| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The applicability of hydrogen gettering alloys is rather limited at present. This is due to their high reactivity against impurity gases, especially to oxygen containing molecules as H_2O,CO_2, CO and O_2, which appear most often in vacuum systems. One solution of this problem is to prepare surface protective layrs on active materials which are free from contamination by the impurity gases and act as permeation window for hydrogen isotopes. To develop such protective layrs, we have studied physicochemical properties of a Pd-overlayr propared with electroless plating on Zr-based alloy, Zr_3Al_2. In the present study, the average thickness and growth rate of the Pd-overlayr was estimated to 2.5 mum and 2.5 mum/hr, respectively. Its morphology was altered by sintering. In addition, mutual diffusion between plated Pd and substrate elements, Zr and Al, took place above 600ﾟC by annealing. However, coated Pd kept pure metallic state at the annealing temperature range from room temperature to 900ﾟC,whereas Zr changed from metallic to carbide states above 700ﾟC by the interactions with surface carbon impurities. Exposure of CO_2 and N_2 caused the reduction of the absorption rate of deuterium. However, the extent of the reduction for Pd/Zr_3Al_2 was smaller than that of bare Zr_3Al_2, indicating that the Pd-overlayr is effective against impurity gases. The order of the effectiveness of the Pd-overlayr against impurity gases was N_2 > CO_2. This could be explained in terms of differences in the absorption properties of deuterium between Pd and Zr.
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