Pure Titanium Powder Research Articles

Microwave-assisted fabrication of titanium implants with controlled surface topography for rapid bone healing.

Morphological surface modifications have been reported to enhance the performance of biomedical implants. However, current methods of introducing graded porosity involves postprocessing techniques that lead to formation of microcracks, delamination, loss of fatigue strength, and, overall, poor mechanical properties. To address these issues, we developed a microwave sintering procedure whereby pure titanium powder can be readily densified into implants with graded porosity in a single step. Using this approach, surface topography of implants can be closely controlled to have a distinctive combination of surface area, pore size, and surface roughness. In this study, the effect of various surface topographies on in vitro response of neonatal rat calvarial osteoblast in terms of attachment and proliferation is studied. Certain graded surfaces nearly double the chance of cell viability in early stages (∼one month) and are therefore expected to improve the rate of healing. On the other hand, while the osteoblast morphology significantly differs in each sample at different periods, there is no straightforward correlation between early proliferation and quantitative surface parameters such as average roughness or surface area. This indicates that the nature of cell-surface interactions likely depends on other factors, including spatial parameters.

Effects of various sintering methods on microstructure and mechanical properties of CP-Ti powder consolidations

Effects of various sintering methods such as spark plasma sintering (SPS), hot pressing (HP) and electric resistance sintering (ERS) on the microstructure and mechanical properties of commercial pure titanium (CP-Ti) powder consolidations with particle size of <147 μm, <74 μm and <43 μm were studied. The smaller particle powders are densified to proceed at a higher rate. Dense titanium with relative density up to 99% is found to take place at 850 °C under 30 MPa of SPS and HP condition. However, in case of ERS, CP-Ti powders were densified almost at 950 °C under 30 MPa. The microstructure of sintered titanium is composed of equiaxed grains at 850–950 °C. The yield strength of sintered body composed of <43 μm powder is 858 MPa by using SPS at 850 °C under 30 MPa. When there is a higher content of small particle, the higher yield strength value is obtained both by using SPS and HP. However, when ERS is introduced, the highest yield strength is 441 MPa at 950 °C under 30 MPa, which shows much lower values than those by SPS and HP methods. ERS method takes much less sintering time compared with SPS and HP. Nevertheless, higher sintering temperature results in lower strength and elongation because of brittle fracture.

Effect of particle size distribution on microstructure and mechanical properties of spark-plasma-sintered titanium from CP-Ti powders

The aim of this study was to determine the effect of particle size distribution on the microstructure and mechanical properties of spark-plasma-sintered titanium made from commercial pure titanium (CP-Ti) powders. The spark plasma sintering (SPS) of 100-mesh, 200-mesh, 325-mesh CP-Ti powders and mixtures thereof (100-mesh and 325-mesh powders mixed in weight ratios of 3:7, 5:5, and 7:3) was carried out in a flowing atmosphere of Ar + H2 gas at 800∼850°C under a pressure of 30 MPa. Dense titanium with a relative density of up to 99% was found to form for SPS conditions of over 850°C and 30 MPa. The sintered body showed a difference in sintered properties depending on the particle size of the powder: the smaller the particle size, the more rapid the densification, and in terms of the grain size of the sintered body, equiaxed grain of about 20∼40 µm in diameter was formed regardless of the particle size distribution of the powder. Regarding the hardness and tensile properties in the fully densified sintered body, smaller average particle sizes gave rise to higher values because of the increase in the content of interstitial solid solution and the formation of a homogeneous and fine-grained structure through the rapid densification process.

A new consumable anode material of titanium oxycarbonitride for the USTB titanium process

A single phase titanium oxycarbonitride TiC0.25O0.25N0.5 was prepared by sintering a homogenous mixture of TiO, TiC and TiN with a molar ratio of 1 : 1 : 2 by spark plasma sintering (SPS) at 1873 K. TiO0.25C0.25N0.5 was then used as the consumable anode for the USTB titanium process and the anode dissolution process was investigated by electrochemical methods. The results showed that TiO0.25C0.25N0.5 was electrochemically dissolved into Ti(2+) in the NaCl-KCl melts as determined by square-wave voltammetry analysis and simultaneously CO as well as N2 evolved in the anode as detected by mass spectroscopy. And TiO0.25C0.25N0.5 has exhibited a similar electron transfer resistance as TiC0.5O0.5 and TiN as measured by electrochemical impedance spectroscopy (EIS) analysis. By galvanostatic electrolysis, the cathode products were proved to be pure titanium powders. The results indicated that TiO0.25C0.25N0.5 is a suitable consumable anode for the USTB titanium process.

Densification Behavior of Different Metal Powders by Compression and Shear Combined Loading

Applying compression and shear combined loading to pure iron, pure titanium and stainless steel powders with different hardness, the densification effect by shear loading was compared. For all powder the large density improvement by shear loading was seen. The density increment by shear loading greatly depended on the density namely residual cavities before shear loading. Then the density increment by shear loading was large for high hardness powder on 700MPa. However, on 300MPa the density increment for stainless powder was smaller than for titanium powder although the density before shear loading was lowest. This was because the plastic deformation of high hardness powder was not easily promoted even by shear loading in low compression pressure. The densification effect by compression and shear combined loading depends on the density before giving shear loading and the ease of powder plastic deformation.

Development of Titanium Dental Implants Using Techniques of Powder Metallurgy

Titanium is an attractive material for dental and biomedical applications, because of high corrosion resistance, excellent biocompatibility and high mechanical strength combined with low density. However, the high reactivity of titanium in the liquid phase make it difficult to produce it by fusion, so a alternative is powder metallurgy (P/M) method. Powder Metallurgy has been used to manufacture porous implants. The presence of a porous surface is desirable because it improves the osteointegration increases the adhesion between the bone tissue and the implant, being favorable for transporting body fluid. This paper proposes to characterize the commercial pure titanium powder obtained by process of hydride-dehydride, obtain samples with adequate porosity by uniaxial pressing and vacuum sintering and evaluate the corrosion behavior of sintered titanium in Hank ́s solution. The results showed that the titanium powder of angular shape after uniaxial pressing of 400 MPa and sintered in vacuum at 1150 ° C, allowed obtaining samples with adequate surface porosity of around 17%. In potentiodynamic polarization curves revealed no typical behavior of passive metals but show low current density, that increasing corrosion resistance. Keywords: titanium implants, powder metallurgy, porosity and electrochemical behavior.

J0320303 低温焼結により作製されたチタン多孔質体のカプセルフリーHIP処理とその評価([J032-03]ポリマー・セラミックス・メタル多孔質材料の開発と応用(3),材料力学部門)

The low elastic modulus titanium alloy used for implant has been investigated, and the conflicting problem of strength and porosity has been challenged. Manufacturing of porous material by capsule-free hot isostatic pressing (HIP) can be expected for simultaneous control of porosity and mechanical strength. In this study, commercial pure titanium powders were sieved below 150μm and 106μm, and the sieved powders were compacted by hydraulic hand operated pressing machine. Then, the compacts were sintered by electric furnace under atmospheric pressure argon gas at 823K, and finally capsule-free HIPed under high-pressure argon gas (150MPa) at 1523K. Results showed that the HIPed compacts maintained pores sufficiently, and the character was affected by compaction load. The aspect of pore forming was, however, considered to be different in the surface and the inside.

Effect of plating on consolidation of commercially pure titanium powders

Blending of elemental powders is a common powder metallurgical processing route to produce titanium alloys designed to meet the required properties. An alternative to blending is coating the base titanium powders with specific metal ions by an electroless route to maximise advantages associated with homogeneous coating. In this work, Ni–P is being used as the coating material, to coat hydrogenated/dehydrogenated titanium powders. The particle size distribution of uncoated and coated powders was used to explain the change in tap density. A diametrical compression test was carried out to evaluate green strength of the particles when consolidated before and after coating.

Producing metallic titanium through electro-refining of titanium nitride anode

Titanium nitride (TiN) was used as consumable anode to produce metallic titanium in molten salts. The electrochemical dissolution of TiN was investigated. It was found that nitrogen (N2) was monitored at the anode during electrolysis. The titanium ion species was changed between Ti2+ and Ti3+ depending on the electrochemically dissolving potentials of TiN. Furthermore, the product on the cathode was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that pure titanium powders can be prepared by the TiN electro-refining in a molten salt bath.

Fabrication of Amorphous Ti&lt;sub&gt;63.7&lt;/sub&gt;Nb&lt;sub&gt;21.3&lt;/sub&gt;Zr&lt;sub&gt;4.5&lt;/sub&gt;Ta&lt;sub&gt;1.5&lt;/sub&gt;Fe&lt;sub&gt;9&lt;/sub&gt; Powder by Mechanical Alloying

Amorphous Ti63.7Nb21.3Zr4.5Ta1.5Fe9 powder has been designed and fabricated by mechanical alloying (MA) from a mixture of pure titanium and other elemental powders under a purified argon gas atmosphere in a stainless steel vial together with stainless steel balls. The amorphous alloy powders were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that a transform from a well-developed dislocation substructure to a mixed nanocrystalline plus amorphous structure occurs in Ti63.7Nb21.3Zr4.5Ta1.5Fe9 when milling time increases from 0 h to 15 h. Moreover, amorphous Ti63.7Nb21.3Zr4.5Ta1.5Fe9 powders were prepared after mechanical milling for 40 h. The results obtained are of the most significance for future work of densification of the milled powders.

Effect of heating on the properties of nano-crystalline titanium carbide during mechanical alloying process

In this research, the effect of heating on the mechanical alloying process for synthesizing of titanium carbide was investigated. Raw materials containing pure titanium and graphite powders were milled in different times and temperature. In order to detect phases and properties of synthesized materials X-ray diffraction was applied. Physical properties including density and specific surface area along with microstructure were studied. Results showed that heating can accelerate the mechanical alloying process. By increasing the temperature during milling, production mechanism of titanium carbide changed from self-propagating high-temperature synthesis to gradual model. Changes of density confirmed this phenomenon too. Increasing the milling time leads to particle size and crystal of synthesized titanium carbides became finer down to nanometer scale. Because of higher effective time span of produced titanium carbide, increasing the temperature produces finer particle sizes of powders in similar milling time.

S041023 酸素固溶強化純チタン粉末材の強化機構([S041-02]粉末成形とその評価(2))

In-process solid solution of oxygen atoms into pure titanium (Ti) powder via heat treatment under controlled atmosphere was employed to prepare powder metallurgy (P/M) extruded Ti materials. They showed extremely high tensile strength and elongation compared to P/M pure Ti material with no oxygen solid solution. The experimental data of yield stress increment corresponded well to the calculation results by using Labusch model generally used for analysis of the solid solute strengthening behavior. It was concluded that the main strengthening mechanism of P/M pure Ti materials was oxygen solid solution into Ti matrix.

Compaction of Commercially Pure Titanium Powder by Friction Powder Compaction Process

A new friction powder compaction (FPC) process is introduced for compacting commercially pure titanium powder. The FPC process is very simple and energy-efficient since it requires only a rotating tool plunged into an aluminum plate with a hole filled with titanium powder, and no external heat source is necessary. The sintering of the powder is mainly achieved by the friction heat and pressing load generated by the rotating tool in the aluminum plate and powder. The microstructure and Vickers hardness of the compacted titanium powder were investigated. It was shown that titanium powder was satisfactorily compacted by the FPC process. [doi:10.2320/matertrans.MC201208]

Comparison of titanium soaked in 5 M NaOH or 5 M KOH solutions

Commercially pure titanium plates/coupons and pure titanium powders were soaked for 24h in 5M NaOH and 5M KOH solutions, under identical conditions, over the temperature range of 37° to 90°C. Wettability of the surfaces of alkali-treated cpTi coupons was studied by using contact angle goniometry. cpTi coupons soaked in 5M NaOH or 5M KOH solutions were found to have hydrophilic surfaces. Hydrous alkali titanate nanofibers and nanotubes were identified with SEM/EDXS and grazing incidence XRD. Surface areas of Ti powders increased >50–220 times, depending on the treatment, when soaked in the above solutions. A solution was developed to coat amorphous calcium phosphate, instead of hydroxyapatite, on Ti coupon surfaces. In vitro cell culture tests were performed with osteoblast-like cells on the alkali-treated samples.

Characterisation of electroless nickel plated titanium powder

In this study, pure titanium powder with an average size of 20 μm was treated by electroless nickel plating to obtain titanium–nickel composite/duplex powder. Two plating procedures were applied; continuous short period (CSP) and discontinuous long period (DLP) processes. The plated titanium powder particles as well as unplated ones were characterised by energy dispersive spectrometry (EDS), scanning electron microscopy (SEM), particle size analysis and X-ray mapping analysis methods. The nickel plated titanium powder was sprayed on the steel substrate by atmospheric plasma spray technique. Furthermore, the mixed titanium–nickel powder was also sprayed. The morphology of sprayed powders was compared with each other. It was found that nickel forms fine dispersed nodules on the surface of titanium powder particles in the CSP process, whereas it appeared as homogeneous layers on the surface of all the particles in the DLP process. Also, it was found that the mass deposited on the powder increased with the plating period. The sprayed nickel plated powder showed better microstructure than the sprayed nickel mixed one.

Characterization of titanium powder: Microscopic views and macroscopic flow

Powder metallurgy is a very popular and cost effective process due to improvements in powder availability and the ability to produce a part close to the desired net shape. With the introduction of the Armstrong Process®, which produces commercially pure titanium powder, it is necessary to understand the flowability characteristics of the irregular particles produced. This paper reports the physical properties of the raw powder and a characterization of the inter-particle forces present in the poly-disperse size mixture. The titanium powder size distribution and particle morphology are determined using sieve analysis and quantitative SEM image analysis, respectively. The results demonstrate that attempts to improve the shape of the particles simply yield smaller irregular shaped particles, but with a high concentration (≈20%) of extremely fine particles that are less than 45μm. However, the microstructure of all particle sizes remains consistent with an irregular outline and a porous interior, much like coral. The inter-particle force properties are approximated by measuring the dynamic angle of repose within a rotating tumbler. Tumbler dimensions and rotation rate of the system are non-dimensionalized via the Froude number, which relates input energy to gravity driving the flow. The results confirm the increase of the angle of repose with increasing Froude number. However, the high concentration of very fine particles in mixtures that are processed to generate more round titanium powder are found to be a detriment to uniform, repeatable flow that is necessary in manufacturing processes. The overall conclusion is that narrower size ranges of titanium powders produced by the Armstrong Process® are necessary to provide useful source materials in powder metallurgy applications.

Enhanced photocatalytic properties of ultra-long nanofiber synthesized from pure titanium powders

Using Ti powder as reagent, ultra-long TiO2 nanofibers were prepared via hydrothermal method in NaOH solution. The samples were characterized respectively by means of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), and X-ray diffraction (XRD). The diameter and the length of the ultra-long TiO2 nanofiber were ∼100 nm and >200 μm, respectively. The ultra-long TiO2 nanofibers were anatase after heat treatment at 450 °C for 1 h. Moreover, the optical properties of the products were investigated by UV-visible light absorption spectrum. Furthermore, methyl orange was used as a target molecule to estimate the photocatalytic activity of the specimens. Under the same testing conditions, the photocatalytic activity of the ultra-long TiO2 nanofibers was higher than that of P25. Direct electrical pathway and improved light-harvesting efficiency were crucial for the superior photocatalytic activity of the ultra-long TiO2 nanofibers.

Cespace: sistema de fusión intersomática cervical: Estudio preliminar en 104 casos (120 implantes)

Cespace is a cervical implant designed to obtain intervertebral fusion without bone grafting. The implant is built in titanium and coated with plasmapore (a sort of pure titanium powder). Bone growing through titanium microstructure is induced by the plasmapore, and fusion is progressively obtained once this boneinduction is completed. From January 2002 to December 2008 we operated upon 104 patients employing this implant at one or two cervical spine levels. The more frequent condition was radiculopathy caused by disc herniation or spondilosis (N= 85; 81.7%), followed by mielopathy (N=13; 12.5%). Six cases (5.7%) corresponded to cervical fractures or dislocations. In these latter ones Cespace was implanted as a method of spinal stabilization combined with Caspar plates, avoiding bone grafting. The total number of Cespace implants placed was 120. Clinical results were good in 85.5% of patients. Primary stability was obtained in all cases. Secondary stability (fusion) was evident after 1 to 2 years in all cases, confirming the bone-induction capability of plasmapore without bone grafting. No specific implant complications (pseudoartroses, settling, instability, etc) were registered. We conclude that radical microdiscectomy and Cespace box implant constitutes a good procedure for the treatment of cervical radiculopathy or mielopathy caused by disc herniation or spondylosis, avoiding bone grafting and providing high rates of vertebral fusion. In some cervical fractures associated to instability, Cespace can be used as a reliable substitute of intervertebral bone grafting in combination with anterior plate fixation.

Innovative consolidation of titanium and titanium alloy powders by direct rolling

R&D efforts at CSIRO, Australia, into the production of ‘lower cost’ titanium powders are complemented by a strong, downstream PM programme. One of these efforts has focused on the direct powder rolling of commercially pure (cp) titanium powder with a view to the continuous production of fully dense strip. Considerable research is also being undertaken to produce titanium alloy strip, initially from the Ti–6Al–4V alloy, using this process. An experimental design approach has been employed to establish key parameters, maximise the process window and meet property specifications. Demonstration of a proof-of-system at pilot scale is well advanced and the focus is now shifting to seeking industrial engagement with a view to collaboration, technology transfer and commercialisation of the technology. The current status of the technology is surveyed including aspects of the associated market trends and commercial feasibility.

Warm Compacting Behavior of Pure Titanium Powders

Warm compacting behaviors of pure titanium powders were studied. The results show that warm compaction can be applied to titanium powders. The green densities obtained through warm compaction are generally higher than obtained through cold compaction at the same pressure. The optimal warm compacting temperature is about 140 . At the compacting pressure of 500 Mpa, the ejection force of titanium powders through warm compaction is 32.4% lower than through cold compaction. At the same pressure, the effective compression force through warm compaction is bigger than one through cold compaction. In addition, the densification mechanism of warm compaction was discussed.