Nanotubular Layers Research Articles

Nanotubular oxide layers formation on Ti–24Nb–4Zr–8Sn and Ti–13Zr–13Nb alloys in the ethylene glycol-based electrolyte: The role of alloying elements and phase composition

In this work, the self-organized mixed-oxide nanotubes (NTs) have been fabricated on a commercially pure α-phase titanium, single β-phase Ti–24Nb–4Zr-8Sn alloy and α+β-phase Ti–13Zr–13Nb alloy. Anodization process was performed in ethylene glycol-based electrolyte with fluoride ions at constant voltage of 20 V for 2 h. Morphology of obtained NTs was characterized by scanning and transmission electron microscopy and the chemical analysis was performed by Auger electron and X-ray photoelectron spectroscopy methods. Despite of applying the same process parameters in all cases, NTs obtained on three different substrates showed a different morphology: ribbed walls for titanium and smooth walls for Ti–24Nb–4Zr–8Sn and Ti–13Zr–13Nb alloys. The presence of alloying additives as well as phase composition of both Ti alloys strongly affected the uniformity and height of the obtained nanotubular layers. NTs layers formed on the surface of both Ti alloys were significantly higher but also more inhomogeneous in comparison to pure Ti. Moreover, NTs of different heights were observed on Ti–13Zr–13Nb, the higher growing on the β phase and lower on the α phase. Anodization of titanium alloys led to obtaining layers with mixture of stoichiometric oxides – TiO2, Nb2O5, ZrO2, SnO2.

Anodic Oxide Growth on Heat-Treated Titanium

It has been reported that self-organized nanotubular oxide layers are formed on various metals and alloys by anodization in fluoride containing electrolytes. In particular, the nanotubular structure of TiO2 has been extensively studied due to a wide range of application of TiO2. To tune the properties of the layers, the optimization of anodization condition has been carried out. However, in such trials, the chemical aspects of anodization condition have been mainly focused, that is, only few works has reported the metallurgical aspects of the condition. In the present work, we examined the effects of heat-treatment on anodization behavior and resulting morphology of the TiO2 architecture. Specimens were cut from pure titanium sheets (purity; 99.5 %). The specimens were encapsulated into a silica quartz tube where the vacuum level was controlled less than approximately 2x10-5 torr. The specimens in the silica tube were heat-treated under several conditions. After the heat-treatments, the surface of the specimens was ground with SiC abrasive papers and then mirror-finished with diamond pates and colloidal silica suspension. The specimens were anodized at 50 V in a mixture of ethylene glycol, water and ammonium fluoride. After the anodization, the surface and cross-sectional morphology of resulting oxide layers was observed. Under an optimized heat-treatment condition examined, the specimen consisting of large grains in millimeter range was obtained. The anodization of the specimen revealed that its current behavior was similar to that obtained on as-received specimen. In addition, the obtained structure of anodic oxide layer on the heat-treated specimen was also similar to that on as-received specimen, that is, nanotubular structure was obtained. However, the thickness of the nanotubular oxide layer and the ordering of nanotubes were clearly different. Higher thickness of nanotubular oxide layer was obtained and improved ordering of nanotubes was found on the heat-treated specimen. These results indicate that the substrate property could affect not only the growth but also arrangement of nanotubes.

Noble Metal Decorated Anodic TiO2 Nanotubes: Excellent (Electro)Catalyst

The synthesis of highly-ordered nanostructures of valve metal oxides has recently attracted huge scientific and technological interest motivated by their possible use in many applications. The most established member of this group of materials is nanoporous Al2O3, which has been prepared two decades ago by anodic oxidation of Al into perfectly ordered, honeycomb-like porous structures employing suitable electrochemical conditions [1]. Owing to the flexibility of the pore diameter/length and the relative ease of the Al2O3 dissolution, its porous membranes have been since than widely used as template material of choice for a range of materials [2-4]. Self-organized TiO2 nanotube layers have received the highest attention after Al2O3 motivated by its range of applications, including photocatalysis, water splitting, solar cells and biomedical uses. Very significant research efforts have led to reproducible synthesis of self-organized TiO2 nanotube layers by means of anodic oxidation, during which the starting Ti substrate is converted into a highly-ordered nanotubular layer by anodization in suitable electrolytes [5-8]. Many new applications can be derived upon modification of the nanotubes by decoration, filling or coating by secondary materials [9]. Atomic layer deposition (ALD) has been shown to be an effective technique to coat TiO2 nanotube layers homogenously with secondary materials or to decorate them with noble metals [9]. The resulting structures offer many advantages and opportunities in various applications. TiO2 nanotubes in particular appeal as highly ordered electron-conductive supports for noble metal particles. This presentation will focus in detail on the decoration of the nanotube layers of different aspect ratios by noble metals using ALD. We will show and discuss our recent catalytic results on water splitting [10] and electrocatalytic results on the oxidation of methanol [11].

The influence of the surface nanostructured modification on the corrosion resistance of the ultrafine-grained Ti–13Nb–13Zr alloy in artificial saliva

On the surface of the ultrafine-grained Ti–13Nb–13Zr alloy and the coarse-grained Ti–13Nb–13Zr alloy nanotubular oxide layers were formed by electrochemical anodization in the 1 M H3PO4 + NaF electrolyte in order to evaluate the electrochemical behaviour in the artificial saliva. SEM images showed that homogeneous nanotubular oxide layers could be formed by anodic oxidation of titanium alloys in an electrolyte with fluoride ions. These two titanium alloys, like other materials developed to replace the bone tissue in the human body, have to be highly corrosion resistant, which is one of the most common requirement in terms of the biocompatibility, damage and fracture prevention. The alloys were analysed by means of the electrochemical impedance spectroscopy and potentiodynamic polarization. The analyzed alloys had good corrosion stability, while nanotubular oxide layer improved their corrosion resistance.

Effects of electrophoretic deposition times and nanotubular oxide surfaces on properties of the nanohydroxyapatite/nanocopper coating on the Ti13Zr13Nb alloy

Load-bearing implants are developed with a particular emphasis placed on an application of ceramic hydroxyapatite coatings in order, to enhance the bioactivity of titanium implants and to shorten the healing time. Therefore, thin, fully crystalline coatings that are, highly adhesive, hydrophilic and demonstrating antibacterial properties are ly looked for. The aim of this research was to develop and characterize the properties of (nano)hydroxyapatite coatings implemented with nanocopper particles and obtained by the electrophoretic method. The deposition was carried out on the Ti13Zr13Nb alloy, either on a bare surface or a nanotubular oxide layer. The deposition was made for 1 or 2 min. The chemical composition, phase composition, coating structure, homogeneity, thickness, nanoindentation and nanomechanical properties, adhesion determined by a nanoscratch test, and wettability measured by a contact angle were investigated. The presence of nanotubular oxide layers caused no significant change in nanoindentation and nanomechanical propertie and an increase in adhesion strength and a decrease in the contact angle. The increase in deposition time resulted in an increased thickness, a decreased hardness, an increased adhesion strength and wettabilty. The observed effects in the composite (nano)HAp/Cu – (nano)TiO2 coatings are attributed to the change in the structure of coatings following the increasing deposition time and coating thickness.

Biocompatibility of Nanoscale Hydroxyapatite Coating on TiO2 Nanotubes.

In this study, a highly-ordered TiO2 nanotube array was successfully fabricated on the surface of a pure titanium foil using the anodization method, and a hydroxyapatite (HA) layer was electrochemically deposited on the vertically aligned titania (TiO2) nanotube array. The TiO2 nanotubes exhibited an inner diameter ranging from 44.5 to 136.8 nm, a wall thickness of 9.8 to 20 nm and a length of 1.25 to 3.94 µm, depending on the applied potential, and the anodization time and temperature. The TiO2 nanotubes provided a high number of nucleation sites for the HA precipitation during electrochemical deposition, resulting in the formation of a nanoscale HA layer with a particle size of about 50 nm. The bond strength between the HA coating and the nanotubular layer with an inner diameter of 136.8 nm was over 28.7 MPa, and the interlocking between the nanoscale HA and the TiO2 nanotubes may have been responsible for the high bond strength. The biocompatibility assessment was conducted on Ti foil with a composite coat of nanoscale HA and the TiO2 nanotube array by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) array with mesenchymal stem cells (MSCs). The mesenchymal stem cells adhered to and spread onto the nanoscale HA layer with plenty of extending filopodia, indicating excellent biocompatibility of the HA coat, the composite coat of nanoscale HA and the TiO2 nanotube array. The findings suggest that the nanoscale HA coating on the TiO2 nanotube array might be a promising way to improve the bond strength and the compatibility of the HA layer.

(Invited) A New Perspective for Photoelectrochemical Water Splitting: Black TiO2 Nanotubes

In the past decade, anodically formed self-organized TiO2 nanotube layers attracted considerable scientific interest (see e.g. reviews [1,2]). This is mainly due to the fact that these layers combine the defined nanotubular geometry with a broad range of functional features inherent to TiO2. Particularly in photoelectrochemical water splitting nanotubular layers have shown remarkable results. The presentation will first give an overview of the most promising features of classic nanotube layers for photocatalysis and then focus on TiO2 nanotube (NT) arrays, converted by a high pressure H2 treatment to anatase-like "black titania"[3,4]. This modification shows a remarkable high open-circuit photocatalytic hydrogen production rate without the presence of any cocatalyst. Other attempts to form black titania, namely using classic reduction treatments (e.g., atmospheric pressure H2/Ar annealing) do not show this surprising effect. We will discuss the main difference caused by the high H2 pressure annealing and the origin of this outstanding activity of black titania. REFERENCES Roy, S. Berger, P. Schmuki, Angew. Chem. Int. Ed. (2011), 2904Lee, A. Mazare, P. Schmuki, CHEMICAL REVIEWS, 114 (2014) 9385Liu, P. Schmuki et.al. Nano Letters, 14 (2014) 3309Liu, P. Schmuki et.al. 53 (2014) 14201

Ti plate with TiO2 nanotube arrays as a novel cathode for nitrate reduction

The purpose of this research is to investigate the possibility of using a Ti plate with TiO2 nanotube arrays as a novel cathode for nitrate reduction. TiO2 nanotube arrays were grown on a Ti plate by anodization in a glycerol based electrolyte and annealed to change their crystallographic structure. Morphological and crystallographic structures of Ti plates with a TiO2 nanotubular layer were analysed before and after anodization or annealing by using energy-dispersive spectroscopy, Brunauer-Emmett-Teller analysis and X-ray diffraction. Cyclic voltammetry and electrochemical impedance spectroscopy were also performed to test the electrochemical reactivity towards nitrate reduction. A lab-scale electrochemical reactor with a RuO2/Ti anode and a Ti plate with a TiO2 nanotubular layer as a cathode was operated to treat synthetic wastewater containing up to 600 mg L−1 of NO3-N. The Ti plate with a TiO2 nanotubular layer was compared with other cathodes such as Ti, Cu, Ni, and Stainless Steel. The Ti plate with an anatase TiO2 nanotubular layer with a layer thicknesses greater than 45 μm was able to show the most efficient nitrate reduction.

Tailoring the morphology of nanotubular oxide layers on Ti-24Nb-4Zr-8Sn β-phase titanium alloy

In the present work, the self-organized mixed-oxide nanotubes (NTs) has been obtained on the Ti2448 β-phase alloy by electrochemical anodization process. NTs of 54–93 nm in diameter with different morphology can be obtained by tailoring the chemical composition of solution and anodization parameters. Well-ordered structures with both ribbed and smooth walls were fabricated. The most homogenous NTs were obtained as a result of anodization in ethylene glycol-based solution with 10% of water. The X-ray photoelectron spectroscopy and Auger electron spectroscopy results indicate that the obtained nanotubular layer mainly consists of the stoichiometric oxides TiO2 and Nb2O5 and a small amount of ZrO2 and SnO which are located throughout entire NTs height. The obtained NTs oxide layers exhibits superhydrophilic properties.

Tailoring electrochemical efficiency of hydrogen evolution by fine tuning of TiOx/RuOx composite cathode architecture

Here we report an approach to design composite cathode based on TiOx nanotubes decorated with RuOx nanowhiskers for efficient hydrogen evolution. We tailor catalytic activity of the cathodes by adjustment of morphology of TiOx nanotubular support layer along with variation of RuOx loaded mass and assess its performance using electrochemical methods and wavelet analysis.The highest energy efficiency of hydrogen evolution is observed in 1 M H2SO4 electrolyte to be ca. 64% at −10 mA/cm2 for cathodes of the most developed area, i.e. smaller diameter of tubes, with enhanced RuOx loading. The efficiency is favored by detachment of small hydrogen bubbles what is revealed by wavelet analysis and is expressed in pure noise at wavelet spectrum. At increased current density, −50 or −100 mA/cm2, better efficiency of composite cathodes is supported by titania nanotubes of larger diameter due to an easier release of large hydrogen bubbles manifested in less periodic events appeared in the frequency region of 5–12 s at the spectra.We have shown that efficiency of the catalysts is determined by a pre-dominant type of hydrogen bubble release at different operation regimes depending on specific surface and a loaded mass of ruthenia.

Effect of fluoride-mediated transformations on electrocatalytic performance of thermally treated TiO2 nanotubular layers

Abstract The peculiarities of morphology, crystalline structure and chemical composition of TiO 2 nanotubular layers (TNT) and TiO 2 nanoparticulate (NP) layers obtained by fluoride-mediated transformation of TNT have been described in the present paper. The annealing of amorphous TNT in a confined space under limited air access conditions leads to TNT-to-NP transformation accompanied by fluorine doping of the titania matrix as supported by X-ray photoelectron spectroscopy investigations. The collapse of tubular structure as well as the formation of nanoparticles was confirmed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Electrocatalytic activity of both TNT and NP electrodes toward oxygen reduction reaction (ORR) has been examined by cyclic voltammetry (CV). The positive shift of ORR wave of the NP layers in comparison with TNT makes the NP-based electrodes more suitable for oxygen reduction. The improved activity of the NP electrodes is attributed to the increased concentration of redox active Ti 3+ species owing to fluorine doping of TiO 2 which plays a crucial role in electroreduction of oxygen molecules.

Electrosynthesis of Ordered TiO2 Nanotubular Layers in Deep Eutectic Solvents and Their Properties

The successful preparation of the titania nanotubular layers (TNT) in different deep eutectic solvent based electrolytes was performed in the current work. Choline chloride based deep eutectic solvents with various hydrogen bond donors, such as ethylene glycol, urea and malonic acid were used. All results were compared with standard ethylene glycol based electrolyte. The influence of the solution temperature, fluoride ion concentration, applied voltage and anodization time on morphology of the titania nanotubular layers was explored. It was demonstrated for the first time that the use of very viscous electrolytes request use of higher temperature. General trends for deep eutectic solvent based electrolytes and optimum anodization parameters for each system were developed. It was found that the morphology of the films prepared in choline chloride with urea and malonic acid systems is closer to TNT prepared in water solution than in TNT obtained from organic based electrolytes. Influence of the viscous electrolytes on pores formation rate was demonstrated. The texture of the annealed films was investigated by XRD and shows strong differences in properties depending on hydrogen bond donors. Moreover, physicochemical properties were measured, including photocurrent and apparent donor concentration.

Growth of a TiO2 nanotubular layer without presence of nanograss in a short time

Many studies, focused in TiO2 anodized, uses frequently a NH4F salt concentration from 0.3 – 0.5 wt% and the whole information about how voltage, time and even pH affects to nanotubes morphology, are effective just for these concentration range. It is known, increasing salt concentration, the electrolyte increases their conductivity and anodization speed (oxidation-dissolution) suffer also an increment and for a specifically concentration 1.2wt%, there is no data about morphology repercussions. A TiO2 nanotubular matrix is synthesized, in order to identify the range of time where it is possible to obtain with no presence of nanograss. The anodization process consists of an organic electrolyte of ethylene glycol, deionized water and 1.2 wt% NH4F salts, constant potential of 30 V and a time lapse from 10 to 60 minutes (short time). All anodized samples are rinsed and annealed to 400 °C by 4 hours to obtain an anatase crystalline structure; no samples are cleaned in ultrasonic bath to preserve the nanograss structure. Optical characterization was performed by Raman Spectroscopy to identify the increases in signal intensity, associated with thickness. The morphological characterization was carried out by Scanning Electron Microscopy to verify the presence and density of the nanograss and nanotubes.

Nanotubular oxide layers formed on the Ti-based implants surfaces-application and possible damages: a review

Implant surface properties define the interaction of the implant with the surrounding tissue. To obtained advanced biological, mechanical and physical properties, metallic implants are often exposed to different kinds of surface modification. The electrochemical anodization process is an efficient method for nanostructured surface modification, which leads to the formation of nanotubular oxide layers on metallic surfaces. These obtained layers could be applied in biomedicine due to their chemical stability, biocompatibility and non-toxic nature in the human body. As a part of different kinds of medical implants such as dental implants, artificial hip joints, bone plates, screws, spinal fixation devices or stents, an oxide layer significantly increases cells adhesion and plays a significant role in improving the rate of osseointegration. However, an important topic in research of implants with a nanotubular oxide layer is integrity during fixation and exploitation and possible damage initiation and development. This review article aims to present the application of nanotubular oxide layers in biomedicine and to explain their influence on the biocompatibility and osseointegration of medical implants. Influence of the layers properties, such as roughness or contact angle, and the influence of their morphology on biocompatibility and osseointegration, as well as the influence of fixation and exploitation on the damage of the nanotubular oxide layer, are considered.

Characterisation of the nanotubular oxide layer formed on the ultrafine-grained titanium

Commercially pure titanium (cpTi) and titanium alloys are metallic implant materials usually used in dentistry and orthopaedics. In order to improve implant properties, Ti-based materials may be surface modified by different procedures. One of the most attractive methods is electrochemical anodization, as a method for obtaining nanotubular oxide layer on the material surface, aiming at improving mechanical, biological and corrosion properties of the metallic biomaterials. In the present study, ultrafine-grained titanium (UFG cpTi) was obtained by high pressure torsion (HPT) under a pressure of 4.1 GPa with a rotational speed of 0.2 rpm, up to 5 rotations at room temperature. In order to form homogeneous nanotubular oxide layer on the UFG cpTi, the electrochemical anodization was performed in phosphoric acid containing 0.5 wt. % of NaF electrolyte during anodizing times of 30, 60 and 90 minutes. The characterisation of thus formed nanotubes was performed using the scanning electron microscopy (SEM), while the surface topography was analysed using the atomic force microscopy (AFM). The results show that the electrochemical anodization process leads to an enhanced roughness of the surface. The mechanical behaviour of the UFG cpTi after the electrochemical anodization process is estimated using the nanoindentation technique. Obtained results show that anodized material has lower value of nanohardness than non-anodized material. Moreover, anodized UFG cpTi has lower modulus of elasticity than non-anodized UFG cpTi and the value is close to those observed in bones.

Role of Heat Treatment on the Fabrication and Electrochemical Property of Ordered TiO2 Nanotubular Layer on the As-Cast NiTi

We investigated the effect of various heat treatment processes on the formation and electrochemical properties of ordered TiO2 nanotubes (TNTs) on NiTi. In this respect, after solution treatment of as-cast NiTi samples at 900 °C for 1 h, four different heat-treated groups were examined consisting of furnace-cooled sample, water-quenched sample, water-quenched/300 °C-aged treated (300T-NiTi) and water-quenched/500 °C-aged treated (500T-NiTi) samples. Consequently, heat-treated samples were anodized in ethylene glycol solution containing NH4F. Results showed that the microstructure, chemical composition and grain size of the NiTi samples depended on the heat treatment process. Water-quenching and subsequent aging process provided fine precipitations distributed in the grain boundaries and reduced grain size. Furthermore, it was found that TNTs with various distributions and microstructures could be developed depending on the heat-treatment process of NiTi samples as well as anodization voltage and time. Noticeably, anodization of 500T-NiTi samples resulted in formation of well-distributed TNTs with diameters of 30 ± 5 nm. Moreover, heat-treatment process as well as TNT formation resulted in significantly enhanced corrosion resistance of as-cast NiTi substrate and reduced Ni release, depending on the treatment process. Regarding potential applications, anodization of water-quenched and 500 °C aged treated NiTi at 50 V for 10 min could provide nano-scaled biofunctional coating to promote the biological applications of NiTi implants.

Electrochemical Formation of Self-Organized Nanotubular Oxide Layers on Niobium (Review)

Background: This mini-review paper is focused on the anodic formation of selforganized nanotubular oxide layers on niobium as a nontoxic and allergy-free metallic biomaterial. Objective: The main purpose of the work was to outline the research activities being undertaken on the electrochemical modification of niobium to obtain its porous oxide with enhanced biocompatibility. Method: The effect of various parameters, such as concentration of fluoride anions in electrolyte, pH of electrolyte, and current-voltage-time conditions on the anodic formation of Nb2O5 nanotubes, was summarized. Results: Thirty-seven references were included in this mini-review and they were divided into main five parts. First part outlined the electrochemical formation of self-organized nanotubular oxide layers on niobium via anodic oxidation. The mechanism of the electrochemical formation of niobium oxide nanotubes was discussed. Second part presented the influence of the electrolyte type used for anodic oxidation of niobium and the fluoride ion concentration in the electrolyte on the type and dimensions of the obtained oxide niobium nanotubes. The influence of the applied voltage during anodic oxidation of niobium on the morphological parameters of the formed nanotube arrays was described in third part. The importance of the selection of the electrolyte pH for tailoring the length of niobium oxide nanotubes was demonstrated in fourth part. The last part outlined the structure of niobium oxide nanotubes. Conclusion: Key results were extracted and reviewed from publications of research activity in anodic oxidation of niobium introduced basics of that process and the current trends in electrochemical improvement of biocompatibility of metallic nanobiomaterials were presented. Keywords: Anodic oxide, anodization, electrochemical modification, nanotubes, niobium, oxide layers.

Nanotubular Oxide Layers and Hydroxyapatite Coatings on Porous Titanium Alloy Ti13Nb13Zr

Abstract The surface condition of an implant has a significant impact on response occurring at the implant-biosystem border. The knowledge of physical-chemical and biological processes allows for targeted modification of biomaterials to induce a specified response of a tissue. The present research was aimed at development of technology composing of obtaining the nanotube oxide layers on a porous titanium alloy Ti13Nb13Zr, followed by the deposition of phosphate coating. The porous substrate (porosity about 50%) was prepared by a selective laser melting of the Ti13Nb13Zr powder with the SLM Realizer 100 equipment. The nanotubular oxide layers were fabricated by electrochemical oxidation in H3PO4 + 0.3% HF mixture for 30 min. at a constant voltage of 20V. The calcium phosphate coatings were formed by the electrochemically assisted deposition (ECAD). The presence of nanotubular oxide layers with their internal diameters ranging from 30 to 100 nm was observed by SEM (JEOL JSM-7600F). The nanotubes have dimensions that facilitated the deposition of hydroxyapatite.

Wettability of nanotubular titania layers for biomedical applications developed by electrochemical anodization

The titania nanotubes (TNT) were synthesis on Ti6Al4V alloy planar surfaces with different initial preparation: polished, turned, acid etched, and SLA (sand blasted with large grits and acid etched), by electrochemical anodization performed in phosphate/fluoride based electrolyte, using anodization potentials of 20 V or 24 V. The morphology of developed layers was investigated by scanning electron microscopy (SEM) and consists in highly ordered, self-arranged TiO2 nanotubes of 25-110 nm in diameter. The initial and modified surfaces’ wettability was evaluated by static contact angle method and drop shape analysis. The contact angle measured on modified surfaces with TNT developed on polished surfaces is 70° showing moderate hydrophilic properties, while the contact angle measured on TNT layers developed on micro rough surfaces (turned, acid etched, SLA) is lower, showing the enhancement of surfaces wettability. Turned surfaces covered with TNT exhibits a contact angle of 60°, on SLA surfaces modified with TNT layers contact angle is 47°, while the best wettability, demonstrated by a contact angle of 35°, is showed by acid etched surfaces covered with TNT layers.

(Invited) Growth of Anodic Nanotubular Oxides: The Influence of Substrate

In the present work, we examined the growth of nanotubular oxide layers by anodization in fluoride containing electrolytes, focusing on the influence of substrate. The properties of substrate such as defect density and the size of microstructure were varied. The defect density and the size of microstructure were controlled by cold work and heat-treatment. Cold work increased the defect density of Ti substrate whereas heat-treatment decreased the defect density within Ti. These substrates were subjected to the anodization in ethylene glycol containing ammonium fluoride and water. Cross-sectional observations revealed that the defect density affected the growth of nanotubular oxide layers on Ti substrate, that is, on Ti substrate with increased defect density by cold work, the thickness of nanotubular oxide layer increased while on Ti substrate with decreased defect by heat treatment, the thickness decreased. The size of microstructure also exhibited strong influence on the growth of nanotubular oxide layer. For this purpose, lamellar Ti-41at.%Al alloys consisting of Ti3Al and TiAl were prepared. The width of the lamellas was controlled by heat treatment. On the alloy with wider lamellas, nanotubular oxide layers were formed on each phase. On the other hand, selective growth of pore was achieved when the width of lamella was below critical size. Therefore, these results indicate that the properties of substrate strongly affect the growth of anodic nanotubular oxide layers.