The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces...The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces were measured directly by atomic force microscopy (AFM) based on the bending mode of the nominal constant compliance regime in AFM force curve in the present study. Surface and solid-liquid interfacial energies were calculated to explain the forming mechanism of the hydration film and atomic force microscopy data. The results show that there are significant differences in the structure and thickness of hydration films on coal and mica surfaces. Hydration film formed on mica surface with the thickness of 22.5 nm. In contrast, the bend was not detected in the nominal constant compliance regime. The van der Waals and polar interactions between both mica and coal and water molecules are characterized by an attractive effect, while the polar attractive free energy between water and mica (-87.36 mN/m) is significantly larger than that between water and coal (-32.89 mN/m), which leads to a thicker and firmer hydration layer on the mica surface. The interfacial interaction free energy of the coal/water/bubble is greater than that of mica. The polar attractive force is large enough to overcome the repulsive van der Waals force and the low energy barrier of film rupture, achieving coal particle bubble adhesion with a total interfacial free energy of-56.30 mN/m.展开更多
The auto-evolved ultrafine copper powders were synlhesized via a novel electrodeposition route performed by ultrasonic dispersion of the electrolyte. The properties of the samples obtained were characterized by X-ray ...The auto-evolved ultrafine copper powders were synlhesized via a novel electrodeposition route performed by ultrasonic dispersion of the electrolyte. The properties of the samples obtained were characterized by X-ray powder diffractometry （XRD）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM） and laser size distribution analyzer （SL） respectively. The formation mechanisms of the powders and the efficiency of the elctrodeposition were discussed. The results show that the as-prepared powders are high-purity copper nanoparticles with the fcc structure taking a mixture of fishbone-like and irregular shapes When the concentration of Cu^2＋ increases from 0.03 to 0.09 mol/L, the average size of copper particles increases from 0.92 to 1.80 μm, and current efficiency of electrodeposition linearly changes from 66.5% to 91.3%.展开更多
Magnesium oxysulfate （MgSO4·5Mg（OH）2·2H2O） flake powders with an average diameter of 2 ~tm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydr...Magnesium oxysulfate （MgSO4·5Mg（OH）2·2H2O） flake powders with an average diameter of 2 ~tm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydrothermal synthesis process. The composition, morphology and structural features of the hydrothermal products were examined with X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. The experimental results indicate that in the conditions of n（NaOH）/n（MgSO4） of 1.25, the dosage of w（Na3PO4） crystal additives of 1.0% w（MgSO4）, stirring for 5 h at 180 ℃, the morphology of MgSO4·5Mg（OH）2·2H2O products is flaky and laminar, which is a kind of complex magnesium singlecrystal. The recycling of MgSO4 mother liquor was also investigated to make a full use of the materials and reduce disposal. The results prove that there is no adverse effect on the yield and purity of the products.展开更多
FePt granular films were prepared by direct current facing-target magnetron sputtering system onto glass substrates and subsequently in-situ annealed in vacuum. Vibrating sample magnetometer, X-ray diffraction and sca...FePt granular films were prepared by direct current facing-target magnetron sputtering system onto glass substrates and subsequently in-situ annealed in vacuum. Vibrating sample magnetometer, X-ray diffraction and scanning probe microscope were applied to study the magnetic properties, microstructures, morphologies and domain structures of the samples. （FePt）27Ti73 bilayer films were fabricated at various conditions to investigate the effect of Ti on FePt grains. The results show that without Ti matrix layer, FePt films deposited onto the glass substrates are fcc disordered; with addition of Ti matrix layer, FePt/Ti films form a ternary （FePt）27Ti73 alloy possessing fcc and L10 （111） mixed texture. FePt/（FePt）27Ti73 films with perfectly ordered L10（111） structure and unique magnetic properties can be obtained at Ti thickness of 35nm and substrate temperature of 250℃. The maximum coercivity is more than 240kA/m and the squareness ratio is more than 0.9. The obtained results suggest that the granular FePt/（FePt）27Ti73 films can be applicable to ultrahigh-density magnetic recording media.展开更多
Porous and dense TiNi alloys were successfully fabricated by powder metallurgy(P/M) method, and to further improve their surface biocompatibility, surface modification techniques including grind using silicon-carbide(...Porous and dense TiNi alloys were successfully fabricated by powder metallurgy(P/M) method, and to further improve their surface biocompatibility, surface modification techniques including grind using silicon-carbide(SiC) paper, acid etching and alkali treatment were employed to produce either irregularly rough surface or micro-porous surface roughness. X-ray diffractometry(XRD), scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDX) attached to SEM were used to characterize surface structure and the Ca-P coatings. Effects of the above surface treatments on the surface morphology, apatite forming ability were systematically investigated. Results indicate that all the above surface treatments increase the apatite forming ability of TiNi alloys in varying degrees when soaked in simulated body fluid(SBF). More apatite coatings formed on TiNi samples sintered at 1050℃ and 1100℃ due to their high porosity and pure TiNi phase that is beneficial to heterogeneous nucleation. Furthermore, more uniform apatite was fabricated on the sample sintered from the mixture of Ni and Ti powders.展开更多
The wettability,surfactivity and the correlation between wettability and surfactivity of sodium diethylhexylphosphate,sodium diethylhexyl polyoxyethylene phosphate and their complex in NaOH solutions were studied.A co...The wettability,surfactivity and the correlation between wettability and surfactivity of sodium diethylhexylphosphate,sodium diethylhexyl polyoxyethylene phosphate and their complex in NaOH solutions were studied.A complex alkali resistant phosphate surfactant with good permeability was prepared.The wettability of surfactants was investigated by measuring the immersion time,sinking time and capillary effects of nature cotton grey fabric in NaOH solutions.The surfactivity of the surfactants was characterized by measuring the surface tension.The effect of the complex on the surface appearance of cotton grey fabric was also investigated with a scanning electron microscope(SEM) .The results show that all the surfactants exhibit good wettability for cotton grey fabric in 0.5-5.0 mol/L of NaOH solutions,the complex system exhibits better wettability in 5.0-7.0 mol/L of NaOH solutions,in comparison with either corresponding single surfactant component employed,and wettability is well correlative with the surfactivities of the surfactant.SEM images indicate that the cotton grey fabric is well wetted by the alkaline surfactant solution and the quality of fabric is improved.展开更多
FeCrAl(f)/HA biological functionally gradient materials(FGMs) were successfully fabricated by the hot pressing technique.Scanning electron microscope(SEM),energy dispersive spectrometer(EDS) and bending strength test ...FeCrAl(f)/HA biological functionally gradient materials(FGMs) were successfully fabricated by the hot pressing technique.Scanning electron microscope(SEM),energy dispersive spectrometer(EDS) and bending strength test machine were utilized to characterize the microstructure,component,mechanical properties and the formation of the Ca-deficient apatite on the surface of these materials.The results indicate that an asymmetrical FeCrAl(f)/HA FGM,consolidating powders prepared by mixing HA with 3%–15%(volume fraction) is successfully prepared.Both of the matrix and FeCrAl fiber are integrated very tightly and bite into each other very deeply.And counter diffusion takes place to some extent in two phase interfaces.The elemental compositions of the FeCrAl(f)/HA FGM change progressively.Ca and P contents increase gradually with immersion time increasing,and thereafter approach equilibrium.The bone-like apatite layer forms on the materials surface,which possesses benign bioactivity,and the favorable biocompatibility can provide potential firm fixation between FeCrAl(f)/HA asymmetrical FGM implants and human bone.展开更多
A simple hydrothermal process followed by heat treatment was applied to the preparation of spinel Li1.05Mn1.95O4. In this process, electrolytic manganese dioxide(EMD) and LiOH·H2O were used as starting materials....A simple hydrothermal process followed by heat treatment was applied to the preparation of spinel Li1.05Mn1.95O4. In this process, electrolytic manganese dioxide(EMD) and LiOH·H2O were used as starting materials. The physiochemical properties of the synthesized samples were investigated by thermogravimetry-differential scanning calorimetry(TG-DSC), X-ray diffractometry(XRD), and scanning electronic microscopy(SEM). The results show that the hydrothermally synthesized precursor is an essential amorphous. The precursor can be easily transferred to spinel powders with a homogeneous structure and a regularly-shaped morphology by heat treatment. Li1.05Mn1.95O4 powder obtained by heat treating the precursor at 430 °C for 12 h and then calcining at 800 °C for 12 h shows an excellent cycling performance with an initial charge capacity of 118.2 mA·h·g-1 obtained at 0.5C rate and 93.8% of its original value retained after 100 cycles.展开更多
In order to choose the appropriate reference surface on the machined surface roughness of Si Cp/Al composites, the cutting experiments of Si Cp/Al composites were carried out, and the machined surface topography was m...In order to choose the appropriate reference surface on the machined surface roughness of Si Cp/Al composites, the cutting experiments of Si Cp/Al composites were carried out, and the machined surface topography was measured by OLS3000 Confocal laser scanning microscope. The 3D measured data of machined surface topography were analyzed by the area power spectrum density. The result shows that the texture of machined surface topography in milling of Si Cp/Al composites is almost isotropic. This is the reason that the values of Rq at different locations on the same machined surface are obviously different. Through the comparison of performance of different filtering methods, the robust least squares reference surface can be used to extract the surface roughness of SiC p/Al composites effectively.展开更多
A new approach which adopted the idea of coupling bionics to improve erosion resistance was presented, by taking the desert scorpion as the research object. The anti-erosion characteristic rules and mechanism of deser...A new approach which adopted the idea of coupling bionics to improve erosion resistance was presented, by taking the desert scorpion as the research object. The anti-erosion characteristic rules and mechanism of desert scorpion＇s surface under the dynamics effect of gas/solid mixed media were researched, especially the comprehensive influence mechanism of surface morphology, microstructure, creature flexibility and many other factors was studied. Simulation by CFD software was applied to predict the relative erosion severity. Samples with the coupled bionic configurations and flexibility were produced. Experiment optimum design theory was employed to design experiment scheme. Silica sand of particle size of 105-830 ~tm was used as the erodent. The erosion tests were carried out to validate the simulation results obtained. It is shown that the predicted results are in agreement with those obtained from the experiment. And contrast tests were carried out at the best and worst test points of erosion resistance for four samples. Contrast tests show that the erosion resistance trend occurs in such order with the best erosion resistance as coupling sample, groove, smooth and flexibility, and smooth, and the increasing rate of erosion resistances in sequence of 12.08%, 8.87%, 6.03% in the best test point. But in the poorest point, the increasing rate of erosion resistance is in sequence of 15.64%, 9.53%, 6.59%. The morphologies of eroded surface were examined by the scanning electron microscope, and the possible wear mechanism was discussed.展开更多
Novel organic-inorganic composite photocatalyst offers new opportunities in the practical applications of photocatalysis. Novel visible light-induced Cr-doped Sr Ti O3–carbon nitride intercalation compound(CNIC) comp...Novel organic-inorganic composite photocatalyst offers new opportunities in the practical applications of photocatalysis. Novel visible light-induced Cr-doped Sr Ti O3–carbon nitride intercalation compound(CNIC) composite photocatalysts were synthesized. The composite photocatalyst was characterized by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM), high-resolution transmission electron microscopy(HRTEM), Fourier transform infrared(FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, photoluminescence(PL) spectroscopy, and BET surface area analyzer. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl orange(MO) as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO. For maximizing the photodegradation activity of the composite photocatalysts, the optimal CNIC content was determined. The improved photocatalytic activity of the as-prepared Cr-doped Sr Ti O3–CNIC composite photocatalyst may be attributed to the enhancement of photo-generated electron–hole separations at the interface.展开更多
The effects of surface energy on phase change of water vapor at initial stage of frost growth were studied to find an effective method of restraining frost growth.The mechanism of restraining frost growth by low energ...The effects of surface energy on phase change of water vapor at initial stage of frost growth were studied to find an effective method of restraining frost growth.The mechanism of restraining frost growth by low energy surface(bigger contact angle) was analyzed based on crystal growth theory.Then,the phase change of water vapor and the process of frost growth on the copper and wax energy surfaces were observed using microscope.The results indicate that it is difficult for wax surface(low energy surface),on which there are still water droplets at 100 s,to form critical embryo,so frost growth can be restrained in a way.Water formation,droplet growth,ice formation and dendritic ice growth processes happen on both surfaces,ordinally.But the ice beads,with larger average diameter and sparse distribution on the wax surface,form later(at about 300 s) than that on the copper surface,and the dendritic ice also appears later.All of these support that ice crystal formation and dendritic crystal growth at initial stage of frost growth can be retarded on the low energy surface.展开更多
Activated carbon fiber/carbon nanotube(ACF/CNT) composites were fabricated by chemical vapor deposition(CVD) process.The effects of pyrolysis temperature on properties of ACF/CNT composites,including BET specific surf...Activated carbon fiber/carbon nanotube(ACF/CNT) composites were fabricated by chemical vapor deposition(CVD) process.The effects of pyrolysis temperature on properties of ACF/CNT composites,including BET specific surface area,mass increment rate and adsorption efficiency for rhodamine B in solution,were investigated by scanning electron microscopy.The results show that the pyrolysis temperature is a key factor affecting the qualities of ACF/CNT composites.The mass increment rate and BET specific surface area sharply decrease with the increase of pyrolysis temperatures from 550 ℃ to 850 ℃ and the minimum diameter of CNTs appears at 750 ℃.The maximum adsorption efficiency of ACF/CNT composites for rhodamine B is obtained at 650 ℃.ACF/CNT composites are expected to be useful in adsorption field.展开更多
To improve the conductivity of Y2O3-stabilized ZrO2 （YSZ） based oxygen-ion conductor, Zr0.85Y0.15O1.925-La9.33Si6O26 （YSZ-LSO） composite ceramics with the mass fraction of La9.33Si6O26 （LSO） of 15% were prepared...To improve the conductivity of Y2O3-stabilized ZrO2 （YSZ） based oxygen-ion conductor, Zr0.85Y0.15O1.925-La9.33Si6O26 （YSZ-LSO） composite ceramics with the mass fraction of La9.33Si6O26 （LSO） of 15% were prepared by using a modified coprecipitation method. The phases, microstructures and conductivities of the YSZ, LSO and YSZ-LSO were investigated by X-ray diffraction, electron microscopy and complex impedance, respectively. The results show that the as-calcined powder of YSZ-LSO composite has the grain size less than 10 nm, and the as-sintered composite ceramics are composed of YSZ and LSO phases. The conductivity can be enhanced obviously by composite method. At 700 ℃, the conductivity of the composite ceramic is 0.125 S/cm, which is one order in magnitude higher than that of the YSZ ceramic and two orders in magnitude higher than that of LSO ceramic. By analyzing the impedance spectra and modulus spectra, the interfacial effect on the conductivity improvement was proposed.展开更多
Zn2GeO4 nanorods were prepared by a surfactant-assisted solution phase route.The as-prepared products were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission ...Zn2GeO4 nanorods were prepared by a surfactant-assisted solution phase route.The as-prepared products were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),inductively coupled plasma atomic emission spectrometer(ICP-AES),UV-vis diffuse reflection spectroscopy and photoluminescence(PL) spectroscopy.The possible formation mechanism of Zn2GeO4 nanorods was discussed.It was supposed that the CTA+ cations preferentially adsorb on the planes of Zn2GeO4 nanorods,leading to preferential growth along the c-axis to form the Zn2GeO4 rods with larger aspect ratio and higher surface area,which showed the improved photocatalytic activity for photoreduction of CO2.The photoluminescence(PL) property of Zn2GeO4 nanorods was investigated through the emission spectra.展开更多
The surface states of pyrite(Fe S2) were theoretically investigated using first principle calculation based on the density functional theory(DFT). The results indicate that both the(200) and(311) surfaces of pyrite un...The surface states of pyrite(Fe S2) were theoretically investigated using first principle calculation based on the density functional theory(DFT). The results indicate that both the(200) and(311) surfaces of pyrite undergo significant surface atom relaxation after geometry optimization, which results in a considerable distortion of the surface region. In the normal direction, i.e., perpendicular to the surface, S atoms in the first surface layer move outward from the bulk, while Fe atoms move toward the bulk, forming an S-rich surface. The surface relaxation processes are driven by electrostatic interaction, which is evidenced by a relative decrease in the surface energy after surface relaxation. Such a relaxation process is visually interpreted through the qualitative analysis of molecular mechanics. Atomic force microscopy(AFM) analysis reveals that only sulfur atom is visible on the pyrite surface. This result is consistent with the DFT data. Such S-rich surface has important influence on the flotation properties of pyrite.展开更多
基金Project(2014BAB01B03)supported by the National Key Technology R&D Program During the 12th Five-Yean Plan of ChinaProject(51774286)supported by the National Natural Science Foundation of ChinaProject(BK20150192)supported by the Natural Science Foundation of Jiaaagsu Province,China
文摘The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces were measured directly by atomic force microscopy (AFM) based on the bending mode of the nominal constant compliance regime in AFM force curve in the present study. Surface and solid-liquid interfacial energies were calculated to explain the forming mechanism of the hydration film and atomic force microscopy data. The results show that there are significant differences in the structure and thickness of hydration films on coal and mica surfaces. Hydration film formed on mica surface with the thickness of 22.5 nm. In contrast, the bend was not detected in the nominal constant compliance regime. The van der Waals and polar interactions between both mica and coal and water molecules are characterized by an attractive effect, while the polar attractive free energy between water and mica (-87.36 mN/m) is significantly larger than that between water and coal (-32.89 mN/m), which leads to a thicker and firmer hydration layer on the mica surface. The interfacial interaction free energy of the coal/water/bubble is greater than that of mica. The polar attractive force is large enough to overcome the repulsive van der Waals force and the low energy barrier of film rupture, achieving coal particle bubble adhesion with a total interfacial free energy of-56.30 mN/m.
基金Project(08JJ3104) support by Hunan Provincial Natural Science Foundation of China
文摘The auto-evolved ultrafine copper powders were synlhesized via a novel electrodeposition route performed by ultrasonic dispersion of the electrolyte. The properties of the samples obtained were characterized by X-ray powder diffractometry （XRD）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM） and laser size distribution analyzer （SL） respectively. The formation mechanisms of the powders and the efficiency of the elctrodeposition were discussed. The results show that the as-prepared powders are high-purity copper nanoparticles with the fcc structure taking a mixture of fishbone-like and irregular shapes When the concentration of Cu^2＋ increases from 0.03 to 0.09 mol/L, the average size of copper particles increases from 0.92 to 1.80 μm, and current efficiency of electrodeposition linearly changes from 66.5% to 91.3%.
基金Project(50704036) supported by the National Natural Science Foundation of ChinaProject(08JJ3027) supported by the Natural Science Foundation of Hunan Province, China
文摘Magnesium oxysulfate （MgSO4·5Mg（OH）2·2H2O） flake powders with an average diameter of 2 ~tm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydrothermal synthesis process. The composition, morphology and structural features of the hydrothermal products were examined with X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. The experimental results indicate that in the conditions of n（NaOH）/n（MgSO4） of 1.25, the dosage of w（Na3PO4） crystal additives of 1.0% w（MgSO4）, stirring for 5 h at 180 ℃, the morphology of MgSO4·5Mg（OH）2·2H2O products is flaky and laminar, which is a kind of complex magnesium singlecrystal. The recycling of MgSO4 mother liquor was also investigated to make a full use of the materials and reduce disposal. The results prove that there is no adverse effect on the yield and purity of the products.
基金Project(10274018) supported by the National Natural Science Foundation of China project(Z200102) supported the KeyFoundation of Hebei Normal University project(2002116) supported the Foundation Education Department of of Hebei Provin
文摘FePt granular films were prepared by direct current facing-target magnetron sputtering system onto glass substrates and subsequently in-situ annealed in vacuum. Vibrating sample magnetometer, X-ray diffraction and scanning probe microscope were applied to study the magnetic properties, microstructures, morphologies and domain structures of the samples. （FePt）27Ti73 bilayer films were fabricated at various conditions to investigate the effect of Ti on FePt grains. The results show that without Ti matrix layer, FePt films deposited onto the glass substrates are fcc disordered; with addition of Ti matrix layer, FePt/Ti films form a ternary （FePt）27Ti73 alloy possessing fcc and L10 （111） mixed texture. FePt/（FePt）27Ti73 films with perfectly ordered L10（111） structure and unique magnetic properties can be obtained at Ti thickness of 35nm and substrate temperature of 250℃. The maximum coercivity is more than 240kA/m and the squareness ratio is more than 0.9. The obtained results suggest that the granular FePt/（FePt）27Ti73 films can be applicable to ultrahigh-density magnetic recording media.
基金Project(51274247) supported by the National Natural Science Foundation of ChinaProject(2014zzts177) support by the Fundamental Research Funds for the Central Universities,China
文摘Porous and dense TiNi alloys were successfully fabricated by powder metallurgy(P/M) method, and to further improve their surface biocompatibility, surface modification techniques including grind using silicon-carbide(SiC) paper, acid etching and alkali treatment were employed to produce either irregularly rough surface or micro-porous surface roughness. X-ray diffractometry(XRD), scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDX) attached to SEM were used to characterize surface structure and the Ca-P coatings. Effects of the above surface treatments on the surface morphology, apatite forming ability were systematically investigated. Results indicate that all the above surface treatments increase the apatite forming ability of TiNi alloys in varying degrees when soaked in simulated body fluid(SBF). More apatite coatings formed on TiNi samples sintered at 1050℃ and 1100℃ due to their high porosity and pure TiNi phase that is beneficial to heterogeneous nucleation. Furthermore, more uniform apatite was fabricated on the sample sintered from the mixture of Ni and Ti powders.
基金Project(20573079) supported by the National Natural Science Foundation of China
文摘The wettability,surfactivity and the correlation between wettability and surfactivity of sodium diethylhexylphosphate,sodium diethylhexyl polyoxyethylene phosphate and their complex in NaOH solutions were studied.A complex alkali resistant phosphate surfactant with good permeability was prepared.The wettability of surfactants was investigated by measuring the immersion time,sinking time and capillary effects of nature cotton grey fabric in NaOH solutions.The surfactivity of the surfactants was characterized by measuring the surface tension.The effect of the complex on the surface appearance of cotton grey fabric was also investigated with a scanning electron microscope(SEM) .The results show that all the surfactants exhibit good wettability for cotton grey fabric in 0.5-5.0 mol/L of NaOH solutions,the complex system exhibits better wettability in 5.0-7.0 mol/L of NaOH solutions,in comparison with either corresponding single surfactant component employed,and wettability is well correlative with the surfactivities of the surfactant.SEM images indicate that the cotton grey fabric is well wetted by the alkaline surfactant solution and the quality of fabric is improved.
基金Project(51274247)supported by the National Natural Science Foundation of ChinaProject(2012BAE06B00)supported by the National High Technology Research and Development Program to China+1 种基金Project(2011QNZT046)supported by the Fundamental Research Funds of Central South Universities of ChinaProject supported by Hunan Postdoctoral Scientific Program,China
文摘FeCrAl(f)/HA biological functionally gradient materials(FGMs) were successfully fabricated by the hot pressing technique.Scanning electron microscope(SEM),energy dispersive spectrometer(EDS) and bending strength test machine were utilized to characterize the microstructure,component,mechanical properties and the formation of the Ca-deficient apatite on the surface of these materials.The results indicate that an asymmetrical FeCrAl(f)/HA FGM,consolidating powders prepared by mixing HA with 3%–15%(volume fraction) is successfully prepared.Both of the matrix and FeCrAl fiber are integrated very tightly and bite into each other very deeply.And counter diffusion takes place to some extent in two phase interfaces.The elemental compositions of the FeCrAl(f)/HA FGM change progressively.Ca and P contents increase gradually with immersion time increasing,and thereafter approach equilibrium.The bone-like apatite layer forms on the materials surface,which possesses benign bioactivity,and the favorable biocompatibility can provide potential firm fixation between FeCrAl(f)/HA asymmetrical FGM implants and human bone.
基金Project(50174058)supported by the National Natural Science Foundation of ChinaProject(2011A025)supported by the Glorious Laurel Scholar Program of Guangxi Zhuang Autonomous Region,China
文摘A simple hydrothermal process followed by heat treatment was applied to the preparation of spinel Li1.05Mn1.95O4. In this process, electrolytic manganese dioxide(EMD) and LiOH·H2O were used as starting materials. The physiochemical properties of the synthesized samples were investigated by thermogravimetry-differential scanning calorimetry(TG-DSC), X-ray diffractometry(XRD), and scanning electronic microscopy(SEM). The results show that the hydrothermally synthesized precursor is an essential amorphous. The precursor can be easily transferred to spinel powders with a homogeneous structure and a regularly-shaped morphology by heat treatment. Li1.05Mn1.95O4 powder obtained by heat treating the precursor at 430 °C for 12 h and then calcining at 800 °C for 12 h shows an excellent cycling performance with an initial charge capacity of 118.2 mA·h·g-1 obtained at 0.5C rate and 93.8% of its original value retained after 100 cycles.
基金Projects(51305284,61203208) supported by the National Natural Science Foundation of China
文摘In order to choose the appropriate reference surface on the machined surface roughness of Si Cp/Al composites, the cutting experiments of Si Cp/Al composites were carried out, and the machined surface topography was measured by OLS3000 Confocal laser scanning microscope. The 3D measured data of machined surface topography were analyzed by the area power spectrum density. The result shows that the texture of machined surface topography in milling of Si Cp/Al composites is almost isotropic. This is the reason that the values of Rq at different locations on the same machined surface are obviously different. Through the comparison of performance of different filtering methods, the robust least squares reference surface can be used to extract the surface roughness of SiC p/Al composites effectively.
基金Projects(51205161, 51175220, 51290292) supported by the National Natural Science Foundation of ChinaProjects(20120061120051, 20100061110023) supported by Specialized Research Fund for the Doctoral Program of Higher Education of China+3 种基金Project(OSR-04-04) supported by Cooperation and Innovation to National Potential Oil and Gas for Production and Research, ChinaProject(200905016) supported by Ten Outstanding Youth Fund Project of Jilin University, ChinaProject(2012M511345) supported by China Postdoctoral Science FoundationProject(450060481176) supported by Basic Scientific Research Expenses of Jilin University, China
文摘A new approach which adopted the idea of coupling bionics to improve erosion resistance was presented, by taking the desert scorpion as the research object. The anti-erosion characteristic rules and mechanism of desert scorpion＇s surface under the dynamics effect of gas/solid mixed media were researched, especially the comprehensive influence mechanism of surface morphology, microstructure, creature flexibility and many other factors was studied. Simulation by CFD software was applied to predict the relative erosion severity. Samples with the coupled bionic configurations and flexibility were produced. Experiment optimum design theory was employed to design experiment scheme. Silica sand of particle size of 105-830 ~tm was used as the erodent. The erosion tests were carried out to validate the simulation results obtained. It is shown that the predicted results are in agreement with those obtained from the experiment. And contrast tests were carried out at the best and worst test points of erosion resistance for four samples. Contrast tests show that the erosion resistance trend occurs in such order with the best erosion resistance as coupling sample, groove, smooth and flexibility, and smooth, and the increasing rate of erosion resistances in sequence of 12.08%, 8.87%, 6.03% in the best test point. But in the poorest point, the increasing rate of erosion resistance is in sequence of 15.64%, 9.53%, 6.59%. The morphologies of eroded surface were examined by the scanning electron microscope, and the possible wear mechanism was discussed.
基金Project(51208102)supported by the National Natural Science Foundation of China
文摘Novel organic-inorganic composite photocatalyst offers new opportunities in the practical applications of photocatalysis. Novel visible light-induced Cr-doped Sr Ti O3–carbon nitride intercalation compound(CNIC) composite photocatalysts were synthesized. The composite photocatalyst was characterized by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM), high-resolution transmission electron microscopy(HRTEM), Fourier transform infrared(FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, photoluminescence(PL) spectroscopy, and BET surface area analyzer. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl orange(MO) as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO. For maximizing the photodegradation activity of the composite photocatalysts, the optimal CNIC content was determined. The improved photocatalytic activity of the as-prepared Cr-doped Sr Ti O3–CNIC composite photocatalyst may be attributed to the enhancement of photo-generated electron–hole separations at the interface.
基金Project(50376052) supported by the National Natural Science Foundation of ChinaProject(307013) supported by the Key Project of Chinese Ministry of EducationProject(2008BAJ12B02) supported by the National Science and Technology Pillar Program in the 11th Five-Year Plan Period
文摘The effects of surface energy on phase change of water vapor at initial stage of frost growth were studied to find an effective method of restraining frost growth.The mechanism of restraining frost growth by low energy surface(bigger contact angle) was analyzed based on crystal growth theory.Then,the phase change of water vapor and the process of frost growth on the copper and wax energy surfaces were observed using microscope.The results indicate that it is difficult for wax surface(low energy surface),on which there are still water droplets at 100 s,to form critical embryo,so frost growth can be restrained in a way.Water formation,droplet growth,ice formation and dendritic ice growth processes happen on both surfaces,ordinally.But the ice beads,with larger average diameter and sparse distribution on the wax surface,form later(at about 300 s) than that on the copper surface,and the dendritic ice also appears later.All of these support that ice crystal formation and dendritic crystal growth at initial stage of frost growth can be retarded on the low energy surface.
基金Project(50802115) supported by the National Natural Science Foundation of ChinaProject(2010FJ4075) supported by the Science and Technology Plan of Hunan ProvinceProject(CDJJ-10010205) supported by Changsha University
文摘Activated carbon fiber/carbon nanotube(ACF/CNT) composites were fabricated by chemical vapor deposition(CVD) process.The effects of pyrolysis temperature on properties of ACF/CNT composites,including BET specific surface area,mass increment rate and adsorption efficiency for rhodamine B in solution,were investigated by scanning electron microscopy.The results show that the pyrolysis temperature is a key factor affecting the qualities of ACF/CNT composites.The mass increment rate and BET specific surface area sharply decrease with the increase of pyrolysis temperatures from 550 ℃ to 850 ℃ and the minimum diameter of CNTs appears at 750 ℃.The maximum adsorption efficiency of ACF/CNT composites for rhodamine B is obtained at 650 ℃.ACF/CNT composites are expected to be useful in adsorption field.
基金Project(50872155) supported by the National Natural Science Foundation of China
文摘To improve the conductivity of Y2O3-stabilized ZrO2 （YSZ） based oxygen-ion conductor, Zr0.85Y0.15O1.925-La9.33Si6O26 （YSZ-LSO） composite ceramics with the mass fraction of La9.33Si6O26 （LSO） of 15% were prepared by using a modified coprecipitation method. The phases, microstructures and conductivities of the YSZ, LSO and YSZ-LSO were investigated by X-ray diffraction, electron microscopy and complex impedance, respectively. The results show that the as-calcined powder of YSZ-LSO composite has the grain size less than 10 nm, and the as-sintered composite ceramics are composed of YSZ and LSO phases. The conductivity can be enhanced obviously by composite method. At 700 ℃, the conductivity of the composite ceramic is 0.125 S/cm, which is one order in magnitude higher than that of the YSZ ceramic and two orders in magnitude higher than that of LSO ceramic. By analyzing the impedance spectra and modulus spectra, the interfacial effect on the conductivity improvement was proposed.
基金Project(51208102)supported by the National Natural Science Foundation of China
文摘Zn2GeO4 nanorods were prepared by a surfactant-assisted solution phase route.The as-prepared products were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),inductively coupled plasma atomic emission spectrometer(ICP-AES),UV-vis diffuse reflection spectroscopy and photoluminescence(PL) spectroscopy.The possible formation mechanism of Zn2GeO4 nanorods was discussed.It was supposed that the CTA+ cations preferentially adsorb on the planes of Zn2GeO4 nanorods,leading to preferential growth along the c-axis to form the Zn2GeO4 rods with larger aspect ratio and higher surface area,which showed the improved photocatalytic activity for photoreduction of CO2.The photoluminescence(PL) property of Zn2GeO4 nanorods was investigated through the emission spectra.
基金Project(51464029)supported by the National Natural Science Foundation of ChinaProject(2014M562343)supported by China Postdoctoral Science FoundationProject(KKSY201421110)supported by the Scholar Development Project of Yunnan Province,China
文摘The surface states of pyrite(Fe S2) were theoretically investigated using first principle calculation based on the density functional theory(DFT). The results indicate that both the(200) and(311) surfaces of pyrite undergo significant surface atom relaxation after geometry optimization, which results in a considerable distortion of the surface region. In the normal direction, i.e., perpendicular to the surface, S atoms in the first surface layer move outward from the bulk, while Fe atoms move toward the bulk, forming an S-rich surface. The surface relaxation processes are driven by electrostatic interaction, which is evidenced by a relative decrease in the surface energy after surface relaxation. Such a relaxation process is visually interpreted through the qualitative analysis of molecular mechanics. Atomic force microscopy(AFM) analysis reveals that only sulfur atom is visible on the pyrite surface. This result is consistent with the DFT data. Such S-rich surface has important influence on the flotation properties of pyrite.
