Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Kabushiki Kaisha Kobe Seiko Sho (kobe Steel, Ltd.)

Kazutaka Kunii

Moriyoshi Kanamaru

Katsutoshi Takagi

Naoya Fujiwara

Tatsuhiko Kusamichi

Takao Kawanaka

Jumpei Nakayama

Tomoji Takahashi

Kiyoshi Kiuchi

There is described a method for producing ultrahigh-purity Fe-base, Ni-base, and Co-base alloying materials to achieve impurity levels of (C+O+N+S+P)&#x3c;100 ppm, and Ca&#x3c;10 ppm, in the form of a large ingot, using a refining flux while forcibly cooling the crucible. A refining flux selected from the group consisting of metal elements of the Groups IA, IIA, and IIIA of the Periodic Table, oxides thereof, halides thereof, and mixtures thereof, is added to the molten metal during primary melting and the molten metal is held in contact with the refining flux for at least 5 minutes before tapping. Thereafter, the molten metal is caused to undergo solidification inside a mold, thereby producing a primary ingot. Subsequently, secondary melting is executed by an electron-beam melting method whereby while the primary ingot is sequentially melted in a water-cooled copper mold at a low pressure, the molten metal as-solidified state is pulled out from an outlet side of the water-cooled copper mold, thereby forming an ingot product.

Induction melting apparatus employing halide type crucible, process for producing the crucible, method of induction melting, and process for producing ingot of ultrahigh-purity Fe-, Ni-, or Co-based alloy material

Method for pressing oxynitride glass, disk of oxynitride glass made by said method, and pressing die for said method

Oxynitride glass whose composition is represented by Al&mdash;Si&mdash;O&mdash;N or M&mdash;Al&mdash;Si&mdash;O&mdash;N (where M denotes Ca, Mg, or rare earth element), wherein the content of O and N as non-metallic components is in the range of 0 eq %<N&lE;30 eq %, with O&plus;N&equals;100 eq %, the content of M, Al, and Si as metallic components is in the range of 20 eq %&lE;Al&lE;30 eq % and 70 eq %&lE;Si&lE;80 eq %, respectively, with Al&plus;Si&equals;100 eq % (if M does not exist) and the content of M, Al, and Si as metallic components is within the hatched area in the composition diagrams shown in FIGS.,to,, if M is Ca, Mg, or rare earth metal, or within the hatched area in the composition diagrams shown in FIGS.,to,, if the content of N is in the range of 5 eq %&lE;N&lE;25 eq %. This glass is superior in specific rigidity and fabricability. It contains nitrogen in a controlled amount so that it has improved specific rigidity without its specific gravity increasing.

Glass with high specific rigidity for recording medium

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Kobe, Japan

Kazutaka Kunii