Kawasaki Steel Corporation

Amsted Industries Inc.

Yukio Oguchi

Tetsuya Fujii

Hiroyuki Kaito

Shoji Iwaoka

Takashi Ohtani

Akio Ejima

Shuya Yano

Toshihiko Emi

Toshihiko Funahashi

Ryoji Uchimura

Toshio Fujimura

Kenji Saito

Arata Ueda

Norio Sumida

Kenichi Ueda

Kenichi Sorimachi

Tsutomu Nozaki

Hakaru Nakato

Katsuo Kinoshita

Haruji Okuda

Hideshi Ohzu

Kenichi Orito

Kanji Aizawa

Minoru Yao

Toshio Kato

Koji Hosotani

Isamu Goto

Kenji Murata

Norio Sumita

A system for manufacturing fine-grained SiO powder includes means for heating a mixture of an SiO.sub.2 containing material and an Si and/or C containing material for generating SiO vapor, and for condensing the generated SiO vapor from a gaseous state in the presence of non-oxidizing gas and under substantially low pressure. Preferably, vacuum is maintained at the position where thermal reaction generates SiO vapor. Non-oxidizing gas serves for transferring vapor-state SiO and/or fine-grained SiO powder to an SiO collection chamber. This successfully prevents the SiO from being accumulated within a transfer pipe or duct and thus prevents the pipe or duct from being blocked. Furthermore, substantially low pressure (vacuum) atmosphere encourages SiO vapor generation from the reagent mixture and thus permits a lower heating temperature to cause SiO vapor generation.

Method for manufacturing fine-grained silicon monoxide

In an immersion nozzle for continuous casting, at least one portion of reduced a sectional area of passage for molten metal is formed near to the bottom of the nozzle and plural discharge ports symmetrically arranged with respect to the axis of the nozzle are arranged above and below the reduced sectional area portion in the longitudinal direction of the nozzle. Further, molten metal is continuously cast by using the above immersion nozzle together with a static magnetic field.

Immersion nozzle for continuous casting

Hollow metal ingots are produced by a hollow metal manufacturing apparatus comprising a mold placed on a stool, and a cylindrical metallic cooling core placed in the mold to form an annular casting space therebetween. During the casting, a cooling fluid is directly blown upon the inner surface of the core while the cylindrical metallic core is allowed to be buckled. The cooling core is constituted by an outermost metallic cylinder to be brought into contact with a molten metal, a cylindrical lattice-fashioned buckling-adjusting frame positioned in the metallic cylinder and provides passages through which the cooling fluid is passed, and a cooling fluid vessel which is positioned inside the buckling-adjusting frame and is provided with a number of cooling fluid blowing nozzles.

Method and apparatus for producing hollow metal ingots

In producing zirconia powder by desiliconizing heat treatment of a mixture of zircon powder and a powdery carbon-containing material, optionally with addition of a zirconia stabilizing oxide such as calcia or yttria, in a nonoxidizing atmosphere the conversion of silica into SiO and dissipation of gaseous SiO are promoted and completed by performing the heat treatment under reduced pressure, viz. at a pressure not higher than 0.6 atm. Zirconia powder of very high purity can surely be obtained, even when a large batch of the raw material mixture is treated, by performing the reduced pressure desiliconizing heat treatment in two stages: first at 1200.degree.-1550.degree. C. until almost complete conversion of silica to SiO and then at 1550.degree.-2000.degree. C. The mole ratio of C to SiO.sub.2 in the raw material mixture must be 0.4-2.0. For further enhancement of purity, zirconia powder obtained by the desiliconizing treatment may be subjected to oxidation heat treatment. Efficiency of the desiliconizing heat treatment can be enhanced by precedingly forming the raw material mixture into porous lump(s) whose bulk density is in the range from 0.7 to 2.0.

Method of producing high purity zirconia powder from zircon powder

A method of stirring molten metal by repeatedly sucking and rapidly discharging part of the molten metal into and out of a refractory cylinder having a lower opening end immersed in the molten metal in a ladle, comprises operating the stirring under a condition that an inner diameter (d) of the refractory cylinder is less than 1,000 mm, a relation between the inner diameter (d, mm) of the refractory cylinder and weight (W, ton) of the molten metal in the ladle is d/W.sup.0.5 &gt;30, and an immersed depth of the refractory cylinder is within 200-700 mm. A pressurized gas for discharging the sucked molten metal out of the cylinder is introduced thereinto in an inclined direction relative to a vertical line against a point on an opposite inner wall of the cylinder at least 500 mm above the maximum suction level of the molten metal in the cylinder. A refractory cylinder operated in the above manner according to the invention comprises a flange connection between an uppermost and an intermediate cylinder parts of the cylinder at a location higher than the maximum suction height of the molten metal and a further flange connection between the intermediate cylinder part and a lowermost cylinder part. The refractory cylinder comprises at its immersed end a flow restricting opening to obtain more strong stirring the molten metal.

Method of stirring molten metal and refractory cylinder for the purpose

A method of refining molten metal with stirring in a refining vessel by repeated operation of suction and discharge is disclosed, wherein a lower end of a refractory cylinder is immersed into a molten metal bath in the vessel and an inside of the cylinder opposite to the immersed end is alternately subjected to evacuation and pressurization. In this method, maximum and average values of pressure reduction velocity to be applied to the inside of the cylinder are limited to not more than 1,000 mmHg/sec and not more than 500 mmHg/sec, respectively, and an evacuation time is extended over at least 1.5 times intrinsic oscillation period of up and down movement of molten metal column inside the cylinder.

Method of refining molten metal with stirring by repeated operation of

The present invention provides a method for manufacturing complex metallic plates. A hollow metal piece, which will form the outer layer, is first made. A powder which will form the inner layer is then filled within the hollow metal piece. The multi-layer plate is then manufactured by hot-rolling the metal piece.

Method of manufacturing complex metallic plate

High chromium steels having extremely low carbon and nitrogen contents are produced by blowing more than 15 up to 40 Nl/min per ton of molten steel of an inert gas into a high chromium steel containing 0.8 to 2.5% of C and 10 to 35% of Cr in a ladle under a reduced pressure from bottom of a ladle and concurrently blowing oxygen gas to the molten steel surface to form 1 to 100 kg per ton of the molten steel of a slag containing not less than 20% of SiO.sub.2 and not more than 25% of Cr.sub.2 O.sub.3 at the end of oxygen blowing, terminating the oxygen blowing when the carbon concentration in the molten steel becomes not more than 0.020%, and subsequently blowing 6 to 40 Nl/min per ton of molten steel of an inert gas under a high vacuum of not more than 10 torr.

Method for producing high chromium steels having extremely low carbon

A method of denitriding a high chromium molten steel with a minimum chromium loss is disclosed. A high chromium molten steel containing 0.8-2.5% of C and 10-35% of Cr is denitrided to a final nitrogen content of not more than 40 ppm in a ladle under vacuum by flowing an inert gas into molten steel at a flow rate of not less than 15 Nl/min per ton of molten steel and at the same time blowing oxygen gas against molten steel until carbon content [C] in molten steel satisfies the following equations (1) and (2) in accordance with the carbon content prior to decarburization [C] of molten steel:

Method of denitriding a high chromium molten steel with a minimum

A method of producing alloy steels having an extremely low carbon content of not higher than 30 ppm is disclosed. The alloy steels can be obtained by vacuum treating a preliminarily decarburized molten steel in the presence of a proper amount of a slag containing specifically limited amounts of chromic oxide and silicon oxide under an inert gas atmosphere by means of a commonly used degassing apparatus.

Method of producing alloy steels having an extremely low carbon content

Growing community of inventors

Chiba, Japan

Yukio Oguchi