Number of found documents: 410
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The role of microstructure on wettability of plasma sprayed yttria stabilized zirconia coatings
Komarov, P.; Čelko, L.; Remešová, M.; Skorokhod, K.; Jech, D.; Klakurková, L.; Slámečka, K.; Mušálek, Radek
2018 - English
Atmospheric plasma spraying utilizing initial powder materials in micrometric size has been successfully used for various applications in different fields of the industry over the past several decades. Nowadays, the new trend in plasma spraying is to use sub-micron or nano-sized powder feedstocks in the form of colloidal suspension. This relatively new technology enables to obtain specific types of dense vertically cracked, fully dense or columnar microstructure. The aim of this work is to investigate the influence of coatings microstructure and topography on its water wetting properties. Two different microstructures, i.e. lamellar and columnar, were sprayed from chemically the same yttria-stabillized zirconia (YSZ) ceramics powders by the means of conventional atmospheric plasma spray and suspension hybrid water stabilized plasma spray techniques, respectively. Microstructural and phase composition of the initial powders and as-sprayed coatings were investigated using optical microscopy, scanning electron microscopy and X-ray diffraction techniques. Topography of coatings surface was measured by means of non-contact optical profilometry. The YSZ coatings wettability was evaluated based on water droplet contact angle using Sessile droplet method. The coatings microstructure reveals the important role in the change of droplet contact angle, where lamellar microstructure was found close to hydrophilic-hydrophobic transition and columnar microstructure was found superhydrophobic Keywords: Contact angle; Plasma spraying; Sessile drop method; Water; Yttria stabilized zirconia Available at various institutes of the ASCR
The role of microstructure on wettability of plasma sprayed yttria stabilized zirconia coatings

Atmospheric plasma spraying utilizing initial powder materials in micrometric size has been successfully used for various applications in different fields of the industry over the past several ...

Komarov, P.; Čelko, L.; Remešová, M.; Skorokhod, K.; Jech, D.; Klakurková, L.; Slámečka, K.; Mušálek, Radek
Ústav fyziky plazmatu, 2018

Combined coatings against mechanical wear and corrosion low carbon steel
Brožek, Vlastimil; Pokorný, P.; Kolísko, J.; Vokáč, M.; Mastný, L.; Stoulil, J.
2018 - English
In this study, special ceramic coatings were prepared on low carbon steel (1.0060 - EN 10027-2) via the plasma spraying technique using a WSP®-H plasma generator with output of up to 40 kg/h of aluminum oxide. Corundum coatings were deposited directly on the surface of steel plungers equipped with an anti-corrosion interlayer of zinc phosphate. Coating adhesion properties were tested using pin-off tests (modified ISO 4624) and reached a maximum value of 26 MPa. Corrosion resistance was evaluated by measurements of impedance spectra in the 100 kHz - 10 mHz range in a water solution of sodium sulfate. The capacity of electric double-layer varied depending on the porosity and thickness of the coating. Low-porosity coatings of >1.5 mm thickness had RCT 1.29·105 Ω·m2. The abrasive resistance of coatings was measured by rotary/machining test with SiC cutting knives, using a downforce of 50 kg·cm-2. Abrasion losses decreased with the quality of finish - starting at 0.00266 g cm-2 min-1 down to virtually zero losses after polishing the surface below Ra = 0.55 micro m. Keywords: Abrasion; Ceramic coatings; Corrosion resistance; Plasma spraying; Steel phosphating Available at various institutes of the ASCR
Combined coatings against mechanical wear and corrosion low carbon steel

In this study, special ceramic coatings were prepared on low carbon steel (1.0060 - EN 10027-2) via the plasma spraying technique using a WSP®-H plasma generator with output of up to 40 kg/h of ...

Brožek, Vlastimil; Pokorný, P.; Kolísko, J.; Vokáč, M.; Mastný, L.; Stoulil, J.
Ústav fyziky plazmatu, 2018

Suspension plasma spraying of sub-stoichiometric titania by hybrid water/argon stabilized plasma torch
Mušálek, Radek; Ctibor, Pavel; Medřický, Jan; Tesař, Tomáš; Kotlan, Jiří; Lukáč, František
2018 - English
In this study, suspension plasma spraying of sub-stoichiometric titania was attempted using hybrid water/argon stabilized plasma torch (WSP-H). Porous coatings with fine cauliflower-like columnar microstructure were successfully deposited in two separate experiments with different power levels of the plasma torch. In both cases, high solid-load content (40 wt. %) of the water-based suspension resulted in considerable coating thickness increase per deposition cycle. Coating annealing and partial remelting of the surface asperities were also achieved by additional pass of plasma torch in front of the coating surface. According to X-ray diffraction, all coatings consisted dominantly of rutile phase. Detailed microscopic observation of the as-sprayed and annealed deposits showed that the local coloration of the coating (ranging from dark blue to beige) was driven by the local overheating of the rough coating surface which could also promote the oxygen intake. Moreover, sample annealing was also observed to increase the sample reflectivity as observed by UV-VIS-NIR scanning spectrophotometry Keywords: Liquid feedstock; Plasma spraying; Suspension; Thermal spraying; Titania; WSP-H Available at various institutes of the ASCR
Suspension plasma spraying of sub-stoichiometric titania by hybrid water/argon stabilized plasma torch

In this study, suspension plasma spraying of sub-stoichiometric titania was attempted using hybrid water/argon stabilized plasma torch (WSP-H). Porous coatings with fine cauliflower-like columnar ...

Mušálek, Radek; Ctibor, Pavel; Medřický, Jan; Tesař, Tomáš; Kotlan, Jiří; Lukáč, František
Ústav fyziky plazmatu, 2018

Mechanical properties of plasma sprayed layers of NiAl10 and NiAl40 on AZ91 alloy
Kubatík, Tomáš František; Brodil, R.; Ctibor, Pavel; Průša, F.; Brožek, Vlastimil
2018 - English
In this work, plasma coatings of NiAl10 and NiAl40 on magnesium alloy AZ91 substrate were prepared by the hybrid plasma spraying system WSP®-H 500. The both plasma sprayed coatings of NiAl10 and NiAl40 have metallurgical bond. The thicknesses of microstructures in the cross-section of NiAl10 and NiAl40 plasma sprayed coatings prepared by 9 passes were 374 and 440 μm respectively. Adhesion test of plasma sprayed layers was performed using a modified ASTM C 633 standard. The tensile adhesion strength values are 24.7 MPa for NiAl10 coatings and 12.3 MPa for NiAl40 coatings. Abrasion resistance according to Slurry Abrasion Response (SAR) test of NiAl40 layers had similar values (0.12 g/cm2)in a comparison with the uncoated AZ91 (0.126 g/cm2). Layers NiAl10 had greater weight losses (0.175 g/cm2) than uncoated AZ91. Microhardness of plasma coating of NiAl40 is several times greater than microhardnesses of plasma coating of NiAl10 and uncoated substrate AZ91 Keywords: Adhesion strength; Nickel alloys; Plasma spraying; Wear resistance Available at various institutes of the ASCR
Mechanical properties of plasma sprayed layers of NiAl10 and NiAl40 on AZ91 alloy

In this work, plasma coatings of NiAl10 and NiAl40 on magnesium alloy AZ91 substrate were prepared by the hybrid plasma spraying system WSP®-H 500. The both plasma sprayed coatings of NiAl10 and ...

Kubatík, Tomáš František; Brodil, R.; Ctibor, Pavel; Průša, F.; Brožek, Vlastimil
Ústav fyziky plazmatu, 2018

Alternative Methods of Permeation Barriers Preparation
Veverka, Jakub; Matějíček, Jiří
2018 - English
Permeation barriers represent one of the crucial fields in materials development for thermonuclear fusion. Primary objective of the barriers is to suppress the permeation of hydrogen isotopes (mainly tritium) from future thermonuclear fusion facilities. Secondary objective is to reduce their retention in structural materials. Expected reactor conditions put high demands on the material, as well as on the final barrier quality. Key properties are tritium permeation reduction, absence of defects (especially cracks), high-temperature stability and corrossion resistance, and compatibility with structural materials (mostly ferritic-martensitic steels). Thin nitride layers, identified as promising permeation barriers, were prepared by diffusion-based nitridation and physical vapour deposition (PVD), and characterized. Keywords: Permeation barriers; Nitride layers; PVD coating; Permeation measurement Available at various institutes of the ASCR
Alternative Methods of Permeation Barriers Preparation

Permeation barriers represent one of the crucial fields in materials development for thermonuclear fusion. Primary objective of the barriers is to suppress the permeation of hydrogen isotopes (mainly ...

Veverka, Jakub; Matějíček, Jiří
Ústav fyziky plazmatu, 2018

Application of Electric Probes for Study of Structure of Thermal Plasma Jet.
Hurba, Oleksiy; Hrabovský, Milan
2017 - English
Thermal plasma at atmospheric pressure was investigated. Electric probes and doable probe used as relatively simple and efficient tool for diagnostic of structure of flow field in thermal plasma jet. Were defined plasma potential and boundaries of the conducting region and their changing for the diferent operating modes of plasma torch. Keywords: Electric probes; double probe; thermal; plasma jet Available at various institutes of the ASCR
Application of Electric Probes for Study of Structure of Thermal Plasma Jet.

Thermal plasma at atmospheric pressure was investigated. Electric probes and doable probe used as relatively simple and efficient tool for diagnostic of structure of flow field in thermal plasma jet. ...

Hurba, Oleksiy; Hrabovský, Milan
Ústav fyziky plazmatu, 2017

Sub-Nanosecond Laser Induced Plasma as Water Window Radiation Source.
Vrbová, M.; Vrba, Pavel
2017 - English
Laser plasma created in a krypton gas puff target is studied as a source of radiation in the water window spectral range (lambda= 2.3 - 4.4 nm). The spatial development of the plasma induced by a sub-nanosecond Nd:YAG laser pulse focused on the gas puff target is modeled using 2d RMHD code Z*. Space-time distributions of plasma quantities, namely electron temperature, electron density, mass density and plasma expansion velocity were evaluated. Instantaneous spectra during the laser pulse and during plasma decay period are also calculated. Temporal evolutions of the krypton ions relative populations prove that ions from Kr21+ and Kr22+ are responsible for dominant spectral intensity emitted at a wavelength around lambda= 3 nm. Evaluated time resolved spectra are compared with time integrated spectra obtained experimentally. Keywords: RMHD simulations; gas puff; laser plasma water window sources Available at various institutes of the ASCR
Sub-Nanosecond Laser Induced Plasma as Water Window Radiation Source.

Laser plasma created in a krypton gas puff target is studied as a source of radiation in the water window spectral range (lambda= 2.3 - 4.4 nm). The spatial development of the plasma induced by a ...

Vrbová, M.; Vrba, Pavel
Ústav fyziky plazmatu, 2017

Properties of hydroxyapatite surface deposited by plasma spray technologies
Matějková, M.; Čížek, Jan; Mušálek, Radek; Dlouhý, I.
2017 - English
The surface properties of hydroxyapatite (HA) deposited on the Ti-6Al-4V substrates by plasma spraying were studied. Two different plasma spray technologies (hybrid plasma spray system (WSP-H) and conventional atmospheric plasma spray technology (APS)) and two various feedstock (suspension for WSP-H and powder for APS) were used for deposition of HA layers potentially suitable for bio-applications. The layers properties (thickness, chemical and phase composition) and coating-substrate interface quality were analyzed. The XRD analysis showed formation of small amount of new phases (TTCP and CaO) in layers deposited by WSP-H. Better coating-substrate interface quality of samples prepared by WSP-H was observed. The results showed the deposition of HA through liquid feedstock via WSP-H as a promising route, complementing the traditional APS powder deposition in the near future. Keywords: hydroxyapatite; hybrid water-stabilized plasma spray; atmospheric plasma spray technology Fulltext is available at external website.
Properties of hydroxyapatite surface deposited by plasma spray technologies

The surface properties of hydroxyapatite (HA) deposited on the Ti-6Al-4V substrates by plasma spraying were studied. Two different plasma spray technologies (hybrid plasma spray system (WSP-H) and ...

Matějková, M.; Čížek, Jan; Mušálek, Radek; Dlouhý, I.
Ústav fyziky plazmatu, 2017

Deformation of thin self-standing mask at inhomogeneous irradiation.
Koláček, Karel; Schmidt, Jiří; Frolov, Oleksandr; Štraus, Jaroslav; Chalupský, Jaromír; Choukourov, A.
2017 - English
Flatness of the mask is one of key features influencing the quality of image. Among factors that can affect mask flatness belongs inhomogeneous illumination. This does not apply to lithography, but to experiments that use only discrete parts of mask e.g. for nanostructuring or other type of material research. It is shown that even single EUV laser shot (laser wavelength ~46.9 nm, pulse duration ~1.5 ns, focused pulse energy ~20 .mu.J, peak fluency 48 J/cm2) not only deforms the mask, but also changes mask-substrate distance. In our case two kinds of grids (one circular with rectangular windows 7.5x7.5 μm and bars 5 micro m (period 12.5x12.5 micro m), other rectangular with rectangular windows 3.2x1.2 μm and bars 0.8 micro m (period 4x2 micro m)) were attached to PMMA substrate and exposed to one or five superimposed focused laser shots. The mask (grid) deformation was inferred from the changes of diffraction pattern engraved into PMMA. Keywords: interaction of XUV radiation with solid surface; nanostructuring; nanopatterning; XUV diffraction Available at various institutes of the ASCR
Deformation of thin self-standing mask at inhomogeneous irradiation.

Flatness of the mask is one of key features influencing the quality of image. Among factors that can affect mask flatness belongs inhomogeneous illumination. This does not apply to lithography, but to ...

Koláček, Karel; Schmidt, Jiří; Frolov, Oleksandr; Štraus, Jaroslav; Chalupský, Jaromír; Choukourov, A.
Ústav fyziky plazmatu, 2017

The role of pre-ionization on EUV capillary laser profile.
Štraus, Jaroslav; Schmidt, Jiří; Koláček, Karel; Frolov, Oleksandr
2017 - English
The profile of EUV capillary laser beam was believed to be an annulus and a corresponding theory for its explanation was generally accepted. Nevertheless, our recent detailed observation shows, that the laser profile can be remarkably influenced by the parameters of pre-pulse, serving for working gas pre-ionisation before introduction the main current into the capillary. The examples of possible profile shapes and corresponding parameters are presented. Keywords: Pre-pulse; capillary XUV laser beam profile Available at various institutes of the ASCR
The role of pre-ionization on EUV capillary laser profile.

The profile of EUV capillary laser beam was believed to be an annulus and a corresponding theory for its explanation was generally accepted. Nevertheless, our recent detailed observation shows, that ...

Štraus, Jaroslav; Schmidt, Jiří; Koláček, Karel; Frolov, Oleksandr
Ústav fyziky plazmatu, 2017

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