Toda Kogyo Corporation

Yamaguchi Technology Licensing Organization, Ltd.

Shinko Industries Co., Ltd.

Mitsuru Matsuura

Setsuo Yamamoto

Yasuo Kakihara

Takanori Doi

Kousaku Tamari

Kenichi Nakata

Teruaki Santoki

Hiroki Kurisu

Atsushi Takemura

Masaki Hesaka

The objective of the present invention is to provide a titanium alloy vacuum container and vacuum parts that can easily achieve an ultra-high vacuum in a short time through vacuum evacuation. The titanium alloy of the titanium alloy vacuum container and vacuum parts has a compact structure composed of fine grains, each having a size of approximately not more than 10 &#x3bc;m, with a surface that is exposed to at least vacuum being set to have a surface roughness of not more than 50 nm; and in this structure, preferably, the surface roughness thereof may be set to not more than 10 nm, the titanium alloy may have a hardness in a range of not less than 230 Hv to not more than 310 Hv, and the titanium alloy may have a passivity surface film made by a thin titanium oxide layer or nitride layer that is formed on the surface thereof. The titanium alloy, which is desirably used in such titanium alloy vacuum container and vacuum parts, contains 0.3 wt. % to 0.5 wt. % of iron and 0.3 wt. % to 0.5 wt. % of oxygen, and the remainder thereof is made from Ti obligatory impurities.

Titanium alloy vacuum and vacuum part

A magnetic recording medium, comprises a substrate; and a Co-containing spinel-type iron oxide thin film formed on the substrate, having a Co content of 1 to 20 mol % based on Fe, a coercive force value of not less than 159 kA/m (2,000 Oe), a thickness of 5 to 200 nm, a center line average height Ra of 0.1 to 0.8 nm and a maximum height (Rmax) of not more than 10 nm. The magnetic recording medium is capable of exhibiting a relatively high coercive force, especially a coercive force of not less than 159 kA/m (2,000 Oe) despite as small a film thickness as not more than 200 nm, and an excellent surface smoothness.

Magnetic recording medium and process for producing the same

A magnetic recording medium is prepared by forming on a plastic substrate, a nickel oxide underlayer having a plane (200) which is predominantly oriented in parallel with the surface of the plastic substrate, then forming on the nickel oxide underlayer at a substrate temperature of less 240&deg; C., a cobalt-containing magnetite thin film having a plane (400) which is predominantly oriented in parallel with the surface of the plastic substrate, and finally oxidizing the cobalt-containing magnetite thin film in a plasma-activated oxygen atmosphere containing a rare gas at a substrate temperature of less than 240&deg; C. while incorporating the rare gas into oxygen. This results in a cobalt-containing maghemite thin film as a perpendicular magnetic film having a spacing of a plane (400) of not more than 2.082 &angst;. The magnetic recording medium so produced is useful for high-density recording using a plastic substrate.

Process for producing magnetic recording medium

A magnetic recording medium of the present invention comprises: a plastic substrate; and a cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, and having either a spacing of a plane (,) of not more than 2.510 &angst;, a spacing of a plane (,) of not more than 2.415 &angst; or a spacing of a plane (,) of not more than 2.950 &angst;; and has a coercive force of not less than 2,000 Oe. Such magnetic recording medium suitably applicable to existent magnetic recording systems using a ring-type magnetic head and capable of using a plastic substrate for providing a magnetic recording medium for high-density recording.

Growing community of inventors

Ube, Japan

Mitsuru Matsuura