通过关键词查论文: Titanium


作者: Jyotsna Dutta Majumdar
摘要: Laser as a source of focused energy may be applied for the modification of microstructure and/or composition of the near surface region of a component. The technique may be applied for the development of a ceramic/intermetallics/interstitial compound dispersed metal matrix composite layer on the surface of metallic substrate by melting the substrate with a high power laser and simultaneous addition of alloy powders for the development of metal matrix composite layer by in-situ reactions. In the present contribution, development of metal-dispersed and intermetallic-dispersed matrix composite layer on the surface of metallic matrix has been discussed with a suitable example of its application.
作者: Mishel Weschler, Aurora Antoniac, Danut Cojocaru, Iulian Vasile Antoniac
摘要: The purpose of our study was to compare the mechanical properties of the different abutment under the static loading, aspect treated by many researchers [1-4], especially following the improvements given by the new proposed three-piece abutment, described below. We evaluated the effect of compression loading on the screw joint stability of the two-piece abutment and a new proposed three-piece abutment connected to an internal hexagon implant in vitro.The dental implant used was type AlphaBio SPI with an internal hexagon shape with following dimensions: length 13mm and diameter 3.75mm. The two types of abutment were used: the common type consisting of two piece straight titanium abutment and the second type consisting of three piece abutment (two titanium pieces and the third piece made of UHMWPE). For two-piece titanium implant/abutment systems with a screw-retained connection, the respective prefabricated straight abutments were tightened with a torque gauge using titanium abutment screws (type M-TLA) according to the manufacturer’s instructions. In the second case, the first titanium piece was a connector base between the implant and the UHMWPE abutment body which is assembled all together with the implant abutment fixation screw. The experimental systems were positioned in bovine cortical bone with a central hole (3.75 mm in diameter), and mechanical characteristics were evaluated using mechanical tensile tests. The mechanical tensile tests were carried out using INSTRON 3382 tensile test equipment. All tensile tests were performed at a constant strain rate of 1mm/min until a maximum elongation of 4mm. Stress-strain tensile curves were obtained for each experimental system.There were significant differences in the case of using the system with three piece abutment and we could conclude that this type of abutment assure a lower pressing on the entire system due to the shock absorbent properties of the piece made by UHMWPE.
作者: Ehsan Sharifi Sede, Shamsedin Mirdamadi, Hossein Arabi
摘要: This study sought to create a biocomposite of Magnesium and Titanium via a powder metallurgy technique. Powder metallurgy technique was used to produce three different volume percentages of Magnesium (30% , 35% , 40%). Titanium powder was mixed with Magnesium, then the samples were compressed by 1800 Bar using a cold, isostatic press process. The samples were then sintered to 850 for 100 min. At this temperature, the compressive yield strength was increased to 210 Mpa and significantly depended on the volume percent of Magnesium present, the core size and temperature of sintering. The bioactivity of the samples in a simulated body fluid (SBF) was also investigated. When the samples were immersed in the simulated body fluid for a 14 and 28 days, calcium and other elements were found to be deposited on the surface. Additionally, it was found that TiO2 has the ability to induce the formation of bone-like apatite in the SBF. In addition, the degradation product of Magnesium in a biological system caused a rise in the pH and environment for the deposition of calcium and other element on the surface were enhanced. Finally, the samples were analyzed using XRD, EDS, and optical and scanning electron microscopy (SEM).
作者: Takashi Hayami, Masanobu Kusunoki
摘要: In order to impart both osseointegration and osteoconduction characteristics onto extruded pure polyetheretherketone (PEEK) for use as an artificial bone material, the surface of the PEEK was sputter-coated with a thin bilayer-film consisting of a commercially pure titanium (Ti) layer with a thickness of 90 nm and a hydroxyapatite layer with a thickness of 200 nm derived from simulated body fluid (SBF-HA). A specimen of PEEK coated only with Ti was used in peeling tests to determine the adhesive strength of the interface between the two materials, which was found to be 2.55 ± 0.45 MPa. Tensile tests were also carried out, and it was found that no exfoliation of the Ti film occurred until an ultimate strain of 129% was reached. In a cell culture test using mouse osteoblast on the bilayer-coated PEEK, cell proliferation following 168 h of culturing was 1.3 times higher on the SBF-HA than on synthetic hydroxyapatite, and 2.4 times higher than that on the Ti-coated PEEK. In addition, the proliferation on the Ti-coated PEEK was 2.1 times higher than that on uncoated PEEK.
作者: Arne Biesiekierski, James Wang, Cui'e Wen
摘要: In the realm of bioimplantation, titanium-based Shape Memory Alloys (SMAs) exhibit phenomenal versatility, with successful application in diverse fields. One area of particular interest is that of orthopaedics, where the unique properties of SMAs offer a range of benefits. That said, existing alloys still have unresolved issues concerning biocompatibility and osseointegration. Primary concerns include carcinogenicity, allergenicity and a significant mismatch between the Young’s moduli of bone and osteoimplants; issues that could be addressed via a novel porous titanium alloy. With that in mind, this paper seeks to provide a review identifying promising candidates for new, perfectly biocompatible alloys for production via powder metallurgy. Furthermore, an attempt will also be made to summarise existing research into appropriate methods for the production of a porous Ti-based SMA implant.
作者: Mariny F.C. Coelho, Maria E.R. Cronemberger, Juliete N. Pereira, Sandra Nakamatsu, Sylma Carvalho Maestrelli, Eliana C. da S. Rigo, Neide A. Mariano
摘要: Titanium and stainless steel are examples of biomaterials widely used in dental and orthopedic implants owing to their properties of good corrosion resistance and excellent biocompatibility. This paper reports on a study of the biomimetic method applied to titanium (cp-Ti) and 316L stainless steel. The method consists in immersing the metal substrate in a synthetic solution of SBF (simulated body fluid) whose composition, pH and temperature resemble those of human blood plasma. The coating on the two metals was effective for obtaining hydroxyapatite, which was confirmed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR).
作者: Khalil Farhangdoost, S. Rahnama
摘要: A comparison between crack growth rate (da/dN) vs. effective stress intensity range factor (ΔKeff) curve behavior and microscopic and macroscopic fracture surface of commercial Ti-6Al-4V alloy are presented. Three different regimes are correlated with characteristics measured on the fracture surfaces. Three regions can be observed in which part I is rough and darker than others parts known as pre-transition, part II is smooth and light known as transition region and part III is a little darker than part II known as post-transition region. In the present investigation the correlation of fatigue crack growth rate for Ti-6Al-4V and microstructure of fracture surface has been presented.
作者: Qing Wei Jiang, Lin Xiao, Xiao Wu Li
摘要: The temperature-dependent deformation and damage behaviors of ultrafine-grained (UFG) Cu and Ti produced by equal channel angular pressing (ECAP) were investigated and compared. It was found that ECAPed materials with different crystalline structures, e.g. the present fcc Cu and hcp Ti, exhibited significantly distinctive high-temperature deformation and damage characteristics. As the testing temperature is below recrystallization, small- and large-scale cracks or voids formed along the shear bands (SBs) on the surface of UFG Cu, whereas only a few fine shear lines and some non-propagation voids appeared on the surface of UFG Ti. As the temperature is above recrystallization, some small cracks (or voids) formed along grain boundaries and slip deformation took place in many coarsened grains, while only extrusions and intrusions instead of obvious cracks or voids are observable for UFG Ti. The corresponding microstructual changes after compressive deformation, e.g. grain coarsening, were also examined and confirmed by TEM observations.
作者: Kyriakos I. Kourousis
摘要: Advanced light metals have recently attracted the interest of the aerospace and automotive industry. The need for accurate description of their cyclic inelastic response under various loading histories becomes increasingly important. Cyclic mean stress relaxation and ratcheting are two of the phenomena under investigation. A combined kinematic isotropic hardening model is implemented for the simulation of the behavior of Aluminum and Titanium alloys in uniaxial mean stress relaxation and ratcheting. The obtained results indicate that the model can perform well in these cases. This preliminary analysis provides useful insight for the evaluation of the models capabilities.
作者: Ying Ying Sun, Shu Dong Luo, Ya Feng Yang, J.F. Sun, Ma Qian
摘要: Powder metallurgy (PM) of titanium hydride (TiH2) has emerged as an attractive alternative to PM of Ti. Microwave (MW) heating has the potential to further facilitate the development of PM TiH2 as TiH2 is essentially a ceramic material. A detailed assessment has been made of the effectiveness of MW heating of Ti-xTiH2 (x =0-100) powder compacts through 30 experiments conducted under a variety of conditions. MW hybrid heating (i.e. when assisted with a SiC MW susceptor) proved to be reliable and consistent in heating Ti-xTiH2 powder compacts and the heating rate increased progressively with increasing TiH2 powder content, indicating that TiH2 powder is more responsive to MW heating than Ti metal powder. However, heating of TiH2 powder compacts by MW radiation without the assistance of a SiC MW susceptor proved to be inconsistent and unpredictable, where successful heating (heated to 1300°C in 20 min) was achieved but many failures also occurred. However, the use of SiC can cause contamination (Si and C). The challenges of heating of TiH2 powder by direct MW radiation were discussed.