Search results for "visual_art"
showing 10 items of 2987 documents
Improvement of flame spraying PEEK coating characteristics using lasers
2011
Flame spraying is frequently used for PEEK coatings elaboration on metallic surfaces. However, this process has a certain number of limitations particularly considering the quality of the coatings like high porosity or low interfacial adherence. For that reason a thermal post-processing is often necessary. From all of the processes which can be used (flame, oven, etc.), laser can be an interesting technology. Then, the aim of this study is to analyse the dependence of the morphological structure (compactness) and the adherence of the flame sprayed PEEK coatings to the stainless steel (304L) and aluminium alloy (AA2017) substrates on laser parameters. Moreover, the influence of the laser bea…
Formation of calcium containing minerals in the low temperature dolomite ceramics
2011
In order to elaborate low temperature dolomite ceramics, potentially suitable for the production of building materials, local low carbonate clay and dolomite siftings were used as a raw materials. Relationship between mechanical properties, mineral composition and firing temperature kept in the range of 600-800° C were established. According to the obtained data it was detected that the optimal burning temperature, giving the highest crushing strength (40 MPa) was around 700-750° C, optimal proportion of dolomite and clay expressed as ratio between CaO and Al2O3 - 2.5 wt%. Gradual formation of C3A occurs during firing, yielding C4AHX, i.e. mainly C4AH13 after hydratation of obtained composi…
Effect of additives on the crystallization of cordierite-based glass-ceramics as glazes for floor tiles
2003
Abstract The effect of several additives such as fluxes and/or nucleants on a parent glass with composition located in the primary field of cordierite within the quaternary system CaO–MgO–Al 2 O 3 –SiO 2 has been examined. Crystallization path of glasses was determined by differential thermal analysis (DTA) and X-ray powder diffraction (XRD). Pressed pellets of powdered glasses containing different additives were submitted at thermal treatments up to 1200 °C. The microstructural development at several temperatures was followed by field emission scanning electron microscopy and energy-dispersive X-ray analysis. The results shown that additions of TiO 2 as nucleant and/or B 2 O 3 as flux to a…
The Structural, Microstructural, Mechanical and Dielectric Properties of the Li0.1Na0.9NbO3Ceramics
2011
Polycrystalline samples of Li0.1Na0.9NbO3 were obtained by means of a conventional ceramic technology. The analysis of the X-ray diffraction pattern showed the formation of single perovskite phase with an orthorhombic structure at room temperature. The EDS and EPMA measurements revealed that the sample is perfectly sintered, chemically homogeneous and confirmed its high quality. Elastic constants: Youngs's modulus E, shear modulus G and Poisson ratio ν were determined using an ultrasonic method. The dielectric measurements were performed in heating and cooling processes. It was found that a Li-doping influence dielectric properties. The obtained results indicated that Li0.1Na0.9NbO3 is a pr…
Moisture absorption by epoxy/montmorillonite nanocomposite
2009
The peculiarities of moisture absorption of epoxy–nanoclay composite are estimated in the paper. Second Fick’s law of diffusion was used to predict moisture diffusivity and equilibrium moisture content using accelerated analytical procedure. It was experimentally confirmed that sorption process in NC passes more slowly than in pure epoxy resin, for the highest filler content diffusivity reduces about half of diffusivity as for epoxy resin. The deviation from mixture rule was obtained for the equilibrium moisture content and the estimation of interphase content in composite was undertaken. It was determined that the higher content of interphase consistently leads to greater moisture absorpti…
Moisture Effects on Patch Bonded Composite Repairs
2016
The present work investigated the effects of moisture absorption on the residual tensile strength of unnotched, notched and double-patch repaired carbon/epoxy composites. Patches were bonded to the parent plate using Araldite2015 adhesive. Specimens were aged in demineralised water at 70°C and tested at moisture content of 0% (dry), 3%, 6% and 7%. Results showed that upon ageing, a maximum of 11% and 17% of strength reduction was found in unnotched and repaired specimens, respectively. On the contrary, a maximum of 15% increment in strength was observed in notched specimens. In addition, good fits to the experimental data were found using the proposed residual strength model, with the maxim…
Sorption properties of torrefied wood and charcoal
2014
AbstractPre-treating biomass by torrefaction is assumed to improve the material's storage properties because of reducing hydrophilicity. In order to assess the effect of sorption on storage properties, the adsorption of water vapour and capillary absorption of liquid water in torrefied and charred spruce and birch were studied. In addition, the chemical changes were evaluated through Fourier Transform Infrared (FT-IR) spectroscopy. Adsorption decreased notably as severity of treatment increased, as was expected due to degradation of the wood constituents, namely hemicelluloses and amorphous cellulose. Capillary absorption increased with increasing severity in spruce samples while birch show…
Fluoride-induced precipitates on enamel surface and subsurface areas visualised by electron microscopy and confocal laser scanning microscopy
1997
The present study examined the enamel surface after in vitro topical treatments with a neutral 2% NaF solution. For minimising the risk of artefacts, samples were inspected without pre-treatment as fresh, naturally wet specimens by complementary techniques: variable pressure electron microscopy (VP-SEM) and confocal laser scanning microscopy (CLSM). VP-SEM provided information on the surface morphology, whereas CLSM allowed non-destructive visualisation of subsurface areas. Neutral NaF solutions induced globular precipitates on the enamel surfaces. If the globules formed may be described as "calcium fluoride like material", the additional information of this experiment is that, after intera…
Rheological properties and morphology in LLDPE and PC based blends
1990
Abstract During an interlaboratory project on polymer blends (Technical Working Party-Polymer Blends-VAMAS), the rheological characteristics of some samples of blends of polycarbonate with linear low density polyethylene have been evaluated with the aid of a capillary rheometer. Some morphological observations on the extruded samples have also been performed through SEM and an attempt has been made to correlate the macroscopic and microscopic results.