Preparation of Samarium Cobalt Permanent Magnet by Compacting with Solid Pressure Media

Abstract

A new modification of the preparing method of SmCo₅ permanent magnets is studied. The method involves compacting the field-oriented pellet of the alloy powder through a solid state pressure transmitting medium in a conventional axial pressing apparatus. Zinc and calcium stearates have proved to give very satisfactory results as pressure media up to 30 kbar. Permanent magnets with (B H)_max of 15 MGOe is obtained. It is found that an essential improvement of the particle alignment is achieved in the field-orienting process when the powder is pressed in the perpendicular, rather than parallel, direction to the magnetic field. Long term aging experiments of epoxy-bonded magnets are conducted and no change of B _r and ₁ H _c has been found in 15,000 hours at room temperature and 1,500 hours at 50°C.