カソード分極中におけるアノード酸化皮膜化成ニオブ電極への水素吸収 [in Japanese] Hydrogen Absorption into Anodized Niobium Electrodes during Cathodic Polarization [in Japanese]
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Cathodic polarization of niobium specimens that have been anodized galvanostatically up to E<sub>a</sub>=100V, and then potentiostatically at E<sub>a</sub>=100V has been investigated in a neutral borate solution. During potetiostatic cathodic polarization below E<sub>c</sub>=−2.36V (vs. RHE) in both aerated and deaerated solutions, the cathodic current increased rapidly initially, and then increased gradually until it reached a steady value. Hydrogen gas evolution was observed during cathodic polarization below E<sub>c</sub>=−2.36V with no formation of blisters and pits, suggesting that H<sup>+</sup> reduction occurs mainly at the film surface. GD-OES spectra revealed that hydrogen species are enriched in the niobium substrate near the interface between anodic oxide films and the substrate at potentials below E<sub>c</sub>=−2.36V, and that the trend is pronounced at lower potentials. Chemical shift was observed on Nb 3d and O 1s peaks in XPS spectra for the specimen at E<sub>c</sub>=−3.36V, suggesting the formation of Nb<sub>2</sub>O<sub>3</sub>(OH)<sub>2</sub>.<br>Mechanism for the reaction during cathodic polarization in a neutral solution is discussed in terms of the proton reduction at the interfaces both between oxide films / solutions and between oxide films / substrates.
- Jitsumu Hyomen Gijutsu
Jitsumu Hyomen Gijutsu 59(5), 326-332, 2008-05-01
The Surface Finishing Society of Japan