Development of Chemical Vacuum Pump usingNitrogen Absorption Nano-Materials

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The purpose of this study is to develop a handy "Chemical Vacuum Pump" which evacuates from atmospheric pressure to vacuum. In the first year, the Li based alloys, which were produced by mechanical alloying with Si, Cu and Fe, were investigated. For the case of Li-Fe alloy, powders quickly absorb nitrogen gas. However, the amount of absorbed gas is limited, since Li is consumed by the reducing reaction with ion oxides covering the iron powder surface. In the second year, to improve the efficiency, the mechanical milling of Li with oxides which is more stable than lithium oxides were carried out. Thus, the powders milling with alumina and magnesia showed very active reactivity with nitrogen gas. Especially, Li-alumina alloy can absorb air (nitrogen and oxygen), which has not been reported before. In the last year, we also investigated nitrides. In the case of LiaN, it also reacts with oxygen gas showing two stage reactions, much higher than with nitrogen gas. The reason of this characteristic is attributable to the phase transition from alpha-Lis/1 to beta-LiaN and the formation of complex of Li-O-N.