Leak-Proof Upper Tundish Nozzle

Abstract

A gas injected upper tundish nozzle including: a protective can; a ceramic inner portion disposed within the protective can, the ceramic inner portion having gas flow pathways therein; a gas injection port attached to the protective can allowing for the injection of gas through the protective can and into the gas flow pathways within the ceramic inner portion. A gas flow seal is formed between the protective can and the ceramic inner portion. The gas flow seal blocks gas leakage from the gap between the protective can and the ceramic inner portion. The gas flow seal is formed of nickel or an alloy of nickel.

Claims

1-14. (canceled)

15. A gas injected upper tundish nozzle, the nozzle comprising: a protective can; a ceramic inner portion disposed within the protective can, the ceramic inner portion having gas flow pathways therein; a gas injection port attached to said protective can, the gas injection port allowing for injection of gas through the protective can and into the gas flow pathways within said ceramic inner portion; a gas flow seal formed between the protective can and the ceramic inner portion, the gas flow seal blocking gas leakage from the gap between the protective can and the ceramic inner portion, the gas flow seal being formed of nickel or an alloy of nickel.

16. The gas injected upper tundish nozzle as recited in claim 15 wherein the gas flow seal is formed by depositing the nickel or the nickel alloy into any gaps between the protective can and the ceramic inner portion by a method selected from the group consisting of electroplating, electroless plating, nickel or nickel alloy foil strip application, sputtering, plasma vapor deposition, and metal printing.

17. The gas injected upper tundish nozzle as recited in claim 16 wherein the gas flow seal is formed by electroplating the nickel or the nickel alloy into any gaps between the protective can and the ceramic inner portion.

18. The gas injected upper tundish nozzle as recited in claim 17 wherein the nickel or the nickel alloy is electroplated across the gap on an exterior of the protective can and the ceramic inner portion.

19. The gas injected upper tundish nozzle as recited in claim 18 wherein the nickel or the nickel alloy is electroplated after the protective can and the ceramic inner portion have been formed into a unitary piece.

20. The gas injected upper tundish nozzle as recited in claim 16 wherein the nickel or the nickel alloy is deposited onto one or both of an interior surface of the protective can and an exterior surface of the ceramic inner portion.

21. The gas injected upper tundish as recited in claim 20 wherein the nickel or the nickel alloy is deposited before the protective can and ceramic inner portion have been formed into a unitary piece.

22. The gas injected upper tundish nozzle as recited in claim 15 wherein the protective can is formed of a metal material.

23. The gas injected upper tundish nozzle as recited in claim 22 wherein the protective can is formed of a steel material.

24. The gas injected upper tundish nozzle as recited in claim 15 wherein the ceramic inner portion is formed from a porous ceramic material and the gas flow pathways include pores within the porous ceramic material.

25. The gas injected upper tundish nozzle as recited in claim 24 wherein the ceramic inner portion is formed from a gas permeable refractory material consisting of a ceramic oxide of one or more of aluminum, silicon, magnesium, chromium, or zirconium, or mixtures thereof.

26. The gas injected upper tundish nozzle as recited in claim 15 wherein the ceramic inner portion is not porous or gas permeable and the gas flow pathways are formed directly into the body of the ceramic inner portion.

27. The gas injected upper tundish nozzle as recited in claim 26 wherein the gas flow pathways include a gas distribution manifold and gas distribution channels.

28. The gas injected upper tundish nozzle as recited in claim 27 wherein the gas distribution channels having gas outlets to release the gas into steel flowing within the upper tundish nozzle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 depicts a cross section of a continuous casting line in which the upper tundish nozzle of the present invention is preferably used;

[0019] FIG. 2 is a closer view of the tundish and the casting mold and specifically shows the position of the upper tundish nozzle;

[0020] FIG. 3 is a simplified cross section of an upper tundish nozzle;

[0021] FIG. 4 depicts a typical cross-sectional view of an upper tundish nozzle and specifically indicates gaps through which gas may leak;

[0022] FIG. 5 depicts a cross-sectional view of an upper tundish nozzle including the inventive gap seal solution.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention is an improved argon injected upper tundish nozzle 4 which minimizes/eliminates unwanted leakage of inert gas (such as argon) therefrom.

[0024] FIG. 4 depicts a typical cross-sectional view of an upper tundish nozzle 4. The figure indicates the main components such as the protective can 5, the ceramic inner portion 6, the argon injection port 7 and the argon gas flow path 8 within the ceramic inner portion 6. In this type of upper tundish nozzle 4, the ceramic inner portion 6 may or may not be porous, but the argon flow path 8 (including a gas distribution manifold and gas distribution channels which include gas outlets to release the gas into the bore of the nozzle) is molded into the ceramic inner portion 6 during production. As described above, the ceramic inner portion 6 may alternatively be formed of a porous ceramic without pre-made gas flow paths 8.

[0025] FIG. 4 also depicts the problems addressed by the present invention. That is, there can be significant leakage of argon gas from the gap between the protective can 5 and the ceramic inner portion 6. The leakage paths 10 can be at the top and bottom gaps. In production the inner ceramic portion 6 is press formed into the protective can 5 thereby forming a unitary piece. Due to the difference in thermal expansion between the metal protective can 5 and the ceramic inner portion 6, it is very difficult, if not impossible to for a gas tight seal between them. While these gaps may seem small and insignificant, it should be noted that for a typical upper tundish nozzle 4, a gap of 0.04318 mm between the protective can 5 and the ceramic inner portion 6 has the same flow area as a 3.175 mm pipe. This can result in significant loss of argon volume and pressure.

[0026] FIG. 5 depicts the inventive solution devised by the present inventors. The inventors have found that a seal 11, 11 between the protective can 5 and the ceramic inner portion 6 can plug the leaks of argon. Specifically, the seal 11, 11 is formed of nickel or a nickel alloy. The temperature at the interface between the protective can 5 and the ceramic inner portion 6 is lower than the melting point of the nickel/alloy seal 11, 11. It is believed that this seal 11,11 remains ductile at the elevated temperatures within the gap and stretches without cracking during expansion of the protective can 5 and the ceramic inner portion. This helps to prevent the gaps from leaking.

[0027] The inventors pressure tested an as received commercial upper tundish nozzle 4 to determine if there were leaks in the gaps between the protective can 5 and the ceramic inner portion 6 thereof. The nozzle pressurized and a soapy water solution was applied to the gaps. Bubbles formed, indicating significant leakage of the gas.

[0028] The inventors electroplated nickel onto the upper tundish nozzle 4 in areas that completely overlapped the gap between the protective can 5 and the ceramic inner portion 6. After the electroplating of the seal 11, 11, the nozzle was again pressure tested and it was seen that the leaks had been plugged. This was of course at room temperature and not at steel casting temperatures.

[0029] Next the can with the electroplated nickel seals 11, 11 was subjected to thermal testing by pouring liquid steel into the nozzle using a 100 lb open air furnace. The pour went from a ladle through the upper tundish nozzle 4 into an ingot mold under the nozzle. After the steel solidified, the nozzle was examined, and it was found that the electroplated nickel seal 11,11 was completely intact and even survived a direct metal splash.

[0030] The present inventor envisions two different types of nickel seals. The first type of nickel seal 11 is described above. It is applied externally to cover the gaps between the protective can 5 and the ceramic inner portion 6. This type of seal 11 is generally applied after the upper tundish nozzle 4 is formed.

[0031] Alternatively, the nickel material may be applied to one or both of the protective can 5 and the ceramic inner portion 6 before the upper tundish nozzle 4 is formed. The nickel is deposited strategically on the protective can 5 and/or ceramic inner portion 6 to form the nickel seal 11 there between.

[0032] While the inventors have used electroplating to deposit the nickel seals 11,11. Other viable techniques include electroless plating, nickel foil strips, sputtering, plasma deposition, metal printing and the like. What is important is not how the nickel got into position but rather forming the nickel seal 11,11 between the protective can 5 and the ceramic inner portion.