Ferrite Magnets were first engineered by Philips, Netherland in late 50’s. They are made of 85% iron oxide plus oxides of Barium or Strontium Ferrites. They are mixed with a ceramic binder which are compressed and sintered. Dry-pressing results in isotropic magnets. Wet pressing results in anisotropic magnets which store far more energy. Ferrite magnets are the cheapest magnets. But they are lot weaker. They are very hard but brittle. They are resistant to water, salt, petrol, but not to acids. They are used in toys, speakers and motors. They suffer from low energy (1 to 5 MGOe) and low flux density (Br ~ 0.25 to 0.4 T). Their maximum service temperature is 350C.
PMAG Database DM lists 430 B(H) Demagnetization Curves of 134 grades, produced by 19 manufacturers worldwide. For names of all these grades, please click on PMAG, Materials.