Search results for "Aluminium"

Optimization of the sheet hydroforming process parameters to improve the quality of reshaped EoL components

2023

Abstract. The reshaping of End-of-Life (EoL) components by means of sheet metal forming process has been considered largely attractive, even from the social and economic point of view. At the same time, EoL parts can be often characterized by non-uniform thicknesses or alternation of work-hardened/undeformed zones as the results of the manufacturing process. Such heterogeneity can hinder a proper reshaping of the EoL part and residual marks on the re-formed blanks can be still present at the end of the reshaping step. In a previous analysis, the authors evaluated the effectiveness of reshaping a blank with a deep drawn feature by means of the Sheet Hydroforming (SHF) process: it was demonst…

Der austausch des cyclopentadienylliganden im methylcyclopentadienyl-mangantricarbonyl

1981

Abstract The exchange of the cyclopentadienyl ring in methylcyclopentadienylmanganese(I) tricarbonyl by methy-substituted benzenes in the presence of aluminium halide leads to [arene-Mn(CO) 3 ] + -ions. The reaction conditions have been optimised; in addition to the yield the purity of the complexes has been determined in some detail. After mild decomposition the arenes were analysed by GLC. Pure [arene-Mn(CO) 3 ] + -ions can be isolated with benzene, toluene, m - and o -xylene.

Study of voltage decrease in organic light emitting diodes during the initial stage of lifetime

2016

Abstract We report the results of lifetime DC testing at constant current of not-encapsulated organic light emitting diodes (OLEDs) based on Tris (8 idroxyquinoline) aluminum (Alq3) as emitting material. In particular, a voltage decrease during the initial stage of the lifetime test is observed. The cause of this behavior is also discussed, mainly linked to initial Joule self-heating of the device, rising its temperature above room temperature until thermal equilibrium is reached at steady state.

Molecular dynamics simulations of the nano-scale room-temperature oxidation of aluminum single crystals

2005

The oxidation of aluminum single crystals is studied using molecular dynamics (MD) simulations with dynamic charge transfer between atoms. The simulations are performed on three aluminum low-index surfaces ((1 0 0), (1 1 0) and (1 1 1)) at room temperature. The results show that the oxide film growth kinetics is independent of the crystallographic orientation under the present conditions. Beyond a transition regime (100 ps) the growth kinetics follow a direct logarithmic law and present a limiting thickness of 3 nm. The obtained amorphous structure of the oxide film has initially Al excess (compared to the composition of Al2O3) and evolves, during the oxidation process, to an Al percentage …

Oxidative degradation properties of Co-based catalysts in the presence of ozone

2007

Four series of cobalt-based catalysts, such as bare Co3O4 and CoO, CoOx-CeO2 mixed oxides, CoOx supported over alumina and alumina-baria and CoMgAl and CoNiAl hydrotalcites have been synthesized and investigated for the oxidative degradation of phenol in the presence of ozone. Characterizations were obtained by several techniques in order to investigate the nature of cobalt species and their morphological properties, depending on the system. Analyses by XRD, BET, TPR, UV-visible diffuse reflectance spectroscopy and TG/DT were performed. The CoNiAl hydrotalcite exhibits, after 4 h of reaction, the highest phenol ozonation activity followed by Co(3 wt%)/Al2O3-BaO and CoMgAl. The samples Co(1 …

Importance of iron and aluminium in rapid and slow combustion of peat

1990

Abstract The effects of Fe and Al on peat combustion and the formation of nitrogen oxides were studied under conditions of rapid combustion in an entrained flow reactor, and under conditions of slow combustion in a thermobalance and a differential scanning calorimeter. Iron had a strong catalytic effect on both the slow and rapid combustion, and it decreased the ratio of N2O to NO in the combustion gases. A decrease in the content of inorganic compounds decreased reactivity, probably because of the decrease in iron content. Aluminium did not have a detectable catalytic effect on the combustion rate but it depressed the formation of nitrogen oxides slightly. The chemical treatment to increas…

Photoelectrochemical study on anodic aluminum oxide films. Internal photoemission processes at the metal-oxide interface

1991

A photoelectrochemical investigation has been carried out on aluminum oxide films grown anodically at constant rate up to different thicknesses. Depending on the potential both anodic and cathodic photocurrents were observed at photon energies well below the optical bandgap expected for these layers. This finding is explained with the presence of internal photoinjection processes both for electrons and holes from the base metal into the oxide film. The analysis of the photocurrent spectra has given the threshold energies for both processes. The effect of the image force at the metal/oxide interface has been taken into account in order to derive the mobility gap of the films and the energeti…

1993

Langmuir-Blodgett films from a polymer with triphenylene moieties in the side groups deposited on a quartz substratum with aluminium and gold electrodes show a dark conductivity in the plane of the Langmuir-Blodgett film. This dark conductivity is increased using gold electrodes as compared with aluminium electrodes. It depends in a superlinear way upon the applied electric field and is not enhanced by oxygen. The dark conductivity can be enhanced by doping the Langmuir-Blodgett films with iodine but it is not influenced by doping the Langmuir-Blodgett films with 2,4,7-trinitro-9-fluorenone. Upon excitation in the absorption band of the triphenylene moiety an in-plane photocurrent, which is…

Growth and Characterization of Anodic Films on Al-Nb Alloys

2006

Abstract The anodizing behaviours of sputtering-deposited aluminium, niobium and Al-Nb alloys, containing 0.4, 7.5, 21, 40 and 55 at.% niobium, have been examined in 0.1 M ammonium pentaborate electrolyte with interest in the morphology, structure and electronic properties of the anodic oxides. Transmission electron microscopy revealed amorphous oxides, containing units of Nb2O5 and Al2O3, with formation ratios intermediate between those of anodic alumina and anodic niobia. Photocurrent spectroscopy provided increased understanding of the electronic properties of the anodic films, suggesting the formation of “mixed oxides” with insulating behaviours. The estimated band gap values are correl…

Chemical surface ageing in ambient conditions of an Al–Fe–Cr approximant phase.

2007

International audience; The γ -Al65Cr27Fe8 phase is a complex metallic alloy with interesting electrochemical properties. Here we present a detailed study of the surface ageing of this alloy when exposed to ambient conditions for a long time. A combination of x-ray reflectivity, photoemission spectroscopy and secondary neutral mass spectroscopy measurements is used to provide a model of the modification of the surface structure and its composition as functions of ageing time. The near surface structure is described by the stacking of three layers. The first layer on top of the substrate corresponds to a mixed metal oxide and is amorphous. The intermediate layer consists of pure aluminum oxy…