METHOD OF PRODUCTION OF FINELY-DISPERSED FERRITE POWDER Russian patent published in 2003 - IPC

FIELD: manufacture of magnetoconducting articles in various industries. SUBSTANCE: proposed method includes mechanical dispersion of ferrite material, stirring mixture of polydispersed ferrite powder with chemically inert liquid till suspension is formed. Settling part of suspension is acted on by ultrasonic oscillations in reservoir made from non-magnetic material and finely-dispersed fraction of powder is separated. Density of flux of ultrasonic oscillation power is selected within range of 1.1-1.5 of density of power flux corresponding to cavitation threshold for suspension being treated ; height of suspension column is selected within range (0,4-2,0)/α, where α is attenuation coefficient of ultrasonic oscillations in suspension. For separation of finely-dispersed fraction of ferrite powder, use is made of upper layer of suspension at depth not exceeding one fourth of length of wave of ultrasonic oscillations in suspension. Suspension may be additionally acted on by heterogeneous permanent or variable magnetic field whose intensity gradient is opposite to Earth magnetic field. EFFECT: increased yield of finely-dispersed fraction of ferrite powder. 5 cl, 4 dwg, 1 tbl