| 摘要 |
A method of depositing a film of ferromagnetic metal on a substrate (e.g. a tape) comprises heating a ferromagnetic metal in a vacuum so as to evaporate the metal, directing and condensing the evaporated metal on to a substrate to form a first ferromagnetic metal layer, cooling the first metal layer to room temperature, heating further ferromagnetic metal in a vacuum to evaporate the further metal, directing and condensing the evaporated further metal on to the first metal layer at an angle of incidence greater than 45 DEG to form a second ferromagnetic metal layer, and cooling the second metal layer to room temperature. The first and second layers may each be deposited in a series of bursts so as to increase coercivity of the film. Ferromagnetic metals which may be used are Co, Fe, Ni, Co-Fe, Co-Ni or Ni-Fe containing between 1 and 74 or 86 and 99% by weight Ni and the balance Fe. To modify the magnetic properties between 0.5 and 4.0% by weight S may be evaporated simultaneously with the metal. In the examples the substrate is of polyethylene terephthalate. The metal forming the first metal layer may be directed on to the substrate at an angle of incidence greater than 45 DEG , the first metal layer may then be cooled to at most 60 DEG in a non-oxidizing atmosphere and thereafter cooled to room temperature in an oxidizing atmosphere. Alternatively, the first metal may be directed on to the substrate at normal incidence. Where an isotropic magnetic film is to be produced, the first metal layer is cooled in an oxidizing atmosphere from a temperature greater than 150 DEG C. This produces a partially oxidized film. Where an anisotropic film is to be produced, the first metal layer is cooled in a non-oxidizing atmosphere to below 60 DEG C. prior to exposure to an oxidizing atmosphere. The apparatus in which the method is carried out may be the same as that disclosed in Specification 1,104,708. Fig.2 (not shown) illustrates apparatus for continuously producing magnetic tape. It comprises in sequence a vacuum evaporation chamber (70), a cooling chamber (74), a vacuum evaporation chamber (72) and a cooling chamber (76). The Specification recites claim 1 of Specification 1,104,709. |
