Authors: Péter M. Nagy, P. Horváth, Gábor Pető, Erika Kálmán
Abstract: The nanoindentation behaviours of single crystalline silicon samples has gained wide attention in recent years, because of the anomaly effects in the loading curve, caused by the pressure induced phase transformation of silicon. To further enlighten the phenomenon bulk, ion-implanted, single crystalline Si samples have been studied by nanoindentation and by atomic force microscopy. The implantation of Si wafers was carried out by P+ ions at 40 KeV accelerating voltage and 80 ions/cm2 dose, influencing the defect density and structure of the Si material in shallow depth at the surface. Our experiments provide Young’s modulus and hardness data measured with Berkovich-, spherical- and cube corner indenters, statistics of the pop-in and pop-out effects in the loading- and unloading process, and interesting results about the piling-up behaviour of the Si material.
29
Authors: Péter Németh, Ágnes Csanády, Katalin Papp, Anna C. Pintér, László Szabó, Zoltán Pászti, Attila Lajos Tóth, Erika Kálmán
Abstract: Protective, chromate substitute thin layers on roughened galvanized surfaces produced at OCAS
(Arcelor, Belgium) were characterized and compared using Scanning Electron Microscopy
(SEM+EDS), Atomic Force Microscopy (AFM), Nanoindentation and X-ray Photoemission
Spectroscopy (XPS). EDX maps, line scans and point analyses obtained at various places of the
surfaces have shown differences between the CVD and silane nanolayers in the matter of thickness
distribution and composition. At cross-section specimens the thickness of the layers could be
shown. The hardness differences caused by layer thickness variations are hard to follow by
nanoindentation as the penetration depth of the indenter is much larger than the thickness of the
coatings. XPS measurements can distinguish between the chemical states of silicon in CVD and
silane coatings.
433
Authors: A. Paszternák, A. Pilbáth, Z. Keresztes, Ilona Felhősi, J. Telegdi, Erika Kálmán
Abstract: The layer formation of phosphonic acids on mica surface as a model system, from
aqueous and ethanol solutions has been investigated. The aggregation behavior (critical micelle
concentration, cmc) of molecules in the solution phase has been determined by surface tension
measurements in order to select the appropriate concentration for the layer formation experiments.
Layer formation of self-assembling molecules of alkyl-phosphonic acids has been followed by
atomic force microscopy (AFM). Nucleation, growth and coalescence of densely packed islands of
phosphonates from ethanol solution have been recorded on mica surface. The structure of islands
depends on the length of alkyl-chains. Self-assembly of phosphonates has been also observed from
aqueous solution, as presented by octyl-phosphonic acid (OcPA). The height of OcPA islands is
1.46 0.22 nm, which is practically equal with the length of molecule (1.4 nm). This shows that
OcPA molecules form monolayer height domains on the mica surface.
257
Authors: László Trif, Nikoletta Molnár-Vörös, Gyula Tolnai, István E. Sajó, Sándor Mészáros, Erika Kálmán
Abstract: New chemical synthesis procedure for the preparation of nickel zinc doped W-type
hexagonal barium ferrite and aluminium doped yttrium-iron garnet nanoparticles has been
developed, using the nitrate-citrate sol-gel auto-combustion method (NCSAM). The crystalline
phase attributes, microstructure, morphology, specific surface area, Curie temperature (TC),
permeability, thermal behavior of the as-burnt phase and the heat treated powders were
characterized using XRD, SEM, FT-IR, BET, TG-DTA and AC magnetic permeability with
frequency shift. In the case of the hexaferrite, the pure W-type ferrite phase is formed during 4 hour
annealing at a temperature of 1200 °C, the garnet phase is formed at a lower temperature i.e. 1000
°C. Furthermore it has been confirmed, that the AC magnetic permeabilities of the garnet materials
are strongly depending on the chemical composition.
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Authors: A. Pilbáth, É. Pfeifer, F.H. Kármán, Ilona Felhősi, J. Mink, Erika Kálmán
Abstract: The objective of our studies was to investigate the layer formation of 1, 5-diphosphonopentane
(DPP) on zinc surface from aqueous solution. For surface treatment, water based solutions
of 1, 5-diphosphono-pentane was applied with different treatment times. Evidence of the adsorption
of the diphosphonic acid on the zinc surface was obtained using the Infrared Reflection Absorption
Spectroscopy (IRRAS).
37
Authors: A. Gergely, J. Telegdi, Erika Kálmán
Abstract: In order to alter the physical/chemical characteristics of multi-walled carbon nanotubes (MWNTs)
we modified them by different organic reactions (Diels-Alder and Sand-Meyer reaction, oxidation)
and their d properties were characterized by thermogravimetry/mass spectrometry, photoelectron
spealterectroscopy, and nuclear magnetic resonance spectroscopy, as well as by dispersion. The
results proved that, depending on the groups built in the MWNTs, the modified carbon nanotubes
are more dispersible either in polar or apolar solvents and the suspensions are stable for long time.
The presence of the substituents in the MWNTs was proved by methods listed above, e.g. high
concentration of sulfur was detected when SO3H groups were inserted onto the MWNTs. The
enhanced thermal stability of the modified carbon nanotubes allows their further application.
623
Authors: Ágnes Csanády, László Ipacs, Gyula Kakuk, Erika Kálmán, Péter M. Nagy, Katalin Papp, István E. Sajó, András Szalay
Abstract: The aim of the present work is to produce new types of solid nanomaterials for different
purposes (coatings, fillers, foams, bulk pieces, etc.). Technologies such as RS Al flake
production, high energy mechanical milling and high energy rate forming technology (HERF)
for compacting are used. The products are analyzed mainly by XRD, SEM and TEM methods.
It was shown that the new-type of RS Al “flake” material is suitable not only for pigments but
also for powder metallurgical purposes, i.e. Al based nanocomposites.
By choosing suitable parameters for mechanical alloying with the Fritsch Planetary mill 4,
very fine, alloyed and composited nanostructures can be produced (Al-4.5w%Cu-
10w%Al2O3, Al-15w%Pb)
Dynamic compaction (HERF) using explosive techniques seems to offer a good way for the
compaction of Al (metal) matrix nanostructured composites.
321
Authors: D. Aranyi, Péter M. Nagy, Zs. Oláh, Erika Kálmán
Abstract: Radical reduction of sulphur content in diesel fuel from the mid 90’s had disastrous
impact on diesel fuel’s lubricity. Due to the desulphurization process the lubricity of diesel
fuel dropped significantly and got crucial nowadays. The lubricity performance of the diesel
fuel is evaluated by the HFRR test in Europe. The HFRR value is determined by measuring
the equivalent wear scar diameter occurred on the steel ball specimen during the test. The
topographies of these wear scars were investigated by AFM and correlation between the
morphology of the worn surfaces and the different HFRR values has been found.
285
Authors: Ioana Rotariu, Graziella L. Turdean, Fiammetta Kormos, Dan Macarovici, Gyula Tolnai, Ilona Felhősi, Péter M. Nagy, László Trif, Erika Kálmán
Abstract: The ZrO2 coatings were deposited by sol-gel techniques on copper and steel. The film
morphology has been investigated by AFM technique. The performance of ZrO2 films as protective
layers was investigated by electrochemical techniques and optical microscopy. Firstly, the
electrochemical behaviour of the uncoated copper and steel substrates was investigated by cyclic
voltammetry in HCl (1 M) and NaOH (0.4 M) solutions having various pH values. Secondly, the
anticorrosion protective effect of sol-gel ZrO2 coatings was evaluated by potentiodynamic
measurements in degrading media in which substrates were immersed for 1-90 days. The
comparisons of electrochemical parameters allow an explanation of the role of the ZrO2 coatings in
the increased resistance of steel and copper against corrosion in moderately aggressive
environments..
247
Authors: A. Paszternák, Ilona Felhősi, Z. Keresztes, Erika Kálmán
Abstract: Phosphonate layer formation on passive iron surface has been investigated by
electrochemical and atomic force microscopy techniques. It was found that phosphonate groups
bond more strongly to oxide surface, while metallic iron surface is disadvantageous for phosphonate
layer formation in aqueous solutions. The rate of anodic dissolution is continually decreasing due to
the time-dependent formation of protective phosphonate layer. The kinetics of phosphonate layer
formation on passive iron is determined by the potential applied for preceding passive film
formation. The size and shape of iron oxide grains depends slightly on the potential of passivation.
Changes in morphology due to the phosphonate layer formation have been recorded by AFM.
239