PROCESS FOR PRODUCING COBALT CONTAINING FERROMAGNETIC IRON OXID

摘要

Magnetic iron oxide particles having a coating of particles of a cobalt compound or a cobalt- and iron-compound, are produced by precipitating a cobalt- and iron-bydroxide on to particles; and then heating. The heating of the coated particles is performed at 60-300≦̸C, expecially 80-150≦̸C in the presence of steam having a partial pressure of at least 20.3 KPa. The particles heated in a steam- containing atmosphere are also heated in an inert gas at 100-300 pref. 100-250≦̸C.