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  1. 60 Acta Physica Polonica A

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  1. 6 Gencer Y.

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  3. 4 Marcinauskas L.

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1
Content available remote

Effects of the Addition of Calcium Acetate into Silicate-Based Electrolytes on the Properties of MAO Coatings Produced on Zirconium

100%
Cengiz S., Azakli Y., Yazici M., Gayretli B., Gencer Y., Tarakci M.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
504-508
EN
Zirconium (Zr) is a potential implant material due to its excellent biocompatibility and low elastic modulus for biomedical applications. Its poor bioactivity, however, limits its use as biomaterials. In this study, microarc oxidation which is a plasma-electrochemical based process was applied to produce oxide coatings on pure zirconium. The coating processes were conducted in different electrolytes containing sodium silicate and varying amounts of calcium acetate tetrahydrate (CA) for 30 min to investigate the effect of the introduction of CA into the electrolyte solution on the morphology and chemical composition of the fabricated coatings. It was found that the coatings consisted of monoclinic-ZrO₂ and tetragonal-ZrO₂ phases. The amount of the tetragonal-ZrO₂ phase increased with the increasing CA concentration in the electrolyte. The coating thickness and surface roughness showed a tendency to increase with the increasing CA concentration in the electrolyte. It was observed that the vicinity of plasma channels were Zr-rich, while their surroundings were rich in Si and Ca elements. The outer region of the coating was denser compared to inner region consisting of Zr-rich porous structure.
2
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Atomic Layer Deposition of Magnetic Thin Films

100%
Mantovan R., Georgieva M., Perego M., Lu H., Cocco S., Zenkevich A., Scarel G., Fanciulli M.
Acta Physica Polonica A
|
2007
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vol. 112
|
issue 6
1271-1280
EN
We report on the research effort towards the development of processes for the realization of magnetic tunnel junctions by atomic layer deposition. Our strategy follows two main schemes. The first is a hybrid process where the ferromagnetic layers are produced by chemical vapour deposition and the tunnel oxide is deposited by atomic layer deposition. As ferromagnetic electrodes we use Co and Fe_3O_4, while MgO, Al_2O_3, and HfO_2 are employed as tunnel oxides. The second and most intriguing scheme is a full-oxide approach in which the ferromagnetic layers and the tunnel barrier layer are all oxides grown by atomic layer deposition. As ferromagnetic layers we focused on the growth of complex manganites (La_{0.7 Sr_{0.3 MnO_3) while as a tunnel oxide we propose La_2O_3. Film composition has been studied with time of flight secondary ion mass spectroscopy and Rutherford backscattering spectrometry. X-ray diffraction, X-ray reflectivity, and Fourier transform infrared spectroscopy have been used to investigate the structure and morphology of the layers. The magnetic properties of the films are measured by superconducting quantum interference device magnetometer.
3
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Oxide Based Ceramic Coating on Al-4Cu Alloy by Microarc Oxidation

100%
Cengiz S., Tarakci M., Gencer Y., Devecili A., Azakli Y.
Acta Physica Polonica A
|
2013
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vol. 123
|
issue 2
445-448
EN
In this study the Al-Cu aluminum alloy with 4 wt% Cu was prepared under controlled atmosphere and coated by microarc oxidation technique for the durations of 40, 80, and 120 min. The phase composition, surface roughness and hardness of the coating were characterized by X-ray diffraction, scanning electron microscopy, profilometry. The outer region contains larger sized porosities while fine porosities were formed in the inner dense region of the coating. The longer coating duration resulted in dense inner region with finely distributed α-Al_2O_3 precipitates. The presence of Cu in the outer region is not significant while the presence of Si in inner region was lower than in the outer region. Mullite and γ-Al_2O_3 phases were formed for 40 min and α-Al_2O_3 phase was additionally formed for 80 min and 120 min coating time. The coating thickness increased from 38 μm (40 min) to 115 μm (120 min) while the surface roughness (R_{a}) increased from 5 μm (40 min) to 9 μm (120 min).
4
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Plasma Electrolytic Oxidation of Binary Al-Sn Alloys

100%
Gencer Y., Tarakci M., Gulec A., Cagatay Oter Z.
Acta Physica Polonica A
|
2014
|
vol. 125
|
issue 2
659-663
EN
Binary Al-Sn (1, 2, 4, 6, 8 at.% Sn) synthetic alloys were prepared under vacuum-atmosphere controlled furnace. The Al-Sn alloys were coated by plasma electrolytic oxidation technique for 120 min in aqueous electrolyte containing sodium silicate and potassium hydroxide using the same electrical parameters. The microstructure, surface roughness, phase content and chemical composition of the coatings were characterized by scanning electron microscopy, profilometry and X-ray diffractometry. The coating became porous while coating thickness and surface roughness decreased, with increasing amount of Sn content in Al-Sn alloys. The coating was not formed on the Al-Sn alloy with 8 at.% Sn. Plasma electrolytic oxidation coatings were composed of mainly mullite (3Al_2O_3 ·2SiO_2), γ-Al_2O_3 and α-Al_2O_3 up to 4 at.% Sn. The α-Al_2O_3 phase formed as precipitate in the inner region of the coating and its amount decreased with Sn amount in the Al-Sn alloys. The SnO_2 phase was only detected in the coating of Al-6Sn alloy. Scanning electron microscopy - energy dispersive X-ray spectroscopy results showed that the traces of Sn were evident in the oxide coating along with Al, O, Si, Na, and K. The increasing addition of Sn in the alloys resulted in reduction of the overall microhardness of the coating with decreasing manner from dense inner region to the surface of the coatings.
5
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Micro Arc Oxidation of Al-4Si, Al-4Mn and Al-4Mg Binary Alloys

100%
Oter Z., Gulec A., Gencer Y., Tarakci M.
Acta Physica Polonica A
|
2015
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vol. 127
|
issue 4
1331-1335
EN
Binary synthetic aluminum alloys Al-M (M = Mg, Mn, Si) containing 4 at.% alloying elements as substrate materials were prepared under controlled vacuum/argon atmosphere. The substrates were coated by micro arc oxidation (MAO) method for 120 minutes in aqueous alkaline electrolyte using the same electrical parameters. The phase constituents, chemical composition, surface roughness and the microstructure of the coatings were characterized by XRD, profilometry and SEM-EDS. The average coating thicknesses are 127 μm, 91 μm and 78 μm on Al-4Mn, Al-4Mg and Al-4Si alloys, respectively. All MAO coatings were composed of mullite (3Al₂O₃·2SiO₂) and γ-Al₂O₃ phases. In addition to these phases, α-Al₂O₃ phase, in the form of precipitates, was detected in coatings on Al-4Mn and Al-4Mg alloys. The presence of Si, Mn and Mg was detected in the coatings, depending of the chemical content of the substrate alloys.
6
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Characterization of Coating Formed on Pure Zirconium by MAO in Yttrium Acetate Tetrahydrate Containing Electrolyte

100%
Cengiz S., Yazici M., Gencer Y., Tarakci M.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 4
1320-1325
EN
In this study, oxide coatings were produced on pure zirconium by micro arc oxidation method in the electrolytes containing sodium silicate and different amounts of yttrium acetate tetrahydrate (1-4 g/l) for the same coating duration of 1 h. The surface roughness, microstructure, phase content and chemical composition of the coatings were characterized by using scanning electron microscopy, profilometry and X-Ray diffractometry. It was found that the surfaces of coatings on zirconium consist of monoclinic-ZrO₂, tetragonal-ZrO₂ phases. The coating thickness decreases with addition of yttrium acetate tetrahydrate while it does not change significantly with the increase of its amount. The clustered equiaxed features were formed on the surfaces of the coatings. As the amount of yttrium acetate tetrahydrate in the electrolyte solution increased, the coating/substrate interface smoothened. Two main regions of the coating, the outer dense region (I) and the porous inner region (II), became significant with addition of YAT into the electrolyte.
7
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Properties of Ultra Fast Deposited Diamond-Like Hydrogenated Carbon Films

100%
Sullivan J., Saied S., Zaharia T.
Acta Physica Polonica A
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2011
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vol. 120
|
issue 1
156-162
EN
Hydrogenated amorphous carbon films with diamond like structures have been formed on different substrates at very low energies and temperatures by a plasma enhanced chemical vapor deposition process employing acetylene as the precursor gas. The plasma source was of a cascaded arc type with Ar as carrier gas. The films were grown at very high deposition rates. Deposition on Si, glass and plastic substrates has been studied and the films characterized in terms of sp^3 content, roughness, hardness, adhesion and optical properties. Deposition rates up to 20 nm/s have been achieved at substrate temperatures below 100°C. The typical sp^3 content of 60-75% in the films was determined by X-ray generated Auger electron spectroscopy. Hardness, reduced modulus and adhesion were measured using a MicroMaterials Nano Test Indenter/Scratch tester. Hardness was found to vary from 4 to 13 GPa depending on deposition conditions. Adhesion was significantly influenced by the substrate temperature and in situ DC cleaning. Hydrogen content in the film was measured by a combination of the Fourier transform infrared and Rutherford backscattering techniques. Advantages of these films are: low ion energy and deposition temperature, very high deposition rates, low capital cost of the equipment and the possibility of film properties being tailored according to the desired application.
8
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Nanostructured Thin Films β-Al-Mg Obtained Using PLD Technique

80%
Radziszewska A., Kąc S., Feuerbacher M.
Acta Physica Polonica A
|
2010
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vol. 117
|
issue 5
799-802
EN
In this work, the pulsed laser deposition (PLD) technique was used to grow AlMg thin films from a β-Mg_{2}Al_{3} target with nominal composition: 39.09 at.% Mg and 60.91 at.% Al. The paper presents the study of β-Mg_{2}Al_{3} thin films deposited using the pulsed laser deposition technique. AlMg thin films were prepared on Si (400) substrates and deposited by means of using a QS-Nd:YAG laser (λ = 266, 355 nm). Samples were prepared with laser fluence (1.1 J/cm^{2} and 1.6 J/cm^{2}) and at two different substrate (Si) temperatures (25°C and 200°C). The target possessed columnar structure and changes in chemical composition took place as a result of the influence of the laser irradiation. Investigations focused on structure and chemical composition showed that the films generally had nanocrystalline structure and that the quantity of Al and Mg varied in the films.
9
Content available remote

Garnet Single Crystal as Substrate Material for HTSC Films

80%
Mukhopadhyay P.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 1
147-151
EN
The use of high temperature superconductor for device application has made the compatibility of the film and substrate an important issue. Garnets having reasonably low dielectric constant and low dielectric losses can be viable low cost substrate materials for the microwave devices. Garnet single crystals like Gd_{3}Ga_{5}O_{12} (GGG), Y_{3}Ga_{5}O_{12} (YGG), Y_{3}Al_{5}O_{12} (YAG) etc. can be potential HTSC substrate materials for microwave devices. Properties of HTSC films on some of these garnet crystals are compared here.
10
Content available remote

Growth of Laser Ablated YBa_{2}Cu_{3}O_{7} Thin Films Epitaxied on (100)MgO: Influence of In-Plane Misorientations on Low and High Frequency Properties

80%
Perrin A., Guilloux-Viry M., Castel X.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 1
115-125
EN
The graphoepitaxial growth of c-axis YBa_{2}Cu_{3}O_{7} laser ablated thin films on (100)MgO induces a competition between two main in-plane orientations due to the large lattice mismatch: ⟨100⟩ YBa_{2}Cu_{3}O_{7} ∥ ⟨100⟩ MgO, c_{⊥ 0} notation or ⟨110⟩ YBa_{2}Cu_{3}O_{7} ∥ ⟨100⟩ MgO, c_{⊥ 45} notation. The ratio of c_{⊥ 45}/c_{⊥ 0} in-plane orientations (η), measured by X-ray diffraction φ scans, is ranging from 0.2% to 49.7% for the films reported here. Their crystalline qualities were compared on the basis of rocking curves (Δθ), electron channeling patterns and reflection high energy electron diffraction diagrams. The coexistence of c_{⊥ 0} and c_{⊥ 45} domains creates high angle grain boundaries. No degradation of T_{c}, residual resistance ratio (RRR) or ΔT_{c} is observed when η increases. In contrast, a strong correlation between microwave losses characterized by surface resistance (R_{S} at 10 GHz and 77 K), inductive losses S(χ") (surface of the χ" peak obtained in a.c. susceptibility at 119 Hz) and η was clearly evidenced. A minimum of losses was found for η between 3 and 6% suggesting the necessity of a low quantity of high angle grain boundaries for films optimization. Finally, some specific processes carried out recently in order to try to efficiently control η, then R_{S} are discussed.
11
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Preparation and Characterization of Copper Powders with Sn Coating by the Electroless Plating

80%
Uysal M., Cetinkaya T., Gul H., Kartal M., Algul H., Tokur M., Alp A., Akbulut H.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 4
1106-1108
EN
In this work, Sn-Cu composite powders were produced using an electroless process. The tin content on the surface of copper powders was varied by using different concentrations of SnSO₄ in the plating bath. The surface morphology of the produced Sn-Cu composite powders was characterized using scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) was used to determine the elemental surface composition of the composites. X-ray diffraction (XRD) analysis was performed to investigate the structure of the Sn-Cu composite powders. The electrochemical performance of Sn-Cu nanocomposites was studied by charge/discharge tests.
12
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Structural Characterization of Al_2O_3 and CeO_2 Supported Ni, Co Loaded Ceramic Monolithic Catalysts

80%
Guldal N., Baykara S.
Acta Physica Polonica A
|
2014
|
vol. 125
|
issue 2
281-284
EN
This paper discusses structural characterizations of monolithic catalysts prepared by incorporating Ni and Co supported over a porous alumina and ceria layer by using respective nitrates and H_2PtCl_6 as precursors. Monolithic catalysts were synthesized by dip-coating of 400 cpsi cordierite ceramic monolithic pieces cut in 20 × 13 mm^2 (L× D) into appropriate solutions of metals, followed by calcination in air at 800C for 4 h. Phases of catalysts were characterized with X-ray diffraction. Morphological analysis and elemental composition were determined by scanning electron microscope and energy dispersive spectroscopy. The specific surface area analysis have been studied using the Brunauer-Emmett-Teller method. Metal contents were determined by inductively coupled plasma optical emission spectrometry.
13
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Enhanced Capacitance of Porous Carbon Electrodes through Deposition of Small Amounts of NiO

80%
Kavaliauskas Z., Marcinauskas L., Valatkevicius P.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 1
66-69
EN
Amorphous carbon and NiO/carbon composites were used as an electrode material for supercapacitors. The investigations were performed to evaluate the influence of the Ar/C_2H_2 ratio on the capacitance values of carbon and NiO/carbon electrodes. The surface morphology of the carbon electrodes changes from snowflake-like to columnar with the increase of the Ar/C_2H_2 ratio. The Raman scattering spectroscopy results demonstrated that the I_{D}/I_{G} ratio decreases from 1.33 to 0.91 with the increase of the Ar/C_2H_2 ratio. It indicates the decrease of the sp^2 bonded carbon in the coatings. The specific capacitance of the carbon electrodes increases with the increase of the Ar/C_2H_2 ratio. The NiO/carbon electrodes show capacitance values 10 times larger as those of carbon electrodes. The largest specific capacitance of 27.7 F/g was obtained for NiO/carbon electrode, when carbon coating was deposited under Ar/C_2H_2=27.
14
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Study of Structure Densification in TiO_2 Coatings Prepared by Magnetron Sputtering under Low Pressure of Oxygen Plasma Discharge

80%
Domaradzki J., Kaczmarek D., Prociow E., Radzimski Z.
Acta Physica Polonica A
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2011
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vol. 120
|
issue 1
49-52
EN
Current work presents results of studies on structural and optical properties of the TiO_2 thin films prepared by reactive magnetron sputtering. Oxide thin films were deposited from metallic targets using oxygen gas only instead of usually used mixture of Ar-O_2. Additionally, an increased amplitude of unipolar pulses powering the magnetron has been applied. It is shown that all prepared coatings were stoichiometric and by changing only the discharge voltage it is possible to influence the resulting structural phase and optical properties of prepared thin films. Depending on conditions of magnetron powering, TiO_2 thin films had either the anatase structure with refraction index n = 2.1 (λ = 500 nm) or a high temperature stable rutile structure with n = 2.52 (λ = 500 nm).
15
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Deposition of Amorphous Hydrogenated Carbon Coatings by Plasma Jet

80%
Marcinauskas L., Grigonis A., Manikowski H., Valincius V.
Acta Physica Polonica A
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2008
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vol. 113
|
issue 3
1063-1066
EN
In this study amorphous hydrogenated carbon films (a-C:H) were formed on Si (111) from an Ar-C_2H_2 and Ar-C_2H_2-H_2 gas mixtures at 1000 Pa pressure using a plasma jet chemical vapour deposition. It is shown that by varying the Ar:C_2H_2 ratio and adding the hydrogen gas in plasma, the structure, surface morphology, growth rate of the coatings, and consequently their optical properties can be controlled.
16
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Self-Ion Assisted Modification of Elastomer and Its Micro- and Macroscopic Properties

80%
Kasperovich A., Luhin V., Tashlykov I., Żukowski P.
Acta Physica Polonica A
|
2014
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vol. 125
|
issue 6
1421-1424
EN
The composition of Zr-based thin films on rubber was investigated by utilizing the Rutherford backscattering technique and RUMP code simulation. The level of adhesion between the coating fabricated on rubber by means of self-ion assisted deposition was measured using Pin Pull Test. The coating deposited on the rubber consists of Zr, O, C, H. The self-ion assisted deposition process may successfully control the level of adhesion of the coating to the rubber and causes strong modification of the macroscopic properties of the rubber surface.
17
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Determination of the Direction of the c-Axis of L1_0 FePt Thin Films with the MÖssbauer Spectroscopy

80%
Laenens B., Almeida F., Vantomme A., Meersschaut J.
Acta Physica Polonica A
|
2007
|
vol. 112
|
issue 6
1313-1318
EN
The continued growth of storage capacity requires new innovations in recording media and in particular, in magnetic nanostructures. FePt thin films in the L1_0-phase are interesting candidates for high-density magnetic recording media due to their large magnetocrystalline anisotropy. In the present work, we investigated the magnetic and structural properties of FePt thin films directly grown on MgO(110) with molecular beam epitaxy. The purpose was to gain insight in the correlation between the magnetization process and the morphology of the FePt thin films. We introduce conversion electron MÖssbauer spectroscopy to derive the direction of the easy magnetization axis with respect to the substrate. The results are compared to the characterization performed with high angle X-ray diffraction.
18
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Formation and Characterization of Carbon and Nickel Oxide/Carbon Composites for Supercapacitors

80%
Kavaliauskas Z., Marcinauskas L., Valatkevicius P.
Acta Physica Polonica A
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2011
|
vol. 119
|
issue 2
253-255
EN
In this study a carbon and NiO/carbon electrodes were prepared and investigated. The surface roughness increases with the increase of the torch power. The addition of the NiO changes the surface structure from a snowflake-like to a mesh-like. It was demonstrated that the addition of the nickel oxide to amorphous carbon increases the specific capacitance of composite electrode. However, the NiO/carbon electrodes have a lower breakdown voltage values and longer charge-discharge cycles.
19
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The Study of Electroless Ni-P/Ni-B Duplex Coating on HVOF-Sprayed Martensitic Stainless Steel Coating

80%
Mindivan F., Mindivan H.
Acta Physica Polonica A
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2017
|
vol. 131
|
issue 1
64-67
EN
High velocity oxygen fuel sprayed stainless steel coatings have been widely used in various industries to repair damaged components. However, its broad application is limited due to its comparatively low hardness and inferior tribological properties. In this work, electroless Ni-P/Ni-B duplex coating with a thickness of ≈ 40 μm was deposited on surfaces of HVOF-sprayed 420 martensitic stainless steel substrate, and its structural, corrosion and tribological properties were characterized. Experimental results showed that upper Ni-B coating deposited on the surface of first Ni-P layer by duplex treatment exhibited superior hardness, wear and corrosion resistances as compared to the HVOF-sprayed 420 martensitic stainless steel coating with a thickness of about 150 μm.
20
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The Comparative Study of the Structure and Phase Composition of Ni-Based Coatings Modified by Plasma Jet or Electron Beam

80%
Alontseva D., Russakova A., Krasavin A.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
838-841
EN
The paper deals with the results of the comparative study into the structure and phase composition, as well as some properties (microhardness, corrosion resistance) of Ni-based powder coatings before and after their modification by DC electron beam or DC pulse plasma jet, according to the modes recommended on the basis of model calculations of the temperature profiles at irradiation. The transmission electron microscopy and X-ray analysis have revealed that irradiation leads to an increase in the volume fraction of reinforcing nanosized intermetallic components in the coatings. There were established certain similarities and differences in the structure and properties of the coatings modified by different types of irradiation. The microhardness of the irradiated coatings has increased in both cases along with the growth of the volume fraction of the CrNi₃ particle phase. However, it was found that the diffusion zone in the coatings modified by plasma jet is higher than that of the coatings modified by electron irradiation. The coating surface melted by the electron beam has a marked reduction of its roughness and better homogenization of the microstructure therefore demonstrating better adhesion and corrosion resistance.
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