Sodium-ion batteries(SIBs)have emerged as a promising alternative to commercial lithium-ion batteries be-cause of the similar properties of Li and Na as well as the abundance and accessibility of sodium resources.The ...Sodium-ion batteries(SIBs)have emerged as a promising alternative to commercial lithium-ion batteries be-cause of the similar properties of Li and Na as well as the abundance and accessibility of sodium resources.The devel-opment of anode materials with a high capacity,excellent rate performance,and long cycle life is the key to the indus-trialization of SIBs.Biomass-derived carbon(BDC)anode materials synthesized from resource-rich,low-cost,and re-newable biomass have been extensively researched and their excellent sodium storage performance has been proven,making them the most promising new low-cost and high-performance anode material for SIBs.This review first intro-duces the sources of BDCs,including waste biomass such as plants,animals,and microorganisms,and then describes sev-eral methods for preparing BDC anode materials,including carbonization,chemical activation,and template methods.The storage mechanism and kinetic process of Na^(+)in BDCs are then considered as well as their structure control.The electrochemical properties of sodium-ion storage in BDCs with different structures are examined,and suggestions for future re-search are made.展开更多
Pitch is a complex mixture of polycyclic aromatic hydrocarbons and their non-metal derivatives that has a high carbon content.Using pitch as a precursor for carbon materials in alkali metal ion(Li^(+)/Na^(+)/K^(+))bat...Pitch is a complex mixture of polycyclic aromatic hydrocarbons and their non-metal derivatives that has a high carbon content.Using pitch as a precursor for carbon materials in alkali metal ion(Li^(+)/Na^(+)/K^(+))batteries has become of great interest.However,its direct pyrolysis often leads to microstructures with a high orientation and small interlayer spacing due to uncontrolled liquid-phase carbonization,resulting in subpar electrochemical performance.It is therefore important to control the microstructures of pitch-derived carbon materials in order to improve their electrochemical properties.We evaluate the latest progress in the development of these materials using various microstructural engineering approaches,highlighting their use in metal-ion batteries and supercapacitors.The advantages and limitations of pitch molecules and their carbon derivatives are outlined,together with strategies for their modification in order to improve their properties for specific applications.Future research possibilities for structure optimization,scalable production,and waste pitch recycling are also considered.展开更多
Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the...Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the reinforcement reliable,this experiment mixed(ultrafine cement)UFC into ordinary cement to form a composite solidify agent.This study aimed to analyze the influence of UFC proportion on the strength of cement-soil in the peat soil environment.Unconfined compressive strength(UCS)and scanning electron microscope(SEM)tests were conducted on samples soaked for 28 and 90 days,respectively.The test results show that without considering the effects of Humic Acid(HA)and Fulvic Acid(FA),incorporating UFC can significantly improve the UCS of cement-soil.The rapid hydration of the fine particles generates a large number of cementitious products,improves the cohesion of the soil skeleton,and fills the pores.However,when the proportion of UFC increases,the aggregate structure formed by a larger quantity of fine particles reduces the hydration rate and degree of cement hydration,making the UCS growth rate of cement-soil insignificant.In the peat soil environment,HA significantly weakened the UCS of cement-soil in both physical and chemical aspects.However,UFC can mitigate the adverse effect of HA on cement-soil by its small particle size,high surface energy,and solid binding ability.In addition,FA has a positive effect on the UCS of cement-soil soaked for 28 days and 90 days.The UFC addition could promote the enhancement effect of FA on cement-soil UCS.SEM test results showed that cement hydration products increased significantly with the increase of UFC proportion,and cementation between hydration products and soil particles was enhanced.The size and connectivity of cement-soil pores were significantly reduced,thereby improving cement-soil structural integrity.展开更多
ZnO thin films with varying Ta concentrations were fabricated through magnetron sputtering.The crystallinity and surface morphology of the ZnO films are significantly influenced by the incorporation of Ta,as evidenced...ZnO thin films with varying Ta concentrations were fabricated through magnetron sputtering.The crystallinity and surface morphology of the ZnO films are significantly influenced by the incorporation of Ta,as evidenced by the X-ray diffraction and scanning electron microscopy results.The lattice constants,as determined by X-ray diffraction,contradict the disparity in Ta and Zn ion radii,which is attributed to the impact of interstitial defects.This inconsistency introduces variations in carrier concentration in this experiment compared with prior studies.Subsequent exploration of the luminescent characteristics and emission mechanism of defect levels in Ta-doped ZnO films was conducted through photoluminescence.Furthermore,the factors influencing the bandgap are discussed.展开更多
A relatively well-preserved rodent fossil,including its incisors,cheek teeth,and postcranial skeleton,was collected from the Baiyin Obo in Siziwang Banner,Nei Mongol.A multifaceted research approach was undertaken in ...A relatively well-preserved rodent fossil,including its incisors,cheek teeth,and postcranial skeleton,was collected from the Baiyin Obo in Siziwang Banner,Nei Mongol.A multifaceted research approach was undertaken in this study to conduct a comprehensive analysis on the newly discovered specimen.Based on a morphological comparison,the new specimen was identified as Hulgana cf.H.ertnia within the Ischyromyidae family.Incisive enamel microstructure analysis revealed the typical pauciserial enamel structure of Hulgana.Bone histological analysis indicates that the specimen represents a juvenile individual,which is consistent with the ontogenetic stage indicated by dental developmental stage and wear pattern.The application of geometric morphometrics to the calcaneus and bone histology of the femur and phalanx further substantiates the taxonomic classification of Hulgana as a terrestrial and cursorial rodent,exhibiting a degree of fossorial ability.This classification is analogous to that of certain extant cricetids and ground squirrels.展开更多
Ferrite-rich calcium sulfoaluminate(FCSA)cement is often used in special projects such as marine engineering due to its excellent resistance of seawater attack although the cost is a little high.Ground granulated blas...Ferrite-rich calcium sulfoaluminate(FCSA)cement is often used in special projects such as marine engineering due to its excellent resistance of seawater attack although the cost is a little high.Ground granulated blast furnace slag(GGBS),a byproduct of industrial production,is used as a mineral admixture to reduce concrete costs and provide excellent performance.This study aimed to investigate the impact of GGBS on the hydration properties of FCSA cement in seawater.Tests were conducted on heat of hydration,compressive strength,mass change,and pH value of pore solution of FCSA cement paste with a water-to-binder ratio of 0.45.X-ray diffraction(XRD)analysis and thermogravimetric analysis were used to determine the hydration products,while mercury intrusion porosimetry(MIP)was used to measure pore structure.The results indicated that the FCSA cement hydration showed a concentrated heat release at early age.The compressive strength of specimens consistently increased over time,where seawater curing enhanced the compressive strength of control samples.The pH value of pore solution decreased to 10.7−10.9 at 90 d when cured in seawater.The primary hydration products of FCSA cement included ettringite,iron hydroxide gel(FH_(3)),and aluminum hydroxide gel(AH_(3)).Moreover,when cured in seawater,Friedel’s salt was formed,which enhanced the compressive strength of the specimen and increased its coefficient of corrosion.Seawater curing gradually increased sample mass,and GGBS refined pore structure while reducing harmful pore proportions.These results suggest that while GGBS can refine pore structure and improve certain aspects of performance,its inclusion may also reduce compressive strength,highlighting the need for a balanced approach in its use for marine applications.展开更多
To investigate the effects of water and cyclic loading on dolomite’s mechanical properties during deep mining,mechanical experiments on non-pressure water absorption and cyclic loading were conducted.The findings rev...To investigate the effects of water and cyclic loading on dolomite’s mechanical properties during deep mining,mechanical experiments on non-pressure water absorption and cyclic loading were conducted.The findings reveal that the elastic modulus and Poisson ratio of dolomite fluctuate with increasing water content.The mass of water absorption is positively correlated with time and the water absorption stage can be divided into three stages:accelerated,decelerated,and stabilized stages.During this process,the number of pores in dolomite increases,while the pore diameter initially decreases and then fluctuates.Microscopic analysis shows that the proportion of mesopores first increases and then decreases,while micropores exhibit the opposite trend,and the proportion of macropores fluctuates around 0%.A model diagram of structural evolution during water absorption has been developed.Additionally,the softening process of dolomite’s water absorption strength is categorized into three stages:a relatively stable stage,an accelerated softening stage dominated by mesopore water absorption,and a decelerated softening stage characterized by micropore water absorption.A uniaxial damage constitutive model for dolomite under water influence was established based on the Weibull distribution and Mohr-Coulomb strength criterion,and experimental validation indicates its strong applicability.展开更多
To weaken the basal texture and in-plane anisotropy of magnesium alloy, non-basal slips are pre-enhanced by pre-rolling with a single pass larger strain reduction at elevated temperatures. Then Mg alloy sheets with th...To weaken the basal texture and in-plane anisotropy of magnesium alloy, non-basal slips are pre-enhanced by pre-rolling with a single pass larger strain reduction at elevated temperatures. Then Mg alloy sheets with the thickness of 1 mm are achieved after five passes rolling at 300 ℃. A double peak and disperse basal texture is generated after pre- rolling at higher temperatures when the non-basal slips are more active. So, the texture intensity of pre-rolled samples is reduced. Moreover, the distribution condition of in-grain misorientation axes (a method to analyze the activation of slips) shows that the pyramidal slip is quite active during deformation. After annealing on final rolled sheets, the texture distributions are changed and the intensity of texture reduces obviously due to static recrystallization. In particular, the r-value and in-plane anisotropy of pre-rolled samples are obviously lower than those of sample without pre-rolling.展开更多
In the process of protecting ferrous materials,aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy.However,the capacity of the sacrificial anode is rather insufficient.In order to ...In the process of protecting ferrous materials,aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy.However,the capacity of the sacrificial anode is rather insufficient.In order to solve this problem,the microstructure and electrochemical corrosion properties of Al-8Si-3Fe-xIn alloy under low chlorine conditions were studied.The results show that indium(In)dissolves to form In^(3+)and In^(+)reverse plating on the surface of the bare substrate to form a passivation film defect.When the In content is high,the segregated In forms an activation point in the form of a cathode phase.In activatesτ_(6)phase to form a micro-couple,which improves the non-uniform corrosion.The In-containing corrosion products at the phase boundary hinder the diffusion of Cl−.With an increase of In content,the self-corrosion potential(Ecorr)of the alloy shifts negatively,and the self-corrosion current density(Jcorr)decreases from 6.477μA/cm^(2)to 1.352μA/cm^(2),and then increases gradually.However,when the In content is 0.1%,the Ecorr of the alloy changes from−0.824 V to−0.932 V,and the Jcorr decreases from 6.477μA/cm^(2)to 4.699μA/cm^(2),suggesting that the use of sacrificial anode will give the best effect.展开更多
The research demonstrated that laser powder bed fusion(LPBF)coupled with controlled annealing at 1200°C,could significantly increase the proportion of coincidence site lattice(CSL)grain boundary,thereby achieving...The research demonstrated that laser powder bed fusion(LPBF)coupled with controlled annealing at 1200°C,could significantly increase the proportion of coincidence site lattice(CSL)grain boundary,thereby achieving an outstanding synergy of enhanced strength and exceptional ductility.The plastic deformation behavior,strain hardening behavior,and fracture behavior of LPBF 316L steel annealing at 1200℃for 20 h were studied through quasi-in-situ tensile process.It was found that LPBF 316L steel formed a certain proportion of deformation twins during the tensile process,and the formation of twins changed the crystal orientation,thus promoting further slip and crystal deformation.The synergistic effect of slip and twin promoted higher plasticity.LPBF process coupled with controlled annealing at 1200°C for 20 h leads to a ultimate tensile strength of 613 MPa and total elongation of 73.8%.展开更多
Polyether ether ketone(PEEK)has good mechanical properties.However,its high viscosity when molten limits its use because it is hard to process.PEEK nanocomposites containing both carbon nanotubes(CNTs)and polyether im...Polyether ether ketone(PEEK)has good mechanical properties.However,its high viscosity when molten limits its use because it is hard to process.PEEK nanocomposites containing both carbon nanotubes(CNTs)and polyether imide(PEI)were pre-pared by a direct wet powder blending method using a vertical injection molding machine.The addition of an optimum amount of PEI lowered the viscosity of the molten PEEK by approximately 50%while producing an increase in the toughness of the nanocom-posites,whose strain to failure increased by 129%,and fracture energy increased by 97%.The uniformly dispersed CNT/PEI powder reduced the processing difficulty of PEEK nanocomposites without affecting the thermal resistance.This improvement of the strength and viscosity of PEEK facilitate its use in the preparation of thermoplastic composites.展开更多
In the present study,microstructural evolution,mechanical and creep properties of Al/SiC/Cu composite stripsfabricated via accumulative roll bonding(ARB)process were studied.The obtained results showed the formation o...In the present study,microstructural evolution,mechanical and creep properties of Al/SiC/Cu composite stripsfabricated via accumulative roll bonding(ARB)process were studied.The obtained results showed the formation of anatomic diffusion layer with thickness of about 17μm at the interface during the ARB under three creep loadingconditions namely 30 MPa at 225℃,35 MPa at 225℃,and 35 MPa at 275℃.An generated intermetallic compoundresulted in a 40%increase of interface thickness near Al.The stress level decreased by 13%at constant temperature withno signi fi cant effect on the interface thickness,and the creep failure time declined by 44%.It was observed that atconstant temperatures,the second slope of the creep curve reached to 39%with increasing stress level,then,it dropped to2%with a little temperature rising.After creep test under 35 MPa at 275℃,the sample displays the presence of 60%Aland 40%Cu,containing brittle Al_(2)Cu intermetallic compound at the interface.Applied temperature and stress had effecton the creep properties,specially increasing the slope of creep curves with higher stresses.展开更多
To develop suitable grouting materials for water conveyance tunnels in cold regions,firstly,this study investigated the performance evolution of ferrite-rich sulfoaluminate-based composite cement(FSAC grouting materia...To develop suitable grouting materials for water conveyance tunnels in cold regions,firstly,this study investigated the performance evolution of ferrite-rich sulfoaluminate-based composite cement(FSAC grouting material)at 20 and 3℃.The results show that low temperature only delays the strength development of FSAC grouting material within the first 3 d.Then,the effect of four typical early strength synergists on the early properties of FSAC grouting material was evaluated to optimize the early(£1 d)strength at 3℃.The most effective synergist,Ca(HCOO)_(2),which enhances the low-temperature early strength without compromising fluidity was selected based on strength and fluidity tests.Its micro-mechanism was analyzed by XRD,TG,and SEM methods.The results reveal that the most suitable dosage range is 0.3 wt%−0.5 wt%.Proper addition of Ca(HCOO)_(2)changed the crystal morphology of the hydration products,decreased the pore size and formed more compact hydration products by interlocking and overlapping.However,excessive addition of Ca(HCOO)_(2)inhibited the hydration reaction,resulting in a simple and loose structure of the hydration products.The research results have reference value for controlling surrounding rock deformation and preventing water and mud inrushes during the excavation in cold region tunnels.展开更多
One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm ...One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm for bonding time of 20,40,60,and 90 min.The bonding temperature of 860℃ was considered,which is under the β transus temperature of Cp-Ti.During TLP bonding,various intermetallic compounds(IMCs),including Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe),Ti_(2)(Cu,Ag),and Ti_(2)Cu from 304L toward Cp-Ti formed in the joint.Also,on the one side,with the increase in time,further diffusion of elements decreases the blocky IMCs such as Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe)in the 304L diffusion-affected zone(DAZ)and reaction zone,and on the other side,Ti_(2)(Cu,Ag)IMC transformed into fine morphology toward Cp-Ti DAZ.The microhardness test also demonstrated that the(Cr,Fe)_(2)Ti+Ti_(5)Cr_(7)Fe_(17) IMCs in the DAZ on the side of 304L have a hardness value of HV 564,making it the hardest phase.The maximum and minimum shear strength values are equal to 78.84 and 29.0 MPa,respectively.The cleavage pattern dominated fracture surfaces due to the formation of brittle phases in dissimilar joints.展开更多
(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the...(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the co-precipitation method.Using the synthesized nano-powders as initial material,Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics were fabri-cated by vacuum pre-sintering at different temperatures for 2 h and hot isostatic pressing(HIP)at 1750℃for 3 h in ar-gon.The influence of pre-sintering temperature on the microstructure,optical and luminescence properties was investi-gated.The Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics pre-sintered at 1625℃for 2 h combined with HIP post-treatment show the high-est in-line transmittance of 75.2%at 611 nm.The photoluminescence(PL)and X-ray excited luminescence(XEL)spectra of the Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)transparent ceramics demonstrate a strong red emission peak at 611 nm due to the^(5)D_(0)→^(7)F_(2) transition of Eu^(3+).The PL,PLE and XEL intensities of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics show a trend of first ascending and then descending with the increase of pre-sintering temperature.The thermally stimulated lumines-cence(TSL)curve of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics presents one high peak at 178 K and two peaks with lower intensities at 253 K and 320 K.The peak at 320 K may be related to oxygen vacancies,and the lumines-cence peak at 178 K is related to defects caused by the valence state changes of Eu^(3+)ions.展开更多
This study investigated the effect of pre-friction surfacing heat treatment of consumable rods and heat input during friction surfacing on the microstructure,mechanical properties,and wear resistance of hypereutectic ...This study investigated the effect of pre-friction surfacing heat treatment of consumable rods and heat input during friction surfacing on the microstructure,mechanical properties,and wear resistance of hypereutectic Al-Si alloy deposited on a commercially pure aluminum substrate.The results show that regardless of the consumable rod’s heat treatment conditions,the coating’s efficiency has increased with the increase in heat input,so the coating efficiency increases by 20%and 30%in the solid solution-treated rod and the artificially aged rod,respectively.By increasing the heat input,the average grain size in the coating fabricated by solid solution-treated rod and artificially aged rod increased from 0.1 to 0.9μm and from 0.2 to 1.3μm,respectively.At constant heat input,the average hardness and wear resistance of the coating created in the solid solution-treated rod are lower than those of the artificially aged rod.By decreasing heat input,the wear loss in the coating fabricated by solid solution-treated rod and artificially aged rod decreased by 10%and 20%,respectively,reaching 0.1 and 0.03μg/m.展开更多
The main objective of this paper focuses on the changes that occur in the strength and microstructural properties of sodium silicate activated fly ash based geopolymer due to varying the sulfate salt and water content...The main objective of this paper focuses on the changes that occur in the strength and microstructural properties of sodium silicate activated fly ash based geopolymer due to varying the sulfate salt and water content.A series of tests including X-ray diffraction,Fourier transform infrared spectroscopy,scanning electron microscopy,physical adsorption and unconfined compressive strength were used to investigate this effect.The results indicate that the higher water content has an adverse effect on the alkali activation and microstructural properties of geopolymer,so the optimum mass ratio of sodium sulfate in alkali-activated geopolymer under different water-to-binder ratios shows a“peak shifting”phenomenon,i.e.,the higher the water-to-binder ratio,the higher the optimum mass ratio.Lower presence of sodium sulfate has no significant effect on the alkali-activated geopolymer systems;higher addition of sodium sulfate,however,could cause the symmetrical stretching vibration of Si—O and the symmetrical stretching vibration of Si—O—Si and Al—O—Si,and promote the formation of N-A-S-H gels.Furthermore,the cement effect of the gel and sodium sulfate aggregate could improve the integrity of pore structure obviously.The maximum strength of geopolymer curing at ambient temperature was 52 MPa.This study obtains the rule that the strength properties of alkali-activated geopolymers vary with the water-to-binder ratio and sodium sulfate content.The feasibility of geopolymer co-activated by sodium sulfate and sodium silicate was investigated,and reference for engineering application of alkali-activated geopolymer in salt-bearing areas was provided.展开更多
In this study,the effect of varied loading ratio(mass of the explosive/mass of flyer plate)on the nature of interface,temperature and pressure developed in aluminum-steel explosive cladding is presented.Increase in th...In this study,the effect of varied loading ratio(mass of the explosive/mass of flyer plate)on the nature of interface,temperature and pressure developed in aluminum-steel explosive cladding is presented.Increase in the loading ratio,R,enhances the pressure developed,kinetic energy utilization and deformation work performed.Interfacial microstructures exhibit the formation of molten layer at few spots,owing to the increase in temperature beyond the melting point of parent alloy.The increase in temperature and the quantum of pressure developed were determined by numerical simulation performed in Ansys AUTODYN by employing smoothed particle hydrodynamics(SPH)method.The positioning of the experimental conditions on the weldability window is presented as well.展开更多
This study aims to improve the mechanical behavior of disintegrated carbonaceous mudstone, which is used as road embankment filler in southwestern China. Triaxial tests were performed on disintegrated carbonaceous mud...This study aims to improve the mechanical behavior of disintegrated carbonaceous mudstone, which is used as road embankment filler in southwestern China. Triaxial tests were performed on disintegrated carbonaceous mudstone modified by fly ash, cement, and red clay. Then the stress-strain relationships and shear strength parameters were analyzed. The microstructure and mineral composition of the materials were identified via scanning electron microscopy and X-ray diffraction. The results show that the stress-strain relationships changed from strain-hardening to strain-softening when disintegrated carbonaceous mudstone was modified with cement. By contrast, the addition of fly ash and red clay did not change the type of stress-strain relationships. The order of these three additives is cement, red clay and fly ash according to their influences on the cohesion. Disintegrated carbonaceous mudstone without cement all showed bulging failures, and that modified with cement exhibited shear failures or bulging-shear failures. The soil particles of the improved soil were well bonded by cementitious substances, so the microstructure was denser and more stable, which highly enhanced the mechanical behavior of disintegrated carbonaceous mudstone. The findings could offer references for the use of carbonaceous mudstone in embankment engineering.展开更多
文摘Sodium-ion batteries(SIBs)have emerged as a promising alternative to commercial lithium-ion batteries be-cause of the similar properties of Li and Na as well as the abundance and accessibility of sodium resources.The devel-opment of anode materials with a high capacity,excellent rate performance,and long cycle life is the key to the indus-trialization of SIBs.Biomass-derived carbon(BDC)anode materials synthesized from resource-rich,low-cost,and re-newable biomass have been extensively researched and their excellent sodium storage performance has been proven,making them the most promising new low-cost and high-performance anode material for SIBs.This review first intro-duces the sources of BDCs,including waste biomass such as plants,animals,and microorganisms,and then describes sev-eral methods for preparing BDC anode materials,including carbonization,chemical activation,and template methods.The storage mechanism and kinetic process of Na^(+)in BDCs are then considered as well as their structure control.The electrochemical properties of sodium-ion storage in BDCs with different structures are examined,and suggestions for future re-search are made.
文摘Pitch is a complex mixture of polycyclic aromatic hydrocarbons and their non-metal derivatives that has a high carbon content.Using pitch as a precursor for carbon materials in alkali metal ion(Li^(+)/Na^(+)/K^(+))batteries has become of great interest.However,its direct pyrolysis often leads to microstructures with a high orientation and small interlayer spacing due to uncontrolled liquid-phase carbonization,resulting in subpar electrochemical performance.It is therefore important to control the microstructures of pitch-derived carbon materials in order to improve their electrochemical properties.We evaluate the latest progress in the development of these materials using various microstructural engineering approaches,highlighting their use in metal-ion batteries and supercapacitors.The advantages and limitations of pitch molecules and their carbon derivatives are outlined,together with strategies for their modification in order to improve their properties for specific applications.Future research possibilities for structure optimization,scalable production,and waste pitch recycling are also considered.
基金National Natural Science Foundation of China(No.41967035)。
文摘Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the reinforcement reliable,this experiment mixed(ultrafine cement)UFC into ordinary cement to form a composite solidify agent.This study aimed to analyze the influence of UFC proportion on the strength of cement-soil in the peat soil environment.Unconfined compressive strength(UCS)and scanning electron microscope(SEM)tests were conducted on samples soaked for 28 and 90 days,respectively.The test results show that without considering the effects of Humic Acid(HA)and Fulvic Acid(FA),incorporating UFC can significantly improve the UCS of cement-soil.The rapid hydration of the fine particles generates a large number of cementitious products,improves the cohesion of the soil skeleton,and fills the pores.However,when the proportion of UFC increases,the aggregate structure formed by a larger quantity of fine particles reduces the hydration rate and degree of cement hydration,making the UCS growth rate of cement-soil insignificant.In the peat soil environment,HA significantly weakened the UCS of cement-soil in both physical and chemical aspects.However,UFC can mitigate the adverse effect of HA on cement-soil by its small particle size,high surface energy,and solid binding ability.In addition,FA has a positive effect on the UCS of cement-soil soaked for 28 days and 90 days.The UFC addition could promote the enhancement effect of FA on cement-soil UCS.SEM test results showed that cement hydration products increased significantly with the increase of UFC proportion,and cementation between hydration products and soil particles was enhanced.The size and connectivity of cement-soil pores were significantly reduced,thereby improving cement-soil structural integrity.
基金supported by the National Natural Science Foundation of China(61774140).
文摘ZnO thin films with varying Ta concentrations were fabricated through magnetron sputtering.The crystallinity and surface morphology of the ZnO films are significantly influenced by the incorporation of Ta,as evidenced by the X-ray diffraction and scanning electron microscopy results.The lattice constants,as determined by X-ray diffraction,contradict the disparity in Ta and Zn ion radii,which is attributed to the impact of interstitial defects.This inconsistency introduces variations in carrier concentration in this experiment compared with prior studies.Subsequent exploration of the luminescent characteristics and emission mechanism of defect levels in Ta-doped ZnO films was conducted through photoluminescence.Furthermore,the factors influencing the bandgap are discussed.
文摘A relatively well-preserved rodent fossil,including its incisors,cheek teeth,and postcranial skeleton,was collected from the Baiyin Obo in Siziwang Banner,Nei Mongol.A multifaceted research approach was undertaken in this study to conduct a comprehensive analysis on the newly discovered specimen.Based on a morphological comparison,the new specimen was identified as Hulgana cf.H.ertnia within the Ischyromyidae family.Incisive enamel microstructure analysis revealed the typical pauciserial enamel structure of Hulgana.Bone histological analysis indicates that the specimen represents a juvenile individual,which is consistent with the ontogenetic stage indicated by dental developmental stage and wear pattern.The application of geometric morphometrics to the calcaneus and bone histology of the femur and phalanx further substantiates the taxonomic classification of Hulgana as a terrestrial and cursorial rodent,exhibiting a degree of fossorial ability.This classification is analogous to that of certain extant cricetids and ground squirrels.
基金Project(2023DJC182)supported by the Department of Science and Technology of Hubei Province,ChinaProjects(51608402,51602229)supported by the National Natural Science Foundation of ChinaProject(2021-2075-38)supported by the Department of Housing and Urban-Rural Development of Hubei Province,China。
文摘Ferrite-rich calcium sulfoaluminate(FCSA)cement is often used in special projects such as marine engineering due to its excellent resistance of seawater attack although the cost is a little high.Ground granulated blast furnace slag(GGBS),a byproduct of industrial production,is used as a mineral admixture to reduce concrete costs and provide excellent performance.This study aimed to investigate the impact of GGBS on the hydration properties of FCSA cement in seawater.Tests were conducted on heat of hydration,compressive strength,mass change,and pH value of pore solution of FCSA cement paste with a water-to-binder ratio of 0.45.X-ray diffraction(XRD)analysis and thermogravimetric analysis were used to determine the hydration products,while mercury intrusion porosimetry(MIP)was used to measure pore structure.The results indicated that the FCSA cement hydration showed a concentrated heat release at early age.The compressive strength of specimens consistently increased over time,where seawater curing enhanced the compressive strength of control samples.The pH value of pore solution decreased to 10.7−10.9 at 90 d when cured in seawater.The primary hydration products of FCSA cement included ettringite,iron hydroxide gel(FH_(3)),and aluminum hydroxide gel(AH_(3)).Moreover,when cured in seawater,Friedel’s salt was formed,which enhanced the compressive strength of the specimen and increased its coefficient of corrosion.Seawater curing gradually increased sample mass,and GGBS refined pore structure while reducing harmful pore proportions.These results suggest that while GGBS can refine pore structure and improve certain aspects of performance,its inclusion may also reduce compressive strength,highlighting the need for a balanced approach in its use for marine applications.
基金Project(IMRI23005)supported by Ordos Science and Technology Bureau,ChinaProjects(52174096,52304110)supported by the National Natural Science Foundation of China。
文摘To investigate the effects of water and cyclic loading on dolomite’s mechanical properties during deep mining,mechanical experiments on non-pressure water absorption and cyclic loading were conducted.The findings reveal that the elastic modulus and Poisson ratio of dolomite fluctuate with increasing water content.The mass of water absorption is positively correlated with time and the water absorption stage can be divided into three stages:accelerated,decelerated,and stabilized stages.During this process,the number of pores in dolomite increases,while the pore diameter initially decreases and then fluctuates.Microscopic analysis shows that the proportion of mesopores first increases and then decreases,while micropores exhibit the opposite trend,and the proportion of macropores fluctuates around 0%.A model diagram of structural evolution during water absorption has been developed.Additionally,the softening process of dolomite’s water absorption strength is categorized into three stages:a relatively stable stage,an accelerated softening stage dominated by mesopore water absorption,and a decelerated softening stage characterized by micropore water absorption.A uniaxial damage constitutive model for dolomite under water influence was established based on the Weibull distribution and Mohr-Coulomb strength criterion,and experimental validation indicates its strong applicability.
基金Project(52374395) supported by the National Natural Science Foundations of ChinaProjects(20210302123135,20210302123163) supported by the Natural Science Foundation of Shanxi Province,China+2 种基金Projects(YDZJSX20231B003,YDZJSX2021A010) supported by the Central Government Guided Local Science and Technology Development Projects,ChinaProject(2022M710541) supported by the China Postdoctoral Science FoundationProjects(202104021301022,202204021301009) supported by the Scientific and Technological Achievements Transformation Guidance Special Project of Shanxi Province,China。
文摘To weaken the basal texture and in-plane anisotropy of magnesium alloy, non-basal slips are pre-enhanced by pre-rolling with a single pass larger strain reduction at elevated temperatures. Then Mg alloy sheets with the thickness of 1 mm are achieved after five passes rolling at 300 ℃. A double peak and disperse basal texture is generated after pre- rolling at higher temperatures when the non-basal slips are more active. So, the texture intensity of pre-rolled samples is reduced. Moreover, the distribution condition of in-grain misorientation axes (a method to analyze the activation of slips) shows that the pyramidal slip is quite active during deformation. After annealing on final rolled sheets, the texture distributions are changed and the intensity of texture reduces obviously due to static recrystallization. In particular, the r-value and in-plane anisotropy of pre-rolled samples are obviously lower than those of sample without pre-rolling.
基金Projects(52171003,52271005)supported by the National Science and Technology Major Project of ChinaProject(KYCX23_3032)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China。
文摘In the process of protecting ferrous materials,aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy.However,the capacity of the sacrificial anode is rather insufficient.In order to solve this problem,the microstructure and electrochemical corrosion properties of Al-8Si-3Fe-xIn alloy under low chlorine conditions were studied.The results show that indium(In)dissolves to form In^(3+)and In^(+)reverse plating on the surface of the bare substrate to form a passivation film defect.When the In content is high,the segregated In forms an activation point in the form of a cathode phase.In activatesτ_(6)phase to form a micro-couple,which improves the non-uniform corrosion.The In-containing corrosion products at the phase boundary hinder the diffusion of Cl−.With an increase of In content,the self-corrosion potential(Ecorr)of the alloy shifts negatively,and the self-corrosion current density(Jcorr)decreases from 6.477μA/cm^(2)to 1.352μA/cm^(2),and then increases gradually.However,when the In content is 0.1%,the Ecorr of the alloy changes from−0.824 V to−0.932 V,and the Jcorr decreases from 6.477μA/cm^(2)to 4.699μA/cm^(2),suggesting that the use of sacrificial anode will give the best effect.
基金Project(52474418)supported by the National Natural Science Foundation of ChinaProject(YDZJSX2022A012)supported by the Central Guiding Local Science and Technology Development Foundation,China。
文摘The research demonstrated that laser powder bed fusion(LPBF)coupled with controlled annealing at 1200°C,could significantly increase the proportion of coincidence site lattice(CSL)grain boundary,thereby achieving an outstanding synergy of enhanced strength and exceptional ductility.The plastic deformation behavior,strain hardening behavior,and fracture behavior of LPBF 316L steel annealing at 1200℃for 20 h were studied through quasi-in-situ tensile process.It was found that LPBF 316L steel formed a certain proportion of deformation twins during the tensile process,and the formation of twins changed the crystal orientation,thus promoting further slip and crystal deformation.The synergistic effect of slip and twin promoted higher plasticity.LPBF process coupled with controlled annealing at 1200°C for 20 h leads to a ultimate tensile strength of 613 MPa and total elongation of 73.8%.
文摘Polyether ether ketone(PEEK)has good mechanical properties.However,its high viscosity when molten limits its use because it is hard to process.PEEK nanocomposites containing both carbon nanotubes(CNTs)and polyether imide(PEI)were pre-pared by a direct wet powder blending method using a vertical injection molding machine.The addition of an optimum amount of PEI lowered the viscosity of the molten PEEK by approximately 50%while producing an increase in the toughness of the nanocom-posites,whose strain to failure increased by 129%,and fracture energy increased by 97%.The uniformly dispersed CNT/PEI powder reduced the processing difficulty of PEEK nanocomposites without affecting the thermal resistance.This improvement of the strength and viscosity of PEEK facilitate its use in the preparation of thermoplastic composites.
文摘In the present study,microstructural evolution,mechanical and creep properties of Al/SiC/Cu composite stripsfabricated via accumulative roll bonding(ARB)process were studied.The obtained results showed the formation of anatomic diffusion layer with thickness of about 17μm at the interface during the ARB under three creep loadingconditions namely 30 MPa at 225℃,35 MPa at 225℃,and 35 MPa at 275℃.An generated intermetallic compoundresulted in a 40%increase of interface thickness near Al.The stress level decreased by 13%at constant temperature withno signi fi cant effect on the interface thickness,and the creep failure time declined by 44%.It was observed that atconstant temperatures,the second slope of the creep curve reached to 39%with increasing stress level,then,it dropped to2%with a little temperature rising.After creep test under 35 MPa at 275℃,the sample displays the presence of 60%Aland 40%Cu,containing brittle Al_(2)Cu intermetallic compound at the interface.Applied temperature and stress had effecton the creep properties,specially increasing the slope of creep curves with higher stresses.
基金Projcet(52279119)supported by the National Natural Science Foundation of ChinaProject(XZ202201ZY0021G)supported by the Science and Technology Planning Project of Xizang Autonomous Region,China+1 种基金Project(2019QZKK0904)supported by the Second Xizang Plateau Scientific Expedition and Research Program of ChinaProject(51922104)supported by the National Natural Science Foundation for Distinguished Young Scholars of China。
文摘To develop suitable grouting materials for water conveyance tunnels in cold regions,firstly,this study investigated the performance evolution of ferrite-rich sulfoaluminate-based composite cement(FSAC grouting material)at 20 and 3℃.The results show that low temperature only delays the strength development of FSAC grouting material within the first 3 d.Then,the effect of four typical early strength synergists on the early properties of FSAC grouting material was evaluated to optimize the early(£1 d)strength at 3℃.The most effective synergist,Ca(HCOO)_(2),which enhances the low-temperature early strength without compromising fluidity was selected based on strength and fluidity tests.Its micro-mechanism was analyzed by XRD,TG,and SEM methods.The results reveal that the most suitable dosage range is 0.3 wt%−0.5 wt%.Proper addition of Ca(HCOO)_(2)changed the crystal morphology of the hydration products,decreased the pore size and formed more compact hydration products by interlocking and overlapping.However,excessive addition of Ca(HCOO)_(2)inhibited the hydration reaction,resulting in a simple and loose structure of the hydration products.The research results have reference value for controlling surrounding rock deformation and preventing water and mud inrushes during the excavation in cold region tunnels.
文摘One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm for bonding time of 20,40,60,and 90 min.The bonding temperature of 860℃ was considered,which is under the β transus temperature of Cp-Ti.During TLP bonding,various intermetallic compounds(IMCs),including Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe),Ti_(2)(Cu,Ag),and Ti_(2)Cu from 304L toward Cp-Ti formed in the joint.Also,on the one side,with the increase in time,further diffusion of elements decreases the blocky IMCs such as Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe)in the 304L diffusion-affected zone(DAZ)and reaction zone,and on the other side,Ti_(2)(Cu,Ag)IMC transformed into fine morphology toward Cp-Ti DAZ.The microhardness test also demonstrated that the(Cr,Fe)_(2)Ti+Ti_(5)Cr_(7)Fe_(17) IMCs in the DAZ on the side of 304L have a hardness value of HV 564,making it the hardest phase.The maximum and minimum shear strength values are equal to 78.84 and 29.0 MPa,respectively.The cleavage pattern dominated fracture surfaces due to the formation of brittle phases in dissimilar joints.
文摘(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the co-precipitation method.Using the synthesized nano-powders as initial material,Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics were fabri-cated by vacuum pre-sintering at different temperatures for 2 h and hot isostatic pressing(HIP)at 1750℃for 3 h in ar-gon.The influence of pre-sintering temperature on the microstructure,optical and luminescence properties was investi-gated.The Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics pre-sintered at 1625℃for 2 h combined with HIP post-treatment show the high-est in-line transmittance of 75.2%at 611 nm.The photoluminescence(PL)and X-ray excited luminescence(XEL)spectra of the Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)transparent ceramics demonstrate a strong red emission peak at 611 nm due to the^(5)D_(0)→^(7)F_(2) transition of Eu^(3+).The PL,PLE and XEL intensities of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics show a trend of first ascending and then descending with the increase of pre-sintering temperature.The thermally stimulated lumines-cence(TSL)curve of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics presents one high peak at 178 K and two peaks with lower intensities at 253 K and 320 K.The peak at 320 K may be related to oxygen vacancies,and the lumines-cence peak at 178 K is related to defects caused by the valence state changes of Eu^(3+)ions.
文摘This study investigated the effect of pre-friction surfacing heat treatment of consumable rods and heat input during friction surfacing on the microstructure,mechanical properties,and wear resistance of hypereutectic Al-Si alloy deposited on a commercially pure aluminum substrate.The results show that regardless of the consumable rod’s heat treatment conditions,the coating’s efficiency has increased with the increase in heat input,so the coating efficiency increases by 20%and 30%in the solid solution-treated rod and the artificially aged rod,respectively.By increasing the heat input,the average grain size in the coating fabricated by solid solution-treated rod and artificially aged rod increased from 0.1 to 0.9μm and from 0.2 to 1.3μm,respectively.At constant heat input,the average hardness and wear resistance of the coating created in the solid solution-treated rod are lower than those of the artificially aged rod.By decreasing heat input,the wear loss in the coating fabricated by solid solution-treated rod and artificially aged rod decreased by 10%and 20%,respectively,reaching 0.1 and 0.03μg/m.
基金Project(51878322)supported by the National Natural Science Foundation of ChinaProject(18YF1FA112)supported by Key Research and Development Program of Gansu Province,China。
文摘The main objective of this paper focuses on the changes that occur in the strength and microstructural properties of sodium silicate activated fly ash based geopolymer due to varying the sulfate salt and water content.A series of tests including X-ray diffraction,Fourier transform infrared spectroscopy,scanning electron microscopy,physical adsorption and unconfined compressive strength were used to investigate this effect.The results indicate that the higher water content has an adverse effect on the alkali activation and microstructural properties of geopolymer,so the optimum mass ratio of sodium sulfate in alkali-activated geopolymer under different water-to-binder ratios shows a“peak shifting”phenomenon,i.e.,the higher the water-to-binder ratio,the higher the optimum mass ratio.Lower presence of sodium sulfate has no significant effect on the alkali-activated geopolymer systems;higher addition of sodium sulfate,however,could cause the symmetrical stretching vibration of Si—O and the symmetrical stretching vibration of Si—O—Si and Al—O—Si,and promote the formation of N-A-S-H gels.Furthermore,the cement effect of the gel and sodium sulfate aggregate could improve the integrity of pore structure obviously.The maximum strength of geopolymer curing at ambient temperature was 52 MPa.This study obtains the rule that the strength properties of alkali-activated geopolymers vary with the water-to-binder ratio and sodium sulfate content.The feasibility of geopolymer co-activated by sodium sulfate and sodium silicate was investigated,and reference for engineering application of alkali-activated geopolymer in salt-bearing areas was provided.
文摘In this study,the effect of varied loading ratio(mass of the explosive/mass of flyer plate)on the nature of interface,temperature and pressure developed in aluminum-steel explosive cladding is presented.Increase in the loading ratio,R,enhances the pressure developed,kinetic energy utilization and deformation work performed.Interfacial microstructures exhibit the formation of molten layer at few spots,owing to the increase in temperature beyond the melting point of parent alloy.The increase in temperature and the quantum of pressure developed were determined by numerical simulation performed in Ansys AUTODYN by employing smoothed particle hydrodynamics(SPH)method.The positioning of the experimental conditions on the weldability window is presented as well.
基金Projects(51908069, 51908073, 51838001, 51878070) supported by the National Natural Science Foundation of ChinaProject(2019SK2171) supported by the Key Research and Development Program of Hunan Province, China+3 种基金Project(2019IC04) supported by the Double First-Class Scientific Research International Cooperation Expansion Project of Changsha University of Science & Technology,ChinaProject(kfj190605) supported by the Open Fund of Engineering Laboratory of Spatial Information Technology of Highway Geological Disaster Early Warning in Hunan Province (Changsha University of Science & Technology), ChinaProject(kq1905043) supported by the Training Program for Excellent Young Innovators of Changsha, ChinaProject(SJCX202017) supported by the Practical Innovation Program for Graduates of Changsha University of Science & Technology, China。
文摘This study aims to improve the mechanical behavior of disintegrated carbonaceous mudstone, which is used as road embankment filler in southwestern China. Triaxial tests were performed on disintegrated carbonaceous mudstone modified by fly ash, cement, and red clay. Then the stress-strain relationships and shear strength parameters were analyzed. The microstructure and mineral composition of the materials were identified via scanning electron microscopy and X-ray diffraction. The results show that the stress-strain relationships changed from strain-hardening to strain-softening when disintegrated carbonaceous mudstone was modified with cement. By contrast, the addition of fly ash and red clay did not change the type of stress-strain relationships. The order of these three additives is cement, red clay and fly ash according to their influences on the cohesion. Disintegrated carbonaceous mudstone without cement all showed bulging failures, and that modified with cement exhibited shear failures or bulging-shear failures. The soil particles of the improved soil were well bonded by cementitious substances, so the microstructure was denser and more stable, which highly enhanced the mechanical behavior of disintegrated carbonaceous mudstone. The findings could offer references for the use of carbonaceous mudstone in embankment engineering.
