Pure Titanium Powder Research Articles

INFLUENCES OF DEPOSITION TIME ON TIO2 THIN FILMS PROPERTIES PREPARED BY CVD TECHNIQUE

Titanium dioxide (TiO2) is known as a material with exceptionally good optical, mechanical and thermal properties. An increasing interest has been devoted to the study of TiO2 because of their numerous applications in various industries. In this study, by controlling process parameters, TiO2 thin films were successfully deposited on a glass substrate using chemical vapor deposition (CVD) technique. It has been fabricated using two source materials that are 99.9 % pure titanium and graphite powder at 1000 °C annealing temperature. The deposition time were observed at 1 hour, 2 hours and 3 hours. The TiO2 thin films properties were characterized using X-Ray Diffraction (XRD), Atomic Force Microscope (AFM), Ultraviolet-Visible Spectroscopy (UV-Vis), Surface Profilometer (SP) and Current-Voltage (I-V) Measurement Tools. Based on XRD results, the intensity of mixed anatase, rutile, cotunnite type and TiO2 was highest for 3 hours deposition time. AFM images reveal the crystalline morphology with average grain size of 151.662 nm. The band gap energy obtained from UV-Vis as well as thicknesses gained from SP and resistivity acquired from Current-Voltage (I-V) Measurement of deposited TiO2 thin films were increasing with deposition time. It is vice versa for the conductivity of deposited TiO2 thin films that is declining with increasing of deposition time. It can be concluded from the experimental results that the deposition time affects the TiO2 thin films properties.

Guías y miniplacas personalizadas: un protocolo guiado para cirugía ortognática

IntroductionTechnological advances in preoperative planning and 3D printing allow custom-made biomedical devices to be synthesised using a completely digital workflow. The aim of this paper is to present and critically evaluate a new Orthognathic Positioning System (OPS) for Orthognathic Surgery. The OPS used bone-supported guides and a custom mini-plate to allow maxillary fragment positioning and fixation without the need for an inter-maxillary occlusal splint. Materials and methodsA prospective observational study was conducted on 10 cases of bimaxillary surgery using an inverse planning protocol. The guide and the custom-made mini-plate were designed using CAD-CAM software and synthesised by laser from commercially pure titanium powder. Accuracy was evaluated by overlap comparison of the virtual planning and 1-month postoperative CT scan. Operation times, complications, and overall safety profile were analysed. ResultsThe OPS was successfully applied to all cases, and was well tolerated. Operation times were reduced by avoiding inter-maxillary fixation, mini-plate bending, and obviating the need for intra-operative measurements. A mean postoperative accuracy of 1mm was obtained in 68.1% of cases. ConclusionsThe positioning systems for orthognathic surgery that involve custom made systems of osteosynthesis, can be a future option that could increase accuracy and the safety of the procedure, as well as the surgical times. We believe this novel technology is a step forward in optimising and improving the delivery of orthognathic surgery care.

Laser melting of titanium-diamond composites: Microstructure and mechanical behavior study

Titanium matrix composites (TMCs) were prepared in situ using continuous wave ytterbium doped fiber laser in order to improve the mechanical properties of titanium. In this study, 5, 10 and 15wt% diamond powders were premixed with commercially pure titanium (CP-Ti) powder and were laser melted using laser engineered net shaping (LENS™) system. The microstructure, reaction phases and mechanical behavior were investigated to understand the influences of diamond concentration. Average cross sectional hardness of the composite increased from 348 HV to 984 HV with increase in the diamond concentration from 5 to15 wt%. Similarly, the Young’s modulus of the composite, measured using nanoindentation, increased from 169 to 629GPa. Such high mechanical properties of laser melted composites envisage their potential for wear resistant and high temperature applications.

Post Processing and Biological Evaluation of the Titanium Scaffolds for Bone Tissue Engineering.

Nowadays, post-surgical or post-accidental bone loss can be substituted by custom-made scaffolds fabricated by additive manufacturing (AM) methods from metallic powders. However, the partially melted powder particles must be removed in a post-process chemical treatment. The aim of this study was to investigate the effect of the chemical polishing with various acid baths on novel scaffolds’ morphology, porosity and mechanical properties. In the first stage, Magics software (Materialise NV, Leuven, Belgium) was used to design a porous scaffolds with pore size equal to (A) 200 µm, (B) 500 µm and (C) 200 + 500 µm, and diamond cell structure. The scaffolds were fabricated from commercially pure titanium powder (CP Ti) using a SLM50 3D printing machine (Realizer GmbH, Borchen, Germany). The selective laser melting (SLM) process was optimized and the laser beam energy density in range of 91–151 J/mm3 was applied to receive 3D structures with fully dense struts. To remove not fully melted titanium particles the scaffolds were chemically polished using various HF and HF-HNO3 acid solutions. Based on scaffolds mass loss and scanning electron (SEM) observations, baths which provided most uniform surface cleaning were proposed for each porosity. The pore and strut size after chemical treatments was calculated based on the micro-computed tomography (µ-CT) and SEM images. The mechanical tests showed that the treated scaffolds had Young’s modulus close to that of compact bone. Additionally, the effect of pore size of chemically polished scaffolds on cell retention, proliferation and differentiation was studied using human mesenchymal stem cells. Small pores yielded higher cell retention within the scaffolds, which then affected their growth. This shows that in vitro cell performance can be controlled to certain extent by varying pore sizes.

The Influence of Gas-Phase Hydrogenation Parameters on the Processes of Activation, Sorption and Accumulation of Hydrogen in the Powder of Pure Titanium

The technique for hydrogenation of powder hydrogen-storage materials based on gas-phase hydrogenation method has been developed in this work. The using of developed technique allow prepare pure titanium powder samples with hydrogen concentration in range from 0.5 to 4 wt.%. It was showed, that pressure increasing from 0.5 to 2 atm at constant temperature 400 °C leads to decreasing of powder activation time from 140 to 15 s. Temperature increasing on 50 °C and more degrees leads to significant decreasing of powder activation time. Pressure increasing from 0.5 to 2 atm leads to increasing of hydrogen sorption rate and concentration in 1.27 and 1.19 times respectively. Temperature increasing from 400 to 550 °C leads to increasing of hydrogen sorption rate in 1.3 times, but decreasing of hydrogen concentration in 1.45 times, which associated with decreasing of hydrogen saturation limit. Optimal values of temperature (400 °C) and pressure (2 atm) for pure titanium powder hydrogenation have been determined.

Effect of yttria–titanium shell–core structured powder on strength and ageing of zirconia/titanium composites

Commercially pure titanium powder was modified by a two-step procedure involving attrition milling and subsequent coating with yttria by sol–gel. Lamellar titanium particles with a high aspect ratio were obtained by mechanical grinding. The existence of an yttria layer covering the milled titanium particles (shell–core structure) was corroborated by X-ray photoelectron spectroscopy. Zirconia/titanium (25vol% titanium) compact specimens were processed by a wet route using the modified titanium powder, spark plasma sintered, and then characterized in terms of mechanical strength and ageing. A reinforcement mechanism arises from the special shape and disposition of the metallic particles. The stable Y2O3 barrier prevents excessive formation of side products at the metal–ceramic interface. Hence, our innovative procedure allows to develop a new ceramic–matrix composite in the interesting zirconia/titanium system with improved mechanical properties and controlled ageing compared to the composites made with commercially pure titanium.

Effect of Processing Parameters on the Properties of Metal Injection Moulded Titanium Dental Implants

Metal injection moulding (MIM) is a well-established, cost-effective method of fabricating small-to-moderate size near net-shape metal components. MIM is increasingly being employed as a process for fabricating orthopaedic and dental products with complicated shapes. In this study, commercially pure titanium (CP-Ti) powder has been used to fabricate dental implants via MIM. The CP-Ti powder was mixed with binders containing Polyethylene glycol (PEG), High Density Polyethylene (HDPE) and stearic acid (SA) to form the MIM feedstock. Commercially available feedstock was also used to fabricate MIM implants. The MIM compacts were then subjected to debinding and sintering, and then the mechanical and chemical properties of the compacts were investigated for their suitability for dental implantology. The effect of the MIM processing variables on the surface roughness of CP-Ti was also investigated and studies for biocompatibility were carried out using in-vitro cell culture. The results showed that the mechanical and chemical properties of the sintered components were within ASTM Grade MIM 2 and Grade MIM 3 (ASTM F2989 − 13) specifications for titanium. The results also showed that the implants produced by MIM appeared to meet basic biocompatibility requirements. It was concluded that dental implant prototypes may be fabricated successfully using MIM and this approach offers greater opportunities for future manufacturing.

Custom-made titanium devices as membranes for bone augmentation in implant treatment: Modeling accuracy of titanium products constructed with selective laser melting

ObjectiveThe purpose of this study was to verify the modeling accuracy of various products, and to produce custom-made devices for bone augmentation in individual patients requiring implantation. Materials and methodsTwo-(2D) and three-dimensional (3D) specimens and custom-made devices that were designed as membranes for guided bone regeneration (GBR) were produced using a computer-aided design (CAD) and rapid prototyping (RP) method. The CAD design was produced using a 3D printing machine and selective laser melting (SLM) with pure titanium (Ti) powder. The modeling accuracy was evaluated with regard to: the dimensional accuracy of the 2D and 3D specimens; the accuracy of pore structure of the 2D specimens; the accuracy of porosity of the 3D specimens; and the error between CAD design and the scanned real product by overlapped images. ResultsThe accuracy of the 2D and 3D specimens indicated precise results in various parameters, which were tolerant in ISO 2768-1. The error of overlapped images between the CAD and scanned data indicated that accuracy was sufficient for GBR. In integrating area of all devices, the maximum and average error were 292 and 139 μm, respectively. ConclusionsHigh modeling accuracy can be achieved in various products using the CAD/RP-SLM method. These results suggest the possibility of clinical applications.

Additive-manufactured patient-specific titanium templates for thoracic pedicle screw placement: novel design with reduced contact area.

Image-based navigational patient-specific templates (PSTs) for pedicle screw (PS) placement have been described. With recent advances in three-dimensional computer-aided designs and additive manufacturing technology, various PST designs have been reported, although the template designs were not optimized. We have developed a novel PST design that reduces the contact area without sacrificing stability. It avoids susceptibility to intervening soft tissue, template geometric inaccuracy, and difficulty during template fitting. Fourteen candidate locations on the posterior aspect of the vertebra were evaluated. Among them, locations that had high reproducibility on computed tomography (CT) images and facilitated accurate PS placement were selected for the final PST design. An additive manufacturing machine (EOSINT M270) fabricated the PSTs using commercially pure titanium powder. For the clinical study, 36 scoliosis patients and 4 patients with ossification of the posterior longitudinal ligament (OPLL) were treated with thoracic PSs using our newly developed PSTs. We intraoperatively and postoperatively evaluated the accuracy of the PS hole created by the PST. Based on the segmentation reproducibility and stability analyses, we selected seven small, round contact points for our PST: bilateral superior and inferior points on the transverse process base, bilateral inferior points on the laminar, and a superior point on the spinous process. Clinically, the success rates of PS placement using this PST design were 98.6% (414/420) for scoliosis patients and 100% (46/46) for OPLL patients. This study provides a useful design concept for the development and introduction of patient-specific navigational templates for placing PSs.

Modelling compaction behaviour of nickel–phosphorus and nickel–boron electroless coated titanium powders

Electroless plating is used as an alternative approach to alloying the commercially pure titanium powders. Two types of irregularly shaped powders, which differ in particle size distribution, are coated with nickel–phosphorus (Ni–P) and nickel–boron (Ni–B). A novel method, combining aspects of the Kawakita and Alderborn approaches, has been employed in order to understand compaction behaviour. The overall consolidation is described by a Kawakita–Ludde relationship, and the transition pressures which demarcate the limits of rearrangement only and plastic deformation only are identified using a modification of the Alderborn relationship. A significant increase in green strength is achieved with the Ni–B coated powders, and this is attributed to a modification of friction conditions and the number of possible contacts, which lead to an increased contribution from plastic deformation. The Mohr–Coulomb model and Ohyane equations are used to describe the contribution of the number of contacts on green strength.

Sintering of Titanium Hydride Powder Compaction

Sintering by the TiH2 and Ti powder compaction was performed at 1423∼1623K for 2hours at 1.33x10-3Pa. The sinter-ability of TiH2 powder was higher than that of pure titanium powder, leading to near 99% of relative density, which was the competing level with that by HIP process. In the direct sintering of TiH2 powder compaction, the interstitial hydrogen atoms was released before sintering through the grain boundaries and meet the titanium oxide phase existing in the grain boundaries as the film forms. We found thermodynamically there that the hydrogen atoms could effectively reduce the titanium oxide existing on the powder surfaces or grain boundaries with a considerable driving force of about -250kJ/mole. Such a self-reduction process by hydrogen atoms makes the grain boundaries very clean with oxide-free condition and helpful for sintering. Moreover, the de-hydrogenated titanium regions near grain boundaries could become unstable due to the formation of many vacancy defects by the release of hydrogen and also evoke the sintering ability.

Biomechanical evaluation of porous titanium implants (CpTi) fabricated by powder technology

It may be an important prospective clinical use of manufacturing of porous implant for clinical situations, such as cases of limitation in bone height, low bone density .The small segment of porous implant an effective osseointegration allows increasing in contact area provided for small segmented porous provided by its surface configuration. This study was done to Fabricate porous titanium implants by powder technology, as well as the observation of removal torque values of porous titanium implants compared to smooth titanium implants. Materials and methods: Twenty porous titanium implants (3.2mm in diameter and 8mm in length) were manufactured by powder technology using commercially pure titanium powder of ≤75um particles size, with polyvinyl alcohol powder of 212-300um particle size, as a space holder, by volume ratio (70:30) % respectively. The mixed powder was compacted using punch and die set -specially designed for this study -under 20 bar then sintering at 900 o C by the use of argon gas. Twenty smooth titanium implants were prepared of (3.2mm in diameter and 8mm in length) by lathing of commercially pure titanium rod as a control group. The implants were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM), as well as estimation of porosity percentage. For each tibia of the 20 white New Zealand rabbits, one implant of each type (one porous in right, and the smooth in left tibia), were inserted through surgical procedure carried under serial condition. Mechanical test was performed to evaluate the bone- implant interface, after (2 and 6 weeks) healing periods . Results: Porous implants were obtained successfully by powder technology with 52% porosity and pore size 210um 17±. The porous implant showed significantly higher removal torque values when compared to smooth implants at the two different intervals of examination (2,6 weeks) , this proved to be statistically highly significant, also a highly significant difference was noticed for the means of the torque removal values in the same group at different implantation , with no evidence of clinical features of inflammatory reaction with both . Conclusions: Powder technology seemed to be particularly advantageous in fabrication of porous titanium. Porous implant show an increasing bone ingrowth compared with the smooth type represented by higher removal torque for both healing periods (2, 6) weeks .

S0410104 高濃度窒素固溶純チタン粉末押出材における高強度と高延性の両立

S0410104 高濃度窒素固溶純チタン粉末押出材における高強度と高延性の両立

Characterization of Titanium Powders Processed at Different Temperatures

Titanium is the most adequate metallic material for orthopedic or dental implants fabrication, due to a very favorable combination of properties, when compared with other metals, such as good corrosion resistance, good mechanical properties, relatively low density, elasticity modulus close to that of bone and good biocompatibility, which assures good adhesion/integration to bone. Powder metallurgy has been used for titanium based implants fabrication due to advantages such as the production of more complex shapes and reduction of machining operation. In this work, compacted pure titanium powders, consolidated by rolling at different temperatures, were characterized by means of optical microscopy, Field Emission Scanning Electron Microscopy (FESEM) with Electron Back Scattering Diffraction (EBSD) analysis, automatic image analysis and hardness tests. The hardness of rolled samples increased from 200 to 400oC , which indicated that 300 to 400°C is the most adequate temperature range for this processing route, since it allowed obtaining low porosity with satisfactory and relatively high hardness.

Effects of sintering parameters on the hardness and microstructures of bulk bimodal titanium

Spark plasma sintering was used to condense commercially pure titanium powder into bulk samples. The effects of sintering temperature, holding time, pressure and heating rate on the density, chemical constitution, microstructure and hardness were systematically investigated. The results indicate that (1) applying high pressure and increasing the sintering temperature accelerate the densification process significantly, while the heating rate and holding time show less important effects. (2) The as-sintered samples have bimodal grain size distributions (consisting of both micro-sized grains and nanocrystalline grains). (3) The as-sintered samples exhibit extremely high hardness compared to as-cast pure titanium and nanocrystalline/ultrafine-grained pure titanium fabricated by other methods. (4) A self-cleaning effect exists during the sintering process, resulted from oxide decomposition.

Morphology and structural development of reduced anatase-TiO2 by pure Ti powder upon annealing and nitridation: Synthesis of TiOx and TiOxNy powders

It is well known that nitriding of titanium is suitable for surface coating of biomaterials and in other applications such as anti-reflective coating, while oxygen-rich titanium oxynitride has been applied in thin film resistors and photocatalysis. Thus in this work anatase was reduced with pure titanium powder during annealing in argon. This was done to avoid any metallic contamination and unwanted residual metal doping. As a result, interesting and different types of particle morphology were synthesized when the pre-milled elemental anatase and titanium powders were mixed. The formation of metastable face centred cubic and monoclinic titanium monoxide was detected by the X-ray diffraction technique. The phases were confirmed by energy dispersive X-ray spectroscopy analysis. Raman analysis revealed weak intensity peaks for samples annealed in argon as compared to those annealed under nitrogen.

Laser surface modification of Ti and TiC coatings on magnesium alloy

In order to enhance the surface properties of magnesium alloy, a highly intense laser surface melting process following plasma spraying of Ti or TiC on AZ31 alloy were employed. When laser surface melting was applied to Ti coated magnesium alloy, the formation of fine Ti particle dispersed surface layer on the substrate occurred. The corrosion potential of the AZ31 alloy with Ti dispersed surface was significantly increased in 3.5 wt % NaCl solution. Additionally, an improved hardness was observed for the laser treated specimens as compared to the untreated AZ31 alloy. Laser melting process following plasma thermal deposition was also applied for obtaining in situ TiC coating layer on AZ31 alloy. The TiC coating layer could be successfully formed via in situ reaction between pure titanium and carbon powders. Incomplete TiC formation was observed in the plasma sprayed specimen, while completely transformed TiC layer was found after post laser melting process. It was also confirmed that the laser post treatment induced enhanced adhesion strength between the coating and the substrate.

Process Models for Press-and-Sinter Titanium

Two commercially pure (CP) titanium powders, with mean particle sizes of 78 and 32 μm, respectively, were used to manufacture titanium samples via the press-and-sinter powder metallurgy process. Compaction pressures ranging from 300 to 500 MPa were used to compact the powders into cylindrical and rectangular forms. The green samples were sintered for 2 hours under high vacuum, 10-6 mbar, at 1100, 1200 and 1300 °C, respectively. Green density and green strength data were collected from the compacted samples, and sintered density, sintered strength and microstructure images were collected from the sintered samples. These data were used to characterise process models for the compressibility of the powders, and for the sinter densification, using the Master Sintering Curve (MSC) model. The results show that particle size influences the processing at both the compaction and sintering step. In modelling these two processes, separate MSC models must be characterised and each used individually to predict each one’s final sintered density. It is shown that if the densification parameter is used to characterise the sintering model, a unified Master Densification Curve (MDC) is found. The modified MDC model can be used to predict the final sintered density regardless of the initial green density or mean particle size of the powder.

Influence of Powder Particle Size Distribution on the Properties of Press-and-Sintered Titanium and Ti-6Al-4V Preforms

The potential to control the final properties, as measured by density, strength and microstructure, of press-and-sintered titanium and master alloy Ti-6Al-4V is investigated by designing and evaluating bimodal particle size distributions of the relevant powders. Ratios of 1/3, 2/3 and 1/1 by volume of coarse to fine powders, as determined by particle size peaks, were blended from -200 and -100 mesh commercially pure titanium powders and -200 mesh 60Al-40V master alloy powder, in the case of Ti-6Al-4V. The powder blends were uniaxially compacted at 350, 400 and 450 MPa, and the green specimens were sintered under high vacuum for two hours at 1300°C. The results support theoretical prediction of green and sintered density based on the ratio of the volume percentage of coarse to fine powder; green density increases as the ratio of coarse powder increases for both the pure and alloy titanium, while the sinter density similarly decreases for the pure titanium. Microstructural observations of the sintered specimens show that the pore size decreases, and the pore shape becomes more rounded, as the ratio of fine powder increases. In order to extend the study to find the optimal packing ratio, and potentially the optimal blend for densification, further refinement of the initial powder particle size distributions is needed.

Thermal behavior during selective laser melting of commercially pure titanium powder: Numerical simulation and experimental study

A three-dimensional model was developed for studying thermal behavior during selective laser melting (SLM) of commercially pure titanium (CP Ti) powder. The effects of scan speed and laser power on SLM thermal behavior were investigated. The results showed that the average temperature of the powder bed gradually increased during the SLM process, caused by a heat accumulation effect. The maximum molten pool temperature (2248°C) and liquid lifetime (1.47ms) were obtained for a successful SLM process for a laser power of 150W and a laser scan speed of 100mm/s. The temperature gradient in the molten pool increased slightly (from 1.03×104 to 1.07×104°C/mm in the direction perpendicular to the scanning path; from 1.21×104 to 1.28×104°C/mm in the thickness direction) when the scan speed was increased from 50 to 200mm/s, but increased significantly (from 1.29×104 to 8.24×104°C/mm in the direction perpendicular to the scanning path; from 1.53×104 to 9.84×104°C/mm in the thickness direction) when the laser power was increased from 100 to 200W. The width and depth of the molten pool decreased (width from 137.1 to 93.8μm, depth from 64.2 to 38.5μm) when the scan speed was increased from 50 to 200mm/s, but increased (width from 71.2 to 141.4μm, depth from 32.7 to 67.3μm) when the laser power was increased from 100 to 200W. Experimental SLM of CP Ti powder was carried out under different laser processing conditions and the microstructure of SLM-produced parts was investigated to demonstrate the reliability of the physical model and simulation results.