Site:               Nagoya University
                    Furo-Cho, Chikusa-ku
                    Nagoya 464-01, Japan

Date Visited:       January 10, 1996

WTEC Attendees: D. Bertram (report author), D. Apelian, G. Holdridge Host: Prof. Shigeo Asai, Department of Materials Processing Engineering

BACKGROUND

Professor Asai's work focuses on the application of electromagnetic fields to the processing of materials. He reviewed the basic ideas of some his research projects during our visit. His work is well supported by the Ministry of Education (Monbusho), as well as the MITI.

The Department of Materials Processing Engineering has 16 professors, approximately 50-60 graduate students, and approximately 100 undergraduates per year. Prof. Asai has three assistant professors and an assistant working full time on research. He personally spends 80% of his time on research.

CURRENT MANUFACTURING PRACTICES

Although not developed by Prof. Asai, Nippon Steel is currently experimenting with continuous casting clad stainless steel over a carbon steel core. The process produces a fine definition and bonding between the two materials and thereby allows rolling to a much thinner gauge. The fine definition is produced by a magnetic field that keeps the two liquids separated (suppressing convection) in the caster's mold. Conventional methods of producing clad material produce a bond by hot rolling sheets together or expensive plasma spraying. Prof. Asai showed the WTEC team a 170 mm x 800 mm sample/test piece made by Nippon Steel.

RESEARCH AND DEVELOPMENT ACTIVITIES

Prof. Asai indicated that funding for researchers' salaries is generally not included in Monbusho research project budgets. Researcher salaries are also not reported in Monbusho aggregate research funding reports.

The "regular" Monbusho research allocation for Asai's group at Nagoya is about ¥5-6 million/year. This allocation supports research conducted by Prof. Asai and four other people. The 12 month salaries for those five people combined add up to another approximately ¥5 million/year. Based on the above figure, this means that Monbusho reports his research at ¥5-6 million/year, whereas the real cost is probably much higher. Prof. Asai teaches 2 classes each week; his other four people don't teach at all (though they may help him occasionally with his classes).

Prof. Asai recently received a $200,000 increment for his research projects from Monbusho. This covers two years.

In addition to the above, Prof. Asai receives approximately ¥5 million/year from industry for R&D support.

Last year's economic stimulus package from MITI included $100 million for R&D -- about 100 projects at $1 million each. Prof. Asai did not receive funding under that initiative.

MITI has provided funding for a "soft contact steel casting project" utilizing magneto-hydrodynamics (MHD) for steel casting. The budget is $24 million over six years, beginning in FY 1995. This project budget is allocated among nine Japanese steel companies. This relates directly to Asai's work in use of electromagnetic force for metals processing. The project is being managed for MITI by the Japanese Research and Development Center for Metals (JRCM), which is in Tokyo. The JRCM is an association of Japanese metal companies cooperating on pre-competitive R&D. The director of JRCM at the time of the WTEC visit was a former VP of Nippon Steel.

Prof. Asai sits on an advisory committee appointed by the International Superconducting Technology Center (ISTEC) to evaluate possible applications of very large size, very strong field supermagnets. (ISTEC is funded by MITI.) Presumably a new MITI R&D program may stem from this at a later date.

Professor Asai discussed a number of his current projects -- cold-crucible melting (for TiAl), soft-contacting solidification, synchronizing imposition of a magnetic field with mold oscillation, inclusion removal from liquid metals, the movement of primary silicon in hypereutectic Al-Si alloys, and the application of magnetization force for non-metallic components

The following is a discussion of these projects. Because of project inter-relations this narrative of Prof. Asai's discussion cuts across a number of the specific topics listed previously.

  1. A project involving soft contact solidification through the use of magnetic fields with oscillating molds is a major undertaking. This steel industry program is funded by Nippon Steel, Kobe Steel, Sumitomo, NKK, Kawasaki, Daido, Nissin Steel Co., Mitsubishi Steel Co., and Mitsubishi Heavy Industries in conjunction with JRCM. The project is significant in that if it is fully implemented it could reduce Japan's total energy consumption by 0.2%. MITI alone is committing $24 million over a six year period. The concept is to roll steel plate while it is still hot after casting. The simultaneous application of a magnetic field synchronized with mold oscillation is designed to improve the surface of the slab and thus eliminating the need for scarfing and reheating prior to rolling.
    The improved surface is achieved by soft contact solidification, which means that the slab barely touches the surface of the casting mold and consequently oscillation marks are eliminated and subsequent scarfing in the cold condition is not required. Synchronous imposition of a magnetic field during the negative strip of the mold oscillation is being considered. Considerable work is still required to commercialize this technology.
    Application of controlled electromagnetic forces makes this process possible. The high level of research activity and funding for this study will certainly increase the knowledge base in general, and there will be fallout to the benefit of other metallurgical processes.
  2. Levitation melting (cold crucible melting) is being developed to eliminate contact between the material being melted and the crucible. This non-contact approach improves the potential for high purity since the process can be done in vacuum or a special atmosphere. Features being developed include control of the electromagnetic forces such that levitation and shape control of the "melt" is achieved without producing turbulence within the hot liquid. TiAl compounds and alloys are the current subject materials.
    Although the emphasis is currently on high temperature melting where a suitable non-reactive crucible is currently not available, this may well have application in high volume production for single-shot melting applications in die casting.
  3. Separation of nonmetallic inclusions is difficult by flotation or gravity where the density of the inclusion is close to the density of the clean metal. A theoretical analysis indicates that a direct magnetic field magnifies the difference between metallic and nonmetallic particles and aids in separation. Lab experiments also demonstrate the process' ability to reduce the silicon and iron content of molten aluminum. Prof. Asai holds a patent on this process.

Additional details on these concepts are provided in a number of published technical papers. (See references below.)

This technology when commercialized could make widespread use of contaminated aluminum scrap feasible for critical casting applications.

SUMMARY

Funding from the Japanese government is significant since some of Asai's work could well produce significant energy saving for the country. This is an example of Japan focusing its research and development funding on specific problem-solving situations.

Other benefits from these research projects will be in the improved filtration and refinement of non-ferrous alloys.

Although research funding is significant, improvements to the physical plant at Nagoya University also might help attract much needed additional scientific talent to metal casting research.

REFERENCES

Asai, Shigeo. 1989. "Birth and Recent Activities of Electromagnetic Processing of Materials." ISIJ International, Vol. 29 No. 12, pp. 981-992.

Iwai, Kazuhiko, Tamaoki, Ryouji, Sassa, Kensuke, and ASAI, Shigeo. 1993. "Development Of An Induction Melting Process For Materials With Low Electrical Conductivity Or High Melting Point." Metallurgical Transactions B, Volume 24B, April, p. 259.

Li, Tingju, Nagaya, Shinji, Sassa, Kensuke and Asai, Shigeo. 1995. "Study Of Meniscus Behavior and Surface Properties During Casting in a High-Frequency Magnetic Field." Metallurgical And Materials Transactions B, Volume 26B, April, p. 353.

Park, Joon Pyou, Tanaka, Yosiko, Sassa, Kensuke and Asai, Shigeo. 1994. "Elimination of Tramp Elements in Molten Metal using Electromagnetic Force". International Symposium on Electromagnetic Processing of Materials, Nagoya, ISIJ.

Park, Joon-Pyou, Sassa, Kensuke and Asai, Shigeo. 1995. "Improvement Of Wear-Resistance In Hyper-Eutectic Al-Si Alloy By Surface Concentration Of Primary Silicon Using Electromagnetic Force." Journal of the Japan Inst. Metals, Vol. 59, No. 7, pp. 733-739.

Park, Joon-Pyou, Sassa, Kensuke and Asai, Shigeo. 1995. "Elimination Of Iron In Molten Al-Si Alloys By Electromagnetic Force." Journal of the Japan Inst. Metals, Vol. 59, No. 3, pp. 312-318.

Tanaka, Yoshiko, Sassa, Kensuke, Iwai, Kazuhiko and Asai, Shigeo. 1995. "Separation Of Non-Metallic Inclusions From Molten Metal Using Traveling Magnetic Field."

Takasu, Tomio, Sassa, Kensuke and Asai, Shigeo. 1993. "A Glass Melting By Use Of A High Frequency Induction Skull Melting Method With Submerged Heating Elements And Its Heat Conduction Analysis."


Published: March 1997; WTEC Hyper-Librarian