| 摘要 |
1,137,288. Magnetic data-storage apparatus. INTERNATIONAL BUSINESS MACHINES CORP. 10 Nov., 1966 [23 Dec.; 1965], No. 50346/66. Heading H3B. [Also in Divisions D1 and H1] A storage device is produced by forming a layer of green magnetic ferrite around a cylindrical substrate, surrounding this layer with a green non-magnetic ferrite, slicing both ferrites, and sintering the slices. The magnetic ferrite may be Fe 1 . 62 Mn 0 . 80 Cu 0 . 45 Zn 0 . 10 Bi 0 . 02 La 0 . 01 O 4 and may be prepared by ball-milling a mixture of Fe, Cu, Zn and Bi oxides, MnCO 3 , and LaFeO 3 , passing it through a 20-mesh screen, calcining at 650‹ C., remilling, passing it through a 325-mesh screen, and drying. The non-magnetic ferrite may be Fe 1 . 2 Mn 0 . 78 Cu 0 . 3 Zn 0 . 7 Bi 0 . 02 0 4 or Fe 0 . 8 Mn 1 . 48 Cu 0 . 2 Zn 0 . 5 Bi 0 . 02 O 4 . A barrier layer, e.g. of Mn 3 O 4 , Cr 2 O 3 , Mn 3 O 4 + Cr 2 O 3 or Mn 3 O 4 +ZnO, may be provided between the two ferrites. The substrate may be a nylon filament which may be coated with a release agent, e.g. colloidal wax in water, and removed by pulling from one end. The magnetic and barrier layers may be applied by passing a continuous length of the filament through a suspension of the material and then passing it twice through an oven (at 70‹ and 80‹ C., using a nitrocellulose-amyl acetate solution, and at 100‹ and 110‹ C., using an epoxy resin solution); this process is repeated five times and the filament is then passed through an oven (at 85‹ or 125‹ C. resp.) 10 times. The structure may then be similarly coated with the non- magnetic ferrite, and a number of such structures cast in a wax or polyethylene block; the filament is then removed, the block sliced, and the wax melted off by heating to 100- 125‹ C. Alternatively, the structures may be cast in a block of the non-magnetic ferrite, which is dried at 90‹ C. in the mould and then at 100‹ C.; the filament is removed; and the block is then sliced either perpendicular to or along the axes of the cores (in the latter case the two halves are turned through 90 degrees before firing). Firing may be effected in a Ni boat coated with Mn 3 O 4 , initially at 600‹ C. to drive off the binder, and then at 920‹ C. The magnetic layer may have an inner diameter of 3 or 4À5 mils. |
