IMPROVEMENT OF CERAMIC METHOD FOR SYNTHESIZING M-TYPE HEXAFERRITES

The aim of this paper is to improve the standard ceramic method for th e synthesis of hexaferrites, studying several alternatives to the usua l raw materials of iron and barium oxides and new ways of developing t he wet-milling. The research has been focused in the two first stages (the so-called red-milling and the presintering or calcination step) o f this process, optimizing their variables. They are type of milling-f luid, temperature and time of calcination, heating rate and BaO/Fe2O3 molar ratio. The optimization variable was the coercive field. The use of iron oxides different than alpha-Fe2O3 yields hexaferrites with ma gnetic properties higher than commercial ones. Thus, these hexaferrite s are optimum as permanent magnets and can replace other more expensiv e magnets.