Integrating titanium-based implants with the surrounding bone tissue remains challenging.This study aims to explore the impact of different anodization voltages(20−80 V)on the surface topography of two-phase(α/β)Ti ...Integrating titanium-based implants with the surrounding bone tissue remains challenging.This study aims to explore the impact of different anodization voltages(20−80 V)on the surface topography of two-phase(α/β)Ti alloys and to produce TiO_(2) films with enhanced bone formation abilities.Scanning electron microscopy coupled with energy dispersive spectroscopy(SEM−EDS)and atomic force microscopy(AFM)were applied to investigate the morphological,chemical,and surface topography of the prepared alloys and to confirm the growth of hydroxyapatite(HA)on their surfaces.Results disclosed that the surface roughness of TiO_(2) films formed on Ti−6Al−7Nb alloys was superior to that of Ti−6Al−4V alloys.Ti−6Al−7Nb alloy anodized at 80 V had the highest yields of HA after immersion in simulated body fluid with enhanced HA surface coverage.The developed HA layer had a mean thickness of(128.38±18.13)μm,suggesting its potential use as an orthopedic implantable material due to its promising bone integration and,hence,remarkable stability inside the human body.展开更多
Both Ti foil and porous Ti were anodized in 0.5%HF and in ethylene glycol electrolyte containing 0.5%NH4F(mass fraction) separately. The results show that TiO2 nanotubes can be formed on Ti foil by both processes, whe...Both Ti foil and porous Ti were anodized in 0.5%HF and in ethylene glycol electrolyte containing 0.5%NH4F(mass fraction) separately. The results show that TiO2 nanotubes can be formed on Ti foil by both processes, whereas TiO2 nanotubes can be formed on porous Ti only in the second process. The overhigh current density led to the failure of the formation nanotubes on porous Ti in 0.5%HF electrolyte. TiO2 nanotubes were characterized by SEM and XRD. TiO2 nanotubes on porous Ti were thinner than those on Ti foil. Anatase was formed when TiO2 nanotubes were annealed at 400 °C and fully turned into rutile at 700 °C. To obtain good photodegradation, the optimal heat treatment temperature of TiO2 nanotubes was 450 °C. The porosity of the substrates influenced photodegradation properties. TiO2 nanotubes on porous Ti with 60% porosity had the best photodegradation.展开更多
A facile route for preparation of gradient wettability surface on copper substrate with contact angle changing from 90.3°to4.2°was developed.The Cu（OH）2 nanoribbon arrays were electrochemically deposited o...A facile route for preparation of gradient wettability surface on copper substrate with contact angle changing from 90.3°to4.2°was developed.The Cu（OH）2 nanoribbon arrays were electrochemically deposited on copper foil via a modified anodization technology,and the growth degree and density of the Cu（OH）2 arrays may be controlled varying with position along the substrate by slowly adding aqueous solution of KOH into the two-electrode cell of an anodization system to form the gradient surface.The prepared surface was water resistant and thermal stable,which could keep its gradient wetting property after being immersed in water bath at 100℃ for 10 h.The results of scanning electron microscopy（SEM）,X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS） demonstrate that the distribution of Cu（OH）2 nanoribbon arrays on copper surface are responsible for the gradient wettability.展开更多
To shield TiAl alloy from hot corrosion attack,a compact protective coating was fabricated by the combination of aluminizing,anodization and pre-oxidation.The hot corrosion behavior of the coated-TiAl specimen was inv...To shield TiAl alloy from hot corrosion attack,a compact protective coating was fabricated by the combination of aluminizing,anodization and pre-oxidation.The hot corrosion behavior of the coated-TiAl specimen was investigated in the mixture salt consisting of 75 wt.%Na2SO4 and 25 wt.%NaCl at 700°C.Results indicated that the anodization and pre-oxidation were beneficial to the generation of Al2O3 layer,which could act as a diffusion barrier to prevent the molten salts and oxygen from diffusing into the alloy during exposure to a hot corrosion environment while the aluminizing coating could provide sufficient aluminum source to support the continuous formation of Al2O3 layer.Moreover,the internal stress of the coating was reduced due to the formation of a gradient coating consisting of TiAl3 and TiAl2.展开更多
Self-organized titanium dioxide(TiO_(2))nanotubes,which are prepared by electrochemical anodizing,have been widely researched as promising anodes for Liion batteries.Both nanotubular morphology and bulk structure of T...Self-organized titanium dioxide(TiO_(2))nanotubes,which are prepared by electrochemical anodizing,have been widely researched as promising anodes for Liion batteries.Both nanotubular morphology and bulk structure of TiO_(2)nanotubes can be easily changed by adjusting the anodizing and annealing parameters.This is provided to investigate different phenomena by selectively adjusting a specific parameter of the Li^(+)insertion mechanism.In this paper,we reviewed how the morphology and crystallography of TiO_(2)nano tubes influence the electrochemical performance of Li^(+)batteries.In particular,electrochemical performances of amorphous and anatase titanium dioxide nanotube anodes were compared in detail.As we all know,TiO_(2)nanotube anodes have the advantages of nontoxicity,good stability,high safety and large specific surface area,in lithium-ion batteries.However,they suffer from poor electronic conductivity,inferior ion diffusivity and low theoretical capacity(335 mAh·g^(-1)),which limit their practical application.Generally,there are two ways to overcome the shortcomings of titanium dioxide nanotube anodes,including doping and synthesis composites.The achievements and existing problems associated with doped TiO_(2)nanotube anodes and composite material anodes are summarized in the present review.Based on the analysis of lithium insertion mechanism of titanium dioxide nanotube electrodes,the prospects and possible research directions of TiO_(2)anodes in lithiumion batteries are discussed.展开更多
Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer,but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer ...Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer,but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer and antibacterial properties to inhibit cancer/bacteria invasion.The present work aims at endowing the NiTi alloy with anticancer and antibacterial abilities by surface modification.Ni–Ti–O nanoporous layers with different thicknesses were prepared on NiTi by anodization,and biological experiments were conducted to evaluate the effects on gram-positive Staphylococcus aureus,human lung epithelial cancer cells(A549),as well as human endothelial cells(EA.hy926).The nanoporous layer with a thickness of 10.1 lm inhibits growth of cancer cells and kill bacteria but shows little adverse effects on normal cells.Such selectivity is related to the larger amount of Ni ions leached from the sample in the acidic microenvironment of cancer cells in comparison with normal cells.The Ni–Ti–O nanoporous layers are promising as coatings on NiTi stents to prevent re-obstruction after surgery.展开更多
Well crystallized niobium-doped TiO; nanotube arrays （TiNbO-NT） were successfully synthesized via the anodization of titanium/niobium alloy sheets, followed with a heat treatment at 550 ℃ for 2 h. Morphology analys...Well crystallized niobium-doped TiO; nanotube arrays （TiNbO-NT） were successfully synthesized via the anodization of titanium/niobium alloy sheets, followed with a heat treatment at 550 ℃ for 2 h. Morphology analysis results demonstrated that both the titanium/niobium alloy microstructure and the dissolution strength of electrolyte played major roles in the formation of nanotube structure. A single-phase microstructure was more favorable to the formation of uniform nanotube arrays, while modulating the dissolution strength of electrolyte was required to obtain nanotube arrays from the alloys with multi-phase microstructures. X-ray diffraction （XRD） and X-ray photoelectron （XPS） analysis results clearly demonstrated that niobium dopants （Nb^5＋） were successfully doped into TiO2 anatase lattice by substituting Ti^4＋ in this approach.展开更多
Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization. The effects of current density （CD） on microhardness, structur...Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization. The effects of current density （CD） on microhardness, structure, composition and surface topography of the oxide layer formed at various CDs （0.1-0.25 A/cm^2） have been studied. Crystalline coatings formed at 0.25 A/cm^2 have been （width 95 nm） observed with a relatively uniform distribution confirmed by scanning electron microscopy. Additionally, the average microhardness value of ceramic nanocomposite coatings fabricated from lithium sulphate-zirconium silicate bath is approximately 8.5 times higher than that of the as-received aluminium. The surface statistics of the coatings is discussed in detail to explain the roughness and related parameters for better understanding. These observations demonstrate the importance of surface statistics in controlling the morphology of the coatings and its properties. From the X-ray diffraction investigations, it can be concluded that the formed nanocomposite coatings are crystalline in nature and that the crystallinity of the coatings decreases with increasing applied current density.展开更多
Self-ordering of the cell arrangement of the anodic porous alumina was prepared in oxalic acid solution at a constant potential of 40V and at a temperature of 20C. The honeycomb structure made by one step anodization...Self-ordering of the cell arrangement of the anodic porous alumina was prepared in oxalic acid solution at a constant potential of 40V and at a temperature of 20C. The honeycomb structure made by one step anodization method and two step anodization method is different. Pores in the alumina film prepared by two step anodization method were more ordered than those by one step anodization method.展开更多
Colorful thin oxide films were synthesized by galvanostatic anodization on Ti−6Al−4V alloy.Three different aqueous solutions containing corrosion inorganic inhibitors(Na_(2)MoO_(4),NaH_(2)PO_(4) and NH4VO3)were employ...Colorful thin oxide films were synthesized by galvanostatic anodization on Ti−6Al−4V alloy.Three different aqueous solutions containing corrosion inorganic inhibitors(Na_(2)MoO_(4),NaH_(2)PO_(4) and NH4VO3)were employed for the anodization treatment.The effect of inhibitor anions on the corrosion behavior of the alloy in Ringer solution was studied.Open circuit potential(OCP),Tafel polarization,linear sweep voltammetry(LSV)and chronoamperometry(CA)were performed to evaluate the corrosion performance of the treated electrodes.The incorporation of the inhibitor ions was detected by the release of Mo,V and P through ICP-AES technique.The formed oxides were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The results show that compact,amorphous oxides without pores or cracks were obtained independently of the solution used.The sample anodized in Na_(2)MoO_(4) solution registered the lowest corrosion current density(0.11μA/cm^(2)),and it was able to protect the alloy even after 168 h of immersion in Ringer solution.No cracks or corrosion products were detected.The XPS analysis reveals the incorporation of molybdenum to the oxide film in the form of Mo^(6+) and Mo^(4+).展开更多
The hot corrosion behavior of Ti45 A18.5 Nb alloy was studied in the salt of Na_(2)SO_(4)and/or NaCl at 700℃.To improve the hot corrosion resistance,Ti45 A18.5 Nb alloy was anodized in fluorine-containing solution an...The hot corrosion behavior of Ti45 A18.5 Nb alloy was studied in the salt of Na_(2)SO_(4)and/or NaCl at 700℃.To improve the hot corrosion resistance,Ti45 A18.5 Nb alloy was anodized in fluorine-containing solution and pre-oxidized in air.Results showed that the combination of anodization and pre-oxidation can efficiently enhance the hot corrosion resistance of Ti45 A18.5 Nb alloy contaminated with Na_(2)SO_(4)or Na_(2)SO_(4)+NaCl deposits.This is because anodization and pre-oxidation result in the formation of compact AlOlayer which can act as a diffusion barrier to prevent sulfur,chlorine,and oxygen from attacking the alloy,therefore providing good resistance against hot corrosion.When exposed to NaCl deposit,however,no obvious improvement was achieved on the hot corrosion behavior no matter the alloy was anodized or further pre-oxidized in air.展开更多
Anodization is a popular method of preparing TiO2nanotube array films（TiNTs） by using direct current（DC）power as the driving voltage.In this study,three driving voltage modes,namely,the sine alternating current（s...Anodization is a popular method of preparing TiO2nanotube array films（TiNTs） by using direct current（DC）power as the driving voltage.In this study,three driving voltage modes,namely,the sine alternating current（sine） mode,the full-wave rectification of sine waves via four diodes（sine-4D,where D means diode） mode,and the DC mode,were used to prepare TiNTs by anodization.At 20 V,TiNTs were formed under sine-4D mode but only irregular porous TiO2films were formed under DC mode.At 50 V,TiNTs formed under both the sine-4D and DC modes.No TiNTs formed in the sine mode anodization at either 20 or 50 V.Compared with the DC mode,the sine-4D mode required a lower oxidation voltage for TiNT formation,which suggests that sine-4D is an economical,convenient,and efficient driving voltage for TiNT preparation by anodization.The morphologies and structures of TiNT samples anodized at 50 V in the sine-4D and DC modes at different oxidation time（1,5,10,30,60,and 120 min） were analyzed.TiNT growth processes were similar between the studied modes.However,the growth rate of the films was faster under the sine-4D mode than the DC mode during the first 30 min of anodization.展开更多
This work presents the potentiostatic anodization study of titania nanotube array films fabricated in fluoride-based organic electrolytes including DEG(diethylene glycol)and EG(ethylene glycol).The work focuses on the...This work presents the potentiostatic anodization study of titania nanotube array films fabricated in fluoride-based organic electrolytes including DEG(diethylene glycol)and EG(ethylene glycol).The work focuses on the effect of important anodization parameters such as applied voltage,anodization time,and electrolyte type on nanotube morphologies and corresponding surface properties.Depending upon unique nanotube formation structures obtained from each anodizing electrolyte,wettability of the nanotube array layer has been determined by means of the contact angle measurement.The EG nanotube array films with close-packing cell orientation are found to show hydrophilic behavior.While the well separated DEG nanotube array films are found to exhibit hydrophobic behavior,with the characteristics of more discrete,wider cell separation obtained through manipulating the electrolyte conditions and the fabrication techniques offering considerable prospects for developing the superhydrophobic sample surface.Such formation structures observed for the DEG fabricated nanotube is believed to play a prominent role in determining the surface wettability of the anodized nanotube array film.The achieved result in this work is anticipated to pave the way to other relevant applications,where interfacial properties are critically concerned.展开更多
Photoactive WO3is attractive as a photocatalyst for green energy evolution through water splitting.In the present work,an electrochemical anodic oxidation method was used to fabricate a photo‐responsive nanotube arra...Photoactive WO3is attractive as a photocatalyst for green energy evolution through water splitting.In the present work,an electrochemical anodic oxidation method was used to fabricate a photo‐responsive nanotube array‐like WO3/W(NA‐WO3/W)photoanode from W foil as a precursor.Compared with a reference commercial WO3/W electrode,the NA‐WO3/W photoanode exhibited enhanced and stable photoelectrocatalytic(PEC)activity for visible‐light‐driven water splitting with a typical H2/O2stoichiometric ratio of2:1and quantum efficiency of approximately5.23%under visible‐light irradiation from a light‐emitting diode(λ=420nm,15mW/cm2).The greatly enhanced PEC performance of the NA‐WO3/Wphotoanode was attributed to its fast electron–hole separation rate,which resulted from the one‐dimensional nanotube array‐like structure,high crystallinity of monoclinic WO3,and strong interaction between WO3and W foil.This work paves the way to a facile route to prepare highly active photoelectrodes for solar light transfer to chemical energy.展开更多
Iron oxide nanostructures are promising materials to be used as photocatalysts in different photoelectrochemical applications. There are different techniques in order to synthesize these nanostructures, but one of the...Iron oxide nanostructures are promising materials to be used as photocatalysts in different photoelectrochemical applications. There are different techniques in order to synthesize these nanostructures, but one of the most inexpensive and simple method is electrochemical anodization. This method can lead to different nanostructures by controlling its parameters. Anodization time is one of the most critical parameters since it considerably affects the properties of the obtained nanostructures. In this work, different anodization times(5, 10, 15, 30 and 60 min) were studied. The resulting nanotubes were characterized by field emission scanning electron microscopy, Raman laser confocal microscopy, water splitting measurements, Mott-Schottky analysis and electrochemical impedance spectroscopy, in order to test their viability for being used as photocatalysts in photoelectrochemical applications. Results showed that the best photocurrent density values in water splitting tests(0.263 m A m-2) were achieved for the sample anodized for 10 min under hydrodynamic conditions.展开更多
Multilayer Nb2O5 nanoporous films were successfully synthesized on Nb surfaces by the control anodization process in ethylene glycol containing 4 vol% HF and 2 vol% H2O2 electrolyte. The nanoporous films are character...Multilayer Nb2O5 nanoporous films were successfully synthesized on Nb surfaces by the control anodization process in ethylene glycol containing 4 vol% HF and 2 vol% H2O2 electrolyte. The nanoporous films are characterized in detail by field-emission scanning electron microscopy（FESEM）, transmission electron microscopy（TEM）, and X-ray diffraction（XRD）. The Nb_2O_5 nanoporous films have a multilayer morphology with the side wall thickness of ～5 nm, irregular pores with a diameter of ～25 nm, and a length of up to 7.39 lm, depending on the anodization time. A mechanism for the multilayer Nb2O5 nanoporous formation was also discussed. These nanoporous materials can be very useful in the fields of solar cells, gas sensors, catalysts, optical filters, and capacitors.展开更多
Highly ordered TiO2 nanotube arrays were fabricated via electrochemical anodization of high purity Ti foil in fluoride-containing electrolyte. The effects of applied anodization potential, anodization time on the form...Highly ordered TiO2 nanotube arrays were fabricated via electrochemical anodization of high purity Ti foil in fluoride-containing electrolyte. The effects of applied anodization potential, anodization time on the formation of TiO2 nanotube arrays and the photocatalytic degradation of methylene blue （MB） were discussed. The TiO2 nanotube arrays calcined at 500 ℃ for 2 h show pure anatase phase. The pore diameters of TiO2 nanotube arrays can be adjusted from 30 to 90 nm using a different anodization voltage. Anodization time mainly influenced TiO2 tube length, and by increasing the anodization time, the nanotube length became longer gradually. When the anodization potential was 40 V, the average growth rate of TiO2 nanotube was about 4.17 μm/h. Both anodization potential and time had important effects on the photocatalytic efficiency. The TiO2 nanotube arrays obtained at anodization potential of 40 V for I h showed the best photocatalytic degradation ratio of MB.展开更多
Electrochemical anodization(EA)is a simple and cost-effective technique to fabricate controlled nanostructures on Ti substrates,such as TiO_(2)nanotubes and nanopores.Electrolyte aging of organic EA electrolytes(repea...Electrochemical anodization(EA)is a simple and cost-effective technique to fabricate controlled nanostructures on Ti substrates,such as TiO_(2)nanotubes and nanopores.Electrolyte aging of organic EA electrolytes(repeated EA using non-target Ti before EA of target Ti)is recognized to influence the characteristics of the anodized nanostructures.However,there is limited information about how surface topography and electrolyte aging dictate the formation and characteristics of the anodized nanostructures.In the current study,short-time EA(starting at 10 s)of micro-machined Ti substrates was performed with electrolytes of various ages(fresh/unused,15 h aged and 30 h aged),followed by evaluation of the TiO_(2)nanopores(TNPs)characteristics in terms of topography,chemistry,stability and protein adhesion.The results showed that aligned TNPs were obtained earlier(120 s)with fresh electrolyte as compared to the aged electrolyte EA(600 s).Interestingly,TNPs fabricated using fresh electrolyte(at lower EA times)showed favorable wettability,protein adhesion capacity and mechanical properties compared with aged electrolyte counterparts.The findings of the study demonstrate how nanopore formation differs between fresh and aged electrolytes when performing EA of micro-machined Ti,which provides an improved understanding of electrolyte aging and its influence on anodized nanostructures.展开更多
One-step pretreatment,anodization,is used to activate the polyacrylonitrile （PAN）-based carbon fibers instead of the routine two-step pretreatment,sensitization with SnCl2 and activation with PdCl2.The effect of the...One-step pretreatment,anodization,is used to activate the polyacrylonitrile （PAN）-based carbon fibers instead of the routine two-step pretreatment,sensitization with SnCl2 and activation with PdCl2.The effect of the anodization pretreatment on the graphitization of PAN-based carbon fibers is investigated as a function of Ni-P catalyst.The PAN-based carbon fibers are anodized in H3PO4 electrolyte resulting in the formation of active sites,which thereby facilitates the following electroless Ni-P coating.Carbon fibers in the presence and absence of Ni-P coatings are heat treated and the structural changes are characterized by X-ray diffraction and Raman spectroscopy,both of which indicate that the graphitization of PAN-based carbon fibers are accelerated by both the anodization treatment and the catalysts Ni-P.Using the anodized carbon fibers,the routine two-step pretreatment,sensitization and activation,is not needed.展开更多
Highly ordered TiO_2 nanotube arrays(NTAs) on Si substrate possess broad applications due to its high surfaceto-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Her...Highly ordered TiO_2 nanotube arrays(NTAs) on Si substrate possess broad applications due to its high surfaceto-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Here, we report a simple and cost-effective high-field(90–180V) anodization method to grow highly ordered TiO_2 NTAs on Si substrate,and investigate the effect of anodization time, voltage, and fluoride content on the formation of TiO_2 NTAs. The current density–time curves, recorded during anodization processes, can be used to determine the optimum anodization time. It is found that the growth rate of TiO_2 NTAs is improved significantly under high field, which is nearly 8 times faster than that under low fields(40–60 V). The length and growth rate of the nanotubes are further increased with the increase of fluoride content in the electrolyte.展开更多
基金financial support from the Science and Technology Development Fund of Egypt (No.5540)。
文摘Integrating titanium-based implants with the surrounding bone tissue remains challenging.This study aims to explore the impact of different anodization voltages(20−80 V)on the surface topography of two-phase(α/β)Ti alloys and to produce TiO_(2) films with enhanced bone formation abilities.Scanning electron microscopy coupled with energy dispersive spectroscopy(SEM−EDS)and atomic force microscopy(AFM)were applied to investigate the morphological,chemical,and surface topography of the prepared alloys and to confirm the growth of hydroxyapatite(HA)on their surfaces.Results disclosed that the surface roughness of TiO_(2) films formed on Ti−6Al−7Nb alloys was superior to that of Ti−6Al−4V alloys.Ti−6Al−7Nb alloy anodized at 80 V had the highest yields of HA after immersion in simulated body fluid with enhanced HA surface coverage.The developed HA layer had a mean thickness of(128.38±18.13)μm,suggesting its potential use as an orthopedic implantable material due to its promising bone integration and,hence,remarkable stability inside the human body.
基金Project(1254G024)supported by the Young Core Instructor Foundation from Heilongjiang Educational Committee,ChinaProject(2012RFQXS113)supported by Scientific and Technological Innovation Talents of Harbin,China
文摘Both Ti foil and porous Ti were anodized in 0.5%HF and in ethylene glycol electrolyte containing 0.5%NH4F(mass fraction) separately. The results show that TiO2 nanotubes can be formed on Ti foil by both processes, whereas TiO2 nanotubes can be formed on porous Ti only in the second process. The overhigh current density led to the failure of the formation nanotubes on porous Ti in 0.5%HF electrolyte. TiO2 nanotubes were characterized by SEM and XRD. TiO2 nanotubes on porous Ti were thinner than those on Ti foil. Anatase was formed when TiO2 nanotubes were annealed at 400 °C and fully turned into rutile at 700 °C. To obtain good photodegradation, the optimal heat treatment temperature of TiO2 nanotubes was 450 °C. The porosity of the substrates influenced photodegradation properties. TiO2 nanotubes on porous Ti with 60% porosity had the best photodegradation.
基金Project(S2012010010417)supported by the Guangdong Natural Science Foundation,ChinaProject(20130172110008)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘A facile route for preparation of gradient wettability surface on copper substrate with contact angle changing from 90.3°to4.2°was developed.The Cu（OH）2 nanoribbon arrays were electrochemically deposited on copper foil via a modified anodization technology,and the growth degree and density of the Cu（OH）2 arrays may be controlled varying with position along the substrate by slowly adding aqueous solution of KOH into the two-electrode cell of an anodization system to form the gradient surface.The prepared surface was water resistant and thermal stable,which could keep its gradient wetting property after being immersed in water bath at 100℃ for 10 h.The results of scanning electron microscopy（SEM）,X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS） demonstrate that the distribution of Cu（OH）2 nanoribbon arrays on copper surface are responsible for the gradient wettability.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(51971205)Shenzhen Science and Technology Innovation Program,China(JCYJ20190807154005593)the Fundamental Research Funds for the Central Universities,China(19lgpy20).
文摘To shield TiAl alloy from hot corrosion attack,a compact protective coating was fabricated by the combination of aluminizing,anodization and pre-oxidation.The hot corrosion behavior of the coated-TiAl specimen was investigated in the mixture salt consisting of 75 wt.%Na2SO4 and 25 wt.%NaCl at 700°C.Results indicated that the anodization and pre-oxidation were beneficial to the generation of Al2O3 layer,which could act as a diffusion barrier to prevent the molten salts and oxygen from diffusing into the alloy during exposure to a hot corrosion environment while the aluminizing coating could provide sufficient aluminum source to support the continuous formation of Al2O3 layer.Moreover,the internal stress of the coating was reduced due to the formation of a gradient coating consisting of TiAl3 and TiAl2.
基金the National Natural Science Foundation of China(No.61376017)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSFDH-D-2020094)the Shanghai Sailing Program(No.17YF1400600)。
文摘Self-organized titanium dioxide(TiO_(2))nanotubes,which are prepared by electrochemical anodizing,have been widely researched as promising anodes for Liion batteries.Both nanotubular morphology and bulk structure of TiO_(2)nanotubes can be easily changed by adjusting the anodizing and annealing parameters.This is provided to investigate different phenomena by selectively adjusting a specific parameter of the Li^(+)insertion mechanism.In this paper,we reviewed how the morphology and crystallography of TiO_(2)nano tubes influence the electrochemical performance of Li^(+)batteries.In particular,electrochemical performances of amorphous and anatase titanium dioxide nanotube anodes were compared in detail.As we all know,TiO_(2)nanotube anodes have the advantages of nontoxicity,good stability,high safety and large specific surface area,in lithium-ion batteries.However,they suffer from poor electronic conductivity,inferior ion diffusivity and low theoretical capacity(335 mAh·g^(-1)),which limit their practical application.Generally,there are two ways to overcome the shortcomings of titanium dioxide nanotube anodes,including doping and synthesis composites.The achievements and existing problems associated with doped TiO_(2)nanotube anodes and composite material anodes are summarized in the present review.Based on the analysis of lithium insertion mechanism of titanium dioxide nanotube electrodes,the prospects and possible research directions of TiO_(2)anodes in lithiumion batteries are discussed.
基金This study was financially supported by the Fund for Shanxi"1331 Project"Key Innovative Research Team(No.PY201809)the Natural Science Foundation of Shanxi Province(No.201801D121093)Hong Kong Research Grants Council General Research Funds(No.CityU 11205617).
文摘Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer,but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer and antibacterial properties to inhibit cancer/bacteria invasion.The present work aims at endowing the NiTi alloy with anticancer and antibacterial abilities by surface modification.Ni–Ti–O nanoporous layers with different thicknesses were prepared on NiTi by anodization,and biological experiments were conducted to evaluate the effects on gram-positive Staphylococcus aureus,human lung epithelial cancer cells(A549),as well as human endothelial cells(EA.hy926).The nanoporous layer with a thickness of 10.1 lm inhibits growth of cancer cells and kill bacteria but shows little adverse effects on normal cells.Such selectivity is related to the larger amount of Ni ions leached from the sample in the acidic microenvironment of cancer cells in comparison with normal cells.The Ni–Ti–O nanoporous layers are promising as coatings on NiTi stents to prevent re-obstruction after surgery.
基金supported by the National Natural Science Foundation of China (Grant No. 51102246)the Knowledge Innovation Program of Institute of Metal Research, Chinese Academy of Sciences (Grant No.Y0N5A111A1)the Youth Innovation Promotion Association, Chinese Academy of Sciences (Grant No.Y2N5711171)
文摘Well crystallized niobium-doped TiO; nanotube arrays （TiNbO-NT） were successfully synthesized via the anodization of titanium/niobium alloy sheets, followed with a heat treatment at 550 ℃ for 2 h. Morphology analysis results demonstrated that both the titanium/niobium alloy microstructure and the dissolution strength of electrolyte played major roles in the formation of nanotube structure. A single-phase microstructure was more favorable to the formation of uniform nanotube arrays, while modulating the dissolution strength of electrolyte was required to obtain nanotube arrays from the alloys with multi-phase microstructures. X-ray diffraction （XRD） and X-ray photoelectron （XPS） analysis results clearly demonstrated that niobium dopants （Nb^5＋） were successfully doped into TiO2 anatase lattice by substituting Ti^4＋ in this approach.
基金the Council of Scientific and Industrial Research, New Delhi for awarding CSIR-SRF(senior research fellow ship- 09/810(0011) 2010 EMR)
文摘Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization. The effects of current density （CD） on microhardness, structure, composition and surface topography of the oxide layer formed at various CDs （0.1-0.25 A/cm^2） have been studied. Crystalline coatings formed at 0.25 A/cm^2 have been （width 95 nm） observed with a relatively uniform distribution confirmed by scanning electron microscopy. Additionally, the average microhardness value of ceramic nanocomposite coatings fabricated from lithium sulphate-zirconium silicate bath is approximately 8.5 times higher than that of the as-received aluminium. The surface statistics of the coatings is discussed in detail to explain the roughness and related parameters for better understanding. These observations demonstrate the importance of surface statistics in controlling the morphology of the coatings and its properties. From the X-ray diffraction investigations, it can be concluded that the formed nanocomposite coatings are crystalline in nature and that the crystallinity of the coatings decreases with increasing applied current density.
文摘Self-ordering of the cell arrangement of the anodic porous alumina was prepared in oxalic acid solution at a constant potential of 40V and at a temperature of 20C. The honeycomb structure made by one step anodization method and two step anodization method is different. Pores in the alumina film prepared by two step anodization method were more ordered than those by one step anodization method.
基金The financial supports of the Secretaría de Ciencia y Técnica-UNS (PGI 24/M159)the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-PIP 112-20150-100147)the Agencia Nacional de Promoción Científica y Tecnológica (ANPCy T-PICT 2015-0726)。
文摘Colorful thin oxide films were synthesized by galvanostatic anodization on Ti−6Al−4V alloy.Three different aqueous solutions containing corrosion inorganic inhibitors(Na_(2)MoO_(4),NaH_(2)PO_(4) and NH4VO3)were employed for the anodization treatment.The effect of inhibitor anions on the corrosion behavior of the alloy in Ringer solution was studied.Open circuit potential(OCP),Tafel polarization,linear sweep voltammetry(LSV)and chronoamperometry(CA)were performed to evaluate the corrosion performance of the treated electrodes.The incorporation of the inhibitor ions was detected by the release of Mo,V and P through ICP-AES technique.The formed oxides were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The results show that compact,amorphous oxides without pores or cracks were obtained independently of the solution used.The sample anodized in Na_(2)MoO_(4) solution registered the lowest corrosion current density(0.11μA/cm^(2)),and it was able to protect the alloy even after 168 h of immersion in Ringer solution.No cracks or corrosion products were detected.The XPS analysis reveals the incorporation of molybdenum to the oxide film in the form of Mo^(6+) and Mo^(4+).
基金supported by the National Natural Science Foundation of China(No.51971205)the Guangdong Basic and Applied Basic Research Foundation(No.2021B1515020056)the Basic Research Project of Shenzhen Science and Technology Innovation Program(No.JCYJ20190807154005593)。
文摘The hot corrosion behavior of Ti45 A18.5 Nb alloy was studied in the salt of Na_(2)SO_(4)and/or NaCl at 700℃.To improve the hot corrosion resistance,Ti45 A18.5 Nb alloy was anodized in fluorine-containing solution and pre-oxidized in air.Results showed that the combination of anodization and pre-oxidation can efficiently enhance the hot corrosion resistance of Ti45 A18.5 Nb alloy contaminated with Na_(2)SO_(4)or Na_(2)SO_(4)+NaCl deposits.This is because anodization and pre-oxidation result in the formation of compact AlOlayer which can act as a diffusion barrier to prevent sulfur,chlorine,and oxygen from attacking the alloy,therefore providing good resistance against hot corrosion.When exposed to NaCl deposit,however,no obvious improvement was achieved on the hot corrosion behavior no matter the alloy was anodized or further pre-oxidized in air.
基金the financial support provided by the National Natural Science Foundation of China (Nos. 21277004, 21190051 and 41121004)the Beijing Natural Science Foundation, China (No. 8132035)
文摘Anodization is a popular method of preparing TiO2nanotube array films（TiNTs） by using direct current（DC）power as the driving voltage.In this study,three driving voltage modes,namely,the sine alternating current（sine） mode,the full-wave rectification of sine waves via four diodes（sine-4D,where D means diode） mode,and the DC mode,were used to prepare TiNTs by anodization.At 20 V,TiNTs were formed under sine-4D mode but only irregular porous TiO2films were formed under DC mode.At 50 V,TiNTs formed under both the sine-4D and DC modes.No TiNTs formed in the sine mode anodization at either 20 or 50 V.Compared with the DC mode,the sine-4D mode required a lower oxidation voltage for TiNT formation,which suggests that sine-4D is an economical,convenient,and efficient driving voltage for TiNT preparation by anodization.The morphologies and structures of TiNT samples anodized at 50 V in the sine-4D and DC modes at different oxidation time（1,5,10,30,60,and 120 min） were analyzed.TiNT growth processes were similar between the studied modes.However,the growth rate of the films was faster under the sine-4D mode than the DC mode during the first 30 min of anodization.
文摘This work presents the potentiostatic anodization study of titania nanotube array films fabricated in fluoride-based organic electrolytes including DEG(diethylene glycol)and EG(ethylene glycol).The work focuses on the effect of important anodization parameters such as applied voltage,anodization time,and electrolyte type on nanotube morphologies and corresponding surface properties.Depending upon unique nanotube formation structures obtained from each anodizing electrolyte,wettability of the nanotube array layer has been determined by means of the contact angle measurement.The EG nanotube array films with close-packing cell orientation are found to show hydrophilic behavior.While the well separated DEG nanotube array films are found to exhibit hydrophobic behavior,with the characteristics of more discrete,wider cell separation obtained through manipulating the electrolyte conditions and the fabrication techniques offering considerable prospects for developing the superhydrophobic sample surface.Such formation structures observed for the DEG fabricated nanotube is believed to play a prominent role in determining the surface wettability of the anodized nanotube array film.The achieved result in this work is anticipated to pave the way to other relevant applications,where interfacial properties are critically concerned.
基金supported by the National Natural Science Foundation of China(21207090,21477079,21261140333)PCSIRT(IRT1269)a scheme administrated by Shanghai Normal University(DXL122,and S30406)~~
文摘Photoactive WO3is attractive as a photocatalyst for green energy evolution through water splitting.In the present work,an electrochemical anodic oxidation method was used to fabricate a photo‐responsive nanotube array‐like WO3/W(NA‐WO3/W)photoanode from W foil as a precursor.Compared with a reference commercial WO3/W electrode,the NA‐WO3/W photoanode exhibited enhanced and stable photoelectrocatalytic(PEC)activity for visible‐light‐driven water splitting with a typical H2/O2stoichiometric ratio of2:1and quantum efficiency of approximately5.23%under visible‐light irradiation from a light‐emitting diode(λ=420nm,15mW/cm2).The greatly enhanced PEC performance of the NA‐WO3/Wphotoanode was attributed to its fast electron–hole separation rate,which resulted from the one‐dimensional nanotube array‐like structure,high crystallinity of monoclinic WO3,and strong interaction between WO3and W foil.This work paves the way to a facile route to prepare highly active photoelectrodes for solar light transfer to chemical energy.
基金financial support granted to Bianca Lucas Granados by the Ministerio de Economía y Competitividad(Reference,BES-2014-068713 and Project CTQ2016-79203-R)for its help in the Laser Raman Microscope acquisition(UPOV08-3E-012)+1 种基金the co-finance by the European Social Fundthe UPV for the concession of a postdoctoral grant(PAID-10-17)to Ramón M.Fernández Domene.
文摘Iron oxide nanostructures are promising materials to be used as photocatalysts in different photoelectrochemical applications. There are different techniques in order to synthesize these nanostructures, but one of the most inexpensive and simple method is electrochemical anodization. This method can lead to different nanostructures by controlling its parameters. Anodization time is one of the most critical parameters since it considerably affects the properties of the obtained nanostructures. In this work, different anodization times(5, 10, 15, 30 and 60 min) were studied. The resulting nanotubes were characterized by field emission scanning electron microscopy, Raman laser confocal microscopy, water splitting measurements, Mott-Schottky analysis and electrochemical impedance spectroscopy, in order to test their viability for being used as photocatalysts in photoelectrochemical applications. Results showed that the best photocurrent density values in water splitting tests(0.263 m A m-2) were achieved for the sample anodized for 10 min under hydrodynamic conditions.
基金financially supported by the National Natural Science Foundation of China (Nos. 50902115 and 51104121)
文摘Multilayer Nb2O5 nanoporous films were successfully synthesized on Nb surfaces by the control anodization process in ethylene glycol containing 4 vol% HF and 2 vol% H2O2 electrolyte. The nanoporous films are characterized in detail by field-emission scanning electron microscopy（FESEM）, transmission electron microscopy（TEM）, and X-ray diffraction（XRD）. The Nb_2O_5 nanoporous films have a multilayer morphology with the side wall thickness of ～5 nm, irregular pores with a diameter of ～25 nm, and a length of up to 7.39 lm, depending on the anodization time. A mechanism for the multilayer Nb2O5 nanoporous formation was also discussed. These nanoporous materials can be very useful in the fields of solar cells, gas sensors, catalysts, optical filters, and capacitors.
基金partly supported by the National Natural Science Foundation of China (Grant No. 61405171)the Shandong Province Natural Science Foundation (No. ZR2012FQ014)the Shandong Province Higher Educational Science and Technology Program (No. G12LA08, No. J13LJ05)
文摘Highly ordered TiO2 nanotube arrays were fabricated via electrochemical anodization of high purity Ti foil in fluoride-containing electrolyte. The effects of applied anodization potential, anodization time on the formation of TiO2 nanotube arrays and the photocatalytic degradation of methylene blue （MB） were discussed. The TiO2 nanotube arrays calcined at 500 ℃ for 2 h show pure anatase phase. The pore diameters of TiO2 nanotube arrays can be adjusted from 30 to 90 nm using a different anodization voltage. Anodization time mainly influenced TiO2 tube length, and by increasing the anodization time, the nanotube length became longer gradually. When the anodization potential was 40 V, the average growth rate of TiO2 nanotube was about 4.17 μm/h. Both anodization potential and time had important effects on the photocatalytic efficiency. The TiO2 nanotube arrays obtained at anodization potential of 40 V for I h showed the best photocatalytic degradation ratio of MB.
基金supported by the UQ Graduate School Scholarships(UQGSS),funded by the University of Queenslandsupported by the National Health and Medical Research Council(NHMRC)Early Career Fellowship(APP1140699)supported by a grant from the ITI Foundation,Switzerland。
文摘Electrochemical anodization(EA)is a simple and cost-effective technique to fabricate controlled nanostructures on Ti substrates,such as TiO_(2)nanotubes and nanopores.Electrolyte aging of organic EA electrolytes(repeated EA using non-target Ti before EA of target Ti)is recognized to influence the characteristics of the anodized nanostructures.However,there is limited information about how surface topography and electrolyte aging dictate the formation and characteristics of the anodized nanostructures.In the current study,short-time EA(starting at 10 s)of micro-machined Ti substrates was performed with electrolytes of various ages(fresh/unused,15 h aged and 30 h aged),followed by evaluation of the TiO_(2)nanopores(TNPs)characteristics in terms of topography,chemistry,stability and protein adhesion.The results showed that aligned TNPs were obtained earlier(120 s)with fresh electrolyte as compared to the aged electrolyte EA(600 s).Interestingly,TNPs fabricated using fresh electrolyte(at lower EA times)showed favorable wettability,protein adhesion capacity and mechanical properties compared with aged electrolyte counterparts.The findings of the study demonstrate how nanopore formation differs between fresh and aged electrolytes when performing EA of micro-machined Ti,which provides an improved understanding of electrolyte aging and its influence on anodized nanostructures.
基金Funded by the National Basic Research Program of China (No.2006CB600903)
文摘One-step pretreatment,anodization,is used to activate the polyacrylonitrile （PAN）-based carbon fibers instead of the routine two-step pretreatment,sensitization with SnCl2 and activation with PdCl2.The effect of the anodization pretreatment on the graphitization of PAN-based carbon fibers is investigated as a function of Ni-P catalyst.The PAN-based carbon fibers are anodized in H3PO4 electrolyte resulting in the formation of active sites,which thereby facilitates the following electroless Ni-P coating.Carbon fibers in the presence and absence of Ni-P coatings are heat treated and the structural changes are characterized by X-ray diffraction and Raman spectroscopy,both of which indicate that the graphitization of PAN-based carbon fibers are accelerated by both the anodization treatment and the catalysts Ni-P.Using the anodized carbon fibers,the routine two-step pretreatment,sensitization and activation,is not needed.
基金supported by National 863 Program 2011AA050518the Natural Science Foundation of China(Grant Nos.11174197,11574203,and 61234005)
文摘Highly ordered TiO_2 nanotube arrays(NTAs) on Si substrate possess broad applications due to its high surfaceto-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Here, we report a simple and cost-effective high-field(90–180V) anodization method to grow highly ordered TiO_2 NTAs on Si substrate,and investigate the effect of anodization time, voltage, and fluoride content on the formation of TiO_2 NTAs. The current density–time curves, recorded during anodization processes, can be used to determine the optimum anodization time. It is found that the growth rate of TiO_2 NTAs is improved significantly under high field, which is nearly 8 times faster than that under low fields(40–60 V). The length and growth rate of the nanotubes are further increased with the increase of fluoride content in the electrolyte.
