Hydroxyapatite coating on the Ti-35Nb-xZr alloy by electron beam-physical vapor deposition

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 3 wt.% to 10 wt.% 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 1 h. 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 150 nm 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.     

Nanotubular surface and morphology of Ti-binary and Ti-ternary alloys for biocompatibility

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 40 wt.%) and ternary Ti-30Ta-xNb (x = 3, 7 and 15 wt.%) alloys were prepared by using the high-purity sponges; Ti, Ta and Zr spheres. The nanotube on the alloy surface was formed in 1.0 M H₃PO₄ with small additions of NaF (0.5 and 0.8 wt.%), 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 40 wt.%, the diameter of the nanotubes in Ti-xZr and Ti-30Ta-xZr alloy decreased from 200 nm to 50 nm. The nanotubular Ti-30Ta-15Zr alloy surface with a diameter of 50 nm provided a good osseointegration; cell proliferation, migration and differentiation.     

Electrochemical oxide nanotube formation on the Ti-35Ta-xHf alloys for dental materials

In this study, we investigated the electrochemical oxide nanotube formation on the Ti-35Ta-xHf alloys for dental materials. The Ti-35Ta-xHf alloys contained from 3 wt.% to 15 wt.% Hf were manufactured by arc melting furnace. The nanotube oxide layers were formed on Ti-35Ta-xHf alloy by anodic oxidation method in 1 M H3PO4 electrolytes containing 0.5 wt.% NaF and 0.8 wt.% NaF at room temperature. The surface characteristics of Ti-35Ta-xHf alloy and nanotube morphology were determined by FE-SEM, STEM, and XRD. The nano-porous surface of Ti-35Ta-xHf alloys showed in 0.5 wt% NaF solution and nanotubular surface showed in 0.8 wt% NaF solution, respectively. The highly ordered nanotube layer without regular knots was formed on the Ti-35Ta-15Hf alloy in the 0.5 wt% NaF solution compared to on Ti-35Ta-3Hf and Ti-35Ta-7Hf alloys in 0.8 wt% NaF solution. Also, the nanotube length of Ti-35Ta-xHf alloys increased as Hf content increased.     

Surface characteristics of hydroxyapatite/titanium composite layer on the Ti-35Ta-xZr surface by RF and DC sputtering

The purpose of this study was to investigate the surface characteristics of hydroxyapatite (HA)/titanium (Ti) composite layer on the Ti-35Ta-xZr alloy surface by radio frequency (RF) and direct current (DC) sputtering for dental application. The magnetron sputtered deposition for the HA was performed in the RF mode and for the Ti in the DC mode. Microstructures of the alloys were examined by optical microscopy (OM) and x-ray diffractometer (XRD). Surface characteristics of coated film was investigated by field-emission scanning electron microscope (FE-SEM) equipped with an energy dispersive x-ray spectrometer (EDS), and XRD. Microstructures of the Ti-35Ta-xZr alloys were changed from α″ phase to β phase, and changed from a needle-like structure to an equiaxed structure with increasing Zr content. From the results of polarization behavior in the Ti-35Ta-15Zr alloy, HA/Ti composite layer showed the good corrosion resistance compared to Ti single layer. The results of alternating current (AC) impedance test indicated that the presence of ha coating acted as a stable barrier in increasing the corrosion resistance.     

Nanostructured surface changes of Ti-35Ta-xZr alloys with changes in anodization factors

The purpose of this study was to investigate the changes of the nanostructured surface of Ti-35Ta-xZr alloys for dental application resulting from changes in anodization factors. TiO₂ nanotubes were formed on Ti-35Ta-xZr alloys by anodization in H₃PO₄-containing NaF solutions. Anodization was carried out using a scanning potentiostat. Microstructures of the alloys were examined by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). Microstructures of the Ti-35Ta-xZr alloys were changed from α" phase to β phase, and morphologies changed from a needle-like to an equiaxed structure, with increasing Zr content. As the Zr content increased from 3 to 7 to 15 wt.%, the average thickness of the TiO₂ nanotubes increased from 4.5 μm to 6.1 μm to 9.0 μm. When the anodizing potential was increased from 3 V to 10 V, the thickness of the nanotube layers increased from about 0.5 μm to 9.5 μm. As the anodization time increased from 30 min to 180 min at 10 V, the nanotube thickness increased from 4 μm to 9.5 μm. The amorphous oxide phase in the nanotubes transformed to anatase and rutile phases of TiO₂ by heat treatment above 300 °C.     

Effects of molybdenum content on the structure and mechanical properties of as-cast Ti-10Zr-based alloys for biomedical applications

The effects of molybdenum on the structure and mechanical properties of a Ti-10Zr-based system were studied with an emphasis on improving the strength/modulus ratio. Commercially pure titanium (c.p. Ti) was used as a control. As-cast Ti-10Zr and a series of Ti-10Zr-xMo (x = 1, 3, 5, 7.5, 10, 12.5, 15, 17.5 and 20 wt.%) alloys prepared using a commercial arc-melting vacuum pressure casting system were investigated. X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer. Three-point bending tests were performed to evaluate the mechanical properties of all specimens. The experimental results indicated that these alloys had different structures and mechanical properties when various amounts of Mo were added. The as-cast Ti-10Zr has a hexagonal α′ phase, and when 1 wt.% Mo was introduced into the Ti-10Zr alloy, the structure remained essentially unchanged. However, with 3 or 5 wt.%, the martensitic α″ structure was found. When increased to 7.5 wt.% or greater, retention of the metastable β phase began. The ω phase was observed only in the Ti-10Zr-7.5Mo alloy. Among all Ti-10Zr-xMo alloys, the α″-phase Ti-10Zr-5Mo alloy had the lowest elastic modulus. It is noteworthy that all the Ti-10Zr and Ti-10Zr-xMo alloys had good ductility. In addition, the Ti-10Zr-5Mo and Ti-10Zr-12.5Mo alloys exhibited higher bending strength/modulus ratios at 20.1 and 20.4, respectively. Furthermore, the elastically recoverable angles of these two alloys (26.4° and 24.6°, respectively) were much greater than those of c.p. Ti (2.7°). Given the importance of these properties for implant materials, the low modulus, excellent elastic recovery capability and high strength/modulus ratio of α″ phase Ti-10Zr-5Mo and β phase Ti-10Zr-12.5Mo alloys appear to make them promising candidates.     

Nanotubular oxide surface and layer formed on the Ti-35Ta-xZr alloys for biomaterials

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.     

Nanostructured thin film formation on femtosecond laser-textured Ti-35Nb-xZr alloy for biomedical applications

The aim of this study was to investigate the nanostructured thin film formation on femtosecond (FS) laser-textured Ti-35Nb-xZr alloy for biomedical applications. The initial surface roughening treatment involved irradiation with the FS laser in ambient air. After FS laser texturing, nanotubes were formed on the alloy surface using a potentiostat and a 1 M H₃PO₄ solution containing 0.8 wt.% NaF with an applied cell voltage of 10 V for 2 h. The surface phenomena were investigated by FE-SEM, EDS, XRD, XPS and a cell proliferation test. It was found that nanostructured Ti-35Nb-xZr alloys after FS laser texturing had a hybrid surface topography with micro and nano scale structures, which should provide very effective osseointegration.     

Snoek-type damping behavior of surface oxidation-treated Ti-Mo alloys

The Snoek relaxation damping behavior of surface oxidation-treated Ti-15 wt% Mo and Ti-40 wt% Mo alloys was investigated in this study. When compared to the untreated samples, both alloys exhibited higher damping capacities, higher peak temperatures, and broader peaks after the surface oxidation treatment. The broadening of peak was reflected by a lower activation energy obtained through fitting the peak than that obtained form frequency shift of the peak. The electron backscatter diffraction (EBSD) and hardness measurements were used to determine the composition of the dual phase zones and the hardness of each type of treated alloy, respectively. The oxygen distributions in both types of treated alloys were developed based on a diffusion model, and the thicknesses of the apparent oxygen solution zones (AOSZs) were determined to be 120 μm and 210 μm in the Ti-15 wt% Mo and Ti-40 wt% Mo alloys, respectively. The diffusion constants at a high oxidation temperature and at a low damping temperature were obtained for both alloys. The dependence of the damping capacity on the oxygen content in the Ti-40 wt% Mo alloys was much lower than that in the Ti-15 wt% Mo alloys. The contribution to the damping capacity from the AOSZ to the whole sample was estimated based on the law of mixtures. Estimating the contribution to the damping capacity from AOSZ is useful for future applications.     

The role of microstructure in the mechanical behaviour of Ti-1.6 wt.%Fe alloys containing O and N

The effects of small changes to the heat treatment temperature within the (α + β) phase field on the room temperature properties of a Ti-1.6 wt.%Fe-0.56 wt.%O-0.04 wt.%N alloy are described. To identify contributions from the individual alloying elements the binary Ti-1.6 wt.%Fe and ternary Ti-1.6 wt.%Fe-0.6 wt.%O and Ti-1.6 wt.%Fe-0.04 wt.%N alloys were also investigated. It was found that the interstitial elements affected the degree of disorder in the ω_ath phase, and that the magnitude of this disordering was not merely consistent with changes in Fe concentration. The strength and ductility of the alloys free of additional nitrogen were independent of annealing temperature, whereas the alloys containing nitrogen showed a marked dependency on the temperature. Alloys containing nitrogen displayed a prismatic rather than basal texture after processing.     

Fabrication of ZnO submicrorod films with water repellency by surface etching and hydrophobic modification

Superhydrophobic ZnO submicrorod films have been fabricated on zinc sheets through an H₂O₂-assisted surface etching process and subsequent surface modification with a monolayer of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FDS). The crystal structure, chemical compositions, morphologies, and wettability of the resultant ZnO films were analyzed by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and water contact angle measurements. It is found that the surface of the as-prepared ZnO films on zinc substrate was hydrophobic with a water contact angle of 95 ± 2°, whereas after modification with FDS, the film exhibited superhydrophobicity and the water CA increased to 154 ± 2°. It is shown that both the higher surface roughness and the lower surface free energy play an important role in creating the superhydrophobic films.     

Corrosion properties and corrosion evolution of as-cast AZ91 alloy with rare earth yttrium

The corrosion resistance property and the corrosion evolution of as-cast AZ91 alloy with rare earth Y addition are investigated by using immersion tests, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The results show that the proper amount of Y in the alloys can improve the corrosion resistance of AZ91 alloys effectively. With the increment of Y, the corrosion rate of the modified AZ91 alloys by Y addition was markedly less than that of AZ91 alloy. The corrosion rate of AZ91 alloy with 0.3 wt.% Y was the slightest, but further addition of Y content over 0.3 wt.% make the corrosion heavier. The XPS analysis suggests that the compound film of AZ91 alloy with 0.3 wt.% Y is mainly composed of Mg(OH)₂ and MgCO₃ without any Al(OH)₃ and Al₂O₃, in addition, Y₂O₃ phase is found in the compound film of AZ91 alloy with 0.3 wt.% Y, which benefits to stabilize the surface film.     

Plasma surface interaction in PACVD and PVD systems during TiAlBN nanocomposite hard thin films deposition

In a PACVD system, titanium alloys were exposed to inductive radio-frequency (RF) plasmas of H₂ + N₂ and Ar + BCl₃+H₂ + N₂ gas mixtures for their nitriding and boron nitride respectively. Hard nanocomposite thin films of TiAlN and TiAlBN were formed on Ti-6Al-4V alloys in an inductive RF plasma of Ar + H₂ + N₂ and Ar + 3.5 vol.% of BCl₃ + H₂ + N₂, respectively. The substrates were grounded, i.e., self-biased, during plasma thin film formation for 30 min each. TiAlBN was deposited by sputtering in a reactive PVD system. A quadrupole mass spectrometer (QMS) sampled the plasma at a constant distance of 0.5 cm from the sample surface in real time. The mass species (m/e) at 0.5 cm were recorded during the deposition process. To separate the particles reaching the substrate surface from those leaving it, the nanocomposite thin films coated samples of Ti alloys were introduced in an RF plasma of Ar + H₂ mixture without the presence of N₂ and BCl₃ and negatively biased up to V_b = − 350 V. The QMS at 0.5 cm measures the etched and sputtered species from the surface of the coated samples. Comparing the QMS results between the grounded samples with the monomers in the RF plasma and the negatively biased voltage samples without monomers in the Ar + H₂ plasma the net plasma surface interactions (PSI) were evaluated. The behavior of the coating process of nanocomposite thin films of TiAlN and TiAlBN on the Ti alloy samples is strongly dependent on the plasma surface phenomena.     

Structural and mechanical properties of titanium oxide thin films for biomedical application

Titanium oxide thin films were deposited by radiofrequency reactive sputtering in Ar-O₂ atmosphere on silicon (100) wafers and titanium alloy plates (Ti-6Al-4V). Thin films structural characterization was carried out by grazing incidence X-ray diffraction, atomic force microscopy, scanning and transmission electron microscopies. Chemical composition was checked by X-ray wavelength dispersive spectroscopy. Mechanical assessment was achieved by nano-indentation and nano-scratch measurements. The films deposited on silicon substrates are over-stoechiometric in oxygen, with an oxygen to titanium ratio of about 2.2. The growth of anatase and rutile phases was promoted by ranging the total and oxygen partial pressures between 0.17-1.47 Pa and 35-85%. The growth rate of films, determined by grazing incidence X-ray reflectivity, was ranging from 35 to 55 nm/h. The rutile single-phased films possess a hardness of about 2.5 times higher and a lower friction coefficient than the anatase films. The films which contain anatase possess a high surface root-mean-square roughness and a reduced elastic modulus of around 120 GPa close to reduced elastic moduli of hydroxyapatite bioceramic and titanium alloy. So the anatase film could be the best candidate as a titanium oxide intermediate layer between hydroxyapatite and titanium alloy in the field of biomedical implants.     

Structural and optical properties of nanocrystalline CdSe and Al:CdSe thin films for photoelectrochemical application

Nanocrystalline CdSe and Al:CdSe semiconductor thin films have been successfully synthesized onto amorphous and FTO glass substrates by spray pyrolysis technique. Aqueous solutions containing precursors of Cd and Se have been used to obtain good quality films. The optimized films have been characterized for their structural, morphological, wettability and optical properties. X-ray diffraction (XRD) studies show that the films are polycrystalline in nature with hexagonal crystal structure. Scanning electron microscopy (SEM) studies show that the film surface is smooth, uniform and compact in nature. Water wettability study reveals that the films are hydrophilic behavior. The formation of CdSe and Al:CdSe thin film were confirmed with the help of FTIR spectroscopy. UV–vis spectrophotometric measurement showed a direct allowed band gap lying in the range 1.673–1.87 eV. Output characteristics were studied by using cell configuration n- CdSe/Al:CdSe |1 M (NaOH + Na₂ + S)|C. An efficient solar cell having a power conversion efficiency of 0.38% at illumination 25 mW cm⁻² was fabricated.     

Synthesis and characterization of carbon/silica superhydrophobic multi-layer films

C/SiO₂ multi-layer films (3-layer films and 5-layer films) were obtained by sol-gel method and physical deposition on glass plates, and then heated at 500 °C for 1 h under a nitrogen atmosphere. The mechanical adhesive force with the substrate of the multi-layer films was sharply enhanced compared to the as-deposited amorphous carbon film. An absorption layer was formed on heat treated C/SiO₂ multi-layer films by modification of the surface with trimethylchlorosilane, and the wettability of the films changed from hydrophilic to super-hydrophobic. The structures of the physically deposited carbon and the multi-layer films were analyzed by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The experimental results showed that the 5-layer films had a concentric ring structure that caused the film to be superhydrophobic.     

Effect of V content on the microstructure and mechanical properties of Mo2FeB2 based cermets

Four series of cermets with V content between 0 and 7.5 wt.% in 2.5 wt.% increments were studied by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The transverse rupture strength (TRS), hardness (HRA) and fracture toughness (K_IC) were also measured. It was found that the grain size was affected by the V content. The cermets with 2.5 wt.% V addition exhibited the smallest grain size. An increasing V content decreased the wettability of the binder on the Mo₂FeB₂ hard phase, and accordingly resulted in the increase of porosity and aggregation of ceramic grains. EDS results showed that V addition occurred primarily in the hard phase, with a little amount in the Fe alloy binder. In addition, the content of Mo element in the binder decreased with increasing V content. The cermets with 2.5 wt.% V addition showed the highest TRS, hardness and fracture toughness of 2350 MPa, HRA 90.6 and 15.1 MPa m^1/2, respectively.     

Influence of annealing temperature on the structural, mechanical and wetting property of TiO2 films deposited by RF magnetron sputtering

TiO₂ films have been deposited on silicon substrates by radio frequency magnetron sputtering of a pure Ti target in Ar/O₂ plasma. The TiO₂ films deposited at room temperature were annealed for 1 h at different temperatures ranging from 400 °C to 800 °C. The structural, morphological, mechanical properties and the wetting behavior of the as deposited and annealed films were obtained using Raman spectroscopy, atomic force microscopy, transmission electron microscopy, nanoindentation and water contact angle (CA) measurements. The as deposited films were amorphous, and the Raman results showed that anatase phase crystallization was initiated at annealing temperature close to 400 °C. The film annealed at 400 °C showed higher hardness than the film annealed at 600 °C. In addition, the wettability of film surface was enhanced with an increase in annealing temperature from 400 °C to 800 °C, as revealed by a decrease in water CA from 87° to 50°. Moreover, the water CA of the films obtained before and after UV light irradiation revealed that the annealed films remained more hydrophilic than the as deposited film after irradiation.     

Epitaxial growth and thermoelectric properties of TiNiSn and Zr0.5Hf0.5NiSn thin films

Due to their exceptional thermoelectric properties Half-Heusler alloys like MNiSn (M = Ti,Zr,Hf) have moved into focus. The growth of single crystalline thin film TiNiSn and Zr_0.5Hf_0.5NiSn by dc magnetron sputtering is reported. Seebeck and resistivity measurements were performed and their dependence on epitaxial quality is shown. Seebeck coefficient, specific resistivity and power factor for Zr_0.5Hf_0.5NiSn at room temperature were measured to be 63 μV K^− 1, 14.1 μΩ m and 0.28 mW K^− 2 m^− 1, respectively. Multilayers of TiNiSn and Zr_0.5Hf_0.5NiSn are promising candidates to increase the thermoelectric figure-of-merit by decreasing thermal conductivity perpendicular to the interfaces. The epitaxial growth of multilayers containing TiNiSn and Zr_0.5Hf_0.5NiSn is demonstrated by measuring satellite peaks in the X-ray diffraction pattern originating from the additional symmetry perpendicular to the film surface.     

Electrolytic deposition of hydroxyapatite coating on thermal treated Ti-40Zr

In this study, hydroxyapatite (HA) was coated on both thermal treated and untreated Ti-40Zr substrates by means of electrolytic deposition. It was predicted that the HA layer would increase the bioactivity and osteoconductivity of the Ti-40Zr substrate, and a thermal treatment would improve the bonding strength between the HA layer and Ti-40Zr substrate, and prevent the corrosion of the Ti-40Zr substrate. First, the Ti-40Zr samples were annealed at various temperatures (200, 300, 400, 500 and 600°C respectively). After annealing, samples were immersed in a Ca(NO₃)₂ · 4H₂O and (NH₄)₃PO₄ · 3H₂O solution for the electrolytic deposition of the HA coating. Various analyses of the coating were conducted, including surface morphology, phase structure, corrosion resistance, biocompatibility, and bond strength between HA and Ti-40Zr. Experimental results indicated that the bonding strength of the HA coating on the thermal treated Ti-40Zr was markedly improved when compared to that of the HA coating on an untreated Ti-40Zr alloy. The corrosion resistance of Ti-40Zr was also improved by the use of the thermal treatment, as shown by a potentiodynamic polarization test. Finally, osteoblast-like cells cultured on the HA coating surface were found to have proliferated on all samples.