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24 results on '"Pushilina, Natalia"'

7. State of the Art in Development of Heat Exchanger Geometry Optimization and Different Storage Bed Designs of a Metal Hydride Reactor.

Author

Kudiiarov, Viktor, Elman, Roman, Pushilina, Natalia, and Kurdyumov, Nikita

Subjects
HEAT exchangers, HYDROGEN storage, HEAT transfer, HYDROGEN content of metals, MASS transfer, HYDRIDES
Abstract

The efficient operation of a metal hydride reactor depends on the hydrogen sorption and desorption reaction rate. In this regard, special attention is paid to heat management solutions when designing metal hydride hydrogen storage systems. One of the effective solutions for improving the heat and mass transfer effect in metal hydride beds is the use of heat exchangers. The design of modern cylindrical-shaped reactors makes it possible to optimize the number of heat exchange elements, design of fins and cooling tubes, filter arrangement and geometrical distribution of metal hydride bed elements. Thus, the development of a metal hydride reactor design with optimal weight and size characteristics, taking into account the efficiency of heat transfer and metal hydride bed design, is the relevant task. This paper discusses the influence of different configurations of heat exchangers and metal hydride bed for modern solid-state hydrogen storage systems. The main advantages and disadvantages of various configurations are considered in terms of heat transfer as well as weight and size characteristics. A comparative analysis of the heat exchangers, fins and other solutions efficiency has been performed, which makes it possible to summarize and facilitate the choice of the reactor configuration in the future. [ABSTRACT FROM AUTHOR]

Published
2023
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12. Hydrogen-induced phase transformation and microstructure evolution for Ti-6Al-4V parts produced by electron beam melting

Author

Pushilina, Natalia, Panin, Alexey, Syrtanov, Maxim, Kashkarov, Egor, Kudiiarov, Viktor, Perevalova, Olga, Laptev, Roman, Lider, Andrey, Koptioug, Andrei, Pushilina, Natalia, Panin, Alexey, Syrtanov, Maxim, Kashkarov, Egor, Kudiiarov, Viktor, Perevalova, Olga, Laptev, Roman, Lider, Andrey, and Koptioug, Andrei

Abstract

In this paper, phase transitions and microstructure evolution in titanium Ti-6Al-4V alloy parts produced by electron beam melting (EBM) under hydrogenation was investigated. Hydrogenation was carried out at the temperature of 650 °C to the absolute hydrogen concentrations in the samples of 0.29, 0.58, and 0.90 wt. %. Comparative analysis of microstructure changes in Ti-6Al-4V alloy parts was performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Furthermore, in-situ XRD was used to investigate the phase transitions in the samples during hydrogenation. The structure of Ti-6Al-4V parts produced by EBM is represented by the α phase plates with the transverse length of 0.2 µm, the β phase both in the form of plates and globular grains, and metastable α'' and ω phases. Hydrogenation to the concentration of 0.29 wt. % leads to the formation of intermetallic Ti3Al phase. The dimensions of intermetallic Ti3Al plates and their volume fraction increase significantly with hydrogen concentration up to 0.58 wt. % along with precipitation of nano-sized crystals of titanium δ hydrides. Individual Ti3Al plates decay into nanocrystals with increasing hydrogen concentration up to 0.9 wt. % accompanied by the increase of proportion and size of hydride plates. Hardness of EBM Ti-6Al-4V alloy decreases with hydrogen content.

Published
2018
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13. Influence of Manufacturing Parameters on Microstructure and Hydrogen Sorption Behavior of Electron Beam Melted Titanium Ti-6Al-4V Alloy

Author

Pushilina, Natalia, Syrtanov, Maxim, Kashkarov, Egor, Murashkina, Tatyana, Kudiiarov, Viktor, Laptev, Roman, Lider, Andrey, Koptioug, Andrei, Pushilina, Natalia, Syrtanov, Maxim, Kashkarov, Egor, Murashkina, Tatyana, Kudiiarov, Viktor, Laptev, Roman, Lider, Andrey, and Koptioug, Andrei

Abstract

Influence of manufacturing parameters (beam current from 13 to 17 mA, speed function 98 and 85) on microstructure and hydrogen sorption behavior of electron beam melted (EBM) Ti-6Al-4V parts was investigated. Optical and scanning electron microscopies as well as X-ray diffraction were used to investigate the microstructure and phase composition of EBM Ti-6Al-4V parts. The average alpha lath width decreases with the increase of the speed function at the fixed beam current (17 mA). Finer microstructure was formed at the beam current 17 mA and speed function 98. The hydrogenation of EBM Ti-6Al-4V parts was performed at the temperatures 500 and 650 degrees C at the constant pressure of 1 atm up to 0.3 wt %. The correlation between the microstructure and hydrogen sorption kinetics by EBM Ti-6Al-4V parts was demonstrated. Lower average hydrogen sorption rate at 500 degrees C was in the sample with coarser microstructure manufactured at the beam current 17 mA and speed function 85. The difference of hydrogen sorption kinetics between the manufactured samples at 650 degrees C was insignificant. The shape of the kinetics curves of hydrogen sorption indicates the phase transition alpha(H)+beta(H)->beta(H).

Published
2018
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16. Stydying of morphology and elemental composition of the calcium phosphate layer after treatment by impulse electron beam

Author

Chudinova, Ekaterina Aleksandrovna, Surmeneva (Ryabtseva), Maria Alexandrovna, Pushilina, Natalia Sergeevna, Teresov, A. D., Grubova, Irina Yurievna, Surmenev, Roman Anatolievich, and Tsepilova, Anna Vladimirovna

Subjects
элементный состав, адгезионные свойства, импульсные пучки, кальций-фосфатные покрытия, морфология, биосовместимые покрытия
Abstract

One of the effective ways to improve the adhesive properties of biocompatible coatings on implants is using electron-beam melting of the surface, accompanied by a partial or complete mixing area "coating- substrate". The surface of the titanium substrate bearing calcium phosphate coating received by RF magnetron sputter is processed by a pulsed electron beam having an energy density of 0.8 - 8 J/cm2. After treatment by a pulsed electron beam under different regimes significant changes in the topography of the formed surface were observed. Treatment regimes with an energy density of 0.8 J/cm{2} and 3 lead to the thermal annealing of the coating. The use of a beam having an energy density of 8 and 6.5 J/cm{2} leads to partial vaporization and mixing of the coating material with a titanium matrix.

Published
2014

23. Investigation of ZrO2 and TiO2 Coatings Influence on Hydrogen Sorption Behavior by Zirconium Alloy Zr1%Nb at Saturation from Gas Atmosphere

Author

Chernov, Ivan P., Pushilina, Natalia S., Kudiiarov, Viktor N., Berezneeva, Ekaterina V., Nikolaeva, Aleksandra N., and Krysina, Olga V.

Abstract

Hydrogen sorption, structural phase state and mechanical properties after hydrogenation of zirconium alloy Zr1%Nb with ZrO2 and TiO2 coatings were investigated. It has been established that ZrO2 coating reduces the rate of hydrogen sorption by zirconium alloy Zr1%Nb in comparison with the initial material at hydrogen saturation temperature 450 °С.

Published
2015
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24. First-Principles Calculations and Experimental Study of H + -Irradiated Zr/Nb Nanoscale Multilayer System.

Author

Laptev, Roman, Svyatkin, Leonid, Krotkevich, Dmitriy, Stepanova, Ekaterina, Pushilina, Natalia, Lomygin, Anton, Ognev, Sergei, Siemek, Krzysztof, and Uglov, Vladimir

Subjects
BINDING energy, PSEUDOPOTENTIAL method, HYDROGEN content of metals, DENSITY functional theory, GLOW discharges, POSITRON annihilation
Abstract

Nanoscale multilayer coating (NMC) based on Zr/Nb layers (100/100 nm) before and after H+ irradiation was investigated by combining experimental techniques with first-principles calculations. Detailed studies of structural and phase state and defect structure of Zr/Nb NMC were performed using methods of transmission electron microscopy, X-ray structural analysis, glow discharge optical emission spectrometry, and the Doppler broadening spectroscopy using variable energy positron beam. The first-principles calculations of binding energies for hydrogen in metal Zr/Nb layers was carried out by the pseudopotential method within the density functional theory framework. First-principles calculations and experimental data indicate the presence of macro- and microstrains predominantly in the zirconium layers of Zr/Nb NMC. The main feature of the studied Zr/Nb NMC is the predominant hydrogen localization in Zr layers near the interfaces. The annihilation of positrons is shown to occur mainly in the Zr layers in the vicinity of the interface. [ABSTRACT FROM AUTHOR]

Published
2021
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