Papers by Author: M. Kondo

Abstract: The microstructure and hydrogenation property of hyper-eutectic Mg-Ni alloys were investigated. The specimens were Mg-31 mass%Ni, Mg-41 mass%Ni and Mg-50 mass%Ni alloys that are composed of primary Mg2Ni crystal and Mg-Mg2Ni eutectic structure. The amount of the primary Mg2Ni phase increased as the content of Ni increased. The hydrogenation behavior strongly depended on the Ni content and the number of the hydrogenation cycle, that is, as the increase of the Ni content in the specimen, the hydrogen absorption rate increased while the hydrogen absorption weight decreased. At the first cycle measurement, hydrogen absorption was slow for the Mg-31 mass%Ni alloy while hydrogen was rapidly absorbed for the Mg-50 mass%Ni alloy at 300°C. In all the specimens, saturation of the hydrogen absorption was achieved within a few minutes after the second cycle measurement. The maximum values of the hydrogen absorption weight decreased from 5.5 mass% to 4.1 mass% as the Ni content increased.

Abstract: Institute of Space and Astronautical Science (ISAS/JAXA) in collaboration with Mitsubishi Heavy Industries (MHI) has developed fuel and gas tanks for reaction control system and orbital control system of satellites; A tank is fabricated through welding of two thin, hemi-spherical or conical parts, which are fabricated by superplastic blow forming. Mass-productivity is not an important factor but the forming precision and flexibiliry in the process are important for this application. ISAS and MHI, therefore, developed a new blow-forming technique, which has high flexibility in terms of tank size because it requires a furnace but not a hot-press machine. Some typical propulsion tanks fabricated through this process are presented.