Abstract
In order to develop high coercivity strontium ferrite magnets having high magnetic energy product, simultaneous additions of SiO2 and Na2O have been studied.
The results obtained are as follows:
(1) Both addition of SiO2 and Na2O improves coercive force greatly without deterioration of Br and (BH)max more than by the addition of SiO2 only.
(2) Optimum amounts of addition are 0.25∼0.30wt% for SiO2 and 0.20∼0.25wt% for Na2O respectively.
(3) Magnetic properties, Br 4020G, BHC 3320Oe, (BH)max 3.9MGOe were obtained by addition of above range of SiO2 and Na2O.
(4) Grain growth inhibition was obtained by addition of SiO2 and Na2O. Fine grain microstructures were observed in the magnets. It is proposed to be caused by segregation of Si and Na at grain boundary.
