Relaxation of internal stress generated in hydrogen absorbing alloy vessels

Nasako, K.; Ito, Yoshimasa; Hiro, Naoki; Osumi, Masato

doi:10.1016/s0360-3199(97)00158-4

Cited by 13 publications

(4 citation statements)

References 8 publications

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“…They then proved that the stress accumulation depend on the amount of hydrogen absorption/ desorption cycles and on the initial packing rate. Other experimental studies also proved that the actual stress could rise up acutely with the increase of localized relative density, depth of reactor and cycle number et al [4][5][6]. As a conclusion, the pulverization-densification mechanism is proposed and widely accepted: during the process of hydrogen absorption/desorption cycles, since the metal hydrides powder is crushing up gradually, the finer and finer particles becomes gathering into to the bottom of the reactor under the pull of gravity, which finally cause the localize relative density of metal hydrides powder to increase and self-densification to take place after several repeated manner [4].…”

Section: Introductionmentioning

confidence: 88%

Mechanism Analysis on Stress Accumulation in Cylindrical Vertical-Placed Metal Hydride Reactor

Hu¹,

Qi²,

Qin³

et al. 2011

EPE

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It's known that the pulverization-densification mechanism of metal hydride may cause the stress accumulation in metal hydrides reactors. In this paper, this idea is proved based on granulometry and a new idea of cycling compression effect is presented, which is caused by the friction between wall and metal hydrides. Through theoretical analysis, the cycling compression effects is shown to increase the localized packing rate from top to down in vertical-placed reactors and thus lead to the maximum deformation in the bottom of reactors, proving that it is the interaction of pulverization-densification effect and cycling compression effect resulting in the stress problems of vertical-placed reactors. Further study points that the effective methods relieving the cycling compress effect are to decrease hydrogen absorption/desorption cycle number, slenderness ratio of reactor, wall friction factor and initial packing rate, or to lower the thermal conductivity and the volume expansion coefficient of metal hydrides.

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Section: Introductionmentioning

confidence: 88%

Mechanism Analysis on Stress Accumulation in Cylindrical Vertical-Placed Metal Hydride Reactor

Hu¹,

Qi²,

Qin³

et al. 2011

EPE

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“…The X-ray diffraction (XRD) profiles of as-fabricated and electrochemically-cycled electrodes using the alloy, Mm 0 (Nasako et al 1998;Qin et al 2008). After the discharge process, a small increase in the unit cell volume ( V) is found in the alloy of the electrochemically-tested electrode as compared to the alloy of the as-fabricated electrode, due to residual hydrogen.…”

Section: Structural and Microstructural Characterizationmentioning

confidence: 99%

Iron-substituted AB5-type MH electrode

Srivastava¹,

Upadhyaya²

2013

Bull Mater Sci

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The present investigation is aimed to study MmNi 5-type (Mm = Mischmetal) hydrogen storage alloys with composition, Mm 0•8 La 0•2 Ni 3•7 Al 0•38 Co 0•3 Mn 0•6−x Mo 0•02 Fe x (x = 0, 0•1, 0•2 and 0•3). The alloys are synthesized by radio-frequency induction melting. To study their electrochemical properties via measurements of discharge capacity, activation process, rate capability and cyclic stability, electrodes are fabricated using as-synthesized and annealed version of the alloys. The maximum discharge capacity is recorded as 288 mAhg −1 for the iron concentration, x = 0•1, as compared to 270 mAhg −1 for the alloy electrode without iron. Similarly, 99% cyclic stability is observed in annealed alloy electrode (x = 0•1) as compared to 78% in the alloy electrode without iron. Hence, small amount of iron-substitution (x = 0•1) in the alloy is found to improve the electrochemical properties. This improvement is thought to be due to less pulverization of the alloy in electrochemically-cycled alloy, as confirmed through structural and microstructural characterizations carried out by X-ray diffraction phase analysis and scanning electron microscopy of as-fabricated and electrochemically-cycled electrodes.

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“…During the hydriding/electrochemical charging process, hydrogen atoms enter the alloy lattice and result in lattice expansion [21,22]. Because of this expansion, the unit cell volume also increases.…”

Section: Structural Characterizationmentioning

confidence: 99%