Search results for "Titanium"
showing 10 items of 878 documents
Atomic layer deposition of LixTiyOz thin films
2013
Atomic layer deposition (ALD) was employed to deposit ternary films of LixTiyOz. The film growth at a deposition temperature of 225 °C was studied using both titanium tetra-isoropoxide (Ti(OiPr)4) and titanium tetrachloride (TiCl4) as titanium precursors. Lithium tert-butoxide (LiOtBu) was applied as the lithium source and water was used as the oxygen source for all metal precursors. The type of titanium precursor chosen strongly affected film growth: with TiCl4 the resulting LixTiyOz films were highly air-sensitive and the lithium concentration was low, whereas with Ti(OiPr)4 the films were relatively stable in air and with a lithium content which was easily controlled over a wide range. F…
Influence of titanium-substrate roughness on Ca–P–O thin films grown by atomic layer deposition
2013
Abstract Amorphous Ca–P–O films were deposited on titanium substrates using atomic layer deposition, while maintaining a uniform Ca/P pulsing ratio of 6/1 with varying number of atomic layer deposition cycles starting from 10 up to 208. Prior to film deposition the titanium substrates were mechanically abraded using SiC abrasive paper of 600, 1200, 2000 grit size and polished with 3 μm diamond paste to obtain surface roughness R rms values of 0.31 μm, 0.26 μm, 0.16 μm, and 0.10 μm, respectively. The composition and film thickness of as-deposited amorphous films were studied using Time-Of-Flight Elastic Recoil Detection Analysis. The results showed that uniform films could be deposited on ro…
Experimental and numerical study of a fibre/matrix interface of SiC/titanium composites
1998
Resume Certains phenomenes dissipatifs dans les composites a fibres longues sont encore assez mal compris et notamment celui de la decohesion entre la fibre et la matrice. Cette etude s'interesse donc a ce phenomene dans les composites a matrice metallique SiC/Titane. L'analyse du phenomene est menee parallelement de maniere experimentale et numerique aussi bien a l'echelle des constituants qu'a celle du materiau homogene equivalent. Cela conduit a pouvoir identifier un critere local de decohesion aidant lui-meme a la determination d'un critere global de decohesion.
Residual stress and material flow prediction in Friction Stir Welding of Gr2 Titanium T-joints
2022
Friction Stir Welding is nowadays an established technique successfully used by many industries. However, most of the research and, consequently, most of the applications regard aluminum alloys and butt joints. T-joints are of high interest for different industrial sectors as aeronautical, aerospace, naval and ground transportation, for which joint integrity and low residual stress are extremely important. In this study, an experimental and numerical approach is proposed with the aim to study the peculiarities of the residual stress distribution and material flow occurring in FSW of CP-Ti T-joints. Experiments were carried out to assess the feasibility of the process and to acquire the temp…
Heterogeneous Photocatalysis and Photoelectrocatalysis: From Unselective Abatement of Noxious Species to Selective Production of High-Value Chemicals
2015
Heterogeneous photocatalysis and photoelectrocatalysis have been considered as oxidation technologies to abate unselectively noxious species. This article focuses instead on the utilization of these methods for selective syntheses of organic molecules. Some promising reactions have been reported in the presence of various TiO2 samples and the important role played by the amorphous phase has been discussed. The low solubility of most of the organic compounds in water limits the utilization of photocatalysis. Dimethyl carbonate has been proposed as an alternative green organic solvent. The recovery of the products by coupling photocatalysis with pervaporation membrane technology seems to be a…
Chemical Engineering of Photoactivity in Heterometallic Titanium–Organic Frameworks by Metal Doping
2018
[EN] We report a new family of titanium-organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi-gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization. Compared to other methodologies based on the post-synthetic metallation of MOFs, our approach is well-fitted for controlling the positioning of dopants at an atomic level to gain more precise control over the band-gap and electronic properties of the porous solid. Changes in the band-gap are also rationa…
Effects of an Er : YAG laser and the Vector® ultrasonic system on the biocompatibility of titanium implants in cultures of human osteoblast-like cells
2003
Abstract: The aim of the present study was to investigate the effects of an Er : YAG laser (ERL) and the Vector® ultrasonic system (VS) on the biocompatibility of titanium implants in cultures of human osteoblast-like cells (SAOS-2). One hundred and sixty-eight titanium discs with four different surfaces (sand-blasted and acid-etched, titanium plasma-sprayed, machine-polished, and hydroxyapatite-coated) were used to evaluate cell attachment. The samples were equally and randomly assigned to the following groups: (1) an ERL at an energy level of 100 mJ/pulse and 10 Hz using a special application tip, (2) the VS using carbon fibre tips, or (3) untreated control (C). The discs were placed in c…
Effects of various hygiene procedures on the surface characteristics of titanium abutments.
1996
The use of cleaning instruments on titanium implants may cause undesired surface alterations. In a qualitative and quantitative assessment of these alterations, 5 titanium implant abutments were treated with a steel curet, a prototype pure titanium curet, an air abrasive polishing system, and an ultrasonic system. Custom-made polymer templates, used to secure the curet to a vertical guide bar and a spring scale to maintain a constant instrument pressure, guaranteed a standardized procedure and reproducible results. The ultrasonic and the air abrasive polishing method were also standardized. Evaluation by scanning electron microscopy (SEM) revealed surface alterations for all instruments and…
Effect of apical root-end filling materials on gingival fibroblasts
2003
AIM To determine the influence of root-end filling materials on specific cellular responses of gingival fibroblasts (GF). METHODOLOGY The reactions of cells in contact with mineral trioxide aggregate (MTA), amalgam and a chemically inert titanium alloy were determined based on the assessment of prostaglandin (PGE2) release with and without arachidonic acid stimulation, protein and lactate synthesis, and cell proliferation. Cells cultured without test materials served as controls (100%). RESULTS The fibroblasts showed a highly significant decrease in protein synthesis when in contact with amalgam (61.8 +/- 13.6%); MTA (91.2 +/- 5.9%) and titanium (92.4 +/- 4.7%) had little effect on this par…
Effect of the TiO2 nanoparticles on the selected physical properties of mineral trioxide aggregate
2017
Background Some of the efforts to improve the properties of Mineral Trioxide Aggregate (MTA) include incorporation of some nanoparticles such as Titanium dioxide (TiO2). The aim of this study was to evaluate the effect of TiO2 nanoparticles on the setting time, working time, push-out bond strength and compressive strength of MTA. Material and methods The physical properties to be evaluated were determined using the ISO 6786:2001 and 9917 specifications. Fifteen samples of each material (MTA or MTA with 1% weight ratio of TiO2 Nanoparticles) were prepared for any evaluated physical property. Data were analyzed using descriptive statistics and T-test. Statistical significance was set at P Res…