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Microstructure of commercially pure titanium after cryogenic milling and spark Plasma sintering
Kozlík, J.; Harcuba, P.; Stráský, J.; Chráska, Tomáš; Janeček, M.
2018 - English
Commercially pure titanium was prepared by advanced powder metallurgy methods with the aim to produce the ultra-fine grained material. Cryogenic attritor milling was used as a first step to refine the microstructure at liquid argon temperatures to suppress recovery and dynamic recrystallization. Spark plasma sintering was subsequently employed to produce bulk material, exploiting its ability to achieve fully dense structure in short time and thus to reduce the grain growth. In order to understand the undergoing microstructural changes during the process, detailed investigation was performed after each preparation step. Powder morphology was changed significantly after milling, while particle fragmentation was only limited. Grain size after sintering was in micrometer scale, relatively independent of sintering conditions.
Keywords:
Cryogenic milling; Microstructure; Spark plasma sintering; Titanium
Available at various institutes of the ASCR
Microstructure of commercially pure titanium after cryogenic milling and spark Plasma sintering
Commercially pure titanium was prepared by advanced powder metallurgy methods with the aim to produce the ultra-fine grained material. Cryogenic attritor milling was used as a first step to refine the ...
Thin nitride layers as permeation barriers
Veverka, Jakub; Matějíček, Jiří; Lukáč, František; Pospíšil, D.; Cvrček, L.; Nemanič, V.
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
Thin nitride layers as permeation barriers
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 ...
Characterization of flame sprayed abradable seal NiCrAl-bentonite coatings
Houdková, Š.; Česánek, Z.; Schubert, J.; Lukáč, František; Bystrianský, M.
2018 - English
The NiCrAl-21% Bentonite abradable coating, deposited by flame spraying, was exposed to 720°C / 1 hour air-annealing to evaluate its resistance against heat-induced changes. The SEM and XRD microstructure evaluation was done. After the air-annealing, the increase of HR15Y surface hardness was recorded and accompanied with decrease of abradability evaluated by Progressive Readability Hardness (PAH) test, although no demonstrable microstructural changes was recorded by SEM. XRD analyses evidenced the formation of nickel oxides and ordered Ni3Al phase during the air-annealing. Besides the abradable coating evaluation, this work brings the verification of the potential of PAH for scratch hardness testing. The measurement provides the results with low scatter, compared to usual surface hardness testing, and enables to distinguish between the depth of indentation in loaded and unloaded state, pointing out to the elastic/plastic deformation ratio.
Keywords:
Abradability; Abradable seal; Flame spray; NiCrAl-Bentonite
Available at various institutes of the ASCR
Characterization of flame sprayed abradable seal NiCrAl-bentonite coatings
The NiCrAl-21% Bentonite abradable coating, deposited by flame spraying, was exposed to 720°C / 1 hour air-annealing to evaluate its resistance against heat-induced changes. The SEM and XRD ...
Transport and package manual - collimator
Steiger, Lukáš; Václavík, Jan
2018 - English
The purpose of this document is to provide basic set of instructions and recommendations that allows careful transportation 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]
Keywords:
collimator; handling; TOPTEC
Available at various institutes of the ASCR
Transport and package manual - collimator
The purpose of this document is to provide basic set of instructions and recommendations that allows careful transportation of the NEOSTED collimator (COL).\nBe aware that it is not purpose of this ...
Study on polishing of CaF2 plane-parallel elements
Procháska, František; Thoř, Tomáš; Šípová, Gabriela
2018 - English
Determination of technological procedure for processing of plane-parallel and plano-convex CaF2 optical elements. That includes optical polishing as well as preparation of samples for polishing, i.e. cementing and grinding.
Keywords:
CaF2 machining
Available at various institutes of the ASCR
Study on polishing of CaF2 plane-parallel elements
Determination of technological procedure for processing of plane-parallel and plano-convex CaF2 optical elements. That includes optical polishing as well as preparation of samples for polishing, i.e. ...
Study on polishing of ZnSe with diamond suspension
Procháska, František; Thoř, Tomáš
2018 - English
Observe the effect of diamond slurries as polishing element on ZnSe, i.e. observe the change of surface of ZnSe as consequence to the series of polishing with the use of mentioned diamond slurries.
Keywords:
ZnSe polishing; Diamond polishing slurry
Available at various institutes of the ASCR
Study on polishing of ZnSe with diamond suspension
Observe the effect of diamond slurries as polishing element on ZnSe, i.e. observe the change of surface of ZnSe as consequence to the series of polishing with the use of mentioned diamond slurries.
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 ...
Feedhorn Coating - research report
Václavík, Jan
2017 - English
The report contains a description of the developed methods for metalizing of prototype of the FEEDHORN demonstrator, which is made up of a specially shaped carbon fiber composite carrier and a CNT layer. The report contains the results and comments for future construction of similar types of devices.
Keywords:
cnt layer; metalization; vacuum evaporation
Available at various institutes of the ASCR
Feedhorn Coating - research report
The report contains a description of the developed methods for metalizing of prototype of the FEEDHORN demonstrator, which is made up of a specially shaped carbon fiber composite carrier and a CNT ...
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 ...
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 ...
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