Search results for "engineering.material"
showing 10 items of 2352 documents
Static and dynamic mechanical properties of Arundo Donax fillers-epoxy composites
2014
Abstract Aim of this work is to investigate the feasibility of using a natural and inexpensive filler obtained by grinding the culms of Arundo Donax as reinforcement of epoxy resins. The effect of the content and size of Arundo Donax fillers on static and dynamic mechanical properties was evaluated showing that the composites exhibit higher tensile moduli, comparable flexural moduli and lower strength properties in comparison to the neat resin. Moreover, changes in the storage and the loss moduli only above the glass transition temperature (i.e. in the rubbery region) were found while neither significant shifts of tan δ peaks to higher temperatures nor reductions in the peak height of the c…
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…
Iron Mineralogy of Venus' Surface Investigated by M�ssbauer Spectroscopy
2000
Abstract We discuss the use of Mossbauer (MB) spectroscopy to study Fe-bearing minerals on Venus' surface. At present, there is no direct information about the mineralogy of Venus' surface, although in situ chemical analyses by X-ray fluorescence (XRF) spectroscopy have been done by the Venera 13, 14, and Vega 2 spacecraft at three landing sites. The XRF elemental analyses are sensitive to major rock-forming elements heavier than sodium and show the presence of several mass percent iron. Normative mineralogical calculations model the Fe mineralogy at the Venera 13, 14, and Vega 2 landing sites, but the actual Fe minerals present are unknown. We calculate synthetic MB spectra for the normati…
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…
Whispering gallery mode resonators covered by a ZnO nanolayer
2020
Abstract The exceptional ability of whispering gallery mode resonators (WGMRs) to confine light within makes them interesting for sensing applications. The small size and high values of quality (Q) factors of the WGMR can be combined with a broad range of supporting optical elements. The surface of the resonator can be coated to enhance the desired attributes. In this paper, the impact of the ZnO layer thickness on the Q-factor of the WGMR has been studied. WGMRs were fabricated on a tip of a standard telecom fiber melted with an oxyhydrogen flame. The surface of the WGMR was coated with ZnO nanolayers of different thickness (5–100 nm) by atomic layer deposition (ALD). The Q-factor of as-pr…
Experimental investigation of effect of printing direction and surface roughness on the mechanical properties of AlSi10Mg-alloy produced by selective…
2021
The additive manufacturing has initially gained popularity for production of non-loadbearing parts and components or in the fields where the material strength and ductility are less important such as modelling and rapid prototyping. But as the technology develops, availability of metal additive manufacturing naturally dictates the desire to use the produced components in load-bearing parts. This requires not-only a thorough documentation on the mechanical properties but also additional and independent research to learn the expected level of variation of the mechanical properties and what factors affect them. The presented paper investigates strength, ductility, hardness, and microstructure …
High Performance Solar Blind Detectors based on AlGaN grown by MBE and MOCVD
2004
ABSTRACTSolar blind detectors based on AlGaN grown by Molecular Beam Epitaxy and Metal Organic Vapor Phase Epitaxy have been fabricated and characterized. Metal Semiconductor Metal (MSM) detectors and vertical Schottky detectors have been realized, with a design that allows back side illumination. The growth was optimized in order to improve the layer quality, avoid crack formation, and provide the best detector performance. The technological process was also optimized in order to reduce the dark currents and improve the spectral rejection ratio, which is a key factor for solar blind detection. As a result, a rejection ratio of 5 decades between the UV (below 300 nm) and 400 nm, and a steep…
Epitaxial thin films of intermetallic compounds
2002
Publisher Summary The potential of epitaxial thin films of intermetallic compounds in basic and applied research is emerging. Although the growth of semiconductor heterostructures and compounds based on molecular beam epitaxy (MBE) and related methods has come through a 30-year history of ongoing refinement and sophistication, still much has to be learned concerning the growth and characterization of even moderately complex metallic thin film structures. MBE represents a well-defined crystallization technique based on the reactions among molecular or atomic beams of the constituent elements on a substrate or template at elevated temperatures in an ultrahigh vacuum (UHV) environment. Owing t…
Experimental Research of the Formability of Lightweight Metallic Materials Used in Automotive Industry
2015
This paper aims to study the plastic deformation behaviour of lightweight metallic materials in order to reduce the total weight of the vehicles without affecting their performances. For the theoretical and experimental researches presented here, among these materials the AZ31B magnesium alloy has been chosen, a representative alloy for the magnesium-zinc-aluminium alloy system. The results of the theoretical researches, made on finite elements models, were validated by means of experimental researches consisting of tensile tests, forming limit curves determination tests and AZ31B magnesium alloy drawing, respectively.
A pulsed laser technique for an evaluation of the spall resistance of sputtered oxide films: diagnostic by interferometric probing
1998
Abstract A pulsed laser technique, based on conventional laser acoustics testing, has been developed to define the spall resistance of sputtered oxide films on a metallic target. Direct irradiation of the coated side of the sample generates an acoustic source at the inner film–metal interface. A model of the laser-induced epicentral displacements at the opposite side that takes into account the confining effect of the coating has been proposed to evaluate the critical laser irradiance corresponding to progressive damages at the inner film–metal interface, i.e. interface delamination, film spallation and film expulsion, respectively. The behavior of Al 2 O 3 and ZrO 2 films deposited by PVD …