Titanium Particle Size Research Articles

Production of porous titanium structures by combining hot isostatic pressing and solid-state foaming

The Hot Isostatic Pressing (HIP) process is based on the combined action of high levels of pressure and temperature. In general, such a process is used for reducing or eliminating microporosities in the component, especially when it is produced by additive manufacturing (AM) or casting. In the present work HIP is used for compacting TI6Al4V-ELI powders by means of a pressurized Argon gas acting at high temperature on a sealed can under vacuum in which Argon is previously inflated; thus, a subsequent Solid-State Foaming (SSF) heat treatment allows to produce a Titanium foam without any melting by exploiting gas entrapment. Samples extracted from billets produced setting different HIP parameters (size of Titanium particles and pressures) have been investigated in this work by means of heat treatments in furnace for the SSF: the temperature was kept constant (1020 °C), but the duration was varied in the range 1 - 6 h; the samples were finally analysed by Light Microscopy. Finally, the Response Surface Method (RSM) was used to determine the conditions able to increase both the size and the percentage area of the pores in order to fully control both the involved processes (HIP and SSF). Experimental results revealed that the porosity determined by the SSF is strongly affected by HIP parameters and by the SSF duration: the highest dimension of Ti particles and the highest level of Argon pressure determined the largest values of porosity, in terms of both percentage and pore dimension. The investigated process for producing porous titanium structures can be properly and efficiently combined with manufacturing processes able to create highly customised parts, not only in terms of geometry but also in terms of porosity.

Effect of powder and process parameters on in-situ alloying of nitinol during laser powder bed fusion

Powder characteristics such as flow energy, bulk density, compressibility, morphology, particle size distribution (PSD) and laser energy absorbtivity have a significant impact on the Laser Bed Powder Fusion (L-PBF) process. The impact of powder characteristics on in-situ nickel-titanium alloy formation within the L-PBF process is not well understood. In this work, the characteristics of nickel, titanium and two elemental blends of nickel-titanium powder were compared with those of a pre-alloyed nitinol powder. L-PBF solidification tracks were generated using selected powders and characterised for resulting track dimensions and chemical homogeneity. This study demonstrates that the melt homogenisation time and the size of titanium particles relative to nickel particles are critical factors for successful in-situ alloying of nitinol within the L-PBF process. The variation in elemental composition within solidification track cross sections, as measured by EDX point spectra, was found to increase significantly for laser scanning speeds of 400 mm/s and above. Furthermore, the elemental composition inhomogeneity with increasing laser scan speed was found to be significantly more pronounced for a nickel-titanium powder blend of spherical particles with average titanium particle size of 48 μm compared to an otherwise similar blend with an average titanium particle size of 32 μm. There was no significant difference recorded between solidification track widths of in-situ alloyed blends compared to pre-alloyed blends, indicating that optimal hatch spacing for in-situ alloying is likely to be similar to that required for pre-alloyed powders.

Quantity and Size of Titanium Particles Released from Different Mechanical Decontamination Procedures on Titanium Discs: An In Vitro Study.

Complications such as peri-implantitis could ultimately affect the survival of a dental implant. The prevention and treatment of peri-implant diseases require managing bacterial biofilm and controlling environmental risks, including the presence of pro-inflammatory titanium (Ti) particles in the peri-implant niche. Objectives included the evaluation of the size and quantity of Ti particles released from moderately roughened Ti surfaces during common mechanical surface decontamination methods. One hundred and forty moderately roughened Ti discs were divided into seven groups (n = 20 per group); six groups received mechanical decontamination procedures (ultrasonic scaling (US) with a metal tip and poly-ether-ketone (PEEK) under low and medium power settings, air-polishing with erythritol powder, and Ti brush), and the control group underwent air-water spray using a dental triplex. The rinsing solution was collected for Ti mass analysis using inductively coupled plasma mass spectrometry (ICPMS), as well as for Ti particle size and count analysis under scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). US metal tip instrumentation generated 34.00 ± 12.54 μg and 34.44 ± 6.08 μg of Ti under low and medium power settings, respectively. This amount of Ti generation was significantly higher than other instrumentation methods. The mean Ti particle size of the US groups ranged from 0.89 ± 0.27 μm to 1.25 ± 0.24 μm. No statistically significant difference was found in the particle size among US groups and Ti brush group (1.05 ± 0.11 μm), except for US with the PEEK tip, where a significantly smaller mean particle diameter was found at the low power setting (0.89 ± 0.27 μm). Mechanical instrumentation can produce Ti particulates and modify the implant surfaces. US using a metal tip generated the highest amount of Ti with smaller Ti size particles compared to all other commonly used mechanical surface instrumentations. The EDS analysis confirmed Ti in PEEK US tips. It can be suggested that deterioration from the PEEK US tip and Ti brush, as observed under SEM, is an additional source of Ti release during Ti surface decontamination.

Исследование расстеклования аморфных наночастиц титана в вакууме и в алюминиевой оболочке: молекулярно-динамическое моделирование

The process of the devitrification of titanium nanoparticles in a vacuum and in an aluminum shell was studied at heating rate of 5∙1011 K/s by the molecular dynamics method. Additional consideration of the influence of the aluminum shell is related to the solution of the issue of reducing the temperature of the initiation of the high-temperature synthesis reaction in the Ti-Al system in mixtures subjected to preliminary mechanical activation. It is shown that the change in the devitrification temperature compared to a bulk sample is inversely proportional to the particle diameter: as the particle size decreases and, accordingly, the proportion of atoms near the interface increases, the devitrification temperature increases. The presence of an aluminum shell leads to a significant increase in the devitrification temperature of titanium nanoparticles - for the considered sizes of nanoparticles (diameter from 1.75 to 11 nm) the difference was about 200 K. Thus, a decrease in the size of titanium particles and the presence of an aluminum shell increase the temperature range for the existence of the amorphous phase of titanium. The mechanisms of the nucleation of the crystalline phase in particles in a vacuum and in an aluminum shell are significantly different: in the first case, crystal nuclei are formed near the surface; in the second, on the contrary, in the bulk of the particle.

Correlation between the size of released titanium particles and changes in the surface of dental implants during insertion into bone blocks: an in vitro study.

This study investigated the size and amount of titanium particles immediately released following dental implant insertion into bovine bone blocks and aimed to correlate them with the surface roughness of the implants. Twelve bone blocks were prepared from bovine mandibles. Six tapered (group A) and 6 cylindrical (group B) dental implants were inserted into the bone blocks under water irrigation, following the standard drilling protocol. After insertion, the implants were immediately removed from the bone. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy were performed to investigate the released titanium particles and implant surface roughness, respectively. The amount of titanium ions in the irrigation water was measured using inductively coupled plasma mass spectrometry. Dynamic light scattering (DLS) was used to determine the size range of the released titanium particles. The percentages of titanium content on the surface of implants decreased in both groups after implantation into bone blocks. SEM-EDX analysis confirmed the presence of titanium particles embedded in the implanted bone bed. Group B implants showed significantly higher concentrations of titanium ions in the collected water than group A implants (0.868 and 0.565 µg/L, respectively). Group A implants demonstrated high pre-implantation surface roughness, which led to a much greater decrease in post-implantation surface roughness than was observed for group B implants. DLS analysis showed that the titanium particles released from group A implants were within the nano-size range, whereas those released from group B implants were within the micro-size range. Dental implant placement leads to a decrease in implant surface roughness and the immediate release of titanium particles into the peri-implant bone. Variations in the size range and amount of released particles were correlated with implant surface roughness. This finding has clinical implications and warrants additional in vivo studies.

Investigating the influence of titanium particle size and concentration on osteogenic response of human osteoblasts - in vitro study.

The purpose of this study was to investigate the correlation between the size and concentration of titanium particles and the osteogenic response of human osteoblasts (HOB). Different concentrations of titanium dioxide nano- and micro-particles were prepared and their biocompatibility on HOBs was analyzed using XTT assay. The changes in the actin cytoskeletal organization were studied by confocal laser scanning microscopy. The generation of intracellular reactive oxygen species (ROS) by HOBs after exposure to titanium dioxide particles was analyzed using ROS assay. Besides, the osteogenic potential represented by alkaline phosphatase activity, osteoprotegerin, macrophage colony stimulating factor levels, and biomineralization were analyzed. Short-term interaction of titanium dioxide nano- and micro-particles did not induce toxicity to HOBs. However, cells treated with 100 μg/mL titanium dioxide nano- and micro-particles demonstrated higher ROS generation compared to control. Besides, cells treated with 100 μg/mL titanium dioxide nanoparticles showed higher alkaline phosphatase activity, osteoprotegerin, macrophage colony stimulating factor levels and biomineralization compared to titanium dioxide microparticles. Collectively, the study found titanium dioxide nanoparticles to be more biocompatible than microparticles providing an insight into the capability of nanostructures in supporting osteoblast differentiation and its plausibility in biomedical applications.

SYNTHESIS OF TITANIUM (IV) OXIDE AND PROSPECTS OF ITS APPLICATION IN ADSORPTION AND PHOTOCATALYTIC WATER TREATMENT PROCESSES

Pure titanium oxide (TiO2(ng)) and modified with potassium fluoride with different percentage of dopant: 2, 7, 15% (TiO2(2F), TiO2(7F), TiO2(15F), respectively) samples were synthesized by low-temperature sol-gel method. The morphology and particle size of pure titanium(IV) oxide (TiO2(ng)) and titanium(IV) oxide doped with potassium fluoride (TiO2(2F)) were investigated by scanning electron microscopy method. It was found that the doping with potassium fluoride does not have a significant effect on the shape of the particles, but allows to narrow the particle size distribution. X-ray phase and X-ray structural analyzes of the obtained TiO2 samples showed that the predominant phases of pure TiO2 were rutile and brookite, and only anatase contained in TiO2 doped with KF. The porous structure of the synthesized TiO2 samples was studied by the method of low-temperature nitrogen adsorption-desorption. It was found that the all obtained TiO2 samples belonged to porous adsorbents, the adsorption of which carried out monolayer. The adsorption properties of the obtained TiO2 samples were investigated using a model pollutant, phenol. It was found that the best adsorption properties showed TiO2(2F) sample at all three concentrations of pollutant. The maximum adsorption degree of phenol with an initial concentration of 3.125 mg/dm3 (18%) was achieved by TiO2(2F) sample; with an initial phenol concentration of 6.25 mg/dm3 was 21.5%, and at an initial phenol concentration of 12.5 mg/dm3 it was 42%. The highest photocatatical activity was shown by the sample of low-doped fluorine TiO2, in the presence of which phenol was decomposed by 68%.

Effect of the Size of Titanium Particles Released from Dental Implants on Immunological Response.

The techniques used in oral implantology to remove bacterial biofilm from the surface of implants by machining the titanium surface (implantoplasty) or by placing rough dental implants through friction with the cortical bone generate a large release of particles. In this work, we performed a simulation of particle generation following clinical protocols. The particles were characterized for commercially pure titanium with particle sizes of 5, 10, 15, and 30 μm. The aim was to determine the effect of particle size and chemical composition of the implant on the immune response. For this purpose, their morphology and possible contamination were characterized by scanning electron microscopy and X-ray microanalysis. In addition, the granulometry, specific surface area, release of metal ions into the medium, and studies of cytocompatibility, gene expression, and cytokine release linked to the inflammatory process were studied. The release of ions for titanium particles showed levels below 800 ppb for all sizes. Smaller particle sizes showed less cytotoxicity, although particles of 15 μm presented higher levels of cytocompatibility. In addition, inflammatory markers (TNFα and Il-1β) were higher compared to larger titanium. Specifically, particles of 15 μm presented a lower proinflammatory and higher anti-inflammatory response as characterized by gene expression and cytokine release, compared to control or smaller particles. Therefore, in general, there is a greater tendency for smaller particles to produce greater toxicity and a greater proinflammatory response.

Macrokinetic Mechanism of the Combustion of 5Ti + 3Si Powder and Granular Mixtures: Effects of the Release of Impurity Gas and the Size of Titanium Particles

Macrokinetic Mechanism of the Combustion of 5Ti + 3Si Powder and Granular Mixtures: Effects of the Release of Impurity Gas and the Size of Titanium Particles

Study of the influence of titanium and niobium particle size on the Ti35Nb alloy production with controlled porosity

The present work is a continuation of the research carried out in a previous work, with the aim of improving the production of Ti35Nb alloy by reducing the particle size of Ti (from 50–149 Μm to < 53 Μm) and Nb (from 31–500 Μm to < 62 Μm) powders. Micro (MI) and Macroporous (MA) Ti35Nb alloy samples were processed by powder metallurgy. Ammonium bicarbonate (AB) was utilized as pore former additive for processing MA samples. The powders were mixed, uniaxially pressed and then sintered at 1300 ºC for 2 hours under argon atmosphere. The samples were characterized by SEM/EDS, XRD, profilometry, and Vickers hardness test. The porosity levels were determined by geometric method, Archimedes’ principle and quantitative metallographic analysis. The results showed that the processing parameters used in this work successfully produced porous Ti35Nb alloys with completely stabilized β-Ti phase, indicating an enhancement in the methodology when compared with those reported in previous work. Smaller particle sizes influenced positively on the chemical-physical properties of MI and MA samples, since they demonstrated an improvement in the their characteristics, such as: more homogeneous microstructure; better particle consolidation; homogeneous elemental distribution with no relevant chemical contamination; porosity values in accordance with literature; presence of low amounts of titanium oxides on the surfaces which can improve the biocompatibility features; suitable surface roughness parameters for bone implant applications and favouring adhesion of bioceramic coatings; more uniform microhardness values for both samples which make the material with a further predictable mechanical behavior.

Features of titanium and aluminum particles combustion

The results of the study of metal particles combustion process in free fall in air are presented. Titanium particles with a size of 120-540 microns and particles-aluminum agglomerates with a size of 540-660 microns were used. The characteristic times of the beginning and the end of fragmentation, the end of combustion were found with help of video filming. The laws of particles motion, in particular, their velocity and coordinate at the moment of the beginning of fragmentation, were determined. The size of titanium particles at which the fragmentation mode changes (“star” and “spruce branch”) were estimated. Condensed combustion products of particles were selected and investigated.

Influence of Granulation and Ni-Containing Binder Composition on the Self-Propagating High-Temperature Synthesis of Carbides in the Ti–Cr–C System

We have studied the combustion process and the phase composition of its products using granulated 70 wt % (Ti + C) + 30 wt % (3Cr + 2C) and 80 wt % (Ti + C) + 20 wt % (3Cr + 2C) mixtures with nickel-containing binders. The results demonstrate that the addition of a nickel binder reduces the chromium content of the (Ti,Cr)C double carbide, because nickel reacts with chromium to form Nichrome. In the case of combustion of the granulated 80 wt % (Ti + C) + 20 wt % (3Cr + 2C) mixture with the addition of Kh20N80 Nichrome, a Nichrome-binder-containing (Ti,Cr)C double carbide essentially free of impurity phases according to X-ray diffraction data has been prepared in a single step. A two-step mechanism of final product formation has been proposed. According to scanning electron microscopy data, the grain size of the combustion products is 2–5 μm, which is an order of magnitude smaller than the initial titanium and chromium particle size. In contrast to powder mixture combustion products, which are difficult to disintegrate, the agglomerate obtained via the combustion of a granulated mixture broke into separate granules, which could be ground to a desired particle size under laboratory conditions.

Balancing Reactant Transport and PTL-CL Contact in PEM Electrolyzers by Optimizing PTL Design Parameters via Stochastic Pore Network Modeling

Optimizing the porous transport layer (PTL) structure is crucial for high current density operation of polymer electrolyte membrane (PEM) electrolyzers. Previous studies from the literature demonstrated that PTL structures, mainly porosity and titanium powder diameter, can be strategically chosen to improve the performance (1-3). However, transport mechanisms in the PTL can be further explained from the perspective of mass transport. In this work, we employed modelling approaches to investigate the effect of porosity and titanium particle size of the sintered titanium powder based PTL on mass transport. PTLs were numerically generated using a stochastic model (Figure 1) with three titanium powder diameters, 25 µm, 50 µm, and 75 µm, and three porosities, 26.5%, 40.5%, and 63.5%. Pore network modelling was used to calculate the gas saturation and the permeability of liquid water in the presence of oxygen gas. We observed that all simulated PTLs exhibited similar gas saturation profiles and relative permeabilities, yet the PTLs with higher porosities had significantly higher liquid water permeabilities. For a constant powder diameter of 25 μm, increasing the porosity from 26.5% to 63.5% led to an increase in the average surface roughness from 8.9 μm to 38.6 μm. For a constant porosity of 26.5%, increasing the powder size from 25 μm to 75 μm resulted in an increase in the average surface roughness from 8.9 μm to 18.3 μm. Larger open pore spaces were acquired for PTLs with higher surface roughness, resulting in higher liquid water permeabilities (two-phase permeability). Therefore, PTLs with higher porosities and larger particle sizes provide superior liquid water permeation and gas removal. Figure 1. The 3D reconstruction of the PTL generated with titanium powder diameter of (a) 25 µm, (b) 50 µm, and (c) 75 µm at overall porosity of 40.5%. References S. A. Grigoriev, P. Millet, S. A. Volobuev and V. N. Fateev, Int J Hydrogen Energy, 34, 11, p. 4968-4973 (2009). J. O. Majasan, F. Iacoviello, P. R. Shearing and D. J. Brett, Energy Procedia, 151 (2018). L. Zielke, A. Fallisch, N. Paust, R. Zengerle and S. Thiele, Royal Society of Chemistry Advances, 4, p. 58888-58894 (2014). Figure 1

Preparation of TiAl Alloy Powder by Reactive Synthesis in Molten KCl-LiCl Salt

TiAl alloy powders were simply and economically prepared by reactive synthesizing of elemental powders in molten salt, and the synthesis process and powder characteristics were investigated . The results showed that the reaction in the molten salt was completed when the temperature was heated to 750°C. A higher content of salt resulted in a decreased particle size and the optimum content of salt for synthesizing TiAl alloy powders was 83 wt.%. The particle size of the synthesized powders was decreased with reducing the titanium particle size, and kept unchanged with the variation of Al powder particle. The oxygen content of the prepared powders was affected by the raw powder particles and was decreased to a level of less than 0.20 wt.% after the de-oxygenation processing. The atomic diffusion rate for titanium and aluminum was accelerated in the molten salt and their reaction temperature was decreased .

Effect of Ti Particle Size on the Reaction Kinetics and Densification of TiAl Intermetallics

The present investigation deals with response of the particle size of titanium on the reactive sintering of Ti–Al intermetallics and subsequently on their reaction kinetics and densification behavior. Titanium powders of the initial average particle size of 44 μm were milled for various durations in a planetary ball mill to produce average particle sizes of 100, 28 and 7 μm. These titanium powders of various particle sizes, i.e. 100, 28, and 7 μm were mixed with titanium powder of average particle size range of 40–44 μm in the ratio of 1:1 corresponding to the Ti–Al intermetallic composition. The reactive sintering temperatures of the mixtures were determined by DTA and the effect of change in Al particle size was determined for the activation energy of the self propagating reaction. The mixtures of Ti and Al blends of various Ti particle size were compacted and subsequently sintered at reaction sintering temperatures for 1 h in argon atmosphere. The porosity levels as well as the microstructure studies were carried out to determine the influence of the particle size of aluminium on the reactive sintering of Ti–Al. The compacts were further characterized by X-ray diffraction to determine the extent of phase formation.

Microstructure and Interconnections Characteristics of Titanium Foam

Titanium foams are widely used as biomaterials and potentially as a twin skinned, sandwich, structures for aerospace structures, filter or a catalyst or catalysts carrier for chemical reactions. The porosity is particularly important for tissues ingrowth and vascularity. Open porosity is essential in the case of flow-on machines. The distribution and size of pores is significant to achieve a uniform material effort and ensure to receive an appropriate hydraulic properties.The aim of this study was to determine the effect of titanium particle size and the amount of porogen on the microstructure and the size of pore interconnections in titanium foams made using saccharose as the space holder material.The paper characterizes titanium foam, made from the Grade 1 Ti powders (Alfa Aesar) with a particle sizes of 0.150 mm and 0.044 mm (separately) and spherical particles of saccharose (Pfeifer &amp; Langen) having an average size of 0.7 ÷ 0.9 mm, as a porogen. There was prepared a mixture of powders of the proposed porosity of 50, 60 and 70%. Summarizing 6 mixtures were prepared. After sintering there were received specimens having a diameter of 8 mm and a height of 5 mm. Microstructure analysis was performed using the microtomography Skyscan 1172 (Bruker microCT) and the CTAn software (Bruker microCT).The results indicate the uniform pore distribution and size of the interconnections allowing high permeability.

Effect of Particle Size of Titanium and Nickel on the Synthesis of NiTi by TE-SHS

In this work, the influence of the particle size of nickel and titanium on the synthesis of NiTi shape memory alloy by self-propagating high-temperature synthesis (SHS) was investigated. It was found that coarse titanium and nickel powders undergo only a limited SHS reaction. On the other hand, too fine powders support the low-temperature diffusional formation of NiTi intermetallics at 773 K to 1073 K (500 °C to 800 °C) which could then suppress the SHS reaction. The optimum powder fraction of both nickel and titanium to achieve the most intensive SHS reaction is 25 to 45 µm. The influence of the particle size of both nickel and titanium on the reaction mechanism is discussed in terms of the microstructure evolution, phase, and chemical composition changes and thermal effects determined by differential thermal analysis.

Effect of Particle Size and Titanium Content on the Fracture Toughness of Particle-Ceramic Composites

Through an intense powder mixing produced in a planetary mill, they were manufactured Al2O3-ceramics strengthened with different amounts of Ti nano-particles. After milling, powders SEM observations show good dispersion of titanium in the mixture. From these observations it was estimated that the size of titanium particles is around 100nm, whereas, Al2O3 presents 1-2μm sizes. Then compacts made with mixed powder were pressureless at 1500°C during 2h. Resulting microstructures, show dense composites formed by an Al2O3-ceramic matrix with homogeneous immerse distribution of Ti nano-particles. Fracture toughness of the composites is directly dependent with the titanium content in the ceramic-matrix.

Effect of particle size on the formation of Ti2AlC using combustion synthesis

This paper provides an insight into the effect of particle size of elemental metal powders and carbon source on the formation mechanism of Ti2AlC MAX-phase ceramic produced by self-propagating high-temperature synthesis (SHS). The effect of titanium, aluminium and carbon particle size on the 2Ti+Al+C→Ti2AlC reaction, the phase evolution of the final product and the porosity in both the green body and product has been examined. The effect of the carbon source in the form of graphite, carbon black and short carbon fibres on the reaction mechanism is explained. It is found that the particle size of the titanium and aluminium reactants had little effect on the phases formed but affected the green density of the reactants and the porosity in the final product. The carbon source used in the combustion reaction had an influence on the phases formed by the SHS reaction and was influenced by the dispersion of carbon particles and the titanium–aluminium particle contact.

The Size and Shape Analysis of Titanium Particles in Composites from ZrO&lt;sub&gt;2&lt;/sub&gt; – Ti System

The morphology ZrO2-Ti composites depends on used powders substrates, methods of forming and sintering conditions. In this study a composite from the nanosize ZrO2 powder stabilized by 3 mol% Y2O3 and 3 vol. % Ti powder with particle size about 15 μm was prepared. A composite material was formed by uniaxial pressing. Sintering process was conducted in an argon atmosphere at 1300°C with retention time 2h. The selected physical properties of the green body and sintered ZrO2-Ti composites were determined by Archimedes method. The microstructural characterization was carried out using the x-ray diffraction and the scanning electron microscope (SEM) with EDS analysis. Stereological analysis by using computer programs was supported. The SEM observation and EDS analysis of the cross-section of the samples confirmed that the Ti particles are distributed homogenously in analysed areas. The EDS analysis revealed partial solution of titanium in ZrO2 matrix. Moreover, the x-ray diffraction exposed the existence of tetragonal zirconium oxide and titanium or a new phase from Ti-Zr-O system. The stereological analysis showed similarity between the starting particles of Ti powder and particles of titanium in the composite matrix.