Počet nalezených dokumentů: 399
Publikováno od do

Ceramic protection of anti-corrosion layers of 3-glycidyloxypropyl-triethoxysilane on steel
Pokorný, P.; Prodanović, N.; Janata, Marek; Brožek, Vlastimil
2023 - anglický
There are various variations on the problem of steel reinforcement bond strength in concrete. Along with geometrical considerations, corrosion performance of steels with varying chemical compositions in interaction with variable chemical compositions of concrete are crucial. One approach is to cover steel surfaces with organosilane compounds, which increases the reinforcement resistance to corrosion in both acidic and alkaline conditions but, on the other hand, may weaken the reinforcement bond strength on concrete. The issue is resolved by intentionally forming a thin-walled, highly adhering corundum layer that is highly porous and impregnated with 3-glycidyloxypropyltriethoxysilane. This procedure also includes testing the adhesion properties between the ceramic and the metal and the cement prior to conducting a corrosion test in a chloride environment. Klíčová slova: steel; concrete; ceramics Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Ceramic protection of anti-corrosion layers of 3-glycidyloxypropyl-triethoxysilane on steel

There are various variations on the problem of steel reinforcement bond strength in concrete. Along with geometrical considerations, corrosion performance of steels with varying chemical compositions ...

Pokorný, P.; Prodanović, N.; Janata, Marek; Brožek, Vlastimil
Ústav fyziky plazmatu, 2023

Preparation of W-Cu composites by infiltration of w skeletons review
Matějíček, Jiří
2021 - anglický
Tungsten-copper composites feature high corrosion and erosion resistance, very good thermal and electrical conductivity, low thermal expansion and good mechanical properties. They are used in a variety of demanding applications, such as arc-resistant electrodes, high voltage electrical contacts, heat sinks for integrated circuits, etc. They are also foreseen for use in plasma-facing components of fusion reactors, e.g. as a transition layer between the (refractory) plasma-facing tungsten and the (highly conductive) copper-based cooling structure. In general, high density and good bonding of the tungsten and copper phases is desired. Molten copper infiltration into tungsten preforms is among the prospective fabrication technologies - the structure and properties of the resultant composites are dependent on the specific technological parameters. In this paper, the preparation of W-Cu composites by infiltration of W skeletons is reviewed and attention is paid to the influence of these particular parameters: infiltration temperature, time and atmosphere, tungsten preform porosity, orientation and chemistry (presence or absence of other elements). Optimum parameter combinations for achieving high density and proper bonding of copper and tungsten are identified. Klíčová slova: Composites; Copper; Molten copper infiltration; Tungsten Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Preparation of W-Cu composites by infiltration of w skeletons review

Tungsten-copper composites feature high corrosion and erosion resistance, very good thermal and electrical conductivity, low thermal expansion and good mechanical properties. They are used in a ...

Matějíček, Jiří
Ústav fyziky plazmatu, 2021

High temperature corrosion behaviour of nicr-based coatings applied by twin wire arc spray technology
Lencová, K.; Vostřák, M.; Naďová, J.; Lukáč, František; Mušálek, Radek
2021 - anglický
High temperature corrosion is a serious problem related to the combustion of heavy oils with high vanadium contents. Protective overlay coatings are used to allow functioning of engineering components under extreme conditions and provide corrosion resistance to extend the component life. This article is concerned with the high temperature corrosion behaviour of two protective NiCr-based coatings and bare structural steel 1.4959 (W.nr.) in a molten salt environment of 40% Na2SO4 and 60% V2O5 at 750 °C under cyclic condition. NiCr and NiCrMoNbTa coating was deposited on steel 1.4903 (W.nr.) by Twin wire arc spray technology (TWAS). To establish the kinetics of corrosion, the thermogravimetric technique was used. The X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) techniques were used to analyse the corrosion products and determine the corrosion mechanism. The hot corrosion resistance of both coatings was better than bare steel samples. The NiCrMoNbTa coating showed better corrosion behaviour than the NiCr coating. However, also the NiCr coating provides sufficient protection to the substrate material. Klíčová slova: Heavy oils; High temperature corrosion; NiCr; NiCr-based coating; NiCrMoNbTa; Twin Wire Arc Spray; Vanadium Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
High temperature corrosion behaviour of nicr-based coatings applied by twin wire arc spray technology

High temperature corrosion is a serious problem related to the combustion of heavy oils with high vanadium contents. Protective overlay coatings are used to allow functioning of engineering components ...

Lencová, K.; Vostřák, M.; Naďová, J.; Lukáč, František; Mušálek, Radek
Ústav fyziky plazmatu, 2021

Microstructure and microhardness evaluation for NiCrAlY materials manufactured by spark plasma sintering and plasma spraying
Hulka, Iosif; Mušálek, Radek; Lukáč, František; Klečka, Jakub; Chráska, Tomáš
2020 - anglický
NiCrAlY deposited by different thermal spraying methods is commonly used as the bond coat material in thermal barrier coatings (TBCs). In the present study, two experimental coatings were deposited by hybrid water stabilized plasma (WSP-H) and radio frequency inductively coupled plasma (RF-ICP) using the same feedstock powder. Spark plasma sintering (SPS) was used to manufacture a compact NiCrAlY from the same feedstock powder as a reference material. Microstructure, internal oxidation, phase characterization and quantification of the mechanical behaviour in terms of microhardness were studied. The investigations clearly showed microstructural and mechanical differences between the NiCrAlY samples manufactured by different plasma technologies. The results confirmed that SPS and RF-ICP provide dense structures with no oxides due to the fabrication under protective atmosphere and similar mechanical properties. Thus, RF-ICP may be used for deposition of very dense coatings with microstructure and hardness comparable to compacted materials prepared by SPS. Klíčová slova: Microhardness; Microstructure; NiCrAlY; Plasma spraying; Spark plasma sintering Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Microstructure and microhardness evaluation for NiCrAlY materials manufactured by spark plasma sintering and plasma spraying

NiCrAlY deposited by different thermal spraying methods is commonly used as the bond coat material in thermal barrier coatings (TBCs). In the present study, two experimental coatings were deposited by ...

Hulka, Iosif; Mušálek, Radek; Lukáč, František; Klečka, Jakub; Chráska, Tomáš
Ústav fyziky plazmatu, 2020

Technical manual - collimator
Kredba, Jan; Steiger, Lukáš; Tomka, David; Václavík, Jan
2018 - anglický
The purpose of this document is to provide basic set of rules and instructions that allows using and maintaining of the NEOSTED collimator (COL).\nBe aware that it is not purpose of this document to provide detailed description of individual parts of the COL system. If necessary all the details and proper references can be found in [AD-2]. Klíčová slova: collimator; NEOSTED; TOPTEC; optical testing; interferometry Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Technical manual - collimator

The purpose of this document is to provide basic set of rules and instructions that allows using and maintaining of the NEOSTED collimator (COL).\nBe aware that it is not purpose of this document to ...

Kredba, Jan; Steiger, Lukáš; Tomka, David; Václavík, Jan
Ústav fyziky plazmatu, 2018

Effect of sintering temperature on microstructure and mechanical properties of AE42 magnesium alloy prepared by spark plasma sintering
Minárik, P.; Lukáč, František; Cinert, Jakub; Šašek, S.; Král, R.
2018 - anglický
Magnesium alloy AE42 was prepared by powder metallurgy technique of spark plasma sintering. The effect of sintering parameters, particularly sintering temperature, on the microstructure and mechanical strength was investigated. The gas-atomized powder was sintered at four temperatures in the temperature range of 400-550 °C. It was found that mechanical strength of the sintered samples was significantly affected by several microstructural features. Application of relatively high load during sintering caused deformation of the individual particles and consequent recrystallization depending on the processing temperature resulted in the release of internal strain and in grain growth. As a result, the evolution of the mechanical strength as a function of the sintering temperature was significantly affected by residual stress, grain size and coarsening of secondary phase particles. Klíčová slova: Magnesium; Mechanical properties; Microstructure; Spark plasma sintering Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Effect of sintering temperature on microstructure and mechanical properties of AE42 magnesium alloy prepared by spark plasma sintering

Magnesium alloy AE42 was prepared by powder metallurgy technique of spark plasma sintering. The effect of sintering parameters, particularly sintering temperature, on the microstructure and mechanical ...

Minárik, P.; Lukáč, František; Cinert, Jakub; Šašek, S.; Král, R.
Ústav fyziky plazmatu, 2018

Collimator - test readiness review
Budasz, Jiří; Kaván, František; Kredba, Jan; Lédl, Vít; Mach, Marek; Pleštil, Jan; Psota, Pavel; Steiger, Lukáš; Tomka, David; Václavík, Jan; Veselý, Martin
2018 - anglický
This document describes the test procedure applicable to the overall functional test of the NEOSTED collimator.\nThe test to be performed according to this procedure are to demonstrate the compliance of the above item to the requirements specified in the applicable document as part of the overall verification program. The test results shall be collected in a Test Report. Klíčová slova: collimator; PLC system; telescope; interferometry Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Collimator - test readiness review

This document describes the test procedure applicable to the overall functional test of the NEOSTED collimator.\nThe test to be performed according to this procedure are to demonstrate the compliance ...

Budasz, Jiří; Kaván, František; Kredba, Jan; Lédl, Vít; Mach, Marek; Pleštil, Jan; Psota, Pavel; Steiger, Lukáš; Tomka, David; Václavík, Jan; Veselý, Martin
Ústav fyziky plazmatu, 2018

Technical manual - neosted SOT test bench
Steiger, Lukáš
2018 - anglický
The purpose of this document is to provide basic set of rules and instructions that allows using and maintaining of the NEOSTED SOT test bench (BB).\nFurther detailed informations and proper references about individual parts of the BB system can be found in [AD-2, AD-3]. Klíčová slova: test bench; optical testing; collimator; neosted Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Technical manual - neosted SOT test bench

The purpose of this document is to provide basic set of rules and instructions that allows using and maintaining of the NEOSTED SOT test bench (BB).\nFurther detailed informations and proper ...

Steiger, Lukáš
Ústav fyziky plazmatu, 2018

Electric probe measurements in the anode area of a DC arc plasma torch at low pressure
Ondáč, Peter; Mašláni, Alan; Hrabovský, Milan
2018 - anglický
We measured radial profiles of the electric field, plasma electrical potential and electron temperature in the hot anode area of a hybrid water-argon DC arc plasma torch with an external anode. The measurements were made under different values of the ambient pressure, during the restrike mode with a constricted anode arc attachment or during a supersonic mode with a diffuse anode arc attachment. The results provide first experimental data on plasma electrical potential in that anode area. Klíčová slova: plasma; arc; anode; low pressure; electric probes Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Electric probe measurements in the anode area of a DC arc plasma torch at low pressure

We measured radial profiles of the electric field, plasma electrical potential and electron temperature in the hot anode area of a hybrid water-argon DC arc plasma torch with an external anode. The ...

Ondáč, Peter; Mašláni, Alan; Hrabovský, Milan
Ústav fyziky plazmatu, 2018

The effect of spark plasma sintering on the porosity and mechanical properties of Ti-15Mo alloy
Terynková, A.; Kozlík, J.; Bartha, K.; Chráska, Tomáš; Dlabáček, Zdeněk; Stráský, J.
2018 - anglický
Metastable β-titanium alloys are receiving much interest for various applications such as aircraft industry and medicine thanks to their excellent mechanical properties and biocompatibility. The common way of preparing the titanium alloys is hindered by its production costs. Powder metallurgy (PM) approach is a promising route for cost-effective fabrication of titanium alloys due to possibility of near net shaping. In this study, binary biomedical Ti-15Mo alloy was prepared by PM. Gas atomized powder was sintered by spark plasma sintering (SPS) above the β-transus temperature of the studied alloy. The compaction of the powders was accomplished by short-time sintering. The effect of the time of sintering on the porosity and the microhardness in centre part as well as in periphery part of the sample was investigated. The samples revealed significant inhomogeneity the porosity increases with the distance from the centre of the specimen. With increasing sintering times the porosity decreases and simultaneously the microhardness increases. Klíčová slova: Metastable β-titanium alloys; Porosity; Powder metallurgy; Spark plasma sintering Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
The effect of spark plasma sintering on the porosity and mechanical properties of Ti-15Mo alloy

Metastable β-titanium alloys are receiving much interest for various applications such as aircraft industry and medicine thanks to their excellent mechanical properties and biocompatibility. The ...

Terynková, A.; Kozlík, J.; Bartha, K.; Chráska, Tomáš; Dlabáček, Zdeněk; Stráský, J.
Ústav fyziky plazmatu, 2018

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