The abrasive wear characteristics of Al_2O_3/PA1010 composite coatings on thesurface of quenched and low-temperature temper steel 45 were tested on the template abrasive weartesting machine and the same uncoated steel...The abrasive wear characteristics of Al_2O_3/PA1010 composite coatings on thesurface of quenched and low-temperature temper steel 45 were tested on the template abrasive weartesting machine and the same uncoated steel 45 was used as a reference material. Experimentalresults showed that the abrasive wear resistance of Al_2O_3/PA1010 composite coatings has a goodlinear relationship with the volume fraction of Al_2O_3 particles in Al_2O_3/PA1010 compositecoatings, and the linear correlative coefficient is 0.979. Under the experimental conditions, thesize of Al_2O_3 particles (40.5-161.0 μm) has little influence on the abrasive wear resistance ofAl_2O_3/PA1010 composite coatings. By treating the surface of Al_2O_3 particles with a suitablebonding agent, the distribution of Al_2O_3 particles in matrix PA1010 is more homogeneous and thebonding state between Al_2O_3 particles and matrix PA1010 is better. Therefore, the Al_2O_3particles in Al_2O_3/PA1010 composite coatings make the Al_2O_3/PA1010 composite coatings havebetter abrasive wear resistance than PA1010 coatings. The wear resistance of Al_2O_3/PA1010composite coatings is about 45% compared with that of steel 45.展开更多
Ni-W-P matrix composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by means of pulse electrodeposition,and the high-temperature oxidation behavior was investigated.The result...Ni-W-P matrix composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by means of pulse electrodeposition,and the high-temperature oxidation behavior was investigated.The results show that when the oxidation time is controlled in 1 h,oxidation kinetics curve between oxidation mass gain rate and oxidation temperature of CeO2-SiO2/Ni-W-P composites accords with the index increasing law.When the oxidation temperature is controlled at 300℃,the kinetics curve between oxidation mass gain rate and oxidation time accords with the linear increasing law.The composites as-deposited are in the amorphous state and turn into the crystal state at 400℃.The microstructures of oxidation film on the composites will change from the compact state to the loose state with increasing oxidation temperature to 800℃.They are still continuous and compact,and there are no crackle,strip and falling-out.CeO2 and SiO2 nano-particles co-deposited into Ni-W-P alloy can improve the high-temperature oxidation resistance.展开更多
A hydrophobic coating of the silica fiber reinforced silica composites(SiO2f/SiO2) was synthesized by sol-gel method using methyltriethoxy-silane(MTES) and boric acid(B(OH)3) as raw materials. The relationship among b...A hydrophobic coating of the silica fiber reinforced silica composites(SiO2f/SiO2) was synthesized by sol-gel method using methyltriethoxy-silane(MTES) and boric acid(B(OH)3) as raw materials. The relationship among boron doping, chemical structure of precursors and durability of hydrophobic coatings was discussed. The Si-O-B and methyl groups were successfully introduced in the gel precursors according to the FT-IR and XPS results. The resins were filled in the internal and surface holes of the SiO2f/SiO2 composites partially or completely, which is beneficial to reduce the physical adsorption of the moisture. In addition, hydroxyl groups of the SiO2f/SiO2 composites reacted with the resins and hydrophobic methyl groups were introduced, leading to the reduction of the chemical adsorption of water. Also, the boron doping was beneficial to enhancing the physical cross-linking between the coating and the SiO2f/SiO2 composites, and improved the adhesion of the coating to the substrate. The results show that the optimal hydrophobic coating with contact angle 130.33°, moisture absorption 0.33% and adhesion level 1 is obtained when the molar ratio of MTES to B(OH)3 is 10:4. The real permittivity of M10B4 is constant in the range of 2.32–2.51 and the dielectric tangent loss is constant in the range of 5.5 × 10-4–8.7 × 10-3. The hydrophobic coating has excellent dielectric properties.展开更多
In-situ TiB2 particles reinforced 2014 aluminum alloy composite was prepared using an exothermic reaction process with K2TiF6 and KBF4 salts. The effects of CeO2 additive on the microstructure and properties of in-sit...In-situ TiB2 particles reinforced 2014 aluminum alloy composite was prepared using an exothermic reaction process with K2TiF6 and KBF4 salts. The effects of CeO2 additive on the microstructure and properties of in-situ TiB2/2014 composite were investigated. The results showed that CeO2 at high temperature exhibits the same function as Ce. When 0.5% (mass fraction) CeO2 additive was added, the dispersion of TiB2 particles in the matrix is improved significantly, and particles have no obvious settlement. The dispersing mechanism of TiB2 particles in 2014 Al alloy matrix was explained. Compared with the composite without CeO2, the hardness, tensile strength, yield strength and elongation of the composite with CeO2 addition are greatly increased in as-cast condition.展开更多
The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition beha...The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition behavior and SO2 poisoning over V2 O5-MoO3/TiO2 catalysts modified with CeO2 and SiO2 were investigated.By the means of characterization analysis,it was found that the addition of SiO2 into VMo/Ti-Ce had an impact on the interaction existed between catalyst surface atoms and NH4 HSO4.Temperatureprogrammed methods and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)experiments indicated that the doping of SiO2 promoted the decomposition of deposited NH4 HSO4 on VMo/Ti-Ce catalyst surface by reducing the thermal stability of NH4 HSO4 and enhancing the NH4 HSO4 reactivity with NO in low temperature.And this improvement may be the reason for the better catalytic activity than VMo/Ti-Ce in the case of NH4 HSO4 deposition.Accompanied with cerium sulfate species generated over catalyst surface,the conversion of SO2 to SO3 was inhibited in SiCe mixed catalyst.The addition of SiO2 could promote the decomposition of cerium sulfate,which may be a potential strategy to enhance the resistance of SO2 poisoning over CeO2-modifed catalysts.展开更多
In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Comp...In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Compared to the commercial polypropylene(PP) separator,the sponge-like PSA/SiO_2 composite possesses better physical and electrochemical properties,such as higher porosity,ionic conductivity,thermal stability and flame retarding ability.The LiCoO_2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator.Moreover,the sponge-like composite separator can ensure the normal operation of LiCoO_2/Li half-cell at an extremely high temperature of 90 °C,while the commercial PP separator cannot.All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO_2 composite separator is really a promising separator for high performance LIBs.展开更多
Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor(VDMOS) devices with composite SiO2-Si3N4 film gates are investigated.The relationships amon...Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor(VDMOS) devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.展开更多
Ablation under oxyacetylene torch with heat flux of 4186.8(10%kW/m2 for 20 s was performed to evaluate the ablation resistance of C/C-SiC composites fabricated by chemical vapor infiltration(CVI) combined with liqu...Ablation under oxyacetylene torch with heat flux of 4186.8(10%kW/m2 for 20 s was performed to evaluate the ablation resistance of C/C-SiC composites fabricated by chemical vapor infiltration(CVI) combined with liquid silicon infiltration(LSI) process.The results indicated that C/C-SiC composites present a better ablation resistance than C/C composites without doped SiC.The doped SiC and the ablation products SiO2 derived from it play key roles in ablation process.Bulk quantities of SiO2 nanowires with diameter of 80 nm-150 nm and length of tens microns were observed on the surface of specimens after ablation.The growth mechanism of the SiO_2 nanowires was interpreted with a developed vapor-liquid-solid(VLS) driven by the temperature gradient.展开更多
(PEO)8LiClO4-SiO2 composite polymer electrolytes(CPEs)were prepared by in-situ reaction,in which ethyl-orthosilicate(TEOS)was catalyzed by HCl and NH3.H2O,respectively.The ionic conductivity,the contact angle and the ...(PEO)8LiClO4-SiO2 composite polymer electrolytes(CPEs)were prepared by in-situ reaction,in which ethyl-orthosilicate(TEOS)was catalyzed by HCl and NH3.H2O,respectively.The ionic conductivity,the contact angle and the morphology of inorganic particles in the CPEs were investigated by AC impedance spectra,contact angle method and TEM.The conductivities of acid-catalyzed CPE and alkali-catalyzed CPE are 2.2×10-5and 1.1×10-5S/cm respectively at 30℃.The results imply that the catalyst plays an important role in the structure of in-situ preparation of SiO2,and influences the surface energy and conductivity of CPE films directly.Meanwhile,the ionic conductivity is related to the surface energy.展开更多
Three-dimensional (3D) five-directional braided (SiO2)/SiO2 composites were prepared by silicasol-infiltration-sintering (SIS) method. The flexural properties and microstructures were studied. The flexural stren...Three-dimensional (3D) five-directional braided (SiO2)/SiO2 composites were prepared by silicasol-infiltration-sintering (SIS) method. The flexural properties and microstructures were studied. The flexural strength and flexural elastic modulus were found to be 73 MPa and 12 GPa, respectively. The results of stress vs deflection curve and SEM examinations revealed that the fracture mechanism of 3D, five-directional braided (SiO2)/SiO2 composite was a mixture mode of ductile and brittle. The ductile mode was attributed to the weak bonding strength of fiber/matrix at low temperature. The brittle fracture might be caused by the propagation of micro defect or crack, which existed in the as-prepared composites for the ten-cycle process.展开更多
The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmissi...The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO, films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0((o) under bar) are obtained by the addition of 10%-20% SiO2 in mole fraction.展开更多
A silicon dioxide fiber-reinforced silicon nitride matrix (SiOJSi3N4) composite used for radomes was prepared by chemical vapor infiltration (CVI) process using the SiCl4-NH3-H2 system. The effects of the process ...A silicon dioxide fiber-reinforced silicon nitride matrix (SiOJSi3N4) composite used for radomes was prepared by chemical vapor infiltration (CVI) process using the SiCl4-NH3-H2 system. The effects of the process conditions, including infiltration temperature, infiltration time, and gas flux were investigated. The energy dispersion spectra (EDS) result showed that the main elements of this composite contained Si, N, and O. The X-ray diffraction (XRD) results indicated that phases of the composite before and after treatment at 1350℃ were all amorphous. A little fiber pull-out was observed on the cross section of the composite by scan electron microscope (SEM). As a result, the composite exhibited good thermal stability, but an appropriate interface was necessary between the fiber and the matrix.展开更多
In the present work, structure changes during (SiO2) composites have been investigated systematically stretching of isotactic polypropylene (iPP) and iPP/silicon dioxide The or-form crystal structure of both iPP a...In the present work, structure changes during (SiO2) composites have been investigated systematically stretching of isotactic polypropylene (iPP) and iPP/silicon dioxide The or-form crystal structure of both iPP and iPP/SiO2 composites is destroyed and transforms into the mesophase as the samples are stretched at a low temperature (35℃), while stretching at high temperatures (90℃ and 120℃) can restrain the appearance of defects and keep the perfection of crystal structure. FTIR results reveal that the stretching temperatures show no obvious difference of the effect on the orientation of pure iPP, however, the orientation of iPP/SiO2 composites is greatly changed by the tensile temperature. In the case of micron-sized SiO2 particles (average particle diameter d 〉 1 μm), the orientation of the composites is lower than that of pure iPP at all stretching temperatures. The above results suggest that the stretching temperature and the SiO2 particle size have great influence on the structure variation and orientation behavior of iPP/SiO2 composites.展开更多
Silica( SiO_2) based aerogel/xerogel materials have been received ever-growing attentions for versatile applications. However,the widespread applications are narrowed by the inert properties,fragile and brittle nature...Silica( SiO_2) based aerogel/xerogel materials have been received ever-growing attentions for versatile applications. However,the widespread applications are narrowed by the inert properties,fragile and brittle natureof silica materials and cumbersome preparation processes. In this paper,titania( TiO_2) was introduced into SiO_2 matrix to form photocatalytic hybrid gels. The TiO_2/SiO_2 composites were then reinforced by the impregnation of various fibrillary reinforcements,such as glass,mullite mineral and ceramic fibers. The properties of the composites were studied systematically in terms of fiberstability,microstructure,chemical interaction and thermal conductivity. The final xerogel composites displayed improved monolithic geometry,satisfied thermal conductivity(0. 09-0. 25 W·m-1·K-1) and optimized photocatalytic performance(85% removal of model pollutant of methyl orange( Mo)),which could be expected to be a feasible route to multi-functional building facades in the future.展开更多
Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a nat...Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.展开更多
Hollow B–SiO2@TiO2 composites were prepared by the wet chemical deposition method starting from TiCl4 and hollow B–SiO2 microspheres.TiO2 layers composed of anatase TiO2 nanoparticles were coated on the surfaces of ...Hollow B–SiO2@TiO2 composites were prepared by the wet chemical deposition method starting from TiCl4 and hollow B–SiO2 microspheres.TiO2 layers composed of anatase TiO2 nanoparticles were coated on the surfaces of the hollow B–SiO2 microspheres probably through the formation of Ti—O—Si and Ti—O—B bonds.A great number of—OH groups were also present at the TiO2 coating layers.The presence of Ti—O—Si bonds and Ti—O—B bonds resulted in the formation of defects in the TiO2 coating layers,which decreased the band gap of the TiO2 coating layers to ca.3.0 eV and endowed the TiO2 coating layers with visible light absorption performance.The buoyancy hollow B–SiO2@TiO2 composites exhibited high photocatalytic activities for the degradation of ammonia-nitrogen and green algae.The conversion of ammonia-nitrogen reached 65%when the degradation of ammonia-nitrogen(43 mg·L-1 at pH value of 8)was catalyzed by the B–SiO2@TiO2(100:10)composite under the simulated solar light irradiation at 35°C for 660 min.The green algae(5 mg·L-1)were almost completely degraded over the B–SiO@TiO2(100:20)photocatalyst under the visible light irradiation at 35°C for 510 min.展开更多
Silicon(Si) materials as anode materials for applications in lithium-ion batteries(LIBs) have received increasing attention.Among the Si materials,the electrochemical properties of SiOx-based(0<x≤2)composites are ...Silicon(Si) materials as anode materials for applications in lithium-ion batteries(LIBs) have received increasing attention.Among the Si materials,the electrochemical properties of SiOx-based(0<x≤2)composites are the most prominent.However,due to the cycling stability of SiOx being far from practical,there are some problems,such as Iow initial coulombic efficiency(ICE),obvious volume expansion and poor conductivity.Researchers in various countries have optimized the electrochemical properties of SiOx-based composites by means of pore formation,surface modification,and the choice of constituents.In this review,SiOx-based composites are classified into three categories based on the valency of Si(SiO2 composites,SiO composites and SiOx(0<x<2) composites).The synthesis,morphologies and electrochemical properties of the SiOx-based composites that are applied in LIB are discussed.Finally,the prope rties of several common SiOx-based composites are briefly compared and the challenges faced by SiOx-based composites are highlight.展开更多
Supermacroporous composite cryogels embedded with SiO2 nanoparticles were prepared by radical cryogenic copolymerization of the reactive monomer mixture of acrylamide(AAm) and N,N-methylene-bis-acrylamide(MBAAm) c...Supermacroporous composite cryogels embedded with SiO2 nanoparticles were prepared by radical cryogenic copolymerization of the reactive monomer mixture of acrylamide(AAm) and N,N-methylene-bis-acrylamide(MBAAm) containing SiO2 nanoparticles(mass ratios of nanoparticles to the monomer AAm from 0.01 to 0.08) under the freezing-temperature variation condition in glass columns.The properties of these composite cryogels were measured.The height equivalent to theoretical plate(HETP) of the cryogel beds at different liquid flow rates was determined by residence time distribution(RTD) using tracer pulse-response method.The composite cryogel matrix embedded with the mass fraction of SiO2 nanoparticles of 0.02 presented the best properties and was employed in the following graft polymerization.Chromatographic process of lysozyme in the composite cryogel grafted with 2-acrylamido-2-methyl-1-propanesulfonic acid(AMPSA) was carried out to evaluate the protein breakthrough and elution characteristics.The chromatography can be carried out at relatively high superficial velocity,i.e.,15 cm·min-1,indicating the satisfactory mechanical strength due to the embedded nanoparticles.展开更多
摘要The abrasive wear characteristics of Al_2O_3/PA1010 composite coatings on thesurface of quenched and low-temperature temper steel 45 were tested on the template abrasive weartesting machine and the same uncoated steel 45 was used as a reference material. Experimentalresults showed that the abrasive wear resistance of Al_2O_3/PA1010 composite coatings has a goodlinear relationship with the volume fraction of Al_2O_3 particles in Al_2O_3/PA1010 compositecoatings, and the linear correlative coefficient is 0.979. Under the experimental conditions, thesize of Al_2O_3 particles (40.5-161.0 μm) has little influence on the abrasive wear resistance ofAl_2O_3/PA1010 composite coatings. By treating the surface of Al_2O_3 particles with a suitablebonding agent, the distribution of Al_2O_3 particles in matrix PA1010 is more homogeneous and thebonding state between Al_2O_3 particles and matrix PA1010 is better. Therefore, the Al_2O_3particles in Al_2O_3/PA1010 composite coatings make the Al_2O_3/PA1010 composite coatings havebetter abrasive wear resistance than PA1010 coatings. The wear resistance of Al_2O_3/PA1010composite coatings is about 45% compared with that of steel 45.
基金Project(20806035)supported by the National Natural Science Foundation of ChinaProject(2007E187M)supported by the Applied Basic Research Plans Program of Yunnan Province,China+2 种基金Project supported by the Foundation for Leaders of Disciplines in Science and Technology of Yunnan Province,ChinaProject(08C0025)supported by the Scientific Research Fund of Yunnan Provincial Education Department,ChinaProject supported by the Training Foundation for Talents of Kunming University of Science and Technology,China
摘要Ni-W-P matrix composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by means of pulse electrodeposition,and the high-temperature oxidation behavior was investigated.The results show that when the oxidation time is controlled in 1 h,oxidation kinetics curve between oxidation mass gain rate and oxidation temperature of CeO2-SiO2/Ni-W-P composites accords with the index increasing law.When the oxidation temperature is controlled at 300℃,the kinetics curve between oxidation mass gain rate and oxidation time accords with the linear increasing law.The composites as-deposited are in the amorphous state and turn into the crystal state at 400℃.The microstructures of oxidation film on the composites will change from the compact state to the loose state with increasing oxidation temperature to 800℃.They are still continuous and compact,and there are no crackle,strip and falling-out.CeO2 and SiO2 nano-particles co-deposited into Ni-W-P alloy can improve the high-temperature oxidation resistance.
基金supported by the Taishan Scholar Project(No.ts201511080)the National Natural Science Foundation of China(Nos.51672059,51172050,51102060 and 51302050)the Natural Scientific Research Innovation Foundation in Harbin Institute of Technology(No.HIT.NSRIF.2014129)
摘要A hydrophobic coating of the silica fiber reinforced silica composites(SiO2f/SiO2) was synthesized by sol-gel method using methyltriethoxy-silane(MTES) and boric acid(B(OH)3) as raw materials. The relationship among boron doping, chemical structure of precursors and durability of hydrophobic coatings was discussed. The Si-O-B and methyl groups were successfully introduced in the gel precursors according to the FT-IR and XPS results. The resins were filled in the internal and surface holes of the SiO2f/SiO2 composites partially or completely, which is beneficial to reduce the physical adsorption of the moisture. In addition, hydroxyl groups of the SiO2f/SiO2 composites reacted with the resins and hydrophobic methyl groups were introduced, leading to the reduction of the chemical adsorption of water. Also, the boron doping was beneficial to enhancing the physical cross-linking between the coating and the SiO2f/SiO2 composites, and improved the adhesion of the coating to the substrate. The results show that the optimal hydrophobic coating with contact angle 130.33°, moisture absorption 0.33% and adhesion level 1 is obtained when the molar ratio of MTES to B(OH)3 is 10:4. The real permittivity of M10B4 is constant in the range of 2.32–2.51 and the dielectric tangent loss is constant in the range of 5.5 × 10-4–8.7 × 10-3. The hydrophobic coating has excellent dielectric properties.
基金Project (2008AA03A239) supported by the High-tech Research and Development Program of China
摘要In-situ TiB2 particles reinforced 2014 aluminum alloy composite was prepared using an exothermic reaction process with K2TiF6 and KBF4 salts. The effects of CeO2 additive on the microstructure and properties of in-situ TiB2/2014 composite were investigated. The results showed that CeO2 at high temperature exhibits the same function as Ce. When 0.5% (mass fraction) CeO2 additive was added, the dispersion of TiB2 particles in the matrix is improved significantly, and particles have no obvious settlement. The dispersing mechanism of TiB2 particles in 2014 Al alloy matrix was explained. Compared with the composite without CeO2, the hardness, tensile strength, yield strength and elongation of the composite with CeO2 addition are greatly increased in as-cast condition.
基金supported by the National Natural Science Foundation of China(No.51576039)
摘要The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition behavior and SO2 poisoning over V2 O5-MoO3/TiO2 catalysts modified with CeO2 and SiO2 were investigated.By the means of characterization analysis,it was found that the addition of SiO2 into VMo/Ti-Ce had an impact on the interaction existed between catalyst surface atoms and NH4 HSO4.Temperatureprogrammed methods and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)experiments indicated that the doping of SiO2 promoted the decomposition of deposited NH4 HSO4 on VMo/Ti-Ce catalyst surface by reducing the thermal stability of NH4 HSO4 and enhancing the NH4 HSO4 reactivity with NO in low temperature.And this improvement may be the reason for the better catalytic activity than VMo/Ti-Ce in the case of NH4 HSO4 deposition.Accompanied with cerium sulfate species generated over catalyst surface,the conversion of SO2 to SO3 was inhibited in SiCe mixed catalyst.The addition of SiO2 could promote the decomposition of cerium sulfate,which may be a potential strategy to enhance the resistance of SO2 poisoning over CeO2-modifed catalysts.
基金Supported by the funding from "135" Projects Fund of CAS-QIBEBT Director Innovation FoundationThink-Tank Mutual Fund of Qingdao Energy Storage Industry Scientific Research+3 种基金Qingdao Key Lab of Solar Energy Utilization and Energy Storage Technologythe Strategic Priority Research Program of the Chinese Academy of Sciences(XDA09010105)National Natural Science Foundation of China(51502319)Shandong Provincial Natural Science Foundation(ZR2016BQ18)
摘要In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Compared to the commercial polypropylene(PP) separator,the sponge-like PSA/SiO_2 composite possesses better physical and electrochemical properties,such as higher porosity,ionic conductivity,thermal stability and flame retarding ability.The LiCoO_2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator.Moreover,the sponge-like composite separator can ensure the normal operation of LiCoO_2/Li half-cell at an extremely high temperature of 90 °C,while the commercial PP separator cannot.All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO_2 composite separator is really a promising separator for high performance LIBs.
摘要Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor(VDMOS) devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20110006110025)the National Natural Science Foundation of China(Grant No.U1134102)
摘要Ablation under oxyacetylene torch with heat flux of 4186.8(10%kW/m2 for 20 s was performed to evaluate the ablation resistance of C/C-SiC composites fabricated by chemical vapor infiltration(CVI) combined with liquid silicon infiltration(LSI) process.The results indicated that C/C-SiC composites present a better ablation resistance than C/C composites without doped SiC.The doped SiC and the ablation products SiO2 derived from it play key roles in ablation process.Bulk quantities of SiO2 nanowires with diameter of 80 nm-150 nm and length of tens microns were observed on the surface of specimens after ablation.The growth mechanism of the SiO_2 nanowires was interpreted with a developed vapor-liquid-solid(VLS) driven by the temperature gradient.
摘要(PEO)8LiClO4-SiO2 composite polymer electrolytes(CPEs)were prepared by in-situ reaction,in which ethyl-orthosilicate(TEOS)was catalyzed by HCl and NH3.H2O,respectively.The ionic conductivity,the contact angle and the morphology of inorganic particles in the CPEs were investigated by AC impedance spectra,contact angle method and TEM.The conductivities of acid-catalyzed CPE and alkali-catalyzed CPE are 2.2×10-5and 1.1×10-5S/cm respectively at 30℃.The results imply that the catalyst plays an important role in the structure of in-situ preparation of SiO2,and influences the surface energy and conductivity of CPE films directly.Meanwhile,the ionic conductivity is related to the surface energy.
基金Funded by the Basic Research Project of Science and Technology of Jiangsu Province(No.BK2009002)the National Natural ScienceFoundation of China(No.61176062)the Fundamental Research Funds for the Central Universities(No.NS2013061)
摘要Three-dimensional (3D) five-directional braided (SiO2)/SiO2 composites were prepared by silicasol-infiltration-sintering (SIS) method. The flexural properties and microstructures were studied. The flexural strength and flexural elastic modulus were found to be 73 MPa and 12 GPa, respectively. The results of stress vs deflection curve and SEM examinations revealed that the fracture mechanism of 3D, five-directional braided (SiO2)/SiO2 composite was a mixture mode of ductile and brittle. The ductile mode was attributed to the weak bonding strength of fiber/matrix at low temperature. The brittle fracture might be caused by the propagation of micro defect or crack, which existed in the as-prepared composites for the ten-cycle process.
基金This work was financially supported by the Foundation for University Key Teachers by the Ministry of Education, theKey Resear
摘要The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO, films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0((o) under bar) are obtained by the addition of 10%-20% SiO2 in mole fraction.
基金This study was financially supported by the Key Foundation of National Science in China (No. 90405015), the National Elitist Youth Foundation of China (No. 50425208the Doctorate Foundation of Northwestern Polytechnical University (CX200505).
摘要A silicon dioxide fiber-reinforced silicon nitride matrix (SiOJSi3N4) composite used for radomes was prepared by chemical vapor infiltration (CVI) process using the SiCl4-NH3-H2 system. The effects of the process conditions, including infiltration temperature, infiltration time, and gas flux were investigated. The energy dispersion spectra (EDS) result showed that the main elements of this composite contained Si, N, and O. The X-ray diffraction (XRD) results indicated that phases of the composite before and after treatment at 1350℃ were all amorphous. A little fiber pull-out was observed on the cross section of the composite by scan electron microscope (SEM). As a result, the composite exhibited good thermal stability, but an appropriate interface was necessary between the fiber and the matrix.
基金financially supported by the National Natural Science Foundation of China (Nos. 51073004 and 21074141)the China National Funds for Distinguished Young Scientists (No. 50925313)
摘要In the present work, structure changes during (SiO2) composites have been investigated systematically stretching of isotactic polypropylene (iPP) and iPP/silicon dioxide The or-form crystal structure of both iPP and iPP/SiO2 composites is destroyed and transforms into the mesophase as the samples are stretched at a low temperature (35℃), while stretching at high temperatures (90℃ and 120℃) can restrain the appearance of defects and keep the perfection of crystal structure. FTIR results reveal that the stretching temperatures show no obvious difference of the effect on the orientation of pure iPP, however, the orientation of iPP/SiO2 composites is greatly changed by the tensile temperature. In the case of micron-sized SiO2 particles (average particle diameter d 〉 1 μm), the orientation of the composites is lower than that of pure iPP at all stretching temperatures. The above results suggest that the stretching temperature and the SiO2 particle size have great influence on the structure variation and orientation behavior of iPP/SiO2 composites.
基金National Natural Science Foundations of China(Nos.51308079,51408073,51678080,51678081)
摘要Silica( SiO_2) based aerogel/xerogel materials have been received ever-growing attentions for versatile applications. However,the widespread applications are narrowed by the inert properties,fragile and brittle natureof silica materials and cumbersome preparation processes. In this paper,titania( TiO_2) was introduced into SiO_2 matrix to form photocatalytic hybrid gels. The TiO_2/SiO_2 composites were then reinforced by the impregnation of various fibrillary reinforcements,such as glass,mullite mineral and ceramic fibers. The properties of the composites were studied systematically in terms of fiberstability,microstructure,chemical interaction and thermal conductivity. The final xerogel composites displayed improved monolithic geometry,satisfied thermal conductivity(0. 09-0. 25 W·m-1·K-1) and optimized photocatalytic performance(85% removal of model pollutant of methyl orange( Mo)),which could be expected to be a feasible route to multi-functional building facades in the future.
摘要Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.
基金Supported by the National Natural Science Foundation of China(21506078).
摘要Hollow B–SiO2@TiO2 composites were prepared by the wet chemical deposition method starting from TiCl4 and hollow B–SiO2 microspheres.TiO2 layers composed of anatase TiO2 nanoparticles were coated on the surfaces of the hollow B–SiO2 microspheres probably through the formation of Ti—O—Si and Ti—O—B bonds.A great number of—OH groups were also present at the TiO2 coating layers.The presence of Ti—O—Si bonds and Ti—O—B bonds resulted in the formation of defects in the TiO2 coating layers,which decreased the band gap of the TiO2 coating layers to ca.3.0 eV and endowed the TiO2 coating layers with visible light absorption performance.The buoyancy hollow B–SiO2@TiO2 composites exhibited high photocatalytic activities for the degradation of ammonia-nitrogen and green algae.The conversion of ammonia-nitrogen reached 65%when the degradation of ammonia-nitrogen(43 mg·L-1 at pH value of 8)was catalyzed by the B–SiO2@TiO2(100:10)composite under the simulated solar light irradiation at 35°C for 660 min.The green algae(5 mg·L-1)were almost completely degraded over the B–SiO@TiO2(100:20)photocatalyst under the visible light irradiation at 35°C for 510 min.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.21671170,21673203, 21201010)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)+2 种基金Program for New Century Excellent Talents of the University in China(NCET,No.13-0645)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.XSJCX17-015)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
摘要Silicon(Si) materials as anode materials for applications in lithium-ion batteries(LIBs) have received increasing attention.Among the Si materials,the electrochemical properties of SiOx-based(0<x≤2)composites are the most prominent.However,due to the cycling stability of SiOx being far from practical,there are some problems,such as Iow initial coulombic efficiency(ICE),obvious volume expansion and poor conductivity.Researchers in various countries have optimized the electrochemical properties of SiOx-based composites by means of pore formation,surface modification,and the choice of constituents.In this review,SiOx-based composites are classified into three categories based on the valency of Si(SiO2 composites,SiO composites and SiOx(0<x<2) composites).The synthesis,morphologies and electrochemical properties of the SiOx-based composites that are applied in LIB are discussed.Finally,the prope rties of several common SiOx-based composites are briefly compared and the challenges faced by SiOx-based composites are highlight.
基金Supported by the National Natural Science Foundation of China(20876145) the Natural Science Foundation of Zhejiang Province(Y4080329)
摘要Supermacroporous composite cryogels embedded with SiO2 nanoparticles were prepared by radical cryogenic copolymerization of the reactive monomer mixture of acrylamide(AAm) and N,N-methylene-bis-acrylamide(MBAAm) containing SiO2 nanoparticles(mass ratios of nanoparticles to the monomer AAm from 0.01 to 0.08) under the freezing-temperature variation condition in glass columns.The properties of these composite cryogels were measured.The height equivalent to theoretical plate(HETP) of the cryogel beds at different liquid flow rates was determined by residence time distribution(RTD) using tracer pulse-response method.The composite cryogel matrix embedded with the mass fraction of SiO2 nanoparticles of 0.02 presented the best properties and was employed in the following graft polymerization.Chromatographic process of lysozyme in the composite cryogel grafted with 2-acrylamido-2-methyl-1-propanesulfonic acid(AMPSA) was carried out to evaluate the protein breakthrough and elution characteristics.The chromatography can be carried out at relatively high superficial velocity,i.e.,15 cm·min-1,indicating the satisfactory mechanical strength due to the embedded nanoparticles.