焼結磁石の製造プロセスにおける配向評価技術の開発

概要

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Degree of preferred orientation was evaluated at three stages in manufacturing sintered magnets such as Nd-Fe-B and Sr-ferrite. In magnetization stage, magnetization curves of raw powder were measured by vibration sample magnetometer, which suggested that rotation of particle started after technical magnetic saturation of the particle has completed. A rod-like structure with a diameter of few hundreds of microns was formed along the direction of applied field in case of Nd-Fe-B powder. In consolidation stage, the homogeneity of compaction was investigated visually by means of marker layers set parallel to the direction of applied field. The alignment was disordered locally in the vicinity of dies. Alternate movement of upper punch and lower one was effective to eliminate the disorder. As for sintering stage, degree of preferred orientation was evaluated quantitatively from data of X-ray pole figure measured not only for sintered samples but also for green compacts. Degree of preferred orientation of green compacts always increased after sintering, presumably because small and incompletely oriented particles were absorbed to larger and correctly oriented ones as a result of the grain growth in the sintering stage.
社団法人粉体粉末冶金協会の論文
2006-03-15