抄録
The magnetic product with different alignment of the crystallites produced by conventional magnetic alignment pressing is restricted in shape and size. This paper presents two methods to solve this problem. Both methods used a compound of Sr-ferrite powder mixed with a MIM binder. One method was the combined sinter joining of a disk and ring. The inner disk was compacted under a magnetic field and the ring was compacted under a non-magnetic field. In this method, a different mixing ratio of the same kind of MIM binder was used for the disk and the ring. The two compacts were assembled into a unit and then sintered at 1225°C after debinding. The other method was a two-step integration forming process. The MIM binders used in this method were different than that used in the combined sinter joining. As the first step, the inner disk was compacted under a magnetic field using a compound of a high-melting-point MIM binder. As the second step, the compound was mixed with a low-melting-point MIM binder and then poured into the circumference of the inner disk compact under a non-magnetic field to complete the integration. The integrated compact was debinded and then sintered at 1225°C. The joint strength between the orientated and non-orientated parts and also the magnetic characteristics of the orientated part of the sintered Sr-ferrite were investigated for both methods. The joint strength of the sintered Sr-ferrite compact obtained by the two-step integration forming process was superior to that obtained by the sinter joining. The maximum joint strength obtained by the two-step integration forming process was 20.2 MPa.
