Papers by Keyword: Titanium

Abstract: There is a growing demand in the dental implant sector which aims to recreate the exact function and appearance of natural teeth, including strength, textures, and seamless blending with nearby teeth. Therefore, choosing the best crown material is a vital and challenging decision. To address this challenge, current study employs a comprehensive approach using Finite Element Analysis (FEA) on a 3-D CAD model. The stress analysis was carried out on three different crown materials - commercially pure Titanium (cp Ti), Zirconia (ZR), and Lithium Disilicate (LD) and compared their performance with that of human tooth material. The computational analysis results reveal that the pure Titanium (cp Ti) crown has shown the least deformation while the LD crown has showed the highest deformation under same loading conditions. When maximum stress is compared, Titanium showed the highest value, followed by Zirconia, whereas Lithium Disilicate (LD) demonstrated stress and deformation levels comparable to those of natural teeth.

Abstract: The effects of heat treatment in different ambient pressures or oxygen concentration on the wettability of the titanium (Ti) surface were examined. Polished titanium plates were heat-treated at various temperatures and periods in the pressure-controlled or oxygen concentration-controlled atmospheres. The wettability was evaluated by water contact angle measurement. The X-ray photoelectron spectroscopy was performed on the heat-treated and stored Ti surface to analyze adsorbates and surface products. The heat-treated Ti in the atmospheric air became hydrophilic due to the desorption of hydrocarbons on the surface. Then, the adsorption of hydrocarbons during storage in the atmospheric air returned its wettability to that before heating. On the other hand, the heat-treated Ti in a vacuum (low ambient pressures) or low oxygen concentration became hydrophobic due to an increase in the CH/OH (hydrocarbon/hydroxyl group) ratio on the surface. The wettability of hydrophobized Ti retained its wettability during storage in the atmospheric air.

Abstract: This presentation provides an overview of the recent collaboration between CSIRO and The Boeing Company focused on developing preforms of high-temperature titanium alloys. This collaboration devised a new method for manufacturing preforms, shaped intermediates and mill products directly from titanium powder. These preforms can then undergo thermomechanical processing to produce parts requiring minimal surface finishing with the desired microstructure and mechanical properties.

Abstract: Due to its low density, high strength to weight ratio, and been unreactive to the human body, titanium is commonly used in human bone implants. Titanium in bone implants can be used in its porous form because the porosity reduces the elastic modulus of the implant, near to that of human cortical or trabecular bone, which prevents the effects of stress-shielding. To date, majority of the published studies using the space holder (SH) method to produce porous titanium, utilized-45 μm titanium hydride dehydride (Ti-HDH) powder, or similar titanium powder. However, there is limited research conducted on the use of coarse titanium powder particles, such as-150 μm Ti-HDH powder to produce porous titanium. Fine Ti-HDH powders are known to have higher oxygen content than coarse Ti-HDH powders, thus the specimens produced from fine powders are harder, require higher compaction pressures and are expected to have lower impact resistance. The following study thus investigated the use of-150 μm Ti-HDH powder to produce porous titanium specimens, by the SH method. The porous specimens of 45 mm diameter were produced by uniaxially compacting mixtures of sodium chloride (NaCl) powder and Ti-HDH powder at 500 MPa. The NaCl powder utilized was hand sieved to a range of-500 μm. The specimens were sintered at 1150 for 4 hours in a high-vacuum tube furnace. Three porosity levels were investigated i.e. 40%, 50% and 60%. The sintered compacts were assessed for density, porosity and elastic moduli. It was found that the sintered porosity of the specimens ranged from 42.7-59.1%, and the sintered density ranged from 1.84-2.58 g/cm³. The elastic moduli of the specimens were found to reduce as the porosity increased, and ranged from 0.59-1.3 GPa, which is similar to the elastic moduli of human trabecular bone. The use of-150 μm Ti-HDH powder is thus potentially a lower cost alternative, than the use of-45 μm Ti-HDH powder, to produce porous titanium for human bone implants.

Abstract: For the processing of metal powders by Metal Injection Moulding (MIM) or indirect methods of Additive Manufacturing (AM), such as material extrusion (MEX-AM) polymers of different kinds are employed. Usually, the task of these polymers is to enable the shaping of a certain geometry and to maintain this shape down to the first cohesive effects of sintering. Nowadays, for the production of metal parts one goal is to get rid of the polymer as complete as possible. Another possibility is to use the polymer or at least part of it, mainly the carbon, for the metallurgical process of forming the final part in sintering as a process of heat treatment. Titanium is a metal, which is reacting with carbon easily. The question in focus here is how to utilise the carbon or some of it in the powder metallurgical processing of titanium. For first steps into this question, we selected two different powders, CPTi and TiH₂, and mixed them with two different polymers, polypropylene PP and low-density polyethylene LDPE. As a compatibilizer stearic acid SA was used. The polymers were selected because they are normally used as backbone in binder systems, and show a significantly different thermal degradation behaviour. Thus, the amount and type of carbon during thermal degradation could be expected to be different. The study comprises the preparation of polymer-powder blendings with up to 80 vol.% powder to resemble the conditions after solvent debinding; the shaping in discs, and TG-DTA experiments in air and in Ar to find out the temperature of backbone removal (Tr). Isothermal experiments are also done to know about the polymer removal with time. The different interaction of the polymers with the titanium powders is investigated, with a special attention to the interaction of hydride decomposition and polymer degradation. Keywords: Metal Injection Moulding; indirect Additive Manufacturing; titanium and titanium alloys; powder-polymer interaction

Abstract: Additive Manufacturing technologies revolutionize the production of 3D components by selectively depositing material layers, facilitating intricate geometries and cavities with minimal material waste. Among these techniques, Plasma Metal Deposition (PMD) stands out as a powder-based method offering promising applications, particularly in the aerospace sector.In this study, five specimens manufactured via PMD have been investigated, employing a base material of Grade 2 titanium and a welding material comprising a powder blend of grade 1 titanium and 30% B₄C particles. The incorporation of boron carbide aims to further augment the already commendable properties of titanium, catering to the stringent requirements of the aerospace industry.Attention is directed towards key manufacturing parameters such as the transferred arc and torch travel speed, while maintaining fixed parameters including pilot arc, current, and torch-substrate height. The primary objective of this research is to comprehensively explore the PMD technique, scrutinizing potential thermodynamic reactions during the welding process between titanium and boron carbide. Concurrently, thorough characterization of the specimens will be conducted to elucidate their properties.This project seeks to optimize the PMD manufacturing process and enhance the performance characteristics of the produced parts, thereby addressing critical needs in the aerospace sector. By unravelling the intricacies of thermodynamic interactions and material properties, we aim to pave the way for advancements in additive manufacturing methodologies and the production of high-performance titanium components for aerospace applications

Abstract: In the aerospace industry, titanium and its alloys have garnered significant attention for their low density, rendering them highly desirable materials. Nonetheless, their wear resistance has posed challenges, prompting extensive research into titanium-based composite materials. This study investigates the tribological performance of various titanium-based metal specimens reinforced with distinct ceramic and intermetallic materials. Specifically, specimens were fabricated to include a 20% volume fraction of pre-alloyed TiAl intermetallics, renowned for their reduced density, while others incorporated 30% boron carbide (B₄C). All specimens were meticulously prepared using Inductive Hot Pressing under optimized conditions. The primary objective is to discern the most effective option in terms of wear resistance. Comprehensive analyses, encompassing mass loss measurements, track width evaluations, wear assessments, and friction coefficient analyses, were conducted to achieve this goal.

Abstract: This study delves into the nuanced challenges of additive manufacturing, specifically focusing on the application of sinter-based processes for reactive materials, with Titanium as the focal point. The thermal debinding and sintering processes, crucial steps in shaping, are analyzed with an emphasis on the intricate control required for the removal of polymeric binders, especially concerning the reactivity of metals during these processes. Historically, the emphasis has been on materials like 316L and 17-4-PH due to their straightforward thermal debinding and sintering processes. However, the shift to Titanium and its alloys introduces complexities, requiring special debinding and meticulous control of interstitial elements such as C and O to adhere to stringent material standards such as ASTM F2885-17. This research examines the various stages of shaping progressions, addressing specific requirements like green part strength, flexibility (filaments), flowability (Metal Injection Molding), and crosslinking (Stereolithography). The focus lies on achieving thermal removal with minimal residuals and reactivity, particularly in the context of reactive metals. Lithography-Based Metal Manufacturing (LMM) and Cold Metal Fusion (CMF) emerge as significant additive manufacturing processes for small to medium-sized batches of titanium parts, utilizing sinter-based production setups. Both processes not only serve as alternatives to Metal Injection Molding but also contribute to cost-effectiveness and sustainability through the efficient reuse of unused feedstock. The selection of the optimal shaping technology for individual parts becomes critical, considering mechanical properties, final density, acceptance of interstitials, complexity, wall thickness, overhangs, and internal structures. This presentation provides a detailed analysis of Lithography-Based Metal Manufacturing, comparing it with the Cold Metal Fusion process. Key considerations include mechanical properties, surface finishes, and cost, shedding light on the technical intricacies and trade-offs inherent in each technology.

Abstract: This study focuses on developing a composite material using graphene oxide (GO) as a dielectric film. First, GO was mixed with DI water and dried to form a film. Then, a titanium (Ti) film was deposited on the film surface through electron beam evaporation. The composite comprising graphene oxide with the Ti metal film was then dispersed in water, to which cellulose nanofiber (CNF)—noted for its high mechanical strength, stability, and lightweight attributes—was added. The mixture was then re-layered with cellulose nanofibers by agitating it in water, and subsequently dried to form a composite film. The electrical properties of the material were studied using an LCR meter. The results show that pure GO has a dielectric constant of about 1600 at 1 kHz and a dielectric loss of about 25. After adding Ti, the Ti composite film maintained a dielectric constant above 1000 at 1 kHz while significantly reducing the dielectric loss to 1.5. Additionally, the resistivity of pure GO at 1 kHz is approximately 1200 Ω·m, whereas the Ti composite film with Ti and cellulose nanofibers shows a resistivity as high as 50 k Ω·m at 1 kHz. The relationship between dielectric strength and resistivity indicates that the Ti composite film can withstand higher voltages compared to pure GO, demonstrating a significant increase in dielectric strength. Compared to graphene oxide, the Ti composite film combines high dielectric constant, low dielectric loss, and increased dielectric strength.

Abstract: In this study, carbonate apatite [Ca_10-x(PO₄)_6-y(CO₃)_z(OH)_2-x-y-z, CHAp], a bone substitute material, was coated on roughened titanium through a sol-gel hydrothermal method. The sol-gel process was used to prepare calcium tartaric complexes, which were then subsequently hydrothermally treated on titanium in the presence of sodium hydroxide, and sodium hydrogen phosphate. The results showed that carbonate apatite, composed of nanosized fibers, was evenly deposited across the titanium surface. This coating resulted in a lower surface roughness (Ra) value of 1.31 μm compared to 3.98 μm for uncoated titanium. Additionally, the carbonate apatite coating decreased the contact angles of the titanium surface, thereby significantly enhancing cell attachment and migration compared to the uncoated surface. These results could be valuable for further evaluation of this coating in biomedical applications.