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High-grade concrete using nanoparticles
Labaj, Martin ; Bodnárová, Lenka (referee) ; Hela, Rudolf (advisor)
The aim of this paper is to summarize and assess the possibility of using nanoparticles as additives in high performance concrete. These particles have the ability to improve the mechanical and physical properties of cement composites or even gave them brand new ones. Industrial use, however, is hampered by several obstacles. In particular, it is the task of effective incorporation of nanoparticles into the matrix, the health and environmental risks and, last but not least, the financial costs. The experimental part of the work deals with the first-mentioned problem, namely with dispersing carbon nanotubes in aqueous solution and their subsequent integration into the structure of cement mortar.
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Carbon nanotubes in building materials
Fialová, Barbora ; Bayer, Patrik (referee) ; Rovnaník, Pavel (advisor)
Carbon nanotubes (CNTs) has become of great interest for scientists in many disciplines. This study examines the effect of CNTs as nanosized reinforcement for metakaolin–based geopolymer. It was found out that the addition of CNTs considerably affects the compressive and flexural strength geopolymer samples. The influence of CNTs on microstructure was examined using mercury intusion porosimetry and scanning electron microscopy.
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Determination of reference values of element contents in certified reference material SWCNT-1 by INAA a PGAA
Kučera, Jan ; Sturgeon, R. E. ; Grinberg, P. ; Oflaz, R. ; Paul, R. L. ; Bennett, J. W. ; De Nadai Fernandes, E. A. ; Kubešová, Marie ; Bacchi, M. A. ; Stopic, A. J.
Instrumental neutron activation analysis with both relative and k-0 standardization was used in four experienced laboratories to determine element mass fractions in single-wall carbon nanotube certified reference material (CRM) SWCNT-1. Results obtained were evaluated using the NIST “Type B On Bias” approach and yielded consensus values in agreement with NRCC certified values for Fe, Co, Ni and Mo and provided mass fraction values for thirteen additional elements, namely Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Br, La, W and Au. In addition, prompt gamma neutron activation analysis was employed to determine mass fractions of H, B, Co, Ni, and Mo. Results of this work provide a basis for the establishment of reference values of element mass fractions in CRM SWCNT-1, thus expanding its usability for more accurate characterization and benchmarking of similar nanotechnology materials.
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Synthesis of carbon nanotubes in mw plasma torch with different methods of catalyst layer preparation and their applications
Zajíčková, L. ; Jašek, O. ; Synek, P. ; Eliáš, M. ; Kudrle, V. ; Kadlečíková, M. ; Breza, J. ; Hanzlíková, Renáta
The microwave plasma torch (2 45 GHz) was used for the synthesis of carbon nanotubes from the mixture of CH4/H-2/Ar or C2H2/H-2/Ar on different substrates with iron catalyst Iron catalyst was prepared by vacuum evaporation of iron on Si, Si/SiOx or Si/AlxO(Y) substrates or by deposition of iron oxide nanoparticles on Si/SiOx substrate by decomposion of Fe(CO)(5) in gas feed Such prepared substrates were used for growth of carbon nanotubes. Recostruction of the iron catalyst layer into nanoparticles was also studied in dependence on substrate buffer layer, gas atmosphere and temperature Samples were studied by scanning and transmission electron microscopy and Raman spectroscopy. Synthesis resulted in rapid growth of MWNTs on all samples but the density, purity and nanotube diameter distribution varied Such prepared carbon nanotube layers were used for sensing applications.
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Depozice a zpracování uhlíkových nanotrubek připravených metodou PECVD za atmosférického tlaku
Kučerová, Z. ; Zajíčková, L. ; Jašek, O. ; Eliáš, M. ; Synek, P. ; Matějková, Jiřina ; Rek, Antonín ; Buršík, Jiří
Carbon nanotubes (CNTs) were synthesized by plasma enhanced chemical vapor deposition from mixture of argon, methane and hydrogen using microwave plasma torch at atmospheric pressure. Nanotubes grew on a complex substrate system consisting of silicon wafer, buffer layer and thin catalytic iron film. As confirmed by scanning electron microscopy (SEM), this deposition technique produces bundles or ropes of nanotubes covered by crust composed of catalytic particles, amorphous carbon and other impurities such as fullerenes or other carbon nanoparticles. Because many scientific and technological applications, as well as characterization techniques require individual nanotubes a great attention has to be paid to the post-deposition processing of the deposit. The nanotube bundle could be separated by ultrasonication of the deposit in organic or inorganic liquid. Most commonly used liquids are water or ethanol.
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Depozice uhlíkových nanotrubek metodou depozice z plynné fáze s asistencí plazmatu
Jašek, O. ; Eliáš, M. ; Zajíčková, L. ; Kučerová, Z. ; Kudrle, V. ; Matějková, Jiřina ; Rek, Antonín ; Buršík, Jiří
Carbon nanotube properties provoked interest in many fields of application but there is still need to develop deposition techniques, which enable precise control of nanotubes positioning, alignment and properties. Chemical vapor deposition (CVD) methods and lately also plasma enhanced CVD (PECVD) are most promising to reach this goal. In the first part of the article we will briefly describe carbon nanotubes structure and properties and review the necessary conditions and possible control mechanisms used in PECVD deposition method. In the second part, examples of two deposition techniques, one working at a low pressure and one at an atmospheric pressure, will be described and reached results analyzed.
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