Rational developing high-performance and economically efficient dual-functional oxygen electrocatalysts to drive the lumberly reactivity rates of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)in Zn-a...Rational developing high-performance and economically efficient dual-functional oxygen electrocatalysts to drive the lumberly reactivity rates of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)in Zn-air batteries is highly attractive,yet remains conceptually challenging.Herein,Ni/MnO heterostructure nanosheets and nanoparticles firmly anchored onto the N-doped carbon nanofibers(noted as Ni/MnO@N-C NS/NFs)for efficient bifunctional ORR/OER electrocatalysis are designed and realized through a facile electrospinning-pyrolysis-etching strategy.The epitaxial in situ grown Ni/MnO with enriched oxygen vacancies stimulated the charge redistribution in their coupling regions,which effectively optimizes the adsorption/desorption of O-related intermediates in ORR/OER.Benefiting from the Ni/MnO heterostructure moieties and the unique two-dimensional/one-dimensional(2D/1D)superstructure of carbon support with abundantly dispersive active species,the resultant Ni/MnO@N-C NS/NFs deliver robust ORR activity and OER property(an overpotential of 306 mV to obtain 10 mA·cm^(-2))with a smaller potential gap(ΔE=0.77 V)in alkaline electrolyte.More significantly,practical zinc-air battery building with Ni/MnO@N-C NS/NFs delivers a higher open circuit voltage,excellent output power density,and prominent durability with stable charging and discharging cycle life.The present work demonstrates a crucial understanding of building advanced heterostructure electrocatalysts with enriched oxygen vacancies for metal-air batteries application.展开更多
The reactive materials filled structure(RMFS)is a structural penetrator that replaces high explosive(HE)with reactive materials,presenting a novel self-distributed initiation,multiple deflagrations behavior during pen...The reactive materials filled structure(RMFS)is a structural penetrator that replaces high explosive(HE)with reactive materials,presenting a novel self-distributed initiation,multiple deflagrations behavior during penetrating multi-layered plates,and generating a multipeak overpressure behind the plates.Here analytical models of RMFS self-distributed energy release and equivalent deflagration are developed.The multipeak overpressure formation model based on the single deflagration overpressure expression was promoted.The impact tests of RMFS on multi-layered plates at 584 m/s,616 m/s,and819 m/s were performed to validate the analytical model.Further,the influence of a single overpressure peak and time intervals versus impact velocity is discussed.The analysis results indicate that the deflagration happened within 20.68 mm behind the plate,the initial impact velocity and plate thickness are the crucial factors that dominate the self-distributed multipeak overpressure effect.Three formation patterns of multipeak overpressure are proposed.展开更多
Enhanced damage to the full-filled fuel tank,impacted by the cold pressed and sintered PTFE/Al/W reactive material projectile(RMP)with a density of 7.8 g/cm3,is investigated experimentally and theoretically.The fuel t...Enhanced damage to the full-filled fuel tank,impacted by the cold pressed and sintered PTFE/Al/W reactive material projectile(RMP)with a density of 7.8 g/cm3,is investigated experimentally and theoretically.The fuel tank is a rectangular structure,welded by six pieces of 2024 aluminum plate with a thickness of 6 mm,and filled with RP-3 aviation kerosene.Experimental results show that the kerosene is ignited by the RMP impact at a velocity above 1062 m/s,and a novel interior ignition phenomenon which is closely related to the rupture effect of the fuel tank is observed.However,the traditional steel projectile with the same mass and dimension requires a velocity up to 1649 m/s to ignite the kerosene.Based on the experimental results,the radial pressure field is considered to be the main reason for the shear failure of weld.For mechanism considerations,the chemical energy released by the RMP enhances the hydrodynamic ram(HRAM)effect and provides additional ignition sources inside the fuel tank,thereby enhancing both rupture and ignition effects.Moreover,to further understand the enhanced ignition effect of RMP,the reactive debris temperature inside the kerosene is analyzed theoretically.The initiated reactive debris with high temperature provides effective interior ignition sources to ignite the kerosene,resulting in the enhanced ignition of the kerosene.展开更多
In this research,the effect of the sintering and cooling process on geometry distortion and mechanical properties of PTFE/Al reactive material is investigated.Six particularly selected sintering temperatures,three dif...In this research,the effect of the sintering and cooling process on geometry distortion and mechanical properties of PTFE/Al reactive material is investigated.Six particularly selected sintering temperatures,three different cooling modes(annealing cooling,normalizing cooling and rapid cooling),three different initial cooling temperature s,as well as six different final cooling temperatures were designed to compare the effects of sintering temperature,cooling rate,initial cooling temperature and final cooling temperature on the properties of reactive materials.Geometry distortion was quantitatively analyzed by a statistic on the dimensional changes of the specimens and microscopic morphology.A mechanical response properties transition from brittle to ductile was found and analyzed.By combining the thermodynamic properties of PTFE and unsteady heat conduction theory,mechanisms of cooling induced morphology change,temperature induced distortion and strength decrease were obtained.The results showed that the cooling rate has the most significant effect on the morphology transformation,while initial cooling temperature has more significant effect on the dimensional distortion than final cooling temperature.As to the mechanical properties transition from brittle to plastic,a more prominent effect of initial cooling temperature than cooling rate and final temperature was revealed.展开更多
Penetration and internal blast behavior of reactive liner enhanced shaped charge against concrete space were investigated through experiments and simulations.The volume of the enclosed concrete space is about 15 m^(3)...Penetration and internal blast behavior of reactive liner enhanced shaped charge against concrete space were investigated through experiments and simulations.The volume of the enclosed concrete space is about 15 m^(3).The reactive liner enhanced shaped charge utilizes reactive copper double-layered liner,which is composed of an inner copper liner and an outer reactive liner,while the reactive material liner is fabricated by PTFE/Al(Polytetrafluoroethylene/Aluminum)powders through cold-pressing and sintering.Static explosion experiments show that,compared with the shaped charge which utilizes copper liner,the penetration cavity diameter and spalling area of concrete by the novel shaped charge were enlarged to 2 times and 4 times,respectively.Meanwhile,the following reactive material had blast effect and produced significant overpressure inside the concrete closed space.Theoretical analysis indicates concrete strength and detonation pressure of reactive material both affect the penetration cavity diameter.To the blast behavior of reactive material inside the concrete space,developing TNT equivalence model and simulated on AUTODYN-3 D for analysis.Simulation results reproduced propagation process of the shock wave in concrete space,and revealed multi-peaks phenomenon of overpressure-time curves.Furthermore,the empirical relationship between the peak overpressure and relative distance for the shock wave of reactive material was proposed.展开更多
In this paper, the reaction characteristic and its application in shaped charge warhead of a novel reactive material, which introduced copper(Cu) and plumbum(Pb) into traditional polytetrafluoroethylene/aluminum(PTFE/...In this paper, the reaction characteristic and its application in shaped charge warhead of a novel reactive material, which introduced copper(Cu) and plumbum(Pb) into traditional polytetrafluoroethylene/aluminum(PTFE/Al), are studied. The thermal analysis and chemical reaction behavior of the PTFE/Al/Cu/Pb mixture are investigated by Differential Scanning Calorimetry(DSC),Thermo-gravimetry(TG), and Xray Diffraction(XRD) techniques. Then, the shaped charge liners with PTFE/Al/Cu/Pb reactive materials are fabricated, and the X-ray experiments show that they could form reactive jets with excellent performance under the detonation effects of the shaped charge. Based on that, the penetration experiments of shaped charge with PTFE/Al/Cu/Pb reactive liner against steel plates are carried out, and the results demonstrate that the PTFE/Al/Cu/Pb reactive jets could produce a deeper penetration depth compared to the traditional PTFE/Al reactive jets. Meanwhile, the PTFE/Al/Cu/Pb reactive jets also show significant inner-blast effects, leading to dramatically cracking or fragmentation behavior of the penetrated steel plates. This new PTFE/Al/Cu/Pb reactive liner shaped charge presents enhanced penetration behavior for steel targets that incorporates the penetration capability of a high-density and ductility jet, and the chemical energy release of PTFE-matrix reactive materials.展开更多
Formation behaviors of rod-like reactive shaped charge penetrator(RRSCP)and their effects on damage capability are investigated by experiments and numerical simulations.The pulsed X-ray technology and a spaced aluminu...Formation behaviors of rod-like reactive shaped charge penetrator(RRSCP)and their effects on damage capability are investigated by experiments and numerical simulations.The pulsed X-ray technology and a spaced aluminum/steel plate with the thicknesses of 5 mm/100 mm are used.Three types of sphericalsegment aluminum-polytetrafluoroethylene-copper(Al-PTFE-Cu)reactive liners with Cu contents of 0%,46.6%,and 66%are fabricated and tested.The experimental results show that the reactive liners can form excellent rod-shaped penetrators with tail skirts under the shaped charge effect,but the tail skirts disappear over time.Moreover,rupturing damage to the aluminum plate and penetration to the steel plate are caused by the RRSCP impact.From simulation analysis,the RRSCP is formed by a mechanically and chemically coupled response with the reactive liner activated by shock in its outer walls and bottom and then backward overturning,forming a leading reactive penetrator and a following chemical energy cluster.The unique formation structure determines the damage modes of the aluminum plate and the steel plate.Further analysis indicates that the formation behaviors and damage capability of Al-PTFE-Cu RRSCP strongly depend on Cu content.With increasing Cu content,the velocity,activation extent,and reaction extent of Al-PTFE-Cu RRSCP decrease,which contribute to elongation and alleviate the negative effects of chemical reactions on elongation,significantly increasing the length-diameter ratio and thus enhancing the capability of steel plate penetration.However,the lower activation extent and energetic density will weaken the RRSCP's capability of causing rupturing damage to the aluminum plate.展开更多
Combining the methods of theoretical,numerical and experimental,this research focuses on the jet formation behavior and optimization of trunconical hypercumulation shaped charge structure.With the three-stage division...Combining the methods of theoretical,numerical and experimental,this research focuses on the jet formation behavior and optimization of trunconical hypercumulation shaped charge structure.With the three-stage division,formation theory of trunconical hypercumulation shaped charge jet is established based on micro element method.By dimensional analysis,main control parameters are identified and their effect on jet formation are analyzed.Through numerical modelling and orthogonal optimization method,influence of the factors and their levels over the indicators of jet tip velocity and jet length as well as order of the significance of each factor and level are obtained.Penetration experiments of trunconical hypercumulation shaped charge based on the orthogonal optimization reveals its advantage over traditional conical shaped charge structure,and finally determines the optimal influence factor level combination.The research and results would provide useful guide for the design and application of trunconical hypercumulation shaped charge structure.展开更多
Compared with PELE with inert fillings such as polyethylene and nylon,reactive PELE(RPELE)shows excellent damage effects when impacting concrete targets due to the filling deflagration reaction.In present work,an anal...Compared with PELE with inert fillings such as polyethylene and nylon,reactive PELE(RPELE)shows excellent damage effects when impacting concrete targets due to the filling deflagration reaction.In present work,an analytical model describing the jacket deformation and concrete target damage impacted by RPELE was presented,in which the radial rarefaction and filling deflagration reaction were considered.The impact tests of RPELE on concrete target in the 592-1012 m/s were carried out to verify the analytical model.Based on the analytical model,the angle-length evolution mechanism of the jacket bending-curling deformation was revealed,and the concrete target damage was further analyzed.One can find out that the average prediction errors of the front crater,opening and back crater are 6.8%,8.5%and 7.1%,respectively.Moreover,the effects of radial rarefaction and deflagration were discussed.It was found that the neglect of radial rarefaction overestimates the jacket deformation and concrete target damage,while the deflagration reaction of filling increases the diameter of the front crater,opening and back crater by 25.4%,24.3%and 31.1%,respectively.The research provides a valuable reference for understanding and predicting the jacket deformation and concrete target damage impacted by RPELE.展开更多
Zirconium,titanium,and other hexagonally close-packed(HCP)metals and their alloys are representative high specific strength,high reaction enthalpy,and high thermal conductivity structural materials.In this study,two t...Zirconium,titanium,and other hexagonally close-packed(HCP)metals and their alloys are representative high specific strength,high reaction enthalpy,and high thermal conductivity structural materials.In this study,two typical HCP metals,zirconium,and titanium,were applied to reactive materials(RMs)to prepare Zr/PTFE/W RMs and Ti/PTFE/W RMs,validating the feasibility of HCP metal/PTFE/W RMs.The impact response process of typical HCP metal/PTFE/W RMs under high-velocity dynamic loads was studied using shock equations of state(EOS)based on porous mixtures and chemical reaction kinetics equations.An improved hemispherical quasi-sealed test chamber was employed to measure the energy release characteristic curves of 10 types of Zr/PTFE/W RMs and Ti/PTFE/W RMs under impact velocities ranging from 500 m/s to 1300 m/s.The datasets of the impact-induced energy release characteristics of HCP metal/PTFE/W RMs were established.Additionally,the energy release efficiency of HCP metal/PTFE/W RMs under impact was predicted using the support vector regression(SVR)kernel function model.The datasets of Zr/PTFE/W RMs and Ti/PTFE/W RMs with W contents of 0%,25%,50%,and 75%were used as test sets,respectively.The model predictions showed a high degree of agreement with the experimental data,with mean absolute errors(MAE)of 4.8,6.5,4.6,and 4.1,respectively.展开更多
Wave shaper effect on formation behavior and penetration performance of reactive liner shaped charge(RLSC)are investigated by experiments and simulations.The reactive materials liner with a density of2.3 g/cm^3 is fab...Wave shaper effect on formation behavior and penetration performance of reactive liner shaped charge(RLSC)are investigated by experiments and simulations.The reactive materials liner with a density of2.3 g/cm^3 is fabricated by cold pressing at a pressure of 300 MPa and sintering at a temperature of 380℃.Experiments of the RLSC with and without wave shaper against steel plates are carried out at standoffs of0.5,1.0,and 1.5 CD(charge diameter),respectively.The experimental results show that the penetration depths and structural damage effects of steel plates decrease with increasing the standoff,while the penetration depths and the damage effects of RLSC without wave shaper are much greater than that with wave shaper at the same standoff.To understand the unusual experimental results,numerical simulations based on AUTODYN-2 D code are conducted to discuss the wave shaper effect,including the propagation behavior of detonation wave,the velocity and temperature distribution of reactive jet,and penetration depth of reactive jet.The simulations indicate that,compared with RLSC without wave shaper,there is a higher temperature produced inside reactive jet with wave shaper.This unusual temperature rise effects are likely to be an important mechanism to cause the initiation delay time of reactive jet to decline,which results in significantly decreasing its penetration performance.展开更多
Reactive material projectiles can be an extremely efficient lethality enhancement technology that incorporates the defeat mechanisms of chemical energy and kinetic energy.This paper presents such a research on the enh...Reactive material projectiles can be an extremely efficient lethality enhancement technology that incorporates the defeat mechanisms of chemical energy and kinetic energy.This paper presents such a research on the enhanced ignition behavior of reactive material projectiles impacting a fuel-filled tank.Firstly,the ignition process description of the fuel-filled tank impacted by inert metal and reactive material projectiles is presented.Secondly,ballistic impact experiments are performed to investigate the ignition effects of the fuel-filled tank impacted by reactive material versus tungsten alloy projectiles with mass matched.The fuel tank used for the experiments is a cylindrical steel casing structure filled with aviation kerosene and sealed with aluminum cover plates on both ends using screw bolts.The experimental results indicate that,compared with impacts from tungsten alloy projectiles,there is dramatically enhanced structural damage to the fuel-filled tank and an enhanced ignition effect caused by reactive material projectile impacts.Finally,an analytical model is developed,by which the effects of the aluminum cover plate thickness on critical structural failure energy of the fuel-filled tank and the total energy of the reactive material projectile deposited into the fuel-filled tank are discussed.The analysis shows a good agreement with the experiments.展开更多
In this paper, a bionic method was presented to improve the erosion resistance of blade of the centrifugal fan. A numerical investigation of the solid particle erosion on the standard and bionic configuration blade of...In this paper, a bionic method was presented to improve the erosion resistance of blade of the centrifugal fan. A numerical investigation of the solid particle erosion on the standard and bionic configuration blade of 4-72N_o10C centrifugal fan was presented. The numerical study employs computational fluid dynamics （CFD） software, based on a finite volume method, in which the discrete phase model was used to modele the solid particles flow, and the Eulerian conservation equation was adopt to simulate the continuous phase. Moreover, user-defined function was used to define wear equation. The various diameters of the particles were taken into account. The positions of collision of standard and bionic fan blades were discussed, and two kinds of centrifugal fan blade wear were compared. The results show that the particles from the incident source with different positions have different processes of turning and movement when enter into the impeller. The trajectories of flow in the fan channel are significantly different for the particles with different diameters. Bionic fan blade have lower erosion rate than the standard fan blade when the particle size is 20 μm. The anti-erosion mechanism of the bionic fan blade was discussed.展开更多
The formation and separation behaviors of tandem EFPs are studied by the combination of experiments and simulations.The results show that different formation and separation processes can be obtained by adjusting the d...The formation and separation behaviors of tandem EFPs are studied by the combination of experiments and simulations.The results show that different formation and separation processes can be obtained by adjusting the double-layer liners,and simulations agree with experiments well.Then,the interaction process between the two liners is discussed in details,and the formation and separation mechanism are revealed.It can be found that there are four phases in the formation and separation processes,including impact phase,propulsion phase,slide phase and free flight phase.During the impact phase,the velocities of two liners rise in turns with kinetic energy exchange.In the propulsion phase,the axial impact becomes insignificant,but the radial interaction between two liners influences the appearance of tandem EFPs.Meanwhile,it should be mentioned that the inner surface of foregoing EFP remains to be in contact with the outer surface of following EFP in the propulsion phase,and the following one would continue to push the foregoing one for about 10μ to 20 μs,causing the velocities of following and foregoing EFPs gradually decreasing and increasing respectively.In the slide phase,an obvious relative movement occurs between the two EFPs,and there would be barely kinetic energy exchange.Then,the two EFPs separate gradually and get into the phase of free flight.Generally,if the outer and inner liners have the same thickness,the outer copper-inner copper liners form two long EFPs,the outer copper-inner steel liners become a foregoing short steel EFP and a following long copper EFP,and the outer steel-inner copper liners produce a foregoing long copper EFP and a following conical steel EFP.In addition,thickness match also has an important impact on formation appearance and separation process for both outer copperinner copper liners and outer steel-inner copper liners.With the thickness ratio of outer liner to inner liner decreasing,the length and length-diameter ratio of both foregoing and following EFPs increase gradually.展开更多
In this paper,the ballistic impact experiments,including impact test chamber and impact double-spaced plates,were conducted to study the reaction behaviors of a novel functionally graded reactive material(FGRM),which ...In this paper,the ballistic impact experiments,including impact test chamber and impact double-spaced plates,were conducted to study the reaction behaviors of a novel functionally graded reactive material(FGRM),which was composed of polytetrafluoroethylene/aluminum(PTFE/Al)and PTFE/Al/bismuth trioxide(Bi_(2)O_(3)).The experiments showed that the impact direction of the FGRM had a significant effect on the reaction.With the same impact velocity,when the first impact material was PTFE/Al/Bi_(2)O_(3),compared with first impact material PTFE/Al,the FGRM induced higher overpressure in the test chamber and larger damaged area of double-spaced plates.The theoretical model,which considered the shock wave generation and propagation,the effect of the shock wave on reaction efficiency,and penetration behaviors,was developed to analyze the reaction behaviors of the FGRM.The model predicted first impact material of the FGRM with a higher shock impedance was conducive to the reaction of reactive materials.The conclusion of this study provides significant information about the design and application of reactive materials.展开更多
Force chains based mesoscale simulation is conducted to investigate the response behavior of aluminumpolytetrafluoroethylene(Al-PTFE)granular composites under a low-velocity impact.A two-dimensional model followed the...Force chains based mesoscale simulation is conducted to investigate the response behavior of aluminumpolytetrafluoroethylene(Al-PTFE)granular composites under a low-velocity impact.A two-dimensional model followed the randomly normal distribution of real Al particles size is developed.The dynamic compressive process of Al-PTFE composites with varied Al mass fraction is simulated and validated against the experiments.The results indicate that,force chains behavior governed by the number and the size of agglomerated Al particles,significantly affects the impact response of the material.The failure mode of the material evolves from shear failure of matrix to debonding failure of particles with increasing density.A high crack area of the material is critical mechanism to arouse the initiation reaction.The damage maintained by force chains during large plastic strain builds up more local stresses concentration to enhance a possible reaction performance.In addition,simulation is performed with identical mass fraction but various Al size distribution to explore the effects of size centralization and dispersion on the mechanical properties of materials.It is found that smaller sized Al particle of composites are more preferred than its bulky material in ultimate strength.Increasing dispersed degree is facilitated to create stable force chains in samples with comparable particle number.The simulation studies provide further insights into the plastic deformation,failure mechanism,and possible energy release capacity for Al-PTFE composites,which is helpful for further design and application of reactive materials.展开更多
In this study,waste cotton fabric was used as cellulose raw material and pretreated in aqueous NaOH/urea solution system to investigate the effect of NaOH/urea pretreatment solution on the hydrolysis of cotton fiber.T...In this study,waste cotton fabric was used as cellulose raw material and pretreated in aqueous NaOH/urea solution system to investigate the effect of NaOH/urea pretreatment solution on the hydrolysis of cotton fiber.The cotton fiber was pretreated with different conditions of aqueous NaOH/urea solution,and the pretreated cotton fiber was hydrolyzed under the same conditions as the original cotton fiber.The results of characterization analysis showed that water retention value of pretreated cotton fiber was higher than that of unpretreated sample.Moreover,the cotton fiber presented both a convoluted structure and a coarser surface,XRD results suggested that the crystallinity degree of cellulose decreased dramatically,more cellulose II appeared,and the hydrogen bond is broken.Among the different pretreatment conditions,the pretreatment effect was the best when the reaction temperature was 0°C,the solid-liquid ratio was 2:50,and the NaOH/urea ratio was 7:12.The hydrolysis experiments of pretreated and unpretreated cotton fibers showed that when the hydrothermal temperature was 230°C,the heat preservation was 2 h,and the hydrochloric acid concentration was 5 wt.%,the glucose yield reached 29.99%.H+could catalyze the hydrolysis of cotton fiber more effectively due to damage to crystal structure and hydrogen bonds.展开更多
To investigate the thermal response and initiation behavior of ternary fluoropolymer-matrix PTFE/Al/W reactive materials,a research combining shock loading tests and trans-scale modelling is conducted.On the basis of ...To investigate the thermal response and initiation behavior of ternary fluoropolymer-matrix PTFE/Al/W reactive materials,a research combining shock loading tests and trans-scale modelling is conducted.On the basis of a good agreement of the numerically simulated and tested shock wave propagation,the significant impact of component ratios and particle sizes on the evolution of mesoscopic temperature,hot-spots and initiation is well characterized and analyzed.Results demonstrate that as the content of W increases,the range of mesoscopic high-temperature area increases and tends to distribute more uniform,while material with smaller W particles causes more intense particle deformation and larger temperature rise.The time to reach the critical temperature shows positive correlation to the content of W,while the critical temperature of hot-spots shows negative correlation to the particle size of W.For PTFE/Al/W of high density,with the increase of W particle size,the reaction rate decrease,however the time to reach the peak reaction rate shortens.展开更多
基金supported by the National Natural Science Foundation of China(No.22302096)the Natural Science Foundation of Jiangsu Higher Education Institutions of China(Nos.23KJB150039 and 24KJB150026)+1 种基金Natural Science Foundation of Zhejiang Province(No.LQ24E040002)the Natural Science Foundation of Huzhou City(No.2023YZ18).
文摘Rational developing high-performance and economically efficient dual-functional oxygen electrocatalysts to drive the lumberly reactivity rates of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)in Zn-air batteries is highly attractive,yet remains conceptually challenging.Herein,Ni/MnO heterostructure nanosheets and nanoparticles firmly anchored onto the N-doped carbon nanofibers(noted as Ni/MnO@N-C NS/NFs)for efficient bifunctional ORR/OER electrocatalysis are designed and realized through a facile electrospinning-pyrolysis-etching strategy.The epitaxial in situ grown Ni/MnO with enriched oxygen vacancies stimulated the charge redistribution in their coupling regions,which effectively optimizes the adsorption/desorption of O-related intermediates in ORR/OER.Benefiting from the Ni/MnO heterostructure moieties and the unique two-dimensional/one-dimensional(2D/1D)superstructure of carbon support with abundantly dispersive active species,the resultant Ni/MnO@N-C NS/NFs deliver robust ORR activity and OER property(an overpotential of 306 mV to obtain 10 mA·cm^(-2))with a smaller potential gap(ΔE=0.77 V)in alkaline electrolyte.More significantly,practical zinc-air battery building with Ni/MnO@N-C NS/NFs delivers a higher open circuit voltage,excellent output power density,and prominent durability with stable charging and discharging cycle life.The present work demonstrates a crucial understanding of building advanced heterostructure electrocatalysts with enriched oxygen vacancies for metal-air batteries application.
基金the support received from the National Natural Science Foundation of China(Grant No.12302460)the State Key Laboratory of Explosion Science and Safety Protection(Grant No.YBKT24-02)。
文摘The reactive materials filled structure(RMFS)is a structural penetrator that replaces high explosive(HE)with reactive materials,presenting a novel self-distributed initiation,multiple deflagrations behavior during penetrating multi-layered plates,and generating a multipeak overpressure behind the plates.Here analytical models of RMFS self-distributed energy release and equivalent deflagration are developed.The multipeak overpressure formation model based on the single deflagration overpressure expression was promoted.The impact tests of RMFS on multi-layered plates at 584 m/s,616 m/s,and819 m/s were performed to validate the analytical model.Further,the influence of a single overpressure peak and time intervals versus impact velocity is discussed.The analysis results indicate that the deflagration happened within 20.68 mm behind the plate,the initial impact velocity and plate thickness are the crucial factors that dominate the self-distributed multipeak overpressure effect.Three formation patterns of multipeak overpressure are proposed.
文摘Enhanced damage to the full-filled fuel tank,impacted by the cold pressed and sintered PTFE/Al/W reactive material projectile(RMP)with a density of 7.8 g/cm3,is investigated experimentally and theoretically.The fuel tank is a rectangular structure,welded by six pieces of 2024 aluminum plate with a thickness of 6 mm,and filled with RP-3 aviation kerosene.Experimental results show that the kerosene is ignited by the RMP impact at a velocity above 1062 m/s,and a novel interior ignition phenomenon which is closely related to the rupture effect of the fuel tank is observed.However,the traditional steel projectile with the same mass and dimension requires a velocity up to 1649 m/s to ignite the kerosene.Based on the experimental results,the radial pressure field is considered to be the main reason for the shear failure of weld.For mechanism considerations,the chemical energy released by the RMP enhances the hydrodynamic ram(HRAM)effect and provides additional ignition sources inside the fuel tank,thereby enhancing both rupture and ignition effects.Moreover,to further understand the enhanced ignition effect of RMP,the reactive debris temperature inside the kerosene is analyzed theoretically.The initiated reactive debris with high temperature provides effective interior ignition sources to ignite the kerosene,resulting in the enhanced ignition of the kerosene.
基金The authors are very grateful for the support received from the National Natural Science Foundation of China(No.11202030)State Key Laboratory of the State Key Laboratory of Explosion Science and Technology(QNKT19-03).
文摘In this research,the effect of the sintering and cooling process on geometry distortion and mechanical properties of PTFE/Al reactive material is investigated.Six particularly selected sintering temperatures,three different cooling modes(annealing cooling,normalizing cooling and rapid cooling),three different initial cooling temperature s,as well as six different final cooling temperatures were designed to compare the effects of sintering temperature,cooling rate,initial cooling temperature and final cooling temperature on the properties of reactive materials.Geometry distortion was quantitatively analyzed by a statistic on the dimensional changes of the specimens and microscopic morphology.A mechanical response properties transition from brittle to ductile was found and analyzed.By combining the thermodynamic properties of PTFE and unsteady heat conduction theory,mechanisms of cooling induced morphology change,temperature induced distortion and strength decrease were obtained.The results showed that the cooling rate has the most significant effect on the morphology transformation,while initial cooling temperature has more significant effect on the dimensional distortion than final cooling temperature.As to the mechanical properties transition from brittle to plastic,a more prominent effect of initial cooling temperature than cooling rate and final temperature was revealed.
基金supported by National Natural Science Foundation of china[grant number:U1730112]。
文摘Penetration and internal blast behavior of reactive liner enhanced shaped charge against concrete space were investigated through experiments and simulations.The volume of the enclosed concrete space is about 15 m^(3).The reactive liner enhanced shaped charge utilizes reactive copper double-layered liner,which is composed of an inner copper liner and an outer reactive liner,while the reactive material liner is fabricated by PTFE/Al(Polytetrafluoroethylene/Aluminum)powders through cold-pressing and sintering.Static explosion experiments show that,compared with the shaped charge which utilizes copper liner,the penetration cavity diameter and spalling area of concrete by the novel shaped charge were enlarged to 2 times and 4 times,respectively.Meanwhile,the following reactive material had blast effect and produced significant overpressure inside the concrete closed space.Theoretical analysis indicates concrete strength and detonation pressure of reactive material both affect the penetration cavity diameter.To the blast behavior of reactive material inside the concrete space,developing TNT equivalence model and simulated on AUTODYN-3 D for analysis.Simulation results reproduced propagation process of the shock wave in concrete space,and revealed multi-peaks phenomenon of overpressure-time curves.Furthermore,the empirical relationship between the peak overpressure and relative distance for the shock wave of reactive material was proposed.
基金funded under the National Natural Science Foundation of China (No. 12002046)the study was also supported by the State Key Laboratory of Explosion Science and Technology of China。
文摘In this paper, the reaction characteristic and its application in shaped charge warhead of a novel reactive material, which introduced copper(Cu) and plumbum(Pb) into traditional polytetrafluoroethylene/aluminum(PTFE/Al), are studied. The thermal analysis and chemical reaction behavior of the PTFE/Al/Cu/Pb mixture are investigated by Differential Scanning Calorimetry(DSC),Thermo-gravimetry(TG), and Xray Diffraction(XRD) techniques. Then, the shaped charge liners with PTFE/Al/Cu/Pb reactive materials are fabricated, and the X-ray experiments show that they could form reactive jets with excellent performance under the detonation effects of the shaped charge. Based on that, the penetration experiments of shaped charge with PTFE/Al/Cu/Pb reactive liner against steel plates are carried out, and the results demonstrate that the PTFE/Al/Cu/Pb reactive jets could produce a deeper penetration depth compared to the traditional PTFE/Al reactive jets. Meanwhile, the PTFE/Al/Cu/Pb reactive jets also show significant inner-blast effects, leading to dramatically cracking or fragmentation behavior of the penetrated steel plates. This new PTFE/Al/Cu/Pb reactive liner shaped charge presents enhanced penetration behavior for steel targets that incorporates the penetration capability of a high-density and ductility jet, and the chemical energy release of PTFE-matrix reactive materials.
基金the National Natural Science Foundation of China(No.12172052 and No.12132003).
文摘Formation behaviors of rod-like reactive shaped charge penetrator(RRSCP)and their effects on damage capability are investigated by experiments and numerical simulations.The pulsed X-ray technology and a spaced aluminum/steel plate with the thicknesses of 5 mm/100 mm are used.Three types of sphericalsegment aluminum-polytetrafluoroethylene-copper(Al-PTFE-Cu)reactive liners with Cu contents of 0%,46.6%,and 66%are fabricated and tested.The experimental results show that the reactive liners can form excellent rod-shaped penetrators with tail skirts under the shaped charge effect,but the tail skirts disappear over time.Moreover,rupturing damage to the aluminum plate and penetration to the steel plate are caused by the RRSCP impact.From simulation analysis,the RRSCP is formed by a mechanically and chemically coupled response with the reactive liner activated by shock in its outer walls and bottom and then backward overturning,forming a leading reactive penetrator and a following chemical energy cluster.The unique formation structure determines the damage modes of the aluminum plate and the steel plate.Further analysis indicates that the formation behaviors and damage capability of Al-PTFE-Cu RRSCP strongly depend on Cu content.With increasing Cu content,the velocity,activation extent,and reaction extent of Al-PTFE-Cu RRSCP decrease,which contribute to elongation and alleviate the negative effects of chemical reactions on elongation,significantly increasing the length-diameter ratio and thus enhancing the capability of steel plate penetration.However,the lower activation extent and energetic density will weaken the RRSCP's capability of causing rupturing damage to the aluminum plate.
基金support from the Beijing Municipal Natural Science Foundation(Grant No.1214022).
文摘Combining the methods of theoretical,numerical and experimental,this research focuses on the jet formation behavior and optimization of trunconical hypercumulation shaped charge structure.With the three-stage division,formation theory of trunconical hypercumulation shaped charge jet is established based on micro element method.By dimensional analysis,main control parameters are identified and their effect on jet formation are analyzed.Through numerical modelling and orthogonal optimization method,influence of the factors and their levels over the indicators of jet tip velocity and jet length as well as order of the significance of each factor and level are obtained.Penetration experiments of trunconical hypercumulation shaped charge based on the orthogonal optimization reveals its advantage over traditional conical shaped charge structure,and finally determines the optimal influence factor level combination.The research and results would provide useful guide for the design and application of trunconical hypercumulation shaped charge structure.
基金funding from the National Natural Science Foundation of China(Grant Nos.12132003 and 12302460)。
文摘Compared with PELE with inert fillings such as polyethylene and nylon,reactive PELE(RPELE)shows excellent damage effects when impacting concrete targets due to the filling deflagration reaction.In present work,an analytical model describing the jacket deformation and concrete target damage impacted by RPELE was presented,in which the radial rarefaction and filling deflagration reaction were considered.The impact tests of RPELE on concrete target in the 592-1012 m/s were carried out to verify the analytical model.Based on the analytical model,the angle-length evolution mechanism of the jacket bending-curling deformation was revealed,and the concrete target damage was further analyzed.One can find out that the average prediction errors of the front crater,opening and back crater are 6.8%,8.5%and 7.1%,respectively.Moreover,the effects of radial rarefaction and deflagration were discussed.It was found that the neglect of radial rarefaction overestimates the jacket deformation and concrete target damage,while the deflagration reaction of filling increases the diameter of the front crater,opening and back crater by 25.4%,24.3%and 31.1%,respectively.The research provides a valuable reference for understanding and predicting the jacket deformation and concrete target damage impacted by RPELE.
基金sponsored by the National Natural Science Foundation of China(Grant Nos.U2241285,62201267)。
文摘Zirconium,titanium,and other hexagonally close-packed(HCP)metals and their alloys are representative high specific strength,high reaction enthalpy,and high thermal conductivity structural materials.In this study,two typical HCP metals,zirconium,and titanium,were applied to reactive materials(RMs)to prepare Zr/PTFE/W RMs and Ti/PTFE/W RMs,validating the feasibility of HCP metal/PTFE/W RMs.The impact response process of typical HCP metal/PTFE/W RMs under high-velocity dynamic loads was studied using shock equations of state(EOS)based on porous mixtures and chemical reaction kinetics equations.An improved hemispherical quasi-sealed test chamber was employed to measure the energy release characteristic curves of 10 types of Zr/PTFE/W RMs and Ti/PTFE/W RMs under impact velocities ranging from 500 m/s to 1300 m/s.The datasets of the impact-induced energy release characteristics of HCP metal/PTFE/W RMs were established.Additionally,the energy release efficiency of HCP metal/PTFE/W RMs under impact was predicted using the support vector regression(SVR)kernel function model.The datasets of Zr/PTFE/W RMs and Ti/PTFE/W RMs with W contents of 0%,25%,50%,and 75%were used as test sets,respectively.The model predictions showed a high degree of agreement with the experimental data,with mean absolute errors(MAE)of 4.8,6.5,4.6,and 4.1,respectively.
基金funded under the National Natural Science Foundation of China (No. U1730112)supported by the State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology
文摘Wave shaper effect on formation behavior and penetration performance of reactive liner shaped charge(RLSC)are investigated by experiments and simulations.The reactive materials liner with a density of2.3 g/cm^3 is fabricated by cold pressing at a pressure of 300 MPa and sintering at a temperature of 380℃.Experiments of the RLSC with and without wave shaper against steel plates are carried out at standoffs of0.5,1.0,and 1.5 CD(charge diameter),respectively.The experimental results show that the penetration depths and structural damage effects of steel plates decrease with increasing the standoff,while the penetration depths and the damage effects of RLSC without wave shaper are much greater than that with wave shaper at the same standoff.To understand the unusual experimental results,numerical simulations based on AUTODYN-2 D code are conducted to discuss the wave shaper effect,including the propagation behavior of detonation wave,the velocity and temperature distribution of reactive jet,and penetration depth of reactive jet.The simulations indicate that,compared with RLSC without wave shaper,there is a higher temperature produced inside reactive jet with wave shaper.This unusual temperature rise effects are likely to be an important mechanism to cause the initiation delay time of reactive jet to decline,which results in significantly decreasing its penetration performance.
基金funded under the National Innovation and Exploration Research Programsupported by the State Key Laboratory of Explosion Science and Technology Foundation of China
文摘Reactive material projectiles can be an extremely efficient lethality enhancement technology that incorporates the defeat mechanisms of chemical energy and kinetic energy.This paper presents such a research on the enhanced ignition behavior of reactive material projectiles impacting a fuel-filled tank.Firstly,the ignition process description of the fuel-filled tank impacted by inert metal and reactive material projectiles is presented.Secondly,ballistic impact experiments are performed to investigate the ignition effects of the fuel-filled tank impacted by reactive material versus tungsten alloy projectiles with mass matched.The fuel tank used for the experiments is a cylindrical steel casing structure filled with aviation kerosene and sealed with aluminum cover plates on both ends using screw bolts.The experimental results indicate that,compared with impacts from tungsten alloy projectiles,there is dramatically enhanced structural damage to the fuel-filled tank and an enhanced ignition effect caused by reactive material projectile impacts.Finally,an analytical model is developed,by which the effects of the aluminum cover plate thickness on critical structural failure energy of the fuel-filled tank and the total energy of the reactive material projectile deposited into the fuel-filled tank are discussed.The analysis shows a good agreement with the experiments.
基金supported by National Natural Science Foundation of China (Nos. 51175220 and 51205161)Specialized Research Fund for the Doctoral Program of Higher Education (No. 20100061110023)+3 种基金the Projects of Cooperation and Innovation to National Potential Oil and Gas for Production and Research (No. OSR-04-04)China Postdoctoral Science Foundation (No. 2012M511345)Ten Outstanding Youth Fund Project of Jilin University(No. 200905016)Basic Scientific Research Expenses of Project of Jilin University (No. 450060481176)
文摘In this paper, a bionic method was presented to improve the erosion resistance of blade of the centrifugal fan. A numerical investigation of the solid particle erosion on the standard and bionic configuration blade of 4-72N_o10C centrifugal fan was presented. The numerical study employs computational fluid dynamics （CFD） software, based on a finite volume method, in which the discrete phase model was used to modele the solid particles flow, and the Eulerian conservation equation was adopt to simulate the continuous phase. Moreover, user-defined function was used to define wear equation. The various diameters of the particles were taken into account. The positions of collision of standard and bionic fan blades were discussed, and two kinds of centrifugal fan blade wear were compared. The results show that the particles from the incident source with different positions have different processes of turning and movement when enter into the impeller. The trajectories of flow in the fan channel are significantly different for the particles with different diameters. Bionic fan blade have lower erosion rate than the standard fan blade when the particle size is 20 μm. The anti-erosion mechanism of the bionic fan blade was discussed.
文摘The formation and separation behaviors of tandem EFPs are studied by the combination of experiments and simulations.The results show that different formation and separation processes can be obtained by adjusting the double-layer liners,and simulations agree with experiments well.Then,the interaction process between the two liners is discussed in details,and the formation and separation mechanism are revealed.It can be found that there are four phases in the formation and separation processes,including impact phase,propulsion phase,slide phase and free flight phase.During the impact phase,the velocities of two liners rise in turns with kinetic energy exchange.In the propulsion phase,the axial impact becomes insignificant,but the radial interaction between two liners influences the appearance of tandem EFPs.Meanwhile,it should be mentioned that the inner surface of foregoing EFP remains to be in contact with the outer surface of following EFP in the propulsion phase,and the following one would continue to push the foregoing one for about 10μ to 20 μs,causing the velocities of following and foregoing EFPs gradually decreasing and increasing respectively.In the slide phase,an obvious relative movement occurs between the two EFPs,and there would be barely kinetic energy exchange.Then,the two EFPs separate gradually and get into the phase of free flight.Generally,if the outer and inner liners have the same thickness,the outer copper-inner copper liners form two long EFPs,the outer copper-inner steel liners become a foregoing short steel EFP and a following long copper EFP,and the outer steel-inner copper liners produce a foregoing long copper EFP and a following conical steel EFP.In addition,thickness match also has an important impact on formation appearance and separation process for both outer copperinner copper liners and outer steel-inner copper liners.With the thickness ratio of outer liner to inner liner decreasing,the length and length-diameter ratio of both foregoing and following EFPs increase gradually.
基金National Natural Science Foundation of China[grant number U1730112],China.
文摘In this paper,the ballistic impact experiments,including impact test chamber and impact double-spaced plates,were conducted to study the reaction behaviors of a novel functionally graded reactive material(FGRM),which was composed of polytetrafluoroethylene/aluminum(PTFE/Al)and PTFE/Al/bismuth trioxide(Bi_(2)O_(3)).The experiments showed that the impact direction of the FGRM had a significant effect on the reaction.With the same impact velocity,when the first impact material was PTFE/Al/Bi_(2)O_(3),compared with first impact material PTFE/Al,the FGRM induced higher overpressure in the test chamber and larger damaged area of double-spaced plates.The theoretical model,which considered the shock wave generation and propagation,the effect of the shock wave on reaction efficiency,and penetration behaviors,was developed to analyze the reaction behaviors of the FGRM.The model predicted first impact material of the FGRM with a higher shock impedance was conducive to the reaction of reactive materials.The conclusion of this study provides significant information about the design and application of reactive materials.
基金the National Natural Science Foundation of China(No.U1730112).
文摘Force chains based mesoscale simulation is conducted to investigate the response behavior of aluminumpolytetrafluoroethylene(Al-PTFE)granular composites under a low-velocity impact.A two-dimensional model followed the randomly normal distribution of real Al particles size is developed.The dynamic compressive process of Al-PTFE composites with varied Al mass fraction is simulated and validated against the experiments.The results indicate that,force chains behavior governed by the number and the size of agglomerated Al particles,significantly affects the impact response of the material.The failure mode of the material evolves from shear failure of matrix to debonding failure of particles with increasing density.A high crack area of the material is critical mechanism to arouse the initiation reaction.The damage maintained by force chains during large plastic strain builds up more local stresses concentration to enhance a possible reaction performance.In addition,simulation is performed with identical mass fraction but various Al size distribution to explore the effects of size centralization and dispersion on the mechanical properties of materials.It is found that smaller sized Al particle of composites are more preferred than its bulky material in ultimate strength.Increasing dispersed degree is facilitated to create stable force chains in samples with comparable particle number.The simulation studies provide further insights into the plastic deformation,failure mechanism,and possible energy release capacity for Al-PTFE composites,which is helpful for further design and application of reactive materials.
基金supported by the National Natural Science Foundation of China[Nos.51703153 and 21802101].
文摘In this study,waste cotton fabric was used as cellulose raw material and pretreated in aqueous NaOH/urea solution system to investigate the effect of NaOH/urea pretreatment solution on the hydrolysis of cotton fiber.The cotton fiber was pretreated with different conditions of aqueous NaOH/urea solution,and the pretreated cotton fiber was hydrolyzed under the same conditions as the original cotton fiber.The results of characterization analysis showed that water retention value of pretreated cotton fiber was higher than that of unpretreated sample.Moreover,the cotton fiber presented both a convoluted structure and a coarser surface,XRD results suggested that the crystallinity degree of cellulose decreased dramatically,more cellulose II appeared,and the hydrogen bond is broken.Among the different pretreatment conditions,the pretreatment effect was the best when the reaction temperature was 0°C,the solid-liquid ratio was 2:50,and the NaOH/urea ratio was 7:12.The hydrolysis experiments of pretreated and unpretreated cotton fibers showed that when the hydrothermal temperature was 230°C,the heat preservation was 2 h,and the hydrochloric acid concentration was 5 wt.%,the glucose yield reached 29.99%.H+could catalyze the hydrolysis of cotton fiber more effectively due to damage to crystal structure and hydrogen bonds.
基金support received from the Beijing Municipal Natural Science Foundation(Grant No.1214022).
文摘To investigate the thermal response and initiation behavior of ternary fluoropolymer-matrix PTFE/Al/W reactive materials,a research combining shock loading tests and trans-scale modelling is conducted.On the basis of a good agreement of the numerically simulated and tested shock wave propagation,the significant impact of component ratios and particle sizes on the evolution of mesoscopic temperature,hot-spots and initiation is well characterized and analyzed.Results demonstrate that as the content of W increases,the range of mesoscopic high-temperature area increases and tends to distribute more uniform,while material with smaller W particles causes more intense particle deformation and larger temperature rise.The time to reach the critical temperature shows positive correlation to the content of W,while the critical temperature of hot-spots shows negative correlation to the particle size of W.For PTFE/Al/W of high density,with the increase of W particle size,the reaction rate decrease,however the time to reach the peak reaction rate shortens.
