Dispensing – Molten metal dispensing – With subjacent flow guide
Patent
1998-07-13
1999-11-09
Kastler, Scott
Dispensing
Molten metal dispensing
With subjacent flow guide
266280, B22D 1110
Patent
active
059797207
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIAL FIELD OF THE INVENTION
The present invention relates to nozzles used in continuous casting of steel, such as submerged nozzles, long nozzles, etc.
PRIOR ART
Al.sub.2 O.sub.3 --SiO.sub.2 --C nozzles have been the most widely used in the continuous casting of aluminum killed steel because of their superior resistance to corrosion and spalling. However, blockage inside the nozzle pipe remains a problem due to the adhesion of Al.sub.2 O.sub.3 inclusions caused by deoxidization of aluminum in the steel.
The mechanism behind the blockage is as follows: the SiO.sub.2 and C used as raw materials. The gaseous SiO and gaseous CO generated diffuse at the interface between the nozzle and the molten steel and react with the Al in the steel according to Reactions (2) and (3), to form a layer of Al.sub.2 O.sub.3 network on the inner wall of the nozzle, which initiates the adhesion of Al.sub.2 O.sub.3 inclusions.
Here (s) stands for solid phase, (g) stands for gaseous phase, and Al, Si, and C represent Al, Si, and C dissolved in the molten steel, respectively.
As the adhesion of Al.sub.2 O.sub.3 inclusions progresses, nozzle blockage will occur. This not only shortens the working life of the nozzle, but also impedes continuous casting operation. Therefore, it is important to prevent the nozzle blockage.
To try to solve the above problems, Japanese Patent Laid-Open No. 51-54836 discloses a method of coating the interior surface of a submerged nozzle with a refractory containing no carbon with the aim of preventing Reaction (1), in other words, the inner surface of the nozzle runner is covered with a refractory containing one or more of Al.sub.2 O.sub.3, MnO.sub.2, MgO, CaO, or SiO.sub.2. However, the range of 90 to 99 percent by weight of SiO.sub.2 considered desirable in said publication creates a layer of Al.sub.2 O.sub.3 network on the inner wall of the nozzle by Reaction (4) below:
The Al.sub.2 O.sub.3 thus formed and the Al.sub.2 O.sub.3 inclusions in the steel adhere to the surface of the SiO.sub.2 then dissolve into the SiO.sub.2 and form a layer with a melting point less than 1600.degree. C. In continuous casting, this layer with a low melting point is swept away by the molten steel causing damage to the nozzle.
As a countermeasure to this, Japanese Patent Laid-Open No. 3-243258 discloses a carbonless high alumina refractory having at least 90 percent by weight or more of Al.sub.2 O.sub.3 (or MgO) and containing not more than 5 percent by weight of SiO.sub.2. Further, Japanese Patent Laid-Open No. 5-154628 discloses a nozzle for use in continuous casting whose interior body is composed mainly of alumina clinker with an alumina content of at least 99 percent by weight, having a refractory component with an alumina content of at least 70 percent by weight, a carbon content of less than 1 percent by weight, and a silica content of less than 1 percent by weight, and having a grain constitution in which 20 to 70 percent by weight of the grains are 0.21 mm or less.
These interior bodies can be made by simultaneously pressure molding the raw material mix of the interior body and the raw material mix of the main body of the nozzle, or by packing the raw material mix of the interior body onto the preformed main body of the nozzle to finish it. However, in either method, the coefficient of expansion of the carbonless material composing the interior body filling the interior is markedly greater than the coefficient of expansion of the carbonaceous material in the main body of the nozzle and cracks may form in the nozzle matrix during preheating and during use.
Problems the Invention Aims to Solve
To overcome this, Japanese Patent Laid-Open No. 8-57601 discloses a nozzle for use in continuous casting characterized in that in the latter manufacturing process, where the main body of a nozzle for use in continuous casting is formed from a refractory material containing a source of carbon and the portions through which molten steel will flow or with which molten steel will come into contact are coated with a refr
REFERENCES:
patent: 4210264 (1980-07-01), Kondo
patent: 4510191 (1985-04-01), Kagami et al.
patent: 4682718 (1987-07-01), Wanatabe et al.
U.S. Patent Application, Serial No. 08/889,811, filed Jul. 8, 1997, by Takashi Yamamura et al., entitled "Nozzle For Use In Continuous Casting of Steel", located in Group Art Unit 1742.
Japanese Patent Abstract JP408002975A of Japanese Application No. JP 06137542, Jan. 1996.
Database WPI, Section Ch, Week 7626, Derwent Publications Ltd., London, GB, Class M22, AN 76-49024X, XP002083540 & JP 51 054836 A 9Nippon Steel Corp), May 14, 1976 * abstract *.
Patent Abstracts of Japan, vol. 016, No. 034 (M-1204), Jan. 28, 1992 & JP 03 243258 A (Nisshin Steel Co. Ltd), Oct. 30, 1991 * abstract *.
Patent Abstracts of Japan, vol. 017, No. 548 (M-1490), Oct. 4, 1993 & JP 05 154628 A (Kurosaki Refract Co Ltd; Others: 01), Jun. 22, 1993 * abstract*.
Patent Abstracts of Japan, vol. 096, No. 007, Jul. 3, 1996 & JP 08 057601 A (Kurosaki Refract Co Ltd; Nippon Steel Corp), Mar. 5, 1996 * abstract *.
Database WPI, Section Ch, Week 8208, Derwent Publications Ltd., London, GB; Class A81, A82-14704E, XP002083541 & JP 57 07868 A (Harima Taika Renga KK), Jan. 16, 1982 * abstract *.
Lin Wei
Nakamura Ryosuke
Nomura Osamu
Kastler Scott
Shinagawa Refractories Co. Ltd.
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