The paper presents influence of diverse shapes and dimensions of carbon nanostructures on physical properties of polymer composites. Graphene nanoplatelets, carbon nanotubes, graphite nanofibers, and graphite microflakes have been investigated as fillers in polymethacrylate resin. Layers were deposited with printing techniques used in printed electronics technology such as screen printing and spray coating, both elaborated in our earlier works. Different sets of measurements have been performed for obtained layers with particular carbon nanofillers. Thickness and topography have been examined using optical profilometer. Morphology of nanostructures has been observed with scanning electron microscope. Moreover, sheet resistivity and optical transmission in visible wavelength have been measured. Also mechanical properties have been characterized for each polymer composite by conducting fatigue test which consisted of multiple bending cycles.
The paper presents results of the studies concerning aluminum-graphene composites produced with use of step technique; first mechanical alloying of Al and graphene powders and later intensive deformation by the high pressure torsion. As a result small, thin and round samples of composites, about 10 mm in diameter were achieved. For comparison similar samples not containing graphene were investigated. The X-ray diffraction, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy were applied to study composites structures and analyze graphene content and atomic bonds. The Raman spectroscopy method suggested multilayer graphene, which could also be identified as the defected nano-graphite as a component of the composite structure as well as some small content of the aluminum carbides. The highly dispersed microstructures of aluminum matrices were identified with the transmission electron microscopy, showing difference between the samples produced with the increased number of rotations, leading to the increased deformation realized. This method revealed carbon and aluminum oxides in large amounts which is interpreted as a surface effect. This method suggested also formation of the carbon-metal and carbon-metal- oxygen atomic bonds, which might partially result from formation of the carbides.
The investigation of influence of Xe^{+} ions irradiation of graphite on its surface topography and wettability was conducted. With the increase of the irradiation dose, the roughness average increases rapidly at first (when the sample was irradiated at the dose of 1 × 10^{14} cm^{-2}) and then decreases slowly. The atomic force microscopy three-dimensional pictures showed that after irradiation of graphite of Xe^{+} ions with a dose of 3 × 10^{15} cm^{-2} hemispherical grains (from 0.2 to 0.8 μm in diameter) appear on its surface. Surface water contact angle measurement showed that irradiation of graphite by Xe^{+} ions leads to a hydrophobic surface of graphite. We have observed that irradiation of graphite by Xe^{+} ions can be used for obtaining graphite surface with desirable topography and water wettability.
Mixed silicon/graphite anode materials were produced via mechanical milling process. The morphologies of mixed powders and electrodes were characterized via scanning electron microscopy and X-ray diffraction pattern. Electrochemical tests were performed by coin-type (CR2016) test cells. The cells were cyclically tested on a battery tester, and discharge capacities of produced anode materials were investigated with using constant current 300 mA/g over a voltage range of 80 mV-1.2 V.
This study is concerned with the research and development in the field of materials science, leading to the industrial applications especially for the development of materials by moulding process. The purpose of this study was to determine the influence of vanadium on microstructural, mechanical and electrochemical properties of gray cast iron with lamellar graphite EN-FGL250. We investigated the effect of adding element (vanadium), during the casting of the metal in the mould, in a powder form having a particle size of 0.5 mm with the amounts of 1%, 3% and 5% in weight percent on microstructural and mechanical properties of gray cast iron with lamellar graphite. The originality of this work is the addition of the vanadium powder during the last stage of cooling of the melted gray cast iron EN-FGL250. These additions have a significant impact on the solidification phenomenon since the deposited vanadium powder into the sand moulds creates the new sites of nucleation and absorbs a lot of heat leading to the fast cooling. From the experimental results, we can confirm that the cooling rate directly affects the microstructural, mechanical and electrochemical behavior of the cast gray iron treated with vanadium. As result, it was observed that there is a slight decrease of the elasticity modulus of the work pieces, and a reduction of the maximum tensile resistance R_{m}. Finally, the addition of vanadium considerably reduces the corrosion current of gray cast iron treated with vanadium.
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