Effects of technological factors upon the properties of permanent magnets made from very fine iron powder

Conclusions

• 1. By producing permanent magnets from a very fine iron powder, it is possible to dispense with the use of expensive and scarce metals such as cobalt, nickel, and copper.

• 2. Experiments have shown that a powder dried, with continual mixing, in thin layers exposed to a current of air ensures improved magnetic properties.

• 3. The addition of binder to a wet, washed powder results in a more uniform binder distribution. The presence of a protective binder film on the surfaces of particles reduces the oxidation of the powder and improves the properties of permanent magnet specimens produced from it.

• 4. Magnets of improved magnetic properties — higher induction, coercive force, and (BH)_max value — can be produced from a powder subjected to hydrogen reduction.

• 5. It is shown that pressing in a magnetic field perpendicular to the direction of the pressing force has the most marked beneficial effect upon the properties of the resultant permanent magnets. The presence of such a field evidently enables the required texture to be preserved during the pressing operation.