Search results for "Titanium"

RIDUZIONE FOTOCATALITICA DI CO2 IN SISTEMI GAS-SOLIDO IN PRESENZA DI TiO2 PURO E DROGATO CON RAME

2012

Advanced FEM modeling of friction stir welding of Ti6Al4V: Microstructural evolutions

2013

Friction Stir Welding (FSW) is a solid state welding process patented in 1991 by TWI; initially adopted to weld aluminum alloys, is now being successfully used also for high resistant materials. Welding of titanium alloys by traditional fusion welding techniques presents several difficulties due to high material reactivity resulting in bonding with oxygen, hydrogen, and nitrogen with consequent embrittlement of the joint. In this way FSW represents a cost effective and high quality solution. The final mechanical properties of the joints are strictly connected to the microstructural evolutions, in terms of phase change, occurring during the process. In the paper a 3D FEM model of the FSW wel…

Effect of process parameters on the joint integrity in Friction Stir Welding of Ti-6Al-4V lap joints

2013

Material flow analysis in dissimilar friction stir welding of AA2024 and Ti6Al4V butt joints

2016

The complex material flow occurring during the weld of dissimilar AA2024 to Ti6Al4V butt and lap joints was highlighted through a dedicated numerical model able to take into account the effects of the different materials as well as the phase transformation of the used titanium alloy.

Researches Regarding the Usage of Titanium Alloys in Cranial Implants

2014

In the last few decades, the concept of flexible manufacturing has started to gain more and more attention, as an adaptation of production methods to the increasingly varied demands by customers. Therefore, new procedures have been introduced as alternatives to the classical ones, a very promising one being incremental forming [. A possible application for this new procedure, targeted by the authors of this paper, is the manufacturing of custom-shaped prosthetic parts for use in various areas of human medicine. Such prostheses can have a functional role, when they target the replacing of a functional component of the human body, or an esthetic role, when they target the solving of problems …

Effect of silver deposits on the photocatalytic activity of titanium dioxide samples for the dehydrogenation or oxidation of 2-propanol

1991

Abstract Until now, the effect of the deposition of metal particles onto a powdered semiconductor oxide on its photocatalytic activity has been determined for group VIII transition metals only. In this study, AGTiO2 samples were prepared by photodeposition, characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) and tested, under band-gap illumination, using the oxidation of 2-propanol (neat liquid phase or mixed with water) in the absence or presence of molecular oxygen. The silver deposits were found to be metallic both before and after use, but the size of the particles and their distribution on the support were markedly influenced by the type …

Heterometallic Titanium-Organic Frameworks as Dual Metal Catalysts for Synergistic Non-Buffered Hydrolysis of Nerve Agent Simulants

2020

Heterometallic metal-organic frameworks (MOFs) can offer important advantages over their homometallic counterparts to enable targeted modification of their adsorption, structural response, electronic structure, or chemical reactivity. However, controlling metal distribution in these solids still remains a challenge. The family of mesoporous titanium-organic frameworks, MUV-101(M), displays heterometallic TiM2 nodes assembled from direct reaction of Ti(IV) and M(II) salts. We use the degradation of nerve agent simulants to demonstrate that only TiFe2 nodes are capable of catalytic degradation in non-buffered conditions. By using an integrative experimental-computational approach, we rational…

Catalytic Dehydration of Fructose to 5-Hydroxymethylfurfural in Aqueous Medium over Nb2O5-Based Catalysts

2021

The catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) in water was performed in the presence of pristine Nb2O5 and composites containing Nb and Ti, Ce or Zr oxides. In all experiments, fructose was converted to HMF using water as the solvent. The catalysts were characterized by powder X-ray diffraction, scanning electron microscopy, N2 physical adsorption, infrared and Raman spectroscopy and temperature-programmed desorption of NH3. Experimental parameters such as fructose initial concentration, volume of the reacting suspension, operation temperature, reaction time and amount of catalyst were tuned in order to optimize the catalytic reaction process. The highest selectivit…

Hybrid Organic-Inorganic Nanostructures Fabricated from Layer-by-Layer Self-Assembled Multilayers of Hyperbranched Polyglycerols and Phosphorus Dendr…

2007

Multilayer thin films of cationic phosphorous dendrimers and anionic hyperbranched polyglycerols were fabricated by electrostatic layer-by-layer (LbL) self-assembly (SA). The film formation was monitored by surface plasmon resonance (SPR) spectroscopy and UV-visible spectroscopy, and it was found that the stepwise, alternating deposition results in a linear growth up to four bilayers. Hybrid organic-TiO2 nanostructures were generated by exposing the supramolecular multilayers to TiCl4 precursors. The amounts of TiO2 incorporated inside the scaffolds could be tuned by controlling the porosity of the multilayers with the addition of a small amount of salts. The resulting hybrid films exhibit …

Solubility and microstructural development of TiO2-containing 3Al2O3·2SiO2 and 2Al2O3·SiO2 mullites obtained from single-phase gels

2007

Abstract The interdependence of the titanium oxide amount and the anisotropic growth of mullites prepared from single-phase gels were investigated. Gels with stoichiometries 3(Al2−xTixO3)·2(SiO2) and 2(Al2−xTixO3)·(SiO2), with 0 ≤ x ≤ 0.15 were prepared by the semialkoxide method. Gels and specimens heated at temperatures between 1200 and 1600 °C were characterized by using infrared spectroscopy (IR), X-ray diffraction (XRD) and transmission and field emission scanning electron microscopies (TEM and FESEM). Al2TiO5 as minor impurity was detected in both series of mullites for gel precursor compositions x = 0.10 and x = 0.15, obtained at temperatures between 1200 and 1600 °C. Variations of l…