Numerical simulation is one of the important auxiliary methods for studying materials-related problems. In this study, phase field simulation was employed to investigate the refinement behavior of BAg55CuZn-x B brazin...Numerical simulation is one of the important auxiliary methods for studying materials-related problems. In this study, phase field simulation was employed to investigate the refinement behavior of BAg55CuZn-x B brazing alloys. Simulation and experimental studies were conducted for B contents ranging from 0 wt.% to 0.2 wt.%. The results demonstrated that the addition of 0.05 wt.% B in the brazing alloy leads to a significant refinement effect. As the B content increases, the grain size further reduces, and a refinement stagnation phenomenon occurs after exceeding 0.15 wt.%. The solidification process of brazing alloys with different B content was predicted by simulation, and the simulation results showed that with the increase of B content, the initial number of nucleation increased, and the radius of the dendrite tip decreased. The simulation results are in good agreement with the experimental findings, providing further evidence of the refining effect of the B element and the reliable predictive capability of the phase field model.展开更多
By using a self-developed IF power and a ASTM contact material experimental system of small-capacity and variable frequency,the value of arcing characteristics and the welding force of the silver-based contact materia...By using a self-developed IF power and a ASTM contact material experimental system of small-capacity and variable frequency,the value of arcing characteristics and the welding force of the silver-based contact material are acquired under low voltage,resistive load and small current at 400 Hz and 50 Hz. By means of an electricity-ray analytical balance,SEM and EDAX,the weighing values of the contact materials and the changes of AgCdO,AgNi,AgC and AgW contact material surface profile and micro-area constituent are obtained and analyzed. The arc erosion causes of silver-based alloy contact materials at 400 Hz and 50 Hz are also discussed.展开更多
Ti_(3)AlC_(2)-reinforced Ag-based composites,which are used as sliding current collectors,electrical contacts,and electrode materials,exhibit remarkable performances.However,the interfacial reactions between Ag and Ti...Ti_(3)AlC_(2)-reinforced Ag-based composites,which are used as sliding current collectors,electrical contacts,and electrode materials,exhibit remarkable performances.However,the interfacial reactions between Ag and Ti_(3)AlC_(2) significantly degrade the electrical and thermal properties of these composites.To diminish these interfacial reactions,we fabricated carbon-coated Ti_(3)AlC_(2) particles(C@Ti_(3)AlC_(2))as reinforcement and prepared Ag–10wt%C@Ti_(3)AlC_(2) composites with carbon-layer thicknesses ranging from 50–200 nm.Compared with the uncoated Ag–Ti_(3)AlC_(2) composite,Ag–C@Ti_(3)AlC_(2) was found to have a better distribution of Ti_(3)AlC_(2) particles.With increases in the carbon-layer thickness,the Vickers hardness value and relative density of Ag–C@Ti_(3)AlC_(2) gradually decreases.With a carbon-layer thickness of 150 nm,we obtained the lowest resistivity of Ag–C@Ti_(3)AlC_(2) of 29.4135.5×10^(−9)Ω·m,which is half that of Ag–Ti_(3)AlC_(2)(66.7×10^(−9)Ω·m).The thermal conductivity of Ag–C@Ti_(3)AlC_(2) reached a maximum value of 135.5 W·m^(−1)·K^(−1) with a 200-nm carbon coating(~1.8 times that of Ag–Ti_(3)AlC_(2)).These results indicate that the carbon-coating method is a feasible strategy for improving the performance of Ag–C@Ti_(3)AlC_(2) composites.展开更多
Silver-based quantum dots(QDs)such as Ag2S,Ag2Se,and Ag2Te,which emit in the second near-infrared window(NIR-II,900–1700 nm),have attracted great research interest due to their prominent optical properties and eco-fr...Silver-based quantum dots(QDs)such as Ag2S,Ag2Se,and Ag2Te,which emit in the second near-infrared window(NIR-II,900–1700 nm),have attracted great research interest due to their prominent optical properties and eco-friendly compositions.Over the past decade,the controllable synthesis,bandgap modulation,and fluorescence improvement of NIR-II Ag-based QDs have greatly promoted their practical applications.In this review,we summarize the development process and latest achievements of NIR-II Ag-based QDs,covering major synthesis techniques for fabricating NIR-II Ag-based QDs,general methods for improving their fluorescence properties and recent advances in the applications of NIR-II Ag-based QDs from bioimaging to optoelectronic devices.Finally,we discuss the challenges and prospects of NIR-II Ag-based QDs in their optical properties and applications.This review aims to present synthesis and modification strategies and future application prospects for NIR-II Ag-based QDs,providing guidance for the design and integration of fluorescent probes in NIR-II window.展开更多
This paper reports on the design,fabrication,RF measurement,and high-power test of a prototype accelerator—such as 11.424 GHz with 12 cells—and a traveling wave of two halves.It was found that the unloaded gradient ...This paper reports on the design,fabrication,RF measurement,and high-power test of a prototype accelerator—such as 11.424 GHz with 12 cells—and a traveling wave of two halves.It was found that the unloaded gradient reached 103 MV/m during the high-power test and the measured breakdown rate,after 3.17×10^(7) pulses,was 1.62×10^(-4)/pulse/m at 94 MV/m and a 90 ns pulse length.We thus concluded that the high-gradient two-half linear accelerator is cost-effective,especially in high-frequency RF linear acceleration.Finally,we suggest that silverbased alloy brazing can further reduce costs.展开更多
Melting temperature, spreadability, mechanical properties and the microstructures of joints brazed with silver-base filler metals including different amounts of Ga and/or In were studied respectively in this paper, an...Melting temperature, spreadability, mechanical properties and the microstructures of joints brazed with silver-base filler metals including different amounts of Ga and/or In were studied respectively in this paper, and the results show that the melting temperature of the silver-base filler metals is decreased, spreadability of the silver-base filler metals is improved, and the microstructures of silver-base filh, r metals are refined obviously with the addition of Ga and/or In. Using copper and brass plates as base metal and brazing with flame method, the mechanical properties of the lap-joint and butt joint were also examined and analyzed respectively, and the results indicate that the fracture position of two kinds of brazed joints occurred on the base metal, except for the lap-joint of brass, which shows better mechanical properties of the joints brazed with the silver- based filler metals including Ga. For the lap-joint of brass, the tensile strength gradually increased with the increase of Ga content, while the addition of In has little effect on mechanical properties. It is also found that the best comprehensive properties of cadmium-free Ag-Cu-Zn filler metals are obtained when Ga content is about 3.0 wt. % and In content is between 1.5 wt. % and 2. 0 wt. %.展开更多
基金the Major Science and Technology Project of Henan Province.(No.221100230300).
文摘Numerical simulation is one of the important auxiliary methods for studying materials-related problems. In this study, phase field simulation was employed to investigate the refinement behavior of BAg55CuZn-x B brazing alloys. Simulation and experimental studies were conducted for B contents ranging from 0 wt.% to 0.2 wt.%. The results demonstrated that the addition of 0.05 wt.% B in the brazing alloy leads to a significant refinement effect. As the B content increases, the grain size further reduces, and a refinement stagnation phenomenon occurs after exceeding 0.15 wt.%. The solidification process of brazing alloys with different B content was predicted by simulation, and the simulation results showed that with the increase of B content, the initial number of nucleation increased, and the radius of the dendrite tip decreased. The simulation results are in good agreement with the experimental findings, providing further evidence of the refining effect of the B element and the reliable predictive capability of the phase field model.
基金supported by the Hunan Natural Science Foundation in China (No.05JJ40068)
文摘By using a self-developed IF power and a ASTM contact material experimental system of small-capacity and variable frequency,the value of arcing characteristics and the welding force of the silver-based contact material are acquired under low voltage,resistive load and small current at 400 Hz and 50 Hz. By means of an electricity-ray analytical balance,SEM and EDAX,the weighing values of the contact materials and the changes of AgCdO,AgNi,AgC and AgW contact material surface profile and micro-area constituent are obtained and analyzed. The arc erosion causes of silver-based alloy contact materials at 400 Hz and 50 Hz are also discussed.
基金financial support of the National Natural Science Foundation of China(Nos.51731004 and 51671054)the Natural Science Foundation of Jiangsu Province(No.BK20181285)the Fundamental Research Funds for the Central Universities,China(No.2242019K 40056).
文摘Ti_(3)AlC_(2)-reinforced Ag-based composites,which are used as sliding current collectors,electrical contacts,and electrode materials,exhibit remarkable performances.However,the interfacial reactions between Ag and Ti_(3)AlC_(2) significantly degrade the electrical and thermal properties of these composites.To diminish these interfacial reactions,we fabricated carbon-coated Ti_(3)AlC_(2) particles(C@Ti_(3)AlC_(2))as reinforcement and prepared Ag–10wt%C@Ti_(3)AlC_(2) composites with carbon-layer thicknesses ranging from 50–200 nm.Compared with the uncoated Ag–Ti_(3)AlC_(2) composite,Ag–C@Ti_(3)AlC_(2) was found to have a better distribution of Ti_(3)AlC_(2) particles.With increases in the carbon-layer thickness,the Vickers hardness value and relative density of Ag–C@Ti_(3)AlC_(2) gradually decreases.With a carbon-layer thickness of 150 nm,we obtained the lowest resistivity of Ag–C@Ti_(3)AlC_(2) of 29.4135.5×10^(−9)Ω·m,which is half that of Ag–Ti_(3)AlC_(2)(66.7×10^(−9)Ω·m).The thermal conductivity of Ag–C@Ti_(3)AlC_(2) reached a maximum value of 135.5 W·m^(−1)·K^(−1) with a 200-nm carbon coating(~1.8 times that of Ag–Ti_(3)AlC_(2)).These results indicate that the carbon-coating method is a feasible strategy for improving the performance of Ag–C@Ti_(3)AlC_(2) composites.
基金supported the National Natural Science Foundation of China(Nos.21934007 and 22271308)Natural Science Foundation of Jiangsu province(Nos.BK20222016 and BE2022753)China Postdoctoral Science Foundation(Nos.2022M720105 and 2023T160470).
文摘Silver-based quantum dots(QDs)such as Ag2S,Ag2Se,and Ag2Te,which emit in the second near-infrared window(NIR-II,900–1700 nm),have attracted great research interest due to their prominent optical properties and eco-friendly compositions.Over the past decade,the controllable synthesis,bandgap modulation,and fluorescence improvement of NIR-II Ag-based QDs have greatly promoted their practical applications.In this review,we summarize the development process and latest achievements of NIR-II Ag-based QDs,covering major synthesis techniques for fabricating NIR-II Ag-based QDs,general methods for improving their fluorescence properties and recent advances in the applications of NIR-II Ag-based QDs from bioimaging to optoelectronic devices.Finally,we discuss the challenges and prospects of NIR-II Ag-based QDs in their optical properties and applications.This review aims to present synthesis and modification strategies and future application prospects for NIR-II Ag-based QDs,providing guidance for the design and integration of fluorescent probes in NIR-II window.
基金supported by the National Natural Science Foundation of China(No.11922504)。
文摘This paper reports on the design,fabrication,RF measurement,and high-power test of a prototype accelerator—such as 11.424 GHz with 12 cells—and a traveling wave of two halves.It was found that the unloaded gradient reached 103 MV/m during the high-power test and the measured breakdown rate,after 3.17×10^(7) pulses,was 1.62×10^(-4)/pulse/m at 94 MV/m and a 90 ns pulse length.We thus concluded that the high-gradient two-half linear accelerator is cost-effective,especially in high-frequency RF linear acceleration.Finally,we suggest that silverbased alloy brazing can further reduce costs.
文摘Melting temperature, spreadability, mechanical properties and the microstructures of joints brazed with silver-base filler metals including different amounts of Ga and/or In were studied respectively in this paper, and the results show that the melting temperature of the silver-base filler metals is decreased, spreadability of the silver-base filler metals is improved, and the microstructures of silver-base filh, r metals are refined obviously with the addition of Ga and/or In. Using copper and brass plates as base metal and brazing with flame method, the mechanical properties of the lap-joint and butt joint were also examined and analyzed respectively, and the results indicate that the fracture position of two kinds of brazed joints occurred on the base metal, except for the lap-joint of brass, which shows better mechanical properties of the joints brazed with the silver- based filler metals including Ga. For the lap-joint of brass, the tensile strength gradually increased with the increase of Ga content, while the addition of In has little effect on mechanical properties. It is also found that the best comprehensive properties of cadmium-free Ag-Cu-Zn filler metals are obtained when Ga content is about 3.0 wt. % and In content is between 1.5 wt. % and 2. 0 wt. %.
