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Anisotropic forming of magnetic powders mixed with ultra-violet resin
Electrical materials
and magnetic
PM SOFT MAGNETIC MATERIALS FOR AUTOMOTIVE APPLICATIONS D.R.Ryan et al. (Windfall Products Inc, St. Mary’s, USA.) Int. J. Powder Metall., Vol 54, No 7, 1998,31-39. PM soft magnetic materials for automotive applications are reviewed and the demand for improvements in performance was noted. Effects of modified alloy composition and changes in process parameters on magnetic properties discussed are and investigations described. Results are presented and discussed relative to performance requirements. MAGNETIC PROPERTIES OF INJECTION MOULDED NEODYMIUMIRON-BORON MAGNETS O.Yamashita. (Sumitomo Special Metals Co Ltd, Osaka, Japan.) Int. J. Powder Metall., Vol 54, No 7, 1998, 41-50. An investigation of injection moulding of Nd-Fe-B powders, with a water soluble methyl cellulose binder, is described. Feedstock was mixed at 30°C injected at 20°C into a die heated to 80°C. A magnetic field was applied to align particles. Compacts were debound by vacuum de-hydration and thermally at 300°C in H. 80% of the binder C was removed but 0 remained. Magnetic properties of sintered bodies are described. PARTICLE BONDING DURING HEAT TREATMENT OF GREEN COMPACTS FOR SOFT MAGNETIC APPLICATIONS S.Pelletier et al. (National Research Council of Canada, Quebec, Canada.) Int. J. Powder Metall., Vol54, No 7,1998, 51-58. It is reported that heat treatment, at 175”C, of Fe base magnetic powders improves green strength of compacts. Effects of time, temperature and atmosphere on structure, transverse and rupture strength electrical investigated to resistivity were elucidate mechanisms that enhance inter-particle bonding. It is shown that 0 is important in bonding oxide films on and promoting particle surfaces increase in strength without lowering resistivity.
26 MPR July/August
2000
STRUCTURE AND PROPERTIES OF MECHANICALLY ALLOYED IRONSILICON-BORON-NIOBIUM-COPPER G.Principi et al. (University of Padova, Padova, Italy.) Int. J. Non-Equilibrium Process., Vol 10 No 314, 1998,283-296. Fe-Sat%Si-G%BNanocrystalline 3%Nb-l%Cu powders were prepared by and high energy ball milling characterized for structure and magnetic properties. A body-centred cubic Fe-(Si, Cu, Nb, B) disordered solid solution and a crystalline non-stoichiometric Fe-Si phase were detected. Powders subjected to long-time milling and annealing at 700°C contained Fe& small amounts of borides and Fe-Nb aggregates. ANISOTROPIC FORMING OF MAGNETIC POWDERS MIXED WITH ULTRA-VIOLET RESIN S.Toyota et al. (Sumitomo Special Metals Co Ltd, Osaka, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 46, No 1, 1999,83-87. (In Japanese.) Ferrite powder was mixed with UV resin, compacted and then aligned in a magnetic field. Effects of viscosity of the resin and forming conditions on magnetic properties of the compacts were investigated. Degree of alignment reached a maximum of 82.6%. It was desirable to have a resin with a low viscosity and which parts easily from the tooling. It is suggested that the method makes production of high performance magnets feasible. EFFECT OF PARTIAL PRESSURE OF OXYGEN ON GRAIN GROWTH IN MAGNESIUM-ZINC FERRITES ON HEATING T.Murase, T.Nomura. (TDK Corp, Narita, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 46, No 1, 1999, 9297. (In Japanese.) It is noted that excess Fe,O, causes discontinuous grain growth in MgZn ferrites. It is shown that firing in an atmosphere with low partial pressure of 0 suppresses this grain growth and leads to a uniform microstructure. NICKEL-COPPER-ZINC FERRITES SINTERED AT LOW TEMPERATURE WITHOUT SHRINKAGE SHarada et al. (Matsushita Electronic Component Co Ltd, Kadoma, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 46, No 1,1999,98-102. (In Japanese.)
It is noted that a non-shrinking ferrite can be produced by adding Fe and sintering at 1200°C. non-shrinking Investigations of ferrites, sintered at less than 96O”C, are described. In these, expansions caused by oxidation of Fe and reactions with NiO, CuO and ZnO result in no shrinkage but high density is not attained. Addition of low melting point oxides is reported to enable production of a uniform and compact structure which has a spine1 structure. The magnetic characteristics are similar to those of conventional low temperature sintered ferrites. PRODUCTION OF THERMO-ELECTRIC MATERIALS BY MECHANICAL ALLOYING OR MECHANICAL GRINDING S.Katsuyama. (Osaka University, Suita, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 46, No 3, 1999, 219-226. (In Japanese.) The thermo-electric properties of CoCoSb,-FeSb, Fe-Sb alloys and composites were investigated. Samples were prepared by mechanical alloying and mechanical grinding to prepare the composite. It is shown that as Fe progressively replaces Co the Seebeck effect, electrical resistivity and thermal conductivity are reduced. MAGNETICALLY SOFT MAGNETIC MATERIALS WITH HIGH WEAR RESISTANCE O.A.Panasyuk et al. Powder Metall. Metal Ceramics, Vol 36, No 1102, 1998, 604-608. The need for soft magnetic materials with high wear resistance for tape recorder heads is noted. It is reported that Fe-Si-Al alloys are used. Permalloy lacks the wear resistance for this application. This can be improved by additions of Nb, Zn, Ti, Ta or Sb or hard particles such as Al,O,. FeTi or NiTi form and improve friction properties by formation of a heterogeneous structure in the sintered materials. HIGH PERFORMANCE WATER ATOMIZED ALMCO POWDERS H.Koyama et al. Denki Seiko (Electric Furnace Steel), Vol 69, No 2, 1998, 131136. (In Japanese.) It is shown that by using water atomized Alnico powders, instead of cast and crushed powders, the magnetic
and magnetic
PM SOFT MAGNETIC MATERIALS FOR AUTOMOTIVE APPLICATIONS D.R.Ryan et al. (Windfall Products Inc, St. Mary’s, USA.) Int. J. Powder Metall., Vol 54, No 7, 1998,31-39. PM soft magnetic materials for automotive applications are reviewed and the demand for improvements in performance was noted. Effects of modified alloy composition and changes in process parameters on magnetic properties discussed are and investigations described. Results are presented and discussed relative to performance requirements. MAGNETIC PROPERTIES OF INJECTION MOULDED NEODYMIUMIRON-BORON MAGNETS O.Yamashita. (Sumitomo Special Metals Co Ltd, Osaka, Japan.) Int. J. Powder Metall., Vol 54, No 7, 1998, 41-50. An investigation of injection moulding of Nd-Fe-B powders, with a water soluble methyl cellulose binder, is described. Feedstock was mixed at 30°C injected at 20°C into a die heated to 80°C. A magnetic field was applied to align particles. Compacts were debound by vacuum de-hydration and thermally at 300°C in H. 80% of the binder C was removed but 0 remained. Magnetic properties of sintered bodies are described. PARTICLE BONDING DURING HEAT TREATMENT OF GREEN COMPACTS FOR SOFT MAGNETIC APPLICATIONS S.Pelletier et al. (National Research Council of Canada, Quebec, Canada.) Int. J. Powder Metall., Vol54, No 7,1998, 51-58. It is reported that heat treatment, at 175”C, of Fe base magnetic powders improves green strength of compacts. Effects of time, temperature and atmosphere on structure, transverse and rupture strength electrical investigated to resistivity were elucidate mechanisms that enhance inter-particle bonding. It is shown that 0 is important in bonding oxide films on and promoting particle surfaces increase in strength without lowering resistivity.
26 MPR July/August
2000
STRUCTURE AND PROPERTIES OF MECHANICALLY ALLOYED IRONSILICON-BORON-NIOBIUM-COPPER G.Principi et al. (University of Padova, Padova, Italy.) Int. J. Non-Equilibrium Process., Vol 10 No 314, 1998,283-296. Fe-Sat%Si-G%BNanocrystalline 3%Nb-l%Cu powders were prepared by and high energy ball milling characterized for structure and magnetic properties. A body-centred cubic Fe-(Si, Cu, Nb, B) disordered solid solution and a crystalline non-stoichiometric Fe-Si phase were detected. Powders subjected to long-time milling and annealing at 700°C contained Fe& small amounts of borides and Fe-Nb aggregates. ANISOTROPIC FORMING OF MAGNETIC POWDERS MIXED WITH ULTRA-VIOLET RESIN S.Toyota et al. (Sumitomo Special Metals Co Ltd, Osaka, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 46, No 1, 1999,83-87. (In Japanese.) Ferrite powder was mixed with UV resin, compacted and then aligned in a magnetic field. Effects of viscosity of the resin and forming conditions on magnetic properties of the compacts were investigated. Degree of alignment reached a maximum of 82.6%. It was desirable to have a resin with a low viscosity and which parts easily from the tooling. It is suggested that the method makes production of high performance magnets feasible. EFFECT OF PARTIAL PRESSURE OF OXYGEN ON GRAIN GROWTH IN MAGNESIUM-ZINC FERRITES ON HEATING T.Murase, T.Nomura. (TDK Corp, Narita, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 46, No 1, 1999, 9297. (In Japanese.) It is noted that excess Fe,O, causes discontinuous grain growth in MgZn ferrites. It is shown that firing in an atmosphere with low partial pressure of 0 suppresses this grain growth and leads to a uniform microstructure. NICKEL-COPPER-ZINC FERRITES SINTERED AT LOW TEMPERATURE WITHOUT SHRINKAGE SHarada et al. (Matsushita Electronic Component Co Ltd, Kadoma, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 46, No 1,1999,98-102. (In Japanese.)
It is noted that a non-shrinking ferrite can be produced by adding Fe and sintering at 1200°C. non-shrinking Investigations of ferrites, sintered at less than 96O”C, are described. In these, expansions caused by oxidation of Fe and reactions with NiO, CuO and ZnO result in no shrinkage but high density is not attained. Addition of low melting point oxides is reported to enable production of a uniform and compact structure which has a spine1 structure. The magnetic characteristics are similar to those of conventional low temperature sintered ferrites. PRODUCTION OF THERMO-ELECTRIC MATERIALS BY MECHANICAL ALLOYING OR MECHANICAL GRINDING S.Katsuyama. (Osaka University, Suita, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 46, No 3, 1999, 219-226. (In Japanese.) The thermo-electric properties of CoCoSb,-FeSb, Fe-Sb alloys and composites were investigated. Samples were prepared by mechanical alloying and mechanical grinding to prepare the composite. It is shown that as Fe progressively replaces Co the Seebeck effect, electrical resistivity and thermal conductivity are reduced. MAGNETICALLY SOFT MAGNETIC MATERIALS WITH HIGH WEAR RESISTANCE O.A.Panasyuk et al. Powder Metall. Metal Ceramics, Vol 36, No 1102, 1998, 604-608. The need for soft magnetic materials with high wear resistance for tape recorder heads is noted. It is reported that Fe-Si-Al alloys are used. Permalloy lacks the wear resistance for this application. This can be improved by additions of Nb, Zn, Ti, Ta or Sb or hard particles such as Al,O,. FeTi or NiTi form and improve friction properties by formation of a heterogeneous structure in the sintered materials. HIGH PERFORMANCE WATER ATOMIZED ALMCO POWDERS H.Koyama et al. Denki Seiko (Electric Furnace Steel), Vol 69, No 2, 1998, 131136. (In Japanese.) It is shown that by using water atomized Alnico powders, instead of cast and crushed powders, the magnetic