Search results for "Tecnologie"

Computer Aided Design of an Effective Fixture for FSW Processes of Titanium Alloys

2011

During the last years welded titanium components have been extensively applied in aeronautical and aerospace industries because of their high specific strength and corrosion resistance properties. Friction Stir Welding (FSW) is a solid state welding process, currently industrially utilized for difficult to be welded or “unweldable” aluminum and magnesium alloys, able to overcome the drawbacks of traditional fusion welding techniques. When titanium alloys are concerned, additional problems arise as the need for very high strength and high temperature resistant tools, gas shield protection and high stiffness machines. Additionally, the process is characterized by an elevated sensitivity to te…

Formability of friction stir welding AZ31 magnesium alloy sheets

2010

Friction Stir Welding of Magnesium Alloys under Different Process Parameters

2010

Tool Geometry in Friction Stir Welding of Magnesium Alloy Sheets

2009

Mechanical and Microstructural modifications induced by Friction Stir Welding and Processing on AA5754 Aluminum Alloys

2011

Utensile di saldatura per attrito

2009

On the fem simulation of FSW and LFW operations

2010

Design of the friction stir welding tool using the continuum based FEM model

2006

In friction stir welding (FSW), the welding tool geometry plays a fundamental role in obtaining desirable microstructures in the weld and the heat-affected zones, and consequently improving strength and fatigue resistance of the joint. In this paper, a FSW process with varying pin geometries (cylindrical and conical) and advancing speeds is numerically modeled, and a thermo-mechanically coupled, rigid-viscoplastic, fully 3D FEM analysis able to predict the process variables as well as the material flow pattern and the grain size in the welded joints is performed. The obtained results allow finding optimal tool geometry and advancing speed for improving nugget integrity of aluminum alloys.

Surface processes in selective photocatalytic oxidation of hydroxybenzyl alcohols by TiO2 P25

2023

Aryl aldehydes and acids are important industrial intermediates, but their synthesis from the corresponding alcohols often requires the use of high temperatures and harmful solvents and oxidant agents. Heterogeneous photocatalysis represents an interesting option for the partial oxidation of alcohols to aldehydes at room temperature using water as solvent. In this work, the partial photocatalytic oxidation of 2-hydroxybenzyl alcohol (salicyl alcohol) and 4-hydroxybenzyl alcohol to the corresponding aldehydes and acids has been compared, under environmental-friendly conditions, employing TiO2 P25 as photocatalyst in water. The selectivity to the corresponding aldehydes and acids, under the s…

Surface characterization of metal ions loaded TiO2 photocatalysts: structure-activity relationship

2004

Transition metal loaded TiO2 powders were characterised and tested for the photodegradation of some organic acids. Both Lewis and Brønsted surface acid sites were present in the samples containing large amounts of Mo, V and W. The Brønsted sites are associated to the presence of the transition metals as they do not exist in the unloaded support, and in particular to the presence of these metals in high oxidation states. The trend of the pzc values of the various powders matches rather well both with the surface acidity of the samples experimentally determined by NH3 adsorption and with a scale of acidity/basicity for bulk binary oxides. XPS investigation indicates that only the presence of …