Titanium Sponge Research Articles

Aggregation-Growth and Densification Behavior of Titanium Particles in Molten Mg-MgCl2 System.

In this work, the preparation of titanium sponge by magnesium thermal method is regarded as the liquid-phase sintering process of titanium, and powder-metallurgy sintering technology is utilized to simulate the aggregation-growth and densification behavior of titanium particles in a high-temperature liquid medium (the molten Mg-MgCl2 system). It was found that compared with MgCl2, Mg has better high-temperature wettability and reduction effect, which promotes titanium particles to form a sponge titanium skeleton at lower temperature. The aggregation degree of titanium particles and the densification degree of a sponge titanium skeleton can be improved by increasing the temperature and the relative content of Mg in the melting medium. The kinetics study shows that with the increase in temperature, the porosity of the titanium particle aggregates and the sponge titanium skeleton decreases, and their density growth rate increases. With the extension of time, the aggregation degree of titanium particles and the densification degree of sponge titanium gradually increase. This work provides a theoretical reference for controlling the density of titanium sponge in industry.

Research Progress of Preparing Titanium Alloy By Molten Salt Method

Titanium alloy has excellent characteristics that cannot be compared with other metals such as light specific gravity, high specific strength, wide applicable temperature range, corrosion resistance, and hydrogen storage. The traditional titanium alloy smelting process is mainly based on titanium sponge as raw material, which has a long process, high energy consumption, heavy pollution, and other problems, which seriously restricts the sustainable development of titanium alloy in the world. The common methods of preparing titanium alloy are alloy melting, metal thermal reduction, powder metallurgy, and the gradually emerging molten salt electrolysis. Among them, molten salt electrolysis is recognized as the most promising method to replace the traditional titanium alloy production process, and certain achievements have been made in recent years in terms of both process and basic theory research. In this paper, the common processes of titanium alloy preparation by molten salt electrolysis at home and abroad, such as molten salt electrolytic co-deposition method, cathodic alloying method and liquid cathode method, new FFC method, and its derived SOM method, etc., will be summarized systematically, and the future research will be put forward.

The Study of Radioactive Contaminations within the Production Processes of Metal Titanium for Low-Background Experiments.

Ultra-low-radioactivity titanium alloys are promising materials for the manufacture of low-background detectors which are being developed for experiments in astroparticle physics and neutrino astrophysics. Structural titanium is manufactured on an industrial scale from titanium sponge. The ultra-low-background titanium sponge can be produced on an industrial scale with a contamination level of less than 1 mBq/kg of uranium and thorium isotopes. The pathways of contaminants during the industrial production of structural titanium were analyzed. The measurements were carried out using two methods: inductively coupled plasma mass spectroscopy (ICP-MS) and gamma spectroscopy using high-purity germanium detectors (HPGes). It was shown that the level of contamination with radioactive impurities does not increase during the remelting of titanium sponge and mechanical processing. We examined titanium alloy samples obtained at different stages of titanium production, namely an electrode compaction, a vacuum arc remelting with a consumable electrode, and a cold rolling of titanium sheets. We found out that all doped samples that were studied would be a source of uranium and thorium contamination in the final titanium alloys. It has been established that the only product allowed obtaining ultra-low-background titanium was the commercial VT1-00 alloy, which is manufactured without master alloys addition. The master alloys in the titanium production process were found cause U/Th contamination.

Porous Ti3AlC2 MAX phase enables efficient synthesis of Ti3C2Tx MXene

AbstractMXenes, a large family of two‐dimensional carbides and/or nitrides, are among the most studied materials worldwide due to their great diversity of structures and compositions. Their unique properties find use in several applications. Typically, they are manufactured by selective wet‐chemical etching of layered MAX phase ceramics, which are produced nowadays primarily for MXene synthesis. However, the synthesis of MAX phases has not been changed since the time of their use in structural and high‐temperature applications, and it has not been optimized for MXene manufacturing. The main purpose of this study is to develop a porous Ti3AlC2 MAX phase that can be easily ground into individual grains without time‐consuming, harsh, and tedious crushing and milling steps. Moreover, we also demonstrate the synthesis of highly porous Ti3AlC2 from an inexpensive titanium sponge instead of a highly pure titanium powder and explain the mechanisms of reaction sintering and formation of porous MAX phase. MXene obtained from this MAX phase, Ti3C2Tx, shows larger flake size and higher electrical conductivity in thin films, compared to the materials produced from the costly fine titanium powder. The proposed approach may apply to the synthesis of other MAX phases as well.

Development of deoxidation process for off-grade titanium sponge using magnesium metal with wire mesh strainer type of crucible

In this study, the deoxidation process for off-grade titanium (Ti) sponge using magnesium (Mg) metal with a wire mesh strainer type of crucible was developed. Ti hydride (TiH2) feedstock, which was prepared by hydrogenating off-grade Ti sponge, was deoxidized using Mg in a molten magnesium chloride–potassium chloride salt at 933 K under an argon and 20% hydrogen (H2) mixed gas atmosphere. After deoxidation, the residual Mg-containing salt was separated in situ from the crucible to investigate the feasibility of minimizing salt loss during the leaching and production of pure TiH2. The results showed that the presence of residual Mg-containing salt inside the crucible strongly influenced whether a mixture of Ti and TiH2 or pure TiH2 was produced. When the salt was not sufficiently separated, a mixture of Ti and TiH2 was obtained and its oxygen (O) concentration was 0.121 mass% under certain conditions. Meanwhile, pure TiH2 was obtained by increasing the H2 gas flow rate during deoxidation. Therefore, these results demonstrate that the decrease of O concentration to below 0.180 mass% and the minimal loss of the salt are feasible.

Thin layer modeling the drying kinetics of titanium slag under microwave-assisted drying

High moisture content of titanium slag renders it unsuitable for producing titanium dioxide chloride and titanium sponge in industrial settings. Microwave heating were employed to investigate the impact of initial mass, microwave heating power, and initial water content on the drying process of titanium slag. The results demonstrated positive correlation between the average drying rate and these three variables. Titanium slag weighing 30 g, subjected to microwave heating power of 400 W, and possessing water content of 15 %, was fitted using Page, Wang, Singh, Two-term exponential, and Quadratic models. The findings unequivocally supported the superiority of the Page model in elucidating the microwave drying, which can also be extended to encompass other experimental parameters. By utilizing Fick's second law, the effective diffusion coefficient was computed, revealing an increase followed by subsequent decrease concerning initial mass, while increasing in tandem with microwave heating power and initial water content. Correlation analysis between activation energy and microwave power disclosed an activation energy of −9.94 g/W for the drying of titanium slag. This research provides a valuable reference for the drying of materials, facilitating the more efficient employment of microwave technology in drying metallurgical and chemical raw materials.

Developments of Cost Affordable Titanium Alloys in Japan

Titanium and its alloys are the 5th most common metallic materials used world wide but the markets volume of titanium materials, is difficult to expand due to associated production costs, and the decrease of those costs are critical in order to expand their markets. A possible option is the alloy design, i.e. using low price alloying element, such as iron, chromium, manganese and oxygen, and the selection of other raw materials, i.e. grade of sponge titanium. In beta titanium alloy, Ti-Mo system alloy using ferro-molybdeum was developed by USA company or Ti-Cr-Fe-Al beta alloy were also developed by Japan company. In this paper, those developed alloys were explained. Furthermore, substitution of Ti-10V-2Fe-3Al near beta alloy, presenters are studying about Ti-Mn-Fe-Al alloy.

Investigation of the Microstructure of Porous Tube-Shaped Elements Made of Ti-Powder Materials

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.

Influence of various titanium-containing additives on the modification efficiency of aluminum–silicon eutectic alloy

This study investigates the impact of titanium addition to the eutectic silumin AK12 melt, considering various methods of addition. The research results encompass the sole introduction of titanium (at a calculated amount of 0.1 wt.%) through different forms/methods, such as the Al–4%Ti ligature, TiO2 oxide, K2TiF6 salt, and Ti sponge. Additionally, the study explores the combined addition of titanium and a standard flux (comprising 62.5 % NaCl + 12.5 % KCl + 25 % NaF). The research involved qualitative and quantitative analyses of macro- and microstructures, spectral analysis data, and mechanical properties (tensile strength and relative elongation) of the alloys. The findings highlight that titanium has a positive influence on the structure of eutectic silumin, with the most effective results achieved when combined with the standard flux. However, the efficiency of silumin modification with titanium varies depending on the method of addition. Specifically, the introduction of titanium in the form of K2TiF6 fluoride salt, Al–4%Ti ligature, and titanium sponge positively affected macro grain refinement, reduced the spacing between the secondary dendrite arms of the solid solution (α-Al), and enhanced the dispersion of eutectic silicon. The most promising approach for complex silumin modification involves the joint introduction of titanium-containing substances and a sodium salt-based flux. This combination has a multifaceted impact on the silumin structure, leading to the simultaneous modification of various structural components in aluminum–silicon alloys. Depending on the type of titanium-containing substance, when processed alongside flux, the alloy achieves a relative elongation ranging from 9.7 % to 11.1 %, exceeding the same parameter for the unmodified alloy by more than 4 times and surpassing the sodium-modified alloy's relative elongation by 17–37 %. Furthermore, the ultimate strength reaches levels of 171–193 MPa, representing a 22–38 % improvement compared to the unmodified alloy and a 7–21 % increase compared to the sodium-modified alloy.

Thin-film evaporation characteristics of molten magnesium and magnesium chloride in a microchannel of titanium sponge

Thin-film evaporation characteristics of molten magnesium and magnesium chloride in a microchannel of titanium sponge

Preparation of low-oxygen titanium powder by magnesiothermic reduction of TiO2 in KCl–MgCl2–YCl3 molten salt

The Kroll process is currently the only effective method in industry to produce sponge titanium with a low-oxygen concentration (500 ppm). However, it has several limitations, such as a long processing time, low efficiency, and high energy consumption, resulting in the high production cost of titanium. To reduce the production cost, a method to prepare low-oxygen titanium powder by magnesiothermic reduction of TiO2 in KCl–MgCl2–YCl3 molten salt was designed. The thermodynamic calculation results showed that it was feasible to prepare titanium powder by the magnesiothermic reduction of TiO2 at 1073, 1173, and 1273 K. In addition, the deoxidation limits of Mg under Mg/MgCl2/YCl3/YOCl equilibrium were 3, 12, and 38 ppm at 1073, 1173, and 1273 K, respectively. The experimental results showed that titanium powder with a high oxygen concentration of approximately 10,000 ppm was obtained when the reduction was conducted in KCl–MgCl2 molten salt (i.e., the activity of YCl3 (aYCl3) was 0). Low-oxygen titanium powder was prepared with the addition of YCl3 in the molten salt and formed yttrium oxychloride (YOCl) (TiO2 (s) + 2Mg (l) + 2YCl3 (l) = Ti (s) + 2MgCl2 (l) + 2YOCl (s)). Moreover, at 1173 K, when the activity of YCl3 (aYCl3) was 1, titanium powder with an oxygen concentration as low as 150 ppm was obtained. Based on these results, a novel process for preparing low-oxygen titanium powder was designed. The proposed process is fast and highly efficient, and its future application in industry is anticipated.

CREATION OF SPECIAL CONSTRUCTION MATERIAL USING THE ROLLING METHOD OF ASYMMETRICAL PACKAGES FOR DUAL-PURPOSE PRODUCTS

Purpose. The object of research in this work was the creation of a bimetallic material with increased mechanical and operational properties by rolling asymmetric packages. According to the preliminary results of the structure and properties research, the optimal compositions of the base and cladding layer of the bimetallic workpiece with the smallest difference in thermal expansion coefficients were selected. With the help of asymmetric rolling of base packages – steel 14Х17Н13КМБх + cladding layer-steel 03Х17Н3Г9МБДЮч, a bimetallic workpiece was made, which had low stresses in the welded seam and the zone of thermal influence, unlike the package 14Х17Н13КМБх + 10ХФТБх. Therefore, no grooving and thermal cracks were observed in the bimetal samples during the magneithermal production of spongy titanium. The inflow of nickel into spongy titanium from the surface of the plating layer during the recovery process did not exceed 0.004 % by mass. in the first five blocks of titanium since the beginning of operation.
 Research methods. Metallographic, durometric, dilatometric.
 Results. With the help of dilatometric research, the coefficients of thermal expansion of samples of base steels – 14Х17Н13КМБх, and steels of the cladding layer – 10ХФТБх and 03Х17Н3Г9МБДЮч were obtained. As a result of research close to production conditions, a bimetallic workpiece was obtained, which is not subject to gouging, is crack-resistant and does not cause nickel to flow into the titanium sponge.
 Scientific novelty. On the basis of experimental data, the development of destruction of the inner surface of the reactors of the magnetothermal process for the production of sponge titanium, which is subjected to temperature, mechanical load and periodic contact with titanium tetrachloride, liquid magnesium and magnesium chloride, which leads to grooving, the appearance of cracks in the reactor and the inflow of nickel into the titanium sponge, has been established. It is shown that in order to eliminate these undesirable phenomena, it is necessary to use a bimetallic material of different chemical composition with similar structure and physical and mechanical properties: coefficient of thermal expansion, hardness and strength limit.
 Practical value. On the basis of research results, the chemical composition of the base – steel 14Х17Н13КМБч, cladding layer – steel 03Х17Н3Г9МБДЮч and the mode of hot deformation were developed, which made it possible to obtain the necessary structure, physico-mechanical and service properties.

Аналитическая модель равноканального углового прессования титановой губки

Introduction. The use of equal-channel angular pressing (ECAP) of metal powder makes it possible to obtain practically non-porous blanks with high hardness, with a high level of accumulated deformation and with the formation of an ultra-fine-grained structure. A relevant issue for the study of the semi-continuous ECAP process remains a reliable assessment of the energy-power parameters of the process and the prediction of the porosity of compressed materials. This, in turn, is due to the need to develop sufficiently accurate, reliable and simple mathematical models for practical application. The purpose of the work is to develop an analytical model of the process of equal-channel angular pressing of porous material. Powdered screening of spongy titanium of the TG-100 brand was selected as a model of the material for the study. The object of the study is the process of semi-continuous equal-channel angular pressing of axisymmetric porous briquette of titanium sponge in the channel of the mold. It is assumed that the ECAP uses a punch to create back pressure. For the solution, a process scheme, a statically permissible load scheme on a layer of intense deformation and a kinematically permissible flow scheme of a plastically compressible medium in a layer are determined. A system of equations is constructed in accordance with the accepted schemes. The equation power balance is applied. The analytical equation is solved by the method of successive approximations. Finite element simulation of the porous titanium ECAP process was carried out at the angles of intersection of the mold channels at 45°, 50°, 55° and 60°. Results and Discussion. The porosity of the blank is determined at different stages of the ECAP process. A diagram of the change in pressure on the punch using the analytical solution and finite element simulation is obtained. It is revealed that the results of the analytical solution are consistent with the data of the finite element simulation. The highest stress level occurs in the process of equal-channel angular pressing at α = 45°, however, the distribution of relative density over the cross section is most uniform. The maximum value of the pressure on the working punch decreases with an increase in the angle α. Rational technological parameters of pressing porous blanks should provide the maximum permissible pressure on the deforming tool. From this condition, in each specific ECAP process, it is possible to determine the optimal angle value from the analytical solution.

Strong and ductile titanium–oxygen–iron alloys by additive manufacturing

Titanium alloys are advanced lightweight materials, indispensable for many critical applications1,2. The mainstay of the titanium industry is the α–β titanium alloys, which are formulated through alloying additions that stabilize the α and β phases3–5. Our work focuses on harnessing two of the most powerful stabilizing elements and strengtheners for α–β titanium alloys, oxygen and iron1–5, which are readily abundant. However, the embrittling effect of oxygen6,7, described colloquially as ‘the kryptonite to titanium’8, and the microsegregation of iron9 have hindered their combination for the development of strong and ductile α–β titanium–oxygen–iron alloys. Here we integrate alloy design with additive manufacturing (AM) process design to demonstrate a series of titanium–oxygen–iron compositions that exhibit outstanding tensile properties. We explain the atomic-scale origins of these properties using various characterization techniques. The abundance of oxygen and iron and the process simplicity for net-shape or near-net-shape manufacturing by AM make these α–β titanium–oxygen–iron alloys attractive for a diverse range of applications. Furthermore, they offer promise for industrial-scale use of off-grade sponge titanium or sponge titanium–oxygen–iron10,11, an industrial waste product at present. The economic and environmental potential to reduce the carbon footprint of the energy-intensive sponge titanium production12 is substantial.

CFD Simulation of Convection in a Reactor for the Production of Titanium Sponge by the Kroll Method

In this study, numerical simulations are performed for convective flow in a titanium reduction reactor under both unheated and heated conditions. The VOF multiphase flow model was used for the simulation, using a total of 986,521 hexahedral structured meshes and considering turbulence using LES (Large Eddy Simulation). The titanium reactor contains liquid magnesium at a temperature of 1123K. Magnesium chloride was added to the charging port at a rate of 5.6 × 10−6 m/s. In this process, the strong exothermic chemical reaction on the surface of the magnesium solution and the heating of the reactor cause strong temperature gradients, and these temperature gradients lead to strong convection inside the reactor. As the reaction progresses, the titanium sponge gradually accumulates at the bottom of the reactor, and the density of magnesium chloride precipitates close to magnesium chloride. The precipitation process of magnesium chloride in a titanium reduction reactor was numerically simulated by using the three-dimensional unsteady state method. The results show that convection causes magnesium chloride to precipitate as a droplet in the form of a vortex, and the transient velocity of the settling process reaches the maximum near the reactor interface. Simultaneously, changing the heating state can affect the flow structure of the reactor and create favorable conditions for the reaction.

Intragranular nanocomposite powders as building blocks for ceramic nanocomposites

AbstractA powder‐based bottom‐up processing scheme is introduced for the production of ceramic nanocomposites. Internal displacement reactions between solid solution powders and metallic reactants proceeding via gaseous intermediates are utilized to generate nanostructured building blocks for the synthesis of ceramic nanocomposites. Subsequent rapid sintering results in ceramic nanocomposites, whose microstructures are inherited from the building blocks. This processing scheme is demonstrated for the production of titanium carbide nanocomposites featuring up to 28 wt.% intragranular tungsten inclusions derived from titanium‐tungsten mixed carbide powders. Heat treatment of mixed carbide powders in evacuated ampoules containing titanium sponge and iodine at 1000°C for 24 h resulted in nanocomposite powders featuring tungsten precipitates within titanium carbide grains that were subsequently consolidated via spark plasma sintering at 1300°C for 10 min to produce titanium carbide/metallic tungsten nanocomposites. Transformation of mixed titanium–tungsten carbide powders to titanium carbide/metallic tungsten nanocomposite powders was analyzed via X‐ray diffraction. Electron microscopy observations of microstructures pre‐ and post‐ sintering showed that the intragranular character of nanocomposite powders can be retained in sintered ceramic nanocomposites. The building block approach demonstrated in this work represents an improved method to make ceramic nanocomposites with majority intragranular character.

Material Flows and Waste Management of Titanium Products in China from 2005 to 2020.

The online version contains supplementary material available at 10.1007/s40831-023-00667-4.

Модель формування пористості брикетів губчастого титану на стадії спікання

This article examines the peculiarities of the formation of interparticle connections in porous products based on titanium powders using sponge titanium as an example, which are used in the aviation industry and airfield management. The developed model is based on the results of a previous study, where the structure of cuboctahedral and inverse cuboctahedral clusters of packing spherical powder particles was determined at the most dense packing. During the study, a model of the fusion of particles at the points of pressing deformation due to recrystallization under the influence of high temperatures in a vacuum was developed. 4 main stages of powder briquette sintering were considered, and a mathematical model was developed for each of them. Thus, the stage of liquid evaporation is considered from the viewpoint of the cavitation effect of boiling on the surface of particles and boiling of plasticizers. Euler's film boiling formula was used to describe the forces acting on the particle surface; Tolubinsky's formula was used for bubble boiling; convective heat exchange was considered part of the final stage of sintering. The stage of the formation of metallic bonds is modeled on the basis of the results of practical studies in the REV 5.5 furnace, recrystallization based on differential scanning colorimetry on the NETZSCH STA 449F1 Proteus device, and determining the change in grain size according to the E19 ASTM scales using the Jeffers method. The diffusion stage is modeled on the basis of the approximation of the particle deformation model in the contact zones at the pressing stage using the Frenkel formula. Linear shrinkage is modeled based on direct measurement of sample sizes before and after sintering. The developed model has a certain versatility when applied to simulate the interaction of particles of metal powders under the conditions of the formation of porous briquettes, especially if the shape of the particles is close to round or spongy. The obtained result will make it possible to more accurately evaluate such a factor as the adhesion between the particles of the pressing and predict the tensile strength of the material. Additionally, due to the mathematical characterization of the peculiarities of the formation of corpuscular porosity under the conditions of sintering in a vacuum, we can design materials with differentiated porosity, as well as lay the foundations for powder 3D printing of such materials, by assembling grain by grain, or layer by layer with the adjustment of the force of particle compression one into the other.

Research Progress of Titanium Sponge Production: A Review

Titanium has excellent all-round performance, but the high cost of its production limits its widespread use. Currently, the Kroll process used to commercially produce titanium sponge is inefficient, energy-intensive, and highly polluting to the environment. Over the past few decades, many new processes have been developed to replace the Kroll process in order to reduce the cost of producing titanium and make it a common metal with as many applications as iron. These new processes can be divided into two categories: thermal reduction and electrolysis. Based on their classification, this paper reviews the current development status of various processes and analyzes the advantages and disadvantages of each process. Finally, the development direction and challenges of titanium production process are put forward.

Purification of titanium sponge produced by lithiothermic reduction of titanium tetrachloride: Effect of leaching conditions

The CSIR-Ti process employs lithiothermic reduction of titanium tetrachloride feedstock to produce titanium sponge. The product is therefore contaminated by a range of lithium and chloride species. In this study we examine the effects of particle size, temperature, and HCl concentration as input leaching variables on the removal of chlorides from the crude titanium sponge. A review of the aqueous chloride chemistry of Li and Ti provided initial conditions for leaching of impurity species from the sponge. Experimental results confirm that the effectiveness of leaching and removal of dissolved impurities from the sponge are dependent on leaching kinetics, which are influenced by temperature, particle size, and morphology. Of the variables tested, reaction temperature had the strongest influence on the oxygen content of the leached product. The HCl lixiviant concentration had a negligible effect under the conditions tested. Leaching of crude titanium sponge (-10 mm size fraction after crushing) at 14°C in either 1 M or 0.032 M HCl yielded a titanium sponge product that met the ASTM standard specification for commercially pure Grade 1 titanium, i.e., oxygen content < 0.18 mass% and chloride content < 0.15 mass%.