金属の高純度精製法の開発及び高純度金属の評価 Purification of

三村耕司
准教授
Kouji MIMURA
Associate Professor
東北大学多元物質科学研究所
Institute of Multidisciplinary Research for Advanced Materials Tohoku University
無機材料研究部門
Division of Inorganic Material Research
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高純度金属
高融点金属
高純度精製法
極微量不純物分析
High purity metals
Refractory metals
Purification
Determination of trace impurities
金属の高純度精製法の開発及び高純度金属の評価
Purification of metals and evaluation of high-purity metals
金属本来の性質を解明するには高純度化は重要な要件であるが、さらに実用面でも不純物の悪影響を受け易い高性能デバイ
スや半導体等に用いられる原料には、高純度化が必要不可欠である。金属の高純度化では、目的金属以外の約 80 余の不純
物元素全ての極低減化を図ることが肝要であり、各目的金属に対し効率的かつ実用的な高純度精製法の開発が求められる。
High purity metals are required for investigating their intrinsic chemical and physical properties and, furthermore, are
practically demanded for fabricating various functional devices and semiconductor materials. When producing high
purity metals, the all metallic and non-metallic impurities should be reduced to the very low concentration levels.
Then, more efficient and practical refining and purification methods have to be developed for the respective metal.
新規開発した水素プラズマ溶解精製法は、プラズマ高温内に水素を加え、生成する活性水素Ｈにより優れた精製効果が期待
できる。これまで Fe, Co 等に対する脱酸・脱窒効果が、さらに Ta, Hf 等の高融点金属に対し、高真空溶解と同等以上の精
製効果が確認された。今後、水素量増加や減圧での溶解を試み、精製効果の一層の向上を目指す。
Hydrogen plasma arc melting and refining method (HPAM), which was developed by the addition of H2 to the plasma
generating gas, has been found to be very useful for the removal of oxygen and nitrogen from the melted Fe and Co and,
in addition, for the removal of many metallic impurities from the refractory metal like Ta and Hf. To enhance the
refining effect of HPAM, the increase in the H2 content of plasma gas and the HPAM under a reduced pressure will be
examined.
100
10
10
Fe
1
Si
Fig.1. Hydrogen plasma arc melting and
refining of the melted metal.
S
0.1
V
0.01
Water-cooled
Cu crucible
(1 mass ppm)
Cimpurity / mass ppm
Melted metal
Cimpurity / mass ppm
Ti
Plasma torch
Hydrogen
plasma arc
(H2→2H)
100
1
Al
Se
0.1
Ni
0.01
Sn
(1 mass ppm)
Cu
Co
Cr
Mg
0.001
0
20
40
60
Melting time, t / min
0.001
0
Zn
Mn
20
40
60
Melting time, t / min
Fig.2. Efficient removal of many impurities in Hf metal melted by
hydrogen plasma arc.
金属, 84(2014), 4-10. Mater. Trans., 52(2011), 159-165. Thin solid Films, 519(2011), 8451-8455. ISIJ International, 54(2014), 2421-2424.
[email protected]
http://db.tagen.tohoku.ac.jp/php/forweb/outline.php?lang=ja&no=2055

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