The paper shows the efficiency of application of magneto-fluidized bed formed of ferromagnetic materials in press-forms dosed filling and milling devices. For powders without natural fluidity, dosing device is situated between electromagnets creating constant magnetic field with horizontal induction lines and alternating gradient magnetic field with vertical induction lines and higher induction gradient in the lowest part of chamber with powder. This configuration allows development of uniform efflux speed of ferromagnetic powders from 2 mm diameter opening. For example, mass efflux speed of strontium ferrite powder with 1 µm average particle size in magneto-fluidized bed reached 181.1 mg/s and the dosing time of 2000 mg of this powder was 11.1 s. For practical usage of magneto-fluidized bed in the milling device, beater mill is situated between electromagnet poles in the way that induction lines of constant and alternating gradient magnetic fields were mutually perpendicular and parallel to the plane of rotating beaters. Milling of particulate strontium ferrite with 1558.5 µm average particle size during 120 minutes in magneto-fluidized bed allows increasing milling degree in 16.2 times by comparison with processing without electromagnetic effect.

The paper experimentally proves the efficiency of electromagnetic effect on stimulated fluidity of magneto-hard powders. Fine Nd-Fe-B powder doesn’t have natural fluidity. To make it flow through hopper outlet we effected on the powder by constant and alternating gradient magnetic fields. Induction lines of constant magnetic field were horizontal, and alternating field lines were vertical. In order to form stimulated powder fluidity, higher induction gradient was situated below the powder receiver chamber. We experimentally found optimal magnetic fields parameters that form steady magneto fluidized bed from Nd-Fe-B powder, with an average particle size 1 μm. The study results of influence of magneto fluidized bed electromagnetic parameters on Ne-Fe-B powder efflux speed through outlets with diameters 1 and 2 mm are presented. Gradient field topology and parameters of electromagnetic effect providing minimal efflux time of 1000 mg of powder are defined.

The paper presents the result of experimental studies of strontium hexaferrite milling in beater mill. SEM studies showed that milling of strontium hexaferrite in beater mill with formation of magneto fluidized bed leads to significant intensification of the process. Williamson-Hall method was used to determine structural characteristics changes in the strontium hexaferrite powder from milling time in magneto fluidized bed. Carried out studies showed that milling intensification is significant only to a certain dispersity of processed powder. However, during milling with formation of magneto fluidized bed, decrease of particle sizes and structural characteristics changes speed happens at finer disperse compound.

The paper experimentally substantiates effectiveness of method of milling particulate ferromagnetic materials in magneto fluidized bed. Comparative results of particle size distributions and structural parameters of strontium hexaferrite SrFe12O19 powder obtained by milling coarse material in beater mill without electromagnetic effect and in same mill with formation of magneto fluidized bed from mill material are presented. The magneto fluidized bed is formed by constant and alternating gradient magnetic fields with induction lines that are mutually perpendicular and parallel to the plane of rotating beaters. It is shown that application of electromagnetic effect to milling coarse material in beater mill allowed to greatly intensify that process, significantly increase powder quality: increase particle size distribution uniformity and decrease average particle size from 1558.50 μm to 0.56 μm after 120 minutes of processing in the mill. X-ray diffraction analysis showed that milling in beater mill in magneto fluidized bed leads to reduction of coherent-scattering region size, increase of lattice microstrain and dislocation density, making powder more active during sintering process.

The paper presents result of experimental studies of ferromagnetic powders fluidity management by effecting on particulate medium with constant and alternating gradient magnetic fields. Induction lines of constant magnetic field are perpendicular to symmetry axis of powder hopper. Alternating field is created by electromagnet with one tapering pole and has higher induction gradient values near hopper outlet. These fields form magneto fluidized bed from powder in hopper allowing powders of barium and strontium hexaferrite to flow through the hopper outlet. Dependencies of efflux speed from parameters of electromagnetic fields are presented for barium hexaferrite powder with average particle size 1 μm and strontium hexaferrite powders with average particle sizes 1 and 9 μm.