This study analyzed through-thickness distribution of residual stress in a 106 mm ultra-thick TC4 titanium alloy electron beam welded(EBW)joint after post weld heat treatment(PWHT)using X-ray diffraction(XRD)and deep-...This study analyzed through-thickness distribution of residual stress in a 106 mm ultra-thick TC4 titanium alloy electron beam welded(EBW)joint after post weld heat treatment(PWHT)using X-ray diffraction(XRD)and deep-hole drilling(DHD)methods,and investigated the microstructure and mechanical properties.During the PWHT at 600℃,a phase transformation(β→α)occurred in the EBW joint and affected the residual stress distribution and mechanical properties.The surface residual stress was mainly compressive stress,while the internal residual stress was mainly tensile stress in the welded joint.For the as-welded joint,the absolute value of surface residual stress was higher than the absolute value of internal residual stress.After PWHT,the residual stress in the treated joint was substantially reduced compared to the as-welded joint,particularly the surface stress,which relieved from−425 to−90 MPa.However,the residual stress relief effect had minimal positive impact on the internal region at 600℃.PWHT resulted in a shift of the joint fracture location from the fusion zone(FZ)to the base metal(BM),and therefore exerted no noticeable effect on the joint strength,but increased the joint elongation significantly.This study provides valuable insights into the regulation of residual stress distribution of ultra-thick titanium alloy plates.展开更多
Rechargeable aqueous Zn-MoO_(x)batteries are promising energy storage devices with high theoretical specific capacity and low cost.However,MoO_(3)cathodes suffer drastic capacity decay during the initial discharging/c...Rechargeable aqueous Zn-MoO_(x)batteries are promising energy storage devices with high theoretical specific capacity and low cost.However,MoO_(3)cathodes suffer drastic capacity decay during the initial discharging/charging process in conventional electrolytes,resulting in a short cycle life and challenging the development of Zn-MoO_(x)batteries.Here we comprehensively investigate the dissolution mechanism of MoO_(3)cathodes and innovatively introduce a polymer to inhibit the irreversible processes.Our findings reveal that this capacity decay originates from the irreversible Zn^(2+)/H^(+)co-intercalation/extraction process in aqueous electrolytes.Even worse,during Zn^(2+)intercalation,the formed Zn_(x)MoO_(3-x)intermediate phase with lower valence states(Mo^(5+)/Mo^(4+))experiences severe dissolution in aqueous environments.To address these challenges,we developed a first instance of coating a polyaniline(PANI)shell around the MoO_(3)nanorod effectively inhibiting these irreversible processes and protecting structural integrity during long-term cycling.Detailed structural analysis and theoretical calculations indicate that=N-groups in PANI@MoO_(3-x)simultaneously weaken H+adsorption and enhance Zn^(2+)adsorption,which endowed the PANI@MoO_(3-x)cathode with reversible Zn^(2+)/H^(+)intercalation/extraction.Consequently,the obtained PANI@MoO_(3-x)cathode delivers an excellent discharge capacity of 316.86 mA h g^(-1)at 0.1 A g^(-1)and prolonged cycling stability of 75.49%capacity retention after 1000 cycles at 5 A g^(-1).This work addresses the critical issues associated with MoO_(3)cathodes and significantly advances the understanding of competitive multi-ion energy storage mechanisms in aqueous Zn-MoO_(3)batteries.展开更多
As core components of precision-guided projectiles,projectile-borne components are highly susceptible to failure or even damage in complex high-overload environments,thereby significantly compromising launch reliabili...As core components of precision-guided projectiles,projectile-borne components are highly susceptible to failure or even damage in complex high-overload environments,thereby significantly compromising launch reliability and safety.However,accurately characterizing the mechanical behavior of propellants remains challenging due to the limitations in the current internal ballistic theory and the constraints of large-scale artillery firing experiments.This complicates the high-precision numerical modeling of projectile launch,and obstructs investigations into the failure mechanisms of projectile-borne components.Therefore,this paper identifies propellant parameters using the computational inverse method under uncertainty,further establishes high-precision numerical models of projectile launch,and explores the failure mechanisms of projectile-borne components in complex high-overload environments.First,a projectile launching experiment is meticulously designed and executed to obtain the breech pressure and muzzle velocity.Then,a general simulation model is built,and the powder burn model is used to simulate the ignition and combustion.Subsequently,the propellant parameters are effectively identified with the computational inverse method by the combination of the experiments and simulations.A high-precision numerical model of projectile launch is modified with the parameters validated by another experiment,and the high-overload characteristics during projectile launch are thoroughly analyzed based on this model.Finally,the high-overload characteristics of projectile-borne components are analyzed to elucidate the stress variation laws and to reveal the failure mechanisms influenced by time and spatial locations.This research provides an effective method for perfectly identifying propellant parameters and building high-precision numerical models of projectile launch.Additionally,it provides significant guidance for the anti-high overload design and analysis of projectile-borne components.展开更多
Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging becaus...Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.展开更多
Based on the generalized reduced R-matrix theory,the R-matrix analysis code(RAC program)was used to analyze the experimental data of all the nuclear reaction channels related to the 5 He system.The current calculation...Based on the generalized reduced R-matrix theory,the R-matrix analysis code(RAC program)was used to analyze the experimental data of all the nuclear reaction channels related to the 5 He system.The current calculations provide accurate and reliable evaluation data and are in good agreement with the experimental data.In this study,self-consistent evaluation data for each reaction were obtained using multi-channel and multi-energy fitting.In particular,the error propagation theory of generalized least squares was used to determine the error of the evaluation data and the covariance matrix of the integral cross section.This R-matrix analysis for the 5 He system has three features.First,for the first time,the error in the evaluation data of the T(d,n)^(4)He reaction cross section and the covariance matrix of the integral cross section are provided.Second,we used only one set of R-matrix parameters to depict the reaction cross section of each reaction channel of the 5 He system for the entire energy region in our work.Third,in this evaluation,we considered some of the latest measured experimental data,especially after 2000.The T(d,n)^(4)He reaction cross section at 0.1 MeV and below was carefully studied.The effect of different energy levels in T(d,n)^(4)He was analyzed,with the energy levels 3/2^(+)making a major contribution to the cross section,and the role of the S-wave and P-wave from 3/2~-determines the lean forward trend of the angular distributions at 0.01–0.1 MeV.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFC2810700)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2021193)the Science and Technology Cooperation Project between Jilin Province and Chinese Academy of Sciences(No.2024SYHZ0032).
文摘This study analyzed through-thickness distribution of residual stress in a 106 mm ultra-thick TC4 titanium alloy electron beam welded(EBW)joint after post weld heat treatment(PWHT)using X-ray diffraction(XRD)and deep-hole drilling(DHD)methods,and investigated the microstructure and mechanical properties.During the PWHT at 600℃,a phase transformation(β→α)occurred in the EBW joint and affected the residual stress distribution and mechanical properties.The surface residual stress was mainly compressive stress,while the internal residual stress was mainly tensile stress in the welded joint.For the as-welded joint,the absolute value of surface residual stress was higher than the absolute value of internal residual stress.After PWHT,the residual stress in the treated joint was substantially reduced compared to the as-welded joint,particularly the surface stress,which relieved from−425 to−90 MPa.However,the residual stress relief effect had minimal positive impact on the internal region at 600℃.PWHT resulted in a shift of the joint fracture location from the fusion zone(FZ)to the base metal(BM),and therefore exerted no noticeable effect on the joint strength,but increased the joint elongation significantly.This study provides valuable insights into the regulation of residual stress distribution of ultra-thick titanium alloy plates.
基金supported by National Natural Science Foundation of China(22209064,52071171,and 52202248)the Fundamental Research Funds for Public Universities in Liaoning(LJKLJ202434)+6 种基金the Australian Research Council(ARC)through Future Fellowship(FT210100298)Discovery Project(DP220100603)Linkage Project(LP210200504,LP220100088,LP230200897)Industrial Transformation Research Hub(IH240100009)schemesthe Australian Government through the Cooperative Research Centres Projects(CRCPXIII000077)the Australian Renewable Energy Agency(ARENA)as part of ARENA’s Transformative Research Accelerating Commercialisation Program(TM021)European Commission’s Australia-Spain Network for Innovation and Research Excellence(AuSpire)。
文摘Rechargeable aqueous Zn-MoO_(x)batteries are promising energy storage devices with high theoretical specific capacity and low cost.However,MoO_(3)cathodes suffer drastic capacity decay during the initial discharging/charging process in conventional electrolytes,resulting in a short cycle life and challenging the development of Zn-MoO_(x)batteries.Here we comprehensively investigate the dissolution mechanism of MoO_(3)cathodes and innovatively introduce a polymer to inhibit the irreversible processes.Our findings reveal that this capacity decay originates from the irreversible Zn^(2+)/H^(+)co-intercalation/extraction process in aqueous electrolytes.Even worse,during Zn^(2+)intercalation,the formed Zn_(x)MoO_(3-x)intermediate phase with lower valence states(Mo^(5+)/Mo^(4+))experiences severe dissolution in aqueous environments.To address these challenges,we developed a first instance of coating a polyaniline(PANI)shell around the MoO_(3)nanorod effectively inhibiting these irreversible processes and protecting structural integrity during long-term cycling.Detailed structural analysis and theoretical calculations indicate that=N-groups in PANI@MoO_(3-x)simultaneously weaken H+adsorption and enhance Zn^(2+)adsorption,which endowed the PANI@MoO_(3-x)cathode with reversible Zn^(2+)/H^(+)intercalation/extraction.Consequently,the obtained PANI@MoO_(3-x)cathode delivers an excellent discharge capacity of 316.86 mA h g^(-1)at 0.1 A g^(-1)and prolonged cycling stability of 75.49%capacity retention after 1000 cycles at 5 A g^(-1).This work addresses the critical issues associated with MoO_(3)cathodes and significantly advances the understanding of competitive multi-ion energy storage mechanisms in aqueous Zn-MoO_(3)batteries.
基金Project supported by the National Natural Science Foundation of China (No. 12302435)。
文摘As core components of precision-guided projectiles,projectile-borne components are highly susceptible to failure or even damage in complex high-overload environments,thereby significantly compromising launch reliability and safety.However,accurately characterizing the mechanical behavior of propellants remains challenging due to the limitations in the current internal ballistic theory and the constraints of large-scale artillery firing experiments.This complicates the high-precision numerical modeling of projectile launch,and obstructs investigations into the failure mechanisms of projectile-borne components.Therefore,this paper identifies propellant parameters using the computational inverse method under uncertainty,further establishes high-precision numerical models of projectile launch,and explores the failure mechanisms of projectile-borne components in complex high-overload environments.First,a projectile launching experiment is meticulously designed and executed to obtain the breech pressure and muzzle velocity.Then,a general simulation model is built,and the powder burn model is used to simulate the ignition and combustion.Subsequently,the propellant parameters are effectively identified with the computational inverse method by the combination of the experiments and simulations.A high-precision numerical model of projectile launch is modified with the parameters validated by another experiment,and the high-overload characteristics during projectile launch are thoroughly analyzed based on this model.Finally,the high-overload characteristics of projectile-borne components are analyzed to elucidate the stress variation laws and to reveal the failure mechanisms influenced by time and spatial locations.This research provides an effective method for perfectly identifying propellant parameters and building high-precision numerical models of projectile launch.Additionally,it provides significant guidance for the anti-high overload design and analysis of projectile-borne components.
基金financially supported by the China Postdoctoral Science Foundation(No.2024M751205)。
文摘Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.
基金supported by Science Challenge Project(No.TZ20180001)。
文摘Based on the generalized reduced R-matrix theory,the R-matrix analysis code(RAC program)was used to analyze the experimental data of all the nuclear reaction channels related to the 5 He system.The current calculations provide accurate and reliable evaluation data and are in good agreement with the experimental data.In this study,self-consistent evaluation data for each reaction were obtained using multi-channel and multi-energy fitting.In particular,the error propagation theory of generalized least squares was used to determine the error of the evaluation data and the covariance matrix of the integral cross section.This R-matrix analysis for the 5 He system has three features.First,for the first time,the error in the evaluation data of the T(d,n)^(4)He reaction cross section and the covariance matrix of the integral cross section are provided.Second,we used only one set of R-matrix parameters to depict the reaction cross section of each reaction channel of the 5 He system for the entire energy region in our work.Third,in this evaluation,we considered some of the latest measured experimental data,especially after 2000.The T(d,n)^(4)He reaction cross section at 0.1 MeV and below was carefully studied.The effect of different energy levels in T(d,n)^(4)He was analyzed,with the energy levels 3/2^(+)making a major contribution to the cross section,and the role of the S-wave and P-wave from 3/2~-determines the lean forward trend of the angular distributions at 0.01–0.1 MeV.
