Evaporation material and method of preparing the same

Details Evaporation material and method of preparing the same Evaporation material and method of preparing the same

1994-01-04

1995-08-15

Chaudhuri, Olik

Single-crystal, oriented-crystal, and epitaxy growth processes;

Processes of growth from liquid or supercritical state

Having moving solid-liquid-solid region

117900, 427422, 427456, C30B 2900

Patent

active

054410100

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to an evaporation material of a cobalt-nickel (Co--Ni) group alloy or a cobalt (Co) metal which is employed in a process of manufacturing an evaporated videotape or the like, or an evaporation material of a cobalt-chromium (Co--Cr) group alloy which is employed in a process of manufacturing a vertical magnetic recording thin film or the like, and a method of preparing the same.


BACKGROUND OF THE INVENTION

Recently, recording of higher picture quality and higher tone quality is required for a videotape. In order to cope with this, a tape is now being employed on which is evaporated a Co metal or a Co--Ni alloy capable of recording and having higher magnetic density as compared with a conventional tape coated with ferrite or a metal. The Co metal or the Co--Ni alloy is excellent in magnetic properties, i.e., coercive force and residual magnetic flux density. Therefore, recording of high picture quality and high tone quality is enabled by improving the magnetic density in a tape on which a Co metal or a Co--Ni alloy is evaporated. Further, future demand increase is expected for such an evaporated tape in relation to long-time recording, application to high-definition broadcasting and the like.
With reference to FIG. 2, an evaporation step for such a tape is described. FIG. 2 is a schematic diagram showing an evaporation unit A delivery shaft 13, a take-up shaft 14, a crucible 16, an electron gun 17 and a feeder 18 are arranged in the interior of a vacuum chamber 11. The delivery shaft 13 delivers a base film (polyester film, for example) 12, and the take-up shaft 14 takes up the evaporated base film 12. The crucible 16 stores an evaporation material 15. The evaporation material 15 is heated, melted and vaporized by an electron beam which is emitted from the electron gun 17. The evaporation material 15 is fed from the feeder 18 to the crucible 16. In such a unit, the interior of the vacuum chamber 11 is held in a vacuum state of about 10.sup.-5 to 10.sup.-6 Torr, and thereafter the evaporation material 15 is heated by the electron beam to a temperature of about 2000.degree. C., to be melted and vaporized. The vaporized evaporation material 15 reaches an upper portion the base film 12. Thus, a thin film is formed on the base film 12 by evaporation.
A Co--Cr group alloy is also excellent in magnetic properties, i.e., coercive force and residual magnetic flux density. Therefore, the Co--Cr group alloy is employed as a material for a vertical magnetic recording thin film in recent years. This material is formed and employed as a vertical magnetic film by evaporation.
An evaporation method therefor is carried out in the interior of a vacuum chamber which is held in a vacuum state of about 10.sup.-5 to 10.sup.-6 Torr. An evaporation material stored in a crucible is heated by an electron beam to a temperature of about 2000.degree. C., to be melted and vaporized. The vaporized material is made to reach a surface of a substrate, so that a thin film is formed on the surface of the substrate by evaporation.
It is necessary to refill the evaporation material of a Co metal, a Co--Ni alloy or a Co--Cr alloy for the vaporized part. Such refilling is carried out through a pellet member of about 10 mm.phi. by 10 to 30 mm in size or a bar member of 30 to 80 mm.phi.. In general, a pellet member is dropped into a molten metal which is contained in a crucible, while a bar member is partially melted and dropped into a molten metal for refilling.
A method of manufacturing a pellet member is now described. First, a material such as a Co--Ni alloy is vacuum-fused, cast, hot-forged, and rolled to prepare a rolled wire. Then, this rolled wire is inserted in a hole of a die assembly as shown in FIG. 33, and a wire 9 which is projected from an opening portion of the hole is cut by shearing of a die A and another die B. Then, the as-obtained short member is subjected to barrel polishing and surface cleaning with an organic solvent, to obtain a pellet.
According to the aforementioned

REFERENCES:
patent: 3091022 (1963-05-01), Faulkner

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