| 摘要 |
PURPOSE:When particles of iron oxyhydtroxide is precipitated from an aqueous solution of iron ion, a specific amount of a compound of an element in the group II of the periodic table is coprecipitated, thus producing fine and strong magnetic particles of iron compound that is free from particle destruction. CONSTITUTION:A fine powder of a group II element or its inorganic salt is added, in the form of aqueous solution, to an aqueous solution of ferrous or ferric salt at an atomic weight ratio of 0.001/100-10/100. An alkali aqueous solution is poured to the resulting solution to form an inert substance, which is oxidized by air to form fine needles of iron oxyhydroxide. These particles are washed with water, filtered, dried and pulverized or granulated. The resultant particles are reduced under heating to form a powder of Fe3O4 particles. Subsequently, the particles is subjected to catalytic oxidation to give a gamma-Fe2O3 particle powder. This process can keep the shape of fine needles of iron oxyhydroxide and gives iron compound particles fo r magnetic recording with freeness from particle destruction and good magnetic characteristics. |
