Papers by Keyword: Titanium Powder

Abstract: The method of powder metallurgy for the manufacture of titanium products has the advantages of low cost of raw titanium, short technological process, low energy consumption, and less equipment investments. This allows to significantly reduce the total costs. The method is a potential technology to manufacture inexpensive products from titanium alloys. Due to its high strength, low specific weight and high corrosion resistance, titanium is widely used in aerospace and automotive industries and biomedicine. Among various applications of titanium, tube- and disc-shaped products from titanium powder are essential. The paper presents the results on the investigation of products made of titanium powder by the method of magneto-pulse pressing. Titanium powders with a particle size of 160-1000 mm produced by grinding titanium sponge and its powder compositions were used in the investigation. Investigation results on microstructure and porosity are also discussed. The mean porosity of the samples after sintering was 25-28% for products of 4-6 mm thick. With increasing thickness, the porosity increases to 35% and more, while it was non-uniform both over the cross-section of a tube-shaped product and along its length. The outer surface of the product was found to have a looser microstructure. This can be explained by the application of an intermediate fusible layer to the inner wall of the shell, which makes easier the removal of the shall after pressing. The studies generally confirm the possibility tof using the magneto-pulse pressing of titanium powders in shells to manufacturesmall product batches.

Abstract: The main aim of this work is to obtain a compact spherical titanium powder by the metallo-thermic reduction. The feedstock is TiO₂ (rutile), and aluminum shavings are used as the reducing metal. In the reduction process granules of titanium powder and corundum were obtained. For cleaning titanium powder from corundum, various alkaline and acid processing methods were used. When using the alkaline treatment method of the powder, obtained after reduction of sand and floury rutile by aluminum shavings, its weight decrease was 36-37%.

Abstract: In this work, a commercially pure titanium powder has been consolidated using the Electrical Resistance Sintering (ERS) process. This technique consists in the consolidation of a powder mass by the simultaneous application of pressure (80 MPa, in this work) and heating caused by the passage of a high intensity (3.5-6.0 kA, in this case) and low voltage current (lower than 10 V), during short dwelling times (0.8-1.6 s, in this work). The resulting compacts have been mechanically characterised by measuring their microhardness distribution. The results obtained are compared with the corresponding values of compacts prepared with the same powders following the conventional P/M route of cold pressing and furnace sintering. The results of some simulations are provided to give information about the temperatures reached inside the compacts during the electrical consolidation process.

Abstract: The transformations of the solid and liquid phases at high energy planetary ball milling of heptane together with titanium powder were investigated. The sequence of structural heptane transformations using UV-and FT-IR spectroscopy was investigated. Phase constitutions of ball milled titanium powders were studied by X-ray diffraction. It is shown that mechanically induced destruction of heptane occurs by the mechanism of catalytic cracking. The main solid products of the mechanosynthesis were hexagonal (HCP) and cubic (FCC) titanium carbohydrides. Evolution of lattice parameters, crystallite sizes, and micro-stresses of the solid phases during ball milling as a function of the ball milling time have been discussed.

Abstract: The present work deals with the investigation of the transformations of the solid and liquid phases at high energy planetary ball milling of toluene together with titanium powder. The sequence of structural toluene transformations using FT-IR spectroscopy was investigated. Phase constitutions and morphology of ball milled titanium powders were studied by X-ray diffraction and scanning electron microscopy. It is shown that mechanically induced destruction of toluene occurs by the mechanism of catalytic cracking. During ball milling, concentration of aromatic hydrocarbons in the liquid phase decreases, at the same time the content of alkenes, cycloalkanes, and isoalkanes increases. The main solid products of the mechanosynthesis were cubic and hexagonal titanium carbo-hydrides.Evolution of lattice parameters, crystallites sizes, and micro-stresses of the solid phases during ball milling as a function of the mechanical energy dose have been discussed.

Abstract: As the adoption of components fabricated via titanium powder metallurgy (PM) techniques becomes more prevalent, and projected to increase at a substantial rate over the next decade, especially in the field of additive manufacturing (AM), there is a necessity to increase titanium powder production capacity from the current annual level of ca. 6000 tonnes per annum. At present a well-documented barrier restricting this widespread implementation, is the inherently high cost of the feedstock, an issue which to date has been neglected to some degree, at the expense of developing the individual powder metallurgy routes. The scope of this overview therefore is to provide an insight of both established and novel methods of titanium powder production, as potential opportunities to satisfy this growing demand. Particular emphasis will focus on Metalysis, a company founded to commercialize an innovative electrochemical approach for the synthesis of metals and alloys from their respective oxides, where the ability to generate titanium eloquently demonstrates the extent of its capabilities.The patented Metalysis technology, exploiting the FFC^® Cambridge process, lends itself to producing alloys and intermetallics, where Ti-6Al-4V provides a prime example of this. Furthermore, as electrolysis occurs solely in the solid state, issues pertaining to segregation due to dissimilar densities and melting points are avoided. It is possible to tailor both the average particle diameter and size distribution of the product targeted powder metallurgy (PM) applications, based upon appropriate selection of the feed. The attraction of this strategy is that the steps associated with conventional metal powder synthesis are circumvented, resulting in a significant cost reduction. Moreover it has recently been revealed that titanium can be produced directly from naturally occurring ore (beach sand) and synthetic rutile, with the ensuing product presenting itself as an inexpensive and abundant feedstock for additive manufacturing (AM). This represents a paradigm shift in the availability of consumables for the 3D printing market.

Abstract: The TiROTM process has been developed at CSIRO for the continuous direct production of Ti powder. The process has two main steps; a reaction step where the Ti is produced as very fine particles dispersed in larger particles of magnesium chloride. The MgCl₂ is separated from the Ti powder in a continuous vacuum distillation unit. The Ti product from this unit comprises a lightly sintered “biscuit” of Ti particles that can be broken up into individual particles powder with a d₅₀ around 200 μm. These particles have a unique morphology which is a function of the process.For many powder metallurgical applications TiROTM powder will require further processing to tailor its morphology for the specific application. A small sample of Ti strip has been produced from ring milled TiROTM powder by a CSIRO patented combination of direct powder rolling (DPR) followed by hot roll densification (HRD). The Ti strip was annealed and characterised in terms of microstructure and chemistry.A powder manipulation technology (PMT) has been developed to modify TIROTM particulates without the need of more expensive hydride-dehydride (HDH) or gas atomization routes to improve density, flowability, size, distribution and shape for cold spray and additive manufacturing applications.

Abstract: The paper captures the effect of structure and the applicability of compaction models using the cold compaction of a TiH₂-SS316L composite powder prepared by high energy mechanical milling. The composite blend was cold pressed uniaxially to pressures of up to 1250MPa. The compressibility of the composite blend was evaluated by fitting the experimental data to the most commonly used compaction models of Heckel, the Kawakita-Lüdde, the Cooper-Eaton, the Ge, and the Panelli-Filho compaction equations. Among the models, the Kawakita-Lüdde and Cooper-Eaton models fitted the experimental data very well with a good correlation (the correlation coefficient greater than 0.99) throughout the entire pressure range under investigation. The nature and mechanisms responsible for the densification during cold compaction are discussed. The Heckel, Ge, Panelli-Filho, and Cooper-Eaton model analysis showed that the dominant compaction mechanisms for composite blend were rearrangement of particles followed by elastic and plastic deformation. The results are discussed by way of a comprehensive model intercomparison study of the cold compaction behaviour using existing models.

Abstract: Direct powder rolling (DPR)/roll compaction has been labelled a complex and sample sensitive process. As such the design of the instrument and the determination of the optimal processing conditions for a given feed are very challenging. The challenge is attributed to a wide range of operating parameters and material properties. Several theoretical models can be used to evaluate the interaction of the different parameters and properties and how their changes affect the rolling process. In this study, the Johanson theory was used to determine the rolling parameters of titanium powder. Preliminary results of the nip angle, nip pressures and maximum horizontal pressures of the mill for the powder rolled on a 55mm diameter roll with roll gap sizes of 0.175, 0.15 and 0.05 mm were obtained. The results were found to be acceptable for the nip angle estimation, however improvement on predicting the maximum horizontal pressure is required.

Abstract: In order to reliably design and operate different powder processes, an understanding of the dynamic flow, shear and bulk properties of powders is required. Generally, powders are evaluated by several techniques that determine their flow, shear and bulk properties. The techniques can include compression tests, shear tests, angle of repose, flow of powder in a funnel, tapped density and many others. In order to minimize the number of instruments required to characterise the powder and eliminate operator error, automated powder rheometers that can do most of the required tests have been developed. The FT4 powder rheometer is one of these and has found widespread use in the pharmaceutical industry. In this study, the FT4 powder rheometer was used to characterise two metallic titanium powders with different particle sizes, namely CSIR Ti-45μm (Fine Powder) and CSIR Ti +45-180μm (Coarse Powder). Their particle size, particle size distribution, bulk densities, compressibility, cohesion, flowability index, effective angle of internal friction and wall friction angle were determined. Preliminary results of the study indicated that fine powder had a lower bulk density, was more compressible and more cohesive than the coarse powder. The fine powder had a lower flowability index compared to the coarse powder for both the Jenike and Peschl classification. The varying degrees of cohesion of these powders were confirmed by the cohesion values that were higher for the fine powder. The fine powder had a lower angle of internal friction but higher wall friction angle compared to the coarse powder.