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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 ...
Ceramic protection of anti-corrosion layers of 3-glycidyloxypropyl-triethoxysilane on steel
Pokorný, P.; 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:
ceramic protection; 3-glycidyloxypropyl-triethoxysilane; steel
Fulltext is available at external website.
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 ...
Composite coatings containing nanometric constituents prepared by plasma spraying with liquid feedstocks
Mušálek, Radek; Tesař, Tomáš; Medřický, Jan; Čížek, Jan; Lukáč, František
2021 - English
Plasma spraying of liquid feedstocks allows deposition of materials with novel microstructures. Due to the combination of a liquid carrier and ultrafine powders (in case of suspensions) or in-situ formation of the final material in the plasma jet (in case of solutions), preparation of ultrafine composites is possible, typically in a form of coatings on the substrates. Moreover, both suspension and solution spraying routes can be easily combined, either together or even with conventional plasma spraying of coarse dry powders, thus merging benefits of “nanometric” and “micrometric” constituents in the final composite microstructure. As a consequence, liquid feedstock plasma spraying represents an industrially-relevant deposition process with wide variability, providing coatings with properties tailored for various applications ranging from compact wear-resistant layers, porous thermal barrier coatings, bio-compatible medical coatings, catalyst carriers, fuel-cells, etc. The paper introduces several examples of such ultrafine coatings recently deposited at IPP CAS using hybrid water-stabilized plasma torch.
Keywords:
Coatings; Functionally graded materials (FGMs); Liquid feedstock; Plasma spraying
Fulltext is available at external website.
Composite coatings containing nanometric constituents prepared by plasma spraying with liquid feedstocks
Plasma spraying of liquid feedstocks allows deposition of materials with novel microstructures. Due to the combination of a liquid carrier and ultrafine powders (in case of suspensions) or in-situ ...
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 ...
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 ...
Tungsten-steel and tungsten-chromium composites prepared by RF plasma spraying
Matějíček, Jiří; Klečka, Jakub; Čížek, Jan; Veverka, Jakub; Vilémová, Monika; Chráska, Tomáš; Ganesh, V.
2020 - English
For future fusion reactors, materials able to withstand harsh environments are needed. In particular, this concerns the plasma-facing components which are foreseen to consist of tungsten based plasma-facing armor and structural and cooling part made of steel. Currently, joining of these materials presents a significant challenge. The stress concentration at their interface, which arises due to thermal exposure and the difference in thermal and mechanical properties, can be reduced by composite/graded interlayers. Plasma spraying is among the prospective technologies for their preparation. In this work, tungsten-steel and tungsten-chromium composites were prepared by radio-frequency inductively coupled plasma (RF-ICP) spraying. Initial optimization of the spraying process for pure materials as well as their mixtures was carried out. Basic characterization of the layers for their structure, porosity and composition is presented.
Keywords:
tungsten; composites; RF plasma spraying
Fulltext is available at external website.
Tungsten-steel and tungsten-chromium composites prepared by RF plasma spraying
For future fusion reactors, materials able to withstand harsh environments are needed. In particular, this concerns the plasma-facing components which are foreseen to consist of tungsten based ...
Design of experimental device for testing of subcooled flow boilling
Gleitz, M.; Zacha, P.; Entler, Slavomír; Syblík, J.
2020 - English
The article presents the principle and function of the Hypervapotron and the current work progress on the realisation of the experimental loop. Hypervapotron is a heat exchanger operating in a two-phase flow regime, in which the latent heat of the water/steam phase transformation is used, which enables the transfer of large heat fluxes (up to tens of MW/m(2)). For this reason, it appears to be very promising for use in fusion reactors. The article describes the steps leading to the final design of the experimental loop selection of suitable mesh parameters in the Star-CCM+ code, geometry and used materials of the single elements of the heating system using electromagnetic induction. The effort of the experimental loop and the flow study in the Hypervapotron in general, is dimensional and material optimization of the geometry is suitable for a wide range of applications for which the benefits of subcooled boiling and Hypervapotron geometry can be applied.
Keywords:
Hypervapotron; Star-CCM; Fusion; Subcooled boiling; Induction heating
Fulltext is available at external website.
Design of experimental device for testing of subcooled flow boilling
The article presents the principle and function of the Hypervapotron and the current work progress on the realisation of the experimental loop. Hypervapotron is a heat exchanger operating in a ...
High temperature corrosion studies of HVOF sprayed coatings in molten sulphate salts environment
Lencová, K.; Česánek, Z.; Houdková, Š.; Lukáč, František; Mušálek, Radek
2019 - English
The generally applied requirements on lowering of emission production in the field of power industry have led, among others, into the application of low-emission combustion process of coal fired power plants. Besides the emissions reduction, this process has led to an increase of boilers parts corrosion degradation due to the reducing atmosphere in low-emission boilers, responsible for sulphide corrosion and molten salt attack. In such environment, the protection of the exposed surfaces gains importance. Among others, the thermal spraying technology can offer a suitable way of surface corrosion protection. In the present work, the high temperature corrosion behaviour of CoCrAlYTaCSi and Cr3C2-25%NiCr High Pressure/High Velocity Oxygen Fuel (HP/HVOF) sprayed coatings is evaluated and compared to the behaviour of bare structural steel (SPT360) substrate. The specimens were exposed to a molten salt environment, i. e., 12% Na2SO4 + 82% Fe2(SO4)3 at 690 °C under cyclic condition, simulating the working environment in low-emission boilers of coal-fired power plants. The thermogravimetric method was used to establish the kinetics of corrosion. 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 thermogravimetric measurement shows high oxidation rate of SPT360 steel. Cr3C2-25%NiCr coating provides slightly better performance compared to CoCrAlYTaCSi coating. Based on the obtained results, both coatings were found to have higher corrosion resistance than the SPT360 steel substrate, offering a sufficient surface protection in a given environment.
Keywords:
Coal fired boilers; CoCrAlYTaCSi; Cr3C2-25%NiCr; High temperature corrosion; hvof; Low-emission boilers; Thermal spraying
Fulltext is available at external website.
High temperature corrosion studies of HVOF sprayed coatings in molten sulphate salts environment
The generally applied requirements on lowering of emission production in the field of power industry have led, among others, into the application of low-emission combustion process of coal fired power ...
Technical manual - collimator
Kredba, Jan; Steiger, Lukáš; Tomka, David; Václavík, Jan
2018 - English
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].
Keywords:
collimator; NEOSTED; TOPTEC; optical testing; interferometry
Available at various institutes of the ASCR
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 ...
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