As the carrier of charge storage,the electrode determines the efficiency of the energy conversion reaction between the battery and the substance.However,with the continuous development of scientific research,electrode...As the carrier of charge storage,the electrode determines the efficiency of the energy conversion reaction between the battery and the substance.However,with the continuous development of scientific research,electrode preparation is still facing complex technical problems,and it is difficult to achieve a balance in performance,cost,and technology.Based on the ion dissolution and deposition behavior of Mn^(2+)/MnO_(2) and Al^(3+)/Al,a novel cathode-free aqueous ion dissolution/deposition battery is designed,which can contribute 15 mAh at 16 cm^(2) in a voltage window of 0.5-1.8 V.The charge storage and the attenuation mechanism are systematically investigated.The battery model with compensable electrolyte was constructed,and the cycle characteristics of the cathode-free aqueous ion dissolution/deposition battery were optimized,which could achieve 1000 h continuous operation.This system provides a low-cost and high-safety solution for future high-energy density and large-scale energy storage.Future research will focus on optimizing electrolytes,controlling deposition morphology,and improving interface stability to further promote the commercialization of cathode-free batteries.展开更多
The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control...The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control during debris flows is crucial but difficult.Herein,an eco-friendly control system featuring anchoring natural boulders(NBs)with(negative Poisson's ratio)NPR anchor cables is proposed to form an NB-NPR baffle.A series of flume experiments are conducted to verify the effect of NB-NPR baffles on controlling debris flow impact.The deployment of NB-NPR baffles substantially influences the kinematic behavior of a debris flow,primarily in the form of changes in the depositional properties and impact intensities.The results show that the NB-NPR baffle matrix successfully controls boulder mobility and exhibits positive feedback on solid particle deposition.The NB-NPR baffle group exhibits a reduction in peak impact force ranging from 29%to 79%compared to that of the control group in the basic experiment.The NPR anchor cables play a significant role in the NB-NPR baffle by demonstrating particular characteristics,including consistent resistance,large deformation,and substantial energy absorption.The NB-NPR baffle innovatively utilizes the natural boulders in a debris flow gully by converting destructive boulders into constructive boulders.Overall,this research serves as a basis for future field experiments and applications.展开更多
MnO_(2)has attracted great interest in working as the cathode of zinc ion batteries.However,the development of high-capacity,high-energy-density,and durable manganese-based cathodes with an easy synthesis strategy and...MnO_(2)has attracted great interest in working as the cathode of zinc ion batteries.However,the development of high-capacity,high-energy-density,and durable manganese-based cathodes with an easy synthesis strategy and proper energy storage mechanism remains an ongoing challenge.Herein,a facile plasmainduced strategy was demonstrated to introduce oxygen vacancies into theε-MnO_(2),and the obtained oxygen vacancies-richε-MnO_(2)nanosheets(ε-MnO_(2-x))show satisfactory electrochemical performances.Furthermore,an appropriate energy storage mechanism for dissolution/deposition was proposed.Thanks to a synergistic effect of the oxygen vacancies inε-MnO_(2)nanosheets and the exposed free-standing collector for Mn^(2+) dissolution/deposition,theε-MnO_(2-x) nanosheets electrode delivers a remarkable capacity(337 mAh g^(-1)at 0.1 A g^(-1))and exhibits an ultrahigh energy density of 462 Wh kg^(-1)(based on the weights of the cathode active material).Furthermore,impressive durability with 85.9%capacity retention after 1000 cycles was obtained.The superior electrochemical performance makes the plasma-induced strategy promising for designing advanced metal oxide electrode materials for high-performance aqueous zinc ion batteries.展开更多
The crack initiation and early propagation are of great significance to the overall fatigue life of material.In order to investigate the anisotropic fracture behavior of laser metal deposited Ti-6Al-4V alloy(LMD Ti64)...The crack initiation and early propagation are of great significance to the overall fatigue life of material.In order to investigate the anisotropic fracture behavior of laser metal deposited Ti-6Al-4V alloy(LMD Ti64)during the early stage,the fourpoint bending fatigue test was carried out on specimens of three different directions,as well as the forged specimens.The results indicate the anisotropic crack initiation and early propagation of LMD Ti64.The direction perpendicular to the deposition direction exhibits a better fatigue resistance than the other two.The crack initiation position and propagation path are dominated by the microstructure in the vicinity of U-notch.LMD Ti64 has a typical small crack effect,and the early crack propagation velocities in three directions are similar.Affected by the slip system of LMD Ti64,secondary cracks frequently occur,which are often found to have an angle of 60°to the main crack.The electron backscatter diffraction analysis indicates that LMD Ti64 has preferred orientations,i.e.,strong 0001//Z texture and 001//Z texture.Their crystallographic orientation will change as the direction of columnarβgrains turns over,resulting in the fatigue anisotropy of LMD Ti64 in crack initiation and early crack propagation process.展开更多
Bauxite residue is a highly alkaline waste containing soluble alkaline anions,which can cause environmental concerns.The optimal leaching conditions,distribution of alkaline anions,types of pivotal alkaline anions and...Bauxite residue is a highly alkaline waste containing soluble alkaline anions,which can cause environmental concerns.The optimal leaching conditions,distribution of alkaline anions,types of pivotal alkaline anions and their dissolution behaviors were investigated based on the combination of single factors-orthogonal experiments and leaching stage experiment.Using a two-stage leaching,86%of the soluble alkaline anions(CO3^2-,HCO4^-,Al(OH)4^-,OH^-)were leached with a L/S ratio of 2 mL/g,at 30℃,over 23 h.During the first stage of leaching,approximately 88%of alkaline anions were leached from the dissolution of free alkali(Na OH,carbonate,bicarbonate,NaAl(OH)4)with the rest originating from the dissolution of alkaline minerals(calcite,cancrinite and hydrogarnet).Supernatant alkalinity was 69.78 mmol/L with CO3^2-accounting for 75%.Furthermore,carbonate leaching was controlled by solid film diffusion using the Stumm Model with an apparent activation energy of 10.24 kJ/mol.展开更多
The supersonic laser deposition （SLD） is a new fabrication process which combines the supersonic powder stream found in cold spray with laser heating of the deposition zone. Because of the instantaneity of particles...The supersonic laser deposition （SLD） is a new fabrication process which combines the supersonic powder stream found in cold spray with laser heating of the deposition zone. Because of the instantaneity of particles impact, the deformation behaviors and the adhesion behaviors of particles impacted on the substrate by SI.D cannot be well investigated through experiments. Therefore, a finite elemen! model was developed to solve the problems above. Meanwhile, the heat effect of the substrate heated by laser was discussed. The effective plastic strain and the effec- tive stress between the particle and substrate at different laser preheal temperatures were studied. The results show that laser depositing temperatures of 1 000 and 1 100 ℃ on substrate would be the optimized for the bonding of parti- cles and substrate. In addition, the simulation results conformed to experimental results.展开更多
ESD (electrospark deposition) is a promising process to produce hard and wear-resisting coatings on metallic substrates. In this paper microstructure and interfacial characteristics of the WC92-Co8 coated on titanium ...ESD (electrospark deposition) is a promising process to produce hard and wear-resisting coatings on metallic substrates. In this paper microstructure and interfacial characteristics of the WC92-Co8 coated on titanium and carbon steel are presented. A metallurgical bonding between the coating and substrate is obtained. The Ti element was found to distribute in WC92-Co8 at the metal pool, as well as the interface by diffusion. Some new phases were produced in the coating layer due to the chemical reaction during the ESD process. Experimental observation and thermodynamic analysis were utilized to study the mechanism of ESD.展开更多
This work focused on the deposition characteristics and wear behavior of Ni-coated graphite mixed with40 vol.% Al（Ni-Gr/Al） composite coatings sprayed on an Al alloy and a steel substrate by cold spraying（CS）. The...This work focused on the deposition characteristics and wear behavior of Ni-coated graphite mixed with40 vol.% Al（Ni-Gr/Al） composite coatings sprayed on an Al alloy and a steel substrate by cold spraying（CS）. The morphology of the flattened Ni-Gr particles was examined by single-impact tests. Crosssectional microstructure and wear performance of the Ni-Gr/Al composite coatings were studied. Results showed that a larger number of Ni-Gr particles were finally bonded with the steel substrate, whereas many craters existed on the Al alloy substrate after the single-impact tests. The coating on the steel substrate had a high thickness, high graphite content and low coeficient of friction（COF） compared to those on the Al alloy substrate. In addition, the CS coatings presented a homogeneous distribution and uniform morphology of graphite, and a comparative COF to that of conventional thermal sprayed coatings. It was shown that CS could avoid the decomposition and transformation of graphite phase.展开更多
In order to provide practical fundamental data for rare-earth elements （REEs） recovery from phosphoric acid and to betterunderstand REEs behavior during the phosphoric acid evaporation process, the solubilities of R...In order to provide practical fundamental data for rare-earth elements （REEs） recovery from phosphoric acid and to betterunderstand REEs behavior during the phosphoric acid evaporation process, the solubilities of REEs in phosphoric acid with variousconcentrations of phosphorus at different temperatures were measured. A simple linear model between REEs solubility andphosphoric acid concentration is built and the experimental data are found to fit it very well （R2〉0.94）. Hydrogen-ion concentration isfound to be the predominant factor controlling the solubility of REEs in phosphoric acid. In addition, the solubility of REEs inphosphoric acid is found to sharply decrease with increasing temperature, which can be attributed to the increase of the Gibbs energyof the REEPO4 dissolution reaction or the restraint of the disassociation of phosphoric acid molecules owing to the elevatedtemperature.展开更多
Analysis on the deposition behavior of spray on deposition surface was made and an optimization method for the movement parameters （u, ω） of substrate was obtained. Simultaneously, a mathematical model of growth of...Analysis on the deposition behavior of spray on deposition surface was made and an optimization method for the movement parameters （u, ω） of substrate was obtained. Simultaneously, a mathematical model of growth of tubular preform, specifically aimed at the kind of atomizer that is fixed and with a tilt angle was established. By in- tegrating the optimization method and the mathematical model, the growth process and shape of preform were simu- lated. The results show that the tilt angle of atomizer plays an important role on the dimensions and shapes of tubular preforms and it can provide a guidance for the development of spray forming equipment.展开更多
The dissolution behaviors of Ta2O5,Nb2O5 and their mixture in KOH and H2O system were investigated.A L9(34) orthogonal design was used to study the effects of reaction temperature,mass ratio of KOH to Ta2O5,and reacti...The dissolution behaviors of Ta2O5,Nb2O5 and their mixture in KOH and H2O system were investigated.A L9(34) orthogonal design was used to study the effects of reaction temperature,mass ratio of KOH to Ta2O5,and reaction time on the dissolution rate of tantalum.It was found that the effect of reaction temperature on the dissolution rate of tantalum was much greater than that of the other factors.The results of factorial experiments showed that Ta2O5 was mainly transformed into insoluble potassium tantalate at low temperature(350 ℃) and transformed into soluble potassium tantalate at high temperature(450 ℃).The insoluble potassium tantalate was analyzed by XRD,which was proved to be KTaO3.Differently,almost all Nb2O5 was transformed into soluble potassium niobate at 350-450℃.As for the mixture of Ta2O5 and Nb2O5,the dissolution rate of tantalum increased and the dissolution rate of niobium decreased as an interaction existed between niobium and tantalum.And increasing the mole ratio of Nb2O5 to Ta2O5 in the mixture was beneficial to the dissolution of both Ta2O5 and Nb2O5.In addition,the mechanism of the interaction between niobium and tantalum was also investigated through phase and chemical analysis.展开更多
Directed energy deposition has been used to repair superalloy components in aero engines and gas turbines.However,the microstructure and properties are generally inhomogeneous in components because of the different pr...Directed energy deposition has been used to repair superalloy components in aero engines and gas turbines.However,the microstructure and properties are generally inhomogeneous in components because of the different processing histories.Here,the microstructures and wear behavior of different zones(substrate,HAZ,and deposit)are investigated for the IC10 directionally solidified superalloy repaired by the directed energy deposition process.It is found that the microstructure of the deposited layers is strongly textured with a<001>-fiber texture in the building direction,and the texture intensity is continuously increased along the building direction.Two kinds ofγ’phase(primary and secondaryγ’phase)can be found in the heat-affected zone(HAZ),and the average size of primaryγ’phase is smaller than that in the substrate due to liquation.In the deposit layers,the size ofγ’phase is much smaller than those in the substrate and the primaryγ’phase of HAZ;both size and the fraction of theγ’phase decreases with the increase of building height.The wear rate of the substrate is the smallest,indicating the best wear resistance;while the wear rate of HAZ is the largest,indicating the worst wear resistance in the repaired sample.The wear rates in the deposit layers increase from the bottom to the top zones,showing a decreasing wear resistance.Abrasive wear is found to be the dominant wear mechanism of the repaired alloy,and the resistance to which is closely related to the fraction ofγ’phase in the microstructure.The understanding of the influence of microstructure on wear resistance allows for a more informed application of inhomogeneous superalloy components repaired by directed energy deposition in industry.展开更多
An overview of the advances in studies on tribology of molecular deposition （MD） films is presented here to summarize the studies of nanofrictional properties, adhesion, wear and mechanical behavior, as well as the ...An overview of the advances in studies on tribology of molecular deposition （MD） films is presented here to summarize the studies of nanofrictional properties, adhesion, wear and mechanical behavior, as well as the molecular dynamics simulation of nanotribological properties of the film in the last decade. Some key research topics which need to be investigate further are addressed.展开更多
The Hadamengou gold deposit is located in western part of the northern margin of the North China craton. It is a hydrothermal deposit related to alkaline magmatism. Dissolution of Au, Fe from pyrite and iron oxide （i...The Hadamengou gold deposit is located in western part of the northern margin of the North China craton. It is a hydrothermal deposit related to alkaline magmatism. Dissolution of Au, Fe from pyrite and iron oxide （including magnetite and hematite） individual minerals in the three main types of ore shows： in iron oxides （magnetite and hematite）, Au and Fe were dissolved simultaneously and their solubilities are positively correlated, which means Au is mainly chemical-bonded （lattice gold） and/or colloidal-adsorbed in iron oxides; while in pyrite, on the contrary, Au dissolution obviously lags behind Fe and the solubility of Au shows negative relationship with that of Fe, which indicates Au is mainly hosted as grains of elemental gold （or native gold） within pyrite. Previous studies revealed that the Hadamengou gold deposit is characterized by intensive K-feldspathization and holds high content of iron oxides occasionally replaced by sulfides, which was caused by oxidizing K-enriched alkaline fluids under a stretching geodynamic setting. These geological features, together with the high Au-content in iron oxides, comparable with that of the Olympic Dam deposit in South Australia, suggest that this deposit is the first example of iron oxide-type gold deposits in China.展开更多
Lead(Pb) coprecipitation with jarosite is common in natural and engineered environments,such as acid mine drainage(AMD) sites and hydrometallurgical industry. Despite the high relevance for environmental impact, few s...Lead(Pb) coprecipitation with jarosite is common in natural and engineered environments,such as acid mine drainage(AMD) sites and hydrometallurgical industry. Despite the high relevance for environmental impact, few studies have examined the exact interaction of Pb with jarosite and the dissolution behavior of each phase. In the present work, we demonstrate that Pb mainly interacts with jarosite in four modes, namely incorporation, occlusion,physically mixing, and chemically mixing. For comparison, the four modes of Pb-bearing natrojarosite were synthesized and characterized separately. Batch dissolution experiments were undertaken on these synthetic Pb-bearing natrojarosites under pH_(2) to simulate the AMD environments. The introduction of Pb decreases the final Fe releasing efficiency of jarosite-type compounds from 18.18% to 3.45%-5.01%, showing a remarkable inhibition of their dissolution. For Pb releasing behavior, PbSO_(4) dissolves in preference to Pb-substituted natrojarosite, i.e.,(Na, Pb)-jarosite, which primarily results in the sharp increase of Pb releasing concentration(> 40 mg/L). PbSO_(4) occlusion by jarosite-type compounds can significantly reduce the release of Pb. The results of this study could provide useful information regarding Fe and Pb cycling in acidic natural and engineered environments.展开更多
The friction behavior of the hot filament chemical vapor deposition(HFCVD)diamond film plays a critical role on its applications in mechanical fields and largely depends on the environment.Studies on the tribological ...The friction behavior of the hot filament chemical vapor deposition(HFCVD)diamond film plays a critical role on its applications in mechanical fields and largely depends on the environment.Studies on the tribological properties of HFCVD diamond films coated on Co-cemented tungsten carbide(WC-Co)substrates are rarely reported in available literatures,especially in the water lubricating conditions.In this paper,conventional microcrystalline diamond(MCD)and fine-grained diamond(FGD)films are deposited on WC-Co substrates and their friction properties are evaluated on a reciprocating ball-on-plate tribometer,where they are brought to slide against ball-bearing steel and copper balls in dry and water lubricating conditions.Scanning electron microscopy(SEM),atomic force microscopy(AFM),surface profilometer and Raman spectroscopy are adopted to characterize as-deposited diamond films;SEM and energy dispersive X-ray(EDX)are used to investigate the worn region on the surfaces of both counterface balls and diamond films.The research results show that the friction coefficient of HFCVD diamond films always starts with a high initial value,and then gradually transits to a relative stable state.For a given counterface and a sliding condition,the FGD film presents lower stable friction coefficients by 0.02-0.03 than MCD film.The transferred materials adhered on sliding interface are supposed to have predominate effect on the friction behaviors of HFCVD diamond films.Furthermore,the effect of water lubricating on reducing friction coefficient is significant.For a given counterpart,the stable friction coefficients of MCD or FGD films reduce by about 0.07-0.08 while sliding in the water lubricating condition,relative to in dry sliding condition.This study is beneficial for widespread applications of HFCVD diamond coated mechanical components and adopting water lubricating system,replacing ofoil lubricating,in a variety of mechanical processing fields to implement the green production process.展开更多
In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it i...In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it is feasible to dissolve gold in thiourea-alkaline medium. A thermodynamic study was conducted by chemical speciation using the method of Ro-jas-Hernández, together with an electrochemical study where the electric potential was swept in the anodic direction. The main results of the thermodynamic study were that formamidine disulfide (FDS) and sulfinic compounds (S.C.) prevail at alkaline pH;by increasing the initial concen-tration of thiourea at alkaline pH, the presence of the gold complex is al-most zero for any initial concentration of thiourea. By including sodium sulfite in the gold-thiourea system, it was possible to obtain the Au(I)-TU complex at alkaline pH, with a presence of 95.13%. Electrochemical tests allowed verifying that in the absence of sodium sulfite the dissolution of gold in an alkaline medium is very slow but adding sodium sulfite im-provements become evident in the dissolution of the metal. Therefore, sodium sulfite catalyzes the gold dissolution process and stabilizes the thiourea. With this study it was possible to establish the feasibility of using thiourea in an alkaline medium for the dissolution of gold, and the conditions under which it is possible to dissolve the gold in that medium. With these fundamentals and conditions, it is now possible to move forward to test this system for minerals and/or concentrates containing gold.展开更多
Abstract: Based on the element life and death theory of finite element analysis(FEA), a three-dimensional multi-track and multi-layer model for laser metal deposition shaping(LMDS) was developed with ANSYS parametric ...Abstract: Based on the element life and death theory of finite element analysis(FEA), a three-dimensional multi-track and multi-layer model for laser metal deposition shaping(LMDS) was developed with ANSYS parametric design language(APDL), and detailed numerical simulations of temperature and thermal stress were conducted. Among those simulations, long-edge parallel reciprocating scanning method was introduced. The distribution regularities of temperature, temperature gradient, Von Mise’s effective stress, X-directional, Y-directional and Z-directional thermal stresses were studied. LMDS experiments were carried out with nickel-based superalloy using the same process parameters as those in simulation. The measured temperatures of molten pool are in accordance with the simulated results. The crack engendering and developing regularities of samples show good agreement with the simulation results.展开更多
The properties orAl based nanocomposite metal foams and their corrosion behaviors were investigated in this study. For this, the composite metal foams with different relative densities （porosity） reinforced with alu...The properties orAl based nanocomposite metal foams and their corrosion behaviors were investigated in this study. For this, the composite metal foams with different relative densities （porosity） reinforced with alumina nanoparticles were prepared using a powder me- tallurgy-based sintering-dissolution process （SDP） and NaC1 particles were used as space holders. Then, the effect of nanoparticle rein- forcement and different amounts of NaC1 space holders （corresponding porosity） on the microstructure, morphology, density, hardness, and electrochemical specifications of the samples were investigated. It was found that as the relative density increased from 60% to 70%, the wall thickness increased from about 200 to 300 pro, which led to a decrease in pore size. Also, the addition of nanoparticle reinforcement and the increased relative density result in increasing metal foam hardness. Moreover, electrochemical test results indicated that increasing the A1203 content reduced the corrosion rate, but increasing the porosity enhanced it.展开更多
This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential ox...This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential oxidation pathway of molybdenum into high-valence ions(Mo^(6+),Mo^(5+),Mo^(4+))under vary-ing electrolysis potentials.Electrochemical Impedance Spectroscopy(EIS)demonstrated that the dissolu-tion is governed by both charge transfer and diffusion mechanisms,with reduced impedance at higher potentials facilitating molybdenum dissolution.The reduction behavior of dissolved molybdenum ions was further explored using cyclic voltammetry(CV)and square wave voltammetry(SWV),confirming a multi-step reduction process controlled by diffusion and high reversibility.Nucleation studies using chronoamperometry established that molybdenum deposition follows an instantaneous nucleation mech-anism.Morphological analysis of cathodic deposits revealed that current density significantly influences particle size,transitioning from nano-sized spherical particles to larger equiaxed crystals with increasing current density.These findings provide a comprehensive understanding of molybdenum’s electrochemical properties in molten salts,offering valuable insights for optimizing electrolysis processes and advancing molybdenum-based material production.展开更多
基金support provided by the Natural Science Foundation of Jilin Province(YDZJ202401316ZYTS)the Innovation Laboratory Development Program of the Education Department of Jilin Province and the Industry and Information Technology Department of Jilin Province,China(The Joint Laboratory of MXene Materials)the MXene Research Support Plan of Jilin 11 Technology Co.,Ltd.,China,and Future(Jilin)Material Technology Co.,Ltd.
文摘As the carrier of charge storage,the electrode determines the efficiency of the energy conversion reaction between the battery and the substance.However,with the continuous development of scientific research,electrode preparation is still facing complex technical problems,and it is difficult to achieve a balance in performance,cost,and technology.Based on the ion dissolution and deposition behavior of Mn^(2+)/MnO_(2) and Al^(3+)/Al,a novel cathode-free aqueous ion dissolution/deposition battery is designed,which can contribute 15 mAh at 16 cm^(2) in a voltage window of 0.5-1.8 V.The charge storage and the attenuation mechanism are systematically investigated.The battery model with compensable electrolyte was constructed,and the cycle characteristics of the cathode-free aqueous ion dissolution/deposition battery were optimized,which could achieve 1000 h continuous operation.This system provides a low-cost and high-safety solution for future high-energy density and large-scale energy storage.Future research will focus on optimizing electrolytes,controlling deposition morphology,and improving interface stability to further promote the commercialization of cathode-free batteries.
基金financial support from the National Natural Science Foundation of China(Grant No.41941018).
文摘The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control during debris flows is crucial but difficult.Herein,an eco-friendly control system featuring anchoring natural boulders(NBs)with(negative Poisson's ratio)NPR anchor cables is proposed to form an NB-NPR baffle.A series of flume experiments are conducted to verify the effect of NB-NPR baffles on controlling debris flow impact.The deployment of NB-NPR baffles substantially influences the kinematic behavior of a debris flow,primarily in the form of changes in the depositional properties and impact intensities.The results show that the NB-NPR baffle matrix successfully controls boulder mobility and exhibits positive feedback on solid particle deposition.The NB-NPR baffle group exhibits a reduction in peak impact force ranging from 29%to 79%compared to that of the control group in the basic experiment.The NPR anchor cables play a significant role in the NB-NPR baffle by demonstrating particular characteristics,including consistent resistance,large deformation,and substantial energy absorption.The NB-NPR baffle innovatively utilizes the natural boulders in a debris flow gully by converting destructive boulders into constructive boulders.Overall,this research serves as a basis for future field experiments and applications.
基金NSFC(Nos.51702123,51472110)the Shandong Province Higher Educational Youths Innovation Science and Technology Program(No.2019KJA018)the University of Jinan Science and Technology Planning Project(No.XKY2034)。
文摘MnO_(2)has attracted great interest in working as the cathode of zinc ion batteries.However,the development of high-capacity,high-energy-density,and durable manganese-based cathodes with an easy synthesis strategy and proper energy storage mechanism remains an ongoing challenge.Herein,a facile plasmainduced strategy was demonstrated to introduce oxygen vacancies into theε-MnO_(2),and the obtained oxygen vacancies-richε-MnO_(2)nanosheets(ε-MnO_(2-x))show satisfactory electrochemical performances.Furthermore,an appropriate energy storage mechanism for dissolution/deposition was proposed.Thanks to a synergistic effect of the oxygen vacancies inε-MnO_(2)nanosheets and the exposed free-standing collector for Mn^(2+) dissolution/deposition,theε-MnO_(2-x) nanosheets electrode delivers a remarkable capacity(337 mAh g^(-1)at 0.1 A g^(-1))and exhibits an ultrahigh energy density of 462 Wh kg^(-1)(based on the weights of the cathode active material).Furthermore,impressive durability with 85.9%capacity retention after 1000 cycles was obtained.The superior electrochemical performance makes the plasma-induced strategy promising for designing advanced metal oxide electrode materials for high-performance aqueous zinc ion batteries.
基金National Natural Science Foundation of China(12172292,12072287)。
文摘The crack initiation and early propagation are of great significance to the overall fatigue life of material.In order to investigate the anisotropic fracture behavior of laser metal deposited Ti-6Al-4V alloy(LMD Ti64)during the early stage,the fourpoint bending fatigue test was carried out on specimens of three different directions,as well as the forged specimens.The results indicate the anisotropic crack initiation and early propagation of LMD Ti64.The direction perpendicular to the deposition direction exhibits a better fatigue resistance than the other two.The crack initiation position and propagation path are dominated by the microstructure in the vicinity of U-notch.LMD Ti64 has a typical small crack effect,and the early crack propagation velocities in three directions are similar.Affected by the slip system of LMD Ti64,secondary cracks frequently occur,which are often found to have an angle of 60°to the main crack.The electron backscatter diffraction analysis indicates that LMD Ti64 has preferred orientations,i.e.,strong 0001//Z texture and 001//Z texture.Their crystallographic orientation will change as the direction of columnarβgrains turns over,resulting in the fatigue anisotropy of LMD Ti64 in crack initiation and early crack propagation process.
基金Project(41371475)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare Industry
文摘Bauxite residue is a highly alkaline waste containing soluble alkaline anions,which can cause environmental concerns.The optimal leaching conditions,distribution of alkaline anions,types of pivotal alkaline anions and their dissolution behaviors were investigated based on the combination of single factors-orthogonal experiments and leaching stage experiment.Using a two-stage leaching,86%of the soluble alkaline anions(CO3^2-,HCO4^-,Al(OH)4^-,OH^-)were leached with a L/S ratio of 2 mL/g,at 30℃,over 23 h.During the first stage of leaching,approximately 88%of alkaline anions were leached from the dissolution of free alkali(Na OH,carbonate,bicarbonate,NaAl(OH)4)with the rest originating from the dissolution of alkaline minerals(calcite,cancrinite and hydrogarnet).Supernatant alkalinity was 69.78 mmol/L with CO3^2-accounting for 75%.Furthermore,carbonate leaching was controlled by solid film diffusion using the Stumm Model with an apparent activation energy of 10.24 kJ/mol.
基金Item Sponsored by National Natural Science Foundation of China(51271170)Ministry of Science and Technology InternationalCooperation Projects of China(KM-JD-2011010)
文摘The supersonic laser deposition （SLD） is a new fabrication process which combines the supersonic powder stream found in cold spray with laser heating of the deposition zone. Because of the instantaneity of particles impact, the deformation behaviors and the adhesion behaviors of particles impacted on the substrate by SI.D cannot be well investigated through experiments. Therefore, a finite elemen! model was developed to solve the problems above. Meanwhile, the heat effect of the substrate heated by laser was discussed. The effective plastic strain and the effec- tive stress between the particle and substrate at different laser preheal temperatures were studied. The results show that laser depositing temperatures of 1 000 and 1 100 ℃ on substrate would be the optimized for the bonding of parti- cles and substrate. In addition, the simulation results conformed to experimental results.
文摘ESD (electrospark deposition) is a promising process to produce hard and wear-resisting coatings on metallic substrates. In this paper microstructure and interfacial characteristics of the WC92-Co8 coated on titanium and carbon steel are presented. A metallurgical bonding between the coating and substrate is obtained. The Ti element was found to distribute in WC92-Co8 at the metal pool, as well as the interface by diffusion. Some new phases were produced in the coating layer due to the chemical reaction during the ESD process. Experimental observation and thermodynamic analysis were utilized to study the mechanism of ESD.
基金financially supported by the National Natural Science Foundation of China(No.51574196)the 111 Project(No.B08040)+1 种基金the support from programs of China Scholarship Council(No.201404490058)Marie-Curie(No.268696)
文摘This work focused on the deposition characteristics and wear behavior of Ni-coated graphite mixed with40 vol.% Al（Ni-Gr/Al） composite coatings sprayed on an Al alloy and a steel substrate by cold spraying（CS）. The morphology of the flattened Ni-Gr particles was examined by single-impact tests. Crosssectional microstructure and wear performance of the Ni-Gr/Al composite coatings were studied. Results showed that a larger number of Ni-Gr particles were finally bonded with the steel substrate, whereas many craters existed on the Al alloy substrate after the single-impact tests. The coating on the steel substrate had a high thickness, high graphite content and low coeficient of friction（COF） compared to those on the Al alloy substrate. In addition, the CS coatings presented a homogeneous distribution and uniform morphology of graphite, and a comparative COF to that of conventional thermal sprayed coatings. It was shown that CS could avoid the decomposition and transformation of graphite phase.
基金Project(51674036)supported by the National Natural Science Foundation of ChinaProject(Z161100004916108)supported by the Beijing Nova Program,China
文摘In order to provide practical fundamental data for rare-earth elements （REEs） recovery from phosphoric acid and to betterunderstand REEs behavior during the phosphoric acid evaporation process, the solubilities of REEs in phosphoric acid with variousconcentrations of phosphorus at different temperatures were measured. A simple linear model between REEs solubility andphosphoric acid concentration is built and the experimental data are found to fit it very well （R2〉0.94）. Hydrogen-ion concentration isfound to be the predominant factor controlling the solubility of REEs in phosphoric acid. In addition, the solubility of REEs inphosphoric acid is found to sharply decrease with increasing temperature, which can be attributed to the increase of the Gibbs energyof the REEPO4 dissolution reaction or the restraint of the disassociation of phosphoric acid molecules owing to the elevatedtemperature.
基金Sponsored by National Natural Science Foundation of China (50474082)
文摘Analysis on the deposition behavior of spray on deposition surface was made and an optimization method for the movement parameters （u, ω） of substrate was obtained. Simultaneously, a mathematical model of growth of tubular preform, specifically aimed at the kind of atomizer that is fixed and with a tilt angle was established. By in- tegrating the optimization method and the mathematical model, the growth process and shape of preform were simu- lated. The results show that the tilt angle of atomizer plays an important role on the dimensions and shapes of tubular preforms and it can provide a guidance for the development of spray forming equipment.
基金Project(2009AA06Z103) supported by the National High-tech Research and Development Program of ChinaProject(51004094) supported by the National Natural Science Foundation of ChinaProject(2007CB613501) supported by the National Basic Research Program of China
文摘The dissolution behaviors of Ta2O5,Nb2O5 and their mixture in KOH and H2O system were investigated.A L9(34) orthogonal design was used to study the effects of reaction temperature,mass ratio of KOH to Ta2O5,and reaction time on the dissolution rate of tantalum.It was found that the effect of reaction temperature on the dissolution rate of tantalum was much greater than that of the other factors.The results of factorial experiments showed that Ta2O5 was mainly transformed into insoluble potassium tantalate at low temperature(350 ℃) and transformed into soluble potassium tantalate at high temperature(450 ℃).The insoluble potassium tantalate was analyzed by XRD,which was proved to be KTaO3.Differently,almost all Nb2O5 was transformed into soluble potassium niobate at 350-450℃.As for the mixture of Ta2O5 and Nb2O5,the dissolution rate of tantalum increased and the dissolution rate of niobium decreased as an interaction existed between niobium and tantalum.And increasing the mole ratio of Nb2O5 to Ta2O5 in the mixture was beneficial to the dissolution of both Ta2O5 and Nb2O5.In addition,the mechanism of the interaction between niobium and tantalum was also investigated through phase and chemical analysis.
基金financial support to this work from the Tribology Science Fund of the State Key Laboratory of Tribology(SKLT2020C09)National Natural Science Foundation of China(No.51675303)National Key Research and Development Program of China(2017YFB1103300)。
文摘Directed energy deposition has been used to repair superalloy components in aero engines and gas turbines.However,the microstructure and properties are generally inhomogeneous in components because of the different processing histories.Here,the microstructures and wear behavior of different zones(substrate,HAZ,and deposit)are investigated for the IC10 directionally solidified superalloy repaired by the directed energy deposition process.It is found that the microstructure of the deposited layers is strongly textured with a<001>-fiber texture in the building direction,and the texture intensity is continuously increased along the building direction.Two kinds ofγ’phase(primary and secondaryγ’phase)can be found in the heat-affected zone(HAZ),and the average size of primaryγ’phase is smaller than that in the substrate due to liquation.In the deposit layers,the size ofγ’phase is much smaller than those in the substrate and the primaryγ’phase of HAZ;both size and the fraction of theγ’phase decreases with the increase of building height.The wear rate of the substrate is the smallest,indicating the best wear resistance;while the wear rate of HAZ is the largest,indicating the worst wear resistance in the repaired sample.The wear rates in the deposit layers increase from the bottom to the top zones,showing a decreasing wear resistance.Abrasive wear is found to be the dominant wear mechanism of the repaired alloy,and the resistance to which is closely related to the fraction ofγ’phase in the microstructure.The understanding of the influence of microstructure on wear resistance allows for a more informed application of inhomogeneous superalloy components repaired by directed energy deposition in industry.
基金the National Natural Science Foundation of China(Grant No.50575171)the National Basic Research Program of China(Grant No.2007CB607604)the Open Financial Fund of the State Key Laboratory of Tribology of Tsinghua University(Grant No.SKLT05-02).
文摘An overview of the advances in studies on tribology of molecular deposition （MD） films is presented here to summarize the studies of nanofrictional properties, adhesion, wear and mechanical behavior, as well as the molecular dynamics simulation of nanotribological properties of the film in the last decade. Some key research topics which need to be investigate further are addressed.
基金This research was supported by Gold specialties Science Foundation of Finance Ministry （Grant Nos. 22800802039）；Yang Liqin, Niu Cuiyi and Zhao Yinyin are thanked for theirs participation in part of the work for this paper.
文摘The Hadamengou gold deposit is located in western part of the northern margin of the North China craton. It is a hydrothermal deposit related to alkaline magmatism. Dissolution of Au, Fe from pyrite and iron oxide （including magnetite and hematite） individual minerals in the three main types of ore shows： in iron oxides （magnetite and hematite）, Au and Fe were dissolved simultaneously and their solubilities are positively correlated, which means Au is mainly chemical-bonded （lattice gold） and/or colloidal-adsorbed in iron oxides; while in pyrite, on the contrary, Au dissolution obviously lags behind Fe and the solubility of Au shows negative relationship with that of Fe, which indicates Au is mainly hosted as grains of elemental gold （or native gold） within pyrite. Previous studies revealed that the Hadamengou gold deposit is characterized by intensive K-feldspathization and holds high content of iron oxides occasionally replaced by sulfides, which was caused by oxidizing K-enriched alkaline fluids under a stretching geodynamic setting. These geological features, together with the high Au-content in iron oxides, comparable with that of the Olympic Dam deposit in South Australia, suggest that this deposit is the first example of iron oxide-type gold deposits in China.
基金supported by the National Natural Science Foundation of China for Distinguished Young Scholars (No. 51825403)the National Natural Science Foundation of China (No. 51904355)the National Key R&D Program of China (No. 2020YFC1909201)。
文摘Lead(Pb) coprecipitation with jarosite is common in natural and engineered environments,such as acid mine drainage(AMD) sites and hydrometallurgical industry. Despite the high relevance for environmental impact, few studies have examined the exact interaction of Pb with jarosite and the dissolution behavior of each phase. In the present work, we demonstrate that Pb mainly interacts with jarosite in four modes, namely incorporation, occlusion,physically mixing, and chemically mixing. For comparison, the four modes of Pb-bearing natrojarosite were synthesized and characterized separately. Batch dissolution experiments were undertaken on these synthetic Pb-bearing natrojarosites under pH_(2) to simulate the AMD environments. The introduction of Pb decreases the final Fe releasing efficiency of jarosite-type compounds from 18.18% to 3.45%-5.01%, showing a remarkable inhibition of their dissolution. For Pb releasing behavior, PbSO_(4) dissolves in preference to Pb-substituted natrojarosite, i.e.,(Na, Pb)-jarosite, which primarily results in the sharp increase of Pb releasing concentration(> 40 mg/L). PbSO_(4) occlusion by jarosite-type compounds can significantly reduce the release of Pb. The results of this study could provide useful information regarding Fe and Pb cycling in acidic natural and engineered environments.
基金supported by National Natural Science Foundation of China(Grant No.50575135)Program for New Century Excellent Talents of Ministry of Education of China(Grant No.NCET-06-0399)Tribology Science Fund of the State Key Laboratory of Tribology,China
文摘The friction behavior of the hot filament chemical vapor deposition(HFCVD)diamond film plays a critical role on its applications in mechanical fields and largely depends on the environment.Studies on the tribological properties of HFCVD diamond films coated on Co-cemented tungsten carbide(WC-Co)substrates are rarely reported in available literatures,especially in the water lubricating conditions.In this paper,conventional microcrystalline diamond(MCD)and fine-grained diamond(FGD)films are deposited on WC-Co substrates and their friction properties are evaluated on a reciprocating ball-on-plate tribometer,where they are brought to slide against ball-bearing steel and copper balls in dry and water lubricating conditions.Scanning electron microscopy(SEM),atomic force microscopy(AFM),surface profilometer and Raman spectroscopy are adopted to characterize as-deposited diamond films;SEM and energy dispersive X-ray(EDX)are used to investigate the worn region on the surfaces of both counterface balls and diamond films.The research results show that the friction coefficient of HFCVD diamond films always starts with a high initial value,and then gradually transits to a relative stable state.For a given counterface and a sliding condition,the FGD film presents lower stable friction coefficients by 0.02-0.03 than MCD film.The transferred materials adhered on sliding interface are supposed to have predominate effect on the friction behaviors of HFCVD diamond films.Furthermore,the effect of water lubricating on reducing friction coefficient is significant.For a given counterpart,the stable friction coefficients of MCD or FGD films reduce by about 0.07-0.08 while sliding in the water lubricating condition,relative to in dry sliding condition.This study is beneficial for widespread applications of HFCVD diamond coated mechanical components and adopting water lubricating system,replacing ofoil lubricating,in a variety of mechanical processing fields to implement the green production process.
文摘In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it is feasible to dissolve gold in thiourea-alkaline medium. A thermodynamic study was conducted by chemical speciation using the method of Ro-jas-Hernández, together with an electrochemical study where the electric potential was swept in the anodic direction. The main results of the thermodynamic study were that formamidine disulfide (FDS) and sulfinic compounds (S.C.) prevail at alkaline pH;by increasing the initial concen-tration of thiourea at alkaline pH, the presence of the gold complex is al-most zero for any initial concentration of thiourea. By including sodium sulfite in the gold-thiourea system, it was possible to obtain the Au(I)-TU complex at alkaline pH, with a presence of 95.13%. Electrochemical tests allowed verifying that in the absence of sodium sulfite the dissolution of gold in an alkaline medium is very slow but adding sodium sulfite im-provements become evident in the dissolution of the metal. Therefore, sodium sulfite catalyzes the gold dissolution process and stabilizes the thiourea. With this study it was possible to establish the feasibility of using thiourea in an alkaline medium for the dissolution of gold, and the conditions under which it is possible to dissolve the gold in that medium. With these fundamentals and conditions, it is now possible to move forward to test this system for minerals and/or concentrates containing gold.
基金Project(2002AA420060) supported by the Hi-tech Research and Development Program of China
文摘Abstract: Based on the element life and death theory of finite element analysis(FEA), a three-dimensional multi-track and multi-layer model for laser metal deposition shaping(LMDS) was developed with ANSYS parametric design language(APDL), and detailed numerical simulations of temperature and thermal stress were conducted. Among those simulations, long-edge parallel reciprocating scanning method was introduced. The distribution regularities of temperature, temperature gradient, Von Mise’s effective stress, X-directional, Y-directional and Z-directional thermal stresses were studied. LMDS experiments were carried out with nickel-based superalloy using the same process parameters as those in simulation. The measured temperatures of molten pool are in accordance with the simulated results. The crack engendering and developing regularities of samples show good agreement with the simulation results.
文摘The properties orAl based nanocomposite metal foams and their corrosion behaviors were investigated in this study. For this, the composite metal foams with different relative densities （porosity） reinforced with alumina nanoparticles were prepared using a powder me- tallurgy-based sintering-dissolution process （SDP） and NaC1 particles were used as space holders. Then, the effect of nanoparticle rein- forcement and different amounts of NaC1 space holders （corresponding porosity） on the microstructure, morphology, density, hardness, and electrochemical specifications of the samples were investigated. It was found that as the relative density increased from 60% to 70%, the wall thickness increased from about 200 to 300 pro, which led to a decrease in pore size. Also, the addition of nanoparticle reinforcement and the increased relative density result in increasing metal foam hardness. Moreover, electrochemical test results indicated that increasing the A1203 content reduced the corrosion rate, but increasing the porosity enhanced it.
基金financially supported by the National Natural Science Foundation of China for Distinguished Young Scholar(No.52025042)the Open Fund of State Key Laboratory of Advanced Metallurgy(No.KF24-12)。
文摘This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential oxidation pathway of molybdenum into high-valence ions(Mo^(6+),Mo^(5+),Mo^(4+))under vary-ing electrolysis potentials.Electrochemical Impedance Spectroscopy(EIS)demonstrated that the dissolu-tion is governed by both charge transfer and diffusion mechanisms,with reduced impedance at higher potentials facilitating molybdenum dissolution.The reduction behavior of dissolved molybdenum ions was further explored using cyclic voltammetry(CV)and square wave voltammetry(SWV),confirming a multi-step reduction process controlled by diffusion and high reversibility.Nucleation studies using chronoamperometry established that molybdenum deposition follows an instantaneous nucleation mech-anism.Morphological analysis of cathodic deposits revealed that current density significantly influences particle size,transitioning from nano-sized spherical particles to larger equiaxed crystals with increasing current density.These findings provide a comprehensive understanding of molybdenum’s electrochemical properties in molten salts,offering valuable insights for optimizing electrolysis processes and advancing molybdenum-based material production.
