Titanium Powder Research Articles

A method for the preparation of spherical titanium powder for additive manufacturing

In this work, a new method was designed and developed to produce spherical Ti powder for additive manufacturing (AM) process. In this method, copper was introduced to form Ti-Cu alloy with a low melting point, and spherical Ti powder was prepared by combining with several low-cost processing techniques, including solid-liquid interface dewetting spheroidization, dealloying, sintering and de‑oxygenation processes. The spherical Ti powder prepared by this method shows a low oxygen content (<0.1 wt%), and the particle size was controlled between 15 and 75 μm. Compared with the current mature technology of the preparation of spherical titanium powder, this method provideds unique advantages during the preparation of small-sized spherical Ti powder (<30 μm), which meets the requirements of high-quality AM technology. • A new method was designed and developed to produce spherical Ti powder. • Techniques and raw materials are low cost. • Spherical Ti powder with controllable size distribution and low oxygen content can be produced.

Preparation of low-oxygen Ti powder from TiO2 through combining self-propagating high temperature synthesis and electrodeoxidation

An effective method was reported to prepare low-oxygen Ti powder, which included two experimental steps: the fast conversion of TiO2 to TiOx<1 powder by self-propagating high-temperature synthesis (SHS) process and the generation of low-oxygen Ti powder by electrodeoxidizing TiOx<1 powder at the cathode in molten CaCl2. The key intermediate steps were analyzed by XRD, SEM and electrochemical testing techniques. The results demonstrated that TiOx<1 powder (TiO0.325 and TiO0.97) was generated after acid leaching MgO in SHS products with TiO2/Mg molar ratio of 1:2, and the TiOx<1 powder with 16.3 wt.% oxygen could be transformed into pure titanium powder with 0.121 wt.% oxygen by electrodeoxidation at a constant potential of -3.3 V for 10 h. The electrodeoxidation of TiOx<1 powder in CaCl2 molten salt follows the step-by-step deoxidation mode, and the lattice of TiOx<1 powder after electrodeoxidation shrinks.

Changes in the Surface Properties of Powder Titanium under Mechanoactivation

Changes in the Surface Properties of Powder Titanium under Mechanoactivation

The Effect of the Parameters on Al 7075 Coated with MAO Method by Adding Nano Ti-Powder

Coating processes are carried out in many areas of industry to improve the surface properties of materials such as wear and corrosion resistance or appearance. One of these coating processes is ceramic-based surface coatings. In order to obtain harder, denser and more uniform coatings, the substrate material is coated with a ceramic-based material at the desired thickness. In this study, 7075 series aluminum was coated with nano Ti powder and non-additive micro arc oxidation (MAO) method in a solution consisting of KOH, NaAlO2 and Na3PO4, and the effects of process parameters on coating thickness and wear behavior were experimentally investigated and the results were analyzed. According to the results obtained, it was observed that as the coating voltage, frequency and coating time increased, the wear rate decreased and a harder structure against wear is obtained. In addition, it was determined that the samples with nano titanium powder were less worn than the non-additive samples. According to SEM, EDX and XRD analyses, Al2O3 phase was observed in the coatings made without adding titanium particles; It has been observed that in addition to the Al2O3 main phase, TiO2 and SiO phases are also formed in titanium doped coatings.

Studying Titanium Powder Obtained by SHS Hydrogenation and Dehydrogenation Using a Vacuum Furnace

Studying Titanium Powder Obtained by SHS Hydrogenation and Dehydrogenation Using a Vacuum Furnace

Sharp luminescence system in titanium dioxide with zero-phonon transition at 1.573 eV

In this paper, we discuss near-IR steady-state and time-resolved low-temperature (5 K) luminescence of crystalline titanium dioxide (TiO2) powders with different particle sizes. Upon optical excitation with quantum energy close to 3.1 eV, the near-IR luminescence of all the powders reveals a very similar characteristic spectrum, which includes a narrow 1.573 eV line, a set of wider peaks in 1.565–1.545 eV range, and a broad band at ∼1.42 eV. The spectrum remains unchanged when using different excitation quanta, thus indicating that all components are governed by the same luminescence system. It is also confirmed by identic two-exponential luminescence decays with characteristic decay times 70 μs and 400 μs observed for all parts of the spectrum. The properties of the luminescent system are not sensitive to the crystallite size reduction to 10 nm, and its intensity sharply increases after annealing converting the anatase phase into rutile. A comparison of the spectrum with TiO2 phonon density of states indicates that 1.573 eV peak is a zero-phonon transition, and 1.545–1.565 eV structure is due to interaction with bulk phonons of rutile phase. The band at 1.42 eV seems to be due to non-adiabatic electron-phonon coupling. The data obtained clearly indicates that the luminescent system is governed by inner shells of transition elements located in rutile lattice. This transition element can be vanadium as it follows from ICP-MS data and theoretical modeling. The detected luminescent system provides a convenient optical marker of TiO2, including nanoform, and thus can be useful for some applications related to medicine, biology, as well as the food industry.

Compressive Mechanical Properties and Shock-Induced Reaction Behavior of Zr/PTFE and Ti/PTFE Reactive Materials.

Existing research on PTFE-based reactive materials (RMs) mostly focuses on Al/PTFE RMs. To explore further possibilities of formulation, the reactive metal components in the RMs can be replaced. In this paper, Zr/PTFE and Ti/PTFE RMs were prepared by cold isostatic pressing and vacuum sintering. The static and dynamic compressive mechanical properties of Zr/PTFE and Ti/PTFE RMs were investigated at different strain rates. The results show that the introduction of zirconium powder and titanium powder can increase the strength of the material under dynamic loading. Meanwhile, a modified J-C model considering strain and strain rate coupling was proposed. The parameters of the modified J-C model of Zr/PTFE and Ti/PTFE RMs were determined, which can describe and predict plastic flow stress. To characterize the impact-induced reaction behavior of Zr/PTFE and Ti/PTFE RMs, a quasi-sealed test chamber was used to measure the over-pressure induced by the exothermic reaction. The energy release characteristics of both materials were more intense under the higher impact.

Influence of Addition of Ti Particles and Processing Condition on Microstructure and Properties of Selectively Laser-Melted Invar 36 Alloy.

Invar 36 exhibits extremely low thermal expansion coefficients at low temperatures but also low yield strength (YS), which greatly restricts its application as a structural material. In this study, a small fraction of pure titanium powder particles was added into Invar 36 by powder mixing and selective laser melting (SLM) with the aim of further improving tensile strengths of Invar 36. It was found that increased laser power led to increased grain size and to slight decrease in YS in Invar 36. During SLM, amorphous SiO2 nanoparticles were formed and homogeneously distributed in Invar 36. With the addition of 2 at% Ti powder particles, grains became larger and the crystallographic texture along <001> and <111> increased to some extent. Moreover, the bottom of solidified melt pools was segregated with Ti while the matrix was homogeneously decorated by a great number of nano-sized spherical Ti2O3 particles. These particles were found to have effectively impeded dislocation motion during plastic deformation, leading to significant improvement in 0.2% YS and ultimate tensile strength. The above precipitation led to consumption of a small amount of Ni from the matrix, which caused a minor compromise in thermal expansion properties. Nonetheless, the newly synthesized Invar 36-Ti alloy still exhibits low thermal expansion coefficients at low temperatures and remarkably enhanced tensile strengths.

Outcomes of mandibular reconstruction using three-dimensional custom-made porous titanium prostheses

BackgroundOur aim was to report the long-term outcomes of mandibular reconstruction using CAD-CAM-designed 3D-printed porous titanium implants in patients not amenable to a free vascularized fibula flap reconstruction. MethodsThe implants were designed with ProPlan CMF® 2.2 software and manufactured with a Selective Laser Melting (SLM) “layer-by-layer” 3D-printing of pure porous titanium powder beds. Primary endpoints were implant exposure and implant removal calculated using Gray's tests. Secondary endpoints were predictive factors of implant exposure and implant removal, and rates of dental rehabilitation. ResultsThirty-six patients were operated between 2015 and 2017 and were included in this study. Reconstruction using a porous titanium 3D-printed implant was proposed due to medical contraindication for a fibula free flap (n = 13), due to the failure of a previous fibula free flap reconstruction (n = 7), or due to refusal of a fibula free flap reconstruction by the patient (n = 16). The medical indications for mandibular reconstruction were a primary tumor requiring mandibulectomy in nine patients, mandibular osteoradionecrosis requiring mandibulectomy in nineteen patients, and secondary reconstruction in eight patients. The 2-year rates of implant exposure and implant removal were 69.4% and 52.8%. Reconstruction of the symphysis was a high-risk exposure variable (OR 30; p = 0.0003). Only one patient underwent a successful dental rehabilitation. ConclusionThe use of a porous titanium 3D- implant for mandibular reconstruction in head and neck cancer patients resulted in high rates of implant exposure and of implant removal, notably when symphysis involvement.

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

PurposeThe purpose of this paper is to investigate the effect of remelting each layer on the homogeneity of nickel-titanium (NiTi) parts fabricated from elemental nickel and titanium powders using laser powder bed fusion (LPBF). In addition, the influence of manufacturing parameters and different melting strategies, including multiple cycles of remelting, on printability and macro defects, such as pore and crack formation, have been investigated.Design/methodology/approachAn LPBF process was used to manufacture NiTi alloy from elementally blended powders and was evaluated with the use of a remelting scanning strategy to improve the homogeneity of fabricated specimens. Furthermore, both single melt and up to two remeltings were used.FindingsThe results indicate that remelting can be beneficial for density improvement as well as chemical and phase composition homogenization. Backscattered electron mode in scanning electron microscope showed a reduction in the presence of unmixed Ni and Ti elemental powders in response to increasing the number of remelts. The microhardness values of NiTi parts for the different numbers of melts studied were similar and ranged from 487 to 495 HV. Nevertheless, it was observed that measurement error decreases as the number of remelts increases, suggesting an increase in chemical and phase composition homogeneity. However, X-ray diffraction analysis revealed the presence of multiple phases regardless of the number of melt runs.Originality/valueFor the first time, to the best of the authors’ knowledge, elementally blended NiTi powders were fabricated via LPBF using remelting scanning strategies.

Enhanced mechanical properties of in situ synthesized TiC/Ti composites by pulsed laser directed energy deposition

Titanium matrix composites (TMCs) have attracted extensive attention of researchers due to their excellent properties. However, the strength and ductility of TMCs hardly co-exist and show a trade-off between each other. To overcome the problem, in this study, with feeding the commerically pure titanium (CP–Ti) powder decorated by nano carbon, TiC reinforced Ti matrix composites were synthesized in situ by Pulsed Laser Directed Energy Deposition (PLDED). As the C content increases, the size, content and morphology of the TiC particles gradually change and the irregular block α phase transform to lath α phase in the matrix. As for Ti+0.6 wt% C, due to the strengthening effect of dispersed eutectic TiC and the evolution of morphology of α phase in the matrix, the ultimate tensile strength of TiC/Ti composites (940 MPa) is ∼84.3% and ∼108.9% higher than that of the PLDED and forged CP-Ti respectively, while retaining excellent elongation to failure (18.9%), which effectively solves the problem of strong-plastic contradiction existing in the preparation of TMCs. And at this carbon content, the friction and wear properties of the composites are effectively improved, the friction coefficient (0.26) is 55% lower than that of CP-Ti (0.58) obtained under the same process. This work shows a great potential way to significantly improve the mechanical properties of titanium alloys.

Grain growth and phase transformation of nano-sized titanium dioxide powder during heat treatment and spark plasma sintering

The control of nanostructures is crucial for enhancing the thermoelectric properties of materials. In this work, the grain growth and phase transformation of different nano-sized titanium dioxide (TiO2) powders were investigated during heat treatment and spark plasma sintering. First, the thermal behaviors of TiO2 powders with different particle sizes during heat treatment, such as grain growth, phase transformation, and adsorption properties, were studied. The results showed that the phase transformation of 7 nm anatase TiO2 occurred more easily, and the rutile phase content increased with increasing heat treatment temperature. The grain growth of 7 nm anatase TiO2 occurred at low temperature (i.e., 873 K), even the grain size increased by 13-fold at 1123 K (i.e., the phase transformation temperature). Thermogravimetry results suggested that the 7 nm anatase TiO2 powder had a greater adsorption characteristic owing to its large specific surface area. Moreover, TiO2 compacts with and without graphite were fabricated using spark plasma sintering. The results indicated that a lower sintering temperature was beneficial for maintaining the nanostructure, whereas the addition of graphite powder promoted grain growth. Furthermore, the thermal conductivity was reduced owing to the nanostructure, and the phonon thermal conductivity accounted for a dominant proportion of the total thermal conductivity. Consequently, the lowest thermal conductivity was 1.1 Wm−1K−1 at 973 K for the nanostructured compact sintered at 1073 K, which is approximately 50% lower than that of the microstructured compact sintered at 1273 K.

Evaluation of NOx removal performance of foam composites with titanium dioxide and active carbon

• Activated carbon (AC) and titanium dioxide (TiO 2 ) foam composites were fabricated. • The NO X removal performances and micropore structures of the composites were studied. • The TiO 2 and AC replacement ratios and specimen thickness and density were varied. • NO X removal improved with increasing TiO 2 replacement but decreased with density. • The NO X removal was the highest with 15% AC replacement and varied with UV intensity. In this study, the nitrogen oxide (NO X ) removal performances and micropore structures of foam composites with activated carbon (AC) and titanium dioxide (TiO 2 ) powder were investigated. AC was used to increase the NO X removal efficiency through TiO 2 powder by increasing the specific surface areas of the foam composites. The foam composites were fabricated with the replacement ratios of TiO 2 powder and AC, as well as the specimen thickness and density, as variables. The NO X removal performance was evaluated according to the test method presented in ISO-22197. The specific surface area of the foam composite tended to increase with increasing AC content but decreased by AC content more than 15 %. The NO X removal efficiency was the highest when the AC replacement ratio was 15 %. The NO X removal efficiency improved as the replacement ratio of TiO 2 powder increased but decreased as the density of the foam composite increased. The NO X removal efficiency was the highest when the thickness of the specimen was 20 mm and was greatly affected by the ultraviolet light intensity.

MULTI-RESPONSE OPTIMIZATION OF DIELECTRIC FLUID MIXTURE IN EDM USING GREY RELATIONAL ANALYSIS (GRA) IN TAGUCHI METHOD

In the current study, combining the powder with dielectric fluid in electrical discharge machining (PMEDM) is a very fascinating technological approach. This approach is the most effective at increasing both productivity and the quality of a machined surface at the same time. The Taguchi–GRA approach was used to optimize the surface roughness (SR), material removal rate (MRR), and micro-hardness of a machined surface (HV) in electrical discharge machining of die steels in dielectric fluid with mixed powder. Workpiece materials (with 3 levels such as SKD61, SKD11, and SKT4), electrode materials (with 2 levels such as copper, and graphite), pulse-on time, electrode polarity, current, pulse-off time, and titanium powder concentration were all used in the study. The effect on the ideal results was also evaluated using some interaction pairings among the process parameters. Powder concentration, electrode material, electrode polarity, current, pulse-on time, pulse-off time, and Interaction between workpiece material and powder concentration were obtained to be significant in the ideal condition, where larger MRR and HV are wanted (as per the HB criterion), but lower values are desired for the remaining responses, such as surface roughness (SR). Powder concentration was also discovered to be a major component, however, it only accounts for 8.35 percent of the ideal condition. MRR = 54.36 mm3/min, SR = 5.65 m, and HV =832.66 HV were the best quality attributes based on the grey grade.

Effect of Process Parameters on Properties of Titanium Alloy during Thermal Simulation Deformation

In this paper, aiming at the heat resistance and thermal deformation process of titanium matrix composites 0 vol.%, 2.5.vol.%, 5.vol.%. Thermal simulation experiment of titanium matrix composites with different (TiB+TiC) strengthening phase content. The measurement accuracy of material displacement is 0.01 mm. The compression is 70%, and the strain rate is 0.1 mm/s and 0.01 mm/s respectively. Compression tests at different strain rates and temperatures were carried out. The experimental results show that when the (TiB+TiC) 5vol% titanium composite is deformed at 0.01mm/s low strain rate, the peak stresses corresponding to 25°C, 250°C,350 °C and 500°C are increased to 1096MPa, 835MPa, 646MPa and 416MPa respectively. Under the condition of high strain rate of 0.1mm/s, the peak stresses corresponding to 25 °C, 250 °C, 350 °C and 500 °C are increased to 1230 MPa, 896 MPa, 723 MPa and 471 MPa respectively. The deformation law of stress rheological curve is roughly the same, and the high temperature zone has good plastic deformation ability. The titanium matrix composite has high compression rheological mechanical properties and good high-temperature plastic deformation ability. It is the preferred material component for the preparation of titanium matrix composite and powder forging.

Effect of Alloying Elements on Strengthening Phase and Solidification Structure of Ti-Al-Mo-Zr Titanium Alloy

This paper mainly studies the composition of strengthening phase, characteristic precipitation temperature and composition range of strengthening phase in Ti-Al-Mo-Zr-Si medical titanium alloy, and the influence of element changes on the content and microstructure of strengthening phase. Promote the formulation of thermodynamic process of titanium alloy powder metallurgy, as well as the formulation of alloy hot working and solid solution aging process. In this paper, Panda thermodynamic software is used to calculate the multicomponent alloy thermodynamics and multicomponent phase diagram of titanium alloy materials. The effects of Al, Mo, Zr, Si and other elements on the precipitation of strengthening phase and the phase transformation content of solidification structure were obtained. It is found that the content of Mo is more than 2 wt.% β phase transition precipitation angle. Meanwhile, in order to avoid the excess of precipitates such as Mo5Si3 and M3Si, the content of Mo should be less than 4.6 wt.%. The content of Zr can be maintained at about 1.5 wt.%. If the aging precipitation of the material is considered, it can be controlled to be less than 2 wt.%. The content of this paper is the basis and improvement of titanium powder metallurgy technology and rapid prototyping technology.

Effect of Sintering Temperature on Properties of Carbon Fiber-Reinforced Titanium Matrix Composites.

Carbon fiber-reinforced titanium matrix composites were prepared by powder metallurgy. Carbon fiber (CF) powder and titanium (Ti) powder are mixed, pressed, and then sintered at a high temperature of 1300–1500 °C. The morphology and conductivity of carbon fiber-reinforced titanium matrix (Ti-CF) composites were studied. When the temperature range of the Ti-CF composites was from 1300 to 1500 °C, the porosity and resistivity first decreased and then increased. When the sintering temperature was 1350 °C, the diffraction peak of the sample was the strongest, the porosity was the smallest (4.16%), and the resistivity was the smallest (2.7 MΩ·mm). CFs have a very good strengthening effect on titanium-based composite materials.

The Influence of Dimensions and Powder Recycling on the Roughness and Mechanical Properties of Ti-6Al-4V Parts Fabricated by Laser Powder Bed Fusion.

Powder bed fusion technology has undergone a remarkable amount of development in recent years in the field of medical implants due to the advantages associated with it. In many implant applications that demand loads in parts with a high degree of roughness and small dimensions, the mechanical properties, especially fatigue properties, play a key role in the success of the implants. One of the most used materials in this field is Ti-6Al-4V. On the other hand, the high cost of titanium powders makes it necessary to search for suitable powder recycling strategies. In this work, the effects of dimensions and powder recycling on the roughness and the mechanical properties of cylinder specimens were obtained from tensile static and fatigue tests of Ti-6Al4V Extra-Low Interstitial (ELI) parts. Four types of specimens were fabricated by laser powder bed fusion (two dimensions (section diameters of 2 mm and 5 mm) with new powder and with recycled powder). Results show that the oxygen concentration increased with recycling. No significant effects of recycling were observed on the monotonic tensile strength specimens. However, specimens fabricated with recycled powder showed greater roughness, lower ductility, and lower fatigue strength than those fabricated with new powder. On the other hand, the 5-mm-diameter specimens showed slightly better fatigue behavior than the 2-mm-diameter ones.

DEVELOPMENT OF TITANIUM-THERMITE MIXTURE FOR WELDING

The influence of reducing metals on the metallurgical processes of thermite welding has been studied. Iron scale and powdery materials were used as starting materials for the metallothermic mixture: titanium powder PTS according to TU 15‒1958, aluminum powder PA-2 according to GOST 6058‒73. Aluminum gas purification dust was introduced into the composition of the metallothermic mixture. The chemical composition of the metal was determined by the atomic emission method using the DFS-71 spectrometer according to GOST RISO 14284‒2009, the slag composition was determined by the X-ray fluorescence method on the Shimadzu XRF-1800 spectrometer according to GOST 28033‒89. The composition of the titanothermite mixture has been developed, which ensures the production of dense metal. The addition of a small amount of aluminum powder to the composition of the titanium-thermite mixture ensures the completeness of the interaction and reduction of iron scale, at the same time, the amount of molten metal increases. The introduction of aluminum gas purification dust into the thermite mixture as a flux reduces gas emission during thermal processes. In addition, the addition of a carbon-fluorine-containing flux additive increases the carbon content in the resulting metal and improves its mechanical properties.

Titanium Powder 3D-Printing Technology for a Novel Keratoprosthesis in Alkali-Burned Rabbits.

PurposeTo evaluate the surgical technique, clinical performance, and biocompatibility of a novel keratoprosthesis (KPro) named KPro of Brazil (KoBra) in an alkali-burned rabbit model.MethodsTwo-piece three-dimensional-printed titanium powder and polymethyl methacrylate KPros were implanted into 14 alkali-burned corneas of 14 rabbits using an autologous full-thickness corneal graft as the KPro carrier. Rabbits were examined weekly for 12 months to evaluate retention and postoperative complications. Anterior segment optical coherence tomography (AS-OCT) and scanning electron microscopy (SEM) were performed at the end of the experiment to evaluate the relationship between the KoBra and the carrier graft.ResultsAll surgeries were performed without intraoperative complications, and the immediate postoperative period was uneventful. In 12 eyes (85.7%), the implanted KPros integrated into the operated eyes and maintained clear optics without extrusion or further complications over 12 months. Two eyes presented late postoperative complications that progressed to KPro extrusion: one had a presumed infectious keratitis, and the other had sterile stromal necrosis. AS-OCT demonstrated the correct relationship of the device and carrier graft in all remaining animals at the final follow-up. SEM findings indicate the integration of the porous structure of the back plate into the surrounding tissue.ConclusionsClinical evaluations, AS-OCT, and SEM findings indicate good biointegr-ation of the implanted device into the corneal carrier graft. KoBra has the advantage of using recipients’ own corneas as the prosthesis supporter, and its surgical procedure is relatively simple and safe.Translational RelevanceTitanium three-dimensional-printed technology used in an animal limbal stem-cell deficiency model holds great promise for the treatment of corneal blindness in humans.