabilities.These findings contribute significantly to our comprehension of how microstructure impacts EMW absorption processes and provide a basis for further research into the development of VO_(x)-based compatible stealth materials.
基金supported by the National Natural Science Foundation of China(Nos.U23A6005,22208112,and 32171721)the National Natural Science Foundation of China(No.22308109)+2 种基金Guangdong Basic and Applied Basic Research Foundation(No.2024A1515010678)the Fundamental Research Funds for the Central Universities(SCUT:2023ZYGXZR045)the State Key Laboratory of Pulp&Paper Engineering(Nos.2023ZD01,2023C02).
文摘Proton exchange membrane fuel cell(PEMFC)is a promising clean energy source,but its performance and stability are vulnerable to the negative effects of humidity conditions.The gas diffusion substrate(GDS)plays a pivotal role in regulating the moisture and gas transport.The single pore structure of traditionally designed GDS often leads to the pathway competition between moisture and gas,which effects the efficiency of fuel cells.In this study,we report on a hierarchical fibrous paper with tunable hierarchical pores for a sustainable GDS.This design offers gas permeability under wet conditions,by separating the gas pathway from the moisture pathway,thus mitigating their pathway competition.In addition,this paper forms a multi-scale scaffold that absorbs moisture under high humidity conditions and releases it under dry conditions.It is allowed to maintain an optimal internal humidity and further enhances the humidity adaptability.Furthermore,the carbon footprint is only 15.97%,significantly lower than commercial alternatives.This feature makes it a sustainable solution to stabilize PEMFCs under diverse humidity conditions.
基金Supported by the National Natural Science Foundation of China(No.42076126)the Shandong Key R&D Plan+2 种基金Major Scientific and Technological Innovation Project(No.2022CXGC020413)the Natural Science Foundation of Shandong Province(Nos.ZR2020MD072,ZR2021QD014)the Liaoning Provincial Natural Science Foundation:Joint Open Fund of the State Key Laboratory for the Creation and Development of New Pesticides(No.2022-KF-25-03)。
文摘The conversion process of chitin,one of the abundant biomass resources on the earth,not only follows the principles of green chemistry,but also has significant value in industrial applications.However,it is a great challenge to directly convert insoluble and rigid structured chitin to 5-hydroxymethylfurfural(HMF).To address this issue,we developed a green conversion process combining pretreatment and catalytic system.Chitin was first pretreated by hexafluoro isopropanol(HFIP),which somewhat disrupted the hydrogen bonding network within the chitin structure.Subsequently,formic acid(FA)and silicotungstic acid(STA)synergistically catalyzed the conversion to HMF in a biphasic system of 2-methyltetrahydrofuran(2-Me-THF)/H2O,and high yields(40.2%)HMF was obtained under the optimism conditions.The product distribution was analyzed by HPLC-MS and the co-catalysis of FA with STA was evidenced.A dual-function catalytic system with both Lewis and Br?nsted acids was created,the catalytic system that significantly improved the efficiency of complex tandem catalytic reactions with chitin.Based on the experimental results,a possible pathway for chitin conversion was deduced,providing a new catalytic idea for the efficient conversion of chitin to HMF.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.52205348 and 52275321)the Natural Science Foundation of Shandong Province(Grant Nos.ZR2023JQ021 and ZR2022QE087).
文摘Eutectic high-entropy alloys(EHEAs),combining the advantages of both eutectic alloys and high-entropy alloys(HEAs),possess good castability and superior comprehensive mechanical properties which are regarded as a revolutionary material system.In this paper,a current study of EHEAs is captured comprehensively for the first time,including basic theory,microstructure and deformation behavior,and alloy design.An in-depth analysis of the formation of different microstructures of EHEAs and their mechanical properties is presented,and four methods of designing EHEAs are summarized.Due to their unique characteristics,EHEAs show great potential in materials processing engineering.Here we give a comprehensive summary of their applications in welding,surface engineering,and additive manufacturing for the first time.Among them,EHEAs in welding are divided into three sections based on different welding techniques:fusion-based welding,solid-state welding,and diffusion reaction-based welding;EHEAs in surface engineering are separated into two parts:surface modification of bulk EHEAs and EHEA coatings;EHEAs in additive manufacturing are elaborated in two parts:laser powder bed fusion(LPBF)and laser direct energy deposition(LDED).Finally,a summary is given and a future outlook is prospected.
基金supported by the opening fund of National Key Research and Development Program of China(No.2020YFE0205300)Key Laboratory of Science and Technology on Silicon Devices,Chinese Academy of Sciences(No.KLSDTJJ2022-5)+1 种基金Chongqing Natural Science Foundation of China(No.cstc2021jcyj-msxmX1002)the Fundamental Research Funds for the Central Universities(No.AUGA5710051221).
文摘Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is critical for a microelectronic interconnection,will go through a phase transition at temperatures between 186 and 189℃.This research conducted an in-situ TEM study of a micro Cu/ENIG/Sn solder joint under isothermal aging test and proposed a model to illustrate the mechanism of the microstructural evolution.The results showed that part of the Sn solder reacted with Cu diffused from the electrode to formη´-Cu_(6)Sn_(5)during the ultrasonic bonding process,while the rest of Sn was left and enriched in a region in the solder joint.But the enriched Sn quickly diffused to both sides when the temperature reached 100℃,reacting with the ENIG coating and Cu to form(Ni_(x)Cu_(1-x))_(3)Sn_(4),AuSn_(4),and Cu_(6)Sn_(5)IMCs.After entering the heat preservation process,the diffusion of Cu from the electrode to the joint became more intense,resulting in the formation of Cu_(3)Sn.The scallop-type Cu_(6)Sn_(5)and the seahorse-type Cu_(3)Sn constituted a typical two-layered structure in the solder joint.Most importantly,the transition betweenηandη’was captured near the phase transition temperature for Cu_(6)Sn_(5)during both the heating and cooling process,which was accompanied by a volume shifting,and the transition process was further studied.This research is expected to serve as a reference for the service of micro Cu/ENIG/Sn solder joints in the electronic industry.
基金supported by the National Natural Science Foundation of China[Grant No.52079077]China Postdoctoral Science Foundation(Grant No.2022M711962)。
文摘Rapid acquisition of rock structure information during tunnel construction is crucial for optimizing subsequent construction strategies and avoiding engineering rock disasters.In this regard,this study proposes the best time to obtain rock structure information on the tunnel face during the construction period.By summarizing relevant studies on rock information acquisition locally and abroad and combining them with the actual situation during the construction of the Lushan Tunnel,this study analyzed the factors affecting the quality of rock information acquisition during the construction period and the approximate range of the optimal timing of acquisition.We also conducted experiments on the concentration of respiratory dust and the concentration of total dust on each section of the Lushan Tunnel construction site and explored the optimal timing of acquiring rock information on the tunnel face by conducting several dust experiments at the construction site.The results showed that the best time to obtain information was before the erection of the steel arch,which was also the best time for the engineers to conduct mechanical characterization of the tunnel face and the lining inspection of the tunnel.The optimal acquisition timing identified in this study is crucial for improving the accuracy of rock information acquisition and guiding subsequent construction programs.
基金National Key Research and Development Program of China(No.2020YFE0205300)Heilongjiang Provincial Natural Science Foundation of China(No.YQ2022E024)+1 种基金Chongqing Natural Science Foundation of China(No.cstc2021jcyj-msxmX1002)Fundamental Research Funds for the Central Universities(No.AUGA5710051221).
文摘High-entropy alloy nanoparticles(HEA NPs)containing four or more elements possess several advantages over traditional alloy nanoparticles(NPs),such as higher strength,greater thermal stability,enhanced ox-idation resistance,stronger catalytic activity,and greater flexibility in adjusting element composition and composition ratio.However,the development of HEA NPs has been limited by preparation difficulties caused by the challenge of achieving complete miscibility between multiple-component elements and the unique high-entropy states.In this review,we provide a comprehensive summary of recent break-throughs in synthesizing and fabricating HEA NPs.We describe the experimental procedures and princi-ples of various synthesis methods,including furnace pyrolysis,carbothermal shock(CTS)method,pulse laser,solvothermal method,microwave heating,hydrogen spillover-driven,sputtering deposition,anneal-ing on mesoporous materials,arc discharge methods and using liquid metal.Additionally,we delve into recent improvements made to some of these methods or novel NPs synthesized using them.Finally,we review the current applications of HEA NPs and provide insights into potential applications of this rapidly emerging research field.
基金financially supported by the Natural Science Foundation of Hunan Province(No.2020JJ4684)the Fundamental Research Funds for the Central Universities of Central South University(No.2021zzts0522)+1 种基金the Recruitment Program of Global Youth Expertsthe Open Project of the Key Laboratory of Digital Flavor Research of Hunan China Tobacco Industry Co.,Ltd(No.202143000834024)。
文摘Photothermal conversion is one of the key technologies in solar energy collection,seawater desalination,photo thermal treatment and other important fields.In order to develop next generation photothermal materials,four poly oxometalates,[(CH_(3))_(2)NH_(2)]_(12)H_(5)[Ni_(3)Mo_(18)O_(54)(HPO_(3))_(10)(PO_(4))]·_(18)H_(2)O(Compound 1),[(CH_(3))_(2)NH_(2)]_(1)Na_(11)[Ni_(2)Mo_(8)O_(22)(HPO_(3))_(10)]·16H_(2)O(Compound 2),Na_(15)(OH)_5[Mo_(6)O_(18)(HPO_(3))_(4)]_(2)[MoO]_(1.5)·16H_(2)O(Compound 3),[(CH_(3))_(2)NH_(2)]_(4)Na_(11)[Na[Mo_6O_(15)(HPO_(3))_(4)]_(2)]·_(18)H_(2)O(Compound 4),are successfully designed and synthesized via a micro wave-as sis ted reaction protocol.Compounds 1-4 not only exhibit broad absorption and notable photothermal conversion effects in near-infrared(NIR)region,but also have high photothermal conversion efficiencies and high quality NIR photothermal imaging effects under NIR laser irradiation.Compound 1 shows the best photothermal conversion effect,and it provides a unique model to explore the relationship between the complex metal oxide structure and photothermal conversion behavior at the molecular level.Both the experimental results and theoretical calculations consistently conclude that the charge and degree of electron delocalization on the Cluster have a robust influence on the photothermal conversion,as well as the aggregation microstructures.
基金financially supported by Chongqing Natural Science Foundation of China(No.cstc2021jcyjmsxmX1002)the Ministry of Industry and Information Technology of the People’s Republic of China(Nos.1GWZ2326032 and 302JC22123006)。
文摘High-lead solder joints are still playing an indispensable role in military and space applications.Nevertheless,in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain unexplored.This research first performed aging tests on Sn10Pb90 solder joints,the shear strength at room and elevated temperatures gradually reduced,and the resistance increased.Here,a two-layered Ni-Sn intermetallic compound(IMC)structure was identified using transmission electron microscopy(TEM),which could be attributed to the change of Sn content in the solder.Moreover,the internal annealing twin of a Sn particle was discovered,which could be attributed to creeping induced by thermal expansion coefficient(CTE)difference between Sn and Pb.Detailed analysis of partial and whole annealing twins was conducted through high-resolution TEM(HRTEM).Finally,four degradation mechanisms were proposed.Thickening of the IMC layer would result in increased brittleness and resistivity.For particle coarsening,apart from diminishing the ductility and toughness of the solder joint,it would also accelerate the creeping rate by weakening the phase boundary strength.Regarding voids and cracks induced by phase boundary sliding,wedgeshaped cracking and pore-shaped cracking were discovered and their formation was analyzed.Most importantly,the consumption of Sn resulted in a depletion of wettable layer,leading to the formation of Pb streams and isolated IMC islands,also known as the spalling and delamination of IMCs.Pb diffusion followed a spiral path,which was mutually influenced by orientation misfit and concentration gradient.A technique to prevent cracking was proposed.This research is expected to provide significant technical references for high-lead solder joints.
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.
基金supported by National Natural Science Foundation of China(Grant No.52305353)Postdoctoral Science Foundation of China(Grant No.2023M7408938).
文摘Due to the existence of oxide layer on the surface of Q235 steel,it is difficult to directly achieve metallurgical bonding with tin-lead al-loy,in order to solve this problem,this paper designed and successfully prepared steel surface activation liquid with the composition of 1 L distilled water,130 g ZnCl_(2),90 g NH_(4)Cl,5 mL 6501,and adding C_(3)H_(6)O_(3)to adjust pH 3.The results show that the activated mol-ten tin-lead alloy has a low wetting angle of 7.5°on the steel surface,which was then successfully plated on the steel surface by hot-dipping.The microstructural analysis of the plating-substrate interface and the thermodynamic calculation of the reaction can be found.The main structure of the interfacial reaction layer isα-Fe/FeSn_(2)/α-Pb+β-Sn.
基金financially supported by the State Key Laboratory for Mechanical Behavior of Materials,China(No.202325012)the National Natural Science Foundation of China(No.U21A20128).
文摘Sn-based solder is a widely used interconnection material in the field of electronic packaging;however,the performance requirements for these solders are becoming increasingly demanding owing to the rapid development in this area.In recent years,the addition of micro/nanoreinforcement phases to Sn-based solders has provided a solution to improve the intrinsic properties of the solders.This paper reviews the progress in Sn-based micro/nanoreinforced composite solders over the past decade.The types of reinforcement particles,preparation methods of the composite solders,and strengthening effects on the microstructure,wettability,melting point,mechanical properties,and corrosion resistance under different particle-addition levels are discussed and summarized.The mechanisms of performance enhancement are summarized based on material-strengthening effects such as grain refinement and second-phase dispersion strengthening.In addition,we discuss the current shortcomings of such composite solders and possible future improvements,thereby establishing a theoretical foundation for the future development of Sn-based solders.
基金funded by National Key R&D Program of China(No.2022YFC3803500).
文摘In order to study the axial compression characteristics of brick masonry historical buildings, and to better protect and repair traditional mortar-brick masonry historical buildings, axial compression tests were carried out on three kinds of restored mortar (pure mud mortar, pure mortar, and mud mortar) brick masonry with restored mortar brick masonry as the object of study. The damage modes, axial compression chemical indexes (compressive strength and elastic modulus), load-displacement curves and stress-strain curves of the three kinds of restored mortar brick masonry were obtained. The experimental results show that the compressive strength of mud mortar brick masonry of 1.676 MPa is better than that of pure mud 1.530 MPa and pure mortar 1.471 MPa brick masonry, which is due to the difference in the bond effect between the restored mortar material and the brick block. According to the test results, the compressive strength formula of the restored mortar brick masonry was modified, and the reasons for the difference between the experimental value of the modulus of elasticity of the restored mortar brick masonry and that of the traditional formula and the measured value were compared and analyzed by a factor of 6.73–7.1. Referring to the axial-pressure ontological relationship of the conventional brick masonry, the 4-parameter segmental function expression was proposed for the characterization of the stress-strain relationship of the restored mortar brick masonry with the use of the stress-strain normalization process. The research results provide theoretical support for the inheritance and development of traditional mortar brick masonry historical architecture.
基金supported by the National Natural Science Foundation of China(No.52203261,No.52473213)the China Postdoctoral Science Foundation(2023731330)the Central Laboratory,School of Chemical and Material Engineering,Jiangnan University。
文摘Flame-retardant gel polymer electrolyte(FRGPE)with high ionic conductivity and practical safety is essential for the next generation of high energy density sodium metal batteries(SMBs).However,they suffer from serious side reactions and insufficient interfacial stability against sodium metal anode,causing severe performance degradation and even safety issues.Herein,to address these challenges,a fluoroethylene carbonate(FEC)additive confined metal-organic framework(MOF)-based composite gel(AC-MCG)interlayer was constructed upon sodium anode through a facile in-situ UV-induced photopolymerization.The FEC confined in AC-MCG induces the formation of NaF-rich inorganic solid-electrolyte interphase,effectively eliminating the side reactions between the FRGPE and sodium metal anode.Moreover,the MOF with ordered nanochannels can homogenize Na^(+)flux during the plating process and also endow the AC-MCG interlayer with high mechanical strength,thus sufficiently suppressing the growth of sodium dendrites.Benefitting from these merits of the AC-MCG interlayer,a high critical current density of 2.0 mA cm^(-2)and a long-term cycling life for over 4200 h at 0.1 mA cm^(-2)are achieved for the Na/Na symmetric cells.Besides,the solid-state SMBs paired with the constructed AC-MCG interlayer also demonstrated considerable electrochemical performance and practical safety.
基金financially supported by the National Nat-ural Science Foundation of China(Nos.U22A20185,52175302,and U21A20128)the National MCF Energy R&D Program(No.2019YFE03100100)the Fundamental Research Funds for the Central Universities(No.2022FRFK060009).
文摘The challenge of low temperature and rapid diffusion bonding of a Ni-based superalloy was hereby addressed by using a Ni nano-coating and a spark plasma sintering(SPS).It successfully produced a Nibased superalloy joint with 337 MPa shear strength at 500℃ for 30 min,which is approximately 400℃ lower than the traditional hot pressure diffusion bonding(HPDB)temperature.The microstructure and mechanical properties of the joints were systematically investigated.It is revealed that the pulsed current and ultra-fine grains(19 nm)in the Ni nano-coating could significantly facilitate voids closure.The voids closure mechanisms involved(i)pulsed current strengthened plastic deformation,(ii)pulsed current strengthened surface source diffusion,(iii)pulsed current strengthened bonding interface diffusion,(iv)grain growth dividing the initial large voids into nano-voids,and(v)massive grain boundaries(GBs),lattice defects,and local high-temperature strengthened GBs diffusion.Furthermore,the GBs migration across the interface was investigated,and the results revealed that the GBs migration and fine grains(350 nm)near the bonding interface together increased the joint strength.
基金supported by the National Natural Science Foundation of China [Grant No.52079077]China Postdoctoral Science Foundation (Grant No. 2022M711962)。
文摘The rock mass rating(RMR)system is one of the most commonly used methods for classifying rock masses in underground engineering.Uncertainty of RMR values can signifi cantly aff ect the safety of underground projects.In this regard,we proposed a reliable rating approach for classifying rock masses based on the reliability theory.This theory was incorporated into the RMR system to establish the functions of rock masses of different classifications.By analyzing the probability distribution patterns of various parameters used in the RMR system and using the Monte Carlo method to calculate the reliability probability of surrounding rock belonging to each classifi cation,reliable RMR values for the rock mass to be excavated can be obtained.The results demonstrate that it is feasible to adopt the reliability theory in classifi cation tasks considering the randomness characteristics of rock and soil.As verified through a case study of the Lushan Tunnel project,the proposed approach can be used to obtain the probability of the uncertainty of the calculated RMR values of underground engineering rock masses,and the calculation results are consistent with reality.The proposed approach can serve as a reference for studies in other fi elds and also applies to other rock mass classifi cation methods.
基金supported by China Huaneng Group Key R&D Program(HNKJ22-H104)the Science and Technology Programs of Fujian Province(2022H0005)+1 种基金the Fundamental Research Funds for the Central Universities(20720240067)Technology Projects of Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(RD2020020101 and RD2022040601).
文摘Currently,perovskite solar cells have achieved commendable progresses in power conversion efficiency(PCE)and operational stability.However,some conventional laboratory-scale fabrication methods become challenging when scaling up material syntheses or device production.Particularly,the prolonged high-temperature annealing process for the crystallization of perovskites requires a substantial amount of energy consumption and impact the modules’throughput.Here,we report a modified near-infrared annealing(NIRA)process,which involves the excess PbI_(2)engineered crystallization,efficiently reduces the preparation time for perovskite active layer to within 20 s compared to dozens of min in conventional hot plate annealing(HPA)process.The study showed that the incorporated PbI_(2)promoted the consistent nucleation of the perovskite film,leading to the subsequent rapid and homogeneous crystallization at the NIRA stage.Thus,highly crystalized perovskite film was realized with even better crystallization performance than conventional HPA-based film.Ultimately,efficient perovskite solar modules of 36 and 100 cm^(2)were readily fabricated with the optimal PCEs of 22.03%and 20.18%,respectively.This study demonstrates,for the first time,the successful achievement of homogeneous and high-quality crystallization in large-area perovskite films through rapid NIRA processing.This approach not only significantly reduces energy consumption during production,but also substantially shortens the manufacturing cycle,paving a new path toward the commercial-scale application of perovskite solar modules.
