Hydrogen Energy Batteries Ltd.

Omer, Israel

Hydrogen Energy Batteries Ltd.

Omer, Israel
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Rozenak P.,Hydrogen Energy Batteries Ltd. | Unigovski Ya.,Ben - Gurion University of the Negev | Shneck R.,Ben - Gurion University of the Negev
Energy Materials 2014, Conference Proceedings | Year: 2014

The effects of in situ cathodic charging on the tensile properties and susceptibility to cracking of an AISI type 321 stainless steel, welded by the gas tungsten arc welding (GTAW) process, was studied by various treatments. Appearance of delta-ferrite phase in the as-welded steels in our tested conditions was observed with discontinuous grain boundaries (M23C6) and a dense distribution of metal carbides MC ((Ti, Nb)C), which precipitated in the matrix. Shielding gas rates changes the mechanical properties of the welds. Ultimate tensile strength and ductility are increases with the resistance to the environments related the increase of the supplied shielding inert gas rates. Charged specimens, caused mainly in decreases in the ductility of welded specimens. However, more severe decrease in ductility was obtained after post weld heat treatment (PWHT). The fracture of sensitized specimens was predominantly intergranular, whereas the as-welded specimens exhibited massive transgranular regions. Both types of specimen demonstrated narrow brittle zones at the sides of the fracture surface and ductile micro-void coalescences in the middle. Ferrite δ was form after welding with high density of dislocation structures and stacking faults formation and the thin stacking fault plates with ε-martensite phase were typically found in the austenitic matrix after the cathodical charging process.


Rozenak P.,Hydrogen Energy Batteries Ltd. | Shani E.,Ben - Gurion University of the Negev
Energy Materials 2014, Conference Proceedings | Year: 2014

The novel energy generation, by means of a unique hydrogen production method, creates an opportunity to tackle some important social and environmental factors that determine our sustainable development and personal health. Hydrogen can be produced from a spontaneous chemical reaction in an Al-water system, at a relatively low cost, by bringing aluminum and water into contact, with sodium hydroxide as the catalyst and using an energy source derived from aluminum waste. In our experiments, hydrogen of extremely high-purity was obtained and was used in commercial fuel cell facilities to produce electricity. The hydrogen was produced from recyclable material without supplementary energy and with almost no air pollution. We propose that aluminum technologies for fuel cells could become an integral part of the solution for an economical, clean, low-polluting source of energy. The process is lightweight and largely recyclable and offers opportunities for the commercialization of multiple technologies.


Rozenak P.,Hydrogen Energy Batteries LTD
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2011

The transmission electron microscopy (TEM) and X-ray characterization of lattice distortion forms caused by low-energy Ar+ bombardment of grown thin silicon films on a silicon (001) substrate were studied. The isotropic case (of spherical distortions) takes place in epitaxial silicon "as grown" processes. The intensity distribution consists of two maxima-one from the distorted layer and the other from the original unaffected silicon lattice. Significant changes in the 2θ location, peak broadening, and integrated intensity from the (004)*reflections were obtained as functions of aging temperatures. First, aging heat treatment, affects the distribution of distortions obtained from local regions at the "as grown" layer, which changes to a special topography of continued distortions at higher aging temperatures. At aging temperatures above 923 K (650 °C), this extra diffraction peak disappears. The TEM observations reveal the appearance of dislocation lines with dark and bright contrasts around the lines and interdislocation strain contrasts and disorder of Ar atoms in Si matrix regions with coherent interfaces. © 2010 The Minerals, Metals & Materials Society and ASM International.


Rozenak P.,Hydrogen Energy Batteries Ltd.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

Homo-Ge, homo-Si, and hetero-Si0.2Ge0.8 alloy epitaxial layers, using molecular beam epitaxy (MBE), were grown on Ge and Si (001) substrates in order to study development of crystalline strains caused by ion bombardment during the growth of materials. Ion energies and ion/atom fluxes were used in the epitaxial growth, and significant lattice distortions along the growth direction developed. Using high-resolution X-ray diffraction (HRXRD) and high-resolution transmission electron microscopy (HRTEM), the form of distortion, caused by low-energy argon (Ar+) and xenon (Xe +) bombardment of the thin epitaxial films grown on the (001) substrates, were investigated. The isotropic point defects case (of spherical distortions) occurs in epitaxial thin films "as-grown" processes. The intensity distribution has two maxima, one from the distorted layer and the other from the original unaffected matrix. The significant changes in the 2θ location, peak broadening and integrated intensity from the secondary (004)reflections were obtained as a function of aging temperatures in the grown layers. Defects-induced diffuse scattering close to and between Bragg reflections supplies information on the strain and symmetry of the distortions fields and yields the atomic structure of point defects (self-interstitial, vacancies, and small clusters). First, aging heat treatment affects the distribution of distortions obtained in local regions at the "as-grown" layer, which develops to a special topography of continued distortions at higher aging temperatures. At aging temperatures above 923 K (650 C), this extra diffraction peak disappears. The TEM observations reveal the appearance of dislocation lines with dark and bright contrasts around them, interdislocation strain contrasts, and disordered point defects atoms in the silicon region with semicoherent interfaces. The ion bombardment-induced formations and injection of the different types of pointlike defects and defects clusters. © 2012 The Minerals, Metals & Materials Society and ASM International.


Rozenak P.,Hydrogen Energy Batteries Ltd. | Rozenak P.,Ben - Gurion University of the Negev | Unigovski Y.,Ben - Gurion University of the Negev | Shneck R.,Ben - Gurion University of the Negev
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2016

The susceptibility of AISI type 321 stainless steel welded by the gas tungsten arc welding (GTAW) process to hydrogen-assisted cracking (HAC) was studied in a tensile test combined with in situ cathodic charging. Specimen charging causes a decrease in ductility of both the as-received and welded specimens. The mechanical properties of welds depend on welding parameters. For example, the ultimate tensile strength and ductility increase with growing shielding gas (argon) rate. More severe decrease in the ductility was obtained after post-weld heat treatment (PWHT). In welded steels, in addition to discontinuous grain boundary carbides (M23C6) and dense distribution of metal carbides MC ((Ti, Nb)C) precipitated in the matrix, the appearance of delta-ferrite phase was observed. The fracture of sensitized specimens was predominantly intergranular, whereas the as-welded specimens exhibited mainly transgranular regions. High-dislocation density regions and stacking faults were found in delta-ferrite formed after welding. Besides, thin stacking fault plates and epsilon-martensite were found in the austenitic matrix after the cathodic charging. © 2016 The Minerals, Metals & Materials Society and ASM International


Rozenak P.,Hydrogen Energy Batteries LTD
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2014

In austenitic type stainless steels, hydrogen concentration gradients formed during electrochemical charging and followed by hydrogen loss during aging, at room temperature, surface stresses, and martensitic phases α′-BCC and ε-HCP developed. The basic relationship between the X-ray diffraction peak broadening and the hydrogen gradients, formed during charging and aging at room temperature in such austenitic stainless steels, were analyzed. The results demonstrate that the impact of stresses must be considered in the discussion of phase transformations due to hydrogenation. Austenitic stainless steels based on iron-nickel-chromium, have relatively low stacking fault energy γSFE and undergo: quenching to low temperatures, plastic deformation, sensitization heat treatments, high pressure (≥3-5 × 109 Pa) by hydrogen or other gases, electrochemical charging (when the sample is cathode) and when is irradiation by various ions the samples in vacuum. All the above mentioned induce formation of ε and α′ in the face-centered cubic (FCC) austenite γ matrix. The highest stresses cause formation of mainly α′ phase and ε-martensite, and both are involved in plastic deformation processes and promoting crack propagation at the surface. In 310 steel, the crack propagation is based on deformation processes following ε-martensitic formation only. Formations of ε- and α′-martensites were noted along the fracture surfaces and ahead of the crack tip. The cracks propagated through the ε-martensitic plates, which formed along the active slip planes, while α′ phase was always found in the high-stress region on the ends of the ligaments from both sides of the crack surfaces undergoing propagation. © 2013 The Minerals, Metals & Materials Society and ASM International.


Rozenak P.,Hydrogen Energy Batteries Company
TMS Annual Meeting | Year: 2010

The ability of micro-cracks formation in high purity aluminum during electrochemical charging by hydrogen has been studied. The experiments revealed that the existence of a large size distribution of hydrogen bubbles on the surface (blisters) and under the surface obtaining during electrochemical charging can leads to micro-cracks formation in the absence of an external applied stress in aluminum samples. Transmission Electron microscopy (TEM) samples after electrochemically charging showed micro-cracks with typical ductile mode of fracture.


Rozenak P.,Hydrogen Energy Batteries Ltd.
Journal of Alloys and Compounds | Year: 2014

In the present study, the deuterium distribution through the specimen thickness during charging and aging at various temperatures was characterized using the secondary ion mass spectrometry (SIMS) method. The advantages of this method are that the actual concentration-depth profiles are obtained from hydrogen (H) introduced during the growth, storage and melting environments (in single crystal or polycrystalline) of aluminum. Separately, the deuterium (D) concentration-depth profiles introduced from chemical processes or interactions with water during the experimental test processes, obtained by charging was characterized. Analysis of the pores, voids and bubbles related to hydrogen and deuterium was performed by small and wide X-ray scattering (SAXS and WAXS) and by high magnification transmission and scanning electron microscopy (TEM and SEM). Large (some micrometers in diameter) to very small (nanometers in diameter) sizes in the distribution and variability in the density of the voids/bubbles were found. The internal and surface bubbles and dense distributions of voids near dislocations related to the hydrogen distribution were studied. Moreover, the hydrogen-vacancy interactions related to microstructure changes must be taken into account in the process of characterizing the state of hydrogen in aluminum. An interpretation of the two dimensional anisotropic iso-intensities obtained by SAXS for octants voids was coded to obtain iso-intensity in the [1 1 0] plane in reciprocal space. © 2013 Elsevier B.V. All rights reserved.


Rozenak P.,Hydrogen Energy Batteries Ltd. | Shani E.,Ben - Gurion University of the Negev
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

After hydrogen concentration, gradients in austenitic-type stainless steels, formed during electrochemical charging and followed by hydrogen loss during aging at room temperature, surface stresses, and martensitic phases α′-bcc and ε-hcp, developed. Phase quantitative X-ray surface analysis of distributions of martensitic phases in a thin layer, comparable to the penetration depth of X-rays, based on diffraction data taken for various diffraction reflections (2θ, Bragg's angles) and with various radiations (λ-wavelengths) was applied for various degrees of the type steel in the surface layers. An examination of the relationships between γ-phase transitions in a number of stainless steels and their γ stability revealed that the stability of the γ phase increased (S stability factor changed from 26.5 in AISI 321 to 44 in AISI 310), the amount of α′- martensites (from 25 pct in AISI 347 to 0 pct in AISI 310) decreased, and ε-martensites (from 48 pct in AISI 310 to 77 pct in AISI 321) increased, while the depth (from 6.2 μm in AISI 321 to 3 μm in AISI 310) of the martensitic phases decreased. Deformation and fracture experiments were carried out at room temperature in a high-resolution transmission electron microscope with single-axis tilt tensile stage and environmental cell. The principal effect of hydrogen was to decrease the stress required for dislocation motion, for phase transformation of the austenite, and for crack propagation. Formation of ε- and α′-martensite was noted along the fracture surfaces and in front of the crack tip. The cracks propagated through the ε-martensite plates, which formed along the active slip planes, while α′ phase was always found in the high stress regions. © 2012 The Minerals, Metals & Materials Society and ASM International.

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