Optimizing niobium dealloying with metallic melt to fabricate porous structure for electrolytic capacitors

Joung Wook Kim, Masashi Tsuda, Takeshi Wada, Kunio Yubuta, Sung Gyoo Kim, Hidemi Kato

研究成果: Contribution to journalArticle査読

49 被引用数 (Scopus)

抄録

The transition behavior from a Nb-Ni precursor to porous Nb and the coarsening of ligaments by a dealloying reaction in a Mg melt are investigated. Based on these results, the kinetics of the reaction are discussed. When a Nb25Ni75 (at.%) disk was immersed in a Mg melt, the Ni content decreased the most at the surface of the disk and less so towards the interior of the disk. In this disk, it was found that transition layers of body-centered cubic-Nb and Ni6Nb7 formed. These transition layers grew, following a parabolic law, and the activation energy of such growth was close to values reported for the diffusion of solute atoms in liquids, suggesting that diffusion of Ni in the Mg melt was the rate-controlling process of the dealloying reaction. The ligament size depended on time and temperature, following a power law with an exponent of 4, suggesting that surface diffusion was a key part of coarsening. These results agree well with those reported for conventional dealloying in an aqueous solution. Based on the kinetics analyses, the dealloying conditions were optimized to maximize the specific surface area, allowing a Nb electrolytic capacitor to be produced with a maximum mass-specific capacitance of 650,000 μFV g-1, about three times larger than the highest value previously reported.

本文言語英語
ページ(範囲)497-505
ページ数9
ジャーナルActa Materialia
84
DOI
出版ステータス出版済み - 2 1 2015
外部発表はい

All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • セラミックおよび複合材料
  • ポリマーおよびプラスチック
  • 金属および合金

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