The change of conductivity and transparency of silver nanowire （AgNW） films by adding silver nano-particles （AgNPs） onto their surface is studied. The results show that the conductivity of the AgNW film is greatly...The change of conductivity and transparency of silver nanowire （AgNW） films by adding silver nano-particles （AgNPs） onto their surface is studied. The results show that the conductivity of the AgNW film is greatly improved with its sheet resistance reduced about 78. 7% to 51.9Ω/sq, and there is no obvious reduction of the transmittance. Further studies show that there is a self-assembling process pushing the AgNPs to concentrate at the intersecting points between AgNWs to weld them, which would reduce the intersection resistance between the AgNWs. This self-assembling behavior is led by the surface interactivities among the dispersing liquid of AgNPs, the surface of the substrate and AgNWs when the dispersing liquid is drying.展开更多
In this paper, a novel method of producing nanoparticles at low temperatures using hydrogen bombardment of thin films, deposited on glass substrates, is introduced. Silver nanoparticles were obtained by this method in...In this paper, a novel method of producing nanoparticles at low temperatures using hydrogen bombardment of thin films, deposited on glass substrates, is introduced. Silver nanoparticles were obtained by this method in our Plasma Enhanced Chemical Vapor Deposition system. Optical and morphological characteristics of these nanoparticles were extensively studied for various conditions of plasma treatment, such as plasma power density, temperature, duration of hydrogen bombardment, thickness of the initial thin metallic film etc. In addition, Ag-Cu alloy nanoparticles on glass substrates were also achieved. The process of nanoparticle formation in this method shows that several kinds of metals and semiconductors nanoparticles can be obtained using this approach. Scanning Electron Microscopy, Atomic Force Microscopy and Transmission Electron Microscopy were used to analyze the nanostructures.展开更多
The flotation separation of argentite from sphalerite using ammonium dibutyl dithiophosphate(ADD)was studied.Molecular simulation(MS)calculation shows that ADD is chemisorbed on argentite and sphalerite surface in the...The flotation separation of argentite from sphalerite using ammonium dibutyl dithiophosphate(ADD)was studied.Molecular simulation(MS)calculation shows that ADD is chemisorbed on argentite and sphalerite surface in the form of S—P bond.The ADD adsorption on argentite and sphalerite surface in Ag^(+)system was revealed by ICP,Zeta potential and XPS analyses.It is shown that the dissolved Ag^(+)from argentite surface can be absorbed on sphalerite surface in the form of silver hydroxide,and AgOH hydrophilic colloid prevents the adsorption of ADD on sphalerite surface.The ADD adsorption on argentite and sphalerite surface in the pulp containing silver and zinc ions was revealed by adsorption capacity and surface wettability analyses.It is shown that the combined Zn(OH)_(2) and AgOH hydrophilic colloid leads to greater ADD adsorption capacity on argentite surface and stronger surface hydrophobicity than sphalerite.Flotation tests demonstrate that ADD enables efficient separation of argentite from sphalerite in the pulp containing silver and zinc ions.展开更多
To improve the surface corrosion resistance of the alumina films fabricated by micro-arc oxidation （MAO）,Al2O3 coatings at different current densities （5,7 and 10 A/dm 2） were produced on aluminum alloys by adding...To improve the surface corrosion resistance of the alumina films fabricated by micro-arc oxidation （MAO）,Al2O3 coatings at different current densities （5,7 and 10 A/dm 2） were produced on aluminum alloys by adding SiC nano-particles into electrolyte during MAO process.The morphology and phase composition of the coatings were investigated by scanning electron microscopy （SEM） and X-ray diffraction （XRD）,respectively.Furthermore,the corrosion performance of the coatings was evaluated via a three-electrode system in a 3.5 wt pct NaCl solution.From the obtained morphology of alumina coatings,it was believed that the Al2O3 coatings embedded with SiC nano-particles were formed.The electrochemical impedance spectroscopy （EIS） plots and potentiodynamic polarization plots of the Al2O3 coatings with and without SiC nano-particles at different current densities reveal that the Al2O3 coatings with SiC nano-particles formed at 10 A/dm 2 showed the better corrosion resistance than the other coatings produced at 5 and 7 A/dm 2.展开更多
Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites.However,few studies were reported on its applica...Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites.However,few studies were reported on its application in the bond coat of duplex structure thermal barrier coating(TBC).Three kinds of NiCoCrAlY coatings strengthened by different nano-particles with the same addition(1%,mass fraction)were prepared by the laser cladding technique on Ni-based superalloy substrates,aiming to study the effects of the nano-particles on microstructure and oxidation resistance of NiCoCrAlY coatings(the bond coat of the duplex structure thermal barrier coatings).Scanning electron microscope(SEM),X-ray diffractometer(XRD)and thermogravimetry were employed to investigate their morphologies,phases and cyclic oxidation behaviors in atmosphere at 1050℃,compared with the coating without nano-particles.With the addition of nano-particles,the growth pattern of the grains at the interface changed from epitaxial growth to non-epitaxial growth or part-epitaxial growth;slender dendrites were broken and cellularized;cracks and pores were restrained;and the oxidation weight-gain and the stripping resistance of the oxide scale were improved as well.Among the three kinds of nano-particles,the SiC nano-particles showed the most improvement on microstructure,while the CeO2 nano-particles were insufficient,but its effects on the oxidation resistance are the same as those of the SiC nano-particles.Based on the discussions of the influence mechanism,it is believed that CeO2 nano-particles would show better improvement than SiC nano-particles if the proper amount is added and the proper preparation technique of micro-nanometer composite powders is adopted,with the synergistic action of nanometer effect and reactive element effect.展开更多
Nd-Fe-B permanent magnets with a small amount of Cu nano-particles doping have been prepared by con-ventional sintered method. Effects of Cu content on magnetic properties, corrosion resistance, and oxidation properti...Nd-Fe-B permanent magnets with a small amount of Cu nano-particles doping have been prepared by con-ventional sintered method. Effects of Cu content on magnetic properties, corrosion resistance, and oxidation properties of the magnets have been studied. It shows that the coercivity rises gradually, while the remanence decreases simultaneously with increasing Cu doping amount. Microstructure observation reveals that Cu ele- ment enriches mainly the Nd-rich phase. Autoclave test results show that the corrosion rate of the magnets decreases with increasing Cu content. After oxidation, the maximum energy product loss of the magnets with 0 and 0.2 wt% Cu nano-particles doping are 6.13% and 0.g9%, respectively. Therefore, it is concluded that Cu nano-particles doping is a promising way to enhance the coercivity and corrosion resistance of sintered Nd-Fe-B magnets.展开更多
An effective procedure for constructing a DNA biosensor is developed based on covalent immobilization of NH2 labeled,single strand DNA（NH2-ssDNA） onto a self-assembled diazo-thiourea and gold nanoparticles modified ...An effective procedure for constructing a DNA biosensor is developed based on covalent immobilization of NH2 labeled,single strand DNA（NH2-ssDNA） onto a self-assembled diazo-thiourea and gold nanoparticles modified Au electrode（diazo-thiourea/GNM/Au）.Gold nano-particles expand the electrode surface area and increase the amount of immobilized thiourea and single stranded DNA（ssDNA） onto the electrode surface.Diazo-thiourea film provides a surface with high conductibility for electron transfer and a bed for the covalent coupling of NH2-ssDNA onto the electrode surface.The immobilization and hybridization of the probe DNA on the modified electrode is studied by differential pulse voltammetry（DPV） using methylene blue（MB） as a well-known electrochemical hybridization indicator.The linear range for the determination of complementary target ssDNA is from 9.5（±0.1） × 10^-13 mol/L to1.2（±0.2） x 10^-9 mol/L with a detection limit of 1.2（±0.1） 〉 10^-13 mol/L.展开更多
In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, ...In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, the surface tension of Li Br aqueous solution with 1-octanol was measured and then the comparison between the measured results and previous experimental results was given to verify the measuring accuracy. Some new additives, such as cationic surfactants cetyltrimethyl ammonium chloride(CTAC), and cetyltrimethyl ammonium bromide(CTAB) were chosen in the experiments. The experimental results show that CTAC and CTAB can obviously reduce the surface tension of Li Br aqueous solution/ammonia. In addition, it is found that nano-particles cannot remarkably decrease the surface tension of Li Br aqueous solution/ammonia. However, the mixed addition of additives and nano-particles can remarkably affect the surface tension of Li Br aqueous solution/ammonia. That is to say, additives play more important role in reducing the surface tension of Li Br aqueous solution/ammonia. But nano-particles may enhance the heat transfer in the absorption refrigeration process.展开更多
Ni-W-P matrix composite coatings reinforced by CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by double pulse electrodeposition and the deposition mechanism was discussed.The results showed ...Ni-W-P matrix composite coatings reinforced by CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by double pulse electrodeposition and the deposition mechanism was discussed.The results showed that the composite coatings with amorphous structure were obtained as-deposited.The initial growth behavior had alternatives and the nucleation was inhomogeneous because of obvious composition fluctuation.With the pulse deposition time increasing,some pearlite microstructures of the substrate were covered by some deposits and the composition fluctuation disappeared.Forward pulse currents promoted to form a great number of atomic beams composed of Ni,W and P atoms or CeO2 and SiO2 nano-particles as the core,which inhabited the growth of atomic beams.Reverse pulse currents eliminated concentration polarization and dissolved some surface boss of atomic beams.The solution of W and P atoms within Ni grains and embedding of CeO2 and SiO2 nano-particles within Ni-W-P matrix metal made atomic arrangement disordered.Finally,the atomic beams grew to amorphous small particles.展开更多
Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on...Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on microstructures and properties of Ni-W-P/CeO2-SiO2 composites was studied,and the characteristics were assessed by chemical compositions,element distribution,surface morphologies,deposition rate and microhardness.The results indicate that when SiO2 concentration in bath is controlled at 20 g/L,the composites possess the fastest deposition rate,the highest microhardness,compact microstructures,smaller crystallite sizes and uniform distribution of W,P,Ce and Si within Ni-W-P matrix metal.Increasing SiO2 concentration in bath from 10 to 20 g/L leads to the refinement in grain size and the inhomogeneity of microstructures.While when SiO2 concentration is increased to 30 g/L,the crystallite sizes increase again and some bosses with nodulation shape appear on the surface of composites.展开更多
The modified Fe3O4 nanoparticles with the extracted pectin from the cell wall of Azolla filicoloides（FNEP） can remove methyl orange as a watersoluble azo dye from waste water better than Azolla and the extracted pec...The modified Fe3O4 nanoparticles with the extracted pectin from the cell wall of Azolla filicoloides（FNEP） can remove methyl orange as a watersoluble azo dye from waste water better than Azolla and the extracted pectin from Azolla（EPA）,alone.It could be due to more crowding the main functional groups of uptake after binding pectin with nanoparticles.Thermodynamic studies showed that adsorption equilibrium constant（KL） and maximum adsorption capacities（Q（max）） were increased with decreasing temperature（exothermic）.The maximum uptake capacity（Q（max）） of dye by FNEP in a batch reactor was 0.533,0.498 and 0.446 mmol/g at 5,25 and 50℃,respectively.The enthalpy change（△H） and entropy change（△S） were 15.31 kJ/mol and 0.02434 kJ/mol K,respectively.展开更多
By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanop...By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM） and vibrating sample magnetometer （VSM）, respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation （10 kGy） is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation （10 kGy） are mainly in small cubic shape and the size uniformity of these particles is good.展开更多
ZnS nano-particles with average sizes of 10 nm and 5 nm were fabricated by sol-gel method, and their pressure-induced phase transformations were in-situ examined in a diamond anvil cell by energy dispersive X-ray diff...ZnS nano-particles with average sizes of 10 nm and 5 nm were fabricated by sol-gel method, and their pressure-induced phase transformations were in-situ examined in a diamond anvil cell by energy dispersive X-ray diffraction （EDXD） from ambient pressure to 35.0 GPa. From the obtained interplanar spacing data,the volume compression ratios were derived at different pressures, and then the bulk modulus and its pressure derivative were obtained by fitting to the Murnaghan equation. It is found that both ZnS nano-particles initially in the zinc-blende phase transformed to cubic NaCl structure in the presence of pressure and the transition was reversible when the pressure was released. Moreover, it is suggested that a smaller particle size will induce a larger transition pressure.展开更多
Microstructural evolution and strengthening mechanisms of Mg-3Sn-1Ca based alloys with additions of different amounts of Al N nanoparticles were investigated.It was found that with increasing the amount of AlN nano-pa...Microstructural evolution and strengthening mechanisms of Mg-3Sn-1Ca based alloys with additions of different amounts of Al N nanoparticles were investigated.It was found that with increasing the amount of AlN nano-particles the grain size decreases obviously.The existence of AlN nano-particles could refine the primary crystal phases CaMgSn,which provided more heterogeneous nucleation sites for the formation of magnesium.Moreover,such nano-particles could also restrict the grain growth during solidification.After adding AlN nano-particles,both the tensile properties at room temperature and high temperature 250℃and the hardness are largely improved.The improvement of strength is attributed to grain refinement and second phase refinement.展开更多
Composites formed by adding nano-scale particles to a polymer matrix results in improving electrical, mechanical, and thermal properties of the composite. Good tribological properties can be obtained for polymers fill...Composites formed by adding nano-scale particles to a polymer matrix results in improving electrical, mechanical, and thermal properties of the composite. Good tribological properties can be obtained for polymers filled with nano-scale fillers compared to that filled with micro-scale particles. The friction and wear resistance of these composites is found to increase with increasing filler concentration. It is also possible to use multi-functional fillers to develop high performance composites which cannot be achieved by using a single filler.展开更多
Ni-W-P composite coatings reinforced by Ce O2 and Si O2 nano-particles on the surface of common carbon steels, were prepared by double pulse electrodeposition. The crystallization course was characterized by phase str...Ni-W-P composite coatings reinforced by Ce O2 and Si O2 nano-particles on the surface of common carbon steels, were prepared by double pulse electrodeposition. The crystallization course was characterized by phase structures, crystallinity, grain sizes and microstructures. The results indicate that as-deposited composite coating is amorphous. Whereas it turns into the crystalline structure with 98.25% crystallinity, and Ni3 P, Ni2 P and Ni5P2 alloy phases precipitate from structures at 400 °C. Thereafter, Ni2 P and Ni5P2 metastable alloy phases turn into Ni3 P stable alloy phase at 500 °C. The crystallization course of the composite coating has finished when being heat-treated at 700 °C. The average sizes of Ni grains increase with the rise of heat treatment temperature from400 °C to 700 °C. Ce O2 and Si O2 nano-particles deposited into Ni-W-P alloys can delay the crystallization course and habit the growth of alloy phases.展开更多
Molybdenum disulfide(MoS_(2))has shown significant promise as an economic hydrogen evolution reaction(HER)catalyst for hydrogen generation,but its catalytic performance is still lower than noble metalbased catalysists...Molybdenum disulfide(MoS_(2))has shown significant promise as an economic hydrogen evolution reaction(HER)catalyst for hydrogen generation,but its catalytic performance is still lower than noble metalbased catalysists.Herein,a silver nanoparticles(Ag NPs)-decorated 1T/2H phase layered MoS_(2) electrocatalyst grown on titanium dioxide nanorod arrays(Ag NPs/1T(2H)MoS_(2)/TNRs)was prepared through acid-tunable ammonium ion intercalation.Taking advantage of MoS_(2) layered structure and crystal phase controllability,as-prepared Ag NPs/1T(2H)MoS_(2)/TNRs exhibited ultrahigh HER activity.As-proposed strategy combines facile hydrogen desorption(Ag NPs)with efficient hydrogen adsorption(1T/2H MoS_(2))effectively circumventes the kinetic limitation of hydrogen desorption by 1T/2H MoS_(2).The as-prepared Ag NPs/1T(2H)MoS_(2)/TNRs electrocatalyst exhibited excellent HER activity in 0.5 mol/L H2SO4 with low overpotential(118 mV vs.reversible hydrogen electrode(RHE))and small Tafel slope(38.61 mV/dec).The overpotential exhibts no obvious attenuation after 10 h of constant current flow.First-principles calculation demonstrates that as-prepared 1T/2H MoS_(2) exhibit a large capacity to store protons.These protons can be subsequently transferred to Ag NPs,which significantly increases the hydrogen coverage on the surface of Ag NPs in HER process and thus change the rate-determining step of HER on Ag NPs from water dissociation to hydrogen recombination.This study provides a unique strategy to improve the catalytic activity and stability for MoS_(2)-based electrocatalyst.展开更多
Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave.The particles and silicon are heated by the irradiation and they will expand differently due to their different exp...Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave.The particles and silicon are heated by the irradiation and they will expand differently due to their different expansion coefficients,making the particles easier to be removed.Laser plasma can ionize and even vaporize particles more significantly than an incident laser and,therefore,it can remove the particles more efficiently.The laser plasma shock wave plays a dominant role in removing particles,which is attributed to its strong burst force.The pressure of the laser plasma shock wave is determined by the laser pulse energy and the gap between the focus of laser and substrate surface.In order to obtain the working conditions for particle removal,the removal mechanism,as well as the temporal and spatial characteristics of velocity,propagation distance and pressure of shock wave have been researched.On the basis of our results,the conditions for nano-particle removal are achieved.展开更多
Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made ...Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We found that the surface resistivity measurements on PVA films were readily implemented.展开更多
Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial property.However,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are...Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial property.However,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water pollution.In this work,Ag NPs(31.2 nm in diameter)were prepared using the extract of straw,an agricultural waste,as the reducing and stabilizing agent.Experimental analysis revealed that the straw extract contained lignin,the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag NPs.The surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their aggregation.After the prepared Ag NPs were added to the precursor solution of acrylamide,free radical polymerization was triggered without the need for extra heating or light irradiation,resulting in the rapid formation of an Ag NP-polyacrylamide composite hydrogel.The inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag NPs.The prepared hydrogel may have potential applications in the fabrication of biomedical materials,such as antibacterial dressings.展开更多
文摘The change of conductivity and transparency of silver nanowire （AgNW） films by adding silver nano-particles （AgNPs） onto their surface is studied. The results show that the conductivity of the AgNW film is greatly improved with its sheet resistance reduced about 78. 7% to 51.9Ω/sq, and there is no obvious reduction of the transmittance. Further studies show that there is a self-assembling process pushing the AgNPs to concentrate at the intersecting points between AgNWs to weld them, which would reduce the intersection resistance between the AgNWs. This self-assembling behavior is led by the surface interactivities among the dispersing liquid of AgNPs, the surface of the substrate and AgNWs when the dispersing liquid is drying.
文摘In this paper, a novel method of producing nanoparticles at low temperatures using hydrogen bombardment of thin films, deposited on glass substrates, is introduced. Silver nanoparticles were obtained by this method in our Plasma Enhanced Chemical Vapor Deposition system. Optical and morphological characteristics of these nanoparticles were extensively studied for various conditions of plasma treatment, such as plasma power density, temperature, duration of hydrogen bombardment, thickness of the initial thin metallic film etc. In addition, Ag-Cu alloy nanoparticles on glass substrates were also achieved. The process of nanoparticle formation in this method shows that several kinds of metals and semiconductors nanoparticles can be obtained using this approach. Scanning Electron Microscopy, Atomic Force Microscopy and Transmission Electron Microscopy were used to analyze the nanostructures.
基金the support from the National Key Research and Development Program of China (No. 2022YFC2904504)the Science and Technology Research Project of Jiangxi Provincial Department of Education, China (No. GJJ2200864)the Gansu Provincial Key Research and Development Project, China (No. 22YF7GA073)。
文摘The flotation separation of argentite from sphalerite using ammonium dibutyl dithiophosphate(ADD)was studied.Molecular simulation(MS)calculation shows that ADD is chemisorbed on argentite and sphalerite surface in the form of S—P bond.The ADD adsorption on argentite and sphalerite surface in Ag^(+)system was revealed by ICP,Zeta potential and XPS analyses.It is shown that the dissolved Ag^(+)from argentite surface can be absorbed on sphalerite surface in the form of silver hydroxide,and AgOH hydrophilic colloid prevents the adsorption of ADD on sphalerite surface.The ADD adsorption on argentite and sphalerite surface in the pulp containing silver and zinc ions was revealed by adsorption capacity and surface wettability analyses.It is shown that the combined Zn(OH)_(2) and AgOH hydrophilic colloid leads to greater ADD adsorption capacity on argentite surface and stronger surface hydrophobicity than sphalerite.Flotation tests demonstrate that ADD enables efficient separation of argentite from sphalerite in the pulp containing silver and zinc ions.
基金supported by the Ministry of Education of the People's Republic of China (Contract No. 210051)
文摘To improve the surface corrosion resistance of the alumina films fabricated by micro-arc oxidation （MAO）,Al2O3 coatings at different current densities （5,7 and 10 A/dm 2） were produced on aluminum alloys by adding SiC nano-particles into electrolyte during MAO process.The morphology and phase composition of the coatings were investigated by scanning electron microscopy （SEM） and X-ray diffraction （XRD）,respectively.Furthermore,the corrosion performance of the coatings was evaluated via a three-electrode system in a 3.5 wt pct NaCl solution.From the obtained morphology of alumina coatings,it was believed that the Al2O3 coatings embedded with SiC nano-particles were formed.The electrochemical impedance spectroscopy （EIS） plots and potentiodynamic polarization plots of the Al2O3 coatings with and without SiC nano-particles at different current densities reveal that the Al2O3 coatings with SiC nano-particles formed at 10 A/dm 2 showed the better corrosion resistance than the other coatings produced at 5 and 7 A/dm 2.
基金supported by Specialized Research Fund for Doctoral Program of Higher Education of China(Grant No.20060287019)Opening Research Fund of Jiangsu Provincial Key Laboratory of Tribology of China(Grant No.kjsmcx07001)Jiangsu Provincial Graduate Innovation Foundation of China(Grant No.CX08B-039Z)
文摘Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites.However,few studies were reported on its application in the bond coat of duplex structure thermal barrier coating(TBC).Three kinds of NiCoCrAlY coatings strengthened by different nano-particles with the same addition(1%,mass fraction)were prepared by the laser cladding technique on Ni-based superalloy substrates,aiming to study the effects of the nano-particles on microstructure and oxidation resistance of NiCoCrAlY coatings(the bond coat of the duplex structure thermal barrier coatings).Scanning electron microscope(SEM),X-ray diffractometer(XRD)and thermogravimetry were employed to investigate their morphologies,phases and cyclic oxidation behaviors in atmosphere at 1050℃,compared with the coating without nano-particles.With the addition of nano-particles,the growth pattern of the grains at the interface changed from epitaxial growth to non-epitaxial growth or part-epitaxial growth;slender dendrites were broken and cellularized;cracks and pores were restrained;and the oxidation weight-gain and the stripping resistance of the oxide scale were improved as well.Among the three kinds of nano-particles,the SiC nano-particles showed the most improvement on microstructure,while the CeO2 nano-particles were insufficient,but its effects on the oxidation resistance are the same as those of the SiC nano-particles.Based on the discussions of the influence mechanism,it is believed that CeO2 nano-particles would show better improvement than SiC nano-particles if the proper amount is added and the proper preparation technique of micro-nanometer composite powders is adopted,with the synergistic action of nanometer effect and reactive element effect.
基金supported by the National Natural Science Foundation of China (No. 51001002)the Research Fund for the Doctoral Program of Higher Education of China (No. 20091103120024)+2 种基金the National High Technology Research and Development Program of China (No.2012AA063201)the Key Program of Science and Technology Development Project of Beijing Municipal Education Commission (No. KZ201110005007)211 Project of Beijing University of Technology and Rixin Talents of Beijing University of Technology
文摘Nd-Fe-B permanent magnets with a small amount of Cu nano-particles doping have been prepared by con-ventional sintered method. Effects of Cu content on magnetic properties, corrosion resistance, and oxidation properties of the magnets have been studied. It shows that the coercivity rises gradually, while the remanence decreases simultaneously with increasing Cu doping amount. Microstructure observation reveals that Cu ele- ment enriches mainly the Nd-rich phase. Autoclave test results show that the corrosion rate of the magnets decreases with increasing Cu content. After oxidation, the maximum energy product loss of the magnets with 0 and 0.2 wt% Cu nano-particles doping are 6.13% and 0.g9%, respectively. Therefore, it is concluded that Cu nano-particles doping is a promising way to enhance the coercivity and corrosion resistance of sintered Nd-Fe-B magnets.
文摘An effective procedure for constructing a DNA biosensor is developed based on covalent immobilization of NH2 labeled,single strand DNA（NH2-ssDNA） onto a self-assembled diazo-thiourea and gold nanoparticles modified Au electrode（diazo-thiourea/GNM/Au）.Gold nano-particles expand the electrode surface area and increase the amount of immobilized thiourea and single stranded DNA（ssDNA） onto the electrode surface.Diazo-thiourea film provides a surface with high conductibility for electron transfer and a bed for the covalent coupling of NH2-ssDNA onto the electrode surface.The immobilization and hybridization of the probe DNA on the modified electrode is studied by differential pulse voltammetry（DPV） using methylene blue（MB） as a well-known electrochemical hybridization indicator.The linear range for the determination of complementary target ssDNA is from 9.5（±0.1） × 10^-13 mol/L to1.2（±0.2） x 10^-9 mol/L with a detection limit of 1.2（±0.1） 〉 10^-13 mol/L.
基金Project(51206033)supported by the National Natural Science Foundation of ChinaProjects(2011M500652,2013T60354)supported by the China Postdoctoral Science FoundationProject(2011LBH-Z11139)supported by the Heilongjiang Postdoctoral Science Foundation,China
文摘In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, the surface tension of Li Br aqueous solution with 1-octanol was measured and then the comparison between the measured results and previous experimental results was given to verify the measuring accuracy. Some new additives, such as cationic surfactants cetyltrimethyl ammonium chloride(CTAC), and cetyltrimethyl ammonium bromide(CTAB) were chosen in the experiments. The experimental results show that CTAC and CTAB can obviously reduce the surface tension of Li Br aqueous solution/ammonia. In addition, it is found that nano-particles cannot remarkably decrease the surface tension of Li Br aqueous solution/ammonia. However, the mixed addition of additives and nano-particles can remarkably affect the surface tension of Li Br aqueous solution/ammonia. That is to say, additives play more important role in reducing the surface tension of Li Br aqueous solution/ammonia. But nano-particles may enhance the heat transfer in the absorption refrigeration process.
基金Projects supported by the National Natural Science Foundation of China (20806035)Back-up Personnel Foundation of Academic and Technology Leaders of Yunnan Province (2009CI026)+3 种基金Opening Project of Key Laboratory of Inorganic Coating Materials,Chinese Academy of Sciences (KKZ6200927001)Applied Basic Research Plans Program of Yunnan Province (2007E187M)Scientific Research Fund of Yunnan Provincial Education Department (08C0025)Training Foundation for Talents and Analysis and Measurement Foundation of KMUST
文摘Ni-W-P matrix composite coatings reinforced by CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by double pulse electrodeposition and the deposition mechanism was discussed.The results showed that the composite coatings with amorphous structure were obtained as-deposited.The initial growth behavior had alternatives and the nucleation was inhomogeneous because of obvious composition fluctuation.With the pulse deposition time increasing,some pearlite microstructures of the substrate were covered by some deposits and the composition fluctuation disappeared.Forward pulse currents promoted to form a great number of atomic beams composed of Ni,W and P atoms or CeO2 and SiO2 nano-particles as the core,which inhabited the growth of atomic beams.Reverse pulse currents eliminated concentration polarization and dissolved some surface boss of atomic beams.The solution of W and P atoms within Ni grains and embedding of CeO2 and SiO2 nano-particles within Ni-W-P matrix metal made atomic arrangement disordered.Finally,the atomic beams grew to amorphous small particles.
基金Project(20806035) supported by the National Natural Science Foundation of ChinaProject(2009CI026) supported by Back-up Personnel Foundation of Academic and Technology Leaders of Yunnan Province,China+4 种基金Project(KKZ6200927001) supported by Opening Fund of Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences Project(2007E187M) supported by Applied Basic Research Plans of Yunnan Province,ChinaProject(08C0025) supported by Scientific Research Fund of Yunnan Provincial Education Department, China Project(KKZ3200927029) supported by Training Foundation for Talents of Kunming University of Science and Technology,ChinaProject(2008-003) supported by Analysis and Measurement Research Fund of Kunming University of Science and Technology,China
文摘Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on microstructures and properties of Ni-W-P/CeO2-SiO2 composites was studied,and the characteristics were assessed by chemical compositions,element distribution,surface morphologies,deposition rate and microhardness.The results indicate that when SiO2 concentration in bath is controlled at 20 g/L,the composites possess the fastest deposition rate,the highest microhardness,compact microstructures,smaller crystallite sizes and uniform distribution of W,P,Ce and Si within Ni-W-P matrix metal.Increasing SiO2 concentration in bath from 10 to 20 g/L leads to the refinement in grain size and the inhomogeneity of microstructures.While when SiO2 concentration is increased to 30 g/L,the crystallite sizes increase again and some bosses with nodulation shape appear on the surface of composites.
文摘The modified Fe3O4 nanoparticles with the extracted pectin from the cell wall of Azolla filicoloides（FNEP） can remove methyl orange as a watersoluble azo dye from waste water better than Azolla and the extracted pectin from Azolla（EPA）,alone.It could be due to more crowding the main functional groups of uptake after binding pectin with nanoparticles.Thermodynamic studies showed that adsorption equilibrium constant（KL） and maximum adsorption capacities（Q（max）） were increased with decreasing temperature（exothermic）.The maximum uptake capacity（Q（max）） of dye by FNEP in a batch reactor was 0.533,0.498 and 0.446 mmol/g at 5,25 and 50℃,respectively.The enthalpy change（△H） and entropy change（△S） were 15.31 kJ/mol and 0.02434 kJ/mol K,respectively.
基金This work was supported by the Natural Science Foundation of Henan Province under grant No. 0611023900.
文摘By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM） and vibrating sample magnetometer （VSM）, respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation （10 kGy） is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation （10 kGy） are mainly in small cubic shape and the size uniformity of these particles is good.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 10299040）；National Basic Research Priorities Programme of China （Grant No. 2001CB711201）.
文摘ZnS nano-particles with average sizes of 10 nm and 5 nm were fabricated by sol-gel method, and their pressure-induced phase transformations were in-situ examined in a diamond anvil cell by energy dispersive X-ray diffraction （EDXD） from ambient pressure to 35.0 GPa. From the obtained interplanar spacing data,the volume compression ratios were derived at different pressures, and then the bulk modulus and its pressure derivative were obtained by fitting to the Murnaghan equation. It is found that both ZnS nano-particles initially in the zinc-blende phase transformed to cubic NaCl structure in the presence of pressure and the transition was reversible when the pressure was released. Moreover, it is suggested that a smaller particle size will induce a larger transition pressure.
基金financially supported by the Study Abroad Program by the Government of Shandong Province(201802005)Linyi Industrial Technology Research Institute and Shandong Yinguang Yuyuan Light Metal Precise Forming Co.,Ltd。
文摘Microstructural evolution and strengthening mechanisms of Mg-3Sn-1Ca based alloys with additions of different amounts of Al N nanoparticles were investigated.It was found that with increasing the amount of AlN nano-particles the grain size decreases obviously.The existence of AlN nano-particles could refine the primary crystal phases CaMgSn,which provided more heterogeneous nucleation sites for the formation of magnesium.Moreover,such nano-particles could also restrict the grain growth during solidification.After adding AlN nano-particles,both the tensile properties at room temperature and high temperature 250℃and the hardness are largely improved.The improvement of strength is attributed to grain refinement and second phase refinement.
文摘Composites formed by adding nano-scale particles to a polymer matrix results in improving electrical, mechanical, and thermal properties of the composite. Good tribological properties can be obtained for polymers filled with nano-scale fillers compared to that filled with micro-scale particles. The friction and wear resistance of these composites is found to increase with increasing filler concentration. It is also possible to use multi-functional fillers to develop high performance composites which cannot be achieved by using a single filler.
基金Project(20806035)supported by the National Natural Science Foundation of ChinaProject(2009CI026)supported by the Back-up Personnel Foundation of Academic and Technology Leaders of Yunnan Province,ChinaProject(KKZ6200927001)supported by the Opening Fund of Key Laboratory of Inorganic Coating Materials,Chinese Academy of Sciences
文摘Ni-W-P composite coatings reinforced by Ce O2 and Si O2 nano-particles on the surface of common carbon steels, were prepared by double pulse electrodeposition. The crystallization course was characterized by phase structures, crystallinity, grain sizes and microstructures. The results indicate that as-deposited composite coating is amorphous. Whereas it turns into the crystalline structure with 98.25% crystallinity, and Ni3 P, Ni2 P and Ni5P2 alloy phases precipitate from structures at 400 °C. Thereafter, Ni2 P and Ni5P2 metastable alloy phases turn into Ni3 P stable alloy phase at 500 °C. The crystallization course of the composite coating has finished when being heat-treated at 700 °C. The average sizes of Ni grains increase with the rise of heat treatment temperature from400 °C to 700 °C. Ce O2 and Si O2 nano-particles deposited into Ni-W-P alloys can delay the crystallization course and habit the growth of alloy phases.
基金supported by the National Natural Science Foundation of China(No.52270078)the Royal Society IEC\NSFC\211201-International Exchanges 2021 Cost Share(NSFC).
文摘Molybdenum disulfide(MoS_(2))has shown significant promise as an economic hydrogen evolution reaction(HER)catalyst for hydrogen generation,but its catalytic performance is still lower than noble metalbased catalysists.Herein,a silver nanoparticles(Ag NPs)-decorated 1T/2H phase layered MoS_(2) electrocatalyst grown on titanium dioxide nanorod arrays(Ag NPs/1T(2H)MoS_(2)/TNRs)was prepared through acid-tunable ammonium ion intercalation.Taking advantage of MoS_(2) layered structure and crystal phase controllability,as-prepared Ag NPs/1T(2H)MoS_(2)/TNRs exhibited ultrahigh HER activity.As-proposed strategy combines facile hydrogen desorption(Ag NPs)with efficient hydrogen adsorption(1T/2H MoS_(2))effectively circumventes the kinetic limitation of hydrogen desorption by 1T/2H MoS_(2).The as-prepared Ag NPs/1T(2H)MoS_(2)/TNRs electrocatalyst exhibited excellent HER activity in 0.5 mol/L H2SO4 with low overpotential(118 mV vs.reversible hydrogen electrode(RHE))and small Tafel slope(38.61 mV/dec).The overpotential exhibts no obvious attenuation after 10 h of constant current flow.First-principles calculation demonstrates that as-prepared 1T/2H MoS_(2) exhibit a large capacity to store protons.These protons can be subsequently transferred to Ag NPs,which significantly increases the hydrogen coverage on the surface of Ag NPs in HER process and thus change the rate-determining step of HER on Ag NPs from water dissociation to hydrogen recombination.This study provides a unique strategy to improve the catalytic activity and stability for MoS_(2)-based electrocatalyst.
基金Project supported by the National Natural Science Foundation of China(Grant No.11574221)
文摘Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave.The particles and silicon are heated by the irradiation and they will expand differently due to their different expansion coefficients,making the particles easier to be removed.Laser plasma can ionize and even vaporize particles more significantly than an incident laser and,therefore,it can remove the particles more efficiently.The laser plasma shock wave plays a dominant role in removing particles,which is attributed to its strong burst force.The pressure of the laser plasma shock wave is determined by the laser pulse energy and the gap between the focus of laser and substrate surface.In order to obtain the working conditions for particle removal,the removal mechanism,as well as the temporal and spatial characteristics of velocity,propagation distance and pressure of shock wave have been researched.On the basis of our results,the conditions for nano-particle removal are achieved.
文摘Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We found that the surface resistivity measurements on PVA films were readily implemented.
基金financially supported by the National Natural Science Foundation of China(No.52203209)the State Key Laboratory of Solid Waste Reuse for Building Materials,China(No.SWR-2022-009)the Fundamental Research Funds for the Central Universities,China(No.FRF-IDRY22-012)。
文摘Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial property.However,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water pollution.In this work,Ag NPs(31.2 nm in diameter)were prepared using the extract of straw,an agricultural waste,as the reducing and stabilizing agent.Experimental analysis revealed that the straw extract contained lignin,the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag NPs.The surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their aggregation.After the prepared Ag NPs were added to the precursor solution of acrylamide,free radical polymerization was triggered without the need for extra heating or light irradiation,resulting in the rapid formation of an Ag NP-polyacrylamide composite hydrogel.The inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag NPs.The prepared hydrogel may have potential applications in the fabrication of biomedical materials,such as antibacterial dressings.
