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1
Content available remote

Enhanced Corrosion Resistance of Silicone-Coated Stents by Plasma Treatment

100%
Kim H., Baik K., Moon M., Sung C.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
857-860
EN
The interfacial bonding of silicone-coated stents was characterized by field emission scanning electron microscopy and anodic potentiodynamic polarization tests. The coaxial in-lens secondary electron imaging revealed partial bonding between silicon rubber and nitinol alloy strips in both primer-treatment and plasma-treatment cases. Several strands between the polymer and stent substrate were observed in both cases and it seems that the bonding strength is the same. However, potentiodynamic polarization tests have shown that the corrosion rates of the plasma-treated nitinol stents were less than half of that of the primer-treated stents, indicating higher corrosion resistance. This enhanced corrosion resistance may be attributed to the modification of the physical properties of the surface of the stents by plasma treatments, making the oxide layer more effective than that of the primer-treated stents.
2
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The Effect of Process Parameters on Surface Behaviors of Low Carbon Steels Modified by Pulse Plasma Technique

100%
Agdaş G., Özbek Y.
Acta Physica Polonica A
|
2014
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vol. 125
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issue 2
393-395
EN
In this study, microstructure and surface properties of low carbon steels (St52) treated by pulse plasma were investigated. The surfaces of samples were modified by pulse plasma technique. Four different plasma gun nozzle distances as 50 mm, 60 mm, 70 mm, and 80 mm and one battery capacity were chosen for surface modification. Cross-section microstructures of samples were investigated and modified layer thicknesses were measured by optical microscope. The thickness values of modified layer were obtained in a range from 10 μm to 41 μm. The samples were immersed into liquid nitrogen and then breaked in a Charpy machine. The fractured surfaces were exposed to scanning electron microscopy analyses. At the end of the study, thin grains and small tungsten grains coming from tungsten electrode were detected. After pulse plasma treatment, new structures and new phases and high hardness values were obtained.
3
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Surface Carburizing by Valorization of Organic Waste

63%
Boutessouna B., Allaoui O., Allaoui L.
Acta Physica Polonica A
|
2017
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vol. 132
|
issue 3
1173-1175
EN
The organic waste recycling problem remains an important economic issue for the industry, where much research is done in this area. In this study, we are interested in the enhancement of some organic waste from slaughterhouses (blood and horns) with two objectives: recycling wastes and producing cheap cement for surface carburizing. The waste is converted into coal and added to an activator to produce a solid medium, witch can be used for surface carburizing of carbon steels. Preparation of waste and physical and chemical carbonating of blood and horns resulted in production of coal, that was used as an effective carbon source for cementation treatment. Comparison of the obtained results with other works on carburizing treatment, using industrial solid mixtures, has shown that carburizing layers in both cases are very similar. Indeed, metallographic analysis, X-ray diffraction and Vickers hardness testing of obtained layers have led to results very similar to those in literature.
4
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Pack Siliconizing of Ti6Al4V Alloy

63%
Celebi Efe G., İpek M., Bindal C., Zeytin S.
Acta Physica Polonica A
|
2017
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vol. 132
|
issue 3
760-762
EN
In this study, it was aimed to produce titanium silicide layer on Ti6Al4V by a simple, cheap and efficient method of pack siliconizing. Siliconizing was performed in a pack containing a mixture composed of SiO₂ powder as siliconizing source, pure Al powder as a reducer for siliconizing, NH₄Cl as an activator and Al₂O₃ powder as filler, at 1000°C for 8, 10 and 12 hours in open atmospheric furnace. Optical microscope and SEM-EDS studies indicate that the morphology of silicide layers has smooth, dense and layered nature. The presence of phases, confirmed by XRD analyses, reveals that the silicide layers formed at 1000°C are composed of TiSi₂, Ti₃Si₅, TiN, TiO₂ and SiO₂ compounds. Silicide layer thickness was increased with increasing process time and ranged from 7.5 to 9.0 μm. Hardness of silicide layers, measured by Vickers indentation, is over 2100 HV.
5
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The Effect of Low Temperature Plasma Nitriding on Wear Resistance of Ti6Al4V Alloy

63%
Gul O., Sari N., Sinmazcelik T.
Acta Physica Polonica A
|
2014
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vol. 125
|
issue 2
491-493
EN
The effect of low temperature plasma nitriding on wear resistance of Ti6Al4V alloy were investigated. There have been several studies to investigate the low temperature plasma nitriding on Ti6Al4V alloy. Plasma nitriding processes under gas mixture of N_2/H_2 = 3 were performed at temperature 535C for duration of 4, 8 and 12 h. Adhesive wear tests were carried out by using a tribometer in block-on-ring configuration (ASTM G77), in sliding conditions, without lubricants and in air. Surface hardness of the plasma nitrided samples were measured by a Vickers hardness tester machine. Scanning electron microscopy studies were conducted to understand the wear mechanisms involved during the adhesive wear. Wear rate was calculated using weight loss per unit sliding distance. It was found that the wear resistance and surface hardness of the alloy improved considerably after plasma nitriding process. The wear resistance of the plasma nitrided samples were higher than of the unnitrided samples. Extension of nitriding times from 4 h to 12 h in the Ti6Al4V alloy improved remerkably the wear resistance and surface hardness.
6
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An Investigation on Surface and Electrical Properties of Electrical Discharge Machined AISI D2 Tool Steel

63%
Durmus A., Bayram A., Gunes S., Akay S.
Acta Physica Polonica A
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2014
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vol. 125
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issue 2
515-517
EN
The effects of pulse-on duration and finishing operation on the surface roughness and electrical resistivity of AISI D2 tool steel machined by the electrical discharge machining process are investigated. Experimental results indicate that surface roughness increased depending on the pulse-on duration. However, after the specific value, surface roughness is decreased. It can be seen that there are no notable effects of the pulse-on duration on the electrical resistivity, but the resistivity values are affected by the heat treatment and the finishing operation. Also, light microscopy and scanning electron microscopy have been used to study the characteristics of the surfaces.
7
Content available remote

Improved Nucleation and Transition by Plasma Treatments for Fast Response Optically-Compensated-Bend Displays

51%
Wu G., Huang C., Chien H.
Acta Physica Polonica A
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2013
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vol. 123
|
issue 5
892-895
EN
The optically-compensated-bend mode pi-cell displays exhibit fast-response time and wide-viewing angle characteristics. However, it requires a transition of the liquid crystal molecule from an initial splay state to the bend state configuration before providing the quick operation. A high voltage and a long warm-up time are needed to transform to the bend state. In this paper, the polyimide alignment films have been modified to reduce the splay-to-bend transition time by plasma beam treatments. The proposed method was demonstrated to be highly effective in improving the overall transition time. The number of splay-to-bend nucleation sites in the assembled liquid crystal cells could be increased dramatically by up to 20 times at the initial stage, and the improvement in the cell warm-up time was achieved at 45-71% reduction at 5.5 V. The plasma processing parameters were optimized at the plasma power of 700 W, the plasma distance of 25 mm, and the plasma scan speed of 600 mm/s. In addition, we maintained the excellent optical properties and response time characteristics for the optically-compensated-bend mode liquid crystal displays.
8
Content available remote

Ion Beam Surface Modification of GaN Films for High Efficient Light Emitting Diodes

51%
Wu G., Lin Y., Tu K.
Acta Physica Polonica A
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2013
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vol. 123
|
issue 5
884-887
EN
Focused gallium (Ga) ion beam technology has been proposed to modify the surface of GaN thin films. Due to the significant advancement in nitride semiconductors, the solid-state light emitting diodes will gradually replace fluorescent lamps in the next decade. However, further improvements in light extraction and power efficiency are still highly desired. GaN is limited by its high refractive index, with low light escape cone angle at about 24.6°. The external quantum efficiency is low due to the unwanted reflection and absorption. As the patterning technology scales down to the nanometer level, photonic crystal lattice in the visible light wavelength range can be achieved. Therefore, we improved the external efficiency by the new design of hexagonal photonic crystal lattice with air hole arrays in the diameter of 150 nm and the depth of 120 nm. The Ga beam was accelerated at 30 kV and the ion current was 100 pA. The plane wave expansion method along with the finite difference time domain was useful to investigate the quantum confinement. The nanopatterning by the focused ion beam could save time and processing step. In addition, we have successfully prepared blue InGaN/GaN samples with hexagonal period of 200 nm. The device micro-photoluminescence results have demonstrated that the peak illumination intensity was improved by 30%.
9
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The Effect of Ammoxidation Process on NO_2 Sorption Abilities of Active Carbons

51%
Nowicki P., Pietrzak R., Dobkiewicz M., Wachowska H.
Acta Physica Polonica A
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2010
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vol. 118
|
issue 3
493-499
EN
The paper presents results of a study on obtaining N-enriched active carbons from Polish brown coal and on their use as adsorbents for removal of pollution from gas phase. The crushed precursor was subjected to carbonisation at 500, 600 and 700°C in argon atmosphere. The chars obtained were activated by KOH at 800°C. The active carbons were further subjected to the ammoxidation at 350°C for 3 h, by a mixture of ammonia and air at the ratio of 1:3. The final products were microporous active carbons of well-developed surface area reaching to 2849 m^2/g and pore volume to 1.49 cm^3/g, showing mixed acid-base character of the surface. The results have shown that a suitable choice of the carbonisation, activation and ammoxidation procedures for brown coal can lead to obtaining activated carbons with high nitrogen dioxide adsorption ability, reaching from 16.9 to 36.4 mg NO_2/g.
10
Content available remote

Polycarbonate Polymer Surface Modification by Extreme Ultraviolet (EUV) Radiation

51%
Ahad I., Budner B., Korczyc B., Fiedorowicz H., Bartnik A., Kostecki J., Burdyńska S., Brabazon D.
Acta Physica Polonica A
|
2014
|
vol. 125
|
issue 4
924-928
EN
The degree of the biocompatibility of polycarbonate (PC) polymer used as biomaterial can be controlled by surface modification for various biomedical engineering applications. In the past, PC samples were treated by excimer laser for surface reorganization however associated process alteration of bulk properties is reported. Extreme ultraviolet radiation can be employed in order to avoid bulk material alteration due to its limited penetration. In this study, a 10 Hz laser-plasma EUV source based on a double-stream gas-puff target irradiated with a 3 ns and 0.8 J Nd:YAG laser pulse was used to irradiate PC samples. The PC samples were irradiated with different number of EUV shots. Pristine and EUV treated samples were investigated by scanning electron microscopy and atomic force microscopy for detailed morphological characterization of micropatterns introduced by the EUV irradiation. Associated chemical modifications were investigated by X-ray photoelectron spectroscopy. Pronounced wall-type micro- and nanostructures appeared on the EUV modified surface resulting in a change of surface roughness and wettability.
11
Content available remote

Evaluation of Properties of the Laser Modified Surface Layer

51%
Bień A., Szachnowski W.
Acta Physica Polonica A
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1999
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vol. 96
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issue 2
263-273
EN
This research concerns a surface layer formed on 21H12NMFA steel with a continuous wave 6 kW CO_{2} laser. The purpose of the study was the determination of the physical properties of the layer with chosen methods of identification. Electromagnetic method with a point probe has been used to determine the homogeneity in numerous points of the layer. Optic and electron (TEM) microscopy enabled the identification of the microstructure of the layer, whereas using Hanemann's meter the microhardness on the surface of the sample, and also its distribution in the layer, could be evaluated. The complex characteristic of the laser formed surface layer based on the results of the above methods of investigation is presented. The study has shown that the electromagnetically determined homogeneity of the surface layer (i.e. concerning its permeability and permittivity) can be also related to thickness, structure, and microhardness of the layer.
12
Content available remote

Carbon Monolith Surface Chemistry Influence on the Silver Deposit Amount and Crystallite Size

51%
Vukčević M., Kalijadis A., Jovanović Z., Laušević Z., Laušević M.
Acta Physica Polonica A
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2011
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vol. 120
|
issue 2
284-288
EN
The surface of carbon monolith (CM) was chemically treated in order to obtain antibacterial filters with silver deposit for water treatment. The chemical treatment involved submerging the as-received CM in HNO_{3}, KOH and H_{2}O_{2} solution. The specific surface area was examined by N_{2} adsorption. Silver deposition at the surface of CM samples was performed using cheap and simple procedure of immersing CM samples in aqueous solution of AgNO_{3}. Temperature programmed desorption method has been used in order to investigate the nature and thermal stability of surface oxygen groups before and after silver deposition. The composition and crystalinity of silver deposits have been examined by X-ray diffraction. Chemical treatment does not cause any drastic changes of CM specific surface area, but increases a total amount of surface oxides. Amount of deposited silver is several times higher for all chemically treated samples. The results show that increasing the amount of CO yielding groups on CM surface leads to increased amount of Ag deposit and decreases its crystallite sizes
13
Content available remote

Extreme Ultraviolet Surface Modification of Polyethylene Terephthalate (PET) for Surface Structuring and Wettability Control

51%
Ahad I., Fiedorowicz H., Budner B., Kaldonski T., Vázquez M., Bartnik A., Brabazon D.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 2
241-243
EN
The surface modification of polyethylene terephthalate (PET) polymer films has been performed by irradiation of extreme ultraviolet photons to investigate the effect of surface structuring on wettability control. For biomedical engineering applications, surface structuring and wettability control of PET films could enhance the polymer biocompatibility by promoting cell adhesion and consequently proliferation. The PET films are irradiated with laser plasma extreme ultraviolet source based on double stream gas puff target under different environments. The extreme ultraviolet modified PET film surfaces are characterized by atomic force microscopy and WCA goniometer. The extreme ultraviolet surface modification resulted in the formation of nano- and microstructuring on the polymer surfaces. The surface structuring consequently increased WCA making the PET surfaces more hydrophobic. The results demonstrate the direct relationship between surface roughness and hydrophobicity for extreme ultraviolet modified PET samples.
14
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Growth Characteristics of Plasma Electrolytic Oxidation Coatings on Aluminum Alloys

51%
Ayday A., Durman M.
Acta Physica Polonica A
|
2015
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vol. 127
|
issue 4
886-887
EN
The ceramic coating on aluminum alloy was prepared in sodium metasilicate electrolyte by plasma electrolytic oxidation (PEO). The effect of PEO treating time on surface layer was investigated. The morphology and phase composition of the ceramic coatings were characterized by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The effect of the electrolyte contents on the growth mechanism, element distribution and properties of oxide layers were studied. Oxide coatings morphology is strongly dependent on PEO process time. The microdischarges characteristics were studied as well, and it is shown that size of microdischarges becomes larger with increasing time of PEO. XRD analysis showed that Plasma Electrolytic Oxidation coating has hard, dominantly Al₂O₃ phase.
15
Content available remote

Optimization of Surface Properties of Shot Peened TI6AL4V Alloy

51%
Yıldıran Y., Avcu E., Sınmazçelik T.
Acta Physica Polonica A
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2015
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vol. 127
|
issue 4
984-986
EN
As an important surface treatment method, shot peening (SP) is widely used in automotive and aerospace industries in order to improve surface properties. In the present study SP was performed on the α-β titanium alloy Ti6Al4V under various parameters (particle impingement angle, particle acceleration pressure and particle size) by using a specially designed shot peening test rig. It is aimed to optimize surface roughness and hardness of the shot peened Ti6Al4V alloy under various parameters. In order to achieve this goal shot peened samples were investigated in detail by using a non-contact laser optical profilometer and surface hardness of the samples was measured by using a micro-hardness instrument. The surface roughness values, 3D surface morphologies and micro-hardness of the samples were obtained and examined. The results show that particle impingement angle, particle acceleration pressure and particle size dramatically affect the surface properties of the Ti6Al4V alloy.
16
Content available remote

Reciprocating Wear Behavior of Ductile Cast Iron Modified by Pulse Plasma Technology

51%
Ayday A., Durman M.
Acta Physica Polonica A
|
2014
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vol. 125
|
issue 2
189-191
EN
Wear resistance of ductile iron can be improved through different surface engineering techniques, each having some limitations and drawbacks. Recently, a new method called pulse plasma technology has been introduced, which through local reinforcement with inserts improves wear resistance of ductile iron without compromising other properties. This paper deals with the improvement of the wear resistance of ductile iron surface modified by pulse plasma technology using a tungsten electrode. The surfaces of the samples were treated by C_3H_8, air, and oxygen gases. The surface morphology and the phase structure in the near surface region of original and treated samples were analyzed with optic microscope, scanning electron microscope and energy-dispersive spectroscopy. The surface properties were evaluated by measuring the microhardness, wear properties and friction coefficient, as well as the elemental depth profiles and chemical composition of the modified layer. It was found that the microhardness of the treated samples was much higher. The tribological resistances were also significantly improved, as confirmed by the reduced friction coefficient and wear track width. This improvement can be attributed to the diffusion of tungsten on the surface layer.
17
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Enrichment of AISI 316L Steel Surface Layer with Rare Earth Elements Using Ion Beams

51%
Sartowska B., Waliś L., Starosta W., Barlak M., Pochrybniak C., Kowalska E.
Acta Physica Polonica A
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2013
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vol. 123
|
issue 5
822-824
EN
Enrichment of AISI 316L steel surface layers with rare earth elements was carried out using two methods with ion beam applying. The first one was the ion implantation with the doses in the range of 1 × 10^{15} cm^{-2} up to 5 × 10^{17} cm^{-2} where mishmetal (Ce+La) was used as the ion source. The second method was the high intensity pulsed plasma beams. The plasma pulses contained both ions/atoms of Ce+La from the electrodes material (mishmetal). The pulse energy densities (3 J/cm^2) were sufficient to melt the near surface layer of the steel and introduce those elements into the surface layer. The aim of this work was to investigate the changes of stainless steel surface properties (morphology, rare earth elements concentration, presence of identified phases) after the rare earth elements addition with or without melting. Scanning electron microscopy, energy dispersion spectroscopy, and X-ray diffraction analysis were used for initial and modified surface characterisation. Grazing-incidence X-ray diffraction shows differences in the identified phase presence in the modified surface layer connected with the modification method.
18
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Treatment Techniques on Aluminum to Modify the Surface Wetting Properties

51%
Torrisi L., Scolaro C.
Acta Physica Polonica A
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2015
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vol. 128
|
issue 1
48-53
EN
Different techniques of surface treatment are employed to modify the physical properties of aluminum surfaces. Experimental data report measurements of water wetting ability in aluminum surfaces treated with six different techniques: polishing, sanding, acid attach, laser ablation, ion implantation and nanoparticle deposition. Surfaces can be modified as a function of the different treatment parameters. Treatment duration, roughness and morphology play an important role in determining the properties from hydrophobic to hydrophilic behavior.
19
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Modification of Polymer Substrates with Extreme Ultraviolet - Potential Application in Cancer Cell Identification

51%
Ahad I., Pabijan J., Pogoda K., Hughes C., Bartnik A., Fiedorowicz H., Lekka M., Brabazon D.
Acta Physica Polonica A
|
2018
|
vol. 133
|
issue 2
283-285
EN
During the last two decades, the development of laboratory scale extreme ultraviolet sources has been intensified due to growing interest in use of extreme ultraviolet photons for various applications in science and technology. In this study, we present a potential application of extreme ultraviolet sources for surface modification of polymers to be used as substrates for cancer cell identification. The surface modification of polytetrafluoroethylene (PTFE) polymer samples was performed by a lab scale compact laser-plasma extreme ultraviolet source based on a double-stream gas-puff target. The gas target was irradiated with a 3 ns/0.8 J Nd:YAG laser pulse at 10 Hz. Reference HCV29 non-malignant transitional epithelium and T24 bladder cancer cells adhesion and proliferation studies on pure and extreme ultraviolet sources modified PTFE surfaces were performed. The extreme ultraviolet modified surfaces demonstrated regular increase in cancer cell proliferation comparing to pristine sample. Initial results indicate that extreme ultraviolet treated substrates can facilitate the identification of cancer cells.
20
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Wear Behavior of Surface Treated X45MoCrV5-3-1 Tool Steel at Room and Elevated Temperatures

51%
Aktaş G., Polat Ş., Atapek Ş.
Acta Physica Polonica A
|
2015
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vol. 127
|
issue 4
1221-1224
EN
The aim of this study is to compare the wear behavior of X45MoCrV5-3-1 tool steel, used as die material in aluminum extrusion, after single treatment (CrN coating) and duplex treatment (nitriding and CrN coating). Gas nitriding and physical vapor deposition were used as processing techniques and wear tests were carried out at both room and elevated temperatures. A "ball-on-disc" type tribometer was used for room temperature tests, utilizing Al₂O₃ ball as counterpart. In order to simulate the wear conditions during extrusion, hot wear tests were carried out at 450°C using "block-on-cylinder" type tribometer against AA 6080 material. Worn surfaces were studied by microscopy to reveal the wear characteristics of treated steels. It was found that (i) duplex treated steel, having higher friction coefficient at room and elevated temperature, had higher wear resistance, (ii) at room temperature single treated steel exhibited higher volume loss than the duplex treated one, (iii) at elevated temperature duplex treated steel revealed a stable coating layer, whereas micro cracks were observed on the surface of the single treated steel.
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