Wedge-shaped copper casting experiment was conducted to study the engulfment behavior of TiB2 particle and the interaction between particle or cluster and the solid/liquid front in commercial pure aluminum matrix. The...Wedge-shaped copper casting experiment was conducted to study the engulfment behavior of TiB2 particle and the interaction between particle or cluster and the solid/liquid front in commercial pure aluminum matrix. The experimental results show that the particle size distribution obeys two separate systems in the whole wedge-cast sample. Furthermore, it is found that the big clusters are pushed to the center of the wedge shaped sample and the single particle or small clusters consisting of few particles are engulfed into the α-Al in the area of the sample edge. The cluster degree of particles varies in different areas, and its value is 0.2 and 0.6 for the cluster fraction in the edge and in the center of the wedge sample, respectively. The cluster diameter does not obey the normal distribution but approximately obeys lognormal distribution in the present work. More importantly, in the whole sample, the particle size obeys two separate log-normal distributions.展开更多
Bulk Cu-Ti alloy reinforced by TiB2 nano particles was prepared using in-situ reaction between Cu 3.4%Ti and Cu-0.7%B master alloys along with rapid solidification and subsequent heat treatment for 1-10 h at 900 ℃. H...Bulk Cu-Ti alloy reinforced by TiB2 nano particles was prepared using in-situ reaction between Cu 3.4%Ti and Cu-0.7%B master alloys along with rapid solidification and subsequent heat treatment for 1-10 h at 900 ℃. High-resolution transmission electron microscopy （HRTEM） characterization showed that primary TiB2 nano particles and TiB whiskers were formed by in-situ reaction between Ti and B in the liquid copper. The formation of TiB whiskers within the melt led to coarsening of TiB2 particles. Primary TiB2 particles were dispersed along the grain boundaries and hindered grain growth at high temperature, while the secondary TiB2 particles were formed during heat treatment of the alloy by diffusion reaction of solute titanium and boron inside the grains. Electrical conductivity and hardness of the composite were evaluated during heat treatment. The results indicated that the formation of secondary TiB2 particles in the matrix caused a delay in hardness reduction at high temperature. The electrical conductivity and hardness increased up to 8 h of heat treatment and reached 33.5% IACS and HV 158, respectively.展开更多
A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDO...A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMC particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more homogeneously.Besides,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress mitigation.This paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMC active particles mitigates stress levels.展开更多
Molecular dynamics(MD)simulations are employed to delve into the multifaceted effects of TiB2 nanoparticles on the intricate grain refinement mechanism,microstructural evolution,and tensile performance of Inconel 718 ...Molecular dynamics(MD)simulations are employed to delve into the multifaceted effects of TiB2 nanoparticles on the intricate grain refinement mechanism,microstructural evolution,and tensile performance of Inconel 718 superalloys during the rapid directional solidification.Specifically,the study focuses on elucidating the role of TiB2 nanoparticles in augmenting the nucleation rate during the rapid directional solidification process of Ni60Cr21Fe19 alloy system.Furthermore,subsequent tensile simulations are conducted to comprehensively evaluate the anisotropic behavior of tensile properties within the solidified microstructures.The MD results reveal that the incorporation of TiB₂nanoparticles during the rapid directional solidification of the Ni_(60)Cr_(21)Fe_(19)significantly enhances the average nucleation rate,escalating it from 1.27×10^(34)m^(-3)·s^(-1)to 2.55×10^(34)m^(-3)·s^(-1).Notably,within the face centered cube(FCC)structure,Ni atoms exhibit pronounced compositional segregation,and the solidified alloy maintains an exceptionally high dislocation density reaching up to 10^(16)m^(-2).Crucially,the rapid directional solidification process imparts a distinct microstructural anisotropy,leading to a notable disparity in tensile strength.Specifically,the tensile strength along the solidification direction is markedly superior to that perpendicular to it.This disparity arises from different deformation mechanisms under varying loading orientations.Tensile stress perpendicular to the solidification direction encourages the formation of smooth and organized mechanical twins.These twins act as slip planes,enhancing dislocation mobility and thereby improving stress relaxation and dispersion.Moreover,the results underscore the profound strengthening effect of TiB2 nanoparticles,particularly in enhancing the tensile strength along the rapid directional solidification direction.展开更多
We derive an effective Hamiltonian for a spin-1/2 particle confined within a curved thin layer with non-uniform thickness using the confining potential approach.Our analysis reveals the presence of a pseudo-magnetic f...We derive an effective Hamiltonian for a spin-1/2 particle confined within a curved thin layer with non-uniform thickness using the confining potential approach.Our analysis reveals the presence of a pseudo-magnetic field and effective spin–orbit interaction(SOI)arising from the curvature,as well as an effective scalar potential resulting from variations in thickness.Importantly,we demonstrate that the physical effect of additional SOI from thickness fluctuations vanishes in low-dimensional systems,thus guaranteeing the robustness of spin interference measurements to thickness imperfection.Furthermore,we establish the applicability of the effective Hamiltonian in both symmetric and asymmetric confinement scenarios,which is crucial for its utilization in one-side etching systems.展开更多
The capture,regeneration,and conversion of CO_(2) from ambient air and flue gas streams are critical aspects of mitigating global warming.Solid sorbents for CO_(2) absorption are very promising as they have high mass ...The capture,regeneration,and conversion of CO_(2) from ambient air and flue gas streams are critical aspects of mitigating global warming.Solid sorbents for CO_(2) absorption are very promising as they have high mass transfer areas without energy input and reduce emissions and minimize corrosion as compared to liquid sorbents.However,precisely tunable solid CO_(2) sorbents are difficult to produce.Here,we demonstrate the high-throughput production of hydrogel-based CO_(2)-absorbing particles via liquid jetting.By wrapping a liquid jet consisting of an aqueous solution of cross-linkable branched polyethylenimine(PEI)with a layer of suspension containing hydrophobic silica nanoparticles,monodisperse droplets with a silica nanoparticle coating layer was formed in the air.A stable Pickering emulsion containing PEI droplets was obtained after these ejected droplets were collected in a heated oil bath.The droplets turn into mm-sized particles after thermal curing in the bath.The diameter,PEI content,and silica content of the particles were systematically varied,and their CO_(2) absorption was measured as a function of time.Steam regeneration of the particles enabled cyclic testing,revealing a CO_(2) absorption capacity of 6.5±0.5 mol kg^(−1)solid PEI in pure CO_(2) environments and 0.7±0.3 mol kg^(−1)solid PEI for direct air capture.Several thousands of particles were produced per second at a rate of around 0.5 kg per hour,with a single nozzle.This process can be further scaled by parallelization.The complete toolbox for the design,fabrication,testing,and regeneration of functional hydrogel particles provides a powerful route toward novel solid sorbents for regenerative CO_(2) capture.展开更多
This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weather...This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weathering on limestone using the freezing and thawing(F-T)for 40 cycles.The mechanical parameters of the samples were measured at the end of the 40th cycle.In the second configuration,a series of specimens underwent salt crystallization(S-C)tests for 20 cycles.Experimental results were validated using discrete element method(DEM).Next,the weathered limestone model with dimensions of 108 mm54 mm were prepared.The weathering layers were tested at four different thicknesses(i.e.2.5 mm,5 mm,7.5 mm,and 10 mm)and three different positions(at the surface,5 mm under the rock surface,and 10 mm under the rock surface).According to the results,weathering depth and thickness have a considerable effect on the failure process.The results also showed a correlation between the values of compressive strength and failure mechanisms associated with the weathering layer.The numerical results revealed that the tension crack was the dominant factor.Additionally,with increasing weathering thickness,Young's modulus,crack initiation stress,and final strength decreased in constant weathering depth.The results also demonstrated that the failure progress of the numerical models was similar to that observed in the laboratory.展开更多
Simulations are conducted on capacitively coupled Ar/O_(2)mixed gas discharges employing a one-dimensional fluid coupled with an electron Monte Carlo(MC)model.The research explores the impact of different O_(2)ratio a...Simulations are conducted on capacitively coupled Ar/O_(2)mixed gas discharges employing a one-dimensional fluid coupled with an electron Monte Carlo(MC)model.The research explores the impact of different O_(2)ratio and pressures on the discharge characteristics of Ar/O_(2)plasma.At a fixed Ar/O_(2)gas ratio,with the increasing pressure,higher ion densities,as well as a slight increase in electron density in the bulk region can be observed.The discharge remains dominated by the drift-ambipolar(DA)mode,and the flux of O(3P)at the electrode increases with the increasing pressure due to higher background gas density,while the fluxes of O(1D)and Ardecrease due to the pronounced loss rate.With the increasing proportion of O_(2),a change in the dominant discharge mode from a mode to DA mode can be detected,and the O_(2)-associated charged particle densities are significantly increased.However,Ar+density shows a trend of increasing and then decreasing,while for neutral fluxes at the electrode,Arflux decreases,and O(3P)flux increases with the reduced Ar gas proportion,while trends in O(1D)flux show slight differences.The evolution of the densities of the charged particle and the neutral fluxes under different discharge parameters are discussed in detail using the ionization characteristics as well as the transport properties.Hopefully,more comprehensive understanding of Ar/O_(2)discharge characteristics in this work will provide a valuable reference for the industry.展开更多
In-situ TiB_2/AZ31 composites were prepared by utilizing the SHS reaction of Al-Ti-B system in the molten magnesium,and the effects of external physical fields on the dispersion of TiB_2 particles were investigated.Th...In-situ TiB_2/AZ31 composites were prepared by utilizing the SHS reaction of Al-Ti-B system in the molten magnesium,and the effects of external physical fields on the dispersion of TiB_2 particles were investigated.The results show that high-energy ultrasonic vibration could effectively break up the particle clusters and make the TiB2 particles uniformly distributed in the melt of TiB_2/AZ31 composites.The compound field(high-energy ultrasonic field coupling with electromagnetic field)could not only distribute the TiB_2 particles into the matrix uniformly,but also make the grains of α-Mg free and uniform further than the ultrasonic field solo.The average grain size of as-cast TiB_2/AZ31 composites was reduced from 173μm to 94μm.展开更多
文摘Wedge-shaped copper casting experiment was conducted to study the engulfment behavior of TiB2 particle and the interaction between particle or cluster and the solid/liquid front in commercial pure aluminum matrix. The experimental results show that the particle size distribution obeys two separate systems in the whole wedge-cast sample. Furthermore, it is found that the big clusters are pushed to the center of the wedge shaped sample and the single particle or small clusters consisting of few particles are engulfed into the α-Al in the area of the sample edge. The cluster degree of particles varies in different areas, and its value is 0.2 and 0.6 for the cluster fraction in the edge and in the center of the wedge sample, respectively. The cluster diameter does not obey the normal distribution but approximately obeys lognormal distribution in the present work. More importantly, in the whole sample, the particle size obeys two separate log-normal distributions.
基金the Iranian nanotechnology initiative for financially supporting this project
文摘Bulk Cu-Ti alloy reinforced by TiB2 nano particles was prepared using in-situ reaction between Cu 3.4%Ti and Cu-0.7%B master alloys along with rapid solidification and subsequent heat treatment for 1-10 h at 900 ℃. High-resolution transmission electron microscopy （HRTEM） characterization showed that primary TiB2 nano particles and TiB whiskers were formed by in-situ reaction between Ti and B in the liquid copper. The formation of TiB whiskers within the melt led to coarsening of TiB2 particles. Primary TiB2 particles were dispersed along the grain boundaries and hindered grain growth at high temperature, while the secondary TiB2 particles were formed during heat treatment of the alloy by diffusion reaction of solute titanium and boron inside the grains. Electrical conductivity and hardness of the composite were evaluated during heat treatment. The results indicated that the formation of secondary TiB2 particles in the matrix caused a delay in hardness reduction at high temperature. The electrical conductivity and hardness increased up to 8 h of heat treatment and reached 33.5% IACS and HV 158, respectively.
基金the National Research Foundation of Korea(Nos.2018R1A5A7023490 and 2022R1A2C1003003)。
文摘A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMC particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more homogeneously.Besides,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress mitigation.This paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMC active particles mitigates stress levels.
基金supported by the Na⁃tional Natural Science Foundation of China(Nos.12462006,12062016)the high-performance computing services of⁃fered by the Information Center of Nanchang Hangkong Uni⁃versity.
文摘Molecular dynamics(MD)simulations are employed to delve into the multifaceted effects of TiB2 nanoparticles on the intricate grain refinement mechanism,microstructural evolution,and tensile performance of Inconel 718 superalloys during the rapid directional solidification.Specifically,the study focuses on elucidating the role of TiB2 nanoparticles in augmenting the nucleation rate during the rapid directional solidification process of Ni60Cr21Fe19 alloy system.Furthermore,subsequent tensile simulations are conducted to comprehensively evaluate the anisotropic behavior of tensile properties within the solidified microstructures.The MD results reveal that the incorporation of TiB₂nanoparticles during the rapid directional solidification of the Ni_(60)Cr_(21)Fe_(19)significantly enhances the average nucleation rate,escalating it from 1.27×10^(34)m^(-3)·s^(-1)to 2.55×10^(34)m^(-3)·s^(-1).Notably,within the face centered cube(FCC)structure,Ni atoms exhibit pronounced compositional segregation,and the solidified alloy maintains an exceptionally high dislocation density reaching up to 10^(16)m^(-2).Crucially,the rapid directional solidification process imparts a distinct microstructural anisotropy,leading to a notable disparity in tensile strength.Specifically,the tensile strength along the solidification direction is markedly superior to that perpendicular to it.This disparity arises from different deformation mechanisms under varying loading orientations.Tensile stress perpendicular to the solidification direction encourages the formation of smooth and organized mechanical twins.These twins act as slip planes,enhancing dislocation mobility and thereby improving stress relaxation and dispersion.Moreover,the results underscore the profound strengthening effect of TiB2 nanoparticles,particularly in enhancing the tensile strength along the rapid directional solidification direction.
基金This work was supported in part by the National Natural Science Foundation of China(Grant No.12104239)National Natural Science Foundation of Jiangsu Province of China(Grant No.BK20210581)+2 种基金Nanjing University of Posts and Telecommunications Science Foundation(Grant Nos.NY221024 and NY221100)the Science and Technology Program of Guangxi,China(Grant No.2018AD19310)the Jiangxi Provincial Natural Science Foundation(Grant No.20224BAB211020).
文摘We derive an effective Hamiltonian for a spin-1/2 particle confined within a curved thin layer with non-uniform thickness using the confining potential approach.Our analysis reveals the presence of a pseudo-magnetic field and effective spin–orbit interaction(SOI)arising from the curvature,as well as an effective scalar potential resulting from variations in thickness.Importantly,we demonstrate that the physical effect of additional SOI from thickness fluctuations vanishes in low-dimensional systems,thus guaranteeing the robustness of spin interference measurements to thickness imperfection.Furthermore,we establish the applicability of the effective Hamiltonian in both symmetric and asymmetric confinement scenarios,which is crucial for its utilization in one-side etching systems.
基金supported by the European Regional Development Fund(CONTROL,EFRO#00943).
文摘The capture,regeneration,and conversion of CO_(2) from ambient air and flue gas streams are critical aspects of mitigating global warming.Solid sorbents for CO_(2) absorption are very promising as they have high mass transfer areas without energy input and reduce emissions and minimize corrosion as compared to liquid sorbents.However,precisely tunable solid CO_(2) sorbents are difficult to produce.Here,we demonstrate the high-throughput production of hydrogel-based CO_(2)-absorbing particles via liquid jetting.By wrapping a liquid jet consisting of an aqueous solution of cross-linkable branched polyethylenimine(PEI)with a layer of suspension containing hydrophobic silica nanoparticles,monodisperse droplets with a silica nanoparticle coating layer was formed in the air.A stable Pickering emulsion containing PEI droplets was obtained after these ejected droplets were collected in a heated oil bath.The droplets turn into mm-sized particles after thermal curing in the bath.The diameter,PEI content,and silica content of the particles were systematically varied,and their CO_(2) absorption was measured as a function of time.Steam regeneration of the particles enabled cyclic testing,revealing a CO_(2) absorption capacity of 6.5±0.5 mol kg^(−1)solid PEI in pure CO_(2) environments and 0.7±0.3 mol kg^(−1)solid PEI for direct air capture.Several thousands of particles were produced per second at a rate of around 0.5 kg per hour,with a single nozzle.This process can be further scaled by parallelization.The complete toolbox for the design,fabrication,testing,and regeneration of functional hydrogel particles provides a powerful route toward novel solid sorbents for regenerative CO_(2) capture.
文摘This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weathering on limestone using the freezing and thawing(F-T)for 40 cycles.The mechanical parameters of the samples were measured at the end of the 40th cycle.In the second configuration,a series of specimens underwent salt crystallization(S-C)tests for 20 cycles.Experimental results were validated using discrete element method(DEM).Next,the weathered limestone model with dimensions of 108 mm54 mm were prepared.The weathering layers were tested at four different thicknesses(i.e.2.5 mm,5 mm,7.5 mm,and 10 mm)and three different positions(at the surface,5 mm under the rock surface,and 10 mm under the rock surface).According to the results,weathering depth and thickness have a considerable effect on the failure process.The results also showed a correlation between the values of compressive strength and failure mechanisms associated with the weathering layer.The numerical results revealed that the tension crack was the dominant factor.Additionally,with increasing weathering thickness,Young's modulus,crack initiation stress,and final strength decreased in constant weathering depth.The results also demonstrated that the failure progress of the numerical models was similar to that observed in the laboratory.
基金the National Natural Science Foun-dation of China(Grant Nos.12020101005,11975067,and 12347131)the Fundamental Research Funds for the Cen-tral Universities(Grant No.DUT24BS069).
文摘Simulations are conducted on capacitively coupled Ar/O_(2)mixed gas discharges employing a one-dimensional fluid coupled with an electron Monte Carlo(MC)model.The research explores the impact of different O_(2)ratio and pressures on the discharge characteristics of Ar/O_(2)plasma.At a fixed Ar/O_(2)gas ratio,with the increasing pressure,higher ion densities,as well as a slight increase in electron density in the bulk region can be observed.The discharge remains dominated by the drift-ambipolar(DA)mode,and the flux of O(3P)at the electrode increases with the increasing pressure due to higher background gas density,while the fluxes of O(1D)and Ardecrease due to the pronounced loss rate.With the increasing proportion of O_(2),a change in the dominant discharge mode from a mode to DA mode can be detected,and the O_(2)-associated charged particle densities are significantly increased.However,Ar+density shows a trend of increasing and then decreasing,while for neutral fluxes at the electrode,Arflux decreases,and O(3P)flux increases with the reduced Ar gas proportion,while trends in O(1D)flux show slight differences.The evolution of the densities of the charged particle and the neutral fluxes under different discharge parameters are discussed in detail using the ionization characteristics as well as the transport properties.Hopefully,more comprehensive understanding of Ar/O_(2)discharge characteristics in this work will provide a valuable reference for the industry.
基金Item Sponsored by National High Technology Research and Development Program of China[No.2009AA03Z525]Aviation Science Foundation of China[No.20095263005]
文摘In-situ TiB_2/AZ31 composites were prepared by utilizing the SHS reaction of Al-Ti-B system in the molten magnesium,and the effects of external physical fields on the dispersion of TiB_2 particles were investigated.The results show that high-energy ultrasonic vibration could effectively break up the particle clusters and make the TiB2 particles uniformly distributed in the melt of TiB_2/AZ31 composites.The compound field(high-energy ultrasonic field coupling with electromagnetic field)could not only distribute the TiB_2 particles into the matrix uniformly,but also make the grains of α-Mg free and uniform further than the ultrasonic field solo.The average grain size of as-cast TiB_2/AZ31 composites was reduced from 173μm to 94μm.
