Multiphase Nb-TiCo alloys: The significant impact of surface corrosion on the structural stability and hydrogen permeation behaviour
Multiphase Nb-TiCo alloys: The significant impact of surface corrosion on the structural stability and hydrogen permeation behaviour
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多相 Nb-TiCo 合金：表面腐蚀对结构稳定性和氢渗透行为的显着影响
DOI：
10.1016/j.ijhydene.2019.04.253
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发表时间：
2019
影响因子：
7.2
通讯作者：
Sun Lixian
中科院分区：
文献类型：
--
作者：
Yan Erhu;Min Ruonan;Huang Haoran;Zhao Ping;Huang Pengru;Zou Yongjin;Chu Hailiang;Sun Shuhui;Sun Lixian
复相NbxTi(100-x)/2Co(100-x)/2(x=0.30-60)合金是一种很有前途的氢分离膜材料。为解决这一问题，采用表面腐蚀的方法在Pd涂层和Nb-TiCo衬底之间形成致密的氧化层(如Nb_2O_5、TiO_2和CoO)以提高其热稳定性，并研究了Nb-TiCo合金的耐蚀性能。随着Nb含量(X)的增加，合金的耐蚀性降低，但更容易形成上述氧化层。经腐蚀后的合金(x=30和40)在773K时的氢渗透率和热稳定性显著提高，这可归因于氢扩散系数的增加。这种改善的渗透性和稳定性与上述阻碍Pd膜和Nb-TiCo基片之间互扩散的表面氧化层的形成密切相关。这项研究表明，通过表面腐蚀在Pd和Nb基衬底之间插入扩散势垒是提高Pd涂层Nb-TiCo合金高温稳定性的一种可行的方法，这一方面在Nb基氢分离和净化膜中尚未被广泛探索。
Multiphase NbxTi(100-x)/2Co(100-x)/2(x = 30–60) alloys are a promising material for hydrogen separating membranes. These alloy membranes exhibit a rapid decline in hydrogen permeation flux within ∼12 h when operated at 773 K. To address this issue, a dense oxide (e.g. Nb2O5, TiO2and CoO) layer was prepared between a Pd coating layer and an Nb–TiCo substrate by surface corrosion for improving their thermal stability, and the corrosion resistance of Nb–TiCo alloys was investigated. An increase in the Nb content (x) lowers the corrosion resistance of these alloys, but makes it easier to form the above oxide layer. Substantial enhancement of hydrogen permeability and thermal stability at 773 K was observed for the alloys (x = 30 and 40) after corrosion, which can be ascribed to an increase in hydrogen diffusivity. This improved permeability and stability are closely related to the formation of the above surface oxide layer that impeded interdiffusion between the Pd film and Nb–TiCo substrates. This study demonstrates that insertion of a diffusion barrier between the Pd and Nb-based substrates by surface corrosion is a viable approach to enhance the high-temperature stability of Pd-coated Nb–TiCo alloys, an aspect not widely explored in Nb-based hydrogen separation and purification membranes.