| 摘要 |
1,229,441. Iron oxide coating. STAMICABBON N.V. 28 June, 1968 [6 July, 1967; 23 Nov., 1967; 6 Jan., 1968], No. 31026/68. Heading C1A. [Also in Division H1] A coating of iron oxide, with or without other oxides, on a particulate non-magnetic carrier, is produced by suspending the carrier in an aqueous solution of a hydrolysable ferrous compound, and hydrolysing the solution at a controlled rate such that the iron oxide is precipitated on the carrier and has a particle size of 10-400 A. The supported carrier is then dried, optionally calcined, and used to coat a tape, sheet, wire, or record. Control of the hydrolysis may be effected by the presence of urea or urea derivatives in the solution. The carrier may be Si0 2 , A1 2 O 3 , TiO 2 , Cr 2 O 3 , MnO, ZnO, CdO, Al silicate, or graphite. It is preferably porous and has a particle size not greater than 200 A. The solution may optionally contain Co, Ni, Mn, Cu, Ti, Ba, Ca, Mg, Sr, Pb, Zn, Sn, Hg, and B, as chloride, sulphate, or nitrate. The separated particles may be dried at 100-150‹ C., and calcined at 200-850‹ C. (e.g. to homogenize the various layers) or reduced at 300‹ C. and reoxidized. In examples, SiO 2 was coated with Fe 2 O 3 (said to be #FeO(OH) and γ Fe 2 O 3 .H 2 O), Ni ferrite, and Co ferrite, A1 2 0 3 with Fe 2 O 3 , and SiO 2 -Al 2 O 3 with Fe 2 O 3 |
