Search results for "Aluminium"
showing 10 items of 548 documents
Influence of the feed per tooth variation on the surface roughness at end milling of an aluminum alloy
2019
Abstract As a part of the cutting process, a researched aspect continuously is surface quality. Based on and using the results of previous research, the present scientific paper addresses the problem of the machined surfaces roughness. The cutting process approached in this study is the end-milling one, and the workpiece material used to carry out the study is the aluminum alloy used in the aerospace industry. The adopted cutting regime imply to keep the cutting speed at a constant value while the cutting parameters: cutting depth and feed per tooth vary with different values. The experimental research carried out by the authors in a prestigious industrial company is complicated and complie…
Investigation of Effective Thermal Conductivity Aluminum Foams
2012
Abstract The study on the heat transfer mechanisms through the aluminium foam with a fluid in void cells of that foam was reported in this paper. Based on laboratory experiments, the effective thermal conductivity coefficient values were found for various type aluminum foams which had been filled up with a gas or a liquid. The significant effects were observed from porosity as well as from metal and fluid properties on the heat transfer capacity in a foam-fluid system. The convective heat transfer phenomenon was identified to occur in the foam cellular space. That phenomenon affected the effective thermal conductivity much more for liquid-filled foams than for gas-filled foams.
Efficient growth of sub-micrometric MOF crystals inside the channels of AAO membranes
2013
International audience; A dynamic step-by-step methodology has been implemented to grow the HKUST-1 porous coordination polymer inside commercial anodic aluminium oxide membranes. Efficient crystal growth is achieved from the membrane inner walls and over the whole membrane thickness when copper acetate colloidal suspensions and benzene tricarboxylic acid solutions are forced to flow through the membrane. Sorption properties of the HKUST-1 embedded in membranes show selectivity for CO2 over CO, CH4, O2 and N2 similar to the bulk material.
300°C SiC Blocking Diodes for Solar Array Strings
2009
Silicon Carbide 300V-5A Ni and W Schottky diodes with high temperature operation capability (up to 300°C) have been fabricated. This paper reports on the stability tests (ESA space mission to Mercury, BepiColombo requirements) performed on these diodes. A DC current stress of 5A has been applied to these diodes at 270°C for 800 hours. These reliability tests revealed both, degradation at the Schottky interface (forward voltage drift) and at the diode top surface due to Aluminum diffusion (bond pull strength degradation). The use of W as Schottky metal allows eliminating the forward voltage drift producing stable metal–semiconductor interface properties. Nevertheless, SEM observations of the…
Cutting Conditions and Work Material State Identification through Acoustic Emission Methods
1992
Summary This paper examines the problem of in-process monitoring of metal cutting operations carried out on aluminum alloys for aeronautical applications. Turning tests were conducted on annealed and heat treated aluminum alloy bars, using carbide tools. For both work material conditions, different combinations of cutting parameters were used. During cutting tests, acoustic emission (AE) and cutting force sensor data were detected and processed. The comparison between AE responses from the annealed and heat treated aluminum alloys allowed, with the help of force sensor data, to verify the applicability of AE and sensor fusion techniques for in-process and real time identification of work ma…
On tool stirring action in friction stir welding of work hardenable aluminium alloys
2013
In the paper solid state bonding conditions obtained in friction stir welding (FSW) of AA5754-H111 butt joints are analysed, considering the so called zigzag line in the transverse section of the joints. A wide experimental campaign was carried out varying both tool advancing speed and tool rotational one. The effects of the process on the mechanical properties of the joint were highlighted and micro- and macro-observations were used in order to explain the reasons of the enhanced mechanical properties found for the welded material. Numerical results derived from a FEM model previously developed by the authors were utilised to point out the different mechanical and metallurgical behavior of…
Experimental and Numerical Study on Linear Friction Welding of AA2011 Aluminum Alloy
2014
Linear Friction Welding (LFW) is a solid-state joining process used for non-axisymmetric components. LFW involves joining of materials through the relative motion of two components undergoing an axial force. In the process, the heat source is given by the frictional forces work decaying into heat and determining a local softening of the material and eventually the needed bonding conditions. In the paper, an experimental and numerical campaign is proposed for AA2011 aluminum alloys welding. Different case studies are considered with fixed oscillation frequency and varying pressure at the interface between the specimens. Constant oscillation amplitude and specimens geometry is used. The calcu…
Outlining the Limits of Friction Stir Consolidation as Used as an Aluminum Alloys Recycling Approach
2021
Friction stir consolidation (FSC) is a solid-state process that recycles metal scraps economically and eco-friendly compared to the conventional melting method. The process parameters especially processing time and rotational speed, have a crucial role in achieving a sound disc during FSC. The current study answers the research question of how far these process parameters can be effective when the mass of chips to be recycled increases. In specific, an experimental setup was analyzed that was previously identified as challenging for recycling 20 g chips of aluminum alloy AA 2024-O. Rotational speed was set doubled, and processing time was increased up to 1.5 times of their initial values. T…
Mechanism of aluminium incorporation into C–S–H from ab initio calculations
2014
Blended cements have great potential to reduce the CO2 footprint due to cement production. C(alcium)–S(ilicate)–H(ydrate) in these novel materials is known to incorporate a considerable amount of Al. We have for the first time applied large-scale first principles calculations to address the mechanism of Al incorporation into low C/S ratio C–S–H. In agreement with state-of-the-art NMR information, our calculations show that Al substitutes Si in bridging tetrahedra only, and that substitutions in pairing tetrahedra are strongly disfavoured in a wide range of conditions. In broad terms, the energy penalty for having an Al atom in a pairing position is of about 20 kcal mol−1. Al in bridging tet…
EXAFS studies on the local structure of Er3+ ions in silica xerogels co-doped with aluminium
2001
The local environment around Er3+ ions in wet and densified (at 900°C) silica xerogels (pure and co-doped with aluminium) has been studied at the Er L3-edge by X-ray absorption spectroscopy using the fluorescence detection technique. The radial distribution functions (RDF), reconstructed from X-ray absorption fine structure (EXAFS), show several changes in the local co-ordination of erbium ions upon densification: shortening of the Er-O and Er-Si/Al distances, decrease of the co-ordination numbers and broadening of the Er-O RDF. The effect of Al co-doping is clearly discerned by EXAFS in both the first and second co-ordination shells for densified gels and mainly in the second shell for wet…