KR20160064626A - Nozzle and manufacturing method for nozzle - Google Patents

Nozzle and manufacturing method for nozzle Download PDF

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Publication number
KR20160064626A
KR20160064626A KR1020140168457A KR20140168457A KR20160064626A KR 20160064626 A KR20160064626 A KR 20160064626A KR 1020140168457 A KR1020140168457 A KR 1020140168457A KR 20140168457 A KR20140168457 A KR 20140168457A KR 20160064626 A KR20160064626 A KR 20160064626A
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KR
South Korea
Prior art keywords
calcia
magnesia
zirconia
line portion
nozzle
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KR1020140168457A
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Korean (ko)
Inventor
윤상현
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주식회사 포스코
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Priority to KR1020140168457A priority Critical patent/KR20160064626A/en
Publication of KR20160064626A publication Critical patent/KR20160064626A/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/08—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like for bottom pouring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/14—Closures
    • B22D41/22—Closures sliding-gate type, i.e. having a fixed plate and a movable plate in sliding contact with each other for selective registry of their openings
    • B22D41/28—Plates therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/14—Closures
    • B22D41/22—Closures sliding-gate type, i.e. having a fixed plate and a movable plate in sliding contact with each other for selective registry of their openings
    • B22D41/28—Plates therefor
    • B22D41/30—Manufacturing or repairing thereof
    • B22D41/32—Manufacturing or repairing thereof characterised by the materials used therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles
    • B22D41/52—Manufacturing or repairing thereof
    • B22D41/54—Manufacturing or repairing thereof characterised by the materials used therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles
    • B22D41/58—Pouring-nozzles with gas injecting means

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

The present invention relates to a nozzle and a method of manufacturing a nozzle, and more particularly, to a nozzle and a nozzle having a nozzle body capable of moving molten steel therein. A slag line portion surrounding at least a part of the outer wall of the nozzle body and in contact with the slag; And a discharge port through which the molten steel can move outwardly from the inner work, wherein the slag line portion includes calcium oxide (CaO) · magnesia (MgO) partially stabilized zirconia. In the nozzle, It is possible to suppress or prevent the slag line portion of the used immersion nozzle from being cracked due to thermal shock due to temperature change during preheating or casting.

Description

Technical Field [0001] The present invention relates to a nozzle manufacturing method,

The present invention relates to a nozzle and a method of manufacturing a nozzle, and more particularly, to a nozzle and a nozzle manufacturing method capable of suppressing the occurrence of cracks in a slag line portion during continuous casting to improve the anti-scrubbing property.

The continuous casting process is a process in which a ladle containing refined molten steel is seated in a continuous casting machine and the molten steel in a liquid state is changed from a ladle to a tundish to a mold, . At this time, the immersion nozzle is positioned at the lower portion of the tundish so that the molten steel is moved from the tundish to the mold, and is immersed in the molten steel and contacts the molten steel for a long time, so that excellent durability is required.

The immersion nozzle as is usually excellent in corrosion resistance of alumina to the refractory and the molten metal (Al 2 O 3) and inclusions was small, the wettability expansion amount is smaller with respect to (slag composition) Al 2 combining graphite (C) a thermally conductive good O 3 -C material. However, in such an immersion nozzle containing Al 2 O 3 -C, there is a problem that the slag line portion abutting the slag at the outer peripheral portion is easily molten by the flux of the low-salt air included in the slag and can not be used for a long time.

In order to solve this problem, ZrO 2 -C material is used for the slag line portion. Since the unstable zirconia, for example, pure zirconia, has a large volume change due to the phase change during use, it causes cracks or peeling due to shrinkage and expansion (Partially Stabilized Zirconia (PSZ)) in which calcium oxide (CaO) is used as a stabilizer, as disclosed in Korean Patent No. 10-0258131 (2000.03.08) and the like. However, in calcium oxide partially stabilized zirconia (hereinafter referred to as Ca-PSZ), calcium oxide precipitates during preheating of the immersion nozzle, and calcium oxide precipitated from Ca-PSZ is located at the grain boundary of Ca-PSZ, (12CaO · 7Al 2 O 3 ) is generated by the reaction, thereby adversely affecting the corrosion resistance of the slag line portion. The slag having a low surface tension is easily infiltrated into the grain boundary of the Ca-PSZ and spalled to the slag line portion. . ≪ / RTI >

KR 10-0258131B

The present invention provides a method of manufacturing a nozzle and a nozzle capable of suppressing phase transition of zirconia according to a temperature change.

The present invention provides a nozzle and a nozzle manufacturing method capable of suppressing or preventing cracking of the immersion nozzle during continuous casting.

A nozzle according to an embodiment of the present invention includes: a nozzle body having an inner circumference capable of moving molten steel; A slag line portion surrounding at least a part of the outer wall of the nozzle body and in contact with the slag; And a discharge port through which the molten steel can move outwardly from the inner work, wherein the slag line portion includes calcium oxide (CaO) and magnesia (MgO) partially stabilized zirconia.

The partially stabilized zirconia of CaO and MgO may be employed in an amount of 3 to 10 wt% based on the total weight of the partially stabilized zirconia of CaO and MgO.

The partially stabilized zirconia of CaO and MgO is composed of 85 to 97% by weight of zirconia, 2 to 8% by weight of calcia and / or zirconia, based on the total weight of the partially stabilized zirconia of CaO and MgO, 1 to 7% by weight of magnesia.

The calcined zirconia (CaO) -magnesia (MgO) may be 70 to 85 wt% of the slag line portion.

The slag line portion may further include graphite (C), and the graphite may be 15 to 30 wt% of the slag line portion.

The calcia (CaO) -magnesia (MgO) partially stabilized zirconia may have tetragonal and cubic phases.

The nozzle may have an apparent porosity of 16% or less.

A method of manufacturing a nozzle according to an embodiment of the present invention includes the steps of mixing calcia and magnesia partially stabilized zirconia in which calcia (CaO) and magnesia (MgO) are solid-solved in zirconia (ZrO 2 ) and graphite (C); Molding a slag line portion surrounding a part of the outer wall of the nozzle body with a mixture of the calcia-magnesia partially stabilized zirconia and graphite; And a step of heat-treating the molded body in which the slag line portion is molded.

In the step of mixing the calcia-magnesia partially stabilized zirconia and the graphite (C), a binder may be added. At this time, a phenol resin may be used as the binder.

The nozzle and nozzle manufacturing method according to the present invention can suppress or prevent the slag line portion of the immersion nozzle used in a nozzle, for example, a continuous casting process, from cracking due to preheating or thermal shock due to temperature change during casting. That is, zirconia can be maintained in a stable phase by preparing slag line portions of an immersion nozzle by using zirconia in which calcia (CaO) and magnesia (MgO) are solid-dissolved. Therefore, it is possible to suppress or prevent the volume change of zirconia due to the temperature change, thereby preventing or preventing the occurrence of cracks in the slag line portion during preheating of the immersion nozzle or casting. Accordingly, the lifetime of the immersion nozzle can be improved, and the time and cost required for the immersion nozzle replacement can be reduced.

1 is a schematic view showing a continuous casting machine according to an embodiment of the present invention;
2 is a cross-sectional view of an immersion nozzle according to one embodiment of the present invention.
3 is a diagram showing a phase transition state of zirconia (ZrO 2 ).
4 is a phase equilibrium of calcia partially stabilized zirconia (ZrO 2 -CaO).
5 is a phase diagram of magnesia partially stabilized zirconia (ZrO 2 -MgO).
6 is a three-component phase diagram of calcia, magnesia and zirconia.
7 shows the equilibrium diagram of calcia-magnesia partially stabilized zirconia (ZrO 2 -CaO-MgO) phase at 1220 ° C.
8 shows the equilibrium diagram of calcia-magnesia partially stabilized zirconia (ZrO 2 -CaO-MgO) phase at 1420 ° C.
9 is a schematic diagram of the structure of an immersion nozzle slag line portion according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. In the description, the same components are denoted by the same reference numerals, and the drawings are partially exaggerated in size to accurately describe the embodiments of the present invention, and the same reference numerals denote the same elements in the drawings.

First, the nozzle according to the present invention can be used for injecting or supplying various high-temperature fluids to other containers. Herein, the immersion nozzle for supplying molten steel from a tundish to a mold in continuous casting will be described.

FIG. 1 is a schematic view showing a continuous casting machine according to an embodiment of the present invention, and FIG. 2 is a sectional view of an immersion nozzle according to an embodiment of the present invention. Figure 3 is a view showing a phase change state of the zirconia of the (ZrO 2), phase diagram, and Figure 5 is a magnesia partially stabilized zirconia (ZrO 2 -MgO) of Figure 4 is calcia partially stabilized zirconia (ZrO 2 -CaO) phase diagram, and Figure 6 is calcia, magnesia and zirconia, and three-component phase diagram, Figure 7 is calcia, magnesia stabilized zirconia part (ZrO 2 -CaO-MgO) in 1220 ℃ a phase diagram, Fig. 8 (ZrO 2 -CaO-MgO) phase balance at 1420 ° C., and FIG. 9 is a schematic diagram of the structure of the slurry line portion of the immersion nozzle according to an embodiment of the present invention.

1, the continuous casting machine includes a tundish 10 serving to store and dispense molten steel 60 from a ladle, which is a container for containing refined molten steel, a stopper 10 for controlling the flow rate of molten steel 60, An immersion nozzle 40 for discharging the molten steel 60 to the mold 50 and a mold 50 for making the molten steel 60 into a casting 61 by solidifying the molten steel 60 and the sliding plate 30, . 1 shows that the stopper 20 and the sliding plate 30 are provided at the same time in order to control the flow rate of the molten steel. However, in the actual operation, any one of the stopper 20 and the sliding plate 30 can be used have.

2, the continuous casting immersion nozzle includes a nozzle body 41 having a durability against which molten steel can move, a slag line portion 42 surrounding at least a part of the outer wall of the nozzle body 41 and in contact with the slag, And a discharge port 43 through which the molten steel can move to the outside, that is, the mold, from the inner rim.

The nozzle body 41 has an inner work capable of moving molten steel and can be formed using any one of Al 2 O 3 -C or Al 2 O 3 -SiO 2 -C in a cylindrical shape.

The slag line portion 42 is formed to protrude from the outer surface of the nozzle body 41 on the outer surface of the nozzle body 41 or to contact the outer surface of the nozzle body 41 on which the slag line portion 42 is formed, So that the height of the outer surface and the outer surface of the nozzle body 41 can be made constant.

Referring to FIG. 3, the unsanitized zirconia is phase-changed into a monoclinic tetragonal cubic phase according to a change in temperature during use. At this time, there is almost no change in volume in the case of the phase change from tetragonal to cubic, or from the cubic phase to the tetragonal phase, but from about 3 to 5% at the phase change from the singlet to the tetragonal phase, The volume change is generated. For example, zirconia having a top phase from tetragonal to monoclinic causes volume expansion of about 3 to 5%. This change in the volume of the faced zirconia serves as a cause of cracking due to the temperature change.

Accordingly, a stabilizing agent such as magnesia (MgO) or calcia (CaO) is employed as zirconia in an amount of less than 20 mol% so as to maintain a relatively stable tetragonal or cubic phase at room temperature without phase transition.

However, in the case of calcia partially stabilized zirconia (Ca-PSZ) containing 2 to 4 parts by weight of calcia, as shown in FIG. 4, by eutectoid decomposition at a preheating temperature of about 900 ° C., The same phase transition occurs.

ZrO 2 (t) -> ZrO 2 (c) + ZrO 2 (m) where t is tetragonal, c is cubic and m is monoclinic.

That is, according to the above equation, tetragonal zirconia is phase-changed into cubic and monoclinic. As a result, cracks due to volumetric expansion of zirconia are generated, cracks propagate due to thermal shock during casting, slag is infiltrated through such cracks, and spoiling occurs in the immersion nozzle, thereby causing a problem that the slag line portion is damaged.

On the other hand, in the case of the magnesia partially stabilized zirconia (MgO-PSZ) in which the magnesia is stabilized as the stabilizer, the unstabilized zirconia (Monoclinic ss + MgO) phase transition occurs due to Tetragonal ss + MgO. That is, the magnesia partially stabilized zirconia is phase-transformed from a relatively stable tetragonal phase to a monoclinic phase to cause a volume expansion, thereby generating cracks.

As described above, since the slag line portion of the immersion nozzle has a large volume change according to the unstable state in the tetragonal state of the temperature change, there is a defect that causes cracks or peeling due to the structure and the solution due to contraction and expansion. In the present invention, (Partially Stabilized Zirconia (PSZ)) is used to manufacture the slag line portion, so that the zirconia can maintain a relatively stable phase of the tetragonal phase or the cubic phase even if the temperature changes.

Fig. 6 shows the phase equilibrium diagram of a three-component system of calcia-magnesia-zirconia. Here, the components shown at the vertexes indicate that the closer to the vertices the more components are included. And the lines shown in the phase equilibrium show that all the compositions corresponding to the line exist in a liquid state at the temperature indicated for each line. In the phase equilibrium diagram, the calcia and magnesia partially stabilized zirconia used as the slag line portion of the immersion nozzle according to the present invention shows the lowest temperature at which the liquid phase becomes 1982 ° C, which is the preheat temperature of the immersion nozzle of 1000 ± 200 ° C, Which is higher than the casting process temperature of about 1550 ° C. Accordingly, even if the slag line portion of the immersion nozzle is formed of the calcia · magnesia portion stabilized zirconia, there is no problem that the immersion nozzle is preheated or the slurry line portion of the immersion nozzle, that is, the slurry line portion of the immersion nozzle, is damaged during the continuous casting process.

The slag line portion is composed of calcia-magnesia partially stabilized zirconia in which calcia (CaO) and magnesia (MgO) are solid-dissolved together. At this time, the slag line portion may contain 70 to 85% by weight of zirconia in which calcia and magnesia are dissolved, and 15 to 30% by weight of graphite. In this case, the zirconia in which the calcia and magnesia are solid may be in the range of 3 to 10 wt% of calcia and magnesia, more preferably in the range of 85 to 97 wt% of the total weight of the partially stabilized zirconia of calcia and magnesia Zirconia, 2 to 8% by weight of calcia and 1 to 7% by weight of magnesia.

Here, the calcia-magnesia partially stabilized zirconia is used as a main material of the slag line portion 42 as a refractory material for enhancing corrosion resistance to slag (or flux), molten steel and the like. Particulate stabilized zirconia of calcia and magnesia is less than 70 wt%, the proportion of graphite (C) which is weak in strength and corrosion resistance is increased, and the proportion of partially stabilized zirconia of calcia and magnesia which is excellent in strength and corrosion resistance is low, The corrosion resistance is not sufficient, and when it is more than 85 wt%, the proportion of graphite having excellent thermal shock resistance becomes too small, and the thermal shock resistance may be deteriorated. Calcia and magnesia can be used as stabilizers to inhibit the crystal structure transition depending on the temperature of zirconia. When the calcia and magnesia are solubilized in an amount of less than 3 wt% or more than 10 wt%, zirconia undergoes phase transition to the monoclinic phase due to the temperature change, and cracks may occur in the slag line portion due to the volume change due to the phase transition.

7 and 8, it can be seen that the calcia and magnesia partially stabilized zirconia forms mostly tetragonal (Tss) and cubic (Css) states at 1220 ° C and 1420 ° C. At this time, in the phase balance diagram of FIG. 7, the upper side surface region shows a region where calcia or magnesia is solved solely in zirconia. In this region, in the process of preheating the immersion nozzle, the calcia and magnesia partially stabilized zirconia is monosubstantially There is a problem of being a phase change. 8 is a region having a composition ratio of the partially stabilized zirconia of calcia and magnesia as shown in the phase balance diagram of FIG. 8, and the total amount of partially stabilized zirconia of the calcia and magnesia is present as tetragonal (Tss) and cubic (Css) . On the other hand, the region (b) is a region where the composition ratio of each component of the calcia-magnesia partially stabilized zirconia is out of the range of the composition ratios given above, and here, the total amount of the partially stabilized zirconia of the calcia and magnesia exists as the cubic normal (Css) . Since the stabilization ratio is lower than that of the tetragonal phase, the cubic phase has a high possibility of being phase-shifted to a single phase, and thus, there is a problem that the anti-scrubbing property is poor.

When the content of magnesia in the calcia and magnesia partially stabilized zirconia is less than 85% by weight (b) in FIG. 8), the entire amount is present as cubic at 1420 ° C, and when it exceeds 97% by weight There is a problem that monoclinic is formed on the upper side of the region. And it is more advantageous to stabilize the phase of zirconia by increasing the content of calcia among the calcia and magnesia than the content of magnesia.

The slag line portion 42 may further include graphite (C). Graphite is low in wettability to slag (or flux), molten steel, and has high thermal conductivity. It can be used to reduce wettability of zirconia to improve resistance to invasion and to impart thermal shock resistance to temperature changes. Graphite may be graphite impregnated and may account for 15 to 30 wt% of the slag line portion. If the graphite content is less than 15 wt%, the invasiveness and thermal shock resistance may be deteriorated. If the graphite content is more than 30 wt%, the thermal conductivity is high, The strength and corrosion resistance may be reduced.

Thus, the slag line portion 42 can be formed using calcia-magnesia partially stabilized zirconia (hereinafter referred to as Ca Mg-PSZ) in which calcined CaO and magnesia (MgO) are dissolved, 41).

Hereinafter, a method of manufacturing a nozzle according to an embodiment of the present invention will be described.

The nozzle manufacturing method according to an embodiment of the present invention, zirconia (ZrO 2) on a calcia (CaO) and magnesia process (MgO) is provided a calcia-stabilized magnesium parts zirconia (Ca-Mg-PSZ) employed with , A process of mixing calcia and magnesia partially stabilized zirconia and graphite (C), a process of forming a slag line portion surrounding a part of the outer wall of the nozzle body with a mixture of calcia and magnesia partially stabilized zirconia and graphite, Lt; RTI ID = 0.0 > of < / RTI >

The immersion nozzle may be manufactured by a nozzle forming mold including a rubber forming mold and a partitioning mold. First, particles of Al 2 O 3 -C forming the immersion nozzle body are filled in the rubber molding mold up to the lower end of the slag line portion, and a partitioning mold is installed according to the thickness of the slag line portion. Subsequently, a mixture of calcia and magnesia partially stabilized zirconia (hereinafter referred to as Ca · Mg-PSZ) and graphite is filled into the outside of the partition plate by the height of the slag line portion, and Al 2 O 3 -C .

The partition is then removed and the remainder is filled with particles of Al 2 O 3 -C. Next, a molded body is formed by applying pressure to the nozzle forming mold. Finally, after the nozzle forming mold is removed and heat-treated at a temperature of less than 1,000 ° C., an antioxidant is applied to the sintered body and dried to produce an immersion nozzle.

On the other hand, a binder may be added during the molding of the immersion nozzle. A thermosetting resin such as phenol resin may be used as the binder, and may be added so as to occupy 2 to 5 wt% of the immersion nozzle molding. If the binder is less than 2 wt%, the binding force of the immersion nozzle materials during molding is weak, and if the binder is more than 5 wt%, the water becomes too much and molding of the immersion nozzle becomes difficult. The binder is removed during the heat treatment of the formed body, and the immersion nozzle after the heat treatment is not included in the binder.

Thus, the slag line portion produced using the calcia-magnesia partially stabilized zirconia maintains a stable state at the tetragonal phase and the cubic phase. Therefore, since the stable phase is maintained even in the preheating or casting of the immersion nozzle, the volume change due to the phase change does not occur, so that the generation of cracks due to the volume change can be suppressed or prevented.

FIG. 9 is a schematic view showing the structure of the slag line portion of the immersion nozzle. FIG. 9 (a) is a diagram showing the structure of the slag line portion produced by using calcia partially stabilized zirconia in which calcia is stabilized in zirconia as a stabilizer, Fig. 9 (b) is a diagram showing the structure of a slag line portion produced by using calcia and magnesia partially stabilized zirconia in which calcia and magnesia are incorporated in zirconia as stabilizers.

9 (a), the slag line portion is formed by calcia deposits from calcia zirconia, and zirconia is phase-transformed from mono-phase to tetragonal or cubic phase due to solitary employment of calcia, it can be seen that cracks have occurred.

On the other hand, referring to FIG. 9 (b), it can be seen that the calcia and magnesia are not precipitated and remain solid in the zirconia, and cracks do not occur without phase transition of zirconia.

Accordingly, when the slag line portion is formed by using the zirconia which is employed together with the calcia and magnesia, the phase transition due to the temperature change is suppressed, so that the volume change due to the phase transition does not occur and the generation of cracks due to the volume change is suppressed or prevented can do.

Table 1 below shows experimental results for evaluating the physical properties and performance of the immersion nozzle manufactured by the embodiment of the present invention.

division Experimental Example 1 (Piece 1) Experimental Example 2 (Piece 2) Furtherance
(wt%) ZrO 2 (CaO · MgO) 80 (5) - ZrO 2 (CaO) - 80 (3) Graphite 17 17 Phenolic resin 3 3 Properties (G / cm3) 3.72 3.65 Apparent porosity (%) 15.8 16.5 Bending strength (kg / cm2) 100 97.5 Performance NSF polling index 90 100

Referring to Table 1, in Experimental Example 1, a specimen (hereinafter referred to as a specimen 1) prepared using calcia and magnesia partially stabilized zirconia in which calcia and magnesia were jointly incorporated in zirconia was used to measure the physical properties and the anti- Respectively. The specimen 1 was prepared by using 80 wt% of calcia and magnesia partially stabilized zirconia, 17 wt% of graphite and 3 wt% of a binder as a binder, and calcia and magnesia partially stabilized zirconia were prepared by using calcia and magnesia And 5% by weight of the calcia-magnesia partially stabilized zirconia was used. For reference, in the above description, the mixture of calcia and magnesia partially stabilized zirconia and graphite is set to 100 wt% and the binder is extrapolated. However, in this experiment, the calcia and magnesia partially stabilized zirconia, Weight%. However, in this experiment, the contents of calcia and magnesia partially stabilized zirconia and graphite and binder are within the above-mentioned range.

In Experimental Example 2, a test piece (hereinafter referred to as a test piece 2) prepared by using calcia zirconia solely containing 3 wt% of calcia in 80 wt% of zirconia was used to evaluate the physical properties and the NSR. At this time, 3 wt% of a phenol resin as a binder was added to the mixture of calcia zirconia and graphite.

The bulk specific gravity and apparent porosity of the specimens prepared in Experimental Examples 1 and 2 were measured by measuring the apparent porosity and specific gravity of the refractory by KS L3114 and the bending strength was measured in accordance with the method of testing the bending strength of the refractory by KSL 3110 .

As a result of evaluating the physical properties of the specimens 1 and 2 produced in Experimental Examples 1 and 2, the specimen 1 produced according to the embodiment of the present invention has a lower apparent porosity than the specimen 2, And the bending strength are high. The specimens produced by the manufacturing method of the present invention by repeated experiments were measured to have an apparent porosity of 16% or less, more preferably 13 to 16%, and a bending strength of 98 kg / cm 2 or more, more preferably 98 to 105 Kg / cm < 2 >. This indicates that the grain boundary of the calcia-magnesia partially stabilized zirconia forming the slag line portion does not have a phase change to the single crystal phase and maintains a stable tetragonal or cubic phase so that cracks due to the volume change do not occur. That is, since there is no crack in the slag line portion, the apparent porosity is measured to be low, and the bulk specific gravity and the bending strength are high as the apparent porosity is low.

In addition, the specimens 1 and 2 produced in Experimental Examples 1 and 2 were used to evaluate the resistance to abrasion. The NSF poling property was evaluated by indexing the degree of cracks generated in each specimen after applying a thermal shock by rapidly heating each specimen at about 1200 ° C at room temperature using a gas burner.

As a result, it was confirmed that the number of resorbable papers of Test Sample 1 prepared in Experimental Example 1 was improved by 10 or more, that is, by about 10% or more than that of Test Sample 2 prepared in Experimental Example 2.

In the case of manufacturing the slag line portion of the immersion nozzle by using the calcia and magnesia partially stabilized zirconia, which is obtained by employing calcia and magnesia together in the zirconia and securing the grain boundary stability, the immersion nozzle by the thermal shock, The occurrence of cracks in the slag line portion of the slag line can be suppressed and the anti-scrubbing property can be improved. Further, when the continuous casting process is performed using the immersion nozzle of the present invention, it is possible to prevent the slag line portion of the immersion nozzle, that is, the slurry line portion of the immersion nozzle, from being cracked or peeled and to maintain the cleanliness of the molten steel, .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein. Those skilled in the art will appreciate that various modifications and equivalent embodiments may be possible. Accordingly, the technical scope of the present invention should be defined by the following claims.

10: Tundish 20: Stopper
30: sliding plate 40: immersion nozzle
41: nozzle body 42: slag line part
43: discharge port 50: mold
60: molten steel 61: cast steel
62: Slag

Claims (9)

A nozzle body having an inner work capable of moving molten steel;
A slag line portion surrounding at least a part of the outer wall of the nozzle body and in contact with the slag; And
Wherein said molten steel has a discharge port through which said molten steel can move outwardly from said inner work,
Wherein the slag line portion comprises calcia (CaO) -magnesia (MgO) partially stabilized zirconia. The method according to claim 1,
The partially stabilized zirconia of CaO and MgO is solubilized in an amount of 3 to 10 wt% based on the total weight of the partially stabilized zirconia of CaO and MgO. The method of claim 2,
The partially stabilized zirconia of CaO and MgO is composed of 85 to 97% by weight of zirconia, 2 to 8% by weight of calcia and / or zirconia, based on the total weight of the partially stabilized zirconia of CaO and MgO, 1 to 7% by weight of magnesia. The method of claim 3,
The CaO-MgO partially stabilized zirconia is 70 to 85 wt% of the slag line portion. The method of claim 4,
Wherein the slag line portion further comprises graphite (C)
Wherein the graphite is 15 to 30 wt% of the slag line portion. The method of claim 5,
The calcined zirconia (CaO) -magnesia (MgO) partially stabilized zirconia has a tetragonal and cubic top. The method according to any one of claims 1 to 6,
Wherein the nozzle has an apparent porosity of 16% or less. A step of mixing calcia and magnesia partially stabilized zirconia in which calcia (CaO) and magnesia (MgO) are solid-solved in zirconia (ZrO 2 ) and graphite (C);
Molding a slag line portion surrounding a part of the outer wall of the nozzle body with a mixture of the calcia-magnesia partially stabilized zirconia and graphite; And
And heat treating the molded body in which the slag line portion is molded. The method of claim 8,
Wherein the binder is added in the step of mixing the calcia and magnesia partially stabilized zirconia with the graphite (C).
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113649538A (en) * 2021-08-19 2021-11-16 宝武集团鄂城钢铁有限公司 Automatic slag line changing system of slab caster based on molten steel temperature control
EP3827912B1 (en) * 2019-11-26 2022-03-30 Refractory Intellectual Property GmbH & Co. KG An exchangeable nozzle for a nozzle changer system, a method for manufacturing such a nozzle, a nozzle changer system comprising such a nozzle and a tundish comprising such a nozzle changer system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100258131B1 (en) 1997-09-06 2000-06-01 한종웅 Nozzle for continuous casting

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100258131B1 (en) 1997-09-06 2000-06-01 한종웅 Nozzle for continuous casting

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3827912B1 (en) * 2019-11-26 2022-03-30 Refractory Intellectual Property GmbH & Co. KG An exchangeable nozzle for a nozzle changer system, a method for manufacturing such a nozzle, a nozzle changer system comprising such a nozzle and a tundish comprising such a nozzle changer system
CN113649538A (en) * 2021-08-19 2021-11-16 宝武集团鄂城钢铁有限公司 Automatic slag line changing system of slab caster based on molten steel temperature control

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