Patent ID: 9601247
Date: 2017-03-21
CPC Classifications: C01G,C01P,C04B,H01F

Claim:
1. A method for producing a sintered ferrite magnet comprising main phases of ferrite having a hexagonal M-type magnetoplumbite structure, first grain boundary phases existing between two main phases, and second grain boundary phases existing among three or more main phases; said second grain boundary phases being dispersed in an arbitrary cross section of said sintered ferrite magnet; and said second grain boundary phases having an average area of less than 0.2 μm 2 ; said method comprising the steps of preparing raw material powders comprising metal elements of Ca, La, an element A which is Ba and/or Sr, Fe and Co, which are represented by the general formula of Ca 0.3≦1−x−y≦0.65, 0.3≦x≦0.65, 0≦y≦0.2, 0.25≦z≦0.65, and 4.5≦n≦7; calcining said raw material powders to obtain a calcined body; pulverizing said calcined body to powder; molding said powder to obtain a green body; and sintering said green body to obtain a sintered body; 0-1.8% by mass of SiO said sintering step being conducted with a temperature-elevating speed of 1-4° C./minute in a temperature range from 1100° C. to a sintering temperature, and a temperature-lowering speed of 6° C./minute or more in a temperature range from the sintering temperature to 1100° C.