CA2063994C

CA2063994C - Permeable mgo nozzle

Info

Publication number: CA2063994C
Application number: CA002063994A
Authority: CA
Inventors: Bruce Dunworth; Gary Mccorkle
Original assignee: Ferro Corp
Current assignee: Vibrantz Corp
Priority date: 1989-05-01
Filing date: 1990-04-30
Publication date: 2001-06-12
Anticipated expiration: 2010-04-30
Also published as: ES2101697T3; EP0471757A4; ATE150348T1; EP0471757A1; JPH04507377A; CA2063994A1; WO1990013379A1; DK0471757T3; DE69030256T2; RU2070474C1; DE69030256D1; KR920702644A; EP0471757B1; AU5661690A

Abstract

An immersion nozzle (10) for continuous metal casting having an el-ongated nozzle body (12) formed from a porous, gas permeable refractory material. The nozzle body has a conduit (18) extending longitudinally there-through and an inner surface (20) which defines the conduit, The nozzle body also includes an outer surface defining a predetermined body profile and channels (24, 26, 28, 30) formed in the outer surface (16) of the nozzle body. A metallic housing (14) encases the nozzle body and has an inner sur-face (32) dimensioned to substantially conform to the profile of the nozzle body. The housing is secured to the nozzle body by a refractory mortar (40) which forms a rigid relatively airtight layer between the housing and the nozzle body, wherein the channel means form internal passages in the noz-The. A port (34) is provided on the housing in registry with the channels in the nozzle body. The port is connectable to a source of inert gas, which is op-erable to force the gas into the passages and into the porous refractory mate.
rial.

Description

WO 90/t3379 fCT/US9010233t Field of the Invention The present invention relates to c~onents for foundry and steel mill applications, and more particularly to fed nozzles typically fatu~d in ladles and tundishes used for teeming molten metals.
HacJarramd of the Invents ~
Idles and tundishes used for t~mir~g molten steel require an outlet or outlets at the bottojn thereof to dir~act the flora of the molten metal into a subsequent stage, e.g. a tiuxlish, inner mold, or continuous casting molds. These outlets are typically formed by special nozzles made of refractory material having good corrosion resistance. Oontrol of the casting rates of the molten metal is generally carried out by means for either a stopper rad assembly or a slide gate system, both of which include similar refractory materials. Cbnventional nozzles are typically alumina-silica, dzr~e-alumi.na, alumina -graphite or ziroonia-graphite refractories. A problem with such materials is that they have an affinity for impurities in steel, especially in ahaninvm killed steels. In this respect. deposits are apt to cynically and/or. n~ly attach to the inner bore surface of the nozzles and form deposits thereon. These deposits build-up to a point where they restrict flow, and sometimes block the orifice to such a degree that flora stops.
In an attempt to solve the blocJtage problems created by deposit build-ups, it has been known to use porous, gas permeable nozzles to introduce an inert gas into the bore. Permeable nozzles knoGm heretofore generally include a refractory and a metal jacket or housing spaced 2 20fi3994 therefrom, wherein an air space or manifold is defined therebetween. Gas is introduced into the space or manifold thi~ough a fitting in the metal jacket. Pressure builds up between the refractory and the jacket, until it reaches a pressure sufficient to weroc$ne the resistance inherent in the permeable refractory, at which point the inert gas flows thxu~h the refractory into the nozzle bore. Ideally, the introduction of the inert gas creates a gas film along the inner surface of the bore to retard deposit build-up. (An additional advantage of using inert gas is that it creates a positive pressure which prevents introduction of air into the molten metal. Zhis prevents oxidation of the metal.) However, these devices are not capable of directing greater gas flow to specific locations in the bare where the build-up of deposits is most prevelant.
Moreover, while maintaining an inert gas film on the bore of the nozzle increases nozzle life by ~g the build-up of deposits thereon, it does not oc~letely eliminate the d~nicaa. and/or mechanical attraction between conventional nozzle refractory material and the impurities in the molten steel. In this respect, most vonventional nozzles are alumi.na-silica based and hare a strong affinity for imp<irities found in steel.
Other materials, such as nsagnesium oxide (Mg0), which is known to have no affinity for alumi,na, has frond little aoo~tance or use in manufacture of nozzles. With respect to magnesium oxide (Mgp), i~
disfavor may be due to a perceived tendency to cracking.
In any event, the chemical attraction between impurities in molten steel and material found in conventional nozzles, together with the physical shape of the nozzle orifice (which may include areas or shapes WO 90/13379 PCf/US90/02331 2os3~s~
which facilitate deposit build-up) tend to limit nozzle life.
The present invention overccanes these and other problems and pravidns a nozzle for teeming molten steel having a substantially reduced affinity for alunnirsa and other impurities within the molten metal, which nozzle is porous and has a high degree of gas permeability and which provides greater gas flow to specific areas within the nozzle.
Summ~rv of the Invention In accordance with a preferred embodiment of the present invention there is provided an inm~ersion nozzle for continuous metal casting which includes an elongated nozzle body formed from a porws, gas pe~e~le refractory material,. ~e nozzle body has a conduit longitudinally therethrcugh and an inner surface which defines the conduit. The nozzle body also includes an alter surface defining a predetermined body ,pirofile, ail dyarn~el means fozrned al ong the nozzle body. A metallic housing encases the nozzle body. The housing has an inner surface dimensioned to substantially canfortn to the profile of the nozzle body. Means for securing the housing to the nozzle body are provided, which means for securing farms a rigid, relatively air-tight layer between the housing and the nozzle body. wherein the charmel means form internal passages within the nozzle. Port means are provided on the housing in registxy with the charnel means in the nozzle body. The port means are connectable to a source of inert gas, which is operable to force the gas into the passages and into said porous refractory material.
More specifically, the elongated nozzle body is preferably fornied of a mixture of magnesiwn oxide (Mg0) particles of several different grain WO 90/13379 ~ PCT/US90/02331 sizes, wherein the nozzle body has a ~~fine open poroslt~,~~. Fine open porosity meanirig that the passages or interstices between the magnesium oxide (Mg0) particles are relatively small such that inert gas p~~g thtrough the nozzle body provides a uni.fozm layer of microscopic gas bubbles ~ot~g' 'the inner surface of the nozzle bore. Zhe fine porosity also requires a greater back pressure to force the inert gas through the small passages and interstices between the magnesium oxide (Mg0) Particles. It is believed that this relatively-high back pressu~ also assists in maintaining a uniform, relatively thick layer of inert gas along the ~
surface of the nozzle bore thereby deterring contact between the ~lten metal and the conduit surface. Zhis uniform layer of inert gas. together.
with the use of magnesium oxide (Mg0) which has no affinity for alumina bu3,ld-up arr3 is generally mere inert to other itg~urities and allaying agents foutxl in molten steel., p~du~ an innrersion nozzle which is less susceptible to deposit build-up along the inner surface thereof.
'~~Y. ~e present invention provides means for directing the flow of the inert gas into the nozzle bore or ~nduit to a~
which impurity build-up wow.d be most severe. In tt~ .
s ocmprised of annular charn~el,s or gxnotres are formed in the surface of the nozzle body. Each d~arn~el is preferably located adjacent a site within the nozzle bore where impurity build-up is most seve~~
~er~Y Providing a Pressurized source of inert gas immediately adjacent a bore site susceptible to deposit build-ups. It has been fotmd that with such an arrangement, increase flora of the inert gas o~ ~e nozzle wall adjacent the channel. Zhus, with the preset ~~i~~

increased flora of the inert gas may ~ a;,.e~~ ~tO9 9 4 -~- specific locations within the nozzle bore by selective positioning of the channels along the outer surface of the nozzle body.
Also important to the above-mentioned aspects of the present 5 invention is that unlike pernieable nozzles )mown heretofore which typically included a space (i.e. manifold) between the refractory nozzle body and the metal housing or jacket, the metal housing of the present invention is secured directly to the nozzle body, this direct attachment provides several advantages. First, the housing acts as a barrier or seal to prevent the inert gas from escaping outside the surface of the nozzle body. thereby confining and directing the gas flora through the wall of the refractory nozzle toward the conduit therein. end, the housing serves as a reinforcing sleeve to hold the refractory nozzle body together, pz~vet~ing the opening of any thermal-shock cracks which wr~d allow steel to penetrate into the nozzle. The present invention therefore allows the use of materials such magnesium oxide (Mg0) which have a tendency, or perceived tendency, for cracking. Third, the direct housing-to-refractory nozzle arrange~t, facilitates the increased back-pressure created by the fine open nozzle porosity preferred in the present invention. Conventionally known permeable nozzles having manifold (spacing) designs would be subjected to intrinsically higher hoop stresses which can cause the manifold jacket to n., It is an aspect of the present invention to provide a nozzle for ladles or tundishes used for teeming molten steel which has improved operational life over nozzles known heretofore.

WO 90/13379 ~ PGT/US90/02331 20fi3994 Another aspect of the present invention to provide a nozzle as described above which is less susceptible to deposit build-up on the inner surfare thereof .
Another aspect of the present invention is to provide a nozzle as described above wherein the nozzle has a substantially reduced affinity for altm~ina, impurities or alloying agents in molten steel.
A still further aspect of the present invention is to provide a nozzle as defined above wherein the nozzle is gas pern~eable and has a uniform and high degree of porosity.
A still further aspect of the pxesent invention is to provide a nozzle as described above wherein inert gas flow ther~et ~Y
directed to areas of the nozzle bore which are nbre susceptible to the formation of deposits thereon, A still Purthe~ aspect of the present invention is to provide a nozzle as described above wherein the nozzle is made primarily of magnesium oxide (Mgo).
A still further aspect of the present invention is to provide a nozzle as described above which is less susceptible to crar.~ir~g.
A still further aspect of the present invention is the provision of a method of forming a gas permeable component of magnesium oxide (Mgo) for use in fourdZy and steel mill applications for teeming molten steel.
These and other aspects and advantages will beocane apparent from the following description of a preferred embodiment of the invention taken together with the a~anying drawings.
Brief Descrit~tion of the Drawirxts WO 90/13379 PCTlUS90/02331 Zhe invention may take physical form in oextain parts and arrangement of parts, an embodiment of whicfi is described in detail in the specification and illustrated in the aceampariying drawings wherein:
FIG. 1 is a partially-sectioned, perspective view of a permeable ttuxiish nozzle illustrating an embodi~ner~t of the present ~~,ion:
FIG. 2 is a sectional view taken along line 2-2 of FIG. It and FIG. 3 is a sectional view taken along line 3-3 of FIG. 2.
e»tailed Descriution of a P~~farr~
ed ~ ~ ~~'11t Referring now to the drawings wherein the shaaings are for the purpose of . illustrating a preferred embodiment of the invention, and not for the purpose of limiting same, FIG. 1 shows a ~zzle l0 for use in a far teeming molten metal. Nozzle 10 is generally c~rised of a core 12 of porous refractory material su:z~ounded by a housing 14. In the embodiment shc~m, core 12 is generally cylindrical in shape and has an outer surface 16 and an elongated bore or opt is e~cter~;s,g longitudinally ther~ethr~gh along the axis thereof. Fore or opening is defines an inner surface 20. As best seen in FIGS. 2 and 3, opening 18 is generally cylindrical in shape and includes a conical or flared portion 22 at the upper end of core 12. Conical portion 22 is provided to facilitate passage of the molten metal thrwgh opening 18.
Zhe outer surface 16 of core 12 is provided with a plurality of axially-spaced, annular d~annels or grooves 24, 26 and 28 which extend about the periphery of core 12. A slightly larger vertical d~arn~el 30 connects channels 24, 26 and 28 to each other. Zhe position of channels 24, 26 and 28 may vary depending upon the size, configuration and function of the nozzle itself, as will be better understood from the description of the operation of the irnrention set forth below.
~~ing to the present invention, core 12 is comprised of magnesium oxide (Mg0) particles. However, it will be appreciated from a further reading of the specification that the present invention finds advantageous application with other porous ceramic ~~.i~s~ ~ is not limited to magnesium oxide (Mg0). A c~~nical analysis of a nozzle a~~ir~g to the present invention manufactured fr~n sea-water produced magnesium oxide (Mgo) would be:
97.9%

0.8%

Si02 1.2%

~2~3 0. 9%

0.5%
Fe203 - the latter materials being impurities ~~,y found in naturally ooct~rring magnesium oxide (Mg0)~ The magnesium oxide (Mg0) particles farming core 12 may be from naturally occurring material, or may be either fused or brine pzbdu~oed.
The sizing of the particles or drains used to foam core 12 is fairly critical, it being desirable to provide a nozzle porous enough to allow for excellent gas flora therethrvugh. yet dense enough to provide excellent wear resistance. In other wants, it is desirable to prod~,ice a nozzle having a fine, open porosity, Tb this end, nozzle care 12 is prised of a combination of magnesium oxide (Mg0) particles of several different sizes. An example of a nozzle core having sufficiently fine-20fi3994 sized pores and good wear resistance, yet being porous erg to pride good gas flow is as follows:
Particle Size Oc~osition %

Coarsest Fraction- 0.125 "
+
U.S.

Mesh 10%

Coarser Fraction - U.S.40 Mesh + U.S. 50 Mesh20%

Coarse Fraction - U.S.50 Mesh + U.S. 65 Mesh30%

Fine Fraction - U.S.65 Mesh + U.S. 100 20%
Mesh Piper Fraction - U.S.100 Mesh + U.S. 150 5%
Mesh Finest Fraction- U.S.150 Mesh 15%

T otal: 100%

It will of cause be understood that the present inventi~ is not limited to the particle sizes or pes~r~tEages discl~ Vie, ~ ~t acceptable nozzles may be produced with vazy~ pg~ of the above particle sizes. Zhough not specifically tested, it is believed that the following ranges of particle sizes wrml,d be acceptable to produce a satisfactory magnesium oxide (Mg0) core according to the p inventions particle Size Sition % Rome Coarsest Fraction - 0.125" + U.S. 40 Mesh 0-15%

Coarser Fraction - U.S. 40 Mesh + U.S. 50 0-25%
Mesh Coarse Fraction - U.S. 50 Mesh + U.S. 65 0-40%
Mesh Fine Fraction - U.S. 65 Mesh + U.S. 100 0-25%
Mesh l0 2063994 Finer Fraction - U.S. 100 Mesh + U.S. 150 Mesh 0-10%
Finest Fraction - U.S. 150 Mesh 2-20%
The magnesium oxide (Mgo) particles are thoroughly .blended, then mixed with sufficient organic birder and/or water to retain. a fixed shape after forming. The forming operation may be air-rannning, vibration-casting, mechanical or isostatic pressing or other means well knoGm to those skilled in the art of refractory fabrication. The formed article is then dried or cured aryl subsequently fired to a temperature sufficiently high to sinter the magnesium oxide particles together to produce a strong shape. The drying and firing is also aoocm~lished by conventionally kncx~m mPthads. After firing, oor~e 12 may be machined or shaped to a desired dimension or shape. Charnels 24, 26, 28 and 30 may be melded into core 12 during the Forming process, but avocrding to the prefetz~ed embodiment of the present invention, are machir~ed into core 12 after firing.
In the embodiment shown, core 12 is 14&1/2 irxfies in length and has an outer diameter which varies frcen 7&3/16 i.rxW es in diaar~eter at one end to 7& 7/16 inches in diameter at the other end. Bore or openir~g 18 is approximately 3 inches in diameter. It will of oourse be appreciated that the size or shape of core 12 are not critical to the present invention which can find advantageous application in numerous and varied sizes aril shapes~ It being understood that the overall shape of nozzle 10 and/or core 12 is det~~mi.ned by the particular casting machine or system with which it is to be used. As indicated by the dimensions set forth above, oore 12 is slightly conical in shape, i.e. flaring outwardly slightly from top to bottom. this shape is provided to facilitate assembly or nozzle 10 as will be described below, but is not critical to the present invention.
Housing 14 is generally cylindrical in shape and has an inner surface 32 dimensioned to closely match and conform to the outer profile of care 12. A threaded fitting 34 is provided on housing 14. An aperture 36 extends through fitting 34 and housing 14. Housing 14 and core 12 are preferably dimensioned such that a uniformed space or gap 38 of appro~timately .06 to .20 inches is defined therebetw~een. A thin, uniform layer of a eementitious refractory mortar 40 is provided in space or gap 38 to secure housing 14 to refractozy core 12. A conventionally lawwn air-drying mortar or a phosphorio-acid containing mortar may be used.
Fitting 34 is positioned on housing 14 such that when housing 14 is sec~.trec~ to core 12, aperture 36 is aligned with one of d~arn~e.~,s 24, 26, or 30. Housing 14 basically encases core 12 and together with mortar 40 structurally reinforces core 12 as will be discussed in more detail below.
Housing 14 and n~tar 40 also produce a seal aramd core 12 and wen the open portion of channels 24, 26, 28 ant 30. In other words, hcus3,ng 14 and mortar 40 form a generally air-tight barrier wen each channel as best seen in FIG. 3. In the enbodirent shown, housing 14 is formed frrxn a low carbon steel and has a uniform wall thic~~ess of .05 inches. Housing 14 is 14&1/2 inches in length and has an outer diameter which varies from 7&1/2 inches on one end to 7&3/4 inches on the other.
An important aspect of the present invention is the asseimbly of nozzle l0. In this respect, as will be appreciated from a further reading WO 90/13379 ~~ PCT/US90/02331 of the specification, it is ing~ortant to the ~~~ of nozzle 10 that d~am~el.s 24, 26, 28 and 30 .z~nain ~~open~~ and do not ~ by mortar 40 during assembly. the simplest method of assembling nozzle 12 mould be to coat nozzle 12 with mortar and slide housing 14 thereovex.. A
problean with such process, haaever, is that due to the relatively small gap pausing 14 and core 12, n~ov~eme~t of housing 14 over core 12 creates a large hydraulic pressure in mortar 40 which tends to force the ~~r into the d~armels 24, 26, 28 and 30 forn~ed in nozzle 12. It has been found that this pznblezn can be v~reraane by covering the dues with 1o a positionally stable barrier, and more iyortar~tly, ~i~
width of the d~arn~els such that the barrier can withstand the hydraulic pressure e~certed then and not be famed into the dsaru~el. In this it has been found that if an adhesive tape 42, oos~ve~rtianally-l~an duet tape, is used to cover the d~armels tend the width of the d~arn~l.s is maintained less than 1/2 inch, that irrespective of the size of nozzle 10, horsing 14 trey be slid over core 12 without mortar 40 being forced into and obst~s 24, 26, 28 and 30 therein. In the e~odin~t shown, d~armel.s 24, 26, and 28 are appr~timatel.y 1/4 inch wide and 1/2 inch deep, and 30 is 1/2 irx~
wide and 1/2 inch deep. An elongated, ~hap~ . ~~ ~ ~y ~
yin gel 3o as a bridging member to preve~ tape 42 fran being forced into d~artnes 30. Tb further facilitate such assanbly, core 12 and inner surface 32 of hausirx3 14 are slightly conical,, as set forth above arsd as best seen in FIG. 3. After the assembly is oc~leted, and refractory mortar 40 has set, aperture 36 is cleared by madvni~~

mortar 40 or tape 42 which would obstruct its nication with channels 24, 26, 28, arid 30.
Referring now to the operation of the present,invention, nozzle 10 is adapted for use in a tiu~dish to direct the flora of molten metal to a subsequent stage of operation in a steel making process. Nozzle l0 may include flanges or other locating surfaces to facilitate assembly in the tundish in a conventionally la~own fashion. It being understood that present invention is not limited to a specifically shaped or sized nozzle.
In this respect, it is well la~wnn that the physical dimezasions and configuration of a nozzle are determined by the particular casting machine or system with which it is used. Fitting 34 is adapted to be se~~ ~ a sof inert gas in a crnwentionally la~own fashion. the inert gas flows through fitting 34 into channel 24, and into ~ar~els 26, 28 via rharmel 30. When the pressure of the inert gas is sufficient to overcome the resistance inherent in the impermeable magnesium oxide (Mgo) core 12, gas flows thzthe core 12 into the nozzle opening or bore 18. Zhe usual flaw rate of the inert gas in a nozzle as described above is apprrncimately 15 Standard Cubic Feet per Hour (SCFH) with back pressures of between 5 to 10 psi. Importantly, with the present inventi~, the flow of the inert gas may be directed to a specific desired site within nozzle opening 18 by locating the channels 24, 26 and 28 in the outer surface of core 12 at location adjacent the desired sites. In this respect, it has been found that flow of the inert gas through the nozzle wall is greater adjacent the location of a channel. Accordingly, the nozzle may be designed (i.e. the channels may be positioned on core 12) to direct the WO 90!13379 ~~ PCT/US90/02331 flora of the inert gas to areas in which i~urity build-ups within bore or opening 18 would be most severe. In other worc7s, the ~ifia location of channels 24, 26, 28 and 30 in core 12 allows for a high degree of control of the regions in openi~ 18 where it is desirable to have the greatest gas Pressure. It has been found that while the greatest gas pressure in bore 18 is adjacent the location of the d~annels in care ~ ~ ~ ply uniformed distribution of the inert gas is also provided throughout 18 of nozzle 10 due to the fine, open porosity of the refractory core 12 heretofore described.
A nozzle acoordir~g to the present invention has been shown to provide increased operational life and substantially improve the erosion ~i~ance. Moreover, such a nozzle shows a significant in~roveme~
against the build-up of alumina, titani.a and/or other deposits.
remarkable characteristics of the present invention are the result of several factors. Zhe application of magnesium oxide in forming the ~
provides a core having no affinity for alumina or other im~xu-ities found ~llent , porosity characteristics of the oox~e, i. e. the fine-bpen porosity, is believed to generate small, fine bubbles which maintain a minuscule gas gap bet~en the molten metal and surface 20 of bore 18. The relatively high back pressure helps maintain a uniform layer of gas bubbles between the molten metal and surface of the refractory.
ln~ortantly, the ability of the disclosed nozzle to direct the greatest flow of gas to specific locations within the nozzle bore provides maximan gas flea at sites having a susceptibility to deposit build-up. l~ditional advantages of a nozzle according to the present invention is that the 15 2U6399~
attac~ent of housing 14 to core 12, in addition to sealing core 12, makes the present nozzle less susveptible to catast~hic failure due to cracking. In this respect, housing 14 holds the magnesium oxide (Mg0) refractory material together much like a reinforcing band, thus preventing the of any cracks which may be produced in the refractory material as a result of thermal. shocJc.
The present invention has been described with respect to a preferred embodiment. It will be appr~eciatsd that modifications and alterations will oowr to those skilled in the art upon a reading of the specification aryl the claims herein. For example, while the present invention has been described with respect to the use of magnesium oxide in forming core 12, other materials may be utilized to provide a permeable core, and would find advantageous application with other aspens of the pent invenition. Moreover, the present irnrention is mat limited to the Z5 shape and size of the charn~,ls described herein. It will be appx~ciated that other methods of assembly of nozzle l0, which would mat limit the width of the channels, could be provided without deviating from the present lion. For e~le, use of a metallic tape of strip over charnels 24, 26, 28, and 30 world enable wider d~arnye~.s to be used. It is intended that all such modifications a~i alterations be included insofar as they ootne within the scope of the patent as claimed or the equivalents thereof.
Having described the invention the following is claimed.

Claims

We Claim:
An immersion nozzle for continuous metal casting including:
an elongated, generally cylindrical, gas permeable nozzle body formed essentially of magnesium oxide particles, said body having:
a conduit extending longitudinally therethrough;
an inner surface which defines said conduit;
an outer surface defining a predetermined body profile; and spaced-apart annular grooves of predetermined configuration formed in the outer surface of said nozzle body, said grooves disposed at predetermined positions on said nozzle body;
a metallic housing encasing a substantial portion of said nozzle body, said housing having an inner surface dimensioned to substantially conform to said profile of said nozzle body;
cementitious refractory material disposed between said housing and said nozzle body for securing said housing to said nozzle body, said refractory material forming a rigid, relatively air-tight layer between said housing and said nozzle body wherein said annular grooves form internal passages in said nozzle; and port means on said housing in registry with said annular grooves, said port means connectable to a source of inert gas to force said gas into said passages and into said porous refractory, wherein said annular grooves define annular regions of inert gas flow along said inner surface of said conduit, said regions generally corresponding to said predetermined positions.
2. A nozzle as defined in claim 1 wherein said means for securing is a cementitious refractory mortar.
3. A nozzle as defined in claim 1 wherein said nozzle body has a porosity between 20% and 30%.
4. In a gas permeable nozzle for submersion in a molten metal, said nozzle comprised of an elongated body of porous refractory material, said body having an outer surface, an inner surface and a bore extending longitudinally through said body, wherein said bore defines said inner surface, and a metal housing encasing said outer surface of said body, said nozzle adapted to be connected to a source of inert gas wherein said gas flows through said body from said outer surface to said inner surface, the improvement consisting:
said nozzle being formed essentially of magnesium oxide particles of the following sizes:
0.125" + U.S. 40 Mesh 0-15%
U.S. 40 Mesh + U.S. 50 Mesh 0-25%
U.S. 50 Mesh + U.S. 65 Mesh 0-40%
U.S. 65 Mesh + U.S. 100 Mesh 0-25%
U.S. 100 Mesh + U.S. 150 Mesh 0-10%
U.S. 150 Mesh 2-20%
a layer of cementitious refractory material disposed between said housing and said nozzle body, said refractory material forming an airtight layer between said housing and said nozzle body, and channels formed in the outer surface of said elongated body, adjacent said layer of refractory material, said channels connectable to said source of inert gas wherein said inert gas is directed into said nozzle body to effect increase gas flow at specific locations on said inner surface of said bore.
5. An immersion nozzle for continuous metal casting comprising; an elongated, porous body of a predetermined outer configuration comprised essentially of magnesium oxide (MgO) particles, said body including an inner surface, an outer surface, and a bore extending longitudinally through said body, said bore defining said inner surface;
a thin walled metal housing having an inner surface conforming substantially to said outer configuration of said body said housing dimensioned to encase a major portion of the outer surface of said nozzle body, a layer of cementitious refractory material disposed between said housing and said nozzle body for securing said metal housing to said elongated body such that an airtight seal exists therebetween, means for connecting said nozzle to a source of inert gas, and a plurality of spaced-apart annular channels formed in the outer surface of said body between said outer surface of said body and the inner surface of said layer of refractory material, said channels operable to direct said gas through said porous body to said inner surface of said bore and to create annular region of gas flow along said inner surface of said bore.
6. An immersion nozzle as defined in claim 5 wherein said means for directing are channels formed between said outer surface of said body and the inner surface of said metal housing.
7. An immersion nozzle for continuous metal casting comprising; an elongated, porous body of a predetermined outer configuration comprised substantially of magnesium oxide (MgO) particles of the following sizes:
0.125" + U.S. 40 Mesh 0-15%
U.S. 40 Mesh + U.S. 50 Mesh 0-25%
U.S. 50 Mesh + U.S. 65 Mesh 0-40%
U.S. 65 Mesh + U.S. 100 Mesh 0-25%
U.S. 100 Mesh + U.S. 150 Mesh 0-10%
U.S. 150 Mesh 0-20%
said body including an inner surface, an outer surface, and a bore extending longitudinally through said body, said bore defining said inner surface;
a metal housing having an inner surface conforming substantially to said outer configuration of said body, means for securing said metal housing to said elongated body such that an airtight seal exists therebetween, means for connecting said nozzle to a source of inert gas, and a plurality of channels formed in the outer surface of said body between said outer surface of said body and the inner surface of said metal housing, said channels operable to direct said gas through said porous body to said inner surface of said bore.
8. A method of forming an immersion nozzle comprising:
a. forming a porous, refractory nozzle having channels formed in the outer surface thereof, said channels having a predetermined width and being in communication with each other, b. forming a metal housing having an inner surface dimensioned to conform to the outer profile of said porous refractory nozzle, said housing adapted to receive said nozzle with a slight spacing therebetween and having an orifice through a side thereof, c. jacketing said channels in said nozzle with a positionally stable barrier, and d. inserting said refractory nozzle into said housing with a wet cementitious refractory mortar disposed between said nozzle and said housing, and with said orifice in said housing being aligned with one of said channels in said nozzles, e. securing said housing to said refractory nozzle by drying said mortar, said channels remaining open and not obstructed by mortar.
9. A method as defined in claim 8 wherein said refractory nozzle is comprised primarily of magnesium oxide particles.
10. A method as defined in claim 8 wherein the step of forming said nozzle includes the step of blending refractory particles with organic binder and/or water and the method further comprising:
f. drying or curing the formed nozzle, and g. firing the dried or cured refractory nozzle.
11. A method as defined in claim 8 wherein said step of forming said nozzle includes machining said channels into said refractory nozzle after it is formed.
12. A method as defined in claim 8 wherein said channels are annular grooves about the periphery of said refractory nozzle.
13. A method as defined in claim 8 wherein said immersion nozzle is generally cylindrical in shape.
14. A method as defined in claim 8 where said channels are approximately 1/2"
deep and approximately 1/4" to 1/2" wide.
15. A method as defined in claim 8 wherein said step of securing the housing to the nozzle is achieved by allowing the mortar to dry by evaporation.
16. A method as defined in claim 8 including the step of jacketing said channels with an adhesively applied barrier material.
17. A method as defined in claim 8 wherein said metal housing is steel.