Number of found documents: 334
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Mechanical properties of plasma sprayed layers of NiAl10 and NiAl40 on AZ91 alloy
Kubatík, Tomáš František; Brodil, R.; Ctibor, Pavel; Průša, F.; Brožek, Vlastimil
2017 - 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, 2017

Large displacement and deformation measurement by frequency sweeping digital holography
Psota, P.; Lédl, Vít; Kaván, František; Matoušek, O.; Doleček, R.
2017 - English
Recently, a digital holographic method called Frequency Sweeping Digital Holography (FSDH) for high precision measurements of surface topography of mechanical parts has been introduced. The greatest advantage of the presented FSDH is the fact that the measurement is absolute. i.e. optical path difference is independently retrieved in every single pixel. This approach can therefore be used also for measurement of large displacements and deformation. FSDH is particularly suitable in cases where the common digital holographic methods fail due to e.g. 2π unambiguity problem or speckle decorrelation. Measurement method principles, setup details, an some features of the method are discussed.\n Keywords: Digital holography; Digital holographic interferometry; Displacement measurement; Absolute measurements Available at various institutes of the ASCR
Large displacement and deformation measurement by frequency sweeping digital holography

Recently, a digital holographic method called Frequency Sweeping Digital Holography (FSDH) for high precision measurements of surface topography of mechanical parts has been introduced. The greatest ...

Psota, P.; Lédl, Vít; Kaván, František; Matoušek, O.; Doleček, R.
Ústav fyziky plazmatu, 2017

Black Chromia Plating for the Solar Radiation Absorbers
Brožek, Vlastimil; Březina, Václav; Brom, Petr; Kubatík, Tomáš František; Vilémová, Monika; Mastný, L.; Novák, M.
2016 - English
Black chromia layers were produced on copper, zirconium and aluminium substrates. These layers are aimed to serve as solar collectors. Efficiency of the layers during UV-VIS, UV radiation and WSP® plasma torch radiation is described. The chromia layers were prepared by a new procedure, i.e. deposition of ammonium dichromate solution using plasma torch or so called Liquid Precursor Plasma Spraying (LPPS). Solution of ammonium dichromate is fed into plasma stream, where dissociation takes place under temperatures of 4000 K – 25000 K. Up to nanometric oxide particles can be produced; the resulting size is dependent on solution concentration and feeding nozzle diameter. The particles impact on substrate and form coating. Using 2 wt.% to 5 wt.% solution of ammonium dichromate and feeding nozzle of 0.2 mm in diameter is the size of produced chromia particles about 6 µm which results in formation of 2 µm to 3 µm thick coating, i.e. according to the theory an optimal thickness 2.5 um for absorption layers, necessary condition for formation energy traps for IR radiation emitters up to 100°C. Moreover, black chromia coating is a suitable corrosion barrier of metallic substrates. \n\n Keywords: Solar collector; black chromia; plasma spraying; ceramic coatings Available at various institutes of the ASCR
Black Chromia Plating for the Solar Radiation Absorbers

Black chromia layers were produced on copper, zirconium and aluminium substrates. These layers are aimed to serve as solar collectors. Efficiency of the layers during UV-VIS, UV radiation and WSP® ...

Brožek, Vlastimil; Březina, Václav; Brom, Petr; Kubatík, Tomáš František; Vilémová, Monika; Mastný, L.; Novák, M.
Ústav fyziky plazmatu, 2016

Black Chromia Coatings on Metal Tubes for the Solar Collectors
Brožek, V.; Mastný, L.; Novák, M.; Vilémová, Monika; Kubatík, Tomáš František
2016 - English
This paper describes the results of the first phase of the study preparation, structure and properties of coatings modification of black chromium oxide on copper, aluminium, iron and zirconium tubes for solar collectors. The coatings are prepared by plasma spraying of liquid chromate method which is known as liquid precursor plasma spraying. Coatings have the function of an energy trap for thermal radiation wavelengths of 1 μm – 3 μm i.e. in the IR region. At the same time, the coating increases the corrosion resistance of metal substrates. The nanometric structure and thickness of the coating depend of the feeding distance and the concentration of chromate precursors. For the deposition of nanometric splats of melt chromiumIII oxide, a new type of feeder that injects precursors into the water stabilized thermal plasma produced by the WSP® generator has been\ndeveloped.\n Keywords: Solar collector; black chromia; plasma spraying; suspension spraying Available at various institutes of the ASCR
Black Chromia Coatings on Metal Tubes for the Solar Collectors

This paper describes the results of the first phase of the study preparation, structure and properties of coatings modification of black chromium oxide on copper, aluminium, iron and zirconium tubes ...

Brožek, V.; Mastný, L.; Novák, M.; Vilémová, Monika; Kubatík, Tomáš František
Ústav fyziky plazmatu, 2016

Spectroscopic Study of Underwater Electrical Discharge Generated by Nanosecond Pulses.
Pongrác, Branislav; Šimek, Milan; Babický, Václav; Člupek, Martin; Lukeš, Petr
2016 - English
Underwater electrical discharge generated by high voltage pulses with nanosecond duration (~110 kV amplitude on the needle, ~5 ns duration (FWHM), 1 Hz repetition rate) has been investigated. Time–resolved optical emission spectroscopy showed different emission spectra profile of the ns–pulsed discharge compared to the μs–pulsed discharges investigated previously. Some characteristic peaks typical for water discharges (Hα, OI) were clearly visible in the spectra. In addition, the integral light emission of the discharge was recorded by photomultiplier tube. Keywords: nanosecond discharge; water discharge; time-resolved emission spectroscopy Available at various institutes of the ASCR
Spectroscopic Study of Underwater Electrical Discharge Generated by Nanosecond Pulses.

Underwater electrical discharge generated by high voltage pulses with nanosecond duration (~110 kV amplitude on the needle, ~5 ns duration (FWHM), 1 Hz repetition rate) has been investigated. ...

Pongrác, Branislav; Šimek, Milan; Babický, Václav; Člupek, Martin; Lukeš, Petr
Ústav fyziky plazmatu, 2016

Corrosion behavior of plasma coatings CuAl10 and CuAl50 on magnesium alloy AZ 91
Kubatík, Tomáš František; Stoulil, J.; Stehlíková, K.; Slepička, P.; Janata, Marek
2016 - English
The most common magnesium alloy AZ 91 is widely used as a structural material, but its use is limited at higher temperatures and high humidity. Plasma spraying is a technology that allows to prepare protective metallic and non-metallic coatings on a wide variety of substrates including magnesium and its alloys. In this study, CuAl10 and CuAl50 were plasma sprayed on magnesium alloy AZ 91 with the aim to study corrosion resistance of the plasma sprayed coatings. The corrosion resistance of layers was evaluated by the method of electrochemical potentiodynamic measurement as well as long-term corrosion tests in a condensation chamber with 0.5 mol\nNaCl at the temperature of 35 °C for 1344 hours. Layers with 1, 2, 5 passes and passes of CuAl10 with the thickness ranging from 75 to 716 mm and CuAl50 with the thickness ranging from 64 to 566 mm were prepared. The increased corrosion velocity was observed in the case of thin layers of 2 and 5 passes due to the development of a galvanic corrosion couple. The CuAl10 layer prepared with ten passes has an outstanding corrosion resistance. Keywords: magnesium alloy AZ 91; plasma spraying; corrosion resistance Available at various institutes of the ASCR
Corrosion behavior of plasma coatings CuAl10 and CuAl50 on magnesium alloy AZ 91

The most common magnesium alloy AZ 91 is widely used as a structural material, but its use is limited at higher temperatures and high humidity. Plasma spraying is a technology that allows to prepare ...

Kubatík, Tomáš František; Stoulil, J.; Stehlíková, K.; Slepička, P.; Janata, Marek
Ústav fyziky plazmatu, 2016

Deposition of Titania from Solution by Hybrid Water-Stabilized Plasma Torch
Mušálek, Radek; Medřický, Jan; Tesař, Tomáš; Kotlan, Jiří; Lukáč, František
2016 - English
Thermal spraying with liquid feedstock presents a novel route for deposition of functional coatings. In this study, possibility of preparation of titania coatings from solution by hybrid water stabilized plasma torch is presented. Coatings were prepared from solution of titanium isopropoxide Ti[OCH(CH3)2]4 in anhydrous ethanol. Fragmentation of feedstock stream in the plasma jet was monitored by shadowgraphy. Deposition was carried out on steel samples mounted to the cooled rotating carousel. Cross-sectional images from SEM microscope showed successful formation of the deposit with dual morphology consisting of fine feather-like features combined with bigger droplets. X-ray diffraction revealed formation of nanometric rutile crystallites. Keywords: Thermal spraying; plasma spraying; titania; solution; liquid feedstock Available at various institutes of the ASCR
Deposition of Titania from Solution by Hybrid Water-Stabilized Plasma Torch

Thermal spraying with liquid feedstock presents a novel route for deposition of functional coatings. In this study, possibility of preparation of titania coatings from solution by hybrid water ...

Mušálek, Radek; Medřický, Jan; Tesař, Tomáš; Kotlan, Jiří; Lukáč, František
Ústav fyziky plazmatu, 2016

Formation of RONS in cold air plasma activazed water and their effects on cell membranes of Escherichia coli
Tarabová, B.; Machala, Z.; Doležalová, Eva; Lukeš, Petr
2016 - English
In this work, we focused on the detection of secondary reactive oxygen and nitrogen species (RONS) formed by cold plasma induced gas-liquid chemistry in air discharge activated water and liquids. Plasma induced chemical changes in plasma activated water (PAW) were correlated with the antibacterial effect, sublethal injury of bacterial cells and peroxidation of membrane lipids. The contribution of the electric field induced by the plasma treatment was evaluated by the detection of membrane permeabilization. The bactericidal effects of direct (plasma and PAW) and indirect (only PAW) treatments were compared with long-term preservation of the PAW with its antibacterial properties Keywords: cold air plasma; plasma activated water; sublethal injury; lipoperoxidation Available at various institutes of the ASCR
Formation of RONS in cold air plasma activazed water and their effects on cell membranes of Escherichia coli

In this work, we focused on the detection of secondary reactive oxygen and nitrogen species (RONS) formed by cold plasma induced gas-liquid chemistry in air discharge activated water and liquids. ...

Tarabová, B.; Machala, Z.; Doležalová, Eva; Lukeš, Petr
Ústav fyziky plazmatu, 2016

DYNAMICS OF ACCELERATING STREAMER IN BARRIER DISCHARGE IN AIR.
Hoder, T.; Bonaventura, Z.; Prukner, Václav; Šimek, Milan
2016 - English
An accelerating streamer in barrier discharge is generated in 10 torr pressure air. Using the complex voltage waveform, the stable and reproducible discharge is triggered. From the ratio of two spectral bands of molecular nitrogen the electric field is determined in 2D. These results are well resolved in time and space thus suitable as a benchmark for computation of the streamer initiated plasma-chemistry in air. Keywords: streamer; air; electric field Available at various institutes of the ASCR
DYNAMICS OF ACCELERATING STREAMER IN BARRIER DISCHARGE IN AIR.

An accelerating streamer in barrier discharge is generated in 10 torr pressure air. Using the complex voltage waveform, the stable and reproducible discharge is triggered. From the ratio of two ...

Hoder, T.; Bonaventura, Z.; Prukner, Václav; Šimek, Milan
Ústav fyziky plazmatu, 2016

Arc–Anode Attachment Area in DC Arc Plasma Torch at Low Pressure
Ondáč, Peter; Mašláni, Alan; Hrabovský, Milan
2016 - English
Studying the processes in the anode attachment area of a DC arc plasma torch helps to extend the lifetime of the anode, stabilize the plasma flow for plasma spraying and better understand the movement of the anode attachment. In this work, such processes were studied at low pressure, by a non-disturbing method, using a high-speed camera and a high voltage probe. We also found pressure ranges, in which the following transitions were observed: the constricted/diffuse anode attachment, and subsonic/supersonic plasma jet\n Keywords: Arc Plasma Torch; Arc–Anode Attachment; Low Pressure Available at various institutes of the ASCR
Arc–Anode Attachment Area in DC Arc Plasma Torch at Low Pressure

Studying the processes in the anode attachment area of a DC arc plasma torch helps to extend the lifetime of the anode, stabilize the plasma flow for plasma spraying and better understand the movement ...

Ondáč, Peter; Mašláni, Alan; Hrabovský, Milan
Ústav fyziky plazmatu, 2016

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