Titanium Beta Research Articles

Effect of Molybdenum on the Mechanical and Corrosion Properties of Ti-xMo-2Fe Beta Alloys

Titanium alloys are currently used in offshore industries. The titanium alloys used in offshore plants need to have excellent corrosion resistance and mechanical properties because offshore plants are exposed to harsh corrosive environments. At this time, the Ti-6Al-4V ELI alloy is mainly used in offshore plants because it has excellent mechanical properties and corrosion resistance. However, Ti-6Al-4V ELI alloy has the disadvantage of poor formability. To improve this, studies on metastable beta-Titanium alloys with a BCC structure are being actively conducted. In this study, a metastable beta-titanium alloy was fabricated using Mo, which is inexpensive and improves corrosion resistance, and Fe, which improves strength, among the titanium beta stabilizer elements. After the Ti-6Al-4V ELI and Ti-xMo-2Fe alloys solution treatments, electrochemical corrosion experiments were conducted to analyze corrosion characteristics, and mechanical properties were also analyzed through compression tests at room temperature and Vickers hardness measurement. Corrosion properties and the mechanical properties of Ti-xMo-2Fe alloy were considered in connect experiments such as microstructure analysis and hardness measurement. It was confirmed that the corrosion resistance of the Ti-xMo-2Fe alloy was better than that of the Ti-6Al-4V ELI alloy, and it was confirmed that the compressive strength and elongation rate of Ti-xMo-2Fe with its BCC structure get higher than Ti-6Al-4V ELI alloy.

The Use of Electrochemical Methods to Determine the Effect of Nitrides of Alloying Elements on the Electrochemical Properties of Titanium β-Alloys.

Titanium beta alloys represent the new generation of materials for the manufacturing of joint implants. Their Young's modulus is lower and thus closer to the bone tissue compared to commonly used alloys. The surface tribological properties of these materials should be improved by ion implantation. The influence of this surface treatment on corrosion behaviour is unknown. The surface of Ti-36Nb-6Ta, Ti-36Nb-4Zr, and Ti-39Nb titanium β-alloys was modified using nitrogen ion implantation. X-ray photoelectron spectroscopy was used for surface analysis, which showed the presence of titanium, niobium, and tantalum nitrides in the treated samples and the elimination of less stable oxides. Electrochemical methods, electrochemical impedance spectra, polarisation resistance, and Mott-Schottky plot were measured in a physiological saline solution. The results of the measurements showed that ion implantation does not have a significant negative effect on the corrosion behaviour of the material. The best results of the alloys investigated were achieved by the Ti-36Nb-6Ta alloy. The combination of niobium and tantalum nitrides had a positive effect on the corrosion resistance of this alloy. After surface treatment, the polarization resistance of this alloy increased, 2.3 × 106 Ω·cm2, demonstrating higher corrosion resistance of the alloy. These results were also supported by the results of electrochemical impedance spectroscopy.

Nanostructured titanium alloy surfaces for enhanced osteoblast response: A combination of morphology and chemistry

This study is part of a new trend in the metallic biomaterials field that searches to use the titanium beta alloys with recognized bulk and surface properties for better biological response. Ti15Mo alloy (wt%) had it surface modified by TiO2 nanotubes growth using the anodic oxidation method and grafted with poly(sodium styrene sulfonate) (PNaSS). The motivation behind the combination of these techniques was to promote a surface, which enables better osteointegration associated with antimicrobial behavior. Surfaces were characterized and subjected to cell culture assays and bacterial colonization to evaluate their in vitro response. The results showed that the surfaces were completely covered with TiO2 nanotubes, which was successfully grafted with PNaSS. Compared with untreated Ti 15Mo surfaces, PNaSS grafted nanotubes surfaces showed better osteoblast cell response in terms of cell attachment and mineralization and weaker bacterial adhesion and colonization. The results suggest that the final product of the combine treatment – nanotube plus PNaSS grafting - represents a promising option to improve commercial metallic implants.

Corrosion behaviour of the titanium beta alloy nanotubular surface in the presence of fluoride ions

Abstract The titanium bioactivity could be increased by surface nanostructuring. Titanium alloys are using for dental implants manufacturing. It represents a specific problem because of using of the dental treatments with high concentration of fluoride ions and with acidic pH. The corrosion resistance of nanostructured surface of titanium beta alloy in environments with fluoride ions was examined by common electrochemical technique. The electrochemical impedance measurement showed high corrosion resistance in physiological solution. The fluoride ions have expected negative influence on corrosion behaviour of the layer. The nanotube bottom was preferentially attacked which resulted in layer undercoroding and its detachment.

Single block 3D numerical model for linear friction welding of titanium alloy

ABSTRACTA two-stage approach for the simulation of Linear Friction Welding is presented. The proposed model, developed using the commercial simulation package DEFORM, is 3D Lagrangian, thermo-mechanically coupled. The first phase of the process was modelled with two distinct workpieces, while the remaining phases were simulated using a single-block model. The Piwnik–Plata criterion was set up and used to determine the shifting from the dual object to the single-block model. The model, validated against experimental temperature measurements, is able to predict the main field variables distributions with varying process parameters. Titanium alpha and beta phases evolution during the whole process has been predicted and the obtained results have been correlated to the experimentally measured micro-mechanical properties of the joints.

Structure evolution analysis in ultrafine-grained Zr and Nb-based beta titanium alloys

Titanium beta type alloys with an ultrafine grain microstructure are interesting biomaterials that exhibit an excellent mechanical, physicochemical and biological properties. This study aimed to develop a new Ti14Zr16Nb and Ti23Zr25Nb (at. %) alloys. These materials were prepared by the combination of mechanical alloying and powder metallurgy approach with cold powder compaction and sintering or interchangeably hot pressing. The details of the processing method were presented for structure evolution analysis. The samples were characterized by an X-ray diffraction method, scanning electron microscopy observation, chemical composition determination, sinters porosity measurements and finally mechanical properties evaluation. The microscopic studies confirmed the ultrafine grain structure of the sinters. The mechanically alloyed Ti23Zr25Nb material upon sintering at 600 °C for 10 min led to the formation of the single β type phase structure. The present study has demonstrated that ultrafine structure for Ti14Zr16Nb and Ti23Zr25Nb systems proposed for medical implant applications can be fabricated by the application of hot pressing of mechanically alloyed powders at the temperature below α→β transus (600 °C).

On the increasing of adhesive strength of nanotube layers on beta titanium alloys for medical applications

The nanostructuring of titanium and its alloys surfaces is used inter alia for increasing the medical implants osseointegration. Many papers about this topic were published. However, in most cases there were no informations about nanostructures adhesion to the surface, which is crucial from the application point of view. The aim of this study was to prepare nanostructures on titanium beta alloy and optimized its adhesion to the alloy surface. Nanotubes were formed by anodic polarization in electrolyte containing fluoride ions. The composition of the nanotubes was described by X-ray photoelectron spectroscopy. Nanostructures adhesion was tested by pull-of method. The nanotubes on the Ti–36Nb–6Ta beta alloy surface were prepared by anodization. The nanostructures properties were modified by electrochemical process parameters. The adhesion of the nanotubes prepared in this work was satisfactory for implantological applications.

Kinetic Study and Optimization of Oxidative Desulfurization of Benzothiophene Using Mesoporous Titanium Silicate-1 Catalyst

The oxidative desulfurization (ODS) of benzothiophene (BT) in isooctane as a model fuel with 30% aqueous H2O2 was studied using three different titanium silicate (TS) zeolites, synthesized mesoporous TS-1, synthesized mesoporous titanium beta, and commercial TS-1 catalyst, which were found to give 85.6, 45.74, and 25.31% conversions, respectively. Therefore, mesoporous TS-1 was selected as the catalyst for ODS of BT. Reaction time, temperature, catalyst loading, and molar ratio of H2O2:S were selected as the pertinent parameters for the optimization of conversion based on the Box–Behnken design. The predicted maximum conversion was observed to be 89.9% at a temperature of 60 °C, catalyst loading of 0.064 g, and mole ratio of BT and H2O2 of 0.209. An empirical kinetic model was used to fit the rate data. The activation energy was found to be 25.20 kJ/mol.

A controlled post-synthesis route to well-defined and active titanium Beta epoxidation catalysts

This paper describes the successful indirect synthesis of a titanium Beta zeolite. The post-synthesis modification, consisting of separate dealumination and titanation steps, is extensively studied by X-ray diffraction, Fourier-transformed infrared (FT-IR), X-ray photoelectron spectroscopy, diffuse reflectance UV–Vis and Raman spectroscopy. Dealumination degrees up to 90% could be obtained by using oxalic acid as well as nitric acid without any loss in crystallinity or micropore volume. FT-IR shows the formation of silanol nests upon removal of aluminum from the zeolite framework. Subsequently, these silanol nests react with titanium(IV) chloride in the titanation step, resulting in tetrahedral titanium sites. The post-synthesis procedure described allows the preparation of titanium zeolites that are free from TiO 2. The results of the titanation experiments suggest that the vacant sites are first filled with titanium, resulting in tetrahedral, isolated titanium sites, before the formation of TiO 2 starts to occur. As such, the titanium loading can be tuned to about 2 wt.% titanium and, at the same time, the formation of TiO 2 species is prevented. The titanium Beta materials obtained are active and truly heterogeneous epoxidation catalysts. Both with tert-butyl hydroperoxide (under dry conditions) and with aqueous H 2O 2, they effectively catalyze the epoxidation of alkenes under mild conditions. It is demonstrated that TiO 2-free catalysts are highly preferable, since traces of TiO 2 present on the titanium zeolite impair the catalyst performance. In the epoxidation of 1-octene, the Ti–Beta catalysts prepared via the controlled post-synthesis route can easily compete with TS-1 under the same conditions.

Synthesis and characterization of aluminum-free zeolite titanium beta using di(cyclohexylmethyl)dimethylammonium as a new and selective template

The aluminum-free titanium silicate analogue of zeolite beta was synthesized using di(cyclohexylmethyl)dimethylammonium as the template. The Ti-beta zeolite was characterized using powder XRD, UV–vis spectroscopy, FTIR, X-ray unit cell expansion, TEM, SEM, EDX, nitrogen adsorption and SAXS. The influence of the external surface on the catalytic activity was determined by catalytic epoxidation experiments using surface sensitive probe molecules. Evidence was obtained for the isolated incorporation of titanium in the zeolite lattice from X-ray unit cell expansion. The linear expansion of the unit cell volume with increasing titanium content corresponds to an average Ti–O bond length of 1.79 Å. EDX showed a homogeneous distribution of titanium over the zeolite framework and the absence of titanium-rich phases. The morphology of the crystals as determined by SEM is a pillow-shaped particle with an average diameter of 1.2 μm. Sometimes a thin amorphous layer or small particles were detected with TEM at the crystal surface. By using 3,5-di-tert-butylphenyl 1-(3-methyl 2-butenyl) ether as a selective bulky probe molecule for external surface titanium sites, it was shown that epoxidation takes place primarily at the titanium sites located at the internal surface of the zeolite.

Zeolite titanium beta as a selective catalyst in the epoxidation of bulky alkenes

The catalytic potential of aluminum-free zeolite titanium beta (Ti-beta) is demonstrated by its facile catalysis of the epoxidation of alkenes with aqueous hydrogen peroxide. The Ti-beta catalyst is compared with TS-1, Ti,Al-beta and Ti-MCM-41 in the epoxidation of 1-octene and norbornene. The advantage of the larger pore size of Ti-beta is illustrated by the facile epoxidation of norbornene in which TS-1 displayed no activity. Rate differences in the epoxidation of terminal or internal alkenes are very small for Ti-beta, indicating that the Ti-site is rather spacious. The catalytic properties of Ti-beta were further investigated in the epoxidation of bulky alkenes such as cyclohexenes, cyclic terpenes and allylic alcohols. Ti-beta was found to catalyze the epoxidation of a wide variety of alkenes with aqueous hydrogen peroxide. In the epoxidation of linear alkenes two trends were observed. The lower alkenes were epoxidized fastest and the internal alkenes were slightly faster than the alkenes with a terminal double bond. The reactivity of methylenecyclohexane is about twice that of 1-methylcyclohexene. Based on electronic effects of substituents the reverse order would be expected, which suggests that here steric effects at the titanium site can play a dominant role in determining reactivity. Pronounced electronic effects were observed to be more important in the epoxidation of allylic alcohols: more highly substituted allylic alcohols are more reactive, whereas the reactivity of the substrates bearing a terminal, unsubstituted double bound is over an order of lower magnitude.

Zeolite Titanium Beta: A Selective Catalyst for the Gas-Phase Meerwein–Ponndorf–Verley, and Oppenauer Reactions

Aluminium-free zeolite titanium beta was tested in the Meerwein–Ponndorf–Verley reduction of 4-methylcyclohexanone with various secondary and primary alcohols as hydrogen donors, using a fixed-bed continuous-flow gas-phase reactor. A high selectivity towards the thermodynamically unfavourablecis-4-methylcyclohexanol was observed, which is ascribed to transition-state selectivity in the straight channels of zeolite beta. However, in the gas-phase, the selectivity to thecis-alcohol is significantly lower than in the liquid-phase when using 2-propanol as the hydrogen donor. Based on kinetic and adsorption experiments, it is concluded that the concentration of alcohol reductant in the zeolite is an important parameter in determining selectivity. More hydrophobic alcohols give rise to an increased selectivity to thecis-alcohol product. From the sorption experiments it was concluded that this is due to a higher internal concentration of the alcohol reductant in the hydrophobic titanium beta zeolite. The observed selectivities and activities are consistent with a mechanism in which this alcohol is not only the hydrogen donor but is also required to remove thecis-alcohol product formed from the catalytic site by alcoholysis, before consecutive reactions can take place.

Zeolite Titanium Beta*1A Selective Catalyst for the Gas-Phase Meerwein–Ponndorf–Verley, and Oppenauer Reactions

Abstract Aluminium-free zeolite titanium beta was tested in the Meerwein–Ponndorf–Verley reduction of 4-methylcyclohexanone with various secondary and primary alcohols as hydrogen donors, using a fixed-bed continuous-flow gas-phase reactor. A high selectivity towards the thermodynamically unfavourablecis-4-methylcyclohexanol was observed, which is ascribed to transition-state selectivity in the straight channels of zeolite beta. However, in the gas-phase, the selectivity to thecis-alcohol is significantly lower than in the liquid-phase when using 2-propanol as the hydrogen donor. Based on kinetic and adsorption experiments, it is concluded that the concentration of alcohol reductant in the zeolite is an important parameter in determining selectivity. More hydrophobic alcohols give rise to an increased selectivity to thecis-alcohol product. From the sorption experiments it was concluded that this is due to a higher internal concentration of the alcohol reductant in the hydrophobic titanium beta zeolite. The observed selectivities and activities are consistent with a mechanism in which this alcohol is not only the hydrogen donor but is also required to remove thecis-alcohol product formed from the catalytic site by alcoholysis, before consecutive reactions can take place.

Application of zeolite titanium Beta in the rearrangement of α-pinene oxide to campholenic aldehyde

Zeolite titanium Beta is found to be an effective catalyst for the industrially relevant rearrangement of α-pinene oxide to campholenic aldehyde, giving selectivities of up to 89% in the liquid phase. In the gas phase, up to 94% selectivity is obtained at conversions above 95%, which exceeds the best values obtained with homogeneous Lewis acid catalysts. The selectivity obtained is profoundly influenced by the solvent or co‐adsorbate applied.

Zeolite titanium beta: a selective and water resistant catalyst in Meerwein-Ponndorf-Verley-Oppenauer reactions

Aluminium-free zeolite titanium beta was found to be a selective and water stable catalyst in the Meerwein-Ponndorf-Verley reduction of alkylcyclohexanones and the Oppenauer oxidation of alkylcyclohexanol. 4-t-butyl- and 4-methylcyclohexanone were reduced with > 98% selectivity to the cis-alcohol. The high stereoselectivity is explained by transition-state selectivity.

Influence of the solvent on the titanium beta catalyzed oxidation of phenylethylenes without carbon-carbon double bond cleavage

Phenylethylenes can be oxidized in methanol by hydrogen peroxide in the presence of zeolite beta containing titanium (Ti-β) to give predominantly glycol monomethyl ethers (arising from the acidcatalyzed opening up of the primary epoxide) accompanied by lower amounts of carbonyl compounds (derived from the oxidative C—C bond cleavage). These results contrast with those obtained using the same Ti-β catalyst in acetonitrile or acetone as solvent or with those previously reported using titanium silicalite, where C—C bond rupture was the main process.

New titanium beta zeolite for selective oxidation

New titanium beta zeolite for selective oxidation

Nucleation of Cavitation by Alpha Irradiation of Liquid Helium

It has been shown that the presence of an alpha particle emitter, a 1 mCi Po210 sealed source, causes a lowering of the ultrasonic cavitation noise threshold in helium II by as much as 50%, the sound field being generated by a cylindrical PZT 4 transducer resonant at 57 kHz. The lowest temperature investigated was 1.80°K. Thresholds corresponding to various specific sound-level increments were determined from graphic records. There is no discernable effect on the threshold in helium I, so that the nucleation mechanism cannot be the formation of microbubbles at hot spots as in Seitz's theory [Phys. Fluids 1, 2–13 (1968)]. Neither the presence of a 13 mCi tritiated titanium beta source nor electric fields affected the nucleation, so that ions, per se, are also ruled out as a nucleating mechanism. However, several similarities to the behavior of the threshold in the presence of a rotating shaft and bucket were observed. Evidence was obtained indicating that the cavitation noise was localized in the vicinity of the alpha source. It is concluded that the nucleation occurs on vortex filaments created by the alpha particles.