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In this study, nanotube morphology changes of Ti- x Ta-Ag-Pt alloys with Ta content for biomaterials were researched using various experimental instruments. Ti- x Ta-Ag-Pt alloys were manufactured in an Ar atmosphere using a vacuum arc-melting furnace with Ta contents of 10 and 50, and then heat-treated at 1100 °C for 1 hr. Nanotube formation of Ti- x Ta-Ag-Pt ( x = 10, 50 wt%) alloys were performed using a DC power of 30 V in 1.0 M H₃PO₄ + 0.8 wt% NaF electrolyte solution. Surface characteristics were investigated using an optical microscope, X-ray diffractometer, field-emission scanning electron microscope, energy-dispersive X-ray spectroscopy, and Image analyzer (Image J). Ti-10Ta-Ag-Pt alloy had a needle-like structures, and Ti-Ti-50Ta-Ag-Pt showed the mixed structure (equiaxed and needle-like structures). As the Ta content increased, the α -phase decreased and the β -phase increased. The highly ordered nanotubes were formed on the β -phase, whereas disordered nanotubes were formed on needle-like structure of α -phase in Ti-10Ta-Ag-Pt alloy. As the Ta content increases, large and small nanotube diameters became smaller in size. Anatase and rutile phases were formed on the alloy surface. Ta, Ag, and Pt elements were uniformly distributed over the entire surface and at the edge or inside of the nanotube.

The purpose of this study was to investigate the control of nanotube morphology using various factors for dental implant. TiO2 nanotube formation on biomedical grade α+β type Ti-6Al-4V alloy was investigated using anodization technique as a function of applied DC potential (10 V to 30 V and 30 V to 10 V) and anodization time for 60 min in 1 M H3PO4 with small additions of NaF (0.5 wt.%, and 0.8 wt.%). The microstructure and phase characteristics of surface were examined by optical microscopy, field emission scanning electron microscopy and X-ray diffraction. Also, in order to observe the biocompatibility and surface roughness, wettability and atomic force microscopy of alloy was measured.

The purpose of this study was to investigate the biocompatibility of Ti-30Nb-7Ta alloy surface decorated with TiO2 nanotubes by anodization in an electrolyte containing 1 M H3PO4 and 0.8 wt.% NaF with an applied voltage of 10 V for 2 h. The anodization was carried out using a scanning potentiostat. The microstructures of alloys and morphology of the nanotubes were investigated by optical microscopy, field emission scanning electron microscopy, and X-ray diffractometry. In comparison to the Ti-30Nb-3Ta alloy, the Ti-30Nb-7Ta alloy contained a lower amount of α" phase, while the β phase was higher. In this study, we observed the formation of a spongy porous layer on the Ti-30Nb-7Ta alloy, while the Ti-30Nb and Ti-30Nb-3Ta alloys showed an absence of such a spongy layer.

The purpose of this study was to investigate nanotube nucleation phenomena on the Ti-25Ta-xZr alloys for implant materials, using an anodic titanium oxide (ATO) technique. Ti-25Ta-(0 wt.%-15 wt.%) Zr alloys were prepared using a vacuum arc-melting furnace. The Ti-25Ta-xZr alloys were then homogenized for 12 hr at 1000 degrees C, followed by water quenching. Formation of the nanotubular oxide surface structure was achieved initially on the Ti-25Ta-xZr alloys by anodization in a 1 M H3PO4 electrolyte containing 0.8 wt.% NaF at room temperature, using a potentiostat. After the first formation of the nanotubes was achieved, this initial nanotube layer was eliminated, and further anodization was carried out repeatedly. The microstructure, phase transformation, and morphology of nanotubular Ti-25Ta-xZr alloys and the process of nanotube growth using this ATO method were analyzed by X-ray diffraction, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. Microstructures of the Ti-25Ta-xZr alloys changed from α" phase to β phase. Nanotubes formed with the ATO technique had pit-like top holes, with thinner walls and lower contact angle, compared to the initially formed nanotubes.

To improve bone tissue integration on implant surfaces, nanotube formation and laser texturing techniques have been used to increase the roughness of the implant surfaces. In this study, surface film of nanotube/micropit formed Ti-3ONb-xZr and Ti-30Ta-xZr alloy with low elastic modulus have been investigated using field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscope (EDS). The alloying elements can play role in controlling the nanotube shape and micropit shape, the highly ordered nanostructure, and contact angle for biocompatibility.

The aim of the present study is to produce and characterize a well-controlled surface texture on Ti-35Nb-xHf alloys to promote osseointegration. Ti-35Nb-xHf (x = 0, 3, 7 and 15 wt.%) alloys were prepared by arc melting and heat treated for 12 hr at 1000 degrees C in an argon atmosphere and then water quenching. For surface texturing, an amplified Ti: sapphire laser system was used for generating 184 femtosecond (FS, 10(-15) sec) laser pulses with the pulse energy over 30 mJ at a 1 kHz repetition rate with a central wavelength of 800 nm. The nanotube formation was achieved by anodizing a Ti-35Nb-xHf alloy in H3PO4 electrolytes containing 0.8 wt.% NaF at room temperature. The surface morphology of nano/micro structure will enhance osseointegration and cell adhesion.

Titanium and its alloys are widely used as a dental implant material in clinical dentistry and as an orthopedic implant materials due to their good mechanical properties, corrosion resistance, and biocompatibility. In this study, nanotubular oxide surface and layer formed on the Ti-35Ta-xZr alloys for biomaterials have been investigated by using electrochemical methods. Ti-35Ta-xZr alloys were prepared by arc melting and heat treated for 24 hr at 1000 degrees C in argon atmosphere, and then water quenching. Ti oxide nanotubes were formed on the Ti-35Ta-xZr alloys by anodizing in H3PO4 containing 0.8 wt% NaF solution at 25 degrees C. Anodization was carried out using a scanning potentiostat. Microstructures of the alloys and nanotube surface were examined by FE-SEM, EDX, and XRD. Crystallization treatment of nanotube surface was carried out for 3 hr at 450 degrees C. Microstructures of the Ti-35Ta-xZr alloys were changed from beta phase to alpha'' phase, and changed from an equiaxed to a needle-like structure with increasing Zr content. Nanotubular oxide surface and layers consisting of highly ordered nanotubes with a wide range of diameters (approximately 150-200 nm) and lengths (approximately 4-10 microm) can be formed on alloys in the Ti-35Ta-xZr alloys with Zr content. As the Zr content increased from 3% to 15%, length of step between the bamboo knob-like had increasing values of approximately 50 nm, 80 nm, and 140 nm, respectively. The nanotubes formed on the Ti-35Ta-xZr alloy surface were amorphous structure before heat treatment, but oxide surface had mainly an anatase structure by heat treatment.

This work reports the corrosion behavior of nanotubular oxide layers on Ti-29Nb-xZr alloys with different compositions by anodization in 1 M H3PO4 + 0.8 wt% NaF. Depending on the alloy composition, nanoporous or highly ordered nanotube structures can be formed. The nanotube oxides on the Ti-29Nb-xZr alloy showed lower corrosion current density compared to non-treated sample.

Highly ordered nanotube oxide layers were developed on low rigidity quaternary beta-type Ti-35Nb-5Ta-7Zr alloy by controlled anodic oxidation in electrolyte containing 1 M H3PO4 and 0.5 wt% NaF at room temperature. The diameters of the nanotubes formed were in the range of 30 to 80 nm. Electrochemical corrosion behavior of the nanotubular alloy was studied in Ringer's solution at 37 +/- 1 degrees C using potentiodynamic polarization and AC Impedance. The result of the study showed that nanotube formation on the surface affect the passivation behavior of the quaternary alloy significantly. However the corrosion current density was considerably higher for the nanotubular alloy.

Ti-30Nb-xZr and Ti-30Ta-xNb alloys have been investigated using various methods of surface nanotube formation. Ternary Ti-30Nb-xZr (x = 3 and 15 wt%) and Ti-30Ta-xNb (x = 3 and 15 wt%) alloys were prepared by using high-purity sponge Ti (Grade 4, G&S Titanium, USA), Ta, Zr and Nb spheres. The two groups of ternary Ti alloys were prepared using a vacuum arc melting furnace. Nanotube formation was carried out with a conventional three-electrode configuration with the Ti alloy specimen, a platinum counterelectrode, and a saturated calomel (SCE) reference electrode. Experiments were performed in 1 M H3PO4 with small additions of NaF (0.1-0.8 wt%), using a potentiostat. Nanotubes formed on the surfaces of the two ternary Ti alloys were examined by field emission scanning electron microscopy, EDS and XRD. The Ti-30Ta-xZr alloys had microstructure with entirely needle-like constituents; the thickness of the needle-like alpha-phase increased as the Zr content increased. The Ti-30Nb-xZr alloys had equiaxed microstructures of the beta-phase, and increasing amounts of the needle-like alpha phase appeared at the grain boundaries of the beta-phase as the Zr content increased. The nanotubes were nucleated and grew mainly on the beta phase for the Ti-30Ta-3Zr and Ti-30Nb-3Zr alloys, which had nanotubes with uniform shape, but the nanotubes were nucleated at the alpha phase for the Ti-30Ta-15Zr and Ti-30Nb-15Zr alloys, which had nanotubes with irregular shape and diameters of two sizes. The diameter and depth of the nanotubes could be controlled, depending upon the alloy composition and composition of the surface oxide films (TiO2, Nb2O5, Ta2O5, and ZrO2). It is concluded that this research that selection of the appropriate alloying element can allow significant control of the nanotopography of these Ti alloy surfaces and that it is possible to control the surface nanotube size to promote long-term osseointegration for clinical dental or orthopedic use.

Surface modification of dental implants or orthopedic implants is important for biocompatibility, and Ti-6Al-4 V alloy is mainly used as implant material for clinical use. In particular, research on the formation of nanotubes for drug doping to improve biocompatibility is in progress. For the control of nanotube shape, in this study, nanotube shape changes on Ti-6Al-4 V alloy via various applied potential for bio-implants were researched using various instruments. The formation of nanotubes on the surface of the Ti-6Al-4 V alloy was performed using a DC power source as a two-electrode system, and platinum as a counter electrode and a working electrode as an anode. The electrolyte was 0.8 wt. % NaF solution and 1.0 M H3PO4 were used and mixed using a magnetic bar during anodization. At this time, the voltage applied when forming the nanotubes was varied as (10 → 20 → 30 V), (30 → 10 → 30 V), and (10 → 30 → 30 V), respectively, and these voltages were applied for 30 min for each step. After the formation of nanotubes, the surface morphology and structural properties of the samples were observed using field-emission scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectroscopy, and nanoindentation tester. The higher the voltage applied during the formation of nanotubes, the larger is the diameter. In the case of the nanotube (10 → 20 → 30 V), the top of the nanotube was narrow and the diameter increased toward the bottom, forming a cone shape. In the case of the nanotube (30 → 10 → 30 V), a narrow waist shape was formed, and in the case of the nanotube (10 → 30 → 30 V), a jar shape was formed with anatase and rutile phases. From the FT-IR results, when nanotubes are formed, TiO2 anatase was detected and showed the tendency to change from crystallization to amorphous state. The indentation hardness and elastic modulus decreased for the nanotube surface compared with those of the bulk Ti alloy. [ABSTRACT FROM AUTHOR]

In general, Ti alloys are commonly used as biomaterials for implants. However, in the case of such alloys, the high elastic modulus causes stress shielding effects and bacterial growth, reducing their biocompatibility. In order to improve it, new alloys composed of Ti–Nb–Ag–Pt were developed in this study because it is possible to reduce the elastic modulus by adding an alloying element, such as Nb, and to reduce the bacterial activity by adding Ag and Pt elements. The following studies were conducted with the aim of manufacturing and forming nanotubes on the surface to greatly improve the biocompatibility. Ti–xNb–Ag–Pt alloys were manufactured using a vacuum arc furnace in an Ar atmosphere, homogenized for 1 h at 1050 °C, and then quenched at 0 °C. The formation of nanotubes on the surfaces of the alloys was performed using the anodization method with an applied voltage of 30 V in 1 M H3PO4 + 0.8 wt% NaF for 1 h at 25 °C. The formed nanotube surfaces were analyzed by optical microscopy, field emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, nanoindentation tests, and antibacterial tests. Antibacterial activity was evaluated according to the ISO 22196:2007 method, for which S. aureus (NBRC122135) was used. The microstructure of Ti–10Nb–Ag–Pt was a needle-like structure, and Ti–50Nb–Ag–Pt presented both an equiaxed structure and a needle-like structure. The size of the nanotube diameter decreased as the Nb content increased. The Ag and Pt elements were evenly distributed on the nanotube-formed alloy surfaces. The Vickers hardness and the elastic modulus value decreased as the Nb content increased. Following the nanotube formation, the Vickers hardness and elastic modulus values decreased by thrice, and only the nanotube-formed Ti–xNb alloys containing Ag and Pt showed the antibacterial activity effect. [ABSTRACT FROM AUTHOR]

In this work, surface observation of nanotube-formed titanium by anodization in an electrolyte containing hydroxyapatite nanoparticles was carried out using FE-SEM and analyzed by XPS in order to determine changes in the chemical states of elements through depth profiling. The anodized layer consisted of three regions: (1) a TiO 2 layer adjacent to titanium , (2) an intermediate barrier layer of TiO 2 nanotubes, and (3) a surface hydroxyapatite [HAp, Ca 10 (PO 4) 6 (OH) 2 ] layer. The nanotube-formed surface consisted of the anatase TiO 2 phase. The HAp layer that formed on the TiO 2 nanotube film grew vertically, and the electrodeposited HAp nanoparticles were distributed on the whole surface. From comparative analyses of the depth profile before Ar+ ion sputtering and after 4 keV Ar+ ion sputtering, the multilayer contained Ti, O, Ca, and P, and showed no noteworthy difference. The Ti-2p, O-1s, Ca-2p, F-1s, C-1s, and N-2s transitions were continuously detected in the multilayer as the sputtering time increased. The dominance of the Ti-2p and O-1 s peaks, both before and after the Ar+ ion sputtering, shows that the surface consists mainly of an oxidized TiO 2 layer. The Ca-2p and P-2p peaks were subsequently detected from HAp nanoparticles electrodeposited onto the TiO 2 nanotube film during an electrochemical reaction. The chemical states of calcium and phosphate in the multilayer were similar to those in HAp. • Nanoparticles created by anodization on nanotube-formed titanium were investigated. • The anodized multilayer consisted of a cell base, a barrier layer, TiO 2 nanotubes, and a hydroxyapatite layer. • Ti, O, Ca, and P in the multilayer showed no notable differences in proportions before and after Ar + sputtering. • Transitions for Ti-2p, O-1s, Ca-2p, F-1s, C-1s, and N-2s were continuously detected by XPS in the multilayer. • The chemical states of calcium and phosphate in the multilayer were similar to those in hydroxyapatite. [ABSTRACT FROM AUTHOR]

Highlights • In this study, evaluation of bone formation on ultra-fine structures in simulated body fluid was researched. • Coarse protrusions, including HAp nanoparticles were regularly deposited onto the TiO 2 barrier layer. • The narrow spectrums for Ti 2P, Ca 2p, and P 2p were similar, depending on the characteristics of the electrolyte solution. • Apatite morphologies were well-formed onto the modified surface according to the different times. Abstract Surface modifications are commonly utilized to adjust the properties of titanium and its alloy surface to the specific needs of medical applications, but there are disadvantages such as poor osteoconductive properties and low adhesion of bone cells to the implant surface. To overcome these limitations, the surface properties affecting osseointegration during implantation must be altered. In this study, we applied a new method for improving surface modifications based on the characteristics of an electrolytic solution. In electrolyte solution containing NaF in Na 2 SO 4 , uniform TiO 2 nanopores formed and HAp nanoparticles were electrodeposited around the TiO 2 nanopores. In the electrolyte solution containing NH 4 F in (NH 4)H 2 PO 4 , coarse protrusions, including HAp nanoparticles, were regularly deposited onto the TiO 2 barrier layer. The surface characteristics and distributed elements were investigated by energy-dispersive X-ray spectroscopy analysis, while analysis of the ultra-fine structure of the surface was carried out by field emission scanning electron microscopy. To investigate the behavior of the anion, chemical states were analyzed by X-ray photoelectron spectroscopy. The narrow spectra for Ti 2P, Ca 2p, and P 2p were similar and depended on the characteristics of the electrolyte solution. In addition, the Ca 2p spectrum showed two peaks for Ca 2p3/2 and 2p1/2 at 347.4 and 351.3 eV, respectively, which may be related to hydroxyapatite. Additionally, the P peak was deconvoluted into two peaks for P1/2 and P3/2 levels with binding energies of 134.2 and 133.4 eV, respectively. A soaking test showed that apatite morphologies were well-formed onto the modified surface at different times. [ABSTRACT FROM AUTHOR]

In this study, the effects of Hf content on the nanotubular structure of Ti-29Nb-xHf ternary alloys were investigated. The Ti-29Nb-xHf ternary alloys had Hf concentrations between 0 wt.% and 15 wt.% and were manufactured using a vacuum arc-melting furnace. Formation of a nanotube structure on these alloys was achieved by an electrochemical method in a 1 M H 3 PO 4 + 0.8 wt.% NaF electrolyte solution. The microstructures of the Ti-29Nb-xHf alloys changed from a needle-like structure to an equiaxed structure with increasing Hf content. The surface characteristics were analyzed by field-emission scanning electron microscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and a wettability test. The Ti-29Nb-xHf alloys had an equiaxed grain structure with α″ + β phases, and the α″ phase disappeared with an increase in the Hf content. The Ti-29Nb-15Hf alloy showed higher intensity β-phase peaks in the XRD patterns compared to Ti-29Nb-3Hf and Ti-29Nb-7Hf alloys. The average length of the nanotubes increased and the nanotubes became highly ordered as the Hf content increased. The contact angles of the surface with the nanotubes were lower than those of surfaces without nanotubes. [ABSTRACT FROM AUTHOR]

In this study, variations of nanotubes on the Ti–Nb–Hf alloys with applied voltages in dental applications were studied using different experimental techniques. Cone-shaped nanotubes were formed during the anodization of Ti–29Nb–xHf alloys by varying the applied DC voltage from 10 to 30 V, and from 30 to 10 V. The anodization time was 180 min and the electrolyte was 1 M H 3 PO 4 with 0.8 wt.% NaF. The morphology changes in anodized Ti–29Nb–xHf alloys were analyzed by optical microscopy, field emission scanning electron microscopy and X-ray diffractometer. The microstructures of the Ti–29Nb–xHf alloys changed from needle-like to an equiaxed structure, and with the increasing of Hf content, the β-phase gradually increased with a concomitant decrease in the α″-phase. Cone-shaped nanotubes were formed when the applied voltage was stepped up and the inversed cone-shape nanotube was formed on stepping down the applied voltage. The diameter, cross-section, length, and shape of the nanotube on the Ti–29Nb–xHf alloys can be controlled both by varying the applied voltage and the Hf content. [ABSTRACT FROM AUTHOR]

• Nanotube formation of Ti-6Al-4V alloy in electrolyte containing fluoride ion. • Uniform nanotube formed in alpha phase and irregular formed in β-phase of Ti-alloy. • Stable passivation formed on nanotube-formed surface, and corrosion resistance increased. • Corrosion occurred between α−phase and β phase. In this study, the nanotube formation and corrosion behavior of Ti-6Al-4V alloy with α - and β -phases were researched with various experimental instruments. For this study, nanotube formation on the sample was performed using the anodic oxidation method by applying a voltage of 30 V using a direct current power supply for 1 h using a 1.0 M H 3 PO 4 + 0.8 wt.% NaF solution at 25 °C. The corrosion properties of specimens were examined by potentiodynamic testing (potential range of -1000–1500 mV) in a 0.9% NaCl solution using a potentiostat. The nanotube morphology of the alloys was observed by field-emission scanning electron microscopy, X-ray diffractometry, and energy dispersive X-ray spectroscopy. The nanotubes in the α -phase were uniformly formed on the surface of the Ti-6Al-4V alloy, but nanotubes in the β -phase were irregularly formed. The nanotube-formed alloy had a wider passivation range and higher corrosion current density than the bulk alloy. The morphologies of the corrosion surfaces show that the edge trace around the β -phase was reduced, and the anatase phase increased on the corroded surface. In cross-sectioned nanotube layer after corrosion test, a deep pit was observed in the part where the nanotubes were removed. XRD analysis showed that the anatase and rutile phases were not formed in bulk alloys, but anatase and rutile phases were detected in the nanotube formed alloy, and the peak of the anatase increased on the corroded surface. From the result of potentiostatic test, the variation of current density from the beginning is almost the same, but the current density of the nanotube formed surface was slightly higher than that of non-nanotube formed surface with time. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to investigate the electrochemical characteristics of silicon-substituted hydroxyapatite coatings on the nanotube-formed Ti–35Nb–10Zr alloy. The silicon-substituted hydroxyapatite (Si–HA) coatings on the nanotube structure were deposited by electron beam-physical vapor deposition and anodization methods, and biodegradation properties were analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy measurement. The surface characteristics were analyzed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD). The Si–HA layers were deposited with rough features having highly ordered nanotube structures on the titanium alloy substrate. The thickness of the Si–HA coating was less than that of the HA coating. The XRD results confirmed that the Si–HA coating on the nanotube structure consisted of TiO2 anatase, TiO2 rutile, hydroxyapatite, and calcium phosphate silicate. The Si–HA coating surface exhibited lower Icorr than the HA coating, and the polarization resistance was increased by substitution of silicon in hydroxyapatite. [Copyright &y& Elsevier]

Abstract: To achieve excellent biocompatibility of metal-based implants, hydroxyapatite thin film coatings on nanotube-formed Ti–35Nb–10Zr alloys after femtosecond laser texturing have been investigated. Three groups of samples were prepared: (1) microtextured surfaces using femtosecond (FS) laser, (2) nanotube surfaces formed by anodization, and (3) hydroxyapatite coatings vapor-deposited by a physical electron beam method on the Ti–35Nb–10Zr ternary alloy. The surface morphology of the Ti–35Nb–10Zr alloys was examined by x-ray diffractometry, field-emission scanning electron microscopy, and energy-dispersive x-ray spectroscopy. To investigate ion release, potentiodynamic polarization testing was carried out in 0.9%NaCl solution, and wettability tests and MG 63 osteoblast-like cell culture studies were performed on the surfaces of the three groups to evaluate contact angle and cell growth morphology, respectively. The Ti–35Nb–10Zr alloys exhibited the equiaxed β phase structure. The FS laser-treated Ti–35Nb–10Zr alloys showed circular traces with diameters of 28±1.5μm and hole separations of 50μm, and the nanotubes formed on the surfaces had diameters of 180±15nm and compositions consistent with TiO2, Nb2O5, and ZrO2. The nanotube structure showed anatase, rutile and β-titanium diffraction peaks, whereas the HA-coated surface on the nanotubes showed hydroxyapatite, anatase and rutile peaks. The HA coatings displayed the desired role of decreasing the metal ion release with a lower current density value, and the nanotubes and FS laser-treated surface showed wider passive regions compared to other surfaces. The HA-coated surface on the nanotubes after FS laser texturing showed the lowest contact angle compared with the other surfaces. From FE-SEM observations, cell attachment and spreading of MG 63cells showed significantly higher tendency for surfaces covered by HA coating and nanotubes. [Copyright &y& Elsevier]

Abstract: In this paper, we investigated the electrochemical and surface behavior of hydroxyapatite (HA)/Ti films on the nanotubular Ti–35Nb–xZr alloy. The Ti–35Nb–xZr ternary alloys with 3–10wt.% Zr content were made by an arc melting method. The nanotubular oxide layers were developed on the Ti–35Nb–xZr alloys by an anodic oxidation method in 1M H3PO4 electrolyte containing 0.8wt% NaF at room temperature. The HA/Ti composite films on the nanotubular oxide surfaces were deposited by a magnetron sputtering method. Their surface characteristics were analyzed by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and an X-ray diffractometer (XRD). The corrosion behavior of the specimens was examined through potentiodynamic and AC impedance tests in 0.9% NaCl solution. From the results, the Ti–35Nb–xZr alloys showed a solely β phase microstructure that resulted from the addition of Zr. The nanotubular structure formed with a diameter of about 200nm, and the HA/Ti thin film was deposited on the nanotubular structure. The HA/Ti thin film-coated nanotubular Ti–35Nb–xZr alloys showed good corrosion resistance in 0.9% NaCl solution. [Copyright &y& Elsevier]

Abstract: In this study, we investigated the surface characteristics of the TiN/ZrN-coated nanotubular structure on Ti–35Ta–xHf ternary alloys for bio-implant applications. These ternary alloys contained from 3wt.% to 15wt.% Hf contents and were manufactured in an arc-melting furnace. The Ti–35Ta–xHf alloys were heat treated in Ar atmosphere at 1000°C for 24h, followed by water quenching. Formation of the nanotubular structure was achieved by an electrochemical method in 1M H3PO4 electrolytes containing 0.8wt.% NaF. The TiN coating and ZrN coating were subsequently prepared by DC-sputtering on the nanotubular surface. Microstructures and nanotubular morphology of the alloys were examined by FE-SEM, EDX and XRD. The microstructure showed a duplex (α′′+β) phase structure. Traces of martensite disappeared with increasing Hf content, and the Ti–35Nb–15Hf alloy had an entirely equiaxed structure of β phase. This research has shown that highly ordered, high aspect ratio, and nanotubular morphology surface oxide layers can be formed on the ternary titanium alloys by anodization. The TiN and ZrN coatings formed on the nanotubular surfaces were uniform and stable. The top of the nanotube layers was uniformly covered with the ZrN film compared to the TiN film when the Ti–35Ta–xHf alloys had high Hf content. [Copyright &y& Elsevier]

Abstract: Electrochemical characteristics of a titanium nitride (TiN)-coated/nanotube-formed Ti–Ta–Zr alloy for biomaterials have been researched by using the magnetic sputter and electrochemical methods. Ti–30Ta–xZr (x =3, 7 and 15wt%) alloys were prepared by arc melting and heat treated for 24h at 1000°C in an argon atmosphere and then water quenching. The formation of oxide nanotubes was achieved by anodizing a Ti–30Ta–xZr alloy in H3PO4 electrolytes containing small amounts of fluoride ions at room temperature. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. The microstructure and morphology of nanotube arrays were characterized by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The TiN coatings were obtained by the radio-frequency (RF) magnetron sputtering technique. The depositions were performed from pure Ti targets on Ti–30Ta–xZr alloys substrates. The corrosion properties of the specimens were examined using potentiodynamic test in a 0.9% NaCl solution by using potentiostat. The microstructures of Ti–30Ta–xZr alloys were changed from an equiaxed to a needle-like structure with increasing Zr content. The interspace between the nanotubes was approximately 20, 80 and 200nm for Zr contents of 3, 7 and 15wt%, respectively. The corrosion resistance of the TiN-coated on the anodized Ti–30Ta–xZr alloys was higher than that of the untreated Ti alloys, indicating a better protective effect. [Copyright &y& Elsevier]

Abstract: The nanotubular surface of Ti-binary and Ti-ternary alloys for biomaterials has been investigated using various methods of surface characterization. Binary Ti-xNb (x=10, 20, 30, and 40wt.%) and ternary Ti-30Ta-xNb (x=3, 7 and 15wt.%) alloys were prepared by using the high-purity sponges; Ti, Ta and Zr spheres. The nanotube on the alloy surface was formed in 1.0M H3PO4 with small additions of NaF (0.5 and 0.8wt.%), using a potentiostat. For cell proliferation, an MC3T3-E1 mouse osteoblast was used. The surface characteristics were investigated using field-emission scanning electron microscope, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. Binary Ti-xZr alloys had a lamellar and a needle-like structure, whereas, ternary Ti-30Ta-xZr alloys had equiaxed grains with a lamellar martensitic α′ structure. The thickness of the needle-like laths of the α-phase increased as the Zr content increased. The nanotubes formed on the α phase and β phase showed a different size and shape appearance with Zr content. As the Zr content increased from 3 to 40wt.%, the diameter of the nanotubes in Ti-xZr and Ti-30Ta-xZr alloy decreased from 200nm to 50nm. The nanotubular Ti-30Ta-15Zr alloy surface with a diameter of 50nm provided a good osseointegration; cell proliferation, migration and differentiation. [Copyright &y& Elsevier]

Nanotubular oxide layer formation on biomedical grade α + β type Ti–13Nb–13Zr alloy was investigated using anodization technique as a function of applied dc potential (10–40 V) and anodizing time (30–180 min) in 1 M H3PO4 + 0.5 wt% NaF at room temperature. The as-formed and crystallized nanotubes were characterized using SEM, XRD, and TEM. There was a bimodal size distribution of nanotubes with diameters at the range of 25–110 nm. Nanotubes nucleated on β matrix exhibited uniform surface appearance with circular morphology, whereas those nucleated on α phase yielded parabolic shape. TEM/EDS analysis detected the three component elements of the alloy in the nanotube. Heat treatment significantly altered the distinct interface between the nanotubes and the barrier oxide layer. [ABSTRACT FROM AUTHOR]

Abstract: Titanium and Ti alloys have been used extensively as bone-implant materials due to their high strength-to-weight ratio, good biocompatibility and excellent corrosion resistance. In this work, we have investigated the effects of the β-stabilizing element Nb on the morphology of nanotubes formed on Ti–xNb alloys using 1.0 M H3PO4 electrolyte containing 0.8 wt.% NaF and various electrochemical methods. Oxide layers consisting of highly ordered nanotubes with a wide range of diameters (approximately 55–220 nm) and lengths (approximately 730 nm–2 μm) can be formed on alloys in the Ti–xNb system as a function of Nb content. The nanotubes formed on the Ti–Nb alloy surface were transformed from the anatase to rutile structure of titanium oxide. The titanium oxide nanotube surface was observed to have lower corrosion resistance in 0.9% NaCl solution compared to titanium oxides surfaces on Ti–xNb alloys without the nanotube morphology. [Copyright &y& Elsevier]

Abstract: Nanotube morphology changes in Ti–Zr alloys as Zr content increases have been investigated. Ti–Zr (10, 20, 30 and 40 wt.%) alloys were prepared by arc melting and heat treated for 24 h at 1000 °C in an argon atmosphere. TiO2 nanotubes were formed on the Ti–Zr alloys by anodization in H3PO4 containing 0.5 wt.% NaF. Electrochemical experiments were performed using a conventional three-electrode configuration with a platinum counter electrode and a saturated calomel reference electrode. Samples were embedded in epoxy resin, leaving an area of 10 mm2 exposed to the electrolyte. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. Microstructures of the alloys were examined by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The Ti–Zr alloy microstructures observed by OM and FE-SEM changed from a lamellar structure to a needle-like structure with increasing Zr content. The microstructures also changed from β phase to increasing amounts of α phase as the Zr content increased. The number of large nanotubes formed by anodization decreased, and the number of small nanotubes increased, as the Zr content increased. The mean inner diameter ranged from approximately 150 to 200 nm with a tube-wall thickness of about 20 nm. The interspace between the nanotubes was approximately 60, 70, 100 and 130 nm for Zr contents of 10, 20, 30 and 40 wt.%, respectively. [Copyright &y& Elsevier]

Abstract: Highly ordered nanoporous and nanotubular oxide layers were developed on low-rigidity β Ti–35Nb–5Ta–7Zr alloy by controlled DC anodization in electrolyte containing 1M H3PO4 and 0.5wt.% NaF at room temperature. The as-formed and crystallized nanotubes were characterized by electron microscopy, energy-dispersive X-ray spectrometry and X-ray diffraction. The electrochemical passivation behavior of the nanoporous and nanotubular oxide surfaces were investigated in Ringer’s solution at 37±1°C employing a potentiodynamic polarization technique and impedance spectroscopy. The diameters of the as-formed nanotubes were in the range of 30–80nm. The nanotubular surface exhibited passivation behavior similar to that of the nanoporous surface. However, the corrosion current density was considerably higher for the nanotubular alloy. The surface after nanotube formation seemed to favor an immediate and effective passivation. Electrochemical impedance spectra were simulated by equivalent circuits and the results were discussed with regard to biomedical applications. [Copyright &y& Elsevier]

• Nanotube diameter and layer formed on Ti-alloy increased as applied voltage increased. • Hydroxyapatite- and Sr-coating layer was formed thicker than that of the HA coating layer. • Surface roughness of alloy increased in order of non-, HA and Sr-, and HA-coating. • Contact angle of HA- and Sr-coating increased, as applied voltage increased. In this study, morphology of hydroxyapatite and Sr coatings deposited using radio frequency- magnetron sputtering method on nanotube formed Ti-6Al-4V alloy was researched. For this study, nanotube formation on the samples was performed using anodization and then the hydroxyapatite (HA) and Sr thin film was coated using a RF magnetron sputtering system. For characterization of nanotube surface, the surface was observed using various instruments. The diameter of the nanotube increased and the nanotube layer increased as the applied voltage increased. The anatase phases were well formed on the surface and significantly increased as the applied voltage increased. HA and Sr coating layer was formed thicker than that of the HA coating layer and nanotubes were covered with HA and Sr. The surface roughness of the alloy increased as the voltage increased in the order of non-coating, HA and Sr coating, and HA coating. The contact angle of the alloy surface decreased in non-coating and HA coating, whereas, contact angle of HA and Sr coating increased as the applied voltage increased. [ABSTRACT FROM AUTHOR]

In this study, to improve the material properties and biocompatibility of Ti alloys, Ti-xNb-2Ag-2Pt alloy was prepared by adding niobium (Nb), silver (Ag), and platinum (Pt). The surface was treated by anodization, and surface treated alloy was coated with HA, Mg, and Si through magnetron sputtering. Ti-xNb-2Ag-2Pt alloys were based on a Ti-2Ag-2Pt alloy, and the Nb content was changed to 10, 30, and 50 wt%. The nanotubes were formed by anodization in 1 M H 3 PO 4 and 0.8 wt% NaF electrolyte, following which the sample was coated by RF-and DC-magnetron sputtering using HA, Mg, and Si targets. The surface morphology and material properties of Ti-xNb-2Ag-2Pt alloys were analyzed by optical microscopy (OM), nano-indentation tests, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometer (EDS), and X-ray diffractometer (XRD). In the case of Ti-xNb-2Ag-2Pt alloys, the martensitic and needle-like structure decreased and the equiaxed structure increased with increasing Nb content. The elastic modulus of Ti-50Nb-2Ag-2Pt alloys was lower than that of Ti-10Nb-2Ag-2Pt alloys. As the Nb content increased, the shape of the nanotubes changed irregularly and nanotube diameter of Ti-xNb-2Ag-2Pt alloys decreased. Also, nanotube diameter after co-sputtered Mg and Si on HA coated surface decreased compared to only HA deposited nanotubes. • Magnesium, silicon, and hydroxyapatite deposition on the Ti-xNb-2Ag-2Pt alloy by co-sputtering were studied. • The microstructure of Ti-xNb-2Ag-2Pt alloys changed from α to β phase, as the Nb content increased. • The elastic modulus and indentation hardness of Ti-xNb-2Ag-2Pt alloys was lower than that of Ti-6Al-4V alloy. • The shape of the nanotubes changed irregularly, and nanotubes diameter decreased, as Nb content increased. • The size of the nanotube holes after Mg and Si deposition decreased compared to HA deposited nanotube. [ABSTRACT FROM AUTHOR]

Abstract: In this study, photoelectrochemical analysis of bioactive material coated nanotubular surface of Ti–30Nb–xZr alloy has been investigated using a potentiostat and a Xenon lamp. Ternary Ti–30Nb–xZr(x=3, 15wt.%) alloys were prepared, and nanotube was formed using potentiostat in 1M H3PO4 +NaF(0.8wt.%). Hydroxyapatite (HA) was coated on nanotubular alloy by electron-beam physical vapor deposition (EB-PVD) method. The surface characteristics and photoelectrochemical behavior were investigated by FE-SEM, EDS, XRD and potentiostat. The microstructures of the Ti–30Nb–3Zr and Ti–30Nb–15Zr alloys showed an equiaxed grain structure with needle-like α phase in the β phase grains. The large nanotubes surrounded by smaller diameter nanotubes were formed with highly ordered surface on the Ti–30Nb–15Zr alloy. HA coated Ti–30Nb–15Zr surface has an irregular surface and flake-like particles with (211) and (112) crystalline planes. In the UV-irradiated Ti–30Nb–xZr alloy, the current density in the passive region was higher than that of non-UV-irradiated Ti–30Nb–xZr alloy, whereas for the nanotube surface the current density difference between UV-irradiated and non-UV-irradiated alloys was not significant. The Rp value of HA coated/nanotube surface under UV-irradiation was higher than that of the other surface. The phase angle of HA coated/nanotube surface was close to 60–70°. The study suggested that the photofunctionalization reaction strongly depends on the structure of oxide surface, crystallinity of hydroxyapatite and alloying elements. [Copyright &y& Elsevier]

The deposition of ultra-fine Pd/Ag/HAp nanoparticles onto TiO 2 nanotubes has been performed by an electrochemical method using a mixed electrolyte solution. Electrochemical deposition was carried out under constant voltage, and Pd/Ag/HAp nanoparticles were carefully added in the mixed electrolyte of 1.7 M (NH 4 )H 2 PO 4 + 0.4 M NH 4 F, which was slowly rotated by a magnetic stirrer on a hot plate in order to increase the diffusion rate of electrolyte ions. The electrochemical deposition behavior, chemical bonding state, and surface characteristics of the Pd/Ag/HAp nanoparticles have been investigated by FE-SEM, EDS, and XPS. The Pd/Ag/HAp nanoparticles were uniformly electrodeposited onto the whole top surface and around the tube walls, including the inner side and outer side, of the ultra-fine TiO 2 nanotubes. The ordered tubular structure was well-maintained without destruction during the electrochemical deposition process. With excessive activation up to a deposition time of 7200 s, continuous granular Pd/Ag/HAp nanoparticles gradually formed with a rough surface around the top of the TiO 2 nanotube layer. From the XPS and EDS analyses, Ti, Ca, P, Pd, and Ag were detected in the nanoparticles on the electrochemically deposited surfaces. The surface morphology after soaking in SBF exhibited hydroxyapatite-like precipitates, which consisted of the four elements Ti, O, Ca, and P, and having a Ca/P atomic ratio of 1.67. [ABSTRACT FROM AUTHOR]

Abstract: In this study, surface characteristics of hydroxyapatite(HA) coated Ti-30Ta-xZr and Ti-30Nb-xZr alloys after nanotube formation have been investigated by EB-PVD, FE-SEM, XRD and potentiostat. The microstructures of the Ti-30Ta-xZr alloy had a needle-like morphology, and the thickness of this needle-like structure increased as the Zr content increased. The microstructures of the Ti-30Nb-xZr alloy had an equiaxed grain structure. The nanotubes were mainly nucleated and grown at β phase in case of Ti-30Ta-3Zr, but nanotubes were nucleated at α phase in case of Ti-30Ta-15Zr alloy. The corrosion resistance of alloy increased as Zr content increased, and nanotubular surface with highly ordered small and large tubes was high corrosion resistant. The corrosion resistance of HA coated alloys after nanotube formation was higher than that of the non-HA coated nanotubular alloy. [ABSTRACT FROM AUTHOR]

Different applied potentials have been employed in a two-step anodization process, utilizing a 1 M H 3 PO 4 electrolyte and a solution containing this electrolyte and 0.8 wt.% NaF, to control the shape and morphology of oxide nanotubes on coatings for ternary Ti–30Ta–xZr alloys. The ternary alloys were manufactured using an arc furnace, and corrosion testing was carried out using a potentiostat. The microstructures of the Ti–30Ta–xZr alloys had a needle-like structure, and the lath thickness of the α′ phase increased as the Zr content increased. The microstructures of Ti–30Nb–xZr alloys had equiaxed grains. The Ti–30Nb–xZr alloys showed smaller micropores and nanotubes compared to the Ti–30Ta–xZr alloys. The Ti–Nb(Ta)–Zr alloys tended to have improved corrosion resistance with increasing Zr content. [ABSTRACT FROM AUTHOR]

Abstract: Surface phenomena of HA/TiN coatings on the nanotubular-structured beta Ti–29Nb–5Zr alloy for biomaterials have been investigated by several experimental methods. The nanotubular structure was formed by anodizing the Ti–29Nb–5Zr alloy in 1M H3PO4 electrolytes with 1.0wt.% NaF at room temperature. Hydroxyapatite (HA)/titanium nitride (TiN) films were deposited on Ti–29Nb–5Zr alloy specimens using a magnetron sputtering system. The HA target was made of human tooth-ash by sintering at 1300°C for 1h, and the HA target had an average Ca/P ratio of 1.9. The HA/TiN depositions were performed, using the pure HA target, on Ti–29Nb–5Zr alloy following the initial deposition of a TiN buffer layer coating. Microstructures and nanotubular morphology of the coated alloy specimens were examined by FE-SEM, EDX, XRD, and XPS. The Ti–29Nb–5Zr alloy substrate had small grain size and preferred orientation along the drawing direction. The HA/TiN coating was stable with a uniform morphology at the tips of the nanotubes. [Copyright &y& Elsevier]

Abstract: The purpose of this research is to study the morphology of hydroxyapatite coated nanotube surface of Ti–35Nb–xHf for implant materials using various experiments. For this study, Ti–35Nb–xHf (x=0, 3, 7 and 15 wt.%) alloys were prepared by arc melting and heat treated for 12h at 1000°C in an argon atmosphere and then water quenching. Nanotube formation on the Ti–35Nb–xHf alloys was achieved by anodizing in H3PO4 electrolytes containing 0.8wt.% NaF at room temperature. Anodization was carried out using an electrochemical method and all experiments were conducted at room temperature. Hydroxyapatite (HA) was deposited on the nanotubular Ti–35Nb–xHf alloys surface for the biomaterials by radio-frequency (RF) magnetron sputtering method. The morphologies of nanotubular and HA coated surface were characterized by X-ray diffractometer (XRD), optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM). The wettability of HA coated surface was measured by contact angle goniometer. The microstructure of Ti–35Nb–xHf alloys was transformed needle-like to equiaxed structure with Hf content and α″ phase decreased, whereas β phase increased as Hf content increased. HA coating surface was affected by microstructure of bulk and morphology of nanotube formation. In case of low Hf content, tip of nanotube formed at β phase was coated with HA film, whereas α″ phase was not coated with HA film. In case of high Hf content, nanotube surface was coated uniformly with HA film. The wettability of HA coated nanotubular surface was higher than that of non coated samples. [Copyright &y& Elsevier]

Abstract: In this paper, Ti–Hf (10, 20, 30 and 40 wt.%) alloys were prepared by arc melting, and subjected to heat treatment for 24 h at 1000 °C in an argon atmosphere. Formation of surface nanotubes was achieved by anodizing a Ti–Hf alloy in 1.0 M H3PO4 electrolytes with small amounts of NaF at room temperature. Microstructures of the alloys and nanotube morphology were examined by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The homogenized Ti–Hf alloys had a needle-like microstructure of α phase, and nanotubes formed on Ti–xHf alloys had the anatase phase after treatment that promoted crystallization. Uniform nanotubes formed for Hf contents up to 20 wt.%. Irregular nanotubes formed on the Ti–30Hf and Ti–40Hf alloys. The structure of the irregular layers on the Ti–30Hf and Ti–40Hf alloys had nanotubes of two sizes. Increasing the Hf content in Ti led to the formation of nanotubes with more narrow size. The pores in the nanotubes typically had a diameter ranging from 80–120 nm and a length of approximately 1.7 μm. It is concluded that nanotube morphology on Ti–Hf alloys can controlled by varying the amount of Hf. [Copyright &y& Elsevier]

Bioactive element coatings on nano-mesh formed Ti-6Al-4V alloy surface using plasma electrolytic oxidation were studied. Ti-6Al-4V alloy was used for nano-mesh formation, which was carried out in 1 M H 3 PO 4 + 0.8 wt% NaF at 30 V for 1 h. For micro-pore formation, plasma electrolytic oxidation (PEO) treatment was performed in a solution containing bioactive ions at 280 V for 3 min. After that, surface and biological characteristics were investigated using FE-SEM, EDS, AFM, Scratch test, XRD, wettability test, and MC3T3–1 cell culture test. The nanotubes and nano-mesh were well formed in the α-phase compared to β-phase. The many micro-sized pores on PEO(5ion) samples were formed with circular and irregularly shaped pores and the circular precipitate with oxide thickness of 2.0– 3.0 μm. PEO(5ion) and PEO(Ca + P) samples consisted of anatase and HA phases, and the surface roughness of the PEO samples was higher than those of nanotube and nano-mesh formed surface, whereas, the contact angle of the PEO samples was lower than those of nanotube and nano-mesh formed surface. The adhesive strength of the PEO(5ion) films showed higher compared to PEO(Ca + P) sample. The number of cells on the modified surface and oxide layers increased with the surface roughness. The cell growth and proliferation on the PEO(5ion) films were higher than those of polished surface, the adhesion of cells is greatly improved on the nano-mesh surface. • Bioactive coatings on nano-mesh formed Ti alloy via plasma electrolytic oxidation were researched. • Nano-mesh was formed in the alpha phase, but not as well formed in the beta phase. • Surface roughness and wettability of the PEO samples was higher than those of nano-mesh formed surface. • The cell growth and proliferation on the PEO(5ion) films were higher than those of polished surface. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the highly ordered nanotubular film formation on Ti–25Nb–xZr and Ti–25Ta–xHf, examining the roles of niobium, zirconium, tantalum and hafnium alloying elements. The Ti–25Nb–xZr and Ti–25Ta–xHf ternary alloys contained 0, 7 and 15 wt.% of these alloying elements and were manufactured using a vacuum arc-melting furnace. Cast ingots of the alloys were homogenized in Ar atmosphere at 1050 °C for 2 h, followed by quenching into ice water. Formation of nanotubular films was achieved by an electrochemical method in 1 M H 3 PO 4 + 0.8 wt.% NaF at 30 V and 1 h for the Ti–25Nb–xZr alloys and 2 h for the Ti–25Ta–xHf alloys. Microstructures of the Ti–25Ta–xHf alloys transformed from α″ phase to β phase, changing from a needle-like structure to an equiaxed structure as the Hf content increased. In a similar manner, the needle-like structure of the Ti–25Nb–xZr alloys transformed to an equiaxed structure as the Zr content increased. Highly ordered nanotubes formed on the Ti–25Ta–15Hf and Ti–25Nb–15Zr alloys compared to the other alloys, and the nanotube layer thickness on Ti–25Ta–15Hf and Ti–25Nb–15Zr was greater than for the other alloys. Nanotubes formed on Ti–25Ta–15Hf and Ti–25Nb–15Zr showed two sizes of highly ordered structures. The diameters of the large nanotubes decreased and the diameters of the small nanotubes increased as Zr and Hf contents increased. It was found that the layer thickness, diameter, surface density and growth rate of nanotubes on the Ti–25Ta–xHf and Ti–25Nb–xZr alloys can be controlled by varying the Hf and Zr contents. X-ray diffraction analyses revealed only weak peaks for crystalline anatase or rutile TiO 2 phases from the nanotubes on the Ti–25Nb–xZr and Ti–25Ta–xHf alloys, indicating a largely amorphous condition. [ABSTRACT FROM AUTHOR]

Abstract: The deposition and morphology of hydroxyapatite (HA) nanoparticles on nanotube-formed Ti–Nb–Zr alloys for dental implants has been investigated utilizing electrochemical, field-emission scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) methods. Ti–29Nb−xZr ternary alloys with 3 and 15 wt.% Zr content were prepared by arc melting. Nanotubular oxide layers were formed on these alloys by an anodic oxidation method in 1 M H3PO4 electrolyte containing 0.8 wt.% NaF at room temperature. Hydroxyapatite coatings were deposited onto the nanotubular surfaces via an electrochemical method (pulsed current). The HA layers were well-deposited and contained features of the underlying nanotube structure; observed morphologies consisted of particles, a mixture of particles and plate-like shapes, and entirely plate-like shapes. This variation in morphology occurred with an increasing number of deposition cycles and increases in Ca and P concentrations in the electrolyte. X-ray diffraction revealed that the nanotubular coating contained the anatase form of TiO2, and FTIR indicated that the electrochemically deposited calcium phosphate layer contained HPO4 2−, PO4 3−, H2O, and OH− indicative of the HA composition. [Copyright &y& Elsevier]