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

Abstract

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.