Nippon Crucible Co., Ltd.

Kazumasa Murakami

Tamio Okada

Takashi Natori

An immersion nozzle for continuous casting resistant to the corrosive action of the melt and the covering material in a mold is made of a refractory material comprising a mixture of electrically conductive graphite and/or silicon carbide, at least one member selected from the group consisting of alumina, zircon, zirconia, fused silica and a metallic silicon, and a binder. The nozzle is covered with a thermal insulating cover having a thickness of approximately 60 mm and made of fused silica containing fibers. The nozzle is preheated without moving it from its operating position by connecting a pair of electrical terminals to opposite ends thereof and passing electric current through the nozzle between the terminals for a period of time sufficient to raise the temperature of the nozzle sufficiently to prevent cracking, spalling, etc. during casting operation. After the preheating is completed the terminals may be removed from the nozzle. The insulating cover may be retained on the nozzle during tapping or the portion thereof that is immersed in the melt may be cut away.

Method of preheating immersion nozzle for continuous casting

A method of making an immersion nozzle or a long stopper, which comprises kneading 3 to 15% by weight of a binder capable of forming a carbon bond upon burning to decompose the binder in a reducing atmosphere with a granular material consisting of 48 to 82% by weight of zircon sand, 10 to 35% by weight of natural flake graphite and 1 to 8% by weight of silicon; molding the kneaded mixture using an isostatic press at a pressure of 500 to 1500 kg/cm.sup.2 ; burning the molded product in a reducing atmosphere at a temperature of 900.degree. to 1200.degree. C; and applying a glassy coating to the outer surface of the burned product.

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Nagoya, Japan

Kazumasa Murakami