Papers by Keyword: Hydrides

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Authors: Hayao Imamura, Kazuki Yoshihara, Mika Yoo, Ichiro Kitazawa, Yoshihisa Sakata, Shinji Ooshima, Takeshi Kataoka
Abstract: The hydrogen desorption of Sn/MgH2 nanocomposite which is formed by ball milling of MgH2 and tin compounds (Sn, Sn(C4H9)4 or SnCl2), has been studied. The hydrogen desorption properties (desorption temperature and enthalpy of dehydriding) were significantly improved as a result of a Sn/MgH2 nanocomposite formation. TDS (thermal desorption spectrometry), TG (thermogravimetry) and DSC (differential scanning calorimeter) measurements exhibited the existence of at least two types of hydrogen species in the Sn/MgH2 nanocomposite resulting from ball milling of MgH2 with Sn; the one was hydrogen in the newly formed Sn/MgH2 nanocomposite and the other hydrogen derived from MgH2 remaining in Sn/MgH2.
Authors: Young Suk Kim, Kyung Soo Im, Yong Moo Cheong
Abstract: The hydrogen concentration limit and critical temperatures for a delayed hydride cracking (DHC) in zirconium alloys have been reanalyzed using Kim’s DHC model that a driving force for DHC is not the stress gradient but the supersaturated hydrogen concentration or ∆C arising from a hysteresis of the terminal solid solubility on a heating and on a cooling. The DHC initiation occurs generally at the temperatures corresponding to the terminal solid solubility for precipititation (TSSP), demonstrating that the supercooling from the terminal solid solubility for dissolution (TSSD) is required to initiate the DHC. The DHC arrest temperatures correspond to the temperatures where the ∆C is reduced to zero. Therefore, we conclude that the ∆C is the driving force for the DHC and that the Kim’s DHC model is feasible.
Authors: X.F. Han, L.Y. Lin, E. Baggio-Saitovitch, R.G. Xu, Xiao Hong Wang, H.G. Pan
Authors: Luzinete Pereira Barbosa, Hidetoshi Takiishi, Rubens Nunes de Faria, Daniel Rodrigues, S.R. Janasi
Abstract: This paper reports the results of investigations carried out to determine the Curie temperature (Tc) of some annealed praseodymium-based alloys represented by the formula Pr14Fe79.9-xCoxB6Nb0.1. The Curie temperature of these permanent magnet alloys increase linearly with the cobalt content at about (10.2±0.3) oC/at%. Pr14Fe80B6 and Pr14Fe79.9B6Nb0.1 magnetic alloys with a Tc of 290oC have been used as a standard reference. Magnets were prepared from the alloys using the hydrogenation, disproportionation, desorption and recombination (HDDR) process.
Authors: Xin Liu, Zhi Yong Mao, Yong Ping Lei
Abstract: Microstructures of electron beam welded joints for TA15 titanium alloy with different hydrogen contents were observed and analyzed by SEM and TEM. And the influence of hydrogen on microstructure of the joints was investigated. The results show that the microstructure of the weld metal is lamellar α+β phase after hydrogen charging. In the range of hydrogen contents discussed in this study (from 0 to 0.101 wt%), With the increase of hydrogen content, there is little change in the appearance of the microstructure of the weld metal. The presence of hydrogen can promote the growth of twins in electron beam welded joints. With the increase of hydrogen content, the number of twins is increased. When hydrogen content reaches to a certainty level, hydrides are found in TA15 electron beam welded joints.
Authors: Mohamed Bououdina, Z. Xiao Guo
Authors: Takashi Murakami, Katsuo Kaneda, Hiroki Mano, Masayuki Hata, Shinya Sasaki, Joichi Sugimura
Abstract: In this study, Zr, Ti and TiC-based cermet specimens were prepared, and their friction and wear properties in various gas atmospheres were examined. The Zr specimens exhibited the lowest friction coefficients and the smallest volume change in the H2 gas atmosphere. This reason would have been due to the formation of the -type Zr hydride, which has a layered crystal structure. The Ti specimens exhibited similar friction and wear properties, although the TiC-based cermet specimens containing small amount of Mo, Ni and W exhibited the lowest friction coefficients in air, not in the H2 gas atmosphere. The low friction coefficients of the cermet specimens in air is likely to have been due to the formation of the low friction Mo oxides and W oxides.
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