No (1013)
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1017
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Analysis of the surface layer of the brake disk
Švábenská, Eva; Roupcová, Pavla; Podstranská, Ivana; Petr, M.; Filip, J.; Schneeweiss, Oldřich
2015 - English
Our research is focused on the changes in thin surface layer of the brake disk due to the impact of severe plastic deformation and heating by friction process. The aim of this study is to compare structure, chemical and phase compositions of the surface layer in depth up to several hundreds of nanometers in the no affected central part of brake disk and the part which was in contact with brake pads by braking. The basic information on structure and phase composition was obtained by optical and scanning electron microscopy, X-Ray Powder Diffraction and Mössbauer Spectroscopy. The thin surface layer was studied using Conversion Electron Mössbauer Spectroscopy and X-ray Photoelectron Spectroscopy. We explain the observed changes with the knowledge on effects of plastic deformation and/or diffusion of alloying elements in the material of the brake disk.
Keywords:
grey cast iron; brake disk; microstructure analysis; surface layer
Available at various institutes of the ASCR
Analysis of the surface layer of the brake disk
Our research is focused on the changes in thin surface layer of the brake disk due to the impact of severe plastic deformation and heating by friction process. The aim of this study is to compare ...
THE EFFECTS OF HIGH TEMPERATURE HELIUM GAS ON THE FRACTURE BEHAVIOUR OF ODS MA957
Rozumová, L.; Hojná, A.; Kalivodová, J.; Bublíková, P.; Hadraba, Hynek; Di Gabriele, F.
2015 - English
Oxide-dispersion-strengthened steel (ODS) MA957 has been studied as a candidate material for Tritium Breeding Blanket for fusion reactors with helium coolant, where temperatures 250-650 degrees C are expected. Helium is one of type as primary coolant in High Temperature Reactor and Gas Cooled Fast Reactor with working temperature 500-1000 degrees C. \n\nThis work presents results of the study of behaviour of ODS (MA957) under influence of high temperature helium environment. Microstructure of the material and the interaction with He was investigated. The average exposure temperature was held at 720 degrees C. Subsequently, the surface changes were determined. Impact testing and material surfaces were studied in detail by means of SEM and TEM microscopy. It is essential to understand the He effect on microstructure and mechanical properties of structural materials since the He embrittlement in TBB may be significant.
Keywords:
ODS; MA957; Helium
Available at various institutes of the ASCR
THE EFFECTS OF HIGH TEMPERATURE HELIUM GAS ON THE FRACTURE BEHAVIOUR OF ODS MA957
Oxide-dispersion-strengthened steel (ODS) MA957 has been studied as a candidate material for Tritium Breeding Blanket for fusion reactors with helium coolant, where temperatures 250-650 degrees C are ...
THE INFLUENCE OF CONSOLIDATION PROCEDURE PARAMETERS ON COMPACTION OF AL POWDER
Lowe, T. C.; Kunčická, L.; Kocich, R.; Davis, C. F.; Hlaváč, L.; Dvořák, Jiří
2015 - English
The influence of different consolidation procedures on compaction of Al powders was evaluated. Powder preparation procedures consisted of selection of particle size distribution, cold isostatic pressing (CIP), and vacuum sintering. Processing parameters investigated included the number of compression steps, compression pressure, and sintering temperature and time. Densities of the samples after compression and also after sintering were measured and compared. The overall oxygen content was analysed using by Energy Dispersive Spectroscopy. Phase composition was determined using X-ray. Microhardness measurements were performed to evaluate the degree of compaction. Double-step CIP at 200+300 MPa and subsequent sintering at 500°C for 60 min produced the best combination of properties from all the consolidation technologies of Al particles. Of the particle size ranges studies, those with diameters between 20 and 45 μm produced the best results. Aluminum oxide was present in the structure after all the processing treatments.
Keywords:
Aluminum powder; cold isostatic pressing; sintering; oxygen content; X-ray
Available at various institutes of the ASCR
THE INFLUENCE OF CONSOLIDATION PROCEDURE PARAMETERS ON COMPACTION OF AL POWDER
The influence of different consolidation procedures on compaction of Al powders was evaluated. Powder preparation procedures consisted of selection of particle size distribution, cold isostatic ...
ATOMISTIC SIMULATIONS OF TWIN BOUNDARIES FACETING IN HCP MATERIALS
Ostapovets, Andriy
2015 - English
Deformation twinning is frequently observed in materials with hexagonal crystal lattice. It plays important role in plastic deformation of such materials. Twin regions have often lamellar shape and twin boundaries are usually oriented along invariant planes. However, non-invariant plane twin interfaces are also observed. Occurrence of such interfaces can be connected with interactions between twinning disconnections. Mechanisms of such interactions are discussed on the basis of atomistic simulations.
Keywords:
Twin boundaries; hcp; EAM potential
Available at various institutes of the ASCR
ATOMISTIC SIMULATIONS OF TWIN BOUNDARIES FACETING IN HCP MATERIALS
Deformation twinning is frequently observed in materials with hexagonal crystal lattice. It plays important role in plastic deformation of such materials. Twin regions have often lamellar shape and ...
MODIFIKOVANÁ ZKOUŠKA EXCENTRICKÝM TAHEM: VYHODNOCENÍ EXPERIMENTÁLNÍCH TESTŮ VÁLCOVÝCH TĚLES Z CEMENTOVÉHO KOMPOZITU
Holušová, T.; Lozano, M.; Komárková, T.; Kocáb, D.; Seitl, Stanislav
2015 - Czech
Modifikovaná zkouška excentrickým tahem (MCT) by mohla v budoucnu představovat stabilní zkoušku pro vyhodnocování lomově-mechanických parametrů nebo také únavového chování kompozitních materiálů jako je beton. Těleso pro MCT zkoušku s kruhovým průměrem může být snadno odebráno z jádrového vývrtu se zvolenou tloušťkou a velikostí průměru. Tato práce je zaměřena na vyhodnocení lomového chování MCT těles při statickém zatěžování a porovnání dvou různých uchycení do čelistí testovacího zařízení. Výsledky jsou prezentovány formou L-COD zatěžovacích digramů, tj. závislosti zatížení (L) měřeného v ose ocelových tyčí na velikosti otevření trhliny (COD). The modified compact tension test (MCT) might be in the future a stable test configuration for the evaluation of fracture-mechanics parameter or also a fatigue behavior of the composites materials such the concrete is. Core drilling can be employed to obtain specimens which are cylindrical in shape with the chosen thickness. This contribution focuses on the evaluation of MCT specimen fracture behavior during static tests and the comparison of two different fixing system of the test machine. The results are represented as L-COD diagrams (i.e. load vs. crack opening displacement measured on the loading axis.
Keywords:
Modified compact tension test; fracture parameters; composites; ARAMIS; L-COD
Available at various institutes of the ASCR
MODIFIKOVANÁ ZKOUŠKA EXCENTRICKÝM TAHEM: VYHODNOCENÍ EXPERIMENTÁLNÍCH TESTŮ VÁLCOVÝCH TĚLES Z CEMENTOVÉHO KOMPOZITU
Modifikovaná zkouška excentrickým tahem (MCT) by mohla v budoucnu představovat stabilní zkoušku pro vyhodnocování lomově-mechanických parametrů nebo také únavového chování kompozitních materiálů jako ...
Ab initio calculations of temperature dependent resistivity for transition metals
Wagenknecht, D.; Turek, Ilja; Carva, K.
2015 - English
The effect of phonons on electrical resistivity has been simulated by considering random displacements of atomic nuclei from their equilibrium positions together with a frozen-potential approach. The developed theory has been applied successfully to late transition metals (Fe, Ni, Rh, Pd, Pt).
Keywords:
electrical resistivity; temperature dependence; transition metals
Available at various institutes of the ASCR
Ab initio calculations of temperature dependent resistivity for transition metals
The effect of phonons on electrical resistivity has been simulated by considering random displacements of atomic nuclei from their equilibrium positions together with a frozen-potential approach. The ...
Effect of grit blasting surface treatment on high temperature low cycle fatigue life of Inconel 713LC
Šulák, Ivo; Obrtlík, Karel; Čelko, L.; Gejdoš, P.
2015 - English
This paper presents the results of high temperature low cycle fatigue tests carried out on Inconel 713LC. This polycrystalline nickel based superalloys is mainly used for high temperature applications such as disks, blades and vanes of gas turbine engines. These machine components are manufactured by investment casting and undergo a series of postcast processes to remove remnants of shells, oxides and other contaminants. Grit blasting is one of the most widely used and cheapest technology ensuring adequate cleaning of the surface and at the same time is used to treat the substrate surface prior to application of metalic bond coat and various protective coatings (like diffusion, overlay or thermall barier coatings). Low cycle fatigue tests were conducted on as-received and grit blasted material in fully reversed pull-push cycle in strain control mode with constant total strain amplitude and strain rate at 900 °C in air. Experimental data on fatigue life were evaluated and parameters of Baquin and Coffin-Manson curves were obtained for both tested materials. Specimen surface and cross sections of both treated and untreated materials were analysed prior to fatigue tests and also after testing by means of optical microscopy (OM), as well as scaning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and Vickers microhardness was measured. Fatigue degradation mechanisms was documented in both materials and negligible effect of grit blasting on low cycle parameters was discussed.
Keywords:
Grit blasting; Surface relief; Surface microhardnes; High temperature fatigue life; Inocel 713LC
Available at various institutes of the ASCR
Effect of grit blasting surface treatment on high temperature low cycle fatigue life of Inconel 713LC
This paper presents the results of high temperature low cycle fatigue tests carried out on Inconel 713LC. This polycrystalline nickel based superalloys is mainly used for high temperature ...
Analysis of nanoparticles released from the car brakes
Švábenská, Eva; Roupcová, Pavla; Schneeweiss, Oldřich
2015 - English
Our research is focused on the phase, structure and chemical analysis of the powder particles released by braking of cars from their brake components – discs and pads. The basic information on structure and phase composition was obtained by X-Ray Powder Diffraction, Mössbauer Spectroscopy and scanning electron microscopy with EDX. The results of the particle analysis are compared with materials used for manufacturing brake components and with the powder prepared by ball milling of the mixture of the pad composite and disk steel. Most of recognized nanoparticles are based on carbon, silica/silicates and iron oxides. Their effects on street environment are mentioned.
Keywords:
nanoparticles; wear debris; automotive brake
Available at various institutes of the ASCR
Analysis of nanoparticles released from the car brakes
Our research is focused on the phase, structure and chemical analysis of the powder particles released by braking of cars from their brake components – discs and pads. The basic information on ...
Thermo-mechanical and isothermal fatigue behavior of austenitic stainless steel AISI 316L
Škorík, Viktor; Šulák, Ivo; Obrtlík, Karel; Polák, Jaroslav
2015 - English
Many structural components of nuclear power plant systems are made of austenitic stainless steels. These structures undergo degradation by thermo-mechanical fatigue (TMF) caused by simultaneous cyclic straining and temperature cycling, particularly during start-up, shut-down and transient operations. The present work reports the cyclic deformation behavior and fatigue damage of austenitic stainless steel AISI 316L during TMF and isothermal fatigue (IF) testing in air. Total strain controlled in-phase TMF loading in the temperature range 200 - 600 °C and isothermal fatigue (IF) at 600 °C were performed. Hardening/softening curves, cyclic stress-strain response and fatigue life diagrams were obtained both for TMF and IF tests. Fatigue damage was documented using surface relief and fracture surface observations. Mean stress evolution and fatigue degradation data are employed to discuss the fatigue behavior of 316L steel both in TMF and IF regimes.
Keywords:
Thermo-mechanical fatigue (TMF); In-phase cycling (IP); Isothermal fatigue (IF); AISI 316L; Fatigue life
Available at various institutes of the ASCR
Thermo-mechanical and isothermal fatigue behavior of austenitic stainless steel AISI 316L
Many structural components of nuclear power plant systems are made of austenitic stainless steels. These structures undergo degradation by thermo-mechanical fatigue (TMF) caused by simultaneous cyclic ...
MAGNETIC AND TRANSPORT PROPERTIES OF 41CRMO4 STEEL
Bulín, T.; Hapla, Miroslav; Roupcová, Pavla; Ondrůšek, Č.; Schneeweiss, Oldřich
2015 - English
We have measured magnetic parameters and electrical resistivity of 41CrMo4 steel. It consist ferrite, Cr7C3 and Cr23C6 type of carbides. The\nmeasurements of temperature dependences of magnetic moments and electrical resistivity confirm phase stability of ferrite. The room temperature resistivity, saturation magnetization at room temperature, as well as AC measurements was measured. The power losses are strongly dependent on frequency and excitations.
Keywords:
41CrMo4 steel; magnetic properties; electrical resistivity
Available at various institutes of the ASCR
MAGNETIC AND TRANSPORT PROPERTIES OF 41CRMO4 STEEL
We have measured magnetic parameters and electrical resistivity of 41CrMo4 steel. It consist ferrite, Cr7C3 and Cr23C6 type of carbides. The\nmeasurements of temperature dependences of magnetic ...
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