Extrusion of strontium hexaferrite magnets with radial alignment using hydrothermally synthesized powder

Summary form only given The hydrothermally synthesized strontium hexaferrite (HT-SrM) powder was used to produce EVA-paraffin wax system pastes for extrusion of SrM sintered magnets. The rheological properties have been studied using capillary rheometer and optimal pastes were obtained. Using such pastes, radial magnetic alignment in ring extrudates was induced by paste flow only. VSM results shows clearly a strong magnetic anisotropy in a SrM ring magnet extruded at 55/spl deg/C. SEM and XRD results are in agreement with the VSM results. The effects of polymer content, extrusion temperature, and sintering temperature on the orientation of ferrite particles have been investigated. Due to the very high specific surface area of the plate-like HT-SrM particles, the maximum solid phase load could not exceed 47 vol% for the powder mixed even at 120/spl deg/C. The highest density of the sintered SrM magnets was 91% of theoretical density.