Magnesium alloys have emerged as promising light weight materials due to their low density,high specific strength,excellent machinability,and superior damping capacity,making them ideal for aerospace,automotive,and el...Magnesium alloys have emerged as promising light weight materials due to their low density,high specific strength,excellent machinability,and superior damping capacity,making them ideal for aerospace,automotive,and electronics applications.However,broader use of magnesium alloys is limited by poor thermo-mechanical performance,corrosion susceptibility,and low formability at room temperature.The addition of rare-earth elements such as gadolinium,yttrium,and neodymium has meaningfully improved these limitations,enhancing the overall performance of magnesium alloys.This review highlights recent advancements in rare-earth magnesium alloys,focusing on their improved thermo-mechanical properties,microstructural evolution,crystallization behavior,and texture development.Herein,strengthening mechanisms associated with rare-earth additions are discussed in detail.Furthermore,the article explores growing relevance of these alloys in advanced applications,including biomedical implants,Io T devices,aerospace structures,defense systems,and general engineering.With their enhanced mechanical and functional properties,rare-earth magnesium alloys represent a new generation of high-performance,functional materials poised to drive innovation across multiple technology sectors.展开更多
Carbon fiber reinforced silicon carbide ceramic composite(C/SiC)has become a key structural material due to its excellent high temperature resistance,corrosion resistance and oxidation resistance.However,C/SiC composi...Carbon fiber reinforced silicon carbide ceramic composite(C/SiC)has become a key structural material due to its excellent high temperature resistance,corrosion resistance and oxidation resistance.However,C/SiC composites are prone to oxidation under long-term high temperature loading conditions.In this work,the research progress of SiC coating and its modified coating on the surface of C/SiC composite is reviewed.The optimization of these coatings mainly involves two aspects:structure and composition.The focus of structural optimization is to improve the interphase structure by such as SiC nanowires,thereby improving the interfacial bonding strength between the coatings and between the coatings and the substrate.The focus of composition optimization is to improve the performance of the coatings under high temperature loads by rare earth silicates,etc.The modification strategies of various modified coatings are emphatically introduced,which is helpful to guide the preparation of high-performance C/SiC coating materials in the future.展开更多
Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis.Herein,porous Ti Fe2intermetallics were fabricated by the reactive synthesis of elemental powders.The...Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis.Herein,porous Ti Fe2intermetallics were fabricated by the reactive synthesis of elemental powders.The phase transformation and pore formation of porous TiFe2intermetallics were investigated,and its corrosion behavior and hydrogen evolution reaction(HER)performance in alkali solution were studied.Porous TiFe2intermetallics with porosity in the range of 34.4%-56.4%were synthesized by the diffusion reaction of Ti and Fe elements,and the pore formation of porous TiFe2intermetallic compound is the result of a combination of the bridging effect and the Kirkendall effect.The porous TiFe2samples exhibit better corrosion resistance compared with porous 316L stainless steel,which is related to the formation of uniform nanosheets on the surface that hinder further corrosion,and porous TiFe2electrode shows the overpotential of 220.6 and 295.6 mV at 10 and 100 mA·cm-2,suggesting a good catalytic performance.The synthesized porous Fe-based intermetallic has a controllable pore structure as well as excellent corrosion resistance,showing its potential in the field of filtration and separation.展开更多
The present study introduces a screw-pressing charging method to tackle deficiencies in automation and charge uniformity during the melt-casting of polymer-based energetic materials.To ensure the safety of the experim...The present study introduces a screw-pressing charging method to tackle deficiencies in automation and charge uniformity during the melt-casting of polymer-based energetic materials.To ensure the safety of the experiments,this study used inert materials with similar physical properties to partially substitute for the actual energetic components in the preparation of simulant materials.By thoroughly analyzing slurry physical properties,a simulation framework and an extensive performance evaluation method were developed.Such tools guide the design of the structure and configuration of process parameters.Results demonstrate that employing the Pin element significantly enhances radial mixing within the screw,minimizes temperature variations in the slurry,and improves both efficiency and safety in the mixing process.Further,adjustments such as widening the cone angle of the barrel,modifying the solid content of the slurry,and varying the speed of the screw can optimize the mechanical and thermal coupling in the flow field.These adjustments promote higher-quality slurry and create a safer production environment for the extrusion process.展开更多
The hot compression curves and deformed microstructures were investigated under various hot deformation conditions in three states:hot isostatic pressing(HIP,A1),HIP+hot extrusion at 1100℃(A2),and HIP+hot extrusion a...The hot compression curves and deformed microstructures were investigated under various hot deformation conditions in three states:hot isostatic pressing(HIP,A1),HIP+hot extrusion at 1100℃(A2),and HIP+hot extrusion at 1150℃(A3).The results show that A2 sample,extruded at 1100℃ with uniform γ+γ′duplex microstructures,demonstrates excellent hot deformation behavior at both 1050 and 1100℃.The true stress-true strain curves of A2 sample maintain a hardening-softening equilibrium over a larger strain range,with post-deformation average grain size of 5μm.The as-HIPed A1 sample and 1150℃ extruded A3 sample exhibit a softening region in deformation curves at 1050℃,and the grain microstructures reflect an incomplete recrystallized state,i.e.combination of fine recrystallized grains and initial larger grains,characterized by a necklace-like microstructure.The predominant recrystallization mechanism for these samples is strain-induced boundary migration.At 1150℃ with a strain rate of 0.001 s^(-1),the influence of the initial microstructure on hot deformation behavior and resultant microstructure is relatively less pronounced,and postdeformation microstructures are fully recrystallized grains.Fine-grained microstructures are conducive to maximizing the hot deformation potential of alloy.By judiciously adjusting deformation regimes,a fine and uniform deformed microstructure can be obtained.展开更多
The microstructure of single crystal superalloy is relatively simple,consisting primarily ofγdendrites andγ/γ′eutectics.During the directional solidification process of Ni-based single crystal superalloys,withdraw...The microstructure of single crystal superalloy is relatively simple,consisting primarily ofγdendrites andγ/γ′eutectics.During the directional solidification process of Ni-based single crystal superalloys,withdrawal rate is a critical parameter affecting the spatial distribution ofγ/γ′eutectic along gravity direction.The results show that theγ/γ′eutectic fraction of the upper platform surface is always higher than that of the lower one,regardless of withdrawal rate.As the withdrawal rate decreases,there is a significant increase inγ/γ′eutectic fraction on the upper surface,while it decreases on the lower surface.The upward accumulation ofγ/γ′eutectic becomes more severe as the withdrawal rate decreases.It is also found that the percentage of Al+Ta is positively correlated with theγ/γ′eutectic fraction.Thermo-solute convection of Al and Ta solutes in the solidification front is the prime reason for the non-uniform distribution of eutectic.The non-uniform distribution ofγ/γ′eutectic cannot be eliminated even after subsequent solution heat treatment,resulting in excess eutectic on the upper surface and thus leading to the scrapping of the blade.展开更多
The present investigation introduces a composite frequency selective Rasorber(CFSR)that demonstrates a wide−1 dB transmission band,two high absorption bands with absorptivity higher than 90%,and large oblique incidenc...The present investigation introduces a composite frequency selective Rasorber(CFSR)that demonstrates a wide−1 dB transmission band,two high absorption bands with absorptivity higher than 90%,and large oblique incidence angles up to 60°.The CFSR consists of four functional layers separated by three dielectric slabs,which includes lossless metasurface-Ⅰ(MS-Ⅰ),loss metasurface-Ⅱ(MS-Ⅱ),loss metasurface-Ⅲ(MS-Ⅲ),and a three-dimensional metastructure(3D-MS).MS-Ⅰfunctions as a reflector for two absorption bands with a minimal insertion loss transmission window.MS-Ⅱis designed for high-frequency absorption.MS-Ⅲserves as a low-frequency absorption layer for CFSR and an impedance matching layer for MS-Ⅱ.The design methodologies for the transmission window in MS-III and the introduction of 3D-MS are key to achieving high-performance CFSR.The physical mechanisms of CFSR are explained through equivalent circuit model(ECM)analysis and impedance characterization.Finally,measurement results confirm that the proposed CFSR exhibits a−1 dB transmission band ranging from 8.79 to 10.41 GHz with a minimum insertion loss of 0.44 dB at 9.59 GHz;furthermore,the frequency range where reflection coefficient remains below−10 dB is measured to be between 3.33 and 18.00 GHz,aligning well with simulation outcomes.展开更多
The durability performance in molten aluminum with high chemical activity is considered to be a crucial factor for the application of traditional ceramicmatrix composites in the aluminum industry.Herein,novel Ti(C,N)c...The durability performance in molten aluminum with high chemical activity is considered to be a crucial factor for the application of traditional ceramicmatrix composites in the aluminum industry.Herein,novel Ti(C,N)cermet composites with excellent corrosion resistance,featuring distinct ratios of high-entropy alloy binders,were meticulously synthesized by spark plasma sintering(SPS).The synergetic effect of porosity and binder on the corrosion resistance was detailed analyzed.The results show that 8 wt%binder provides an optimum balance of porosity,hardness,fracture toughness and corrosion resistance of the cermets.The appealing corrosion resistance is intimately associated with the formation of a continuous layer consisting of Ti N/Al N,which is introduced through the decarburization of the Ti(C,N)cermets.Additionally,a corrosion mechanism is proposed to elucidate the formation of alternating morphologies within the reaction layers of the cermets.This work is beneficial for selecting structural materials for use in the aluminum industry.展开更多
The selective reduction of carbon dioxide(CO_(2))into high-value-added chemicals is one of the most effective means to solve the current energy and environmental problems,which could realize the utilization of CO_(2) ...The selective reduction of carbon dioxide(CO_(2))into high-value-added chemicals is one of the most effective means to solve the current energy and environmental problems,which could realize the utilization of CO_(2) and promote the balance of the carbon cycle.Formate is one of the most economical and practical products of all the electrochemical CO_(2) reduction products.Among the many metal-based electrocatalysts that can convert CO_(2) into formate,Sn-based catalysts have received a lot of attention because of their low-cost,non-toxic characteristics and high selectivity for formate.In this article,the most recent development of Sn-based electrocatalysts is comprehensively summarized by giving examples,which are mainly divided into monometallic Sn,alloyed Sn,Sn-based compounds and Sn composite catalysts.Finally,the current performance enhancement strategies and future directions of the field are summarized.展开更多
Iron disulfide(FeS_(2))has been widely used in thermal batteries because of its high theoretical specific capacity and voltage plateau.However,low thermal decomposition temperature,poor conductivity and inferior actua...Iron disulfide(FeS_(2))has been widely used in thermal batteries because of its high theoretical specific capacity and voltage plateau.However,low thermal decomposition temperature,poor conductivity and inferior actual specific capacity limit its wide applications.Herein,we report a gold-doped FeS_(2)(FeS_(2)-Au),which not only reduces the band gap of the FeS_(2)crystals but also enriches the electron transport path of FeS_(2)by the formation of Au nanoparticles.First-principles calculation shows that the diffusion energy barrier of lithium-ion is reduced after the Au-doped FeS_(2).In addition,Au increases the electron cloud density around sulfur atoms,which helps to enhance the stability of Fe-S covalent bonds and thus results in better thermal stability of FeS_(2).When the Au content is 130μg·g^(-1)(FeS_(2)-Au_(4)),the thermal decomposition temperature(TG5%)of FeS_(2)-Au is 72.2℃ higher than that of pristine FeS_(2).At a discharge temperature of 500℃,a current density of 200 mA·cm^(-2) and a cutoff voltage of 1.4 V,FeS_(2)-Au_(4)demonstrates superior specific capacity and high specific energy compared to FeS_(2).More precisely,the specific capacity of FeS_(2)-Au_(4)attains a value of 379 mAh·g^(-1),with a corresponding specific energy of 714 Wh·kg^(-1).In contrast,the discharge specific capacity and specific energy of FeS_(2)are lower,amounting to 348 mAh·g^(-1)and 656 Wh·kg^(-1),respectively.This study offers a novel approach to enhancing the electrochemical performance of FeS_(2)in high-temperature molten salt electrochemical systems(thermal batteries),thereby laying a solid foundation for its potential practical application.展开更多
Removing copper from nickel electrolysis anode solution has been a major keypoint in the nickel metallurgy industry.In this study,we proposed a novel process flow to promote removing copper from nickel electrolysis an...Removing copper from nickel electrolysis anode solution has been a major keypoint in the nickel metallurgy industry.In this study,we proposed a novel process flow to promote removing copper from nickel electrolysis anode solution.A simulated nickel anode solution was designed,and static and dynamic adsorption experiments were conducted to determine the best of solution pH,adsorption time and temperature,resin dosage and particle size,and stirring speed.The optimal conditions were explored for copper removal from nickel electrolysis anode solution.Based on the optimal experimental conditions and the relevant experimental data,a novel process for copper removal from nickel electrolysis anodes was designed and verified.This novel process of copper removal from nickel electrolysis anodes was confirmed with nickel anolyte solution with nickel 50−60 g/L and copper 0.5 g/L.After finishing the novel process of copper removal,the nickel in the purified nickel anolyte became undetectable and copper concentration was 3 mg/L,the novel process of resin adsorption to remove copper from nickel anode solution through static and dynamic adsorptions has an efficacious copper removal.It is a beneficial supplement to traditional methods.展开更多
Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by ad...Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by adding carboxyl-modified silica(C-SiO2),PAA,and CaCl_(2) to achieve higher viscosity over 25℃.The rheological behavior of C-SiO_(2)-based shear thickening fluid(CS-STF)was investigated at a temperature range of 25–55℃.Unlike SiO_(2)-based STF,which exhibits single-step thickening and a negative correlation between viscosity and temperature.As the C-SiO_(2) content was 41%(w/w)and the mass ratio of PAA:CaCl_(2):C-SiO_(2) was 3:1:10,the CS-STF displayed a double-thickening behavior,and the peak viscosity reached 1330 Pa·s at 35℃.From the yarn pull-out test,the inter-yarn force was significantly increased with the increasing CS-STF content.Treating UHMWPE fabrics with CS-STF improved the impact resistance effectively.In the blunt impact test,the U-CS fabrics with high CS-STF content(121.45 wt%)experienced penetration failure under high impact energy(18 J)due to stress concentration caused by the shear thickening behavior.The knife stabbing test demonstrated that U-CS fabrics with appropriate content(88.38 wt%)have the best stabbing resistance in various impact energies.Overall,this study proposed a high-performence STF showing double-thickening and enhancing shear-thickening behavior at a wide temperature range,the composite fabrics with the performance of resisting both the blunt and stab impact had broad application prospects in the field of personal protection.展开更多
The mechanical properties and oxidation resistance of two nickel-based superalloys with and without oxide dispersion strengthened(ODS)phases at different temperatures were studied.The microstructure was investigated b...The mechanical properties and oxidation resistance of two nickel-based superalloys with and without oxide dispersion strengthened(ODS)phases at different temperatures were studied.The microstructure was investigated by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).The results show that the yield strength of the samples with and without ODS phases at room temperature is 1020 and 324 MPa,respectively.The yield strength model was constructed,and it is found that the contribution of grain boundary strengthening,dislocation strengthening and nanoparticle strengthening of nickel-based ODS superalloy exceeds 83%.As the temperature increases,grain boundary sliding and migration decrease the strength of sample but improve its ductility.Oxidation hinders the ductility of sample and intensifies its fracture,and the maximum elongation of nickel-based ODS superalloy at 800℃ is 47.3%.展开更多
The reduction of global carbon emissions and the achievement of carbon neutrality have become the focus of addressing climate change and global warming.Electrochemical CO_(2) reduction(CO_(2)RR),as a technology that c...The reduction of global carbon emissions and the achievement of carbon neutrality have become the focus of addressing climate change and global warming.Electrochemical CO_(2) reduction(CO_(2)RR),as a technology that can efficiently convert CO_(2) into value-added products,is receiving widespread attention.This article reviews the current research status of Cu/metal oxide heterostructures in the field of electrochemical reduction of CO_(2).The review first introduces the importance of electrochemical reduction of CO_(2) and the application potential of Cu/metal oxide heterostructures in this field.Subsequently,a comprehensive discussion is presented on the exploration of various Cu/metal oxide heterostructures and their corresponding structure-performance relationship,with particular emphasis on the catalysts'activity,selectivity,stability and the nature of active sites.Lastly,the review provides an overview of the current research challenges and future development trends in this field.展开更多
A process of purification of coal-based coke powder as anode the treatment of coke powder with dilute hydrofluoric acid solution, for Li-ion batteries was attempted. The process started with followed by united-acid-le...A process of purification of coal-based coke powder as anode the treatment of coke powder with dilute hydrofluoric acid solution, for Li-ion batteries was attempted. The process started with followed by united-acid-leaching using sulfuric acid and hydrochloric acid. The effects of altering the hydrofluoric acid addition, hydrofluoric acid concentration, contact time, temperature and acid type were investigated. A minimum ash content of 0.35% was obtained when proper conditions were applied. The electrochemical performance of purified coke powder shows greatly improved electrochemical performance. The as-purified coke powder presented an initial reversible capacity of 257.4 mAh/g and a retention rate of 95% after 50 cycles. The proposed purification process paves a way to prepare a promising anode material with good performance with low cost of coke powder for Li-ion batteries.展开更多
In this study,the selective laser melting(SLM)technology has been employed to manufacture a nickelbased superalloy which was conventionally prepared through powder metallurgy(PM)route.The microstructural features and ...In this study,the selective laser melting(SLM)technology has been employed to manufacture a nickelbased superalloy which was conventionally prepared through powder metallurgy(PM)route.The microstructural features and defects were systematically investigated both prior to and after heat treatment and compared with the PM counterpart.Both solidification cracking and liquation cracking were observed in the SLM specimen in which the grain misorientation and low melting point(γ+γ')eutectic played a vital role in their formation mechanism.Columnar grains oriented along building direction were ubiquitous,corresponding to strong<001>fiber texture.Solidification cell structures and melt pools are pervasive and noγ'precipitates were detected at about 10 nm scale before heat treatment.After supersolvus solution and two-step aging treatments,high volume fractionγ'precipitates emerged and their sizes and morphologies were comparable to those in PM alloy.<001>texture is relieved and columnar grains tend to become more equiaxed due to static recrystallization process and grain boundary migration events.Significant annealing twins formed in SLM alloy and are clarified as a consequence of recrystallization.Our results provide fundamental understandings for the SLM PM nickel-based superalloy both before and after heat treatment and demonstrate the potential to fabricate this group of alloys using SLM technology.展开更多
Effects of metal (Ni, Cu, Al) and composite metal (NiB, NiCu, NiCuB) nanopowders on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellant ammonium perchlorate/hydroxyterminated polybuta...Effects of metal (Ni, Cu, Al) and composite metal (NiB, NiCu, NiCuB) nanopowders on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellant ammonium perchlorate/hydroxyterminated polybutadiene (AP/HTPB) were studied by thermal analysis (DTA). The results show that metal and composite metal nanopowders all have good catalytic effects on the thermal decomposition of AP and AP/HTPB composite solid propellant. The effects of metal nanopowders on the thermal decomposition of AP are less than those of the composite metal nanopowders. The effects of metal and composite metal nanopowders on the thermal decomposition of AP are different from those on the thermal decomposition of the AP/HTPB composite solid propellant.展开更多
Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating ...Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating combustion, the desired nanocrystalline perovskite LaMnO3 was obtained and no further calcination was carried out. The possible processes of combustion reaction were discussed according to the principle of propellant chemistry. The autocombustion and thermal decomposition of the precursor were investigated using the TG-DTA and FT-IR techniques. The influences of glycine-nitrate molar ratio and heat-treatment temperature on the perovskite phase formation and crystallite size of as-burnt powder were studied by XRD. The morphology and size of the as-burnt powder before and after milling were characterized and compared by TEM.展开更多
The effects of size distribution,morphology and volume fraction ofγ′phase and grain size on tensile properties of powder processed Ni-based superalloy were investigated by using two different quenching methods.Oil q...The effects of size distribution,morphology and volume fraction ofγ′phase and grain size on tensile properties of powder processed Ni-based superalloy were investigated by using two different quenching methods.Oil quenching and air cooling were adopted with cooling rate of 183°C/s and 4?15°C/s,respectively.The experimental results show that the average size of the secondaryγ′after oil quenching is 24.5 nm compared with 49.8 nm under air cooling,and corresponding volume fractions ofγ′are 29%and 34%,respectively.Meanwhile,the average grain size remains nearly equivalent from both oil-quenching and air-cooling specimens.The tensile strength at room temperature is higher for the oil-quenched specimen than the equivalent from the air-cooled specimen,but the difference approaches each other as the temperature increases to 650°C.The fractography clearly demonstrates that transgranular fracture governs the failure process at ambient temperature,in contrast to the intergranular fracture at 650°C or even higher temperature.These two mechanical responses indicate the strengthening effects ofγ′precipitates and grain boundary for polycrystalline Ni-based superalloys at different temperatures.展开更多
With the rapid development of indium tin oxide(ITO)in the electronic display industry,choosing which raw powders to prepare high-quality ITO targets has always been a controversial topic.In the work,in order to clearl...With the rapid development of indium tin oxide(ITO)in the electronic display industry,choosing which raw powders to prepare high-quality ITO targets has always been a controversial topic.In the work,in order to clearly understand the effect of the raw powders on the microstructure and properties of ITO targets and thin films,tin-doped indium oxide(dITO)and In_(2)O_3-SnO_(2)mixed(mITO)powders were chosen to prepare ITO targets for depositing the films and a comparative study on their microstructure and properties was conducted.It is found that,(1)dITO targets possess a higher solid solubility of tin in indium oxide and more uniform elemental distribution,while there are a higher density,a finer grain size and a higher mass ratio of In_(2)O_3 to SnO_(2)for the mITO targets;(2)dITO films with more coarser columnar grains and a rougher surface prefer to grow along the[100]direction in an Ar atmosphere;(3)the conductive property of ITO films only depends on the doping amount of tin and is independent of the raw powders and the preparation process of the target source;(4)dITO films possess the superior optical property and narrower optical band gap;(5)the etching property of mITO films is superior to that of dITO films due to the lower solid solubility of tin in indium oxide.展开更多
基金the support of the SPARC project(P3808)UKIERI-4 Strand 1 Institutional Research&Mobility Partnerships Grant(45580615 UKIERISPARC/01/18)under the Indo-UK schemeSKT extends heartfelt gratitude to Nitte University for providing the research grant(grant no.NUFR-23-070)。
文摘Magnesium alloys have emerged as promising light weight materials due to their low density,high specific strength,excellent machinability,and superior damping capacity,making them ideal for aerospace,automotive,and electronics applications.However,broader use of magnesium alloys is limited by poor thermo-mechanical performance,corrosion susceptibility,and low formability at room temperature.The addition of rare-earth elements such as gadolinium,yttrium,and neodymium has meaningfully improved these limitations,enhancing the overall performance of magnesium alloys.This review highlights recent advancements in rare-earth magnesium alloys,focusing on their improved thermo-mechanical properties,microstructural evolution,crystallization behavior,and texture development.Herein,strengthening mechanisms associated with rare-earth additions are discussed in detail.Furthermore,the article explores growing relevance of these alloys in advanced applications,including biomedical implants,Io T devices,aerospace structures,defense systems,and general engineering.With their enhanced mechanical and functional properties,rare-earth magnesium alloys represent a new generation of high-performance,functional materials poised to drive innovation across multiple technology sectors.
基金The authors would like to thank the National Key Research and Development Program of China(No.2021YFB3703800)the National Natural Science Foundation of China(No.52075555)the Hunan Provincial Intelligent Agricultural Machinery Equipment Innovation Project in 2023 by Hunan Provincial Department of Agriculture and Rural,China,for their financial support.
文摘Carbon fiber reinforced silicon carbide ceramic composite(C/SiC)has become a key structural material due to its excellent high temperature resistance,corrosion resistance and oxidation resistance.However,C/SiC composites are prone to oxidation under long-term high temperature loading conditions.In this work,the research progress of SiC coating and its modified coating on the surface of C/SiC composite is reviewed.The optimization of these coatings mainly involves two aspects:structure and composition.The focus of structural optimization is to improve the interphase structure by such as SiC nanowires,thereby improving the interfacial bonding strength between the coatings and between the coatings and the substrate.The focus of composition optimization is to improve the performance of the coatings under high temperature loads by rare earth silicates,etc.The modification strategies of various modified coatings are emphatically introduced,which is helpful to guide the preparation of high-performance C/SiC coating materials in the future.
基金financially supported by the National Natural Science Foundation of China(No.51971251)。
文摘Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis.Herein,porous Ti Fe2intermetallics were fabricated by the reactive synthesis of elemental powders.The phase transformation and pore formation of porous TiFe2intermetallics were investigated,and its corrosion behavior and hydrogen evolution reaction(HER)performance in alkali solution were studied.Porous TiFe2intermetallics with porosity in the range of 34.4%-56.4%were synthesized by the diffusion reaction of Ti and Fe elements,and the pore formation of porous TiFe2intermetallic compound is the result of a combination of the bridging effect and the Kirkendall effect.The porous TiFe2samples exhibit better corrosion resistance compared with porous 316L stainless steel,which is related to the formation of uniform nanosheets on the surface that hinder further corrosion,and porous TiFe2electrode shows the overpotential of 220.6 and 295.6 mV at 10 and 100 mA·cm-2,suggesting a good catalytic performance.The synthesized porous Fe-based intermetallic has a controllable pore structure as well as excellent corrosion resistance,showing its potential in the field of filtration and separation.
基金financially supported by the Fundamental Research Funds for the Central Universities(Grant No.30923011018)。
文摘The present study introduces a screw-pressing charging method to tackle deficiencies in automation and charge uniformity during the melt-casting of polymer-based energetic materials.To ensure the safety of the experiments,this study used inert materials with similar physical properties to partially substitute for the actual energetic components in the preparation of simulant materials.By thoroughly analyzing slurry physical properties,a simulation framework and an extensive performance evaluation method were developed.Such tools guide the design of the structure and configuration of process parameters.Results demonstrate that employing the Pin element significantly enhances radial mixing within the screw,minimizes temperature variations in the slurry,and improves both efficiency and safety in the mixing process.Further,adjustments such as widening the cone angle of the barrel,modifying the solid content of the slurry,and varying the speed of the screw can optimize the mechanical and thermal coupling in the flow field.These adjustments promote higher-quality slurry and create a safer production environment for the extrusion process.
基金Shenzhen Science and Technology Program(KJZD20230923113900001)Project of Industry and Information Technology Bureau of Shenzhen Municipality(201806071403422960)。
文摘The hot compression curves and deformed microstructures were investigated under various hot deformation conditions in three states:hot isostatic pressing(HIP,A1),HIP+hot extrusion at 1100℃(A2),and HIP+hot extrusion at 1150℃(A3).The results show that A2 sample,extruded at 1100℃ with uniform γ+γ′duplex microstructures,demonstrates excellent hot deformation behavior at both 1050 and 1100℃.The true stress-true strain curves of A2 sample maintain a hardening-softening equilibrium over a larger strain range,with post-deformation average grain size of 5μm.The as-HIPed A1 sample and 1150℃ extruded A3 sample exhibit a softening region in deformation curves at 1050℃,and the grain microstructures reflect an incomplete recrystallized state,i.e.combination of fine recrystallized grains and initial larger grains,characterized by a necklace-like microstructure.The predominant recrystallization mechanism for these samples is strain-induced boundary migration.At 1150℃ with a strain rate of 0.001 s^(-1),the influence of the initial microstructure on hot deformation behavior and resultant microstructure is relatively less pronounced,and postdeformation microstructures are fully recrystallized grains.Fine-grained microstructures are conducive to maximizing the hot deformation potential of alloy.By judiciously adjusting deformation regimes,a fine and uniform deformed microstructure can be obtained.
基金Shenzhen Science and Technology Program(JSGG20220831092800001)。
文摘The microstructure of single crystal superalloy is relatively simple,consisting primarily ofγdendrites andγ/γ′eutectics.During the directional solidification process of Ni-based single crystal superalloys,withdrawal rate is a critical parameter affecting the spatial distribution ofγ/γ′eutectic along gravity direction.The results show that theγ/γ′eutectic fraction of the upper platform surface is always higher than that of the lower one,regardless of withdrawal rate.As the withdrawal rate decreases,there is a significant increase inγ/γ′eutectic fraction on the upper surface,while it decreases on the lower surface.The upward accumulation ofγ/γ′eutectic becomes more severe as the withdrawal rate decreases.It is also found that the percentage of Al+Ta is positively correlated with theγ/γ′eutectic fraction.Thermo-solute convection of Al and Ta solutes in the solidification front is the prime reason for the non-uniform distribution of eutectic.The non-uniform distribution ofγ/γ′eutectic cannot be eliminated even after subsequent solution heat treatment,resulting in excess eutectic on the upper surface and thus leading to the scrapping of the blade.
基金Project(2021RC3003) supported by the Hunan Science and Technology Innovation Talents Program,China。
文摘The present investigation introduces a composite frequency selective Rasorber(CFSR)that demonstrates a wide−1 dB transmission band,two high absorption bands with absorptivity higher than 90%,and large oblique incidence angles up to 60°.The CFSR consists of four functional layers separated by three dielectric slabs,which includes lossless metasurface-Ⅰ(MS-Ⅰ),loss metasurface-Ⅱ(MS-Ⅱ),loss metasurface-Ⅲ(MS-Ⅲ),and a three-dimensional metastructure(3D-MS).MS-Ⅰfunctions as a reflector for two absorption bands with a minimal insertion loss transmission window.MS-Ⅱis designed for high-frequency absorption.MS-Ⅲserves as a low-frequency absorption layer for CFSR and an impedance matching layer for MS-Ⅱ.The design methodologies for the transmission window in MS-III and the introduction of 3D-MS are key to achieving high-performance CFSR.The physical mechanisms of CFSR are explained through equivalent circuit model(ECM)analysis and impedance characterization.Finally,measurement results confirm that the proposed CFSR exhibits a−1 dB transmission band ranging from 8.79 to 10.41 GHz with a minimum insertion loss of 0.44 dB at 9.59 GHz;furthermore,the frequency range where reflection coefficient remains below−10 dB is measured to be between 3.33 and 18.00 GHz,aligning well with simulation outcomes.
基金financially supported by the National Natural Science Foundation of China(No.52271014)the Foundation of Education Bureau of Hunan Province(No.22B0163)Jiangxi Provincial Department of Education(No.GJJ2200819)。
文摘The durability performance in molten aluminum with high chemical activity is considered to be a crucial factor for the application of traditional ceramicmatrix composites in the aluminum industry.Herein,novel Ti(C,N)cermet composites with excellent corrosion resistance,featuring distinct ratios of high-entropy alloy binders,were meticulously synthesized by spark plasma sintering(SPS).The synergetic effect of porosity and binder on the corrosion resistance was detailed analyzed.The results show that 8 wt%binder provides an optimum balance of porosity,hardness,fracture toughness and corrosion resistance of the cermets.The appealing corrosion resistance is intimately associated with the formation of a continuous layer consisting of Ti N/Al N,which is introduced through the decarburization of the Ti(C,N)cermets.Additionally,a corrosion mechanism is proposed to elucidate the formation of alternating morphologies within the reaction layers of the cermets.This work is beneficial for selecting structural materials for use in the aluminum industry.
基金Project(52204378)supported by the National Natural Science Foundation of China。
文摘The selective reduction of carbon dioxide(CO_(2))into high-value-added chemicals is one of the most effective means to solve the current energy and environmental problems,which could realize the utilization of CO_(2) and promote the balance of the carbon cycle.Formate is one of the most economical and practical products of all the electrochemical CO_(2) reduction products.Among the many metal-based electrocatalysts that can convert CO_(2) into formate,Sn-based catalysts have received a lot of attention because of their low-cost,non-toxic characteristics and high selectivity for formate.In this article,the most recent development of Sn-based electrocatalysts is comprehensively summarized by giving examples,which are mainly divided into monometallic Sn,alloyed Sn,Sn-based compounds and Sn composite catalysts.Finally,the current performance enhancement strategies and future directions of the field are summarized.
基金supported by the Central South University Innovation-Driven Research Programme(No.2023CXQD009).
文摘Iron disulfide(FeS_(2))has been widely used in thermal batteries because of its high theoretical specific capacity and voltage plateau.However,low thermal decomposition temperature,poor conductivity and inferior actual specific capacity limit its wide applications.Herein,we report a gold-doped FeS_(2)(FeS_(2)-Au),which not only reduces the band gap of the FeS_(2)crystals but also enriches the electron transport path of FeS_(2)by the formation of Au nanoparticles.First-principles calculation shows that the diffusion energy barrier of lithium-ion is reduced after the Au-doped FeS_(2).In addition,Au increases the electron cloud density around sulfur atoms,which helps to enhance the stability of Fe-S covalent bonds and thus results in better thermal stability of FeS_(2).When the Au content is 130μg·g^(-1)(FeS_(2)-Au_(4)),the thermal decomposition temperature(TG5%)of FeS_(2)-Au is 72.2℃ higher than that of pristine FeS_(2).At a discharge temperature of 500℃,a current density of 200 mA·cm^(-2) and a cutoff voltage of 1.4 V,FeS_(2)-Au_(4)demonstrates superior specific capacity and high specific energy compared to FeS_(2).More precisely,the specific capacity of FeS_(2)-Au_(4)attains a value of 379 mAh·g^(-1),with a corresponding specific energy of 714 Wh·kg^(-1).In contrast,the discharge specific capacity and specific energy of FeS_(2)are lower,amounting to 348 mAh·g^(-1)and 656 Wh·kg^(-1),respectively.This study offers a novel approach to enhancing the electrochemical performance of FeS_(2)in high-temperature molten salt electrochemical systems(thermal batteries),thereby laying a solid foundation for its potential practical application.
基金Project(2019yff0216502)supported by the National Key Research&Development Plan of Ministry of Science and Technology of ChinaProject(2021SK1020-4)supported by the Major Science and Technological Innovation Project of Hunan Province,China。
文摘Removing copper from nickel electrolysis anode solution has been a major keypoint in the nickel metallurgy industry.In this study,we proposed a novel process flow to promote removing copper from nickel electrolysis anode solution.A simulated nickel anode solution was designed,and static and dynamic adsorption experiments were conducted to determine the best of solution pH,adsorption time and temperature,resin dosage and particle size,and stirring speed.The optimal conditions were explored for copper removal from nickel electrolysis anode solution.Based on the optimal experimental conditions and the relevant experimental data,a novel process for copper removal from nickel electrolysis anodes was designed and verified.This novel process of copper removal from nickel electrolysis anodes was confirmed with nickel anolyte solution with nickel 50−60 g/L and copper 0.5 g/L.After finishing the novel process of copper removal,the nickel in the purified nickel anolyte became undetectable and copper concentration was 3 mg/L,the novel process of resin adsorption to remove copper from nickel anode solution through static and dynamic adsorptions has an efficacious copper removal.It is a beneficial supplement to traditional methods.
基金the Major Science and Technology Demonstration Projects in Jiangsu Province(Grant No.BE2022608).
文摘Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by adding carboxyl-modified silica(C-SiO2),PAA,and CaCl_(2) to achieve higher viscosity over 25℃.The rheological behavior of C-SiO_(2)-based shear thickening fluid(CS-STF)was investigated at a temperature range of 25–55℃.Unlike SiO_(2)-based STF,which exhibits single-step thickening and a negative correlation between viscosity and temperature.As the C-SiO_(2) content was 41%(w/w)and the mass ratio of PAA:CaCl_(2):C-SiO_(2) was 3:1:10,the CS-STF displayed a double-thickening behavior,and the peak viscosity reached 1330 Pa·s at 35℃.From the yarn pull-out test,the inter-yarn force was significantly increased with the increasing CS-STF content.Treating UHMWPE fabrics with CS-STF improved the impact resistance effectively.In the blunt impact test,the U-CS fabrics with high CS-STF content(121.45 wt%)experienced penetration failure under high impact energy(18 J)due to stress concentration caused by the shear thickening behavior.The knife stabbing test demonstrated that U-CS fabrics with appropriate content(88.38 wt%)have the best stabbing resistance in various impact energies.Overall,this study proposed a high-performence STF showing double-thickening and enhancing shear-thickening behavior at a wide temperature range,the composite fabrics with the performance of resisting both the blunt and stab impact had broad application prospects in the field of personal protection.
基金supported by the National Natural Science Foundation of China(No.52271177)Leading Talents Project of Scientific and Technological Innovation in Hunan Province,China(No.2021RC4036)+1 种基金the Natural Science Foundation of Hunan Province,China(Nos.2023JJ50172,2020JJ6069)State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology,China。
文摘The mechanical properties and oxidation resistance of two nickel-based superalloys with and without oxide dispersion strengthened(ODS)phases at different temperatures were studied.The microstructure was investigated by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).The results show that the yield strength of the samples with and without ODS phases at room temperature is 1020 and 324 MPa,respectively.The yield strength model was constructed,and it is found that the contribution of grain boundary strengthening,dislocation strengthening and nanoparticle strengthening of nickel-based ODS superalloy exceeds 83%.As the temperature increases,grain boundary sliding and migration decrease the strength of sample but improve its ductility.Oxidation hinders the ductility of sample and intensifies its fracture,and the maximum elongation of nickel-based ODS superalloy at 800℃ is 47.3%.
基金supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX23_0120)the National Natural Science Foundation of China(Nos.22275088 and 52101260)+3 种基金the Project of Shuangchuang Scholar of Jiangsu Province(No.JSSCBS20210212)the Fundamental Research Funds for the Central Universities(No.30921011203)the Start-Up Grant(No.AE89991/340)from Nanjing University of Science and Technology,the Foundation of Jiangsu Educational Committee(No.22KJB310008)the Senior Talent Program of Jiangsu University(No.20JDG073).
文摘The reduction of global carbon emissions and the achievement of carbon neutrality have become the focus of addressing climate change and global warming.Electrochemical CO_(2) reduction(CO_(2)RR),as a technology that can efficiently convert CO_(2) into value-added products,is receiving widespread attention.This article reviews the current research status of Cu/metal oxide heterostructures in the field of electrochemical reduction of CO_(2).The review first introduces the importance of electrochemical reduction of CO_(2) and the application potential of Cu/metal oxide heterostructures in this field.Subsequently,a comprehensive discussion is presented on the exploration of various Cu/metal oxide heterostructures and their corresponding structure-performance relationship,with particular emphasis on the catalysts'activity,selectivity,stability and the nature of active sites.Lastly,the review provides an overview of the current research challenges and future development trends in this field.
基金Projects(51274240,51204209) supported by the National Natural Science Foundation of ChinaProject(2012M521545) supported by the National Postdoctoral Science Foundation of China
文摘A process of purification of coal-based coke powder as anode the treatment of coke powder with dilute hydrofluoric acid solution, for Li-ion batteries was attempted. The process started with followed by united-acid-leaching using sulfuric acid and hydrochloric acid. The effects of altering the hydrofluoric acid addition, hydrofluoric acid concentration, contact time, temperature and acid type were investigated. A minimum ash content of 0.35% was obtained when proper conditions were applied. The electrochemical performance of purified coke powder shows greatly improved electrochemical performance. The as-purified coke powder presented an initial reversible capacity of 257.4 mAh/g and a retention rate of 95% after 50 cycles. The proposed purification process paves a way to prepare a promising anode material with good performance with low cost of coke powder for Li-ion batteries.
基金supported financially by the National Key Research and Development Program of China(No.2018YFB0704100)the Outstanding Graduate Project of Advanced Non-ferrous Metal Structural Materials and Manufacturing Collaborative Innovation Center+2 种基金the Funding from the Opening Project of State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilizationthe Project of Innovation and Entrepreneur Team Introduced by Guangdong Province(No.201301G0105337290)the Special Funds for Future Industrial Development of Shenzhen(No.HKHTZD20140702020004)。
文摘In this study,the selective laser melting(SLM)technology has been employed to manufacture a nickelbased superalloy which was conventionally prepared through powder metallurgy(PM)route.The microstructural features and defects were systematically investigated both prior to and after heat treatment and compared with the PM counterpart.Both solidification cracking and liquation cracking were observed in the SLM specimen in which the grain misorientation and low melting point(γ+γ')eutectic played a vital role in their formation mechanism.Columnar grains oriented along building direction were ubiquitous,corresponding to strong<001>fiber texture.Solidification cell structures and melt pools are pervasive and noγ'precipitates were detected at about 10 nm scale before heat treatment.After supersolvus solution and two-step aging treatments,high volume fractionγ'precipitates emerged and their sizes and morphologies were comparable to those in PM alloy.<001>texture is relieved and columnar grains tend to become more equiaxed due to static recrystallization process and grain boundary migration events.Significant annealing twins formed in SLM alloy and are clarified as a consequence of recrystallization.Our results provide fundamental understandings for the SLM PM nickel-based superalloy both before and after heat treatment and demonstrate the potential to fabricate this group of alloys using SLM technology.
文摘Effects of metal (Ni, Cu, Al) and composite metal (NiB, NiCu, NiCuB) nanopowders on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellant ammonium perchlorate/hydroxyterminated polybutadiene (AP/HTPB) were studied by thermal analysis (DTA). The results show that metal and composite metal nanopowders all have good catalytic effects on the thermal decomposition of AP and AP/HTPB composite solid propellant. The effects of metal nanopowders on the thermal decomposition of AP are less than those of the composite metal nanopowders. The effects of metal and composite metal nanopowders on the thermal decomposition of AP are different from those on the thermal decomposition of the AP/HTPB composite solid propellant.
基金Project supported bythe National Natural Science Foundation of China (50306008) and the Fund fromthe Preli minary Research Project of General Equipment Ministry (41328030507)
文摘Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating combustion, the desired nanocrystalline perovskite LaMnO3 was obtained and no further calcination was carried out. The possible processes of combustion reaction were discussed according to the principle of propellant chemistry. The autocombustion and thermal decomposition of the precursor were investigated using the TG-DTA and FT-IR techniques. The influences of glycine-nitrate molar ratio and heat-treatment temperature on the perovskite phase formation and crystallite size of as-burnt powder were studied by XRD. The morphology and size of the as-burnt powder before and after milling were characterized and compared by TEM.
基金Project(2012AA03A514)supported by the National High-Tech Research and Development Program of ChinaProjects(2016YFB0700300,2016YFB0701404)supported by the National Key Research and Development Program of China
文摘The effects of size distribution,morphology and volume fraction ofγ′phase and grain size on tensile properties of powder processed Ni-based superalloy were investigated by using two different quenching methods.Oil quenching and air cooling were adopted with cooling rate of 183°C/s and 4?15°C/s,respectively.The experimental results show that the average size of the secondaryγ′after oil quenching is 24.5 nm compared with 49.8 nm under air cooling,and corresponding volume fractions ofγ′are 29%and 34%,respectively.Meanwhile,the average grain size remains nearly equivalent from both oil-quenching and air-cooling specimens.The tensile strength at room temperature is higher for the oil-quenched specimen than the equivalent from the air-cooled specimen,but the difference approaches each other as the temperature increases to 650°C.The fractography clearly demonstrates that transgranular fracture governs the failure process at ambient temperature,in contrast to the intergranular fracture at 650°C or even higher temperature.These two mechanical responses indicate the strengthening effects ofγ′precipitates and grain boundary for polycrystalline Ni-based superalloys at different temperatures.
基金financially supported by the National Key R&D Program of China(No.2017YFB0305401)the National Natural Science Foundation of China(Nos.51874369 and 51871249)the Huxiang Young Talents Plan(No.2018RS3007)。
文摘With the rapid development of indium tin oxide(ITO)in the electronic display industry,choosing which raw powders to prepare high-quality ITO targets has always been a controversial topic.In the work,in order to clearly understand the effect of the raw powders on the microstructure and properties of ITO targets and thin films,tin-doped indium oxide(dITO)and In_(2)O_3-SnO_(2)mixed(mITO)powders were chosen to prepare ITO targets for depositing the films and a comparative study on their microstructure and properties was conducted.It is found that,(1)dITO targets possess a higher solid solubility of tin in indium oxide and more uniform elemental distribution,while there are a higher density,a finer grain size and a higher mass ratio of In_(2)O_3 to SnO_(2)for the mITO targets;(2)dITO films with more coarser columnar grains and a rougher surface prefer to grow along the[100]direction in an Ar atmosphere;(3)the conductive property of ITO films only depends on the doping amount of tin and is independent of the raw powders and the preparation process of the target source;(4)dITO films possess the superior optical property and narrower optical band gap;(5)the etching property of mITO films is superior to that of dITO films due to the lower solid solubility of tin in indium oxide.
