Search results for "ALLOYS"
showing 10 items of 1689 documents
Microstructure-oxidation resistance relationship in Ti3AlC2 MAX phase
2020
International audience; Spark Plasma Sintering and Hot Isostatic Pressing were used to synthesize coarse-grained and fine-grained Ti3AlC2 specimens. Moreover, Spark Plasma Sintering processing parameters were modified in order to vary the TiC, Al2O3 and TixAly impurity and the porosity contents in the fine-grained samples. The influence of the Ti3AlC2 microstructure on the oxidation resistance was assesed. It is demonstrated that the grain size can drastically modify the oxidation resistance. The higher density of grain boundaries, in fine-grained specimens, increases the number of Al diffusion paths and leads to the formation of a protective alumina scale. In coarse-grained sample, Al diff…
Formation of anodic films on sputtering-deposited Al–Hf alloys
2009
Abstract The growth of barrier-type anodic films at high efficiency on a range of sputtering-deposited Al–Hf alloys, containing from 1 to 95 at.% Hf, has been investigated in ammonium pentaborate electrolyte. The alloys encompassed nanocrystalline and amorphous structures, the latter being produced for alloys containing from 26 to 61 at.% Hf. Except at the highest hafnium content, the films were amorphous and contained units of HfO 2 and Al 2 O 3 distributed relatively uniformly through the film thickness. Boron species were confined to outer regions of the films. The boron distributions suggest that the cation transport number decreases progressively with increasing hafnium concentration i…
Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media
2018
Inorganic nanotubes are attracting the interest of many scientists and researchers, due to their excellent application potential in different fields. Among them, halloysite and imogolite, two naturally-occurring aluminosilicate mineral clays, as well as boron nitride nanotubes have gained attention for their proper shapes and features. Above all, it is important to reach highly stable dispersion in water or organic media, in order to exploit the features of this kind of nanoparticles and to expand their applications. This review is focused on the structural and morphological features, performances, and ratios of inorganic nanotubes, considering the main strategies to prepare homogeneous col…
Energy structure and electro-optical properties of organic layers with carbazole derivative
2014
Abstract Phosphorescent organic light emitting diodes are perspective in lighting technologies due to high efficient electroluminescence. Not only phosphorescent dyes but also host materials are important aspect to be considered in the devices where they are a problem for blue light emitting phosphorescent molecules. Carbazole derivative 3,6-di(9-carbazolyl)-9-(2-ethylhexyl)carbazole (TCz1) is a good candidate and has shown excellent results in thermally evaporated films. This paper presents the studies of electrical properties and energy structure in thin films of spin-coated TCz1 and thermally evaporated tris[2-(2,4-difluorophenyl)pyridine]iridium(III) (Ir(Fppy)3). The 0.46 eV difference …
A modular approach towards functional supramolecular aggregates - subtle structural differences inducing liquid crystallinity.
2016
Herein we report an efficient modular approach to supramolecular functional materials. Hierarchical self-assembly of azopyridine derivatives and hydrogen-bond donors yielded discotic assemblies. Subtle differences in the core units introduced mesomorphic behaviour and fast photo-response of the liquid crystals based on phloroglucinol. The presented results prove the benefits of a modular methodology towards highly responsive materials with tailor-made properties.
Experimental Characterization of FSW T-Joints of Light Alloys
2007
Welding is playing a growing role in transport industry due to relevant advantages it allows. Friction Stir Welding is considered one of the most promising joining technologies, especially when it is applied to light alloys. Focusing attention on FSW of T-joints, several parameters have to be considered, and due to thermo-mechanical features of process, T joints need a dedicated approach. A set of previously developed experiments has shown that the tilt angle plays a relevant role in the joint strength. Furthermore it should be observed that T-joints are very often utilized in aerospace industries since the produced structures are composed of joined skins and stingers. Numerous data are rep…
Effect of driving method on the degradation of organic light emitting diodes
2003
Abstract Lifetime testing results are reported for organic light emitting diodes (OLEDs) having the structure ITO (anode)/ N , N ′-diphenyl- N , N ′-bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine (TPD)/tris-(8-hydroxyquinoline)aluminum (AlQ)/Al (cathode) and operated using dc and pulsed waveforms for comparison. In ambient atmosphere non-encapsulated devices show a lifetime of about 70 h in pulsed operation at an initial luminance of 500 cd/m 2 , almost four times longer than in dc operation. A fast initial decay of luminance is observed for dc operation. It is most probably due to a combination of Joule heating and mobile ionic impurities migration within the OLED structure under the conti…
Model network architectures in vitro on extracellular recording systems using microcontact printing
2001
A PDMS stamp is used to transfer a synthetic peptide in a given pattern to any suitable surface. Using this method two-dimensional neuronal model networks could be formed on glass substrates as well as on electronic devices and adjusted to the given microelectronic structure. The present work focuses on the mechanism of neurite guidance under simplified in vitro conditions, using in vitro guidance cues and outline the incorporation of these interfacial methods into microelectronic sensor devices.
A new gas sensor electronic interface with generalized impedance converter
2008
A new gas sensor conditioning circuit that allows a direct resistance-to-frequency conversion, as well as the procedure for the design, is presented. The generalized impedance converter (GIC) proposed is configured as a variable capacitor connected with the capacitor timing terminal of an astable multivibrator implemented by a PSoC (programmable system on chip) microcontroller device. The GIC effective input impedance, which is controlled by the gas sensor resistance, controls the astable output frequency. Good correlation of the experimental output frequency, which depends on the gas concentration, is achieved. The circuit is a simple gas sensor digital interface with frequency output.
Physical vapor deposition of Bi2S3 as absorber material in thin film photovoltaics
2013
Abstract In order to investigate alternative absorber materials for inorganic solar cells, thin films of bismuth trisulfide (Bi2S3) were deposited under high vacuum conditions by the thermal evaporation method from compound material. The effects of the substrate temperature during deposition on the structural, stoichiometric, optical and electrical properties were investigated. Polycrystalline thin films close to an ideal stoichiometry could be deposited for temperatures TSub = 80–290 °C; thereby a transition from rough needle-shaped particles with (hk0)-orientation parallel to the surface of the substrate towards block shaped grains with a preferred direction out of the surface could be ob…