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Method for preparing sintered permanent magnet ferrite magnets
Feb 08, 2019

The preparation of the sintered ferrite magnet requires several steps of batching, calcination, coarse pulverization, ball milling, molding and sintering. When the ingredients are prepared, the calcium carbonate powder, strontium carbonate powder, strontium carbonate powder containing the desired elements are weighed and weighed. The cerium oxide powder and the iron oxide powder are uniformly mixed by a wet process, and the mixed mixture has an average particle size of about 1.0 μm, and then the slurry is pumped into a centrifugal dehydrator for dehydration, and the slurry concentration after dehydration is 60-65%;


The dehydrated mixed slurry is pumped into the internal heating rotary kiln for pre-sintering, and the pre-firing temperature is 1250-1350 ° C for 5-6 hours to obtain pre-sintered particles; the pre-sintered particles are sent into the tube. The mill was subjected to dry ball milling to an average particle size of 3 - 5 μm to obtain a pre-fired powder.


Weigh the above-mentioned pre-calcined powder, add the secondary additive by weight ratio, and continuously grind the mixture by wet ball milling until the average particle size of the particles reaches 0.9-1.0 μm; after ball milling, naturally cool down, wait for the slurry The temperature reaches 50 ° C or less, the water content of the molding slurry is adjusted, adjusted to a slurry concentration of 60-65% by weight, and then magnetic field forming, the forming magnetic field strength is not less than 500 kA / m;


The obtained shaped body is first heat-treated at a temperature of 100-300 ° C to remove moisture, and then sintered in air, wherein the heating rate is 120-130 ° C / hour, the sintering temperature is 1150 - 1250 ° C, and the holding time is 1 ‐2 hours to obtain a high-performance sintered permanent magnet ferrite magnets.




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