Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
632861 | Journal of Membrane Science | 2015 | 9 Pages |
Abstract
As-cast Nb30Ti35âxHfxCo35 (x=0, 10, and 17.5) alloys consist of a fully lamellar eutectic structure, where the substitution of Ti by Hf induces higher hydrogen solubility and permeability, but poorer embrittlement resistance. Different as-cast alloys were found to be subject to embrittlement failure after hydrogen permeation for 88.3 h (x=0), 71.1 h (x=10) and 16.2 h (x=17.5) at 673 K. In contrast, directionally solidified (DS) Nb30Ti25Hf10Co35 exhibits a substantial enhancement of hydrogen permeability and embrittlement resistance. Typically, DS samples solidified at 1 μm/s show the highest permeability of 4.83Ã10â8 mol H2 mâ1 sâ1 Paâ0.5 at 673 K, which is 1.72 times that of its as-cast counterpart and more than three times that of pure Pd. This sample does not fail during hydrogen permeation for 120 h at 673 K. The high permeability and large embrittlement resistance of DS samples are attributed to their modified eutectic microstructure, which induces a high overall hydrogen diffusivity and a high tolerance to lattice expansion. The present work demonstrates that the directional solidification technique has a high potential to produce high-performance eutectic alloy membranes for hydrogen separation.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Filtration and Separation
Authors
Xinzhong Li, Dongmei Liu, Xiao Liang, Ruirun Chen, Markus Rettenmayr, Yanqing Su, Jingjie Guo, Hengzhi Fu,