Sintered ferrite magnets

Barium and strontium ferrites, in terms of hardness and brittleness, are akin to a ceramic material. They consist of approximately 90% iron oxide (Fe2O3) and about 10% alkaline earth oxide (BaO or SrO). Oxide ceramic is relatively resistant to moisture, solvents, alkalis, weak acids, salts, lubricants and harmful gases. They are shaped by wet or dry pressing, isotropically or in a magnetic field with anisotropic magnets. This gives the magnet a preferred direction and thus achieves a significant improvement in remanence. Smaller magnet geometries are usually produced by dry pressing. To increase the surface density, ferrite ring magnets can be aligned polar anisotropically in the tool.