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Naoe, Takashi; Oi, Tashiyuki*; Kogawa, Hiroyuki; Wakui, Takashi; Futakawa, Masatoshi
Zairyo, 57(2), p.159 - 166, 2008/02
A mercury target for spallation neutron source will be installed in MLF (Material and Life-science Facility) in J-PARC (Japan Proton Accelerator Research Complex). The mercury target will be suffered from pitting damage by cavitation erosion. The cavitation will be caused through the pressure wave propagation that induced by thermal expansion of the mercury due to proton beam injection. Surface modification to the vessel wall contact with mercury, such as coatings, surface hardening etc., could exhibit prospective potential to suppress the pitting damage. Hence, cavitation erosion tests on surface modified materials in mercury were performed using electro-Magnetic IMpact Testing Machine (MIMTM) to evaluate the resistance against pitting damage. As a result, it was confirmed that crack and separation occurred on coating layer, because of shear stress due to the mechanical properties change in the interface between the coating and substrate layer.
Naoe, Takashi; Futakawa, Masatoshi; Oi, Toshiyuki; Wakui, Takashi; Motohashi, Yoshinobu*
Zairyo, 55(10), p.944 - 950, 2006/10
Mercury target will be installed at the material and life facility in J-PARC. Pressure waves will be generated in mercury by thermally shocked heat deposition when the high intense proton beams bombard the mercury target. Cavitation will be induced through the pressure wave propagation in the mercury and eroded the vessel inner surface contacting with the mercury. The eroded vessel wall is damaged by cyclic fatigue because pulsed proton beams strike the target repeatedly. It is, therefore, important to investigate the fatigue strength of the eroded vessel wall. In order to precisely investigate the effects of damages, at the first, the pitting damage by erosion was evaluated against the number of pulses, and then the fatigue test was carried out using the specimen with a certain pitting damage. As a result, the fitigue limit with pitting damage is degraded to less than half of that without pitting damage, after 2500 hrs operation at 1MW.
Teshigawara, Makoto; Harada, Masahide; Saito, Shigeru; Oikawa, Kenichi; Maekawa, Fujio; Futakawa, Masatoshi; Kikuchi, Kenji; Kato, Takashi; Ikeda, Yujiro; Naoe, Takashi*; et al.
Journal of Nuclear Materials, 356(1-3), p.300 - 307, 2006/09
Times Cited Count：9 Percentile：53.38(Materials Science, Multidisciplinary)We adopted silver-indium-cadmium (Ag-In-Cd) alloy as a material of decoupler for decoupled moderator in JSNS. However, from the heat removal and corrosion protection points of view, the Ag-In-Cd alloy is needed to clad between Al alloys (Al5083). We attempted to obtain good bonding conditions for between Al5083 and ternary Ag-In-Cd alloys by HIPing tests. The good HIP condition was found for small test piece (
20mm). Though a hardened layer due to the formation of AlAg
was found in the bonding layer, the rupture strength of the bonding layer was more than 20 MPa, which was the calculated design stress. Bonding tests of a large size piece (200
20030 mm
), which simulated the real scale, were also performed according to the results of small size tests. The result also gave good bonding and enough required-mechanical-strength, however the rupture strength of the large size test was smaller than that of small one.
Naoe, Takashi; Futakawa, Masatoshi; Oi, Toshiyuki; Ishikura, Shuichi*; Ikeda, Yujiro
Zairyo, 54(11), p.1184 - 1190, 2005/11
High power spallation targets for neutron sources are being developed in the world. Mercury target will be installed at the material science and life facility in J-PARC, which will promote innovative science. The mercury target is subject to the pressure wave caused by the proton bombarding in the mercury. The pressure wave propagation induces the cavitation in mercury that imposes localized impact damage on the target vessel. The impact erosion is a critical issue to decide the lifetime of the target. The electro Magnetic IMpact Testing Machine, MIMTM, was developed to reproduce the localized impact erosion damage and evaluate the damage formation. Additionally, droplet impact analysis was carried out to investigate the correlation between isolate pit profile and micro-jet velocity. We confirmed that value of depth/radius was able to estimate micro jet-velocity. And the velocity at 560W in MIMTM was estimated to be 225
325 m/s. Furthermore, surface-hardening treatments were inhibited pit formation in plastic deformation.
Teshigawara, Makoto; Harada, Masahide; Saito, Shigeru; Oikawa, Kenichi; Maekawa, Fujio; Kikuchi, Kenji; Kato, Takashi; Ikeda, Yujiro; Naoe, Takashi; Oi, Toshiyuki; et al.
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no abstracts in English
