Search results for "Composites"
showing 10 items of 1905 documents
STRUCTURE AND MAGNETIC PROPERTIES OF COBALT FERRITE PARTICLES PRODUCED BY METHOD OF PYROLYTIC SYNTHESIS
2008
ABSTRACT Magnetic fine particles of cobalt ferrite have been prepared by method of pyrolytic synthesis. X-ray diffraction confirmed the formation of single-phase cobalt ferrite nanoparticles in the range 6–50 nm. The size of the particles varies depending on matrix dispersity and mass content in the organic precursors. A large coercivity observed to be small for smaller single-domain particles due to superparamagnetic behavior.
Elucidating structural order and disorder phenomena in mullite-type Al4B2O9 by automated electron diffraction tomography
2017
The crystal structure and disorder phenomena of Al4B2O9, an aluminum borate from the mullite-type family, were studied using automated diffraction tomography (ADT), a recently established method for collection and analysis of electron diffraction data. Al4B2O9, prepared by sol-gel approach, crystallizes in the monoclinic space group C2/m. The ab initio structure determination based on three-dimensional electron diffraction data from single ordered crystals reveals that edge-connected AlO6 octahedra expanding along the b axis constitute the backbone. The ordered structure (A) was confirmed by TEM and HAADF-STEM images. Furthermore, disordered crystals with diffuse scattering along the b axis…
Investigation of AC Electrical Properties of MXene-PCL Nanocomposites for Application in Small and Medium Power Generation
2021
The paper examined Ti3C2Tx MXene (T—OH, Cl or F), which is prepared by etching a layered ternary carbide Ti3AlC2 (312 MAX-phase) precursor and deposited on a polycaprolactone (PCL) electrospun membrane (MXene-PCL nanocomposite). X-ray Diffraction analysis (XRD) and Scanning Electron Microscopy (SEM) indicates that the obtained material is pure Ti3C2 MXene. SEM of the PCL-MXene composite demonstrate random Ti3C2 distribution over the nanoporous membrane. Results of capacitance, inductance, and phase shift angle studies of the MXene-PCL nanocomposite are presented. It was found that the frequency dependence of the capacitance exhibited a clear sharp minima in the frequency range of 50 Hz to o…
Cation Distribution in a Titanium Ferrite Fe2.75Ti0.25O4Measured byin-SituAnomalous Powder Diffraction Using Rietveld Refinement
1998
Many ferrites contain different cations with various valence states and location in the spinel structure. In compounds such as these, only a combination of different techniques such as Mussbauer spectroscopy, IR analysis, and thermogravimetry allows the distribution of cations to be obtained. For very complicated distributions, the mathematical decomposition of derivative thermogravimetric curves (DTG) leading to quantitative distribution is uncertain. In this paper, we present an alternative technique based on resonant diffraction. The anomalous scattering of each cation in the crystalline material is used to determine its amount and position by Rietveld refinement. Since the energy for su…
Study of plastic deformation modes in zirconium by color image analysis
2004
Abstract Twinning, as a deformation mode, is a complement to slip. This paper deals with the study from a qualitative point of view, as well as from a quantitative one. Besides techniques widely used in materials science studies such as electron backscattered diffraction (EBSD) or X-ray diffraction (XRD), colour image analysis technique are presented here. Its results manage to confirm or complete the ones obtained, thanks to others methods.
Elastic Properties of Barium Zirconate Titanate Ceramics
2011
In the paper the influence of zirconium admixture on the structure and material constants of polycrystalline ferroelectric materials BaZrxTi1-xO3 (BZT) was examined. The barium zirconate titanate samples were prepared by a conventional solid state reaction method. A single phase with perovskite structure of the samples, was identified by an X-Ray diffraction technique at room temperature. The performed EDS study revealed that the samples were perfectly sintered and the material was chemically homogeneous. The dependence of shear modulus G on sample composition is similar to the respective dependence of Young's modulus E, whereas the Poisson's ratio ν decreases with the increase in zirconium…
Differential scanning calorimetry investigation of phase transition in $BaZr_{x}Ti_{1-x}O_{3}$
2009
ABSTRACT Lead-free BaZrxTi1-xO3 (x = 0; 0.025; 0.125) ceramics have been obtained by a conventional method. A single-phase perovskite structure of the ceramics was identified by the X-ray diffraction method. EDS analysis, performed for the individual grains of the tested sample, showed a good homogeneous distribution of all elements throughout the grains. The thermal behaviour of BaZrxTi1-xO3 (x = 0; 0.025; 0.125) ceramics was studied using the Differential Scanning Calorimetry (DSC). Measurements showed the influence of Zr addition on the character of phase transition in the BaTiO3 structure. The results were compared with these ones obtained for pure BaTiO3.
Sol-gel synthesis and photocatalytic activity of ZnO-SnO2 nanocomposites
2014
Abstract ZnO–SnO 2 nanocomposites were synthesized by a facile sol–gel synthesis route and characterized through X-ray diffraction, BET specific surface area analysis, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy. The photocatalytic activity of the samples was tested using the degradation of 4-nitrophenol under UV light as model reaction. The ZnO/SnO 2 molar ratio was varied in order to study its influence on the photoefficiency of the samples. The ZnO–SnO 2 nanocomposites showed higher photoactivity than the pure oxides and in particular the sample with ZnO/SnO 2 mol…
A DIC-based study of flexural behaviour of roving/mat/roving pultruded composites
2015
Abstract This paper reports a study of the flexural behaviour and resultant failure modes in E-glass/polyester pultruded composites. The digital image correlation (DIC) method is used to estimate the effect of fibre orientation on failure behaviour in thick beams, taking into account the presence of continuous filament mat layer (CFM) in the stacking sequence. In particular, the tests were carried out for specimens with off-axis angle of 0°, 7.5°, 15°, 30°, 45° and 90°. The crack initiation and the failure mechanisms depend on the mutual interaction between the stiffness properties of different areas in the stacking sequence. An influence index (I) was introduced to evaluate the magnitude o…
Experimental assessment of the shield-to-salt-fog properties of basalt and glass fiber reinforced composites in cork core sandwich panels applications
2018
Abstract In this paper, the effect of salt-fog exposition on the mechanical behavior of sandwich panels having cork agglomerate core was investigated. In particular, the aim of this research work is to assess the shield function of unidirectional basalt and E-glass reinforced polymer on the aging and failure mechanism of the core when such class of material are destined to operate in hostile environments (e.g., marine environment). To do this, the manufactured sandwich panels were exposed up to 60 days to salt-fog environment, according to ASTM B 117 standard. Unaged and aged specimens were analyzed through three point bending tests after aging time of 10, 25 and 60 days. Digital Image Corr…