A feasible approach for preparing remanence enhanced NdFeB based permanent magnetic compositesThe magnetocrystalline anisotropy of several intermetallic phases of the type RC06 (R= Y, Ce, Pr, Sm, Yorich and Ce-rich mischmetals) has been investigated, and it is concluded that these alloys are promising candidates for fine-particle permanent magnets. They have extremely high uniaxial anisotropy (K = 5.4 to 7.7 X 10 7 erg/cm 3 ), single easy axis, high saturation (B, = 8500 to 11 200 G) and Curie point (l c =464° to 747°C). Approximate upper limits for the possible energy product lie between 18 and 31.3 MGOe. Experimentally, coercive forces of over 8000 Oe and (BH) max = 5.1 MGOe have been observed in SmC06 merely ground at room temperature. Grinding of YCo. and (Ce-MM) C0 6 produces an increase of MHc to 2200 and 2700 Oe, respectively, followed by a decrease as particle size continues to decrease.

No abstract

No abstract

Permanent magnets (PMs) are vital components of many electromechanical machines and electronic devices, but they are usually hidden in subassemblies. System designers and end users often give no thought to how choice and use of the permanent magnet material affect performance, size, and cost of the product. This paper describes the range of materials and properties now at the disposal of design engineers and the place of different magnets in electro-technology, with attention to engineering and economic aspects.Revolutionary developments have recently occurred in the old field of permanent magnetism. Hard ferrites became an abundant inexpensive magnet material while the rare-earth magnets raised the highest available energy products 4 to 5-fold and coercivity by an order of magnitude. As a consequence, a rapid broadening of magnet uses is now occurring; traditional devices are miniaturized, new applications and design concepts are evolving. Trends and examples are discussed in this paper. A confluence of recent developments in magnets, power semiconductors and microprocessors is particularly fruitful in the area of drives and motion control. We also assess currently evolving permanent magnet materials. production processes, prospects for new, still "better" magnets, as well as ultimate upper limits for permanent magnet properties.

No abstract