THE INFLUENCE OF MANUFACTURING CONDITIONS ON MICROSTRUCTURE AND MAGNETIC PROPERTIES OF BaFe12O19 POWDERS

The aim of the paper was a trial of using mechanical alloying process of mixture iron oxide and barium carbonate to produce BaFe12O19 powders. The milling process was carried out in a vibratory mill for 10, 20 and 30 hours. The size distributions of powder particles showed that the size of tested particles increases with the increase of milling time indicating the agglomeration process of particles. The milling process of Fe2O3 and BaCO3 mixture for studied milling times causes decrease of the crystallite size of involved phases and leads to increase of Fe2O3 phase content and decrease of BaCO3 one. The milling process did not lead to formation of BaFe12O19 phase, thus it probably causes setting of Fe2O3 on surface layer of BaCO3 powder particles. The XRD investigations of Fe2O3 and BaCO3 mixture milled for 10, 20 and 30 hours and annealed at 1000 degrees C for 1 hour enabled the identification of hard magnetic BaFe12O19 phase. For applied magnetic field of 800 kA/m, the coercive force is equal to 343 kA/m, 358 kA/m and 366 kA/m whereas the remanence is equal to 0.118 T, 0.109 T and 0.127 T for the samples after milling for 10, 20 and 30 hours, respectively.