The surface infiltrated composite (Ni/WC) layers on gray iron substrate were fabricated through a vacuum infiltration casting technique (VICT) using Ni-based composite powder with different WC particles content as...The surface infiltrated composite (Ni/WC) layers on gray iron substrate were fabricated through a vacuum infiltration casting technique (VICT) using Ni-based composite powder with different WC particles content as raw materials.The microstructures of surface infiltrated composite layer,the interface structures between surface composite layer and the substrate,the changes of macro-hardness with the increasing of WC content and the micro-hardness distribution are investigated.The infiltrated composite layer includes a surface composite layer and a transition layer,and the thickness of the transition layer decreases with the increasing content of WC.The thickness of transition layer with 20%WC content in the surface infiltrated composite layer was 170 μm which was the thickest for all transition layers with different WC content.The surface composite layer was mainly composed of WC,W2C,FeB and NiB,along with Ni-Cr-Fe,Ni (Cr) solid solution,Ni (Si) solid solution and Ni (Fe) solid solution.The transition layer was composed of Ni (Cr) solid solution,Ni (Fe) solid solution,Ni (Si) solid solution,Fe (Ni) solid solution and eutectic.The surface macro-hardness and micro-hardness of the infiltrated layer had been evaluated.The macro-hardness of the surface composite layer decreases with the WC content increasing,and the average macro-hardness is HRC60.The distribution of micro-hardness presents gradient change.The average micro-hardness of the infiltrated layer is about HV1000.展开更多
Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environ...Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.展开更多
The function of solid electrolytes and the composition of solid electrolyte interphase(SEI)are highly significant for inhibiting the growth of Li dendrites.Herein,we report an in-situ interfacial passivation combined ...The function of solid electrolytes and the composition of solid electrolyte interphase(SEI)are highly significant for inhibiting the growth of Li dendrites.Herein,we report an in-situ interfacial passivation combined with self-adaptability strategy to reinforce Li_(0.33)La_(0.557)TiO_(3)(LLTO)-based solid-state batteries.Specifically,a functional SEI enriched with LiF/Li_(3)PO_(4) is formed by in-situ electrochemical conversion,which is greatly beneficial to improving interface compatibility and enhancing ion transport.While the polarized dielectric BaTiO_(3)-polyamic acid(BTO-PAA,BP)film greatly improves the Li-ion transport kinetics and homogenizes the Li deposition.As expected,the resulting electrolyte offers considerable ionic conductivity at room temperature(4.3 x 10~(-4)S cm^(-1))and appreciable electrochemical decomposition voltage(5.23 V)after electrochemical passivation.For Li-LiFePO_(4) batteries,it shows a high specific capacity of 153 mA h g^(-1)at 0.2C after 100 cycles and a long-term durability of 115 mA h g^(-1)at 1.0 C after 800 cycles.Additionally,a stable Li plating/stripping can be achieved for more than 900 h at 0.5 mA cm^(-2).The stabilization mechanisms are elucidated by ex-situ XRD,ex-situ XPS,and ex-situ FTIR techniques,and the corresponding results reveal that the interfacial passivation combined with polarization effect is an effective strategy for improving the electrochemical performance.The present study provides a deeper insight into the dynamic adjustment of electrode-electrolyte interfacial for solid-state lithium batteries.展开更多
In-situ composites are multiphase materials where the reinforcing phase is synthesized by a chemical reaction. The reinforcement generated by this route is very small in size and homogeneously distributed in the matri...In-situ composites are multiphase materials where the reinforcing phase is synthesized by a chemical reaction. The reinforcement generated by this route is very small in size and homogeneously distributed in the matrix. Adoption of the engineering application of this material requires a systematic study of machinability characteristics. This work is an attempt to understand the machinability behavior of the Al-5Cu-TiB2 in-situ metal matrix composites fabricated by Flux-assisted Synthesis. The focus of this study is to investigate the effect of the cutting speed and feed rate on flank wear, cutting force, and surface roughness. The contribution of this paper is to study the influence of in-situ-formed TiB2 reinforcement on the machinability of Al-5Cu alloy. It was found that the increase in cutting speed increased the flank wear, reduced the cutting force, and minimized the surface roughness. Increase in the feed rate increased the flank wear, cutting force, and surface roughness. A higher reinforcement ratio increased the tool wear, reduced the cutting force, and increased the surface roughness. These findings can provide suitable machining parameters in turning of Al-5Cu-TiB2 in-situ metal matrix composites.展开更多
We describe the synthesis of three-dimensional(3D) multilayer ZnO@Ag/SiO2@Ag nanorod arrays by the physico–chemical method. The surface-enhanced Raman scattering(SERS) performance of the 3D multilayer Zn O@Ag/SiO2@Ag...We describe the synthesis of three-dimensional(3D) multilayer ZnO@Ag/SiO2@Ag nanorod arrays by the physico–chemical method. The surface-enhanced Raman scattering(SERS) performance of the 3D multilayer Zn O@Ag/SiO2@Ag nanorod arrays is studied by varying the thickness of dielectric layer SiO2 and outer-layer noble Ag. The 3D Zn O@Ag/SiO2@Ag nanorod arrays create a huge number of SERS "hot spots" that mainly contribute to the high SERS sensitivity. The great enhancement of SERS results from the electron transfer between ZnO and Ag and different electromagnetic enhancements of Ag nanoparticles(NPs) with different thicknesses. Through the finite-difference time-domain(FDTD) theoretical simulation, the enhancement of SERS signal can be ascribed to a strong electric field enhancement produced in the 3D framework. The simplicity and generality of our method offer great advantages for further understanding the SERS mechanism induced by the surface plasmon resonance(SPR) effect.展开更多
The nature of the native oxides formed on the surface layer of amorphous alloy Ni_(64)P_(20)Fe_(16)has been studied by X-ray photoelectron spectroscopy (XPS)and Auger electron spectroscopy(AES)with depth profiling by ...The nature of the native oxides formed on the surface layer of amorphous alloy Ni_(64)P_(20)Fe_(16)has been studied by X-ray photoelectron spectroscopy (XPS)and Auger electron spectroscopy(AES)with depth profiling by ion bombardment.There are great distinctions in compositions and chemical states between the surface layer and the bulk.The main constituents Ni,P and Fe are lower in the sur- face layer,and they are mostly in oxidized states, whereas C,O and N are enriched in the surface lay- er.The thickness of surface oxide layer is approximately 20 nm,this layer was assumed to be of great significance to various properties of amor- phous alloy Ni_(64)P_(20)Fe_(16),expecially to the chemical and catalytic properties.Experiments proved that transitional element Fe cannot improve oxidation resistance of the amorphous Ni-P system.展开更多
The hazard of Hg ion pollution triggers the motivation to explore a fast, sensitive, and reliable detection method. Here, we design and fabricate novel 36-nm-thick Ag-Au composite layers alternately deposited on three...The hazard of Hg ion pollution triggers the motivation to explore a fast, sensitive, and reliable detection method. Here, we design and fabricate novel 36-nm-thick Ag-Au composite layers alternately deposited on three-dimensional (3D) periodic SiO2 nanogrids as surface-enhanced Raman scattering (SERS) probes. The SERS effects of the probes depend mainly on the positions and intensities of their localized surface plasmon resonance (LSPR) peaks, which is confirmed by the absorption spectra from finite-difference time-domain (FDTD) calculations. By optimizing the structure and material to maximize the intrinsic electric field enhancement based on the design method of 3D periodic SERS probes proposed, high performance of the Ag-Au/SiO2 nanogrid probes is achieved with the stability further enhanced by annealing. The optimized probes show the outstanding stability with only 4.0% SERS intensity change during 10-day storage, the excellent detection uniformity of 5.78% (RSD), the detection limit of 5.0 × 10-12 M (1 ppt), and superior selectivity for Hg ions. The present study renders it possible to realize the rapid and reliable detection of trace heavy metal ions by developing high- performance 3D periodic structure SERS probes by designing novel 3D structure and optimizing plasmonic material.展开更多
Appropriate surface modification or functionalization is prerequisite for the application of inorganic nanoparticles.And surface control between organic and inorganic interface plays an important role in constructing ...Appropriate surface modification or functionalization is prerequisite for the application of inorganic nanoparticles.And surface control between organic and inorganic interface plays an important role in constructing organic-inorganic composites.In-situ polymerization has been extensively studied to improve the compatibility and dispersibility of inorganic nanoparticles,but the polymerized nanoparticles tend to concatenate and form large composites,restricting further applications.Herein,uniform and dense polyacrylic acid(PAA)membranes have been grafted on layered double hydroxide(LDH)nanosheets via an in-situ initiating and terminating radical graft polymerization method.With initiating and terminating on the same particle,the size,morphology and density of grafted PAA onto the surface of LDHs can be controlled by adjusting the ratio of initiated sites to terminated sites,the amount of redox initiator or monomer.As a result,with only 17.33%organic grafting ratio,PAA@LDHs with largely improved compatibility can be monodispersed in polyethylene(PE)and polyvinyl chloride(PVC)matrices,which is determined by a fluorescence microscope technique.展开更多
Self-lubricating composites(SLCs)are widely used in the fields of aerospace and marine,but the conventional NiCr matrix SLCs with sulfide as solid lubricant often suffer from low wear resistance at high temperatures.I...Self-lubricating composites(SLCs)are widely used in the fields of aerospace and marine,but the conventional NiCr matrix SLCs with sulfide as solid lubricant often suffer from low wear resistance at high temperatures.In view of its high affinity with oxygen and also the high oxidation rate,appropriate amount of nano Ti was added to NiCr-WS_(2)composites prepared by spark plasma sintering(SPS)to adjust the oxidation behavior and surface texture.When exposed to high temperature,Ti was preferentially oxidized in comparison to Ni and Cr,resulting in abundant TiO_(2)protrusions and microdimples on the surface,i.e.in situ surface texturing.Besides,TiO_(2)was of high chemical activity and readily to react with other oxide debris during high temperature sliding process to form compounds of NiTiO_(3)and CrTi_(2)O_(5).The high chemical activity of oxide debris that was conducive to sintering,combining with the special surface texture that stores as many wear debris as possible,promoted the rapid formation of a protective glaze layer on the sliding surface.The NiCr-WS_(2)-Ti composite exhibited low friction coefficient but high wear resistance at elevated temperatures.Especially at 800℃,it presented a wear rate of as low as(2.1±0.3)×10^(-5)mm^3N-1m^(-1),accounting for only 2.7%of that of NiCr-WS_(2)composite.展开更多
A review of our experience in range of electron spectroscopy of the physical vapor-phase deposition and growth of single- and multilayer nanostructures with atomic scale interfaces is presented. The foundation of an i...A review of our experience in range of electron spectroscopy of the physical vapor-phase deposition and growth of single- and multilayer nanostructures with atomic scale interfaces is presented. The foundation of an innovative methodology for the combined AES-EELS analysis of layered nanostructures is developed. The methodology includes: 1) determination of the composition, thickness, and the mechanism of phase transitions in nanocoatings under the probing depth most appropriated for the range of film thickness 1 - 10 ML;2) quantitative iteration Auger-analysis of the composition, thickness and growth mechanism of nanocoating;3) structural and phase analysis of nanocoatings with use of the analysis of position, shape and energy of the plasmon EELS peak and with subtracting the contribution from the substrate;4) analysis of phase transitions with use of the shift of the plasmon Auger-satellite and 5) non-destructive profiling of the composition of nanocoatings over depth with use of a dependence of the intensity and energy of EELS peaks on the value of the primary electron energy.展开更多
基金Funded by"Xi-Bu-Zhi-Guang" Foundation of Chinese Academy of Sciences(No.XBZG-2007-5)Gansu Natural Science Foundation of China(No.0806RJYA004)Outstanding Youngth of Lanzhou University of Technology (No.Q200910)
文摘The surface infiltrated composite (Ni/WC) layers on gray iron substrate were fabricated through a vacuum infiltration casting technique (VICT) using Ni-based composite powder with different WC particles content as raw materials.The microstructures of surface infiltrated composite layer,the interface structures between surface composite layer and the substrate,the changes of macro-hardness with the increasing of WC content and the micro-hardness distribution are investigated.The infiltrated composite layer includes a surface composite layer and a transition layer,and the thickness of the transition layer decreases with the increasing content of WC.The thickness of transition layer with 20%WC content in the surface infiltrated composite layer was 170 μm which was the thickest for all transition layers with different WC content.The surface composite layer was mainly composed of WC,W2C,FeB and NiB,along with Ni-Cr-Fe,Ni (Cr) solid solution,Ni (Si) solid solution and Ni (Fe) solid solution.The transition layer was composed of Ni (Cr) solid solution,Ni (Fe) solid solution,Ni (Si) solid solution,Fe (Ni) solid solution and eutectic.The surface macro-hardness and micro-hardness of the infiltrated layer had been evaluated.The macro-hardness of the surface composite layer decreases with the WC content increasing,and the average macro-hardness is HRC60.The distribution of micro-hardness presents gradient change.The average micro-hardness of the infiltrated layer is about HV1000.
文摘Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.
基金financially supported by the National Natural Science Foundation of China (51971080)the Shenzhen Bureau of Science,Technology and Innovation Commission (GXWD20201230155427003-20200730151200003 and JSGG20200914113601003)。
文摘The function of solid electrolytes and the composition of solid electrolyte interphase(SEI)are highly significant for inhibiting the growth of Li dendrites.Herein,we report an in-situ interfacial passivation combined with self-adaptability strategy to reinforce Li_(0.33)La_(0.557)TiO_(3)(LLTO)-based solid-state batteries.Specifically,a functional SEI enriched with LiF/Li_(3)PO_(4) is formed by in-situ electrochemical conversion,which is greatly beneficial to improving interface compatibility and enhancing ion transport.While the polarized dielectric BaTiO_(3)-polyamic acid(BTO-PAA,BP)film greatly improves the Li-ion transport kinetics and homogenizes the Li deposition.As expected,the resulting electrolyte offers considerable ionic conductivity at room temperature(4.3 x 10~(-4)S cm^(-1))and appreciable electrochemical decomposition voltage(5.23 V)after electrochemical passivation.For Li-LiFePO_(4) batteries,it shows a high specific capacity of 153 mA h g^(-1)at 0.2C after 100 cycles and a long-term durability of 115 mA h g^(-1)at 1.0 C after 800 cycles.Additionally,a stable Li plating/stripping can be achieved for more than 900 h at 0.5 mA cm^(-2).The stabilization mechanisms are elucidated by ex-situ XRD,ex-situ XPS,and ex-situ FTIR techniques,and the corresponding results reveal that the interfacial passivation combined with polarization effect is an effective strategy for improving the electrochemical performance.The present study provides a deeper insight into the dynamic adjustment of electrode-electrolyte interfacial for solid-state lithium batteries.
文摘In-situ composites are multiphase materials where the reinforcing phase is synthesized by a chemical reaction. The reinforcement generated by this route is very small in size and homogeneously distributed in the matrix. Adoption of the engineering application of this material requires a systematic study of machinability characteristics. This work is an attempt to understand the machinability behavior of the Al-5Cu-TiB2 in-situ metal matrix composites fabricated by Flux-assisted Synthesis. The focus of this study is to investigate the effect of the cutting speed and feed rate on flank wear, cutting force, and surface roughness. The contribution of this paper is to study the influence of in-situ-formed TiB2 reinforcement on the machinability of Al-5Cu alloy. It was found that the increase in cutting speed increased the flank wear, reduced the cutting force, and minimized the surface roughness. Increase in the feed rate increased the flank wear, cutting force, and surface roughness. A higher reinforcement ratio increased the tool wear, reduced the cutting force, and increased the surface roughness. These findings can provide suitable machining parameters in turning of Al-5Cu-TiB2 in-situ metal matrix composites.
基金Project supported by the Fund from the Science and Technology Department of Jilin Province,China(Grant No.20170520108JH)the Beihua University Youth Nurtural Fund,China(Grant No.2017QNJJL15)+1 种基金the Beihua University PhD Research Start-up Fund,China(Grant No.202116140)the Undergraduate Innovation Project,China(Grant No.220718100)
文摘We describe the synthesis of three-dimensional(3D) multilayer ZnO@Ag/SiO2@Ag nanorod arrays by the physico–chemical method. The surface-enhanced Raman scattering(SERS) performance of the 3D multilayer Zn O@Ag/SiO2@Ag nanorod arrays is studied by varying the thickness of dielectric layer SiO2 and outer-layer noble Ag. The 3D Zn O@Ag/SiO2@Ag nanorod arrays create a huge number of SERS "hot spots" that mainly contribute to the high SERS sensitivity. The great enhancement of SERS results from the electron transfer between ZnO and Ag and different electromagnetic enhancements of Ag nanoparticles(NPs) with different thicknesses. Through the finite-difference time-domain(FDTD) theoretical simulation, the enhancement of SERS signal can be ascribed to a strong electric field enhancement produced in the 3D framework. The simplicity and generality of our method offer great advantages for further understanding the SERS mechanism induced by the surface plasmon resonance(SPR) effect.
文摘The nature of the native oxides formed on the surface layer of amorphous alloy Ni_(64)P_(20)Fe_(16)has been studied by X-ray photoelectron spectroscopy (XPS)and Auger electron spectroscopy(AES)with depth profiling by ion bombardment.There are great distinctions in compositions and chemical states between the surface layer and the bulk.The main constituents Ni,P and Fe are lower in the sur- face layer,and they are mostly in oxidized states, whereas C,O and N are enriched in the surface lay- er.The thickness of surface oxide layer is approximately 20 nm,this layer was assumed to be of great significance to various properties of amor- phous alloy Ni_(64)P_(20)Fe_(16),expecially to the chemical and catalytic properties.Experiments proved that transitional element Fe cannot improve oxidation resistance of the amorphous Ni-P system.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0207104)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA09040101)+2 种基金the National Natural Science Foundation of China(Grant No.Y6061111JJ)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2015030)the Key Technology Talent Program of Chinese Academy of Sciences(Grant Nos.Y8482911ZX and Y7602921ZX)
文摘The hazard of Hg ion pollution triggers the motivation to explore a fast, sensitive, and reliable detection method. Here, we design and fabricate novel 36-nm-thick Ag-Au composite layers alternately deposited on three-dimensional (3D) periodic SiO2 nanogrids as surface-enhanced Raman scattering (SERS) probes. The SERS effects of the probes depend mainly on the positions and intensities of their localized surface plasmon resonance (LSPR) peaks, which is confirmed by the absorption spectra from finite-difference time-domain (FDTD) calculations. By optimizing the structure and material to maximize the intrinsic electric field enhancement based on the design method of 3D periodic SERS probes proposed, high performance of the Ag-Au/SiO2 nanogrid probes is achieved with the stability further enhanced by annealing. The optimized probes show the outstanding stability with only 4.0% SERS intensity change during 10-day storage, the excellent detection uniformity of 5.78% (RSD), the detection limit of 5.0 × 10-12 M (1 ppt), and superior selectivity for Hg ions. The present study renders it possible to realize the rapid and reliable detection of trace heavy metal ions by developing high- performance 3D periodic structure SERS probes by designing novel 3D structure and optimizing plasmonic material.
基金supported by the National Natural Science Foundation of China(Nos.21776018,21627813,U170760003,21521005,and 21905014)the Qinghai Provincial Major Science and Technology Special Project(No.2020-GX-A1)the Key R&D Program of Gansu Province(No.19YF3GA003).
文摘Appropriate surface modification or functionalization is prerequisite for the application of inorganic nanoparticles.And surface control between organic and inorganic interface plays an important role in constructing organic-inorganic composites.In-situ polymerization has been extensively studied to improve the compatibility and dispersibility of inorganic nanoparticles,but the polymerized nanoparticles tend to concatenate and form large composites,restricting further applications.Herein,uniform and dense polyacrylic acid(PAA)membranes have been grafted on layered double hydroxide(LDH)nanosheets via an in-situ initiating and terminating radical graft polymerization method.With initiating and terminating on the same particle,the size,morphology and density of grafted PAA onto the surface of LDHs can be controlled by adjusting the ratio of initiated sites to terminated sites,the amount of redox initiator or monomer.As a result,with only 17.33%organic grafting ratio,PAA@LDHs with largely improved compatibility can be monodispersed in polyethylene(PE)and polyvinyl chloride(PVC)matrices,which is determined by a fluorescence microscope technique.
基金financially supported by the National Natural Science Foundation of China(No.51871051)。
文摘Self-lubricating composites(SLCs)are widely used in the fields of aerospace and marine,but the conventional NiCr matrix SLCs with sulfide as solid lubricant often suffer from low wear resistance at high temperatures.In view of its high affinity with oxygen and also the high oxidation rate,appropriate amount of nano Ti was added to NiCr-WS_(2)composites prepared by spark plasma sintering(SPS)to adjust the oxidation behavior and surface texture.When exposed to high temperature,Ti was preferentially oxidized in comparison to Ni and Cr,resulting in abundant TiO_(2)protrusions and microdimples on the surface,i.e.in situ surface texturing.Besides,TiO_(2)was of high chemical activity and readily to react with other oxide debris during high temperature sliding process to form compounds of NiTiO_(3)and CrTi_(2)O_(5).The high chemical activity of oxide debris that was conducive to sintering,combining with the special surface texture that stores as many wear debris as possible,promoted the rapid formation of a protective glaze layer on the sliding surface.The NiCr-WS_(2)-Ti composite exhibited low friction coefficient but high wear resistance at elevated temperatures.Especially at 800℃,it presented a wear rate of as low as(2.1±0.3)×10^(-5)mm^3N-1m^(-1),accounting for only 2.7%of that of NiCr-WS_(2)composite.
文摘A review of our experience in range of electron spectroscopy of the physical vapor-phase deposition and growth of single- and multilayer nanostructures with atomic scale interfaces is presented. The foundation of an innovative methodology for the combined AES-EELS analysis of layered nanostructures is developed. The methodology includes: 1) determination of the composition, thickness, and the mechanism of phase transitions in nanocoatings under the probing depth most appropriated for the range of film thickness 1 - 10 ML;2) quantitative iteration Auger-analysis of the composition, thickness and growth mechanism of nanocoating;3) structural and phase analysis of nanocoatings with use of the analysis of position, shape and energy of the plasmon EELS peak and with subtracting the contribution from the substrate;4) analysis of phase transitions with use of the shift of the plasmon Auger-satellite and 5) non-destructive profiling of the composition of nanocoatings over depth with use of a dependence of the intensity and energy of EELS peaks on the value of the primary electron energy.