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Room: Salon 8
Location: Clarion Plaza Hotel
Session Chairpersons: Barry T. Kilbourn, Molycorp, Inc., Executive 46 Office Center, 710 Route 46, East Fairfield, NY 07004; Charles O. Bounds, Rhone-Poulenc, Rare Earths and Galliu, CN 7500, Cranbury, NJ
MAGNETIC REFRIGERATION: Karl A. Gschneidner, Jr. and Vitalij K. Pecharsky, Ames Laboratory and Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-3020
Magnetic refrigeration is based on the magnetocaloric effect (MCE), i.e. the temperature change (usually an increase) of a magnetic material near its mag netic ordering temperature due to the application of an external magnetic field. For many lanthanide materials the temperature increase is sufficiently large that one can utilize these materials as magnetic refrigerants. The best materials are those which order ferromagnetically and contain a heavy lanthanide metal Gd, Tb, Dy, Ho, or Er, and possibly Nd, since the available magnetic entropy, and therefore, the cooling power is proportional to the total quantum number, J. Generally antiferromagnetic, ferromagnetic and spin glass behaviors are not nearly as effective as ferromagnetic ordering. Studies to date have indicated that the MCE can be used as a method for the ligquefaction of cryogenic gasses, freezers for food processing plants, supermarket chillers and large scale building air conditioning.
RARE EARTH RAW MATERIALS AND APPLICATION MARKETS: A BALANCING ACT: J.M. Tourre, Rhône-Poulenc Rare Earth and Gallium 25 Quai Paul Dourmer, 92408 Courbevoie Cedex, France
1995 has seen a continuation of a positive trend in the Rare Earth industry. The availability of greater diversity of raw materials has brought additional flexibility to the producers permitting better economics. China remains the major raw material source; Chinese concentrate producers have increased capacity in 1995 (Baotou, Sichuan, etc..). China's role in the Rare Earth industry will continue to evolve; the acquisition of a majority equity position in Magnequench by San Huan will have significant impact on both the Rare Earth and Magnet markets. Chinese producers are increasing the quality of their products and realize their true values. The Chinese market, itself, is also changing as the internal needs for the separated rare earths grow.
THE COMMERCIAL SIGNIFICANCE OF MIXED-LANTHANIDE DERIVATIVES: Barry T. Kilbourn, Molycorp, Inc., Fairfield, N.J
It is not widely appreciated that, currently, the largest consumption byfar of lanthanides is in mixed-lanthanide forms. Such forms are based on either "natural-ratio" or "modified natural-ratio" materials, where the "natural-ratio"
is the inherent blend of the Ln elements in the dominant ore bodies. The reason for the choice of mixed-lanthanides is simplesuch forms are the most economical. The same economics will obviously apply to new technologies under development such as, for example, solid oxide fuel systems based on lanthanide-containing ceramics and nickel-lanthanide hydride battery systems. Their commercialization depends on the availability and the economic accessibility of suitable raw materials, and, in many cases, that will mean using mixed-lanthanide derivativesnot pure lanthanide compounds. The production process from ore to mixed-lanthanide derivatives will be traced.
10:00 am BREAK
Re-BASED METAL HYDRIDES AND NiMH RECHARGEABLE BATTERIES: L.Y. Zhang, Ph.D., Energizer Power Systems, Gainesville, FL 32614
The current status of metal hydride alloys for NiMH batteries was systematically reviewed. Extensive application-oriented R&D has successfully made the NiMH batteries an important part, with growing potential, among rechargeable batteries. The rare earth-based metal hydrides (AB5) have been considered the best alloy material for use in the negative electrode in NiMH batteries. However, being in demand for high performance by electronic markets, the still young NiMH industry is facing serious technical challenges in developing better products. Among other efforts to respond to the challenges, advanced AB5 alloys are in great demand: the capacity enhancement race requires new or improved alloys processing higher volumetric capacity; high corrosion resistance when subjected to electrochemical cycling. Finally, price competition mandates MH materials with ow cost.
HIGH PERFORMING Sm(Co,Fe,Cu,Zr)z POWDERS FOR THE BONDED MAGNET APPLICATION: W. Gong, B.M. Ma, and C.O. Bounds, Rhône-Poulenc, Rare Earths and Gallium, CN 7500 Cranbury, NJ 08512
The outstanding thermal stability and high energy product make Sm (Co,Fe,Cu,Zr)z type alloys attractive for advanced applications. The near net-shape production of Sm(Co,Fe,Cu,Zr)z bonded magnets make them potentially superior to any magnets made by sintering. Although pioneering work done by Shimoda et al. And other investigators provide insights on the nominal compositional selection and process control of this alloy system, additional work is still necessary to improve our understanding of alloy behavior at various processing stages and to increase the production yield during powder processing. In this paper we report on the development of anisotropic Sm(Co,Fe,Cu,Zr)z alloy powders for the bonded bonded magnet application.
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