No (543)
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543
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Ceramic protection of anti-corrosion layers of 3-glycidyloxypropyl-triethoxysilane on steel
Pokorný, P.; Prodanović, N.; Janata, Marek; Brožek, Vlastimil
2023 - English
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.
Keywords:
steel; concrete; ceramics
Available at various institutes of the ASCR
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 ...
Preparation of W-Cu composites by infiltration of w skeletons review
Matějíček, Jiří
2021 - English
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.
Keywords:
Composites; Copper; Molten copper infiltration; Tungsten
Available at various institutes of the ASCR
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 ...
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 - English
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.
Keywords:
Heavy oils; High temperature corrosion; NiCr; NiCr-based coating; NiCrMoNbTa; Twin Wire Arc Spray; Vanadium
Available at various institutes of the ASCR
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 ...
Methodology for the characterization of the laser rod shape by multi-wave interferometry
Matoušek, Ondřej; Kredba, Jan; Procháska, František
2020 - Czech
The developed methodology describes the method of the multi-wave interferometry with controlled phase changing and the way of its application for the characterization of laser rod, which allows measurement of the shape of the front surfaces, wedge, deformation of the passing wavefront and internal inhomogeneity in a single measuring cycle Vytvořená metodika popisuje metodu multi vlnové interferometrie s řízenou změnou fáze a způsob její aplikace pro charakterizaci laserových tyčí, která umožňuje měření tvaru čelních povrchů, klínu, deformace průchozí vlnoplochy a vnitřní nehomogenity v jediném měřícím cyklu.
Keywords:
Multi-wave interferometry
Available at various institutes of the ASCR
Methodology for the characterization of the laser rod shape by multi-wave interferometry
The developed methodology describes the method of the multi-wave interferometry with controlled phase changing and the way of its application for the characterization of laser rod, which allows ...
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 - English
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.
Keywords:
Microhardness; Microstructure; NiCrAlY; Plasma spraying; Spark plasma sintering
Available at various institutes of the ASCR
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 ...
A Wide-Angle Photographic Camera of James G. Baker With the Paraboloidal Mirror
Rail, Zdeněk; Melich, Zbyněk; Šrajer, Bohdan; Vápenka, David; Tomka, David; Thoř, Tomáš; Pintr, Pavel; Macner, David
2020 - Czech
A field of view of the paraboloidal mirror is small. Dominant aberration which limits its angular diameter is coma. Using correctors consisting lenses and aspherical plates star images of the mirror systems can be radically corrected. In this paper we present optical design of such photographic camera computed by James G. Baker. His device is composed of a paraboloidal mirror, a cemented dublet in front of focus and an aspherical plate placed in entrance parallel beam. Zorné pole paraboloidického zrcadla je malé. Dominantní vada, která omezuje jeho úhlový průměr, je koma. Pomocí systémů čoček a asférických desek je možné u zrcadlových systémů mimoosové obrazy hvězd opravit a zorná pole zvětšit. V této práci předkládáme návrh takové fotografické komory, spočtené Jamesem G. Bakerem. Jeho fotografický přístroj se skládá z paraboloidického zrcadla, tmeleného dubletu před ohniskem a z asférické korekční desky, umístěné ve vstupním paralelním svazku před soustavou.
Keywords:
paraboloidal mirror; lens corrector; cemented dublet; aspheric plate; optical aberrations
Available at various institutes of the ASCR
A Wide-Angle Photographic Camera of James G. Baker With the Paraboloidal Mirror
A field of view of the paraboloidal mirror is small. Dominant aberration which limits its angular diameter is coma. Using correctors consisting lenses and aspherical plates star images of the mirror ...
The Technology of Manufacture of a Positive Lens of Achromatic Dublet
Rail, Zdeněk; Melich, Zbyněk; Šrajer, Bohdan; Šípová, Gabriela; Ulrichová, Iva; Franců, Helena; Melich, Radek; Vápenka, David; Tomka, David; Thoř, Tomáš
2020 - Czech
This paper deals with manufacturing of a positive lens of achromatic dublet. Diameter of the dublet is 158 mm and its focal length about 2500 mm. The glass material of the former lens was inhomogeneous and the dublet provided bad images. This is why we decided to manufacture new lens. The process was made by means of former machines of our workshop. The telescope with this dublet is placed at the Observatory of Turnov and serves for public astronomical observation. Tento referát popisuje technologický postup výroby spojky achromatického dubletu o průměru 158 mm a ohniskové vzdálenosti 2500 mm. Sklo, ze kterého byla vyrobena původní spojka, bylo nehomogenní a dublet špatně zobrazoval. Z tohoto důvodu jsme se rozhodli vyrobit novou spojku. Její výroba byla provedena na původních strojích naší dílny. Dublet je umístěn v dalekohledu na turnovské hvězdárně a slouží k veřejnému pozorování oblohy.
Keywords:
achromatic dublet; aplanat; coma; pherochromatic aberration
Available at various institutes of the ASCR
The Technology of Manufacture of a Positive Lens of Achromatic Dublet
This paper deals with manufacturing of a positive lens of achromatic dublet. Diameter of the dublet is 158 mm and its focal length about 2500 mm. The glass material of the former lens was ...
Residual Aberrations of the Gajdušek Objective Lens of Diameter 200 mm and Focal Length 3480 mm of the Observatory in Hradec Králové
Rail, Zdeněk; Melich, Zbyněk; Šrajer, Bohdan; Vápenka, David; Tomka, David; Thoř, Tomáš; Macner, David
2020 - Czech
The achromatic dublet of diameter 200 mm and focal length 3480 mm was manufactured by Professor ing. Vilém Gajdušek in Ostrava in 1954. The telescope with this objective is placed at the Observatory and planetarium in Hradec Králové. The objective was restored in the Institute of Plasma Physics, v.v.i.-Centrum Toptec in Turnov. During the process lens was measured and data were used for evaluation of its residual aberrations. We present the results of the measurement in this paper. Achromatický dublet o průměru 200 mm a ohniskové vzdálenosti 3480 mm byl vyroben profesorem ing. Vilémem Gajduškem v Ostravě v roce 1954. Dalekohled s tímto objektivem je umístěn na Hvězdárně a planetáriu v Hradci Králové. Objektiv byl v roce 2018 restaurován v Ústavu fyziky plazmatu, v.v.i.-Centru Toptec v Turnově. Čočky byly přeměřeny a z naměřených hodnot jsme vyčíslili jeho zbytkové optické vady. Výsledky simulace přinášíme v této práci.
Keywords:
achromatic dublet; aplanat; coma; pherochromatic aberration
Available at various institutes of the ASCR
Residual Aberrations of the Gajdušek Objective Lens of Diameter 200 mm and Focal Length 3480 mm of the Observatory in Hradec Králové
The achromatic dublet of diameter 200 mm and focal length 3480 mm was manufactured by Professor ing. Vilém Gajdušek in Ostrava in 1954. The telescope with this objective is placed at the Observatory ...
The Digitalisation of the Maksutov Camera 350/840 of the Observatory in Úpice
Rail, Zdeněk; Melich, Zbyněk
2019 - Czech
The Maksutov chamber with a diameter of 350 mm and a focal length of 840 mm was manufactured in Turnov in the early 1980s. At the Úpice Observatory it was used to photograph the sky for photographic film. Currently, we have been asked to convert it to a digital device. It was necessary to design and manufacture a correction element for the chamber to straighten its focal surface and to equip it with a suitable digital camera. In this work we present description of modification of this device. Maksutovova komora o průměru 350 mm a ohniskové vzdálenosti 840 mm byla vyrobena v Turnově počátkem 80. let. Na úpické observatoři sloužila k fotografování oblohy na fotografický film. V současné době jsme byli požádáni o jeji přestavbu na digitální přístroj. Pro komoru bylo nutné navrhnout a vyrobit korekční člen pro narovnání její ohniskové plochy a dále ji vybavit vhodným digitálním fotografickým přístrojem. V této práci přinášíme popis úpravy tohoto přístroje.
Keywords:
Maksutov chamber; focal surface
Available at various institutes of the ASCR
The Digitalisation of the Maksutov Camera 350/840 of the Observatory in Úpice
The Maksutov chamber with a diameter of 350 mm and a focal length of 840 mm was manufactured in Turnov in the early 1980s. At the Úpice Observatory it was used to photograph the sky for photographic ...
Suggested Changes After Prototype I Testing
Pintr, Pavel
2019 - Czech
Optical design description of rectangular spot of laser head. Our target was TOP HAT intensity distribution of rectangular spot for laser surfacing. Popis designu obdélníkového spotu laserové navařovací hlavice. Cílem bylo navrhnout TOP HAT obdélníkový spot vhodný pro laserové navařování.
Keywords:
laser welding; surfacing; infrared; rectantular spot; TOP HAT distribution
Available at various institutes of the ASCR
Suggested Changes After Prototype I Testing
Optical design description of rectangular spot of laser head. Our target was TOP HAT intensity distribution of rectangular spot for laser surfacing.
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