PREPARATION OF MAGNETIC GRAIN POWDER CONSISTING OF NEEDLE CRYSTAL ALLOY OF IRON AND COBALT

摘要

PURPOSE:To obtain the magnetic grain powder consisting of needle crystal alloy of iron and cobalt with superior magnetic and powder characteristics by using materials consisting of the needle crystal goethite grain containing cobalt produced in the region of specific relation between silicon and cobalt by means of a specific procedure and applying heat burning and reduction to the materials under specific conditions. CONSTITUTION:Water soluble silicic salt should by previously added to the alkali solution which is to be used to obtain the solution containing Fe(OH)2 and Co(OH)2 in a fixed ratio and indicating pH12 so that silicon occupies 0.1-1.1atom% against the whole metallic atom (cobalt) [provided that the range of the quantity of addition of Co(OH)2 and slicic salt should be defined separately] and, after reacting the alkali solution mentioned above with ferrous salt and so on, the mixture is oxidized to produce the needle crystal goethite grain containing coba after heating and dehydrating materials obtained from the produced grains, needle crystal hematite grains with cobalt, which have a fixed longitudinal axis length and a fixed axial ratio, are produced, burned by heating under a specific steam partial pressure consisting of heating steam and non-reduction gas and a specific temperature and reduced while heating at a specific temperature to obtain the magnetic grain powder consisting of needle crystal alloy of iron and cobalt with a specific average longitudinal aixs length and a specific surface area.