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Synergic effects of laser – TIG welding
Kubíček, J.; Doležal, P.; Mrňa, Libor; Šebestová, Hana; Horník, Petr
2018 - Czech
Laser welding compared to conventional arc methods is accompanied by rapid cooling rates. It can lead to the formation of undesirable microstructure of the weld metal and heat affected zone of some steel grades which has a negative impact on their mechanical properties. The preheating is quite problematic because of high speed of laser welding. The possibility of preheating by the heat of the arc discharge of the associated TIG burner has been tested. Precise holder has been fabricated to fix the burner to the laser welding head allowing TIG electrode positioning towards the laser beam and the workpiece. A number of high strength steel S460MC and S700MC welding experiments was performed. The effect of TIG current on microstructural changes has been proven. Some welding experiments were compared to the SYSWELD welding simulations.\n Laserové svařování ve srovnání s konvenčními obloukovými metodami je doprovázeno rychlou rychlostí chlazení. To může vést ke vzniku nežádoucí mikrostruktury svařovaného kovu a tepelně postižené zóny některých ocelových tříd, což má negativní dopad na jejich mechanické vlastnosti. Předehřívání je poměrně problematické kvůli vysoké rychlosti svařování laserem. Byla testována možnost předehřívání teplem z obloukového výboje přidruženého hořáku TIG. Přesný držák byl vyroben pro upevnění hořáku na laserovou svařovací hlavu, umožňující umístění TIG elektrody směrem k laserovému paprsku a obrobku. Byla provedena řada ocelových zkoušek S460MC a S700MC s vysokou pevností. Účinek proudění TIG na mikrostrukturální změny byl prokázán. Některé svařovací experimenty byly porovnány s simulacemi svařování SYSWELD.
Keywords:
laser – TIG welding; cooling rate; HSLA steels; microstructure; tensile strength
Available at various institutes of the ASCR
Synergic effects of laser – TIG welding
Laser welding compared to conventional arc methods is accompanied by rapid cooling rates. It can lead to the formation of undesirable microstructure of the weld metal and heat affected zone of some ...
Recent Trends in Charged Particle Optics and Surface Physics Instrumentation. Proceedings of the 16th International Seminar
Mika, Filip; Pokorná, Zuzana
2018 - English
The origins of the seminar “Recent Trends in Charged Particle Optics and Surface Physics Instrumentation” date back into the eighties, when as a part of the isolated “Eastern Bloc”, we were short of English-language books, papers and conferences. In 1990, at the second Seminar, there were as many as 30 participants from 5 countries. The third Seminar in 1992 was moved to hotel Skalský dvur in the Bohemian-Moravian Highlands where it has been held as a biannual meeting ever since.\nThe Seminar takes place in a secluded lakeside hotel surrounded by beautiful nature and calm forests, so all participants have a great possibility to see each other every day and to discuss their topics of interest in more detail. This is a great advantage compared to the huge bustling conferences with their many parallel sections, which are a lively celebration of science but\nsometimes it is difficult to meet there the person with whom you want to discuss a particular scientific topic in more detail.\nFrom the very beginning, the Seminar has been conceived as a meeting devoted more to asking questions not answered yet, than to reporting results. This spirit is usually less present in the introductory presentations and posters but is dominant in the following discussions.\n
Keywords:
charged particle optics; surface physics; instrumentation
Available at various institutes of the ASCR
Recent Trends in Charged Particle Optics and Surface Physics Instrumentation. Proceedings of the 16th International Seminar
The origins of the seminar “Recent Trends in Charged Particle Optics and Surface Physics Instrumentation” date back into the eighties, when as a part of the isolated “Eastern Bloc”, we were short of ...
Very low energy electron transmission spectromicroscopy
Daniel, Benjamin; Radlička, Tomáš; Piňos, Jakub; Mikmeková, Šárka; Konvalina, Ivo; Frank, Luděk; Müllerová, Ilona
2018 - English
For more than 25 years, Scanning Low Energy Electron Microscopy (SLEEM) has been\ndeveloped at the Institute of Scientific Instruments (ISI), with several commercially available SEMs adapted with a cathode lens for SLEEM use, as well as a dedicated self-built UHVSLEEM setup.\nFor a better understanding of contrast formation at low energies, especially at very low energies below 50 eV, where the local density of states plays an important role, more general knowledge about the interaction of (very) low energy electrons with solids is required. This will be achieved using a newly developed ultra-high vacuum (UHV SLEEM) setup which includes several enhancements compared to other available machines. Data processing is presented in, and processed data will be further used and tested with the Monte Carlosimulation package BRUCE, which is being developed by Werner et al. at TU Vienna.
Keywords:
low energy scanning electron microscopy; electron microscopy; time of flight; electron energy lost spectroscopy
Available at various institutes of the ASCR
Very low energy electron transmission spectromicroscopy
For more than 25 years, Scanning Low Energy Electron Microscopy (SLEEM) has been\ndeveloped at the Institute of Scientific Instruments (ISI), with several commercially available SEMs adapted with a ...
Hiding e-beam exposure fields by deterministic 2D pattering
Horáček, Miroslav; Knápek, Alexandr; Matějka, Milan; Krátký, Stanislav; Urbánek, M.; Mika, Filip; Kolařík, Vladimír
2018 - English
The high stability and good current homogeneity in the spot of the e-beam writer is crucial to\nthe exposure quality, particularly in the case of large-area structures when gray-scale\nlithography is used. Even though the deflection field distortion is calibrated regularly and\nbeam focus and beam astigmatism is dynamically corrected over the entire deflection field, we can observe disturbances in the exposed relief.\nRecently, we presented a method that makes use of e–beam exposure imperfection by\nintroducing marginally visible high–frequency diffraction gratings of variable pitch that fill in\nseparate orthogonal exposure fields. The actually presented approach follows up our\nresearch on aperiodic arrangements of optical primitives, especially on the phyllotactic–\nlike arrangement of sub–micron relief optical elements. This approach is extended from the\ndiffraction element arrangement to the higher level of exposure fields arrangements.
Keywords:
phyllotaxis; electron beam lithography
Available at various institutes of the ASCR
Hiding e-beam exposure fields by deterministic 2D pattering
The high stability and good current homogeneity in the spot of the e-beam writer is crucial to\nthe exposure quality, particularly in the case of large-area structures when gray-scale\nlithography is ...
STEM modes in SEM
Konvalina, Ivo; Paták, Aleš; Mikmeková, Eliška; Mika, Filip; Müllerová, Ilona
2018 - English
The segmented semiconductor STEM detector in the Magellan 400 FEG SEM microscope\n(https://www.fei.com/) is used to detect transmitted electrons (TEs) and allows observing\nsamples in four imaging modes. Two modes of objective lens, namely high resolution (HR)\nand ultra-high resolution (UHR), differ by their resolution and by the presence or absence of\na magnetic field around the sample. If the beam deceleration (BD) mode is chosen, then\nan electrostatic field around the sample is added and two further microscope modes HR + BD\nand UHR + BD, become available. Trajectories of TEs are studied with regard to their angular\nand energy distribution in each mode in this work.\n
Keywords:
SEM; STEM
Available at various institutes of the ASCR
STEM modes in SEM
The segmented semiconductor STEM detector in the Magellan 400 FEG SEM microscope\n(https://www.fei.com/) is used to detect transmitted electrons (TEs) and allows observing\nsamples in four imaging ...
Creation of electron vortex beams using the holographic reconstruction method in a scanning electron microscope
Řiháček, Tomáš; Horák, M.; Schachinger, T.; Matějka, Milan; Mika, Filip; Müllerová, Ilona
2018 - English
Electron vortex beams (EVB) were theoretically predicted in 2007 and first experimentally\ncreated in 2010. Although they attracted attention of many researchers, their\ninvestigation takes place almost solely in connection with transmission electron microscopes (TEM). On the other hand, although scanning electron microscopes (SEM) may provide some advantages for EVB applications, only little attention has been dedicated to them. Therefore, the aim of this work is to create electron vortices in SEM at energies of several keV.
Keywords:
electron vortex beams; scanning electron microscopy; electron diffraction
Available at various institutes of the ASCR
Creation of electron vortex beams using the holographic reconstruction method in a scanning electron microscope
Electron vortex beams (EVB) were theoretically predicted in 2007 and first experimentally\ncreated in 2010. Although they attracted attention of many researchers, their\ninvestigation takes place ...
Locking in on large volume light-sheet microscopy
Vettenburg, T.; Dalgarno, H.I.C.; Nylk, J.; Coll-Lladó, C.; Ferrier, D.E.K.; Čižmár, Tomáš; Gunn-Moore, F.J.; Dholakia, K.; Corral, A.; Rodriguez-Pulido, A.; Flors, C.; Ripoll, J.
2018 - English
Fluorescence light-sheet microscopy is increasingly adopted by developmental biologists to study how cells divide and differentiate to form organs and even entire organisms. The lightsheet microscope differs from a conventional microscope in that the specimen is illuminated by a plane of light orthogonal to the detection axis, thus keeping the out-of-focus areas dark while minimizing any potentially detrimental exposure of the sample. The light-sheet microscope has been found to be the ideal instrument for long-term and non-invasive studies of intact, and therefore three-dimensional, fluorescent samples.
Keywords:
cellular imaging; fluorescence imaging; light-sheet microscopy
Available at various institutes of the ASCR
Locking in on large volume light-sheet microscopy
Fluorescence light-sheet microscopy is increasingly adopted by developmental biologists to study how cells divide and differentiate to form organs and even entire organisms. The lightsheet microscope ...
SMV-2018-12: Development of welding and brazing joints for mechanical assemblies
Zobač, Martin; Vlček, Ivan; Dupák, Libor
2018 - Czech
The subject of the project was further research and development of permanent joints of metal materials by electron beam welding and development of procedures of temperature stabilisation of metal part. The outcome of the project were specific technological procedures for the given assemblies. The significant experimental demands were characteristic for this project. Předmětem řešeného projektu byl další výzkum a vývoj nerozebiratelných spojů kovových materiálů s využitím technologie svařování elektronovým svazkem a vývoj postupů teplotní stabilizace kovových dílů. Výsledkem projektu byly konkrétní technologické postupy pro konkrétní sestavy. Pro daný projekt byla charakteristická značná experimentální náročnost.
Keywords:
electron beam welding; vacuum brazing; temperature stabilisation
Available at various institutes of the ASCR
SMV-2018-12: Development of welding and brazing joints for mechanical assemblies
The subject of the project was further research and development of permanent joints of metal materials by electron beam welding and development of procedures of temperature stabilisation of metal ...
SMV-2018-13: Research and development of electron guns designed for welding
Zobač, Martin; Vlček, Ivan; Dupák, Libor
2018 - Czech
The subject of the project was further research and development of the electron gun for electron beam welding. The improvements were aimed to specific components from which are the electron guns assembled. A series of samples was produced for the product evaluation. Předmětem projektu bylo pokračování výzkumu a vývoje trysek pro elektronové svařování a příslušenství. Probíhající fáze byla zaměřena na úpravy dílčích součástí trysek. Pro otestování modifikací byly vyrobeny ověřovací vzorky.
Keywords:
electron gun; electron beam welding machine
Available at various institutes of the ASCR
SMV-2018-13: Research and development of electron guns designed for welding
The subject of the project was further research and development of the electron gun for electron beam welding. The improvements were aimed to specific components from which are the electron guns ...
SMV-2018-07: Design, development and experimental depostion of interference filter and mirror samples
Oulehla, Jindřich; Pokorný, Pavel
2018 - Czech
Development of various beam splitters/combiners and mirrors including antireflective coatings for 45° incidence and test sample deposition. Vývoj různých druhů beam splitterů/combinerů a zrcadel včetně antireflexních vrstev pro dopad světla 45° a depozice jejich funkčních vzorků.
Keywords:
thin film optics; interference filters; e-beam evaporation
Available at various institutes of the ASCR
SMV-2018-07: Design, development and experimental depostion of interference filter and mirror samples
Development of various beam splitters/combiners and mirrors including antireflective coatings for 45° incidence and test sample deposition.
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