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1998 Fiscal Year Final Research Report Summary

Impurity removal kinetics of hydrogen plasma arc melting

Research Project

Project/Area Number 08455344
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Metal making engineering
Research InstitutionTohoku University

Principal Investigator

ISSHIKI Minoru  Tohoku Univ.Inst.for Adv.Mat.Processing, Prof., 素材工学研究所, 教授 (20111247)

Co-Investigator(Kenkyū-buntansha) ISHIKAWA Yukio  Tohoku Univ.Inst.for Adv.Mat.Processing, Research Asist., 素材工学研究所, 助手 (40250823)
MIMURA Kouji  Tohoku Univ.Inst.for Adv.Mat.Processing, Reserach Asist., 素材工学研究所, 助手 (00091752)
Project Period (FY) 1996 – 1998
KeywordsPlasma melting / Hydrogen plasma / Refining / High purity metals / Kinetics
Research Abstract

It has been found that hydrogen plasma arc melting (HPAM) has a strong effect on impurity removal even under an atmospheric pressure. The aim of this study is to clarify the mechanism of impurity elimination during HPAM.The main results are follows.
1. The thermodynamic calculations agree with the experimental data on the impurity elimination. This indicates that hydrogen addition to the argon plasma gas allows the system to achieve the equilibrium like state much faster than argon plasma melting.
2. It is found that the impurity removal mainly depends on the vapor pressure difference between the impurity and the base metal, although several impurities such as Sb, P and O are eliminated in the form of hydrides.
3. Impurity removal obeys the first law reaction and consists of 2 steps with different elimination rates. In the higher concentration range (step 1), elimination rate remarkably increase with the hydrogen concentration of the plasma gas. Hydrogen addition also lowers the impurity concentration at the transition from step 1 to step 2.
4. Impurity elimination of step 1 and 2 are found limited by diffusion through boundary layers in gas phase and metal phase, respectively.
5. Thermodynamic and mathematical simulations clarify that hydrogen addition gives drastic change of the properties and performance of the plasma arc and increases the temperature in the vicinity of the molten metal surface.
6.Finally, HPAM is found to possess an remarkable capability as a new refining method, which is confirmed by applying it to the purification of several metals.

  • Research Products

    (15 results)

All Other

All Publications (15 results)

  • [Publications] D.Elanski: "Purification of tantalum by means of plasma arc metting" Materials Lett.30. 1-5 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.M.Fudolich: "Prediction of surface temperature on metal beads subjected to Argon-hydrogen transferred arc plasma impingement" ISIJ International. 37. 623-629 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Isshiki: "Purification of rareearth metals" Vacuum. 47. 885-887 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] D.Elanski: "Thermodymamicsimulation of systems with refractory metals melted by Ar-Hz plasma" Vacuum. 47. 849-852 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] D.Elanski: "Refining elfect of Ar-Hz plasma arc melting of Nb-based alloy"

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 三村耕司: "高純度化技術体系第2巻(P.887〜94)特殊溶解(電子溶解プラズママーク溶解)" フジテクノシステム, 1019 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] D.Elanski: "Refining effect of Ar-H_2 plasma arc melting of Nb-based alloy" Vacuum. 47.No.6-8. 845-847 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] D.Elanski: "Thermodynamic simulation of systems with refractory metals melted by Ar-H_2 plasma" Vacuum. 47.No.6-8. 849-852 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M.Isshiki: "Purification of rare earth metals" Vacuum. 47.No.6-8. 885-887 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] D.Elanski: "Purification of tantalum by means of hydrogen plasma arc melting" Materials Lett.30. 1-5 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.M.Fudolich: "Prediction of Surface Temperature on Metal Beads Subjected to Argon-Hydrogen Transferred Arc Plasma Impingement" ISIJ Intern.37-6. 623-629 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] D.Elanski: "Impurity Removal from Metals by Ar-H2 Plasma Arc Melting - Part I,Melting of Zr, Nb and Ta -" (Submitted).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] D.Elanski: "Impurity Removal from Metals by Ar-H2 Plasma Arc Melting - Part II,Melting of Fe, Cr, Ti and V -" (Submitted).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] D.Elanski: "Impurity Removal from Metals by Ar-H2 Plasma Arc Melting - Part III,Comparison of purification effect among seven base metals and possibility of hydride formation-" (Submitted).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Mimura: "Deoxidation and Denitrogenization of Iron and Cobalt by Hydrogen-Argon Plasma Arc Melting" (Submitted).

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-12-08  

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