Sponsored by: LMD Reactive Metals Committee
Co-sponsored by: Canadian Institute of Mining, Metallurgy & Petroleum, Montreal, Canada; The Japan Institute of Metals, Sendai, Japan; Mining & Materials Processing Institute of Japan, Tokyo, Japan; Society for Mining, Metallurgy & Exploration, Littleton, CO
Program Organizers: B. Mishra, Department of Metallurgical & Materials Engineering., Colorado School of Mines, Golden, CO 80401; G.J. Kipouros, Department of Mining and Metallurgical Engineering, Technical University of Nova Scotia, Halifax, Nova Scotia, Canada B3J 2X4; R.G. Reddy, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, NV 89557
Co- Organizers: W.A. Averill, Rocky Flats, Inc., Golden; R.G. Bautista, University of Nevada - Reno, Reno; M.C. Bronson, Lawrence Livermore Natl. Lab., Livermore; J.A. Sommers, Teledyne Wah Chang Albany, Albany; C.B. Wilson, The Dow Chemical Company, Freeport
Tuesday, AM Room: B9
February 6, 1996 Location: Anaheim Convention Center
Session Chairperson: Dr. B. Mishra, Department of Metallurgical & Materials Engineering, Colorado School of Mines, Golden, CO 80401; Dr. G.J. Kipouros, Department of Mining & Metallurgical Engineering, Technical University of Nova Scotia, Halifax, Nova Scotia, Canada B3J 2X4
MODERN MAGNESIUM PRODUCTION PROCESSES: C.B. Wilson, Magnesium Operations, 2301 N Brazosport Blvd., A-1230, Room 114, Freeport, TX 77541-0286
There are currently two major routes practiced industrially for the production of primary magnesium metal. The first of these is the electrolysis of magnesium chloride and the second is the thermal reduction of magnesium oxide. Within these two major categories, there are many variations of the two technologies which are practiced industrially. The dominate production method is the electrolysis of magnesium chloride and this is practiced by the Dow Chemical Company, Norsk Hydro, Mag Corp., and the plants in the Former Soviet Union. Each of the processes practiced at these facilities uses a different means of feed preparation and this in turn causes the electrolytic cell end of the processes to be different also. The second technology is the thermal reduction of magnesium oxide and there are at least three different variations which are practiced industrially. The first of these is the Pidgeon process which reacts dolime (MgO.CaO) with ferro-silicon (FeSi) to form a di-calcium silicate and magnesium metal at an elevated (about 800[[ring]]C) temperature and reduced pressure in an externally heated retort. This is practiced by Timmenco and produces a very high purity magnesium. The second process reacts the same starting raw materials at a high (about 1100[[ring]]C) temperature in an internally heated reactor under reduced pressure. This is practiced by Brasmag in Brazil. The final variation of the ferro-silicon process is the Magnetherm(TM) process developed by Pechiney and practiced by Pechiney and Alcoa which uses slag resistance heating and very high (about 1550[[ring]]C) temperatures. This paper will examine each of these production methods and discuss both their merits and their weaknesses.
ULTRA HIGH PURITY MAGNESIUM REFINING: R.K.F. Lam, D.R. Marx, Materials Research Corporation, 542 Route 303, Orangeburg, NY 10962
Ultra high purity magnesium was purified by a proprietary vacuum method and apparatus to increase purity by approximately five hundred times in a single step. Purity increased from 99.95% to 99.999%, exclusive of zinc impurity. Properties of starting material and refined material are discussed. A novel purification apparatus was designed and developed for the magnesium refining. The purification process was carried out automatically by a computerized control system, and the system was monitored continuously by a computerized data acquisition system.
PRODUCTION OF HIGH PURITY TITANIUM BY ELECTROREFINING: M. Kanda, K. Sato, E. Kimura, Mitsubishi Materials Corporation, I-297 Kitabukurocho, Omiya, Saitama 330, Japan
The behavior of impurities in electrorefining of Ti by NaCl-KCl-TiClx molten salts and the production process of its molten salts have been studied. As a result, purification of salts, materials for the apparatus and quality of anode Ti were important to produce the high quality Ti. By using purified molten salts and the apparatus constructed of nickel, impurities of the deposited Ti, such as Fe, Ni, could be lowered to about 0.01 ppm. The content of Al, Cr of this Ti were about 0.5 ppm. The volatile impurities were removed from the obtained Ti in this process by the electron beam melting and 6N up grade Ti ingot (except for gas elements) were obtained.
10:00 am BREAK
HYDROGEN STORAGE WITH NANOCRYSTALLINE MAGNESIUM-NICKEL ALLOYS: M.A. Imam, D.A. Meyn, Materials Science & Technology Division, Code 6320, US Naval Research Laboratory, Washington, DC 20375; R.L. Holtz, H. Aaronson, Geo-centers, Inc. 10903 Indian Head Highway, Fort Washington, MD 20744
Of potential practical hydrogen storage materials, pure Mg would be best from the standpoint of hydrogen capacity per unit mass. However, pure Mg has poor hydriding reactivity due to surface oxide poisoning and low catalytic activity. Mg2Ni is an alternative which is much more stable against oxidation and the Ni aids catalysis of the H2 dissociation, but at the expense of a 50% decrease in storage capacity. Empirically, it would seem that an ideal hydrogen storage material would be pure Mg particles coated with a thin layer of Ni. Theoretical considerations suggest that this optimum hydrogen storage material may be realized with nanocrystalline Mg-Ni alloys with Ni concentrations comparable to the maximum solid solubility of Ni in Mg. We have prepared nanocrystalline Mg-Ni alloys in powder and thin film form with various concentrations of Ni by ball-milling and physical vapor deposit, and report on studies of the surface segregation of Ni and on the hydrogen storage characteristics of these pseudoalloys.
EFFECT OF CASTING PARAMETERS ON THE MICROSTRUCTURE OF ASTM F-75 IMPLANT ALLOY: H. Mancha, M. Gomez, J.L. Rodriguez, J. Escobedo, M. Castro, M. Mendez, Centro de Investigaciones y Estudios Avanzado-IPN, Unidad Saltillo, Carretera Saltillo-Monterrey Km. 13, Apdo. Postal No. 663, Saltillo, Coahuila, Mexico
Hip replacement implants fabricated using the ASTM-F75 alloy sometimes fail in a sudden catastrophic way. In general, the fractures start at microstructural defects exposed to chemical attack by body liquids subjected to stress-corrosion. In this paper, the results of a study on the effect of casting parameters on the microstructure are presented. The mold and the liquid temperatures were varied between 900 and 1000[[ring]]C and 1410 and 1470[[ring]]C, respectively. The results show that the volume fraction of eutectic carbides that are present in the microstructure strongly decreases as the mold and/or pouring temperature increase. The volume fraction of "blocky" crabides remains at a high level and in all instances were found located mainly in interdenritic regions. It wa also found that the grain size increases rapidly with increasing mold and pouring temperatures, developing long dendrites that grow from the surface to the center of the bars.
SYNTHESIS OF Sm-Co ALLOYS BY MECHANOCHEMICAL REDUCTION: W. Richmond, W.F. Miao, P.G. McCormick, Research Center for Advanced Mineral and Materials Processing, University of Western Australia, Nedlands, WA 6097, Australia
The synthesis of samarium cobalt alloys from SmCl3 and Co precursor powders by
mechanical milling with Ca or Na has been investigated using x-ray diffraction,
transmission electron microscopy, differential scanning calorimetry and
magnetic measurements. With the synthesis of SmCo5, using Ca as the reductant,
the as milled structure was entirely amorphous. Heat treatment above
800[[ring]]C was required to form the magnetically hard SmCo5 phase.
Procedures for removal of the CaCl2 by-product phase following milling and heat
treatment will be discussed. Attempts to synthesis SmCo5 from SmCl3 and Co
using Na as the reductant resulted in a nanocrystalline mixture of Sm, Co and
NaCl with no evidence for alloying of Sm and Co. In this case, the treatment at
temperatures above 400[[ring]]C resulted in reversion of Sm to SmCl2.
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