In order to fabricate highly-conductive glass fibers using graphene as multi-functional coatings, we reported the preparation of graphene-coated glass fibers with high electrical conductivity through solgel and dip-co...In order to fabricate highly-conductive glass fibers using graphene as multi-functional coatings, we reported the preparation of graphene-coated glass fibers with high electrical conductivity through solgel and dip-coating technique in a simple way. Graphene oxide (GO) was partially reduced to graphene hydrosol, and then glass fibers were dipped and coated with the reduced GO (rGO). After repeated solgel and dip-coating treatment, the glass fibers were fully covered with rGO coatings, and consequently exhibited increased hydrophobicity and high electrical conductivity. The graphene-coated fibers exhibited good electrical conductivity of 24.9 S/cm, being higher than that of other nanocarbon-coated fibers and commercial carbon fibers, which is mainly attributed to the high intrinsic electrical conductivity of rGO and full coverage of fiber surfaces. The wettability and electrical conductivity of the coated fibers strongly depended on the dip-coating times and coating thickness, which is closely associated with coverage degree and compact structure of the graphene coatings. By virtue of high conductivity and easy operation, the graphene-coated glass fibers have great potential to be used as flexible conductive wires, highly-sensitive sensors, and multi-functional fibers in many fields.展开更多
This paper investigates the frictional adhesive contact of a rigid,electrically/magnetically conductive spherical indenter sliding past a multiferroic coating deposed onto a rigid substrate,based on the hybrid element...This paper investigates the frictional adhesive contact of a rigid,electrically/magnetically conductive spherical indenter sliding past a multiferroic coating deposed onto a rigid substrate,based on the hybrid element method.The adhesion behavior is described based on the Maugis-Dugdale model.The adhesion-driven conjugate gradient method is employed to calculate the distribution of unknown pressures,while the discrete convolution-fast Fourier transform is utilized to compute the deformations,surface electric and magnetic potentials as well as the subsurface stresses,electric displacements,and magnetic inductions.The goal of this study is to investigate the influences of adhesion parameter,friction coefficient,coating thickness,and surface electric and magnetic charge densities on contact behaviors,such as contact area and pressures,electric and magnetic potentials,and subsurface stresses.展开更多
Transparent zinc oxide（ZnO） thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations（0.3-1.2 M） using zinc acetate dehydrate [Zn（CH_3COO）_2&...Transparent zinc oxide（ZnO） thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations（0.3-1.2 M） using zinc acetate dehydrate [Zn（CH_3COO）_2·2H_2O] as precursor and isopropanol and monoethanolamine（MEA） as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.展开更多
The mixture of Nano-graphite and organic vehicles doped to Nano-diamond paste. The suitable paste proportion was found. Nano-diamond film (NDF) was prepared by sol-gel coating method on ITO glass at 3000/min. The fiel...The mixture of Nano-graphite and organic vehicles doped to Nano-diamond paste. The suitable paste proportion was found. Nano-diamond film (NDF) was prepared by sol-gel coating method on ITO glass at 3000/min. The field emission characteristics of luminance-current, luminance-voltage and luminance-power of Nano-diamond film were analyzed and tested. Comparing these tested curves, the luminance was well proportional to current was got. Theoretic, the inner resistance of NDF field emission display (FED) consumes electric energy and real voltage change between the cathode and the anode of NDF-FED was very small after electrons emit. So the characteristic of NDF-FED was preferable to describe by luminance-current linear relationship, which was advantageous to device tested and designed.展开更多
Alumina membranes without pinholes and cracks were prepared by the sol-gel process using anunordum aluminium sulphate as the starting material. The effects of different preparing conditions on morphology characteristi...Alumina membranes without pinholes and cracks were prepared by the sol-gel process using anunordum aluminium sulphate as the starting material. The effects of different preparing conditions on morphology characteristics of the membrane were investigated by scanning electron microscopy and 3D rotational microscopy. The preparing conditions include the amounts of drying control chemical additives （DCCA）, sintering procedure and sol-gel concentration. The results showed that PVA is a good crack-preventing reagent and the morphology of supported membranes was affected by ninny factors, including Al2O3 concentration, PVA/Al2O3 ratio, heating rate, membrane thickness and intrinsic defects of the substrate surface.展开更多
In this paper, we conduct research on the high-strength coating preparation methodology based on acid catalytic and Sol-Gel method. This method has been widely used in the preparation of various functional thin film, ...In this paper, we conduct research on the high-strength coating preparation methodology based on acid catalytic and Sol-Gel method. This method has been widely used in the preparation of various functional thin film, film and protective film structure, etc. As a result of sol gel process continuously broaden the application field, this method has been more and more get the favor of people. Compared with other traditional preparation methods of inorganic material, sol-gel process has many characteristics. To adjust the solution acidity and add a small amount of acid or alkali can have the effect of＂ catalyst, its reaction process on sol to get and gel structure may also be affected. Our research analyze the topic theoretically and numerically which is meaningful.展开更多
Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectr...Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy analyses revealed a cracked nodular structure for the cerium-vanadium conversion coating which was mainly composed of O, Ce, V, and Mg atoms. All the cracks in the conversion coating were completely sealed by a thin, compact and defect-free hybrid sol？gel film. Potentiodynamic polarization and electrochemical impedance spectroscopy experiments in Harrison’s solution showed that the cerium-vanadium conversion coating provides minimal protection against corrosion while the composite coating significantly increases the corrosion resistance of the magnesium alloy. Sol-gel film provides protection against corrosion by sealing cracks in the cerium-vanadium conversion coating and acting as a barrier. Scanning electron microscopy analyses after polarization tests confirmed the results obtained by the electrochemical tests.展开更多
The present study aims to develop multilayer barrier-bioactive hybrid sol-gel coatings from a mixture of the silane precursors tetraethylorthosilicate(TEOS)and glycidoxypropyltriethoxysilane(GPTMS)deposited on the Ele...The present study aims to develop multilayer barrier-bioactive hybrid sol-gel coatings from a mixture of the silane precursors tetraethylorthosilicate(TEOS)and glycidoxypropyltriethoxysilane(GPTMS)deposited on the Elektron 21 magnesium alloy.The purpose of the inner layer(barrier coating)was to provide corrosion protection to the magnesium alloy,whereas the outer layer(bioactive coating)was doped with different Ca and Mg contents to produce a bioactive material.The coatings were characterised using scanning electron microscopy(SEM)and their corrosion behaviour was evaluated by anodic polarisation and electrochemical impedance spectroscopy after immersion in simulated body fluid(SBF)at 37±0.5°C.The experimental results showed that the multilayer coatings increased the corrosion resistance of the alloy up to three orders of magnitude during immersion in SBF solution.On the other hand,the presence of Ca and Mg in the bioactive coating promoted the growth of apatite-like phases.However,an increment of salt content favoured the formation of porous coatings,which allowed the access of the electrolyte to the substrate leading to their rapid deterioration.Despite the latter,this research endorses the premise that the TEOS-GPTMS hybrid system represents a promising alternative to produce bifunctional barrier-bioactive coatings.展开更多
Sol-gel process is one of the simplest techniques to manufacture thin films. The quality of the prepared films depends on the parameters of the sol-gel process and the used technique for deposition. A great variety of...Sol-gel process is one of the simplest techniques to manufacture thin films. The quality of the prepared films depends on the parameters of the sol-gel process and the used technique for deposition. A great variety of the sol-gel derived films have been prepared for different applications. We present a review on the sol-gel derived coatings. The description of the process is introduced in details. Different sol-gel deposition techniques are mentioned. The optical applications of the sol-gel derived coatings are reviewed.展开更多
Sol—gel coatings offer a number of advantages over other methods of protection for metallic materials.In the present work,3-mercaptopropyltrimethoxysilane（MPTS） was used as the precursor for sol—gel coating on alu...Sol—gel coatings offer a number of advantages over other methods of protection for metallic materials.In the present work,3-mercaptopropyltrimethoxysilane（MPTS） was used as the precursor for sol—gel coating on aluminium metal.The gelation of MPTS sol—gel was characterized by Fourier transform infrared spectroscopy（FT-IR） studies.The formed film was found to be stable up to 350 ℃ as evident from thermogravimetric analysis.X-ray diffraction study and scanning electron microscopy supported the formation of MPTS coating on aluminium surface while the characterization of the coating was done by FT-IR studies.The corrosion inhibition potential of the sol—gel coatings on metal in 3.5%（w/v） of NaCI solution was assessed as a function of different concentrations of MPTS using electrochemical polarization and impedance measurements.The corrosion inhibition efficiency was found to increase with increasing MPTS concentration.The results of the study unravel the use of MPTS as a precursor in the formation of sol—gel coating over aluminium surface so as to protect the metallic surface from corrosion in neutral environment.展开更多
The continuous rise in turbine inlet temperatures in aero-engines has intensified the need for improved thermal insulation in thermal barrier coatings(TBCs).Traditionally,reducing the thermal conductivity of TBCs has ...The continuous rise in turbine inlet temperatures in aero-engines has intensified the need for improved thermal insulation in thermal barrier coatings(TBCs).Traditionally,reducing the thermal conductivity of TBCs has been the primary strategy to enhance their thermal insulation.Columnar TBCs are generally deemed to have higher thermal conductivity and inferior thermal insulation compared to lamellar TBCs.However,in this study,we demonstrate that under ultra-high temperature conditions(>1300℃),columnar TBCs exhibit superior radiative cooling capabilities due to their higher emissivity in the near-infrared region.This enhanced radiative heat dissipation effectively offsets the limitations of their high thermal conductivity.A novel"blackbody effect"hypothesis is proposed to elucidate this behavior.Finite element simulations quantitatively substantiate this hypothesis,showing strong agreement with experimental observations.These findings offer a groundbreaking perspective:columnar coatings,despite higher thermal conductivity,can narrow the thermal insulation gap with lamellar coatings at ultra-high temperatures through enhanced radiation cooling capabilities.This work provides a new structural strategy for optimizing emissivity and broadens the design framework for next-generation TBCs.展开更多
8-hydroxyquinoline(8-HQ)intercalated layered double hydroxides(LDH)film as underlayer and sol-gel layer was combined for active corrosion protection of the AM60B magnesium alloy.The LDH,LDH/sol-gel,and LDH@HQ/sol-gel ...8-hydroxyquinoline(8-HQ)intercalated layered double hydroxides(LDH)film as underlayer and sol-gel layer was combined for active corrosion protection of the AM60B magnesium alloy.The LDH,LDH/sol-gel,and LDH@HQ/sol-gel coatings were analyzed using the scanning electron microscopy(SEM),field emission scanning electron microscopy(FESEM),energy dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),atomic force microscopy(AFM),and electrochemical impedance spectroscopy(EIS)methods.The SEM images showed that the surface was entirely coated by the LDH film composed of vertically-grown nanosheets.The same morphology was observed for the LDH/sol-gel and LDH@HQ/sol-gel coatings.Also,almost the same topography was observed for both composite coatings except that the LDH@HQ/sol-gel coating had relatively higher surface roughness.Although the LDH film had the same impedance behavior as the alloy sample in 3.5wt%NaCl solution,its corrosion resistance was much higher,which could be due to its barrier properties as well as to the trap-ping of the chloride ions.Similar to the LDH film,the corrosion resistance of the LDH/sol-gel composite diminished with increasing the ex-posure time.However,its values were much higher than that of the LDH film,which was mainly related to the sealing of the solution path-ways.The LDH@HQ/sol-gel composite showed much better anti-corrosion properties than the LDH/sol-gel coating due to the adsorption of the 8-HQ on the damaged areas through the complexation.展开更多
In this work, it is presented the synthesis and characterization of transparent and colorless organic-inorganic hybrid anti-graffiti protective materials obtained by sol-gel method. This type of materials is based on ...In this work, it is presented the synthesis and characterization of transparent and colorless organic-inorganic hybrid anti-graffiti protective materials obtained by sol-gel method. This type of materials is based on MTES （methyltriethoxysilane）, TPOZ （tetrapropoxide of zirconium） and PDMS （polydimethylsiloxane）. The synthesis has been carried out at 25, 35 and 45 ℃ in order to evaluate the role of temperature in the structure, microstructure and anti-graffiti behavior as well. The incorporation of zirconium within the organic modified silica network, of sols after being gelled and dried, is evident by a shoulder which increased with temperature situated at 950 cml （Si-O-Zr bonds）, and it is homogenously dispersed inside the matrix avoiding the formation of large ZrO2 precipitates. As the temperature increases, the hydrolysis and condensation reactions occur in more extension and thus, the obtained sols are more cross-linked and present more Si-O-Zr linkages. The promising anti-graffiti beha＇4ior of the protectNe hybrids was qualitatively determined being the spot removal higher than 90%.展开更多
Methods for evaluating the resistance to cathodic disbondment （RCD） of anti-corrosion coatings on buried pipelines were reviewed. It is obvious that these traditional cathodic disbondment tests （CDT） have some dis...Methods for evaluating the resistance to cathodic disbondment （RCD） of anti-corrosion coatings on buried pipelines were reviewed. It is obvious that these traditional cathodic disbondment tests （CDT） have some disadvantages and the evaluated results are only simple figures and always rely on the subjective experience of the operator. A new electrochemical method for evaluating the RCD of coatings, that is, the potentiostatic evaluation method （PEM）, was developed and studied. During potentiostatic anodic polarization testing, the changes of stable polarization current of specimens before and after cathodic disbonding （CD） were measured, and the degree of cathodic disbondment of the coating was quantitatively evaluated, among which the equivalent cathodic disbonded distance AD was suggested as a parameter for evaluating the RCD. A series of testing parameters of the PEM were determined in these experiments.展开更多
A numerical method has been developed to extract the composition-dependent interdiffusivity from the concentration profiles in the aluminide coating prepared by pack cementation. The procedure is based on the classic ...A numerical method has been developed to extract the composition-dependent interdiffusivity from the concentration profiles in the aluminide coating prepared by pack cementation. The procedure is based on the classic finite difference method (FDM). In order to simplify the model, effect of some alloying elements on interdiffusivity can be negligible. Calculated results indicate the interdiffusivity in aluminide coating strongly depends on the composition and give the formulas used to calculate interdiffusivity at 850, 950 and 1050癈. The effect on interdiffusivity is briefly discussed.展开更多
zirconia-based nanostructured coatings were deposited on AA2024 to improve the corrosion resistance properties. Three different nanostructured coatings, namely, zirconia–benzotriazole, zirconia–alumina–benzotriazol...zirconia-based nanostructured coatings were deposited on AA2024 to improve the corrosion resistance properties. Three different nanostructured coatings, namely, zirconia–benzotriazole, zirconia–alumina–benzotriazole, and zirconia–yttria–benzotriazole, were applied on AA2024 via a sol–gel method using the dip-coating technique. Next, the coatings were annealed at 150°C after each dipping period. The phases and morphologies of the coatings were investigated using grazing incidence X-ray diffraction(GIXRD), Fourier transform infrared spectroscopy(FT-IR), field emission scanning electron microscopy(FESEM), and atomic force microscopy(AFM). The corrosion properties were evaluated using electrochemical methods, including polarization and electrochemical impedance techniques in 3.5 wt% NaCl solution. The obtained results confirm the formation of homogeneous and crack free zirconia-benzotriazole-based nanostructured coatings. The average roughness values for zirconia-benzotriazole, zirconia-alumina-benzotriazole, and zirconia-yttria-benzotriazole nanostructured coatings were 30, 8, and 6 nm, respectively. The presence of alumina as a stabilizer on zirconia coating was found to have a beneficial impact on the stability of the corrosion resistance for different immersion times. In fact, the addition of alumina resulted in the dominance of the healing behavior in competition with the corrosion process of zirconia-benzotriazole nanostructured coating.展开更多
An Al_(2)O_(3)coating was prepared from aluminum isopropoxide as precursor on tungsten substrate.The dependences of crystalline and phase in Al_(2)O_(3)coating on temperature were studied.The results show the coatings...An Al_(2)O_(3)coating was prepared from aluminum isopropoxide as precursor on tungsten substrate.The dependences of crystalline and phase in Al_(2)O_(3)coating on temperature were studied.The results show the coatings being compact,uniform and crack-free can be obtained by suitable experiment.The main phase of coating isα-Al_(2)O_(3).Compared to the uncoated specimens,the ones with coatings synthesized by sol-gel process provide excellent oxidation resistance at high temperature.展开更多
Ti6Al4V substrates were anodized in a 0.5 mol/L H_2SO_4 solution at applied voltages of 90-140 V.A hydroxyapatite-titanium oxide（HA-TiO2）coating was then deposited on the anodized Ti6Al4 V substrates via a hydrother...Ti6Al4V substrates were anodized in a 0.5 mol/L H_2SO_4 solution at applied voltages of 90-140 V.A hydroxyapatite-titanium oxide（HA-TiO2）coating was then deposited on the anodized Ti6Al4 V substrates via a hydrothermal-electrochemicalmethod at a constant current.The obtained films and coatings were characterized by X-ray diffraction,scanning electron microscopy,energy-dispersive X-ray spectroscopy,and Fourier-transform infrared spectrometry.The microstructures of the porous films on the Ti6Al4 V substrates were studied to investigate the effect of the anodizing voltage on the phase and morphology of the HATiO_2 coating.The results indicated that both the phase composition and the morphology of the coatings were significantly influenced by changes in the anodizing voltage.HA-TiO_2 was directly precipitated onto the surface of the substrate when the applied voltage was between 110 and 140 V.The coatings had a gradient structure and the HA exhibited both needle-like and cotton-like structures.The amount of cotton-like HA structures decreased with an increase in voltage from 90 to 120 V,and then increased slightly when the voltage was higher than 120 V.The orientation index of the（002）plane of the coating was at a minimum when the Ti6Al4 V substrate was pretreated at 120 V.展开更多
ZnO thin films co-doped with A1 and Sb with different concentrations and a fixed molar ratio of AlCl3 to SbCl3 at 1：2, are prepared by a sol-gel spin-coating method on glass annealed at 550 ℃ for 2 h in air. The x-r...ZnO thin films co-doped with A1 and Sb with different concentrations and a fixed molar ratio of AlCl3 to SbCl3 at 1：2, are prepared by a sol-gel spin-coating method on glass annealed at 550 ℃ for 2 h in air. The x-ray diffraction results confirm that the ZnO thin films co-doped with Al distortion, and the biaxial stresses are 1.03× 10^8. 3.26× 10^8 and Sb are of wurtzite hexagonal ZnO with a very small 5.23 × 10^8, and 6.97× 10^8 Pa, corresponding to those of the ZnO thin films co-doped with Al and Sb in concentrations of 1.5, 3.0, 4.5, 6.0 at% respectively. The optical properties reveal that the ZnO thin films co-doped with Al and Sb have obviously enhanced transmittance in the visible region. The electrical properties show that ZnO thin film co-doped with Al and Sb in a concentration of 1.5 at% has a lowest resistivity of 2.5 Ω·cm.展开更多
In the present study, niobium-doped indium oxide thin films were prepared by sol-gel spin coating technique. The effects of different Nb-doping contents on structural, morphological, optical, and electrical properties...In the present study, niobium-doped indium oxide thin films were prepared by sol-gel spin coating technique. The effects of different Nb-doping contents on structural, morphological, optical, and electrical properties of the films were characterized by means of X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, atomic force microscopy （AFM）, UV-Vis spectroscopy, and four point probe methods. XRD analysis confirmed the formation of cubic bixbyite structure of In203 with a small shift in major peak position toward lower angles with addition of Nb. FESEM micrographs show that grain size decreased with increasing the Nb-doping content. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum electrical resistivity of 119.4 × 10^-3 Ω cm and an average optical transmittance of 85% in the visible region with a band gap of 3.37 eV were achieved for the films doped with Nb-doping content of 3 at.%. AFM studies show that addition of Nb at optimum content leads to the formation of compact films with smooth surface and less average roughness compared with the prepared ln2O3 films.展开更多
基金financial supports from the National Natural Science Foundation of China (No. 51802317)Department of Science and Technology of Shenyang City (No. 17-231-1-66)Shenyang National Laboratory for Materials Science (No. 2017RP11)
文摘In order to fabricate highly-conductive glass fibers using graphene as multi-functional coatings, we reported the preparation of graphene-coated glass fibers with high electrical conductivity through solgel and dip-coating technique in a simple way. Graphene oxide (GO) was partially reduced to graphene hydrosol, and then glass fibers were dipped and coated with the reduced GO (rGO). After repeated solgel and dip-coating treatment, the glass fibers were fully covered with rGO coatings, and consequently exhibited increased hydrophobicity and high electrical conductivity. The graphene-coated fibers exhibited good electrical conductivity of 24.9 S/cm, being higher than that of other nanocarbon-coated fibers and commercial carbon fibers, which is mainly attributed to the high intrinsic electrical conductivity of rGO and full coverage of fiber surfaces. The wettability and electrical conductivity of the coated fibers strongly depended on the dip-coating times and coating thickness, which is closely associated with coverage degree and compact structure of the graphene coatings. By virtue of high conductivity and easy operation, the graphene-coated glass fibers have great potential to be used as flexible conductive wires, highly-sensitive sensors, and multi-functional fibers in many fields.
基金support from the National Natural Science Foundation of China(12102085)the Postdoctoral Science Foundation of China(2023M730504)+2 种基金the Sichuan Province Regional Innovation and Cooperation Project(2024YFHZ0210)supported by the European Union-NextGenerationEU through the Italian Ministry of University and Research under the following programs:(NM)PRIN2022(Projects of Relevant National Interest)grant no.2022SJ8HTC-Electroactive Gripper for Micro-Object Manipulation(ELFIN)(NM)PRIN2022 PNRR(Projects of Relevant National Interest)grant no.P2022MAZHX-Tribological Modeling for Sustainable Design of Industrial Frictional Interfaces(TRIBOSCORE).
文摘This paper investigates the frictional adhesive contact of a rigid,electrically/magnetically conductive spherical indenter sliding past a multiferroic coating deposed onto a rigid substrate,based on the hybrid element method.The adhesion behavior is described based on the Maugis-Dugdale model.The adhesion-driven conjugate gradient method is employed to calculate the distribution of unknown pressures,while the discrete convolution-fast Fourier transform is utilized to compute the deformations,surface electric and magnetic potentials as well as the subsurface stresses,electric displacements,and magnetic inductions.The goal of this study is to investigate the influences of adhesion parameter,friction coefficient,coating thickness,and surface electric and magnetic charge densities on contact behaviors,such as contact area and pressures,electric and magnetic potentials,and subsurface stresses.
文摘Transparent zinc oxide（ZnO） thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations（0.3-1.2 M） using zinc acetate dehydrate [Zn（CH_3COO）_2·2H_2O] as precursor and isopropanol and monoethanolamine（MEA） as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.
文摘The mixture of Nano-graphite and organic vehicles doped to Nano-diamond paste. The suitable paste proportion was found. Nano-diamond film (NDF) was prepared by sol-gel coating method on ITO glass at 3000/min. The field emission characteristics of luminance-current, luminance-voltage and luminance-power of Nano-diamond film were analyzed and tested. Comparing these tested curves, the luminance was well proportional to current was got. Theoretic, the inner resistance of NDF field emission display (FED) consumes electric energy and real voltage change between the cathode and the anode of NDF-FED was very small after electrons emit. So the characteristic of NDF-FED was preferable to describe by luminance-current linear relationship, which was advantageous to device tested and designed.
基金Project supported by National Natural Science Foundation ofChina (Grant No .20373040) Science Foundation of Science andTechnology Commission of Zhejiang Province ( Grant No .0252nm101) Science Foundation of Shanghai MunicipalCommission of Science and Technology (Grant No .0452nm019)
文摘Alumina membranes without pinholes and cracks were prepared by the sol-gel process using anunordum aluminium sulphate as the starting material. The effects of different preparing conditions on morphology characteristics of the membrane were investigated by scanning electron microscopy and 3D rotational microscopy. The preparing conditions include the amounts of drying control chemical additives （DCCA）, sintering procedure and sol-gel concentration. The results showed that PVA is a good crack-preventing reagent and the morphology of supported membranes was affected by ninny factors, including Al2O3 concentration, PVA/Al2O3 ratio, heating rate, membrane thickness and intrinsic defects of the substrate surface.
文摘In this paper, we conduct research on the high-strength coating preparation methodology based on acid catalytic and Sol-Gel method. This method has been widely used in the preparation of various functional thin film, film and protective film structure, etc. As a result of sol gel process continuously broaden the application field, this method has been more and more get the favor of people. Compared with other traditional preparation methods of inorganic material, sol-gel process has many characteristics. To adjust the solution acidity and add a small amount of acid or alkali can have the effect of＂ catalyst, its reaction process on sol to get and gel structure may also be affected. Our research analyze the topic theoretically and numerically which is meaningful.
文摘Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy analyses revealed a cracked nodular structure for the cerium-vanadium conversion coating which was mainly composed of O, Ce, V, and Mg atoms. All the cracks in the conversion coating were completely sealed by a thin, compact and defect-free hybrid sol？gel film. Potentiodynamic polarization and electrochemical impedance spectroscopy experiments in Harrison’s solution showed that the cerium-vanadium conversion coating provides minimal protection against corrosion while the composite coating significantly increases the corrosion resistance of the magnesium alloy. Sol-gel film provides protection against corrosion by sealing cracks in the cerium-vanadium conversion coating and acting as a barrier. Scanning electron microscopy analyses after polarization tests confirmed the results obtained by the electrochemical tests.
基金the Vicerrectorìa de Investigación y Extension of the Universidad Industrial de Santander,Colombia(grant number 2508)for the financial support of the present work
文摘The present study aims to develop multilayer barrier-bioactive hybrid sol-gel coatings from a mixture of the silane precursors tetraethylorthosilicate(TEOS)and glycidoxypropyltriethoxysilane(GPTMS)deposited on the Elektron 21 magnesium alloy.The purpose of the inner layer(barrier coating)was to provide corrosion protection to the magnesium alloy,whereas the outer layer(bioactive coating)was doped with different Ca and Mg contents to produce a bioactive material.The coatings were characterised using scanning electron microscopy(SEM)and their corrosion behaviour was evaluated by anodic polarisation and electrochemical impedance spectroscopy after immersion in simulated body fluid(SBF)at 37±0.5°C.The experimental results showed that the multilayer coatings increased the corrosion resistance of the alloy up to three orders of magnitude during immersion in SBF solution.On the other hand,the presence of Ca and Mg in the bioactive coating promoted the growth of apatite-like phases.However,an increment of salt content favoured the formation of porous coatings,which allowed the access of the electrolyte to the substrate leading to their rapid deterioration.Despite the latter,this research endorses the premise that the TEOS-GPTMS hybrid system represents a promising alternative to produce bifunctional barrier-bioactive coatings.
基金we are very grateful to the National Natural Scieneo Founda-tion of China(No.69978017,59802007)Shanghai Edu-cation Comrnittee(No.JW99 TJ-03)for their help and 6nancialsupports.
文摘Sol-gel process is one of the simplest techniques to manufacture thin films. The quality of the prepared films depends on the parameters of the sol-gel process and the used technique for deposition. A great variety of the sol-gel derived films have been prepared for different applications. We present a review on the sol-gel derived coatings. The description of the process is introduced in details. Different sol-gel deposition techniques are mentioned. The optical applications of the sol-gel derived coatings are reviewed.
基金BRNS, Department of Atomic Energy,Mumbai,for providing financial assistance to carry out the study
文摘Sol—gel coatings offer a number of advantages over other methods of protection for metallic materials.In the present work,3-mercaptopropyltrimethoxysilane（MPTS） was used as the precursor for sol—gel coating on aluminium metal.The gelation of MPTS sol—gel was characterized by Fourier transform infrared spectroscopy（FT-IR） studies.The formed film was found to be stable up to 350 ℃ as evident from thermogravimetric analysis.X-ray diffraction study and scanning electron microscopy supported the formation of MPTS coating on aluminium surface while the characterization of the coating was done by FT-IR studies.The corrosion inhibition potential of the sol—gel coatings on metal in 3.5%（w/v） of NaCI solution was assessed as a function of different concentrations of MPTS using electrochemical polarization and impedance measurements.The corrosion inhibition efficiency was found to increase with increasing MPTS concentration.The results of the study unravel the use of MPTS as a precursor in the formation of sol—gel coating over aluminium surface so as to protect the metallic surface from corrosion in neutral environment.
基金financially supported by the National Key Research and Development Program of China(No.2022YFB3504902)the Natural Science Foundation of China(NSFC)(Nos.U21B2052 and 52102057)the Science Center for Gas Turbine Project(No.P2023-C-Ⅳ-002-001).
文摘The continuous rise in turbine inlet temperatures in aero-engines has intensified the need for improved thermal insulation in thermal barrier coatings(TBCs).Traditionally,reducing the thermal conductivity of TBCs has been the primary strategy to enhance their thermal insulation.Columnar TBCs are generally deemed to have higher thermal conductivity and inferior thermal insulation compared to lamellar TBCs.However,in this study,we demonstrate that under ultra-high temperature conditions(>1300℃),columnar TBCs exhibit superior radiative cooling capabilities due to their higher emissivity in the near-infrared region.This enhanced radiative heat dissipation effectively offsets the limitations of their high thermal conductivity.A novel"blackbody effect"hypothesis is proposed to elucidate this behavior.Finite element simulations quantitatively substantiate this hypothesis,showing strong agreement with experimental observations.These findings offer a groundbreaking perspective:columnar coatings,despite higher thermal conductivity,can narrow the thermal insulation gap with lamellar coatings at ultra-high temperatures through enhanced radiation cooling capabilities.This work provides a new structural strategy for optimizing emissivity and broadens the design framework for next-generation TBCs.
文摘8-hydroxyquinoline(8-HQ)intercalated layered double hydroxides(LDH)film as underlayer and sol-gel layer was combined for active corrosion protection of the AM60B magnesium alloy.The LDH,LDH/sol-gel,and LDH@HQ/sol-gel coatings were analyzed using the scanning electron microscopy(SEM),field emission scanning electron microscopy(FESEM),energy dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),atomic force microscopy(AFM),and electrochemical impedance spectroscopy(EIS)methods.The SEM images showed that the surface was entirely coated by the LDH film composed of vertically-grown nanosheets.The same morphology was observed for the LDH/sol-gel and LDH@HQ/sol-gel coatings.Also,almost the same topography was observed for both composite coatings except that the LDH@HQ/sol-gel coating had relatively higher surface roughness.Although the LDH film had the same impedance behavior as the alloy sample in 3.5wt%NaCl solution,its corrosion resistance was much higher,which could be due to its barrier properties as well as to the trap-ping of the chloride ions.Similar to the LDH film,the corrosion resistance of the LDH/sol-gel composite diminished with increasing the ex-posure time.However,its values were much higher than that of the LDH film,which was mainly related to the sealing of the solution path-ways.The LDH@HQ/sol-gel composite showed much better anti-corrosion properties than the LDH/sol-gel coating due to the adsorption of the 8-HQ on the damaged areas through the complexation.
文摘In this work, it is presented the synthesis and characterization of transparent and colorless organic-inorganic hybrid anti-graffiti protective materials obtained by sol-gel method. This type of materials is based on MTES （methyltriethoxysilane）, TPOZ （tetrapropoxide of zirconium） and PDMS （polydimethylsiloxane）. The synthesis has been carried out at 25, 35 and 45 ℃ in order to evaluate the role of temperature in the structure, microstructure and anti-graffiti behavior as well. The incorporation of zirconium within the organic modified silica network, of sols after being gelled and dried, is evident by a shoulder which increased with temperature situated at 950 cml （Si-O-Zr bonds）, and it is homogenously dispersed inside the matrix avoiding the formation of large ZrO2 precipitates. As the temperature increases, the hydrolysis and condensation reactions occur in more extension and thus, the obtained sols are more cross-linked and present more Si-O-Zr linkages. The promising anti-graffiti beha＇4ior of the protectNe hybrids was qualitatively determined being the spot removal higher than 90%.
基金This work is financially supported by the National Natural Science Foundation of China (No.2992021).
文摘Methods for evaluating the resistance to cathodic disbondment （RCD） of anti-corrosion coatings on buried pipelines were reviewed. It is obvious that these traditional cathodic disbondment tests （CDT） have some disadvantages and the evaluated results are only simple figures and always rely on the subjective experience of the operator. A new electrochemical method for evaluating the RCD of coatings, that is, the potentiostatic evaluation method （PEM）, was developed and studied. During potentiostatic anodic polarization testing, the changes of stable polarization current of specimens before and after cathodic disbonding （CD） were measured, and the degree of cathodic disbondment of the coating was quantitatively evaluated, among which the equivalent cathodic disbonded distance AD was suggested as a parameter for evaluating the RCD. A series of testing parameters of the PEM were determined in these experiments.
文摘A numerical method has been developed to extract the composition-dependent interdiffusivity from the concentration profiles in the aluminide coating prepared by pack cementation. The procedure is based on the classic finite difference method (FDM). In order to simplify the model, effect of some alloying elements on interdiffusivity can be negligible. Calculated results indicate the interdiffusivity in aluminide coating strongly depends on the composition and give the formulas used to calculate interdiffusivity at 850, 950 and 1050癈. The effect on interdiffusivity is briefly discussed.
文摘zirconia-based nanostructured coatings were deposited on AA2024 to improve the corrosion resistance properties. Three different nanostructured coatings, namely, zirconia–benzotriazole, zirconia–alumina–benzotriazole, and zirconia–yttria–benzotriazole, were applied on AA2024 via a sol–gel method using the dip-coating technique. Next, the coatings were annealed at 150°C after each dipping period. The phases and morphologies of the coatings were investigated using grazing incidence X-ray diffraction(GIXRD), Fourier transform infrared spectroscopy(FT-IR), field emission scanning electron microscopy(FESEM), and atomic force microscopy(AFM). The corrosion properties were evaluated using electrochemical methods, including polarization and electrochemical impedance techniques in 3.5 wt% NaCl solution. The obtained results confirm the formation of homogeneous and crack free zirconia-benzotriazole-based nanostructured coatings. The average roughness values for zirconia-benzotriazole, zirconia-alumina-benzotriazole, and zirconia-yttria-benzotriazole nanostructured coatings were 30, 8, and 6 nm, respectively. The presence of alumina as a stabilizer on zirconia coating was found to have a beneficial impact on the stability of the corrosion resistance for different immersion times. In fact, the addition of alumina resulted in the dominance of the healing behavior in competition with the corrosion process of zirconia-benzotriazole nanostructured coating.
基金Beijing Municipal Commission of Education(0090005466010)
文摘An Al_(2)O_(3)coating was prepared from aluminum isopropoxide as precursor on tungsten substrate.The dependences of crystalline and phase in Al_(2)O_(3)coating on temperature were studied.The results show the coatings being compact,uniform and crack-free can be obtained by suitable experiment.The main phase of coating isα-Al_(2)O_(3).Compared to the uncoated specimens,the ones with coatings synthesized by sol-gel process provide excellent oxidation resistance at high temperature.
基金Funded in part by the Key Laboratory of Inorginic Coating MaterialsChinese Academy of Sciences(No.KLICM-2014-11)the Shanghai Municipal Natural Science Foundation Sponsored by Shanghai Municipal Science and Technology Commissions(No.15ZR1428300)
文摘Ti6Al4V substrates were anodized in a 0.5 mol/L H_2SO_4 solution at applied voltages of 90-140 V.A hydroxyapatite-titanium oxide（HA-TiO2）coating was then deposited on the anodized Ti6Al4 V substrates via a hydrothermal-electrochemicalmethod at a constant current.The obtained films and coatings were characterized by X-ray diffraction,scanning electron microscopy,energy-dispersive X-ray spectroscopy,and Fourier-transform infrared spectrometry.The microstructures of the porous films on the Ti6Al4 V substrates were studied to investigate the effect of the anodizing voltage on the phase and morphology of the HATiO_2 coating.The results indicated that both the phase composition and the morphology of the coatings were significantly influenced by changes in the anodizing voltage.HA-TiO_2 was directly precipitated onto the surface of the substrate when the applied voltage was between 110 and 140 V.The coatings had a gradient structure and the HA exhibited both needle-like and cotton-like structures.The amount of cotton-like HA structures decreased with an increase in voltage from 90 to 120 V,and then increased slightly when the voltage was higher than 120 V.The orientation index of the（002）plane of the coating was at a minimum when the Ti6Al4 V substrate was pretreated at 120 V.
基金Project supported by the Innovation Foundation of Beijing University of Aeronautics and Astronautics for PhD Graduates, China (Grant No. 292122)the Equipment Research Foundation of China (Grant No. 373974)
文摘ZnO thin films co-doped with A1 and Sb with different concentrations and a fixed molar ratio of AlCl3 to SbCl3 at 1：2, are prepared by a sol-gel spin-coating method on glass annealed at 550 ℃ for 2 h in air. The x-ray diffraction results confirm that the ZnO thin films co-doped with Al distortion, and the biaxial stresses are 1.03× 10^8. 3.26× 10^8 and Sb are of wurtzite hexagonal ZnO with a very small 5.23 × 10^8, and 6.97× 10^8 Pa, corresponding to those of the ZnO thin films co-doped with Al and Sb in concentrations of 1.5, 3.0, 4.5, 6.0 at% respectively. The optical properties reveal that the ZnO thin films co-doped with Al and Sb have obviously enhanced transmittance in the visible region. The electrical properties show that ZnO thin film co-doped with Al and Sb in a concentration of 1.5 at% has a lowest resistivity of 2.5 Ω·cm.
基金Iran Initiative Nanotechnology Council for partially supporting this workMahar Fan Abzar Co.for AFM spectroscopy results
文摘In the present study, niobium-doped indium oxide thin films were prepared by sol-gel spin coating technique. The effects of different Nb-doping contents on structural, morphological, optical, and electrical properties of the films were characterized by means of X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, atomic force microscopy （AFM）, UV-Vis spectroscopy, and four point probe methods. XRD analysis confirmed the formation of cubic bixbyite structure of In203 with a small shift in major peak position toward lower angles with addition of Nb. FESEM micrographs show that grain size decreased with increasing the Nb-doping content. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum electrical resistivity of 119.4 × 10^-3 Ω cm and an average optical transmittance of 85% in the visible region with a band gap of 3.37 eV were achieved for the films doped with Nb-doping content of 3 at.%. AFM studies show that addition of Nb at optimum content leads to the formation of compact films with smooth surface and less average roughness compared with the prepared ln2O3 films.
