| abstract |
A METHOD OF PREPARING POWDERS HAVING IMPROVED MAGNETIC PROPERTIES FOR USE IN THE MANUFACTURE OF RECORDING TAPES IS SHOWN. A COLLOIDAL SUSPENSION OF IRON OXIDE IS FORMED. A SOLUTION OF A SALT OF COBALT AND/OR NICKEL IS ADDED TO THE COLLOIDAL SUSPENSION AND THE MIXTURE IS AGITATED AND THE PH THEREOF CONTROLLED TO FACILITATE ABSORPTION OF THE COBALT AND/OR NICKEL SALTS ON THE IRON OXIDE. THE IRON OXIDE IS THEN REMOVED FROM SUSPENSION, WASHED, DRIED AND GROUND AND THEN DEHYDRATED TO UNIFORMLY DIFFUSE THE COBALT OR NICKEL INTO THE IRON OXIDE. THE MASS IS THEN REDUCED TO FORM THE METALLIC ALLOY. THE POWDERS FORMED ACCORDING TO THE INVENTION HAVE SUBSTANTIALLY INCREASED VALUES OF COERCIVE FORCE AND MAGNETIZATION AND ARE PARTICULARLY SUITED FOR USE IN MASTER VIDEO TAPES. |