| 摘要 |
PURPOSE:To produce extremely fine magnetic metallic powder by sticking the water soluble salt of a specific metal and water soluble boric acid compd., etc. onto the surface of the oxide and hydrated oxide of Fe contg. Ni, Co, etc. and reducing the same by a reducing gas. CONSTITUTION:The powder of the spindle type goethite which is obtd. by blowing an oxidative gas to a liquid mixture composed of an aq. ferrous salt soln. of Fe contg. Ni and Co and aq. alkali carbonate soln. to oxidize the same and has 0.05-0.3mum long axis diameter and 3-15 axial ratio or the iron oxide obtd. by dehydrating such goethite is dispersed in an aq. soln. for dissolving the water soluble salt such as nitrate, hydrochloride or sulfate of Al, Cr, Ce, Cd, etc. An aq. soln. of acetate, nitrate, etc. of IIa group elements such as Mg, Ca, Sr and B is added into such dispersion and further the aq. soln. of the water soluble boric acid compd. or perboric acid compd. is added thereto. The cake obtd. by filtering the produced suspension is dried and is then reduced by gaseous H2 in a fixed bed type tubular reduction furnace. The ultrafine powder metal as a magnetic recording medium such as magnetic tape or magnetic disk is obtd. |
