Process for the preparation of permanently magnetizable mixed oxides containing iron

Abstract

Abstract A PROCESS FOR THE PREPARATION OF PEMANENTLY MAGNETIZABLE IRON CONTAINING MIXED OXIDES BY PRECPITATION FROM AN AQUEOUS SOLUTION IS DISCLOSED. AN AQUEOUS SOLUTION OF A FERROUS SALT CONTAINING ALSO ONE OR MORE SALTS OF OTHER METALS, BUT NO OXIDIZING AGENTS, IS INTENSIVELY STIRRED, WHEREBY A PRECIPITATE IS GRADUALLY FORMNED AT ELEVATED TEMPERATURE BY HYDROLIZING UREA, LKIEWISE PRESENT IN THE SOLUTION, TO AMMONIUM CARBAMATE, OR AMMONIUM CARBONATE, AND THE PRECIPITATE SO FORMED IS SUBSEQUENTLY SEPARATED FROM THE LIQUID, WASHED, DRIED AND IF NECESSARY, HEAT-TREATED IN CONTACT WITH AIR. PREFERABLY THE PRECIPITATION IS CARRIED OUT IN AN INERT ATMOSPHERE. IF THE PRECIPITATE IS USED FOR THE PREPARATION OF A PERMANENTLY MAGNETIZABLE MIXED OXIDE TO BE USED ON TAPES OR SHEETS, THE MATERIAL IS SUBJECTED TO A TERMAL TREATMENT BELOW 500*C., AND FOR THE PREPARATION OF MOULDED OBJECTS, THE COMPRESSED MATERIAL IS SUBJECTED TO A THERMAL TREATMENT AT TEMPERATURES OF 1000*C. OR OVER.

Inventors

• 👤 John W Geus

Bibliographic Details