Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7714972 | International Journal of Hydrogen Energy | 2015 | 6 Pages |
Abstract
Microstructural stability and hydrogen permeability in dependence of long-time annealing of both equiaxed (EX) and directionally solidified (DS) Nb30Ti35Co35 eutectic alloys are evaluated. After annealing at 1373Â K for one week, the initially fully lamellar eutectic microstructure of the EX sample has disappeared and changed to a duplex microstructure. This is accompanied by a decrease in hydrogen permeability from 2.65Â ÃÂ 10â8 to 1.08Â ÃÂ 10â8Â mol H2 mâ1sâ1Paâ0.5 at 673Â K. The lower permeability is mainly attributed to the significant reduction of hydrogen diffusivity after annealing. In contrast, DS Nb30Ti35Co35 sample shows higher microstructural stability and much less reduction in hydrogen diffusivity and permeability after annealing. Typically, the hydrogen permeability at 673Â K of the annealed DS sample decreases slightly from 3.58Â ÃÂ 10â8 to 3.24Â ÃÂ 10â8Â mol H2 mâ1sâ1Paâ0.5. The present work demonstrates the superiority of the directional solidification technique in fabricating membranes with high hydrogen permeability in both as-solidified and annealed states.
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Authors
Xinzhong Li, Xiao Liang, Dongmei Liu, Ruirun Chen, Markus Rettenmayr, Yanqing Su, Jingjie Guo, Hengzhi Fu,