TWI421225B - A refractory, a continuous casting nozzle using the refractory and a method for manufacturing the continuous casting nozzle, and a continuous casting method using the continuous casting nozzle - Google Patents

Description

Refractory, nozzle for continuous casting using the refractory, method for producing the same, and continuous casting method using the nozzle for continuous casting

The present invention relates to a refractory for suppressing or preventing adhesion from a filler of a molten steel ("suppression or prevention" hereinafter referred to as "prevention"), a continuous casting nozzle using the refractory, and a nozzle for the continuous casting. A method, and a continuous casting method using the nozzle for continuous casting.

The nozzle for continuous casting which is the object of the present invention is a nozzle used in continuous casting of general molten steel, in particular, an impregnation nozzle. It is typically a tubular refractory structure having an inner hole through which molten steel passes in the axial direction, but other irregular shapes may also be objects.

In the present invention, the "axial direction" means the longitudinal direction of the nozzle for continuous casting, and the "tubular shape" means a shape having an inner hole in the axial direction regardless of the cross-sectional shape perpendicular to the axial direction. That is, the cross-sectional shape in the direction perpendicular to the axial direction is not limited to a circular shape, and may be an elliptical shape, a rectangular shape, a polygonal shape, or the like.

In recent years, along with high-class steel and the like also enable the Al ₂ O ₃ and other non-metallic material is interposed in the molten steel (the present invention, a non-metallic dielectric spacers, Al ₂ O ₃ dielectric spacers, the dielectric spacers Addition, etc., in the inner surface of the continuous casting nozzle, the adhesion of the substrate centering on Al ₂ O ₃ or the clogging of the inner hole is one of the major factors determining the life of the nozzle for continuous casting.

In such a situation, the demand for high durability of the continuous casting nozzle is prevented by preventing adhesion or clogging of the inner surface of the non-metallic spacer or the like. Therefore, in order to prevent adhesion of a component component such as Al ₂ O ₃ from the molten steel to the inner hole surface, various types of refractory layers on the inner hole surface side of the continuous casting nozzle have been proposed.

For example, Patent Document 1 discloses a nozzle for continuous casting which does not contain a carbon component at least in a hole portion of a nozzle and/or a portion in contact with a molten steel, and has 5 to 10% by weight of SiO ₂ and 90 to 95% by weight of Al. ₂ O ₃ chemical composition, and the main mineral phase is composed of mullite and corundum and/or β-Al ₂ O ₃ Al ₂ O ₃ -SiO ₂ refractories.

However, such a carbon-free refractory material is extremely resistant to thermal shock, and is particularly likely to be damaged by thermal shock such as when molten steel is injected. Further, even if the carbon component is not contained, such an Al ₂ O ₃ -SiO ₂ -based refractory material cannot sufficiently prevent the adhesion of the spacer centering on Al ₂ O ₃ or the clogging of the inner pores.

Therefore, many proposals have included a large amount of CaO component which is likely to generate a low-melt reaction with a matrix containing Al ₂ O ₃ as a center material in the material of the refractory layer on the inner hole surface side, thereby preventing the spacer, etc. Adhesion or occlusion of the inner hole.

For example, Patent Document 2 discloses that an inner liner comprising a composition of 40 to 90% by weight of CaO, 0 to 50% by weight of MgO, and 0 to 20% by weight of C is disposed on the inner hole of the nozzle. However, in such an inner liner layer, especially when the CaO content is large, since CaO is easily hydrated and exists as free limestone, it is difficult to put it into practical use due to the destruction of the nozzle due to its digestion. Further, such a composition such as CaO has a large thermal expansion property, and thermal expansion of the inner liner formed by the composition causes destruction of the outer body layer, that is, the continuous casting nozzle itself.

For the problem of such CaO, for example, Patent Document 3 discloses that calcium cyanate clinker containing CaZrO ₃ as a main component containing 16 to 35% by weight of CaO is 20 to 95% by weight, and graphite is 5 to 50% by weight. In the continuous casting nozzle containing ZrO ₂ -CaO, which is composed of %, etc., Patent Document 4 discloses that zirconium coal slag containing 3 to 35% by weight of CaO is added to the inner surface layer portion (the mineral composition thereof is contained). Anti-adhesion layer made of clay of one or two kinds of cubic ZrO ₂ , CaZrO ₃ ) 40 to 85% by weight, 10 to 30% by weight of graphite, 1 to 15% by weight of cerium oxide and 1 to 15% by weight of magnesium oxide Casting nozzle. Since CaO is not present as free limestone, this material exists as a mineral having a crystal structure such as ZrO ₂ .

However, in the actual continuous manufacturing operation of the refractory material composed of the components, the effect of preventing the adhesion of the spacer component such as Al ₂ O _{3 to} the inner hole surface is small, and the durability of the continuous casting nozzle cannot be sufficiently ensured. . Further, although the digestive problem can be solved, the thermal expansion property cannot be reduced to the same extent as the Al ₂ O ₃ -graphite refractory of the main continuous casting nozzle body portion located outside the inner hole side layer, and the unit is integrally provided. The damage caused by the thermal shock of the nozzle for continuous casting cannot be sufficiently prevented.

It is necessary to provide a layer having a large thermal expansion property on the side of the inner hole to improve the thermal shock resistance of the structural surface of the nozzle for continuous casting. For example, Patent Document 5 discloses a CaO nozzle formed of a refractory material having an apparent porosity of 50% or less of CaO, an external base material nozzle, and a CaO nozzle on the inner hole side and a mother thereof on the outer side. A casting nozzle corresponding to a gap that replaces the thermal expansion of the CaO nozzle is provided between the material nozzles.

Therefore, when such a special structure in which a gap or the like is provided between the inner hole side layer and the outer peripheral side layer, it is difficult to provide a continuous casting operation or the like as a general one body molded body. Further, there is a problem that the risk of damage or breakage of the nozzle for continuous casting becomes high due to scratching or peeling of the inner hole side layer.

Further, Patent Document 6 discloses a continuous casting nozzle which can reduce the amount of adhesion of a non-metallic spacer to a nozzle and prevent clogging, and is used as an inexpensive manufacturer to use Al ₂ O ₃ in whole or in part. 20 to 80% by weight, graphite is 10 to 45% by weight, SiO ₂ is 1 to 20% by weight, CaO is 0.1 to less than 3% by weight, or oxide of Group IIa other than Ca is 0.1 to 5% by weight. A nozzle for continuous casting of refractory.

However, the refractory of this composition is produced only by the reaction of Al ₂ O ₃ , SiO ₂ and CaO, but is formed in the entire refractory containing these components. That is, although SiO ₂ volatilizes and moves, CaO or Al ₂ O _{3 does} not move from the position where it originally existed, but forms a melt of Al ₂ O ₃ -CaO system in the structure, and the SiO ₂ component dispersed in the structure. Since it is absorbed into the melt and further liquid-phased, CaO-Al ₂ O ₃ -SiO ₂ is stabilized in the structure, so that it is difficult to form a film having a high coverage on the running surface side. Further, after the start of casting, the supply of the fire-resistant components from the Al ₂ O ₃ and SiO ₂ aggregates toward the melt side increases the amount of the low-melt formed, which is in terms of heat strength or corrosion resistance. problem.

That is, it is impossible to form a sufficient low-melt between the Al ₂ O ₃ spacers in contact with the running surface with this composition, and the adhesion preventing effect of the Al ₂ O ₃ spacer is extremely limited. Therefore, as time passes, the Al ₂ O ₃ spacer is easily attached in a short time. The oxidation of Al in the molten steel by SiO (gas) released from the running surface also tends to promote the formation and adhesion of Al ₂ O ₃ . For this purpose the composition of Al ₂ O ₃ -SiO ₂ -CaO-based materials can not be used as universal attachment material difficult.

When a CaO-based refractory is disposed on the inner bore side, there are many problems such as structure, manufacture, operation, performance, and the like, and it is a problem that is largely unsolved in the industry by overcoming the need for labor or cost.

[Previous Technical Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 10-128507

[Patent Document 2] Japanese Patent Publication No. 01-289549

[Patent Document 3] Japanese Patent Publication No. 02-023494

[Patent Document 4] Japanese Patent Publication No. 03-014540

[Patent Document 5] Japanese Patent Publication No. 07-232249

[Patent Document 6] JP-A-2001-179406

The problem to be solved by the present invention is to prevent Al ₂ O ₃ spacer from adhering to the nozzle used, especially in a continuous casting operation of a steel such as Al-killed steel which is liable to cause nozzle clogging. Wait and prevent blocking. Moreover, it is possible to solve the problem of occurrence of cracking due to high expansion inherent in the CaO-containing refractory material proposed by the prior art, such as prevention of adhesion of an Al ₂ O ₃ spacer or the like, and the like. The refractory containing CaO is cheaper and easier to manufacture, and a refractory of a nozzle having a structure that is more stable than a split structure (for example, a structure in which the inner hole body and the system are formed by the same member) can be obtained even in operation. And a nozzle for continuous casting using the refractory, a nozzle for continuous casting thereof, and a casting method using the nozzle for continuous casting.

The present invention is as follows.

[Patent No. 1 of the scope of application]

A refractory material containing 0.5% by mass or more of CaO component, each of which is 0.5% by mass or more, or a total amount of 0.5% by mass or more of B ₂ O ₃ and R ₂ O (R is Na, K, Li) In one case, 50% by mass or more of Al ₂ O ₃ , 8.0% by mass or more, and 34.5 % by mass or less of free carbon, and the total of CaO, B ₂ O ₃ and R ₂ O is 1.0% by mass or more and 15.0% by mass or less. The mass ratio CaO/(B ₂ O ₃ + R ₂ O) is in the range of 0.1 or more and 3.0 or less.

[Scope 2 of the patent application]

The scope of the refractory patent, Paragraph 1, after which baking room temperature ventilation rate of 0.4 × 10 ^-3 to 4.0 × 10 ^-3 cm ² at the non-oxidizing atmosphere at 1000 ℃ / (cmH ₂ O‧sec) of range.

[Scope 3 of the patent application]

A refractory according to claim 1 or 2, wherein the ZrO ₂ content is 6% by mass or less (including zero).

[Scope 4 of the patent application]

A continuous casting nozzle in which a refractory according to any one of claims 1 to 3 is disposed on a part or all of a surface in contact with a molten steel.

[Scope 5 of the patent application]

The continuous casting nozzle of claim 4, wherein the refractory material according to any one of claims 1 to 3 is disposed on a part or all of the surface in contact with the molten steel. It is formed in a single body structure directly joined to a layer other than the refractory material adjacent to the layer.

[Scope 6 of the patent application]

A method for producing a nozzle for continuous casting, which is a method for producing a nozzle for continuous casting in which a refractory according to any one of claims 1 to 3 is disposed on a part or all of a surface in contact with a molten steel, which comprises :

Part or all of a layer consisting of the refractory material of any one of claims 1 to 3 in the nozzle for continuous casting, and the clay supplied thereto, and supplied to be formed adjacent to the layer The clay of the layer formed other than the refractory is adjacent to the same pressure and is a step of forming a molded body having an integral structure.

[Application No. 7]

A continuous casting method for arranging a continuous casting nozzle of a refractory according to any one of claims 1 to 3 to prevent Al ₂ O ₃ spacers from being used on a part or all of the surface in contact with the molten steel. The spacer is attached to the wall surface of the continuous casting nozzle.

In the present invention, the "R" of "R ₂ O" is any of Na, K, and Li as described above, and thus "R ₂ O" is any of Na ₂ O, K ₂ O, and Li ₂ O. However, the "R ₂ O" is not limited to any one of Na ₂ O, K ₂ O, and Li ₂ O, and may be plural kinds in combination. When a plurality of types are coexisted, all of them may be integrally processed.

The chemical component values in the present invention are based on the measured values of the samples after heat treatment in a non-oxidizing atmosphere at 1000 °C.

The details are described below.

The present invention basically forms a dense viscous film on the running surface of the refractory material in contact with the molten steel, and prevents the adhesion of the Al ₂ O ₃ spacer by continuously forming the film and maintaining it.

The dense viscous film layer includes a coating layer of a molten slag layer, and the film layer on the refractory surface is referred to as a "slag-containing layer in a semi-molten state" or simply as a "slag coating layer" in the present invention.

In the semi-molten slag coating layer of the present invention, in the mechanism of Al ₂ O ₃ spacer removal, it is important to be a dense viscous liquid phase.

The slag coating layer having a dense viscous liquid phase is a slag phase which exists on the running surface of the refractory, that is, a film-like layer between the molten steel and the refractory, and the inside of the slag phase contains CaO and Al. part of the molten degree of movement of the component ₂ O _3, and the molten slag layer can be said to be a state not easy to maintain the degree of viscosity of the effluent stream of the molten steel. Further, in the present invention, the slag is preferably a structure including a refractory portion in a molten state, and the molten phase portion may contain a glass phase or a melt other than the glass phase, and may also contain a glass which does not constitute a glass or It is in a state of being a crystal grain or the like in a molten state.

The refractory of the present invention is a carbon-containing refractory which has a reducing atmosphere in the refractory structure. Either or both of B ₂ O ₃ and R ₂ O, which are constituents of CaO and a low-melt component in the refractory, are dispersed and present in a specific amount. The slag coating layer is formed on the surface of the refractory by forming a viscous molten slag phase by reacting the temperature grade of the molten steel with the refractory aggregate mainly composed of Al ₂ O ₃ to prevent the partition of Al ₂ O ₃ or the like. Attached.

By the slag coating layer, the Al ₂ O ₃ spacer is prevented from directly contacting the surface of the refractory, and the unevenness of the surface of the refractory is smoothed, and the minute turbulence of the molten steel near the outermost surface of the refractory is suppressed ( The effect of molten steel eddy). The suppression of the eddy current of the minute molten steel near the outermost surface of the refractory becomes a collision between the inertial force of the eddy current of the molten steel on the surface of the refractory by suppressing the non-metallic spacer of Al ₂ O ₃ or the like suspended in the molten steel. As a result, adhesion of the Al ₂ O ₃ spacer was suppressed.

Further, the dense and viscous slag coating layer on the refractory running surface is also high in the coverage of the refractory surface or almost no open pores in the coating layer itself, so that the refractory component such as C or Si can be suppressed from melting. in steel melting, adhering phenomena becomes possible to prevent Al ₂ O ₃ and the like via the spacers. This system utilizes the following mechanism. If C or Si or the like of the refractory component in direct contact with the refractory is melted into the molten steel, the surface tension gradient of the molten steel is generated along the molten steel near the outermost surface of the refractory (the solute concentration gradient) The surface tension in the molten steel near the refractory becomes small). On the other hand, the internal filler of the molten steel such as Al ₂ O ₃ tends to move toward the lower surface tension of the molten steel, so that the Al ₂ O ₃ adhesion phenomenon near the outermost surface of the refractory is promoted.

Furthermore, in the presence of the CaO-based molten slag coating layer at the operating interface of the molten steel/refractory, there is also an effect of desulfurization reaction in the molten steel due to CaO, accompanied by the vicinity of the surface of the refractory (refractory-melting At the steel interface, the sulfur solute concentration is lowered, and the surface tension of the molten steel near the surface of the refractory body tends to increase, so that the adhesion of Al ₂ O ₃ is suppressed.

In order to form a dense and viscous slag coating layer at the interface between the refractory and the molten steel, it is necessary to suppress the components constituting the slag phase (hereinafter also referred to as "slag-forming components") and the components in the refractory structure. The reaction of the refractory composition, on the other hand, is necessary to form a slag coating on the refractory running surface (meaning the interface with the molten steel).

The inventors of the present invention investigated the influence of the slag components on the Al ₂ O ₃ adhesion phenomenon at a molten steel flow rate by a spin test in a molten steel, and found the following findings.

1. When the refractory is tested by the rotation test in molten steel, when a slag coating layer having a coverage of 50% or more and a thickness of 0.1 mm or more and a semi-molten state is formed on the surface of the refractory, the continuous production of steel can be remarkable. The adhesion of Al ₂ O ₃ is suppressed.

2. The refractory material for obtaining the slag coating layer in the spin test method of the molten steel contains 0.5% by mass or more of CaO component, each of which is 0.5% by mass or more or a total amount of B ₂ of 0.5% by mass or more. O ₃ and R ₂ O (R is any one of Na, K, and Li), 50% by mass or more of Al ₂ O ₃ , 8.0% by mass or more, and 3.45% by mass or less of free carbon, and CaO, B ₂ O ₃ and The total of R ₂ O is 1.0% by mass or more and 15.0% by mass or less, and the mass ratio CaO/(B ₂ O ₃ + R ₂ O) is in the range of 0.1 or more and 3.0 or less.

Most of the prior art, along with the casting time, the adhesion prevention effect of the Al ₂ O ₃ and the like is reduced. The reason is that the composition of the prior art refractory is only based on the composition of the refractory near the surface in contact with the molten steel, and the low melting is not caused by the reaction with Al ₂ O _{3 ,} and the loss caused by the molten steel flow is the main effect. . That is, a component (CaO or the like) which reacts with the Al ₂ O ₃ spacer in the molten steel near the surface of the refractory is consumed over time, or a solid reaction layer is formed on the surface, and the solid phase is formed and melted. The reaction of the Al ₂ O ₃ spacer in the steel is significantly reduced or unreacted. In such a prior art, in order to obtain an Al ₂ O ₃ adhesion preventing effect in a stable or long time, it is necessary to add a relatively large amount of a reactive component such as CaO, but in this case, it coexists with Al ₂ O ₃ aggregate or the like. There is a problem that the strength of the other refractory components is caused by the reaction, and the strength is lowered, the thermal shock resistance is lowered, and the corrosion resistance is lowered.

In the present invention, the adhesion preventing effect of the Al ₂ O ₃ spacer can be sustained not only at the start of casting but also for a short time from the start of casting, and can be continued for a long time with little reduction. That is, in the feature of the present invention, the concentration of volatile oxides (B ₂ O ₃ and R ₂ O) at the molten steel operating interface in a reducing atmosphere at a molten steel temperature level is utilized to cause the volatilization. oxide aggregate and the reaction Al ₂ O ₃ component, is formed continuously with slag containing molten state of the dense and thick layer of slag covering molten steel at the interface of the refractory, and to prevent the steel The nozzle is blocked by the spacer.

Describe it in detail.

For example, a carbonaceous refractory disposed at a portion where the molten steel passes at a rapid speed in a casting nozzle is continuously exposed to a negative pressure on the outermost surface (inner wall surface) of the refractory which is in contact with the molten steel during casting. In these environments, when the B ₂ O ₃ and R ₂ O components which are known to have higher volatility (vaporization) than the SiO ₂ component are present in the carbon-containing refractory structure, the volatile oxides rapidly approach The molten steel/refractory interface on the negative pressure side moves. (The SiO ₂ component has a lower volatilization energy than these components, but coexists with the ability to promote film formation. However, since the SiO ₂ component suppresses low melting in the structure, it is preferably used in a particle size of 0.21 mm or more). As a result of the concentration of volatile components at the molten steel/refractory interface, a molten slag phase is formed at the molten steel/refractory interface.

The molten slag phase preferentially incorporates the CaO component of the alkaline component dispersed in the matrix or the B ₂ O ₃ component and the R ₂ O component which are volatilized and concentrated on the running surface, and continuously forms CaO-B ₂ O ₃ rich in CaO. A molten slag phase of the CaO-R ₂ O system or the CaO-B ₂ O ₃ -R ₂ O system.

One part of the molten slag phase reacts with the Al ₂ O ₃ aggregate at the operating interface to form a dense and viscous film-like layer containing the molten slag phase between the molten steel and the refractory, that is, the slag coating Floor.

a film-like slag coating layer having a viscous phase containing a molten phase formed on the running surface while maintaining a moderate viscosity near the molten steel temperature, and the molten steel is obtained by the smoothing action of the refractory running surface and the protective film action The spacer particles of Al ₂ O ₃ or the like are not fixed to the refractory and flow out in the molten steel. On the other hand, in the present invention, the concentration of the volatile component does not move on the running surface side and the formation of the slag coating layer continuously during the casting (operation). By the formation of the continuous slag coating layer, unlike the prior art, the refractory of the present invention can continuously exhibit the adhesion preventing effect of the Al ₂ O ₃ spacer over a long period of time.

Hereinafter, each component and each element will be described.

CaO has the effect of reacting with the sulfur component from the molten steel in the slag coating layer on the surface of the refractory material in contact with the molten steel to lower the free sulfur concentration in the molten steel at the operation interface. If the concentration of free sulfur in the molten steel is lowered, the surface tension of the molten steel tends to increase. By such a reaction, the surface tension in the molten steel near the surface of the refractory of the present invention is increased. Since the non-metallic spacer of Al ₂ O ₃ or the like moves toward the surface tension of the molten steel as described above, the surface tension of the molten steel near the surface of the refractory due to the change in the sulfur concentration is increased, whereby Al ₂ can be made. O _3, etc. interposed non-metallic contacting surface of the refractory reduced frequency. And CaO forms a low-melt by reacting with Al ₂ O ₃ , and also has the function left in the molten steel. CaO is also a component that lowers the viscosity of the slag phase, and particularly has an effect of increasing the temperature of the molten steel and the reactivity of the Al ₂ O ₃ aggregate, and also functions to form a viscous slag phase. Due to such an action, the amount of CaO must be 0.5% by mass or more in the refractory.

CaO is also stable in a reducing atmosphere, and does not move to the surface of the refractory which is in contact with the molten steel, as the volatile components such as B ₂ O ₃ or R ₂ O are vaporized in the refractory structure. Therefore, in the slag phase in the semi-molten state of the running surface, adhesion of Al ₂ O ₃ can be effectively suppressed. That is, if CaO is in the slag phase in a semi-molten state, it becomes movable, and in this slag phase, it reacts with a spacer such as Al ₂ O ₃ or S (sulfur) derived from molten steel, and contributes to Improve its reactivity. When the CaO component is less than 0.5% by mass, the above functions cannot be sufficiently obtained.

B ₂ O ₃ and R ₂ O are components (slag-forming components) constituting the slag phase, and by either or both of them, a coating layer can be formed from the slag phase in the viscous semi-molten state at the operation interface. Since these components are in a molten state at a lower temperature than other components, it contributes to the formation of a film immediately after the surface of the refractory is brought into contact with the molten steel. When the amount of CaO is not contained, the slag is formed by other components, and it is difficult to maintain a film capable of sufficiently suppressing adhesion of a spacer such as Al ₂ O ₃ in the initial stage of casting. Further, the vapor pressure of B ₂ O ₃ and R ₂ O at the temperature of the molten steel is also much higher than that of the SiO ₂ component, and is particularly volatile in a reducing atmosphere, and can be easily moved in the refractory structure by volatilization.

On the other hand, the slag coating layer in the semi-molten state of the refractory running surface (the surface in contact with the molten steel, the same applies hereinafter) is not only reacted with the interlayer material such as Al ₂ O ₃ from the molten steel but also due to melting. The mechanical wear caused by the steel flow gradually disappears. The volatile B ₂ O ₃ and R ₂ O components are continuously moved toward the reduced refractory running surface during casting (work).

The B ₂ O ₃ and R ₂ O components moving toward the refractory running surface side are concentrated at the refractory operation interface (the interface with the molten steel, hereinafter also simply referred to as "operation interface"), and react with the CaO in the group, and The slag is phased. The reactivity of the slag phase formed at the operation interface with the surrounding fire-resistant aggregate (mainly Al ₂ O ₃ ) is increased to form a slag layer of viscous fire resistance.

Thus, the B ₂ O ₃ and R ₂ O components continuously move toward the refractory running surface due to volatilization, thereby playing a role of continuously forming a viscous slag phase film on the refractory running surface.

In order to continuously form the slag coating layer in the semi-molten state during the initial stage of casting and during the duration of casting (work), the respective amounts of B ₂ O ₃ and R ₂ O or both may be taken before the amount of CaO is present. The total amount must be 0.5% by mass or more. When the amount of each of B ₂ O ₃ and R ₂ O or the total amount of both is less than 0.5% by mass, the relative amount with respect to the other refractory aggregate is too small, and the slag phase which is a film in a semi-molten state cannot be formed. It is also difficult to make these uniform dispersions and continuous movements. Further, the optimum values of the amounts of CaO, B ₂ O ₃ and R ₂ O may be determined in accordance with the spin test method in the molten steel in accordance with the individual operating conditions.

The total amount of CaO, and either B ₂ O ₃ and R ₂ O or a combination of both (CaO and B ₂ O ₃ , or CaO and R ₂ O) The total amount or the total amount of CaO, B ₂ O ₃ and R ₂ O must be 1.0% by mass or more, and the upper limit of the above must be 15.0% by mass or less. When the total amount of CaO and B ₂ O ₃ and R ₂ O is more than 15.0% by mass, the molten slag is greatly reduced in the refractory structure in the temperature range of the molten steel temperature level. Since it is carried out, problems such as a decrease in the degree of refractoriness, an increase in the melt loss, and a decrease in strength are likely to occur.

Further, in order to form a dense thick slag on the operation surface of the refractory coating layer is any one of, CaO, and B ₂ O ₃ and R ₂ O or of an addition to the total amount of both must be 1.0 mass%, 15 mass The mass ratio CaO/(B ₂ O ₃ +R ₂ O) must be in the range of 0.1 or more and 3.0 or less, in addition to % or less.

In other words, the mass ratio may be referred to as a non-volatile component/volatile component with respect to the component (slag-forming component) constituting the slag phase of the present invention. In the present invention, as described above, in order to form and maintain a viscous slag phase, it is an important factor to continuously supply a volatile component to the running surface. Therefore, the balance between the non-volatile component and the volatile component is optimized, and the effect of the present invention is more sure, and the effect is high and effective. When the mass ratio is less than 0.1, since the CaO component which is stabilized in a reducing atmosphere is relatively small, the chemical component of the phase concentrated on the running surface is mainly a volatile oxide, so that the low-viscosity slag phase cannot be obtained. It is stable at high temperatures. Therefore, it is difficult to form a slag coating layer having a high coverage on the running surface, which is a result of poor adhesion inhibition effect of the Al ₂ O ₃ spacer. On the other hand, when the mass ratio exceeds 3.0, the CaO component which is stable in a reducing atmosphere is relatively large, but since the slag phase formed by concentration becomes a low-viscosity slag coating layer, it is due to the molten steel flow rate. Since the slag which is liable to remain has a large phase change, it is difficult to form a continuous slag coating layer for a long period of time. Therefore, it is a result of poor adhesion inhibition effect of the Al ₂ O ₃ spacer.

B ₂ O ₃ and R ₂ O are continuously supplied to the running surface of the refractory, and in order to continuously and efficiently form a dense viscous slag phase or a slag coating layer in a semi-molten state, B ₂ O as a volatile component is preferred. _{3. The} R ₂ O component is dispersed in the refractory matrix. When the volatile component is contained in the matrix, volatilization of the oxide which is a volatile component becomes easy, and it is easy to cause component movement in the tissue.

The term "matrix" as used in the present invention means a carbon mainly composed of carbon as a binder in a refractory structure and a refractory material having a particle diameter of about 0.21 mm or less, and the aforementioned volatile component or regardless of the particle diameter. When a CaO or the like is integrated or agglomerated (hereinafter referred to as "melting and other organization"), it is a structural part of a structure including a fusion thereof, and a refractory aggregate having a particle diameter of more than about 0.21 mm ( Hereinafter referred to as "refractory" portion of the refractory structure.

By dispersing in the matrix, it means that regardless of the location in the matrix (any position), it exists with almost the same probability, meaning that the coarse particles themselves are not in a compound or mechanically constrained state, but The refractory structure except the coarse particles is substantially uniform (the content difference expressed by the percentage of probability is about 30% or less).

In order to keep the refractory structure under a reducing atmosphere, it is necessary for the refractory to contain free carbon. Here, as the free carbon, a component other than carbon is excluded from the compound, regardless of the amorphous or crystalline form, and the carbon monomer exists regardless of whether or not the compound is mixed with impurities in the particle or the continuous structure. Specifically, it means a binder derived from a resin or an asphalt, graphite, carbon black or the like.

The refractory of the present invention is different from a refractory containing a large amount of CaO mainly composed of perirace or zirconate having high thermal expansion, and is composed of a relatively low thermal expansion property of Al ₂ O ₃ . . Therefore, in order to obtain thermal shock resistance, it is possible to ensure thermal shock resistance with the same amount of graphite as the Al ₂ O ₃ -graphite refractory of the main portion of the nozzle for general continuous production. On the other hand, in order to attach a function of preventing adhesion of a spacer such as Al ₂ O _{3 to} the running surface on the inner hole side, in particular, a refractory layer mainly composed of CaO is disposed, and the refractory itself is included. The graphite improves the thermal shock resistance, and it is necessary to have a large amount of graphite, and also has disadvantages such as deterioration of corrosion resistance or wear resistance, and it is practically impossible. Compared with these systems, the refractory of the present invention relatively reduces the amount of graphite because the main composition of the refractory becomes Al ₂ O ₃ which is relatively lower in thermal expansion than CaO.

That is, the refractory of the present invention contains 8.0% by mass or more and 34.5% by mass or less of free carbon. The free carbon refers to the total of carbon as the aggregate particles and carbon as the binder.

The carbon as the aggregate is mainly a graphite material, and by adding it as a filler between the carbonaceous bonding structures, the strength of the structure can be improved, the thermal conductivity can be improved, and the thermal shock resistance can be improved by reducing the thermal expansion rate. . In addition, the carbonaceous aggregate particles (which may be considered as a part of the carbon of the binder) are present between the oxides and the like, and have an effect of suppressing sintering of the oxide or a low melting reaction, and may be expected to be in the case of casting. Quality stability. Further, graphite and carbon black may be used together in part.

The refractory of the present invention can be applied only to the inner surface of the nozzle for continuous casting, and the amount of carbon of the aggregate particles (graphite aggregate or the like) in this case is preferably 7% by mass or more. Moreover, the refractory of the present invention can also be applied to the main body portion of the nozzle for continuous casting. In this case, the aggregate particles are preferably 18.0% by mass or more and 33.5% by mass or less. When it is less than 18.0% by mass, it is difficult to ensure sufficient resistance to thermal shock at the time when the molten steel is subjected to steel, for example, in a low state from a preheating temperature of about 1000 °C. If it exceeds 33.5 mass%, it is easy to be damaged by the abrasion of the molten steel flow, and in addition to shortening the durability time of the nozzle for continuous casting, local loss due to the bias flow of the molten steel is likely to occur.

The carbon as the binder accounts for the strength of the refractory itself, and the structure maintains the morphology and mainly imparts resistance to damage by thermal shock. The carbon as the binder is preferably obtained by fixing a large amount of carbon, a carbon-bonded resin, pitch, coke, or the like, mainly at a high temperature (in a non-oxidizing atmosphere of about 1000 ° C or higher). The carbon as the binder is preferably 1.0% by mass or more. If it is less than 1.0% by mass, it is difficult to obtain sufficient strength to maintain the structure in which the aggregates are bonded to each other by carbon. Moreover, in the case where the thickness of the refractory of the present invention is relatively small (for example, about 10 mm or less), the initial strength is preferably increased, and the like, and it is more preferably 2.0% by mass or more. The upper limit is preferably 5.0% by mass or less. When the content is more than 5.0% by mass, the strength of the carbon-bonded structure is sufficient, but the thermal shock resistance is liable to be lowered or the yield of the product (the nozzle for continuous casting using the refractory of the present invention) is lowered, which is not preferable. The amount of carbon of the binder may be changed or determined depending on the individual operation or the conditions at the time of production in the above range.

In the present invention, the state of the specific slag coating layer in the spin test method in the molten steel is used as a criterion for evaluating the effects of the present invention. The state of slag coating is practically impossible to directly measure and quantify in the operation.

Therefore, in the present invention, the spin test in molten steel is used as a test method for a laboratory for estimating the state of a molten steel coating layer in an operation. Therefore, a slag coating layer having a coverage of 50% or more and a thickness of 0.1 mm or more (which can be regarded as a semi-molten state during heating) is formed on the surface of the refractory for the test sample, and it is confirmed whether work can be obtained. The adhesion preventing effect of the spacer such as Al ₂ O ₃ in the middle.

Next, the spin test method in molten steel will be described.

Fig. 1 shows a state in which the holder 2 of the test object (hereinafter referred to as "sample") 1 which has been processed into a specific shape is immersed in the molten steel 3 in the crucible 4 in the lower portion. The test material 1 is provided in four rectangular parallelepiped bodies, and is respectively fixed on the four sides of the lower portion of the holder 2 of the quadrangular prism. The sample 1 is inserted into the recess provided in the holder 2 of the square post through the mortar, and can be pulled out after the end of the test. The upper shaft of the holder 2 is connected to a long shaft of a rotating shaft (not shown) as a rotating shaft to be rotatably held. Further, the holder 2 was formed into a square having a side length of 40 mm with respect to the long axis and a length of 160 mm in the longitudinal direction, and was made of zirconia-carbonaceous refractory. The exposed portion of the sample 1 exposed from the holder 2 was 20 mm high, 20 mm wide, and 25 mm long. Further, the lower end surface 1a of the sample 1 was attached to a position 10 mm away from the lower end surface 2a of the holder 2.

坩埚4 is a cylindrical refractory material having an inner diameter of 130 mm and a depth of 190 mm. In this crucible 4, the molten steel 3 is retained, and the crucible 4 is housed in the high frequency induction furnace 5, and the molten state and temperature of the molten steel 3 can be controlled. The immersion depth of the holder 2 in the molten steel 3 is 50 mm or more. Although not shown, it can be capped on top.

In the molten steel, the rotation test is performed on the molten steel 3 to keep the sample 1 for 5 minutes, and then in the low carbon aluminum deoxidized steel of the molten steel 3, the sample 1 is immersed to a distance of 50 to 100 mm from the surface of the molten steel. The outermost peripheral surface of the sample 1 was rotated at an average speed of 1 m/sec. In the test, aluminum was added to the molten steel to maintain the oxygen concentration below 50 ppm, and the temperature was maintained in the range of 1550 to 1570 °C. After 3 hours, the sample 1 was pulled up, and the sample to be tested was cooled with a holder 2 in a non-oxidizing atmosphere in a non-oxidizing atmosphere, and the size of the sample 1 was measured.

The measurement of the adhesion or the loss rate is as shown in Fig. 2. The sample 1 after the end of the test is removed from the holder, and the horizontal plane in the direction perpendicular to the rotation axis (the surface in the circumferential direction) is at the height of the sample. Half of the position is cut off. The length of six places was measured at a distance of 3 mm from the side end surface 1b in the direction of the rotation axis on the cut surface and averaged. The lengths of the samples at the same position before the rotation test in the molten steel were also measured and averaged. The average value (μm) before the spin test in the molten steel was subtracted from the average value (μm) after the spin test in the molten steel, and the value was divided by the test time for 180 minutes to calculate the adhesion or melt loss rate (μm/min).

The adhesion or melt loss rate (μm/min) of the spin test in the molten steel was evaluated in four stages. That is, the melt loss and the adhesion amount are classified into (1) ± 10 μm/min or less, (2) ± 15 μm/min or less, (3) ± 30 μm/min or less, and (4) more than ± 30 μm/min. When the test result of the actual operation of the material having the difference in the amount of the adhesion and the amount of the adhesion is determined, it is judged that the steel type is allowed to be ±30 μm/min or less, and it is judged that the temperature is 30 μm/min or less. Here, "+" means adhesion, and "-" means melt loss.

In order to satisfy the conditions of the melting loss and the adhesion speed of ±30 μm/min or less, it is necessary to make the thickness of the slag coating layer on the surface of the sample after the rotation test in the molten steel to be 0.1 mm or more, and the sample for the generated slag coating layer. The coverage of the contact surface of the molten steel (the percentage of the contact area of the sample to the molten steel covered by the slag phase) is 50% or more, which is determined by the spin test method in the molten steel.

The thickness and coverage of the slag coating layer (which can be regarded as a molten slag phase in the molten state) generated on the surface of the sample after the test were measured as follows.

The test sample having the above-described cross section was impregnated into a resin monomer, and after polymerization, it was ground, and the slag phase formed on the surface of the refractory was microscopically measured for its thickness. In the field of contact with the molten steel in the sample 1 after the end of the test shown in FIG. 2, the wire is drawn at a pitch of 3 mm from the side surface 1b toward the rotation axis direction (refer to FIG. 2(b)), and measured in the rotation direction (refer to FIG. 2(b)). The direction of the circumferential direction, the direction of the upper surface in Fig. 2(b) and the opposite side (the opposite side of the direction in which the circumferential direction proceeds, the direction of the lower surface in Fig. 2(b)) intersects with the refractory running surface The thickness of the nearby slag coating. The details of the measurement method are as follows: the thickness of the slag layer is determined by self-healing all the boundaries (the part of the shape of the aggregate to be confirmed when the alumina aggregate is reacted with the slag) to the surface layer of the slag coating layer. The thickness thereof is taken as the average value of the respective measured values as the thickness of the slag coating layer.

The coverage rate C is measured and calculated as follows. The area in contact with the molten steel from the side end surface 1b to the direction of the rotation axis to the rotation direction side and the opposite side is 6 mm (the area from the right end to the second line in the right side in Fig. 2(b)) In the refractory running surface length (L0) (the R-shaped region from the right end to the right second line in Fig. 2(b)) and the length of the slag coating layer (L1), the following formula calculates the coverage ratio C ( %).

C(%)=L1/L0x100 Equation 1

Further, when the inventors of the present invention found that the aeration rate of the refractory is within a specific range, the continuous formation effect of the slag coating layer can be obtained more stably.

Specifically, in order to make the volatile oxidizing component stable and effective to move at a high temperature, it is preferable to have a better condition for allowing the volatile oxide to pass through, that is, to better exist as a communication in the refractory structure. The space of the path (stomata).

Therefore, the present inventors have found that the ventilation rate K at a normal temperature of a refractory material fired in a non-oxidizing atmosphere at 1000 ° C is most suitable as the index.

The ventilation rate K can be expressed by Formula 2.

K=(Q×L)/(S×(P1-P2)) Equation 2

among them

Q: the volume of air passing through the sample per unit time (cm ³ )

L: sample thickness (cm)

S: sample sectional area (cm ² )

P1: Air pressure when the sample flows in (cmH ₂ O)

P2: Air pressure when the sample flows out (cmH ₂ O)

The optimum value of the aeration rate K at room temperature of the refractory after firing in a non-oxidizing atmosphere at 1000 ° C of the present invention is in the range of 0.4 × 10 ^-3 to 4.0 × 10 ^-3 cm ² / (cmH ₂ O ‧ seconds). When the aeration rate is less than 0.4×10 ^-3 cm ² /(cmH ₂ O‧ seconds), the volatile component of the gasified slag component reaches the running surface, and the dense and viscous slag coating layer is formed continuously or for a long time. Insufficient circumstances. When the aeration rate is more than 4.0×10 ^-3 cm ² /(cmH ₂ O‧ seconds), the volatile component disappears in a short time after the start of casting, and the slag coating layer cannot be formed continuously during casting, which also leads to Al ₂ O ₃ Adhesion (under conditions of high molten steel flow rate, etc.).

Further, the aeration rate K is a value obtained by the above formula 2 by measuring the refractory having a thickness of about 30 mm to about 60 mm and a thickness of about 5 mm to about 30 mm by measuring the passing air. The sample may be cut out from the refractory in the state of the existing product, or may be prepared in advance for the measurement.

The means for obtaining the aforementioned specific aeration rate does not need to be particularly limited. This means is exemplified by the following methods, for example.

(1) When the refractory is molded, the packing density is reduced.

(2) Adjust the particle size and composition ratio of the refractory aggregate other than the volatile component (avoid the densest packing structure).

(3) A flammable liquid or a fine solid is blended in the clay for molding the refractory before forming, and a minute space is formed after the firing.

(4) Adjust the pressure during forming.

In the present invention, the Al ₂ O ₃ content in the refractory is 50% by mass or more. One part of the molten slag phase generated in the operating interface of the molten steel/refractory body reacts with the fire-resistant aggregate in the structure to determine the properties of the molten steel coating layer such as viscosity or fire resistance. The refractory aggregate which is used to stabilize and maintain the smooth, dense, viscous molten steel coating which is difficult to flow at the molten steel flow rate is preferably Al ₂ O ₃ aggregate.

Al ₂ O ₃ is a neutral oxide, which can obtain a viscous viscosity by moderate reactivity with a molten molten steel, and is excellent in corrosion resistance to molten steel, and an Al ₂ O ₃ adhesion countermeasure material is more conventional than The aggregate which is used as a main component such as ZrO ₂ or MgO has a small thermal expansion, and the refractory body which is mainly used is excellent in thermal shock resistance.

When the Al ₂ O ₃ content is less than 50% by mass, the slag coating layer formed by the reaction between the concentrated oxide and the aggregate at the operation interface is insufficient in refractoriness, so that the flow rate of the molten steel at the refractory operation interface easily flows. It is difficult to maintain a dense slag coating.

As the remaining constituents of the components of the refractory constituent elements of the present invention, an oxide other than the above may be used in combination, for example, SiO ₂ , MgO, spinel, ZrO ₂ or the like. Among them, ZrO ₂ improves the viscosity by mixing in the molten slag. Therefore, in the case where the temperature of the molten steel is higher than usual, and the flow rate of the molten steel is larger than usual, it is possible to suppress the loss of the slag coating layer and maintain the adhesion preventing effect of the Al ₂ O ₃ spacer or the like. However, under the conditions of normal molten steel temperature, molten steel flow rate, etc., when the viscosity of the slag coating layer is excessively high, adhesion of a spacer such as Al ₂ O ₃ is likely to occur. Accordingly, in general, the content of ZrO ₂ is preferably limited to 6 mass% or less of the total refractory.

Further, it may be selected from a carbide such as SiC, TiC or B ₄ C, a nitride such as Si ₃ N ₄ or BN, or a metal group such as Al, Si or Ti.

The mineral phase of Al ₂ O ₃ in the refractory composition is preferably a thermally stable corundum phase. When it is used as the Al ₂ O _{3 of} corundum, the slag phase is not dissolved at an early stage, and the function as a structure can be maintained, and the durability time of the appropriate nozzle can be maintained. Moreover, since it has the same thermal expansion characteristics as the Al ₂ O ₃ -graphite material which is a material for the main portion of the nozzle for general continuous casting, it has an advantage of being easy to handle in terms of thermal shock resistance or melt resistance.

The Al ₂ O ₃ mainly composed of the corundum preferably has an Al ₂ O ₃ purity of about 95 or more. The Al ₂ O ₃ mainly composed of the corundum has a heat-treated artificial material such as an electrofusion method or a sintering method, and a raw material which is naturally produced. When a raw material of natural origin is used as a raw material, TiO ₂ , SiO ₂ or the like is mixed as a compound or the like. The impurities in the raw material particles have little effect on the effect of the present invention.

Further, the aforementioned impurities, in particular, the smaller the particle size, and particularly the region of the invention in which the total amount of CaO and B ₂ O ₃ and R ₂ O is small, also contributes to the improvement at the interface of the Al ₂ O ₃ particles mainly composed of corundum. The adhesion of the slag phase and the like. Thus, especially in the field constituting the matrix of the particle size of about 0.21mm or less of SiO i.e. as an impurity from the main body to those of corundum Al ₂ O ₃ of SiO ₂ may be used as ₂ to play the function of the present invention One or all of the sources are used.

Moreover, in order to improve thermal shock resistance, the refractory is generally made to contain molten SiO ₂ in a coarse particle size (about 0.5 mm to about 0.1 mm). In the present invention, the molten SiO ₂ may be used in combination.

Compared with the B ₂ O ₃ or R ₂ O component, the SiO ₂ component has a low volatilization energy at a molten steel temperature level and a reducing atmosphere, and coexists with the ability to promote film formation at the molten steel/refractory interface. However, when the cerium oxide component coexists with the CaO component in the structure, it is stabilized and volatilized as a slag phase in the structure, so that the purpose of suppressing the low melting is preferably 0.21 mm or more.

The refractory of the present invention described above is disposed in part or all of the surface of the continuous casting nozzle which is connected to the molten steel, thereby preventing the adhesion of the spacer such as Al ₂ O ₃ or preventing the clogging in the nozzle. That is, in response to the individual operating conditions, Al ₂ O ₃ and the like attached to dielectric spacer state of matter, as long as the main configuration thereof can be more attached to the part. In addition, the thickness may be determined in consideration of the individual operating conditions, the degree of melt loss of the refractory of the present invention, the degree of adhesion of the spacer such as Al ₂ O ₃ , and the set time resistance.

The layer formed of the refractory of the present invention is disposed on the inner hole side of the continuous casting nozzle, and the refractory of the present invention has the same degree of thermal expansion characteristics as the Al ₂ O ₃ -graphitized layer of the main portion of the continuous casting nozzle. . According to this, the layer composed of the refractory of the present invention (especially the inner hole side layer of the nozzle for continuous casting) and the other refractory layer adjacent to the layer (especially the axis of the nozzle for continuous casting are radially oriented) The space between the layers of the Al ₂ O ₃ -graphite or the like on the outer peripheral side does not need to be a special structure for providing a layer for stress relaxation such as a collapsible mortar layer. That is, the layer formed of the refractory of the present invention and the other refractory layer adjacent thereto can be directly joined to form an integral structure.

The term "direct bonding" as used herein means that the contact layer of the refractory of the present invention and the other refractory layer adjacent to the layer do not pass through the third layer other than the refractory, such as a mortar or the like. The state of the space, such as the space. Therefore, the close state includes a case where the two layers of the structure are concavo-convexly complexed and apparently integrated, and the non-convex complex is combined and only contacts.

The specific configuration has the following types.

(1) The layer formed of the refractory of the present invention is placed in part or all of the layer on the inner side and the bottom of the nozzle for continuous casting, and the other refractory layer is placed at the axial center of the direction in which the molten steel flows downward. The type on the outer side of the radial direction and the outer side of the bottom (body).

(2) The layer formed of the refractory of the present invention is placed on part or all of the inner surface layer of the discharge hole of the continuous casting nozzle, and the other refractory layer is placed at the center of the molten steel outflow direction of the discharge hole. The axis is the type of the outer side of the radial direction of the starting point.

(3) The layer formed of the refractory of the present invention is placed on a part or all of the outer surface (including the bottom) of the molten steel impregnation portion of the continuous casting nozzle, and the other refractory layer is disposed on the inner side (nozzle) The type of the inner hole direction).

The manufacturing method of the nozzle for continuous casting of such an integrated structure can employ the same manufacturing method as the general manufacturing method of the nozzle for continuous casting. That is, the clay is formed by CIP (Cold Isostatic Press), followed by drying, firing, machining, and the like. This is based on the reason that the refractory according to the present invention contains graphite or the like which is almost the same as the graphite-containing refractory to which the above general production method is applied.

Therefore, the refractory of the present invention is disposed in part or all of the surface in contact with the molten steel to produce a nozzle for continuous casting, and a part or all of the layer formed by the refractory of the present invention in the nozzle for continuous casting, The clay to be formed therein can be filled in the mold frame simultaneously with the clay formed by the layer formed by the refractory adjacent to the layer while being pressurized by CIP forming. According to this, the structure in the vicinity of the contact portion of the two layers is concavo-convexly complexed, and there is no seam or a layer separating the two, and the like, and the structure can be integrated.

By refractory of the present invention and the configuration of the continuous casting nozzle of the refractory material, the continuous casting in a continuous casting operation with the nozzle of the surface of the molten steel contacting of preventing the adhesion of Al ₂ O _3, etc. dielectric spacers attached to or prevent the nozzle Internal blockage.

Further, to prevent Al ₂ O ₃ and the like attached via spacers to prevent clogging of the nozzle function, especially compared to Al ₂ O ₃ - graphite or zirconium and calcium as the basic constituent material of the conventional technologies and refractories for continuous casting The nozzle can be continuously maintained for a long time.

Further, the refractory of the present invention and the continuous casting nozzle in which the refractory is disposed can eliminate the occurrence of cracks caused by the high thermal expansion inherent in the CaO refractory containing the conventional technique for preventing the adhesion of the spacer such as Al ₂ O ₃ . problem. This is because the refractory of the present invention has substantially the same thermal expansion or graphite amount as the Al ₂ O ₃ -graphite refractory for the bulk and the like having excellent impact resistance, and a glass phase or a slag phase is generated in the refractory structure. The glass phase or the slag phase also has the function of alleviating stress generated inside the refractory during heating.

Further, the refractory of the present invention and the continuous casting nozzle in which the refractory is disposed can be manufactured more inexpensively and easily than the conventional refractory containing CaO. In the refractory of the present invention, the amount of graphite which is substantially the same as the thermal expansion property and the stress relaxation property of the Al ₂ O ₃ -graphite refractory which is excellent in thermal shock resistance. According to this, even if it is a structure which is in direct contact with such a refractory material excellent in thermal shock resistance, such as a main body, the mutual stress (or deformation) of the degree of destruction does not occur.

In addition, the structure of the refractory material having excellent thermal shock resistance, such as the main body portion, is integrated, and the nozzle stability during the operation is also improved as compared with the so-called divided structure.

By making such an integral structure, the nozzle can be manufactured by the same method as a normal structure. When the conventional manufacturing method is used, compared with a manufacturing method in which each component is separately manufactured in a so-called divided structure and then each component is joined by plaster or the like, it is inexpensive because of the simplification of the manufacturing steps and the advantage of the raw material cost. Made in the field. It also shortens the manufacturing steps.

Further, in the conventional refractory containing CaO, when CaO is contained in a large amount, the refractory and the nozzle are broken due to the hydration reaction (digestion) of CaO, and the like, but the refractory of the present invention can be used as a CaO source. The low form of digestibility (such as citrate or aluminate) prevents the destruction of refractories and nozzles caused by the hydration reaction of CaO. According to this, the operation and storage of the refractory of the present invention and the continuous casting nozzle in which the refractory is placed are also easy, and the countermeasure against digestion is not required.

The method for producing the refractory of the present invention will be described.

The raw material of B ₂ O 3 is preferably boric acid, and the raw material of CaO or R ₂ O is preferably a reagent having high purity such as an alkaline earth oxide or an alkali metal oxide. However, when a compound of B ₂ O ₃ , CaO or R ₂ O is also used, for example, an industrially distributed boric acid powder, a boronic acid slag, an industrial slag powder, a glass powder, a synthetic slag powder, or the like may be used. Portland cement, Al ₂ O ₃ cement, boron compound, borax powder, dolomite powder, various carbonates, and the like. Further, a citric acid base or the like which is formed of a slag-forming substrate component and a slag-forming auxiliary component may be used. However, in order to uniformly slag, it is preferred to use a slag glass fine powder which is previously adjusted and melt-pulverized.

Further, it is used to satisfy one or both of CaO, B ₂ O ₃ and R ₂ O in the refractory structure in a total amount of 1.0% by mass or more and 15.0% by mass or less, and (CaO) / (B ₂ O ₃ + R ₂ O) The adjustment of the mass ratio of 0.1 or more and 3.0 or less can be carried out by adjusting the raw materials while comparing with the results of the spin test in the molten steel.

Further, the slag-forming components can be improved in their effects by being uniformly dispersed in the refractory structure. The matrix preferably has a particle size region of about 0.21 mm or less.

In order to more uniformly disperse the slag-forming component in the matrix between the aggregates of the refractory, and to form the slag phase early, the addition of the slag-forming components is preferably added by powder, and the powder contains About 1/10 or less of the dispersed aggregate size of 90.0% by mass or more (the aggregate particle size used for the refractory for continuous casting nozzles such as a dip nozzle or a long nozzle, uniformity of structure, thermal shock resistance, and corrosion resistance) In view of the above, the maximum size is usually about 1 mm. In the present invention, particles having a size of about 0.1 mm or less may be used.

As the carbon of the aggregate particles, graphite crystals having a hexagonal mesh surface such as scaly graphite, earthy graphite particles, or artificial graphite are preferably used. In particular, the use of naturally produced scaly graphite is optimal in terms of thermal shock resistance. The carbon content in the graphite aggregate is preferably 90.0% by mass or more (excluding unavoidable impurities, including 100% by mass). When the purity is less than 90.0% by mass, the high-elasticity of the refractory structure is caused by the sintering reaction between the impurities or the impurities and other raw material particles, and the like, and the impact resistance is lowered.

These graphite-based aggregates are added as a filler between the carbonaceous bonding structures, and the strength of the structure can be improved, the thermal conductivity can be improved, and the thermal shock resistance can be improved by reducing the thermal expansion coefficient and the like. Further, by including the binder, the carbon is uniformly dispersed between the oxides and the like, and the effect of suppressing the sintering of the oxide or the low melting reaction is achieved, and the quality during the casting can be stabilized. Since it is present in such a state of being uniformly dispersed, it is preferred to use a graphite aggregate having a particle size of 2 mm or less. However, when a graphite aggregate having a particle size of less than 0.1 mm is used in the main body, the uniformity of the structure is excellent, but conversely, the thermal shock resistance is lowered. Further, when the particle size is larger than 2 mm, the thermal shock resistance is excellent, but conversely, the components in the structure are likely to be unevenly distributed. Therefore, the particle size of the graphite aggregate is preferably from 0.1 mm to 2 mm. Further, various carbon blacks may be used in the graphite as the carbon of the aggregate particles.

The Al ₂ O ₃ of the refractory of the present invention has a particle size of more than 0.2 mm, preferably 70.0% by mass or more, more preferably 90.0% by mass or more, based on the total amount of the aggregate. The reason for this is that the portion in which the slag phase is formed is preferably melted in a state in which the constituent components are uniformly dispersed in the matrix of the refractory material as much as possible, and the other particles which are the skeleton for maintaining the structure or strength of the other refractory material are melted. The slag phase or the reaction of the slag phase to form a low-melt or the like causes deterioration of the structure as small as possible. In addition, a part of the Al ₂ O ₃ aggregate can be replaced with a fire resistant property which is not easily reacted with a raw material of the slag-forming component, such as SiC, ZrO ₂ or a zirconia compound, in a range of about 10.0% by mass or less based on the entire aggregate. Aggregate. However, since the ZrO ₂ component as described above promotes the adhesion of the Al ₂ O ₃ spacer by excessively increasing the slag viscosity, it is preferably limited to 6% by mass or less in the entire refractory.

Here, the slag-forming component and the remaining portion other than carbon may contain an unavoidable component derived from a raw material or a mixture in the production other than the above-described Al ₂ O ₃ . Among these unavoidable components, impurities such as Fe ₂ O ₃ and TiO ₂ are preferably suppressed to about 1.0% by mass or less. The reason is that there is a possibility that the viscous portion of the slag phase in the semi-molten state is lowered.

These powders are mixed to form a homogeneous powder mixture. Then, a binder such as a phenol resin, a pitch, or a coke which is a carbon raw material for the bonded structure is appropriately selected and added to the powder mixture, and the molding clay is uniformly kneaded. The raw material to be the binder may be a powder or a liquid, but it is important to adjust the plasticity of the clay in accordance with the clay characteristics suitable for forming.

Next, an example of a method of producing a continuous casting nozzle in which the refractory obtained from the clay of the refractory of the present invention is disposed in the inner hole side layer will be described.

In addition to the clay of the refractory of the present invention, a clay for the outer peripheral side layer, that is, a body for a continuous casting nozzle (preferably a usual manufacturing method) is separately produced. Next, a plurality of spaces separated by a specific size for forming the inner hole side layer and the outer peripheral side layer in the molding die are provided, and each of the space in the molding die is filled with each of the specially made clays, thereby removing the space. The barrier or the like directly contacts the adjacent clay.

The CIP device is simultaneously formed by simultaneously pressing the directly contacted clay. The obtained shaped body is subjected to heat treatment at 600 ° C or more and 1300 ° C or less in an oxidizing atmosphere in a non-oxidizing atmosphere or a state in which an anti-oxidation treatment is applied to the surface. Further, before the heat treatment, an independent heat treatment step for removing volatiles or resin hardening or the like at a temperature lower than the above temperature may be included. Finally, it is processed in the same manner as the production of a nozzle for continuous continuous casting.

The basic operations of the above steps, the working method, the apparatus used, and the like can be the same as the manufacturing method of the general continuous casting nozzle.

Further, the refractory of the present invention can be disposed as one of the inner pore layer side surfaces only on the surface of the inner hole of the continuous casting nozzle as described above. However, it is not limited to the inner hole layer side, and other portions such as a bottom portion, a discharge hole, an outer surface, and the like which are in contact with the molten steel, and the body portion or the continuous casting nozzle may be used as a whole.

The method for producing a nozzle for continuous casting using the refractory of the present invention is not limited to the method for producing one of the other materials as the inner hole side layer, and the following method may be employed: (1) a tube made of a cylindrical molded body The body is attached to the inner hole of the separately manufactured body portion, fixed by stucco or the like, or (2) the nozzle body portion and the inner hole side layer portion are formed as a single body by using one of the refractory materials of the present invention. The method.

[Examples]

Next, an embodiment (including an experimental example) of the present invention is shown. Further, in the experimental examples of the examples, the formation of the slag coating layer and the adhesion of the spacer such as Al ₂ O ₃ were evaluated by the above-described molten steel rotation test method.

<Example A>

Example A is an experimental example in which the effects of CaO, B ₂ O ₃ and R ₂ O were investigated. Table 4 shows the composition of the sample to be tested, the components of each sample to be tested, and the like, and the results.

As shown in Examples 1 to 10, it is understood that the CaO component is contained in an amount of 0.5% by mass or more, and any one of B ₂ O ₃ and R ₂ O or a total amount of both of them is 0.5% by mass or more. The thickness of the slag coating layer is 0.1 mm or more, and the coverage of the slag coating layer is 50% or more. Further, in the case of the adhesion rate of the sample to be tested or the melt loss rate of the sample, any of the examples has an adhesion speed of +30 μm/min or less, and can satisfy the criterion of ±30 μm/min or less (melt loss or adhesion).

Further, Example 3, Example 4, and Example 5 are examples in which the R type of R ₂ O is changed to Na, K, and Li. All of the embodiments can satisfy the thickness of the slag coating layer, the coverage rate, and the melting loss or adhesion speed in the reference. That is, it can be understood that the R species Na, K, and Li of R ₂ O have no effect on the results of the present invention.

With respect to Comparative Examples 1 to 5 of the above examples, only the thickness of the slag coating layer exceeded 0.1 mm, and the coverage ratio and the melt loss or the adhesion speed of any of the comparative examples were not satisfied. That is, in these comparative examples, the slag coating layer for suppressing the adhesion of the spacer such as Al ₂ O ₃ could not be sufficiently formed.

<Example B>

In the example B, an experimental example in which the effect of replacing one part of the Al ₂ O ₃ aggregate of the main component of the refractory with MgO was examined based on the sample of the above-mentioned Example 6. Table 2 shows the composition of the sample to be tested, the components of each sample to be tested, and the like.

Each of the samples of Example 11, Example 12, and Example 6 in which the Al ₂ O ₃ content was 50% by mass or more satisfies the thickness of the slag coating layer, the coverage ratio, and the melt loss or adhesion rate in the reference. However, Comparative Example 6 in which the Al ₂ O ₃ content was 47.4% by mass did not satisfy the thickness of the slag coating layer, the coverage ratio, and the melt loss or adhesion rate in the reference.

<Example C>

Example C is an experimental example in which the effect of changing the carbon content was examined based on the sample of Example 6 described above. Table 3 shows the composition of the sample to be tested, the components of each sample to be tested, and the like.

Any of the samples of Example 13, Example 6, and Example 14 having a carbon content of 8.0% by mass or more can satisfy the thickness of the slag coating layer, the coating ratio, and the melt loss or adhesion rate in the reference. However, in Comparative Example 7 in which the carbon content was less than 8% by mass and was 7.3% by mass, the thickness of the slag coverage was slightly less than the standard, and the coverage and the melt loss or the adhesion rate were not satisfied. This is considered to be insufficient for reducing the atmosphere in which B ₂ O ₃ or R ₂ O is volatilized. Further, in Comparative Example 8 in which the carbon content was more than 34.5% by mass, only the slag coverage ratio thickness was satisfied, but the coverage ratio was not satisfied, and the melt loss rate was increased, and the melt loss rate standard could not be satisfied. It is considered that the viscous slag coating layer is insufficient and the surface of the refractory surface exposed to the molten steel is increased, and carbon is dissolved toward the molten steel.

In addition, the carbon content of the example 13 is 8.2% by mass, but it is estimated that the carbon content is 8.0% by mass or more when the relative content of Comparative Example 7 is slightly less than the standard. (The area of the carbon content is the same as the content of the components constituting the other slag. Therefore, it is considered that the thickness of the slag coating layer changes linearly with the carbon content as a variable. Therefore, it is estimated that the carbon content is 8.0% by mass or more. .

<Example D>

Example D is a test example in which the effect of changing the total amount of CaO, B ₂ O ₃ , and R ₂ O was investigated. Table 4 shows the composition of the sample to be tested, the components of each sample to be tested, and the like, and the results.

In the present example, it was confirmed that the total amount of CaO, B ₂ O ₃ and R ₂ O was at most 16% by mass based on the sample of Example 6. Any of the examples in which the total amount of CaO, B ₂ O ₃ , and R ₂ O is 1.0% by mass or more and at most 16% by mass can satisfy the thickness, the coating ratio, and the melt loss or adhesion rate of the slag coating layer in the reference. Further, in Comparative Example 9 in which the total amount of CaO, B ₂ O ₃ and R ₂ O was 16% by mass, the tendency of the melt loss and the thickness of the slag coating layer and the coating ratio were small, and the coating ratio was C. A portion close to D was observed. Such a tendency can adjust or control to some extent other components (such as ZrO ₂ ) other than Al ₂ O ₃ that react with the slag phase. However, from the viewpoint of stably maintaining the slag coating layer in a system mainly composed of Al ₂ O ₃ aggregates, the total amount of CaO, B ₂ O ₃ and R ₂ O is preferably 15% by mass or less. The total amount of the refractory of the present invention is set to 15% by mass or less.

Here, the properties of the slag coating layer of the present invention, the behavior of the CaO component, the volatile components of B ₂ O ₃ and R ₂ O in the refractory of the present invention, and the like are shown. Specific examples.

Fig. 5 is a cross-sectional view showing the structure from the vicinity of the running surface of the sample to the center side after the experiment in the molten steel test, (A) is a refractory of the prior art (Comparative Example 1), and (B) is the present invention. (Refertion 17) refractory. In Fig. 5(A), the circled number 1 (hereinafter, "the circled number n" is described as "circle n") is a conventional Al ₂ O ₃ -graphite refractory structure, and the circle 2 is the aforementioned The attachment layer of the running surface of circle 1. Further, in Fig. 5(B), the circle 3 is the refractory structure of the present invention, the circle 4 is the slag coating layer (the slag phase of the viscous semi-molten carbon between the heating), and the circle 5 is the space (indicating no adhesion layer). .

The slag coating layer of the circle 4 is formed in a concavo-convex shape on the contact surface with the molten steel (circle 5), and it is understood that the interface with the refractory material penetrates into the void of the pores of the refractory or the like. This shows that the slag coating layer is a slag phase in a viscous and semi-molten state between heatings. (The more the contact surface of the low viscosity and the molten steel becomes a linear smooth surface, and the higher the viscosity, the more difficult it is to penetrate the void of the refractory or the like, but the present embodiment is Kind of tendency).

Further, Fig. 6 is a view showing the composition of the inside and the running surface of the refractory material of the present invention shown in Fig. 5 (B) (the change in the composition ratio with the distance from the inside of the refractory body of the running surface). The positions of A, B, and C (blank circle marks) in Fig. 5(B) are respectively mapped to A, B, and C in Fig. 6.

D in Fig. 6 shows the composition of the sample center position of Fig. 5(B). (Because D in Fig. 6 is further below the microscope photographing range shown in Fig. 5(B), it is not shown in Fig. 5(B)).

Further, the component values of the A, B, C, and D are measured for one of the substrates. That is, the component qualities of the positions are not proportional to the total amount of the refractory, so that the absolute value is meaningless, but the relative difference between the respective positions can be confirmed.

As can be seen from Fig. 6, in addition to the slag coating layer, the amount of the CaO component is substantially the same from the running surface of the refractory to the inside, and the amount of the volatile components of B ₂ O ₃ and R ₂ O is gradually closer to the running surface of the refractory. More, especially near the running surface.

Further, the amount of the volatile components of B ₂ O ₃ and R ₂ O in the molten steel coating layer is increased more, and CaO is inversely smaller.

The relative components of the B ₂ O ₃ and R ₂ O in the slag coating layer and the running surface side are relatively increased, indicating that the components are volatilized from the refractory structure and are directed to the running surface side or the slag coating layer. mobile. And such a change in the amount of CaO indicates that CaO in the slag coating layer reacts with the molten steel component (Al ₂ O ₃ , S, etc.) and flows out into the molten steel.

<Example E>

Example E is an experimental example in which the effect of changing the value of CaO/(B ₂ O ₃ + R ₂ O) was investigated. Table 5 shows the composition of the sample to be tested, the components of each sample to be tested, and the like, and the results.

In the present embodiment, based on the sample of Example 17, the mass ratio CaO/(B ₂ O ₃ + R ₂ O) was confirmed from the range of the minimum 0.1 to the maximum 3.2. As a result, any of the examples can satisfy the thickness, the coverage, and the melt loss or adhesion speed of the slag coating layer in the reference. However, with the change in the ratio of the values of Example 23 to Comparative Example 10 in which the CaO component was large, the tendency of the melt loss and the thickness of the slag coating layer and the coverage ratio were observed to be small. Further, in Comparative Example 10, although the coverage ratio was C, a portion close to D was also observed. Since implemented in Al ₂ O ₃ as a main aggregate view of the system to maintain the slag layer covering the concept of stability, a mass ratio of _{CaO / (B 2 O 3 +} R 2 O) is preferably at most 3.0% by mass or less, it is The mass ratio before the refractory of the present invention is set to 3.0% by mass or less.

<Example F>

Example F is an experimental example in which the effect of changing the aeration rate (the value at room temperature after firing in a non-oxidizing atmosphere at 1000 ° C) was examined. Table 6 shows the composition of the sample to be tested, the components of each sample to be tested, and the like.

In the present embodiment, based on the sample to be tested in Example 6, the change in the aeration rate was changed by changing the pressure at the time of molding. The aeration rate was measured and calculated by the method described above. As a result, any of the examples can satisfy the thickness, the coverage, and the melt loss or adhesion speed of the slag coating layer in the reference. However, in Example 28, in which the aeration rate was 4.4 × 10 ^-3 cm ² /(cm H ₂ O.sec.), the thickness of the slag coating layer was lowered, and the adhesion speed was increased. In the system mainly composed of the Al ₂ O ₃ aggregate, the aeration rate K is preferably 4.0 × 10 ^-3 cm ² /(cm H ₂ O.sec) or less from the viewpoint of stably maintaining the slag layer.

<Example G>

Example H is an experimental example for investigating the effect of changing the content of the ZrO ₂ component. Table 7 shows the composition of the sample to be tested, the components of each sample to be tested, and the like, and the results.

In the present example, based on the sample of Example 17, the content of the ZrO ₂ component was changed by replacing the ZrO ₂ fine powder aggregate with the Al ₂ O ₃ aggregate. As a result, as the content of the ZrO ₂ component increases, the tendency from the melt loss tends to move toward adhesion. However, in any of the examples, the thickness, the coverage, and the melt loss or adhesion speed of the slag coating layer in the reference can be satisfied. However, in Example 31, in which the content of the ZrO ₂ component was 6.8% by mass, the adhesion tendency of Example 30 was higher than the content of the ZrO ₂ component of 6.0% by mass, and it was found that the change in the adhesion thickness was large in the change in the content (0.8% by mass). . The content of the ZrO ₂ component is preferably 6.0% by mass or less from the viewpoint of stably maintaining the slag coating layer in the system mainly composed of Al ₂ O ₃ aggregate.

<Example H>

Example H is an experimental example in which the effect of changing the content of the SiO ₂ component was investigated. Table 8 shows the composition of the sample to be tested, the components of each sample to be tested, and the like, and the results.

In the present embodiment, based on the sample of Example 32, the SiO ₂ component content was changed by replacing the SiO ₂ fine powder aggregate with the Al ₂ O ₃ aggregate. In the range of up to 15% by mass of the SiO ₂ component confirmed in the present embodiment, any of the examples can satisfy the thickness, the coverage, and the melt loss or adhesion rate of the slag coating layer in the reference. That is, it can be understood that the range of the content of the SiO ₂ component does not affect the effects of the present invention.

<Example I>

The first embodiment is a test example in which the refractory of the sample of the above-mentioned Example 17 is supplied to the actual continuous molten steel casting together with the refractory of Comparative Example 1.

The refractory of Example 17 was formed into an immersion nozzle of the configuration shown in Fig. 4. That is, the refractory of the present invention (symbol 10 of Fig. 4) is disposed entirely on the surface of the impregnated nozzle which is in contact with the molten steel. Further, the refractory (symbol 12) for the main body is the refractory of Comparative Example 1, and the refractory (symbol 10) of the present invention and the refractory (12) for the main body are produced by simultaneous molding, and have an integral structure.

The refractory of Comparative Example 1 is not the refractory field (symbol 10) of the present invention shown in Fig. 4, but was constructed as a submerged nozzle integrally formed with the body portion. That is, the refractory of Comparative Example 1 was all disposed on the surface of the molten steel except for the powder portion of the immersion nozzle.

Any of the immersion nozzles of the examples and the comparative examples may be used under other general operating conditions such as preheating. The impregnation nozzles of the examples and the comparative examples were preheated by a gas burner, and were supplied to a continuous aluminum deoxidized steel carbon steel having a carbon concentration of 0.1 to 0.4% under the conditions of a mold size of 350 × 450 mm and a casting speed of 0.5 to 0.8 m/min. Casting.

As a result, the maximum thickness of the Al ₂ O ₃ of Comparative Example of deposits such as 22mm, sticking speed was 42μm / min (512 minutes and 10 inches), using the embodiment of Example Comparative Example while the Al ₂ O _3, The maximum thickness of the attachment was 1.5 mm, and the attachment speed was 3 μm/min (using 512 minutes, 10 吋) (refer to Fig. 7). Further, the impregnation nozzle of the example did not cause damage such as cracks.

According to the present embodiment, it is understood that the continuous casting nozzle in which the refractory of the present invention is disposed can prevent adhesion of a spacer or the like such as Al ₂ O ₃ , and can solve the high expansion inherent in the refractory containing CaO as proposed in the prior art. The occurrence of cracks can be made cheaper and easier than conventional refractories containing CaO, and it can be obtained in a more stable structure than a divided structure (for example, a structure in which the inner hole body and the body are composed of individual parts). The nozzle.

Further, in the present embodiment, the refractory of the present invention is disposed entirely on the surface in contact with the molten steel except for the powder portion of the immersion nozzle, and the immersion nozzle of the structure shown in Fig. 4 is formed, but the refractory of the present invention is disposed only on the inner hole surface ( Symbol 10) can also be made into an impregnation nozzle of the configuration shown in Fig. 3.

1. . . Sample

1a. . . End face for the sample

1b. . . Side end of the test material

2. . . Holder

2a. . . Lower end of the holder

3. . . Fused steel

4. . . crucible

5. . . High frequency generator

10. . . Refractory of the invention

11. . . Inner hole of continuous casting nozzle

12. . . Al ₂ O ₃ -graphite refractory

13. . . Zirconia-graphite refractory

Circle 1: Al2O3-graphite refractory structure of the prior art

Circle 2: the attachment layer of the running surface of the aforementioned circle 1

Circle 3: refractory structure of the present invention

Circle 4: slag coating layer (slag phase in the semi-molten state of the adhesive between heating)

Circle 5: space (displays no attachment)

Figure 1 shows an explanatory diagram of the method of the rotation test in molten steel.

Fig. 2 is an image view of a cross-sectional view of the test material after the spin test in the molten steel, (a) being the case of adhesion, and (b) being the case of melt loss.

Fig. 3 is a cross-sectional view showing an example of the nozzle for continuous casting of the present invention (only the refractory of the present invention is used for the inner hole surface).

Fig. 4 is a cross-sectional view showing an example of the nozzle for continuous casting of the present invention (the refractory of the present invention is entirely used in contact with the molten steel).

5 is a cross-sectional view showing a structure in the vicinity of a running surface of a sample after the test using the spin test in the molten steel according to the refractory of the present invention, and (A) is a refractory of the prior art (comparative example of the embodiment), (B) is a refractory of the invention (Example 17 of the examples).

Fig. 6 is a view showing the composition of the inside and the running surface of the refractory of the present invention shown in Fig. 5(B) (the composition ratio changes with the distance between the running surface and the refractory inner direction).

Fig. 7 is a cross-sectional photograph of the continuous casting nozzle of the first embodiment, (A) is a continuous casting nozzle (immersion nozzle) of the prior art (the refractory of Comparative Example 1), and (B) is the present invention (Example) A nozzle for continuous casting (immersion nozzle) of 17 refractory).

10. . . Refractory of the invention

11. . . Inner hole of continuous casting nozzle

12. . . Al ₂ O ₃ -graphite refractory

13. . . Zirconia-graphite refractory

Claims (7)

A refractory characterized by containing 0.5% by mass or more of CaO components, each of which is 0.5% by mass or more, or a total amount of 0.5% by mass or more of B ₂ O ₃ and R ₂ O (R is Na, K, Li Any of: 50% by mass or more and 91% by mass or less of Al ₂ O ₃ , 8.0% by mass or more, and 34.5 % by mass or less of free carbon, and the total of CaO, B ₂ O ₃ and R ₂ O is 1.0% by mass or more 15.0% by mass or less, and the mass ratio CaO/(B ₂ O ₃ + R ₂ O) is in the range of 0.1 or more and 3.0 or less. For example, in the refractory material of claim 1, the air permeability at room temperature after firing in a non-oxidizing atmosphere at 1000 ° C is 0.4 × 10 ^-3 to 4.0 × 10 ^-3 cm ² / (cmH ₂ O ‧ sec) range. A refractory according to claim 1 or 2, wherein the ZrO ₂ content is 6% by mass or less (including zero). A nozzle for continuous casting characterized in that the refractory of any one of claims 1 to 3 is disposed on a part or all of the surface in contact with the molten steel. The continuous casting nozzle of claim 4, wherein the refractory material according to any one of claims 1 to 3 is disposed on a part or all of the surface in contact with the molten steel. It is formed in a single body structure directly joined to a layer other than the refractory material adjacent to the layer. A method for producing a nozzle for continuous casting, which is a method for producing a nozzle for continuous casting in which a refractory according to any one of claims 1 to 3 is disposed on a part or all of a surface in contact with a molten steel, which is characterized in that To include: Part or all of a layer consisting of the refractory material of any one of claims 1 to 3 in the nozzle for continuous casting, and the clay supplied thereto, and supplied to be formed adjacent to the layer The clay of the layer formed other than the refractory is adjacent to the same pressure and is a step of forming a molded body having an integral structure. A continuous casting method, which is characterized in that a continuous casting nozzle for refractory material according to any one of claims 1 to 3 is applied to a part or all of the surface in contact with the molten steel, and the Al ₂ O _{3 is} suppressed on one side. The spacer such as the spacer adheres to the inner wall of the continuous casting nozzle, and continuously casts aluminum deoxidized steel carbon steel having a carbon concentration of 0.1 to 0.4%.