Obtaining barium hexaferrite brand 7BI215 with improved isotropic properties

Autor: A. N. Nikolaev, V. G. Kostishin, E. I. Kislyakova, I. I. Kaneva, V. G. Andreev, D. N. Chitanov
Rok vydání: 2015
Předmět:
Zdroj: Russian Microelectronics. 44:517-522
ISSN: 1608-3415
1063-7397
Popis: Currently, the global production of permanent magnets is about 150000 tons per annum, in which the share of ceramic magnets made of barium and strontium hexaferrites is more than 90%. Anisotropic hexaferrites have outstanding magnetic properties; in these materials, the texture is formed by pressing in the magnetic field, i.e., the hexagonal axes of flaky powder particles are oriented in the direction of the magnetic field; thus, the magnetic properties in this direction increase and decrease in the other directions. However, in a great number of applications, cheaper isotropic magnets, which have inferior magnetic properties, are successfully used; in these magnets, the magnetic axes of the particles are distributed uniformly in all directions, so magnetic properties are the same in all directions. The well-known technologies for fabricating isotropic magnets do not provide sufficient isotropy of magnetic properties, since the texture, which is due to the orientation of flaky hexaferrite particles, is formed in the process of pressing, which, in turn, reduces the magnetic energy of ring magnets in the radial direction. In this paper, we investigate the possibility of obtaining barium hexaferrite with isotropic properties by using a short manufacturing scheme, which includes no operations of diffusion annealing and grinding. It is shown that such a manufacturing scheme, which involves pressing the mixture (granulated with a binder) of the initial components with the near-spherical shape of particles, makes it possible to improve the isotropic properties of the magnet.
Databáze: OpenAIRE
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