The current work addresses the challenge of elucidating the performance of fluoroelastomers within the HMX(octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)based polymer-bonded explosives(PBXs).To simulate the confine...The current work addresses the challenge of elucidating the performance of fluoroelastomers within the HMX(octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)based polymer-bonded explosives(PBXs).To simulate the confined interface in PBXs,bilayer films of F2314/HMX and F2311/HMX were designed.Neutron reflectivity(NR),nanoindentation,and X-ray reflectivity(XRR)were employed to examine the layer thickness,interface characteristics,diffusion behavior,and surface morphology of the bilayers.NR measurements revealed interface thicknesses of 45Å and 98Å for F2314/HMX and F2311/HMX,respectively,indicating deeper penetration of F2311 into the HMX matrix.NR also suggested a denser polymer network with a higher scattering length density(SLD)near the HMX interface for both fluoroelastomers,while the bound layer of F2311 was notably thicker.Nanoindentation cross-checks and confirms the presence of a bound layer,highlighting the differences in stiffness and diffusion ability between the two polymers.The consistency between the NR and nanoindentation results suggests that F2311 demonstrates better flexibility and elasticity,whereas F2314 is stiffer and more plastic.Accordingly,the structures and performances of different fluoroelastomers at the HMX interface are discussed,which can provide valuable insights into the selection of binders for PBX formulations tailored to specific applications.展开更多
For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To...For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance （Rs） on high-frequency （SMHz） capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the CHF-CLF capacitance and the conductance method are 2 ×1012 e V-1 cm-2 and 0.94 × 1012 eV-1 cm-2, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.展开更多
We investigate the influence of interface charge on electrical performance of NbAIO/A1GaN/GaN metal-oxide- semiconductor high electron mobility transistors （MOSHEMTs）. Through C-V measurements and simulations, we fi...We investigate the influence of interface charge on electrical performance of NbAIO/A1GaN/GaN metal-oxide- semiconductor high electron mobility transistors （MOSHEMTs）. Through C-V measurements and simulations, we find that the donor-type interface fixed charge density Qit of 2.2 × 10^13 cm^-2 exists at the NbA10/A1GaN interface, which induces the shift of the threshold voltage much more negative. Furthermore, a trap density of approximately 0.43 × 10^13-1.14 ×10^13 cm^-2 eV^-1 is obtained at the NaA10/AlGaN interface, which is consistent with the frequency-dependent capacitance and conductance measurement results.展开更多
In situ x-ray diffraction electrochemical method is used to study the activation of silver electrode in KCl solution and UPD lead on silver electrode surface. We found that the activation makes the silver crystal thic...In situ x-ray diffraction electrochemical method is used to study the activation of silver electrode in KCl solution and UPD lead on silver electrode surface. We found that the activation makes the silver crystal thicker in (111), and the arrangement of water molecules on the silver electrode surface with UPD lead is partially ordered.展开更多
Laser fusion brazing welding was proposed.Galvanized steel/AA6061 lapped joint was obtained by laser fusion brazing welding technique using the laser-induced aluminium molten pool spreading and wetting the solid steel...Laser fusion brazing welding was proposed.Galvanized steel/AA6061 lapped joint was obtained by laser fusion brazing welding technique using the laser-induced aluminium molten pool spreading and wetting the solid steel surface.Wide joint interface was formed using the rectangular laser beam coupled with the synchronous powder feeding.The result showed that the tiny structure with the composition of a-Al and Al–Si eutectic was formed in the weld close to the Al side.And close to the steel side,a layer of compact Fe–Al–Si intermetallics,including the Al-rich FeAl3,Fe2Al5 phases and Al–Fe–Si s1 phase,was generated with the thickness of about 10–20 lm.Transverse tensile shows the brittlefractured characteristic along to the seam/steel interface with the maximum yield strength of 152.5 MPa due to the existence of hardening phases s1 and Al–Fe intermetallics.展开更多
The global trends towards improving fuel efficiency and reducing CO;emissions are the key drivers for lightweight solutions. In sheet metal processing, this can be achieved by the use of materials with a supreme stren...The global trends towards improving fuel efficiency and reducing CO;emissions are the key drivers for lightweight solutions. In sheet metal processing, this can be achieved by the use of materials with a supreme strength-toweight and stiffness-to-weight ratio. Besides monolithic materials such as high-strength or light metals, in particular metal–plastic composite sheets are able to provide outstanding mechanical properties. Thus, the adaption of conventional, wellestablished forming methods for the processing of hybrid sheet metals is a current challenge for the sheet metal working industry. In this work, the planning phase for a conventional sheet metal forming process is studied aiming at the forming of metal–plastic composite sheets. The single process steps like material characterization, FE analysis, tool design and development of robust process parameters are studied in detail and adapted to the specific properties of metal–plastic composites. In material characterization, the model of the hybrid laminate needs to represent not only the mechanical properties of the individual combined materials, but also needs to reflect the behaviour of the interface zone between them.Based on experience, there is a strong dependency on temperature as well as strain rate. While monolithic materials show a moderate anisotropic behaviour, loads on laminates in different directions generate different strain states and completely different failure modes. During the FE analysis, thermo-mechanic and thermo-dynamic effects influence the temperature distribution within tool and work pieces and subsequently the forming behaviour. During try out and production phase,those additional influencing factors are limiting the process window even more and therefore need to be considered for the design of a robust forming process. A roadmap for sheet metal forming adjusted to metal–plastic composites is presented in this paper.展开更多
As promising candidates for high-energy-density lithium-ion batteries,both silicon(Si)anodes and nickel-rich cathodes face significant challenges due to structural instability arising from interphases.In this study,we...As promising candidates for high-energy-density lithium-ion batteries,both silicon(Si)anodes and nickel-rich cathodes face significant challenges due to structural instability arising from interphases.In this study,we introduced tetravinylsilane(TVSi)as a multifunctional electrolyte additive to engineer tai-lored interphases simultaneously on Si anode and LiNi_(0.92)Mn_(0.05)Co_(0.03)O_(2)cathode,thereby enhancing their electrochemical performance.On one front,TVSi underwent polymerization,leading to the for-mation of a composite solid electrolyte interphase(SEI)with an interpenetrating network structure on the Si surface.This SEI effectively accommodated volume changes during cycling,which inhibited SEI growth,hence,preserving the battery capacity.On the other hand,the TVSi-induced cathode electrolyte interphase(CEI)exhibited a dense structure com-prising a chemically bonded silicate-silane polymer.This CEI effectively mitigated transition metal disso-lution by scavenging hydrofluoric acid(HF)and re-duced irreversible phase transitions by minimizing side reactions.As a result of the enhanced interfacial stability achieved on both electrodes,TVSi enabled improved performance in full cells fabricated with a LiNi_(0.92)Mn_(0.05)Co_(0.03)O_(2)cathode paired with a Si anode.This multifunctional additive strategy offers a novel perspective on additive design for high-energy-density lithium-ion batteries,showcasing its potential for advancing battery technology.展开更多
Sum-frequency generation(SFG)is a second-order nonlinear process widely used for characterizing surfaces and interfaces with monolayer sensitivity.Recently,optical field enhancement in plasmonic nanocavities has enabl...Sum-frequency generation(SFG)is a second-order nonlinear process widely used for characterizing surfaces and interfaces with monolayer sensitivity.Recently,optical field enhancement in plasmonic nanocavities has enabled SFG with continuous wave(CW)lasers from nanoscale areas of molecules,promising applications like nanoscale SFG spectroscopy and coherent upconversion for mid-infrared detection at visible frequencies.Here,we demonstrate CW SFG from individual nanoparticle-on-mirror(NPoM)cavities,which are resonant at visible frequencies and filled with a monolayer of molecules,when placed beneath a metal scanning probe tip.The tip acts as an efficient broadband antenna,focusing incident CW infrared illumination onto the nanocavity.The cascaded near-field enhancement within the NPoM nanocavity yields nonlinear optical responses across a broad range of infrared frequencies,achieving SFG enhancements of up to 14 orders of magnitude.Further,nanomechanical positioning of the tip allows for in-operando control of SFG by tuning the local field enhancement rather than the illumination intensities.The versatility of tipenhanced nanocavities allows for SFG studies of a wide range of molecular species in the few-molecule regime without the need for complex nanofabrication.Our results also promise SFG nanoimaging with tips providing strong visible and IR field enhancement at their apex,offering a robust platform for future applications in nonlinear nanooptics.展开更多
In order to cvaluate the fiber / matrix interfaccs in a fiber reinforced compo site, a mathematical algorithm is prescnted for predicting the scattering cross scction of a cylindrical three-layered medium and the soun...In order to cvaluate the fiber / matrix interfaccs in a fiber reinforced compo site, a mathematical algorithm is prescnted for predicting the scattering cross scction of a cylindrical three-layered medium and the sound attenuation due to scattering in the composite. When the thickness of the fiber / matrix interface layer is small compared to the wavelength, two stiffness constants are used to simulate the boundary condi tions and a simplified method for predicting the sound scattering is developed. Nu mcrical computations have been made for the relations of longitudinal wave attcnuation coefficients in a glass fiber / aluminum composite with the interface properties and wave frequency.展开更多
基金supported in part by the National Natural Science Foundation of China(Nos.12335018,12105264,and 12275248)NSAF Joint Fund Project(Nos.U2230107,U1730244,U2130207)+1 种基金Innovation and Development Fund of China Academy of Engineering Physics(No.CXKS20240052)Central Guidance for Local Science and Technology Development Fund Project(No.2023ZYDF075).
文摘The current work addresses the challenge of elucidating the performance of fluoroelastomers within the HMX(octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)based polymer-bonded explosives(PBXs).To simulate the confined interface in PBXs,bilayer films of F2314/HMX and F2311/HMX were designed.Neutron reflectivity(NR),nanoindentation,and X-ray reflectivity(XRR)were employed to examine the layer thickness,interface characteristics,diffusion behavior,and surface morphology of the bilayers.NR measurements revealed interface thicknesses of 45Å and 98Å for F2314/HMX and F2311/HMX,respectively,indicating deeper penetration of F2311 into the HMX matrix.NR also suggested a denser polymer network with a higher scattering length density(SLD)near the HMX interface for both fluoroelastomers,while the bound layer of F2311 was notably thicker.Nanoindentation cross-checks and confirms the presence of a bound layer,highlighting the differences in stiffness and diffusion ability between the two polymers.The consistency between the NR and nanoindentation results suggests that F2311 demonstrates better flexibility and elasticity,whereas F2314 is stiffer and more plastic.Accordingly,the structures and performances of different fluoroelastomers at the HMX interface are discussed,which can provide valuable insights into the selection of binders for PBX formulations tailored to specific applications.
基金Supported by the Natural Science Foundation of Jiangxi Province under Grant No 20133ACB20005the Key Program of National Natural Science Foundation of China under Grant No 41330318+3 种基金the Key Program of Science and Technology Research of Ministry of Education under Grant No NRE1515the Foundation of Training Academic and Technical Leaders for Main Majors of Jiangxi Province under Grant No 20142BCB22006the Research Foundation of Education Bureau of Jiangxi Province under Grant No GJJ14501the Engineering Research Center of Nuclear Technology Application(East China Institute of Technology)Ministry of Education under Grant NoHJSJYB2016-1
文摘For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance （Rs） on high-frequency （SMHz） capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the CHF-CLF capacitance and the conductance method are 2 ×1012 e V-1 cm-2 and 0.94 × 1012 eV-1 cm-2, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.
基金Supported by the Basic Science Research Fund for the Central Universities of China under Grant No JB141104
文摘We investigate the influence of interface charge on electrical performance of NbAIO/A1GaN/GaN metal-oxide- semiconductor high electron mobility transistors （MOSHEMTs）. Through C-V measurements and simulations, we find that the donor-type interface fixed charge density Qit of 2.2 × 10^13 cm^-2 exists at the NbA10/A1GaN interface, which induces the shift of the threshold voltage much more negative. Furthermore, a trap density of approximately 0.43 × 10^13-1.14 ×10^13 cm^-2 eV^-1 is obtained at the NaA10/AlGaN interface, which is consistent with the frequency-dependent capacitance and conductance measurement results.
基金This paper was suported by the National Natural Science Foundation of China.
文摘In situ x-ray diffraction electrochemical method is used to study the activation of silver electrode in KCl solution and UPD lead on silver electrode surface. We found that the activation makes the silver crystal thicker in (111), and the arrangement of water molecules on the silver electrode surface with UPD lead is partially ordered.
基金financially supported by the National Natural Science Foundation of China (No.50875005)Beijing Natural Science Foundation (No.3102005)
文摘Laser fusion brazing welding was proposed.Galvanized steel/AA6061 lapped joint was obtained by laser fusion brazing welding technique using the laser-induced aluminium molten pool spreading and wetting the solid steel surface.Wide joint interface was formed using the rectangular laser beam coupled with the synchronous powder feeding.The result showed that the tiny structure with the composition of a-Al and Al–Si eutectic was formed in the weld close to the Al side.And close to the steel side,a layer of compact Fe–Al–Si intermetallics,including the Al-rich FeAl3,Fe2Al5 phases and Al–Fe–Si s1 phase,was generated with the thickness of about 10–20 lm.Transverse tensile shows the brittlefractured characteristic along to the seam/steel interface with the maximum yield strength of 152.5 MPa due to the existence of hardening phases s1 and Al–Fe intermetallics.
基金the German Research Foundation (DFG)German Federation of Industrial Research Associations (AiF)the European Research Association for Sheet Metal Working (EFB)
文摘The global trends towards improving fuel efficiency and reducing CO;emissions are the key drivers for lightweight solutions. In sheet metal processing, this can be achieved by the use of materials with a supreme strength-toweight and stiffness-to-weight ratio. Besides monolithic materials such as high-strength or light metals, in particular metal–plastic composite sheets are able to provide outstanding mechanical properties. Thus, the adaption of conventional, wellestablished forming methods for the processing of hybrid sheet metals is a current challenge for the sheet metal working industry. In this work, the planning phase for a conventional sheet metal forming process is studied aiming at the forming of metal–plastic composite sheets. The single process steps like material characterization, FE analysis, tool design and development of robust process parameters are studied in detail and adapted to the specific properties of metal–plastic composites. In material characterization, the model of the hybrid laminate needs to represent not only the mechanical properties of the individual combined materials, but also needs to reflect the behaviour of the interface zone between them.Based on experience, there is a strong dependency on temperature as well as strain rate. While monolithic materials show a moderate anisotropic behaviour, loads on laminates in different directions generate different strain states and completely different failure modes. During the FE analysis, thermo-mechanic and thermo-dynamic effects influence the temperature distribution within tool and work pieces and subsequently the forming behaviour. During try out and production phase,those additional influencing factors are limiting the process window even more and therefore need to be considered for the design of a robust forming process. A roadmap for sheet metal forming adjusted to metal–plastic composites is presented in this paper.
基金supported by the National Natural Science Foundation of China(NSFCgrant no.52303263)+1 种基金the Shenzhen Science and Technology Research Grants,China(grant no.JCYJ20200109140416788)the Soft Science Research Project of Guangdong Province,China(grant no.2017B030301013).
文摘As promising candidates for high-energy-density lithium-ion batteries,both silicon(Si)anodes and nickel-rich cathodes face significant challenges due to structural instability arising from interphases.In this study,we introduced tetravinylsilane(TVSi)as a multifunctional electrolyte additive to engineer tai-lored interphases simultaneously on Si anode and LiNi_(0.92)Mn_(0.05)Co_(0.03)O_(2)cathode,thereby enhancing their electrochemical performance.On one front,TVSi underwent polymerization,leading to the for-mation of a composite solid electrolyte interphase(SEI)with an interpenetrating network structure on the Si surface.This SEI effectively accommodated volume changes during cycling,which inhibited SEI growth,hence,preserving the battery capacity.On the other hand,the TVSi-induced cathode electrolyte interphase(CEI)exhibited a dense structure com-prising a chemically bonded silicate-silane polymer.This CEI effectively mitigated transition metal disso-lution by scavenging hydrofluoric acid(HF)and re-duced irreversible phase transitions by minimizing side reactions.As a result of the enhanced interfacial stability achieved on both electrodes,TVSi enabled improved performance in full cells fabricated with a LiNi_(0.92)Mn_(0.05)Co_(0.03)O_(2)cathode paired with a Si anode.This multifunctional additive strategy offers a novel perspective on additive design for high-energy-density lithium-ion batteries,showcasing its potential for advancing battery technology.
基金The work received support from Grant CEX2020-001038-M funded by MICIU/AEI/10.13039/501100011033 and Grant PID2021-123949OB-I00(NANOSPEC)funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EUP.R.acknowledges financial support from the Swiss National Science Foundation(Grant No.206926)+2 种基金the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No.101065661I.N.acknowledges financial support from the Ministerium für Kultur und Wissenschaft des Landes Nordrhein-Westfalen as well as from the Deutsche Forschungsgemeinschaft(project number 467576442)JA and IP acknowledge funding from project IT1526-22 from the Department of Education of the Basque Government,from Elkartek project“u4smart"from the Dept.of Industry of the Basque Government,and from grant PID2022-139579NB-I00 funded by MCIN/AEI/10.13039/501100011033 and by“ERDF A way of making Europe”.
文摘Sum-frequency generation(SFG)is a second-order nonlinear process widely used for characterizing surfaces and interfaces with monolayer sensitivity.Recently,optical field enhancement in plasmonic nanocavities has enabled SFG with continuous wave(CW)lasers from nanoscale areas of molecules,promising applications like nanoscale SFG spectroscopy and coherent upconversion for mid-infrared detection at visible frequencies.Here,we demonstrate CW SFG from individual nanoparticle-on-mirror(NPoM)cavities,which are resonant at visible frequencies and filled with a monolayer of molecules,when placed beneath a metal scanning probe tip.The tip acts as an efficient broadband antenna,focusing incident CW infrared illumination onto the nanocavity.The cascaded near-field enhancement within the NPoM nanocavity yields nonlinear optical responses across a broad range of infrared frequencies,achieving SFG enhancements of up to 14 orders of magnitude.Further,nanomechanical positioning of the tip allows for in-operando control of SFG by tuning the local field enhancement rather than the illumination intensities.The versatility of tipenhanced nanocavities allows for SFG studies of a wide range of molecular species in the few-molecule regime without the need for complex nanofabrication.Our results also promise SFG nanoimaging with tips providing strong visible and IR field enhancement at their apex,offering a robust platform for future applications in nonlinear nanooptics.
文摘In order to cvaluate the fiber / matrix interfaccs in a fiber reinforced compo site, a mathematical algorithm is prescnted for predicting the scattering cross scction of a cylindrical three-layered medium and the sound attenuation due to scattering in the composite. When the thickness of the fiber / matrix interface layer is small compared to the wavelength, two stiffness constants are used to simulate the boundary condi tions and a simplified method for predicting the sound scattering is developed. Nu mcrical computations have been made for the relations of longitudinal wave attcnuation coefficients in a glass fiber / aluminum composite with the interface properties and wave frequency.
