| 摘要 |
PURPOSE:To obtain the magnetic grain powder consisting of needle crystal alloy of iron, cobalt and zinc which has superior magnetic and powder charactersitics and is suitable especially for magnetic materials for magnetic recording by using materials consisting of the needle crystal goethite grain containing specific cobalt and zinc, which are produced by the specific procedures, and applying heating and reduction to them under specific conditions. CONSTITUTION:Water-soluble silicic salt should be previously added to the alkali solution which is to be used to obtain the solution containing Fe(OH)2, Co(OH)2 and Zn(OH)2 in a fixed ratio and indicating pH12 so that silicon occupies 0.1-0.7atom% against the whole metallic atoms (Fe, Co and Zn) and, after reacting the alkali solution mentioned above with ferrous salt and so on, the mixture is oxidized to produce the needle crystal grain containing goethite cobalt and zinc; after heating and dehydrating materials obtained from the produced grains, needle crystal hematite grains with cobalt and zinc, 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 nonreduction 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, cobalt and zinc with a specific average longitudinal axis length and a specific surface area. |
