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Enthalpy Probe Diagnostics of Steam/Argon Plasma Jet
Hlína, Michal; Hrabovský, Milan
2015 - anglický
DC plasma torch with argon/water stabilization features extreme properties of the exiting plasma jet. The plasma mass flow rate is very low while the temperature reaches very high values. Plasma properties were measured by enthalpy probe connected to a mass spectrometer. The measurements of enthalpy, temperature, density and dynamic pressure were carried out for three different arc currents and at atmospheric pressure. The dependences of plasma characteristics on arc current were shown.
Klíčová slova:
enthalpy probe; thermal plasma; plasma diagnostics
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Enthalpy Probe Diagnostics of Steam/Argon Plasma Jet
DC plasma torch with argon/water stabilization features extreme properties of the exiting plasma jet. The plasma mass flow rate is very low while the temperature reaches very high values. Plasma ...
Boronized stainless steel with zirconia coatings
Brožek, Vlastimil; Kolísko, J.; Kubatík, Tomáš František; Mastný, L.; Pokorný, P.; Tej, P.
2015 - anglický
Conditions of boronizing are described using a reactive diffusion method of boron from boron carbide and lanthanum hexaboride so that the formation of Fe2B is preferred to FeB which is more brittle and whose structure does not satisfy the conditions for perfect adhesion of modified zirconia ceramics. Perfectly rigid adhesive connection of needle-like embedded interlayers Fe2B in steel AISI 303 prepared by reactive diffusion of a boronizing medium without activators at 1000 ° C and exposure of 2-4 hours has the value of 20 - 24 MPa at the Pinn-off test.Ceramic coatings from Al2O3-ZrO2 ceramics formed on those interlayers have the value of bond strength up to 14 - 20 MPa.Thermal cycling between 100°C - 600 °C confirmed good adhesion of coatings with the underlying steel.During thermal cycling at elevated temperatures (600-1000 °C) there occurs a statistically significant number of faults in cohesion and mechanical destruction of the coatings. One of the reasons are secondary changes
Klíčová slova:
Boronised steel; plasma spraying; ceramic coatings; bond strength; zirkonia coatings
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Boronized stainless steel with zirconia coatings
Conditions of boronizing are described using a reactive diffusion method of boron from boron carbide and lanthanum hexaboride so that the formation of Fe2B is preferred to FeB which is more brittle ...
Radial propagation of L-mode structures in COMPASS tokamak
Kovařík, Karel; Ďuran, Ivan; Stöckel, Jan; Seidl, Jakub; Havlíček, Josef; Háček, Pavel; Spolaore, M.; Vianello, N.
2015 - anglický
Various structures appear in the tokamak scrape-off layer (SOL) plasma with effects on plasma behavior. The filamentary probe recently introduced in the COMPASS tokamak allows measurement of electrostatic and magnetic properties of the filaments and their changes in dependence on distance from the last closed flux surface. This work presents evolution of the measured electromagnetic properties and their radial profiles as a part of the complex study of the processes in the SOL.
Klíčová slova:
plasma; tokamak
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Radial propagation of L-mode structures in COMPASS tokamak
Various structures appear in the tokamak scrape-off layer (SOL) plasma with effects on plasma behavior. The filamentary probe recently introduced in the COMPASS tokamak allows measurement of ...
Microstructure and Properties of Spark Plasma Sintered Al-Zn-Mg-Cu Alloy.
Zyka, J.; Málek, J.; Pala, Zdeněk; Andršová, I.; Veselý, J.
2015 - anglický
High entropy alloys are a new material class with promising structural and mechanical properties in wide range of applications. In principle they consist of five or more elements in equimolar concentrations resulting basically in single phase microstructure. TaNbHfZrTi alloy was developed by Senkov for high temperature applications.\nSince all of these elements are biocompatible the TaNbHfZrTi alloy can be investigated as a prospective bio implant material. The alloy was prepared by vacuum arc melting, no annealing treatment was applied. Tensile test and hardness test at room temperature were performed with very good results: yield strength 1155 MPa, rupture strength 1212 MPa, Vickers hardness 359 HV30. Microstructure and fracture morphology was also investigated.
Klíčová slova:
High Entropy Alloys; Microstructure; Mechanical Properties; Tensile Test
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Microstructure and Properties of Spark Plasma Sintered Al-Zn-Mg-Cu Alloy.
High entropy alloys are a new material class with promising structural and mechanical properties in wide range of applications. In principle they consist of five or more elements in equimolar ...
Preliminary Measurements of Neutrons From The D-D Reaction in The Compass Tokamak
Dankowski, J.; Janky, Filip; Kurowski, A.; Stöckel, Jan; Twarog, D.
2014 - anglický
Recent results of measured fast neutrons created in the D-D reaction on the COMPASS tokamak during ohmic discharges are presented in this paper. Two different type detectors were used during experiment. He-3 detectors and bubble detectors as a support. The measurements are an introduction for neutron diagnostic on tokamak COMPASS and monitoring neutrons during discharges with Neutral Beam Injection (NBI). The He-3 counters and bubble detectors were located in two positions near tokamak vacuum chamber at a distance less than 40 cm to the centre of plasma. The neutrons flux was observed in ohmic discharges. However, analysis of our results does not indicate any clear source of neutrons production during ohmic discharges.
Klíčová slova:
fusion; tokamak; neutrons; plasma diagnostics; COMPASS; bubble detectors
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Preliminary Measurements of Neutrons From The D-D Reaction in The Compass Tokamak
Recent results of measured fast neutrons created in the D-D reaction on the COMPASS tokamak during ohmic discharges are presented in this paper. Two different type detectors were used during ...
Poisson Equation Solver Parallelisation for Particle-in-Cell Model
Podolník, Aleš; Komm, Michael; Dejarnac, Renaud; Gunn, J. P.
2014 - anglický
Numerical simulations based on PIC technique like the SPICE2 model developed at IPP ASCR are often used in tokamak plasma physics to investigate the interaction of edge plasma with plasma-facing components. The SPICE2 model has been parallelised with the exception of the Poisson equation solver which considerably slows down the simulations. It is now being upgraded to a parallelised version to be efficient enough to perform more demanding tasks like the ITER tokamak baseline scenario edge plasma whose conditions like high density (up to 1020 m−3) and low temperature (1–2 eV) result in simulations taking several months to compute. Performance and scaling are compared for different cases in order to choose the optimal candidate for aforementioned applications.
Klíčová slova:
plasma; tokamak; ITER
Dokument je dostupný na externích webových stránkách.
Poisson Equation Solver Parallelisation for Particle-in-Cell Model
Numerical simulations based on PIC technique like the SPICE2 model developed at IPP ASCR are often used in tokamak plasma physics to investigate the interaction of edge plasma with plasma-facing ...
Influence of isothermal exposure on microstructural changes resulting in delamination of eutectic Al2O3+ZrO2+SiO2 thermal barrier coatings
Jech, D.; Čelko, L.; Chráska, Tomáš; Slámečka, K.; Klakurková, L.; Dubský, Jiří; Švejcar, J.
2014 - anglický
Eutectic ceramic Al2O3-ZrO2-SiO2 also termed Eucor (as a top coat) and CoNiCrAlY (as a bond coat) coatings were sprayed onto the surface of recently developed fine-grained cast polycrystalline nickel-based superalloy Inconel 713 LC by means of water stabilized plasma (WSP) and atmospheric plasma spraying (APS) techniques, respectively.Specimens were subjected to isothermal oxidation at 1050 °C for 10, 50, 100, 200 and 500 hours in ambient atmosphere,prior to which a half of the as-sprayed specimens was annealed at the temperature of 950 °C for 10 hours.Influence of short-time and long-time isothermal exposure on interactions at the bond-coat/top-coat interface was studied.The uniform and continuous oxide layer,also termed the thermally grown oxide (TGO),was formed and grew at the bond-coat/top-coat interface in all samples, both with and without the heat pre-treatment. Relationship between the dwell time, heat treatment and TGO growth kinetics was quantified.Microstructural changes
Klíčová slova:
Electron microscopy-scanning; Heat treatment; Image analysis; Thermal barrier coatings; Thermal plasma spraying
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Influence of isothermal exposure on microstructural changes resulting in delamination of eutectic Al2O3+ZrO2+SiO2 thermal barrier coatings
Eutectic ceramic Al2O3-ZrO2-SiO2 also termed Eucor (as a top coat) and CoNiCrAlY (as a bond coat) coatings were sprayed onto the surface of recently developed fine-grained cast polycrystalline ...
Thermal Coatings for Glass Industry
Chráska, Pavel; Neufuss, Karel
2014 - anglický
A new type of plasma torch with combined stabilization of electric arc by water vortex and gas flow is presented. This hybrid water/gas stabilization offers the possibility of adjusting plasma jet parameters within a wide range from high-enthalpy low-density plasmas typical for liquid stabilized torches to lower enthalpy higher density plasmas generated in gas stabilized torches. Moreover, gas flow in the cathode part protects a cathode tip and thus a consumable graphite cathode used in water-only stabilized plasma torches could be replaced by a fixed tungsten cathode. Examples of hybrid WSP torch utilization for high temperature application are given.
Klíčová slova:
glass melts; high temperature loading; glass forming tools; service life; coatings
Dokument je dostupný na externích webových stránkách.
Thermal Coatings for Glass Industry
A new type of plasma torch with combined stabilization of electric arc by water vortex and gas flow is presented. This hybrid water/gas stabilization offers the possibility of adjusting plasma jet ...
Composites of titanium carbide with scandium matrix
Brožek, Vlastimil; Pala, Zdeněk; Vilémová, Monika; Kubatík, Tomáš František; Mušálek, Radek; Nevrlá, Barbara; Mastný, L.
2014 - anglický
First reference about existence of ultrahard composite in the TiC-ScCx system was made by G.V. Samsonov in the year 1962. Further research performed on ICT Prague and University of Vienna proved a discrepancy in the structure and stoichiometry of scandium carbide. Analogously to cubic carbides and nitrides of 3rd period metals, Scandium was also expected to have extreme hardness, high chemical stability and to enable solid solution formation (Vegard rule) with controlled regulation of physical parameters. Higher hardness of the cubic carbides is related to the decrease of lattice parameter, thus is was expected that smaller atomic radius of Sc in TixSc1-xC solid solution will lead to increase in hardness. However it was discovered that scandium carbide differs chemically as well as structurally, e.g. Sc15C19 is hydrolyzed and the product of the reaction is hydrogen, allylen and other hydrocarbons. Due to high price of Sc compounds, CVD and PVD layers of TiAlN or TiScAlN on sintered
Klíčová slova:
hard compounds; titanium carbide; scandium oxycarbide; spark plasma sintering
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Composites of titanium carbide with scandium matrix
First reference about existence of ultrahard composite in the TiC-ScCx system was made by G.V. Samsonov in the year 1962. Further research performed on ICT Prague and University of Vienna proved a ...
Selective Leaching as a Method of Metallic Nanoparticles Preparation
Michalcová, A.; Vojtěch, D.; Kubatík, Tomáš František; Marek, I.; Svobodová, P.; Novák, P.
2014 - anglický
Selective leaching is process used mainly in analytical praxis–alloy matrix is dissolved and the residuum can be study by different methods. In this article, modification of selective leaching determined for production of metallic nanoparticles is described.Selective leaching technique lays in preparation of supersaturated solid solution of desired element in matrix metal –by convenient heat treatment or by rapid solidification of the binary alloy. Consequently, the matrix metal is selectively dissolved and metal nanoparticles from other metal are formed. The size, shape and agglomeration of forming metallic nanoparticles are dependent on many factors such as reaction temperature, concentration of leaching solution, additives present in leaching solution. The metal mainly used as matrix component is aluminium due to is amphoteric behaviour. It enables aluminium dissolution in sodium hydroxide without affecting the minor metal. Nobel metals like silver or copper forms
Klíčová slova:
Nanocrystaline materials; selective leaching
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Selective Leaching as a Method of Metallic Nanoparticles Preparation
Selective leaching is process used mainly in analytical praxis–alloy matrix is dissolved and the residuum can be study by different methods. In this article, modification of selective leaching ...
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