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1
Content available remote

The Surface Properties of WC-Co-Cr Based Coatings Deposited by High Velocity Oxygen Fuel Spraying

100%
Ozbek Y., Canikoğlu N., İpek M.
Acta Physica Polonica A
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2017
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vol. 131
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issue 1
186-189
EN
The aim of this research was to investigate microstructural and mechanical properties of the WC-Co-Cr coatings by high velocity oxygen fuel spraying. Woka 3653 (WC10Co4Cr) powder was used as coating material. This powder is widely used as a tribological coating material providing a combination of high toughness, high hardness, and good strength. The coatings were produced for the different high velocity oxygen fuel spraying parameters. The treated samples were characterized by using scanning electron microscopy/energy dispersive X-ray spectrometry and X-ray diffractometry. Microhardness measurements were executed to evaluate the mechanical properties of the coatings. Also the wear performance of the coatings was investigated. The scanning electron microscopy and energy dispersive X-ray spectrometry analyses were applied to worn surfaces. The results indicated that the coating shows slightly higher microhardness and better abrasive wear resistance than the conventional counterpart.
2
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Changes in Microstructure of Air Plasma Sprayed M-CrAlY Coatings After Short Thermal Exposure in Argon Atmosphere

100%
Čelko L., Řičánková V., Klakurková L., Podrábský T., Dvořáček E., Švejcar J.
Acta Physica Polonica A
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2011
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vol. 120
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issue 2
336-339
EN
Conventional air plasma spray technique and two powders, NiCrAlY and CoNiCrAlY, were used to produce the M-CrAlY type of coating on the Inconel 713LC substrate. Two phase coatings, consisting of Ni and/or Co solid solution and NiAl intermetallic phase, were produced. A certain amount of imperfectly melted powder particles, voids and aluminium oxide was also present. After air plasma spraying the coatings were annealed at widely ranging temperatures (650, 800, 1000 and 1150°C) for two hours in argon-flow atmosphere. It was found that the temperature significantly affects the microstructure of resulting coatings. The oxide scale was formed by internal oxidation in a coating region primarily at higher temperatures. In this case, aluminium was depleted from the NiAl phase within the coating region and the Ni, Co, Cr solid solutions and the aluminium oxide started to form rapidly. No interaction was observed after the short thermal exposure below the substrate surface. The microstructure of coatings was recorded by scanning electron microscope. Coating thickness, amount of voids and oxide scale were measured by means of image analysis. The concentration of phases was estimated by energy dispersive microanalysis.
3
Content available remote

The Mechanical Properties and Wear Resistance of HVOF Sprayed WC-Co Coatings

100%
Özbek Y., Canikoğlu N., İpek M.
Acta Physica Polonica A
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2016
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vol. 129
|
issue 4
600-603
EN
In this work, the Woka 5810 powders (88% tungsten carbide-12% cobalt) were used to produce coating by high velocity oxy-fuel spraying. WC-Co is widely used as a tribological coating material providing a combination of high toughness, high hardness, and good strength. The treated samples were characterized by using optical micrograph, stereo microscope and scanning electron microscopy, X-ray diffractometry, and microhardness tests. Also the wear performance of the coatings was investigated. The results indicated that the coating shows slight higher microhardness and better abrasive wear resistance than the conventional counterpart. The friction coefficient of coating was low. The scanning electron microscopy and energy dispersive spectroscopy analyses were applied to worn surfaces.
4
Content available remote

Surface Morphology, Structural and Optical Properties of MgO Films Obtained by Spray Pyrolysis Technique

63%
Diachenko O., Opanasuyk A., Kurbatov D., Opanasuyk N., Kononov O., Nam D., Cheong H.
Acta Physica Polonica A
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2016
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vol. 130
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issue 3
805-810
EN
X-ray diffraction, atomic force microscopy, field emission scanning electron microscopy, UV-visible photometry, and photoluminescence measurements were used to investigate the surface morphology and structural and optical properties of MgO films. Magnesium oxide films deposited by the spray pyrolysis technique were studied. The substrate temperature was varied from T_{s} = 643 K to 693 K. Magnesium chloride hexahydrate (MgCl₂·6H₂O), dissolved in deionized water, was used as the precursor solution. It was established that the single phase films crystallize into a cubic structure with very fine crystallite size (about 2 nm). The optical band gaps of the samples were varied from 3.64 eV to 3.70 eV. Also, the films have a high level of transmittance of 90%. Photoluminescence spectra show the emission peaks at approximately 412 nm (3.00 eV) and 524 nm (2.38 eV). The peak with the energy of 3.00 eV is ascribed to holes trapped in magnesium ion vacancies acting as acceptors (F⁺ center). The broad emission peak at 524 nm is related to the presence of defects (F¯ centers) associated with oxygen ion vacancies.
5
Content available remote

Effect of Bondcoat Thickness on High Temperature Hot Corrosion of ZrO₂-8Y₂O₃ Thermal Barrier Coating

63%
Qureshi I., Shahid M., Khan A.
Acta Physica Polonica A
|
2015
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vol. 128
|
issue 2B
B-314-B-316
EN
Thermal barrier coatings (TBCs) are widely used for industrial and aero turbines. The use of residual fuel oil is well known due to economic reasons, which causes hot corrosion. Hot corrosion over extended exposures reduces durability. Therefore, there is a requirement to develop new design approaches for TBCs in order to operate under hot corrosion environment. In this paper, the effect of bond coat thickness on the hot corrosion resistance was studied. Hot corrosion test were carried out in 50 wt.% Na₂So₄+50 wt.% V₂O₅ molten salt at 950°C for 50 hours. The characterizations of the coatings included X-ray diffraction analysis, scanning electron microscopy and optical microscope. Results indicated that TBCs with thick bond coat exhibited superior hot corrosion resistance to the TBCs with conventional bond coat.
6
Content available remote

Cavitation Damage Behavior in Seawater for Al-Mg Alloy Arc Thermal Spray Coating with Mg Content

63%
Park I., Kim S.
|
EN
Al arc thermal spray coating materials are widely used to prevent the corrosion of steel structure materials in marine environment. To improve the durability of the Al alloy thermal spray coating layer, Al-Mg alloy arc thermal spray coating was performed with different Mg contents. Furthermore, the cavitation experiment was performed in natural seawater to evaluate the durability of the thermal spray coating layer, and the damaged surface was analyzed with a scanning electron microscope and a 3D microscope. As a result, the durability of the Al-Mg alloy thermal spray coating layer improved by the addition of Mg, and the Al-3%Mg thermal spray coating layer presented the best characteristics.
7
Content available remote

Peculiarities of Deposition Times on Gas Sensing Behaviour of Vanadium Oxide Thin Films

51%
Bagheri Khatibani A., Abbasi M., Rozati S.
Acta Physica Polonica A
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2016
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vol. 129
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issue 6
1245-1251
EN
The importance of vanadium oxide in solid state science as a semiconductor encouraged us to prepare and investigate its microstructure and surface properties related to gas sensing characteristics. Hence, vanadium oxide thin films were deposited by spray pyrolysis method. The prepared films were placed in an electric circuit and the sensing characteristics of these films to ethanol vapors were studied. It was possible to find correlations between nanostructure and electrical properties of the obtained thin films and to optimize conditions of its synthesis. By X-ray diffraction, field emission scanning electron microscopy, and atomic force microscopy, the structure of the deposited films was determined. Based on atomic force microscopy results, the fractal analysis showed a decreasing trend of the fractal dimension (the slope of the log (perimeter) vs. log (area)) versus the deposition time. It was found that the film growth and gas response were affected by the deposition time. The operating temperature of the sensor was optimized for the best gas response. In accordance with our findings, the film deposited at the lowest deposition time (20 min) had the highest sensing response to ethanol.
8
Content available remote

High Temperature Oxidation of Spark Plasma Sintered and Thermally Sprayed FeAl-Based Iron Aluminides

51%
Haušild P., Karlík M., Skiba T., Sajdl P., Dubský J., Palm M.
Acta Physica Polonica A
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2012
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vol. 122
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issue 3
465-468
EN
The presented work deals with the oxidation resistance of spark plasma sintered and thermally sprayed FeAl-based intermetallics. Gas-atomized binary single phase Fe-43(at.%)Al and dual phase Fe-55(at.%)Al powders were used for spark plasma sintering and/or thermal spraying. Coatings were deposited by two different plasma spray technologies - gas and water stabilized plasma guns. The prepared samples were exposed to oxidation in artificial air at 700°C. The mass gain was measured during oxidation at 700C up to 1000 h. Microstructures, phase and chemical compositions of the formed scales were characterized after the exposition by means of scanning electron microscopy, X-ray diffraction and electron spectroscopy for chemical analysis (X-ray photoelectron spectroscopy).
9
Content available remote

Effects of Microstructural Transformation in TBCs Consisting of NiCrAlY Metallic Bond Coat and YSZ Ceramic Top Coat after Oxidation at 900°C

51%
Parlakyigit A., Karaoglanli A.
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vol. 125
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issue 2
232-234
EN
Thermal barrier coatings are applied to aeronautical and industrial gas turbine components to protect from detrimental effects of hot gases. Thermal barrier coating systems are generally composed of a substrate material, an oxidation resistant metallic bond coat, and a thermal protective ceramic-based topcoat. Additionally, thermally grown oxide layer is formed at ceramic/bond coat interface as a result of exposure of bond coat to high temperature. Oxidation mechanism is one of the major failure mechanisms of thermal barrier coatings. Thermally grown oxide layer plays significant role as a oxygen barrier, but rapid thickening of thermally grown oxide leads to spallation failure of thermal barrier coatings. In this study, thermally grown oxide growth behavior was investigated at isothermal oxidation condition to evaluate durability of the thermal barrier coating system. The thermal barrier coating system consists of yttria stabilized zirconia (YSZ) topcoat and NiCrAlY bond coat deposited on Inconel 718 superalloy with atmospheric plasma spray technique. After coating process, specimens were exposed to 900C air atmosphere for different periods up to 50 h. Ceramic/bond coat interface and thermally grown oxide layer were examined using scanning electron microscopy analysis. Besides, porosity contents and microhardness measurements were carried out to determine strength of coating. The results showed that thickness of thermally grown oxide layer increased and porosity rates of ceramic layer decreased with the effect of oxidation. Accordingly, the ceramic layer hardness increased due to high temperature effect.
10
Content available remote

Corrosion Resistance of Tin Coatings Deposited by Different Methods

45%
Winnicki M., Rutkowska-Gorczyca M., Baszczuk A., Małachowska A., Piwowarczyk T., Ambroziak A.
Acta Physica Polonica A
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2016
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vol. 130
|
issue 4
1155-1157
EN
This article describes the study of corrosion resistance of tin coatings deposited onto aluminum alloy substrates using the low pressure cold spraying and electroplating methods. The chemical corrosion resistance was examined using the Kesternich and cyclic salt spray tests inside SO₂ and NaCl climate chambers, respectively. The selected tests allowed simulation of the conditions of the coatings during service. The results were satisfactory for low pressure cold spraying coatings. Coatings produced by electroplating exhibit substantial corrosive losses due to their method of application and low thickness. Evaluation of corrosion were carried out by analyzing changes in the microstructure. Additionally, the physicochemical tests were carried out using X-ray diffraction to verify corrosion changes on the coatings surface.
11
Content available remote

Effect of Boric Acid Content on the Structural and Optical Properties of MnS Films Prepared by Spray Pyrolysis Technique

45%
Bedır M., Öztaş M., Çelik S., Özdemır T.
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vol. 126
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issue 3
840-845
EN
Boron doped MnS films were obtained by the spray pyrolysis method using the boric acid (H_3BO_3) as dopant source at a substrate temperature of 350°C. The spray pyrolysis method has a wide range of application areas with a low cost well-suited for the manufacture of solar cells. The properties of boron doped MnS films were investigated as a function of doping concentration. The X-ray analysis showed that the films were polycrystalline fitting well with a hexagonal structure and have preferred orientation in the [002] direction. The optical band gap of the undoped and boron doped MnS films were found to vary from 3.38 to 3.20 eV. The changes observed in the energy band gap and structural properties of the films related to the boric acid concentration are discussed in detail.
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