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In this study, to reactivate the oxide film and to secure biocompatibility, plasma electrolytic oxidation (PEO) treatment and hydroxyapatite (HA) deposition via mechanical coating (MC) processes were investigated. This experimental approach involved subjecting the Ti–6Al–4V alloy specimens to PEO treatment, followed by MC with HA powder for different hours as HA has the potential to increase bioactivity and surface characteristics due to its chemical composition and structural properties similar to natural bone. Therefore, the study aimed to examine the effects of MC with HA powder for 0, 1, 3, 5, 7, and 9 h on PEO-coated Ti–6Al–4V alloy discs for analyzing the surface characterization, phase analysis, surface roughness, wettability, adhesion strength, hardness, corrosion behavior, and cell proliferation properties for dental implant use. The findings demonstrate that prolonged HA milling enhances the substrate's mechanical strength, corrosion resistance, and adhesion properties. The presence of prominent anatase and HA peaks, particularly in the 5 MC-PEO, 7MC-PEO, and 9 MC-PEO samples, validates the synergistic impact of the PEO oxide layer and HA milling, resulting in outstanding corrosion resistance and biocompatibility. Cell culture analysis reveals a positive correlation between increased milling time and enhanced cell proliferation, particularly towards small-sized HA particles. [Display omitted] [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: The aim of this study was to investigate the hydroxyapatite coating on the Ti–35Nb–xZr alloy by electron beam-physical vapor deposition. The Ti–35Nb–xZr ternary alloys contained from 3wt.% to 10wt.% Zr content were manufactured by arc melting furnace. Hydroxyapatite (HA) coatings were prepared by electron-beam physical vapor deposition (EB-PVD) method, and crystallization treatment was performed in Ar atmosphere at 300 and 500°C for 1h. The coated surface morphology of Ti–35Nb–xZr alloy was examined by FE-SEM, EDX and XRD, respectively. In order to evaluate the corrosion behavior, the tests were performed by potentiodynamic, cyclic polarization and AC impedance test. All the electrochemical data were obtained using a potentiostat. The Ti–35Nb–xZr alloys exhibited equiaxed structure with β phase, the peak of β phase increased with Zr contents. The hardness and elastic modulus of Ti–35Nb–xZr alloys decreased as Zr content increased. The HA coated layer was approximately 150nm and Ca/P ratio of HA coated surface after heat treatment at 500°C was around 1.67. The HA thin film consisted of small droplets with spherical shape by crystallization. From the anodic polarization curves, HA coated and heat treated Ti–35Nb–10Zr alloy showed higher corrosion potential than other samples. HA coated film on the Ti–35Nb–10Zr alloy can be shown high polarization resistance by crystallization. [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, bone-like apatite formation on manganese-hydroxyapatite (Mn-HA) coatings formed on Ti-6Al-4V by plasma electrolytic oxidation (PEO) has been investigated by several techniques. Ti-6Al-4V ELI disks were used as substrates for PEO treatment. Test specimens were used as anodes, and a Pt rod was used as the cathode in an electrolytic solution containing Mn. The applied voltage was 280 V, and the deposition time was 3 min. To examine the bioactivity, the PEO films formed on Ti-6Al-4V were immersed in SBF for 12 h. The PEO films and the Ti-6Al-4V surface after immersion in SBF were characterized by a thin-film X-ray diffractometer, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. The PEO surface presented large and irregular pores, and the number of pores increased as the Mn content increased. For the PEO-treated samples, anatase peaks were detected by X-ray diffraction, and the HA peak intensity increased as the Mn content increased. The Ca/P ratio decreased, whereas the (Ca + Mn)/P ratio increased, as the Mn content increased. The coatings without Mn on the micropores had a small granular shape, and the pores were covered with HA after the immersion in SBF. As the Mn concentration increased, all Mn-HA coating surfaces became more dense, and microcracks appeared on the coating surface. [ABSTRACT FROM AUTHOR]

Electrochemically-coated hydroxyapatite films on nanotubular Ti Nb alloys prepared in solutions containing Ca, P, and Zn ions were explored for dental applications using various experimental methods. Ti-xNb binary alloys were used in this study. Homogenization treatment of samples was carried out at 1000 °C for 2 h, followed by quenching in 0 °C water. Self-organized nanotubular TiO 2 was prepared by electrochemical oxidation of the samples in 1.0 M H 3 PO 4 + 0.8 wt.% NaF electrolyte at anodization potential of 30 V, for 1 h. Electrochemical deposition of pure HA and Zn-doped HA on the alloys was conducted at 85 °C in electrolytes containing Zn ions. The Zn-HA films, along with the nanotubes, were characterized via X-ray diffraction, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). The Ti-xNb alloys underwent structural transformation from the α″ + β phases to β phase with a large grain size as the Nb content increased. The nanotubular structure of Ti 30Nb and Ti 50Nb alloys had highly ordered diameter distributions consisting of two distinct diameters. The nanotubular surface was covered with precipitated HA and Zn-HA, and the plates of HA became increasingly larger with smaller particles surrounding the pores as the Nb content of the alloy increased, leading to eventual loss of the nanotube pores. In the case of the Zn-HA coating, the entire surface showed a uniform distribution of elements on the nanotube surface. [ABSTRACT FROM AUTHOR]

Hydroxyapatite deposition on micropore-formed Ti-Ta-Nb alloys by plasma electrolytic oxidation for dental applications was investigated. Ti-35Ta-xNb alloys (x = 0 and 10 wt.%) were prepared with an arc-melting furnace. Micropores were formed on the Ti-35Ta-xNb alloys in 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at 280 V for 3 min. Hydroxyapatite deposition were carried out on the alloy surfaces using cyclic voltammetry in 2.5 mM Ca(NO 3 ) 2 ∙ 4H 2 O + 1.5 mM NH 4 H 2 PO 4 solution with various deposition cycles. Morphology and structure of the alloy surfaces and hydroxyapatite were investigated by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The microstructure of Ti-35Ta-xNb alloys showed the α″ and β phases, and the XRD peak for the β phase increased with Nb content. For the non-NaOH treated surface, the morphology of HA deposited on Ti-35Ta-xNb alloys showed a plate-like shape, whereas the HA particle shape on the micropore-structured Ti-35Ta-xNb alloys was flower-like. The pore size and thickness of the surface barrier layer increased as the voltage increased. The fraction of rutile also increased as the applied potential increased. The anatase and rutile phases of TiO 2 can be controlled by applied voltage for enhanced biocompatibility. [ABSTRACT FROM AUTHOR]

Titanium-niobium-zirconium (TiNbZr) alloys represent a promising class of newly developed titanium-based biomaterials, engineered to exhibit superior properties for biomedical applications. This study investigates the influence of hydroxylated multi-walled carbon nanotubes (MWCNTs) on the surface properties of hydroxyapatite coatings prepared by the plasma electrolytic oxidation (PEO) method for implant applications. The optimal concentration of MWCNTs in the PEO coating was determined based on the superior surface, electrochemical, and biological properties obtained. The incorporation of MWCNTs led to an enhancement in surface roughness from R a 0.06 ± 0.02 to R a 0.618 ± 0.03 µm, improved wettability with a decrease in contact angle from 63.03° ± 1.1–28.29° ± 0.07, and a reduction in elastic modulus from 77.20 ± 2.26 GPa to 54.50 ± 2.22 GPa. Furthermore, electrochemical corrosion resistance analysis revealed an increase in inner passivation resistance up to 2.24 × 10 ×7 Ω.cm2 with the addition of MWCNTs. Antibacterial activity analysis demonstrated that the optimal concentration of MWCNTs resulted in a 3.1-fold and 2.7-fold reduction in E. coli and S. aureus bacteria, respectively, compared to uncoated samples. Cell viability against MC3T3-E1 cells showed a 25 % higher viability with MWCNTs than uncoated substrates. [Display omitted] • MWCNT/HA composite coatings on TiNbZr substrate using the plasma electrolytic oxidation were researched. • TiNbZr exhibits improved favourable elastic modulus, making it a suitable candidate for dental implant applications. • MWCNT/HA composite coatings demonstrate enhanced wettability and corrosion resistance. • MWCNT/HA composite coatings exhibit enhanced biocompatibility and antibacterial activity. [ABSTRACT FROM AUTHOR]

Silicon-substituted hydroxyapatite coatings on Ti–30Nb–xTa alloys, prepared using a cyclic electrochemical deposition method, have been investigated using a variety of surface analytical experimental methods. The silicon-substituted hydroxyapatite (Si-HA) coatings were prepared by electrolytic deposition in electrolytes containing Ca 2 + , PO 4 3− and SiO 3 2− ions. The deposited layers were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and a wettability test. Phase transformation from (α″ + β) to largely β occurred with increasing Ta content in the Ti –30Nb–xTa alloys, yielding larger grain size. The morphology of the Si-HA coatings was changed by increasing the number of deposition cycles, with the initial plate-like structures changing to mixed rod-like and plate-like shapes, and finally to a rod-like structure. From the ATR-FTIR spectra, Si existed in the form of SiO 4 4− groups in Si-HA coating layer. The lowest aqueous contact angles and best wettability were found for the Si-HA coatings prepared with 30 deposition cycles. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of hydroxyapatite (HA) and titanium nitride (TiN) multi-layer coatings on Ti–Nb–Zr alloys was investigated by a variety of surface analytical methods. The HA/TiN layers were deposited using a magnetron sputtering system. The HA target was made of human tooth-ash sintered at 1300 °C for 1 h and had an average Ca/P ratio of 1.9. From X-ray diffraction patterns, the Ti–29Nb–5Zr alloy was composed entirely of equiaxed β-phase exhibiting the principal (110) reflection, and the coating exhibited the (111) and (200) reflections for TiN and the (112) and (202) reflections for HA. At the coating surface the HA films consisted of granular particles, and the surface roughness was 4.22 nm. The thickness of the coating layers increased in the order of HA/TiN (lowest), TiN, and HA (highest). Potentiodynamic polarization measurements revealed that the corrosion current density was the lowest, and the corrosion potential and polarization resistance the highest, when the Ti–29Nb–5Zr surface was covered by the HA/TiN film, compared to solely HA or TiN films. [ABSTRACT FROM AUTHOR]

The surface characteristics of hydroxyapatite coatings on nanotubular Ti–25Ta–xZr alloys prepared by electrochemical deposition for dental implants have been investigated using various methods. The Ti–25Ta–xZr alloys were prepared by an arc melting furnace, homogenized for 12 h at 1000 °C in an argon atmosphere, and then water-quenched. Nanotubular structures were formed by an electrochemical method in 1 M H 3 PO 4 electrolytes containing 0.8 wt.% NaF. Electrochemical deposition was carried out using a cyclic voltammetry method over a potential range of − 1.5 V to 0 V at 80 °C in a 5 mM Ca(NO 3 ) 2 + 3 mM NH 4 H 2 PO 4 solution. Surface characteristics were observed by optical microscopy, X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, contact angle goniometer, and image analyzer software. Microstructures of the Ti–25Ta–xZr alloys changed from α″ phase to β phase, and the phases changed in morphology from a needle-like to an equiaxed structure with increasing Zr content. The arrangement of nanotubes changed from an irregular distribution to a high level of ordering surrounded by smaller tubes, and the occupied percentage of pore wall surface decreased from 28% to 23%, as the Zr content increased. HA precipitates also changed in morphology from a plate or leaf-like shape to a needle or flower-like shape as the Zr content increased. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we investigated the surface characteristics of hydroxyapatite (HA)-coated layers prepared by electron-beam physical vapor deposition (EB-PVD) on nanotubular Ti–35Ta–xHf alloys (x=3, 7, and 15wt.%). Ti–35Ta–xHf alloys were first prepared by arc melting. Formation of a nanotube structure on these alloys was achieved by an electrochemical method in 1M H3PO4 +0.8wt.% NaF electrolytes. The HA coatings were then deposited on the nanotubular surface by an EB-PVD method. The surface characteristics were analyzed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD). The electrochemical behavior was examined using a potentiodynamic polarization test in 0.9% NaCl solution. The Ti–35Ta–xHf alloys had an equiaxed grain structure with α″+β phases, and the α″ phase disappeared with increases in Hf content. The Ti–35Ta–15Hf alloy showed higher β-phase peak intensity in the XRD patterns than that for the lower Hf-content alloys. A highly ordered nanotubular oxide layer was formed on the Ti–35Ta–15Hf alloy, and the tube length depended on Hf content. The HA coating surface formed at traces of the nanotubular titanium oxide layer and completely covered the tips of the nanotubes with a cluster shape. From the potentiodynamic polarization tests, the incorporation of Hf element and formation of the nanotubular structure were the main factors for achieving lower current density. In particular, the surface of the HA coating on the nanotubular structure exhibited higher corrosion resistance than that of the nanotubular titanium oxide structure without an HA coating. [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]

• Number of pores increased in the plasma electrolyte oxidation (PEO) as sr ions increased. • The pore size decreased in the PEO process as Sr concentration increased. • In the case of Si and Sr addition to electrolyte, corrosion potential was apparently increased. • Polarization resistances of PEO-treated Sr and Sr/Si specimens showed the higher compared to bulk. The purpose of this study is to investigate the electrochemical characteristics of Sr/Si-doped hydroxyapatite coating on the Ti-6Al-4V alloy surface via plasma electrolytic oxidation(PEO). Ti-6Al-4V alloy of extra low interstitial grade disk was used as the anode and the carbon rod was used as the cathode. PEO treatment was carried out using pulsed DC power at 280 V for 3 min. The electrolyte used for PEO was prepared by mixing Ca(CH 3 COO) 2 •H 2 O, C 3 H 7 NaCaO 6 P, Sr(CH 3 COO) 2 •0.5H 2 O, and Na 2 SiO 3 •9H 2 O. The potentiodynamic polarization test were performed by potentiostat in a 0.9% NaCl solution at 36.5 ± 1°C. Electrochemical impedance tests were carried out using potentiostat at the open circuit potential in a 0.9% NaCl solution at 36.5 ± 1°C. The PEO-treated surface and corrosion morphology were investigated by field mission scanning microscopy and energy dispersive X-ray spectroscopy. The number of pores increase and average size of the pores decreased as Sr increase, and area occupied by pore was decreased. In the case of Si and Sr addition to electrolyte, corrosion potential was apparently increased compared to specimen of Sr addition to electrolyte. Polarization resistances of PEO-treated Sr and Sr/Si specimens showed the higher than those of Bulk and CaP specimens from data of electrochemical impedance test. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate hydroxyapatite coatings on micropore-formed titanium alloy, utilizing an electrochemical deposition method. A commercially pure titanium surface was used as a substrate for calcium phosphate (CaP) deposition on micropores formed after anodization. Prepared surfaces were anodized in 1M H3PO4 solution, and CaP deposition was performed with a potentiostat at cathodic potential in an electrolyte containing 0.042M Ca(NO3)2 and 0.025M NH4H2PO4. Micropores acted as growth sites for nanophase CaP crystals. Flake-like CaP and needle-like CaP were observed at 25°C and 85°C, respectively. If the specimen was not heat-treated, octacalcium phosphate and hydroxyapatite were observed, whereas slight CaP decomposition to tricalcium phosphate occurred with heat treatment at 700°C. The phenomena involved in CaP deposition were affected by the electrolyte temperature for both morphology and nucleation site. [ABSTRACT FROM AUTHOR]