JP2016148347A - Heat insulation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress significant deterioration or dissipation of a bio-soluble heat insulation material due to reaction with a refractory material in a high temperature area having about 1400°C or more, in a heat insulation structure containing a bio-soluble heat insulation material.SOLUTION: In a heat insulation structure, between a bio-soluble heat insulation material layer 5 and another refractory material structure 8, provided is a layer 6 for suppressing reaction with the bio-soluble heat insulation material and the other refractory material structure. The bio-soluble heat insulation material layer 5 is a layer in which bio-soluble fibrous objects are aggregated. A liquid phase ratio at 1400°C of a composition in which the bio-soluble heat insulation material and the reaction suppression layer are mixed is 22 mass% or less.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a heat insulating structure including a biosoluble heat insulating material, and more particularly to a heat insulating structure suitably applied to a steel continuous casting nozzle.

  In industries involving high temperature operation, the use of heat insulating materials is indispensable for many purposes such as energy saving and work environment improvement. In the past, as a heat insulating material for such purposes and applications, a sheet-like or blanket-like heat insulating material mainly composed of asbestos and inorganic fibers has been mainly used. Insulating materials with biosolubility that are less harmful to water are becoming mainstream.

For example, Patent Document 1 discloses that 75 to 80% by weight of SiO ₂ , 10 to 14% by weight of CaO, 4 to 9% by weight of MgO, 0.1 to ₂ % by weight for the purpose of achieving both biosolubility and heat insulation. % of _ZrO 2, comprising 0.5 to 1.5 wt% _Al 2 _{O 3,} and 0.1 to 1.5 wt% _B 2 _{O 3,} a ceramic biosoluble for high temperature insulation material Fiber has been proposed.

Thus, the biosoluble heat insulating material contains a large amount of a vitrification modifier such as an alkali metal oxide or an alkaline earth metal oxide for the purpose of enhancing the biosolubility of the fibrous heat insulating material. ₂ and B ₂ O ₃ -based glass compositions are mainly used. In recent years, glass fibers having a high alkali metal oxide content are said to be highly biosoluble and have the highest biosafety. However, since the fiber having such a composition has a low melting point and its application is limited, development of a biosoluble heat insulating material that can withstand a high temperature of, for example, 1400 ° C. or more has been promoted.

  For example, Patent Document 2 discloses that when using a heat insulating material containing only a biosoluble fiber at a temperature of 1400 ° C. or higher, a part of the fiber is melted and significantly contracted to prevent the heat resistance from being lost. A heat insulating material including fibers and alumina fibers, or a heat insulating material including inorganic particles such as zirconia powder, chromia powder, and alumina powder in addition to these fibers has been proposed.

Patent Document 3 discloses a heating device including a heating element and a heating element including a biologically soluble inorganic fiber, and a heating device including a support in which reaction between the fiber and the heating element at a high temperature is suppressed. And a support including a biosoluble inorganic fiber to be held, wherein the biosoluble inorganic fiber is not in direct contact with the heating element, or the contact between the biosoluble inorganic fiber and the heating element is reduced. Has been proposed. Further, in the same document, as the biosoluble inorganic fiber, 50 to 82% by weight of SiO _{2 and 10} to 43% by weight of the total of CaO and MgO, or SiO ₂ , ZrO ₂ , Al ₂ O ₃ and TiO _{2 are used.} Bio-soluble inorganic fibers are proposed in which the total of the total of 50 to 82% by weight and the total of the alkali metal oxide and the alkaline earth metal oxide is 18 to 50% by weight.

  By the way, in the continuous casting operation of steel, when moving the molten steel from the ladle to the tundish and from the tundish to the mold, etc., a nozzle and a protective tube (hereinafter referred to as the nozzle for continuous casting and the protection) Tubes are collectively referred to as “nozzles”). And a heat insulating material is installed in the outer periphery of these nozzles.

  The nozzle or the like is preheated to a temperature of about 900 ° C. to about 1450 ° C. immediately before being used for casting in order to prevent breakage due to thermal shock at the initial casting. However, since it is exposed to the atmosphere in a state where heating is stopped before casting after casting, the temperature drops. Also, for example, when the casting of molten steel for one cup of molten steel container such as a tundish or ladle is finished and the molten steel in the next new molten steel container is continuously cast, the molten steel passes through the nozzle or the like. A temperature drop of the nozzle or the like occurs during the switching or not. Therefore, the first purpose of installing a heat insulating material on the outer periphery of the nozzle or the like is to suppress the temperature drop of the nozzle after preheating or between castings.

  Furthermore, when the molten steel passes through the nozzle or the like, the steel is cooled by heat loss from the outer periphery of the nozzle or the like, and inclusions such as alumina in the molten steel or steel (metal ingot) that is about to harden due to cooling is the nozzle or the like. It may adhere to the inner wall and hinder the proper flow of molten steel, or may cause clogging in the nozzle or the like. Therefore, the second purpose of installing the heat insulating material on the outer periphery of the nozzle or the like is to reduce the heat loss of the molten steel during casting.

  The temperature of the molten steel is as high as about 1500 ° C., and the nozzles are exposed to such a high temperature for a long time and directly or indirectly. In addition to its high thermal insulation performance, its sustainability is also important.

  On the other hand, since nozzles used for continuous casting of steel mostly contain a large amount of carbon, in order to form a layer having a gas isolating function on the surface in contact with the outside air, that is, the outer periphery of the nozzle, etc. A layer of an antioxidant containing a large amount of the glass composition (hereinafter, the antioxidant containing a large amount of the glass composition is also simply referred to as “antioxidant”) is provided.

  The glass composition as described above, in particular, a biosoluble heat insulating material containing a large amount of alkali metal oxides or alkaline earth metal oxides, and an antioxidant layer containing a large amount of glass composition or a main component on the outer peripheral surface. When installed on the outer periphery of a nozzle or the like provided, both of them are further melted due to a synergistic effect, and the fibrous biosoluble heat insulating material melts from the side close to the nozzle and the like so that the fiber structure and its layer structure cannot be maintained. The layer itself will disappear.

Special table 2013-520580 gazette JP 2013-71848 A JP 2013-243071 A

  The present invention relates to a heat insulating structure including a biosoluble heat insulating material mainly composed of fibers containing a large amount of alkali metal oxide and having high biosolubility, which is installed in contact with a refractory, and has a high temperature of about 1400 ° C. or higher. Suppresses the significant alteration (hereinafter collectively referred to as alteration including shape, form, etc., such as melting, aggregation, shrinkage, etc.) or disappearance due to the reaction with the refractory in the region. The purpose is to do.

  The present invention also relates to a biosoluble heat insulating material used in contact with the antioxidant material layer, such as a nozzle for continuous casting having a surface of an antioxidant material rich in glass composition on the surface. Another object is to suppress significant alteration or disappearance in a high temperature range.

  This invention provides the heat insulation structure as described in the following 1-13.

1. The heat insulation structure provided with the reaction suppression layer with the said biosoluble heat insulating material and the said refractory structure between the layer of biosoluble heat insulating material, and the refractory structure.

2. The layer of the biosoluble heat insulating material is a layer in which biosoluble fibrous materials are gathered, and a liquid phase at 1400 ° C. of a composition obtained by mixing the biosoluble heat insulating material and the reaction suppressing layer. 2. The heat insulating structure according to 1, wherein the rate is 22% by mass or less.

3. 3. Said reaction suppression layer contains 94 mass% or more of ZrO ₂ and SiO ₂ in total as chemical components after heat treatment in an oxidizing atmosphere at 1000 ° C., and the balance is composed of refractory components other than the above. Thermal insulation structure.

4). The heat insulation structure according to 3, wherein the content of ZrO ₂ in the reaction suppression layer is 60% by mass or more.

5. The heat insulation structure according to 3 or 4, wherein a part or all of ZrO ₂ and SiO ₂ in the reaction suppression layer constitutes zircon.

6). The heat insulation structure according to any one of 1 to 5, wherein an average particle diameter of the constituent particles in the reaction suppression layer is 0.5 mm or less.

7). The biosoluble heat insulating material contains a total of 90% by mass or more of SiO ₂ , Al ₂ O ₃ and K ₂ O as chemical components after heat treatment in an oxidizing atmosphere at 1000 ° C., and the balance is a metal oxide other than the above, The heat insulating structure according to any one of 1 to 6, comprising at least one component selected from borides.

8). The heat insulating structure according to 7, wherein the content of K ₂ O in the biosoluble heat insulating material is 20% by mass or more and 30% by mass or less.

9. 9. The heat insulation structure according to any one of 1 to 8, wherein the refractory structure is made of a carbon-containing refractory.

10. A layer of an antioxidant that blocks part of or all of the surface of the refractory structure that is in contact with the reaction-suppressing layer and that is partially or wholly melted at 1000 ° C. or less and blocks the passage of air. , 9 insulation structure.

11. 11. The heat insulating structure according to 10, wherein when the reaction suppression layer is added to the antioxidant layer, the liquid phase ratio decreases as the amount added increases.

12 The said refractory structure is a heat insulation structure of 10 or 11 which is a nozzle for continuous casting of steel.

13. The layer of the antioxidant is disposed on a part or all of the surface of the nozzle for continuous casting of the steel that is in contact with the atmosphere or the oxidizing gas, and the reaction suppression layer is formed on the outer surface of the layer of the antioxidant. Is further installed on the outer surface thereof, the thickness of the antioxidant layer is 0.3 mm or more and 1.0 mm or less, and the thickness of the reaction suppression layer is The heat insulating structure according to claim 12, wherein the thickness of the layer of the biosoluble heat insulating material is not less than 0.6 mm and not more than 1.5 mm, and not less than 3 mm.

  Since the heat insulation structure of the present invention includes a reaction-inhibiting layer between the biosoluble heat insulating material and the refractory structure between the biosoluble heat insulating material layer and the refractory structure, the heat insulating structure is about 1400 ° C. or higher. It is possible to suppress significant deterioration or disappearance of the biosoluble heat insulating material due to the reaction with the refractory structure in the high temperature range.

  In addition, according to the present invention, even if the refractory structure has a composition with a high liquid phase ratio, a biosoluble heat insulating material can be applied, and naturally various compositions having a liquid phase ratio equal to or lower than that can be applied. A biosoluble heat insulating material can also be applied to the refractory structure.

It is a graph which shows the relationship by calculation of temperature and a liquid phase rate in an example of the biosoluble heat insulating material applicable to this invention, and an example of the conventional heat insulating material (non-biosoluble heat insulating material). It is a graph which shows the relationship between the ratio of the reaction suppression layer of this invention with respect to the biosoluble heat insulating material applicable to this invention, and the liquid phase rate in 1400 degreeC. It is a graph which shows the relationship between the ratio of the reaction suppression layer of this invention with respect to the antioxidant applicable to this invention, and the liquid phase rate in 1400 degreeC. It is an external appearance photograph which shows the state of the comparative example 1 and Example 1 (left-right extending) after heating to 1500 degreeC in Example A. It is a structure | tissue photograph by a microscope which shows the boundary part of the biosoluble heat insulating material layer, the reaction suppression layer, antioxidant layer, and the nozzle body for continuous casting after heating to 1400 degreeC of Example 1 in Example A. It is the structure | tissue photograph by a microscope which shows the boundary part of the biosoluble heat insulating material layer, antioxidant material layer, and nozzle body for continuous casting after heating to 1400 degreeC of the comparative example 1 in Example A.

  The present invention is described in detail below.

  Biosoluble heat insulating material, which is an aggregate of fibers with a high level of biosolubility by containing a large amount of alkali metal oxide, melts, aggregates, shrinks, etc. due to reaction with refractories that come into contact with it at high temperatures. May cause loss of the fibrous form, a significant change in the shape and structure of the heat insulating layer or the loss of the layer itself, and the heat insulating function may be lost. This reactivity varies depending on the chemical composition of the refractory that comes into contact with the biosoluble heat insulating material, the mineral composition, the structure of the constituent particles, and the like.

In addition, even if a biosoluble heat insulating material is a type | system | group containing many alkali metal oxides, it will be equipped with required heat resistance performance according to a use independently. For example, a typical biosoluble fiber for high temperature has a chemical composition of about 35% by mass of Al ₂ O ₃ , about 32% by mass of SiO ₂ , about 25% by mass of K ₂ O and about 7% by mass of ZrO _2. In the case where it is used alone at least without contact with other refractories, or when used under the condition of being in contact with refractories having a very low reactivity with this, it is a long time at a high temperature up to about 1450 ° C. The melt begins to melt at 1500 ° C.

However, biosoluble heat insulating materials having such a composition are Al ₂ O ₃ —SiO ₂ type, Al ₂ O ₃ —SiO ₂ —RO (where R is an alkaline earth metal) type, Al ₂ O ₃ —SiO. _When contacted with a material such as a _2- R ₂ O (where R is an alkali metal) system or a system containing an oxide that promotes low melting of these, the biosoluble heat insulating material is an aggregate of fibrous materials. In addition, the reactivity may be high, and the liquid phase ratio increases and moves into the refractory, so that it is likely to be noticeably altered or lost.

  Therefore, in the present invention, between the biosoluble heat insulating material and the refractory that tends to cause low melting as described above, the liquid phase ratio of the biosoluble heat insulating material is not increased, and low melting is easily caused. A refractory layer (hereinafter also simply referred to as “reaction suppression layer”) that does not cause low melting or disappearance of the refractory was decided to be installed.

  When the present inventors investigated the liquid phase rate in 1450 degreeC in which a biosoluble heat insulation material shows stable durability independently, it turned out that it is about 22 mass%. The influence of this liquid phase ratio on the behavior of the biosoluble heat insulating material made of fibers is considered to be dominant in terms of mechanical structure if the liquid phase ratio is the same. Therefore, the reaction suppression layer of the present invention preferably has a composition capable of maintaining the liquid phase ratio at a target temperature of 1400 ° C. at about 22% by mass or less even by contact with a biosoluble heat insulating material. In other words, in this invention, it is preferable that the liquid phase rate in 1400 degreeC of the composition which mixed the layer of the biosoluble heat insulating material and the reaction suppression layer is 22 mass% or less.

The chemical composition of a typical biosoluble heat insulating material is as follows: a total of 90% by mass or more of SiO ₂ , Al ₂ O ₃ and K ₂ O as chemical components after heat treatment in an oxidizing atmosphere at 1000 ° C. And one or more components selected from borides. K ₂ O in the biosoluble heat insulating material is generally 20% by mass or more and 30% by mass or less. If it is a biosoluble heat insulating material having a liquid phase ratio of about 22% by mass at 1450 ° C., its components are naturally limited. If it is a composition, the liquid phase rate in 1400 degreeC can be made into about 22 mass% or less.

  The liquid phase ratio is specified by calculation based on the assumption of uniform components and steady state by the software “FACTSAGE” manufactured by Thermo Fact / CRCT, GTT Technologies.

  In the present invention, the reaction suppression layer is provided as a reaction suppression layer. Thereby, even when the refractory side on which the layer of the biosoluble heat insulating material is installed is highly reactive with the biosoluble heat insulating material, the composition is hardly affected by the composition, etc. The heat insulating function can be maintained without causing alteration or disappearance of the layer of the soluble heat insulating material.

The refractory constituting the reaction suppression layer preferably contains 94% by mass or more of ZrO ₂ and SiO ₂ as chemical components after heat treatment in an oxidizing atmosphere at 1000 ° C. The balance may contain refractory components other than those mentioned above, specifically, one or more refractory components selected from metal oxides, carbides, borides, and metals.

The ZrO ₂ content in the reaction suppression layer is more preferably 60% by mass or more. This is because when the ZrO ₂ content is 60% by mass or more, the decrease in the liquid phase ratio and the increase in the viscosity of the liquid phase tend to become more stable. This ZrO ₂ may be any one of one or more zirconia or zircon mineral composition of stabilized, unstabilized or partially stabilized, and a plurality of them may coexist. When the ZrO ₂ component is 60% by mass or more, the viscosity of the liquid phase generated by the reaction with the biosoluble heat insulating material is increased, and the increase in the liquid phase and the deformation or disappearance of the biosoluble heat insulating material are suppressed. The effect becomes even more pronounced. In addition, HfO ₂ that is difficult to separate may be included in the content of ZrO ₂ .

Some or all of the of SiO ₂ may be derived from a mineral consisting of SiO ₂ zircon or crystalline or amorphous.

  The average particle diameter of each constituent particle in the reaction suppression layer is preferably 0.5 mm or less. The smaller the particle size, the higher the liquid phase generation rate due to the reaction with the biosoluble heat insulating material, but the higher the viscosity is. When the viscosity of the liquid phase is increased early, a certain region (same as the length in the thickness direction) of the contact portion with the reaction suppressing layer of the biosoluble heat insulating material moves to the reaction suppressing layer side by reaction. After that, the movement stops and the moving area (a certain area portion) becomes a gap. By such void formation, the subsequent reaction between the biosoluble heat insulating material and the reaction suppressing layer can be stopped, and the layer of the biosoluble heat insulating material can be maintained. This phenomenon contributes to the stable maintenance of the layer of biosoluble insulation material for a long time, particularly at high temperatures.

The reaction suppression layer can be placed in contact with a surface of a refractory structure to be protected, that is, a structure made of various refractories. Here, the “refractory structure” means, for example, Al ₂ O ₃ —SiO ₂ type, MgO type, Al ₂ O ₃ —MgO type, ZrO ₂ type, alumina cement component, carbon, carbide, nitride, Structures made of refractories that are generally widely used, including borides and the like.

  Particularly in the case of a refractory structure made of a refractory containing a component that oxidizes during preheating or use, such as a carbon-containing refractory, an anti-oxidant is often applied to the surface thereof. The antioxidant layer and the reaction suppression layer are in direct contact. Part or all of the layer of the antioxidant melts at, for example, 1000 ° C. or less to block the passage of air. The temperature at which a part or all of the composition melts can be arbitrarily set depending on the application. Such an antioxidant layer may contain, for example, an oxide or a non-oxide which is difficult to be in a molten state or has a slow melting rate, for the purpose of maintaining or strengthening its structure / function. . Even in such a case, as long as some or all of the composition melts and blocks the passage of air, the antioxidant function can be achieved regardless of the liquid phase ratio calculated on the assumption that the entire layer is homogeneous. And the hot properties of the molten part are similar. In other words, oxides or non-oxides that are mixed in the antioxidant material layer, difficult to be in a molten state, or have a slow melting rate, etc. Since it hardly participates in the liquid phase generation in the layer, the liquid phase rate of the portion that is distributed at least throughout the layer and blocks the passage of air is the portion excluding the above-mentioned components that are not involved in the liquid phase generation, that is, the living body The liquid phase ratio of the antioxidant layer when the reaction due to contact with the soluble insulating layer occurs can be regarded as almost 100%.

  In the prior art in which a thin fiber shape is in direct contact with the antioxidant layer, the biosoluble heat insulating material is in a very short time in the melted portion in the antioxidant layer. In addition, the present inventors have confirmed through experiments that the entire layer melts and disappears, and that the tendency becomes remarkable at 1400 ° C., which is the object of the present invention. This is because the change in the liquid phase ratio of the antioxidant layer when the biosoluble insulation material comes into contact with the antioxidant layer is small, and the biosoluble insulation material maintains the layer structure as described above. This is considered to be due to the high liquid phase rate that does not reach far below the liquid phase rate of 22% or less as a condition.

  By installing a reaction suppression layer between the antioxidant layer and the biosoluble heat insulating material layer, it is possible to prevent the biosoluble heat insulating material from melting and disappearing. In particular, if the liquid phase ratio at 1400 ° C. of the composition produced by contact between the biosoluble heat insulating material layer and the reaction suppressing layer is 22% by mass or less, the layer structure of the biosoluble heat insulating material is reliably maintained. (See FIG. 2).

  Even for such an antioxidant, the reaction suppression layer of the present invention decreases the liquid phase ratio as the mixing ratio increases (see FIG. 3), so that the reaction suppression layer may continue to melt. And disappearance of the layer structure can be suppressed.

  In addition, industrially, as a "refractory structure" with which a heat insulating layer (including a reaction suppression layer) is in direct contact, this antioxidant is considered to have the lowest melting point and high liquid phase rate. The disappearance is considered to be the most severe condition. Therefore, for a refractory structure made of a material that is less liable to form a liquid phase with the reaction suppression layer than with such an antioxidant layer, it is natural that the reaction suppression layer and the biosoluble heat insulating material layer be melted. Loss is less likely to occur.

  A typical example of a “refractory structure” having an antioxidant layer on its surface is a steel continuous casting nozzle containing about several to 30% by mass of carbon. In the case of the nozzle for continuous casting of steel, the thickness of the antioxidant layer is from 0.3 mm to 1.0 mm, the thickness of the reaction suppression layer is from 0.6 mm to 1.5 mm, The thickness of the biosoluble heat insulating material layer is generally about 3 mm to about 12 mm. That is, the thickness of the reaction suppression layer may be equal to or greater than the sum of the reaction allowance with the antioxidant material layer and the reaction allowance with the biosoluble heat insulating material layer. However, depending on the shape, structure, usage conditions, etc., if the thickness of the reaction suppression layer is too thick, it may cause partial or complete destruction or peeling, so it is necessary to optimize it according to individual conditions. .

[Calculation Example A]
The liquid phase rates of the biosoluble heat insulating material and the conventional heat insulating material (non-biosoluble heat insulating material, Al ₂ O ₃ —SiO ₂ system) are shown in FIG. As described above, the liquid phase ratio is based on the calculation when assuming the uniform component and the steady state by the software “FACTSAGE” manufactured by Thermo Fact / CRCT, GTT Technologies (the same applies hereinafter).

  Table 1 shows the chemical composition of each material used in this calculation example A, and further in the following calculation example B, example A, and example B.

[Calculation Example B]
FIG. 2 shows the relationship between the ratio of the biosoluble heat insulating material to the reaction suppression layer at 1400 ° C. and the liquid phase ratio.

From FIG. 2, when the biosoluble heat insulating material comes into contact with the reaction suppression layer and moves to the reaction suppression layer, the reaction suppression of the biosoluble heat insulating material when the liquid phase ratio of the mixture becomes 22% by mass. It turns out that the ratio with respect to a layer is 0.38 (mass ratio). Converting this to a thickness, density of the reaction inhibiting layer = 3.6 g / cm ^3, from a density = 0.128 g / cm ³ biosoluble insulation inhibition layer to the thickness 1 of the biosoluble insulation material Is 0.094, and in this calculation, the thickness of the reaction suppression layer may be 0.094 times or more that of the biosoluble heat insulating material.

[Calculation Example C]
FIG. 3 shows the relationship between the ratio of the reaction suppression layer to the antioxidant layer at 1400 ° C. and the liquid phase ratio.

  From FIG. 3, it can be seen that when the reaction suppression layer component is added to the antioxidant layer, the liquid phase ratio of the antioxidant layer decreases as the amount thereof increases. From this, it can be seen that the antioxidant layer is not further melted down and lost.

[Example A]
In Example A, when a biosoluble heat insulating material is installed in a continuous casting nozzle (immersion nozzle) of steel having an antioxidant layer on the outer periphery of the main body, the comparison was made by the presence or absence of the reaction suppression layer of the present invention. The test results are shown.

The continuous casting nozzle (immersion nozzle) used in this example is partly ZrO ₂ —C quality near the center in the longitudinal direction, and other parts are Al ₂ O ₃ —SiO ₂ —C quality, and the outer diameter is 150 mm. ˜160 mm, a liquid phase is produced on the outer peripheral surface to an extent of blocking oxygen at 1000 ° C. or less, and the liquid phase is maintained even at 1400 ° C. (however, it does not dissolve in the liquid phase or is used for its operation) Under the conditions, the dissolution rate is extremely low, including structures that remain in the liquid phase.) With a general structure in which the layer of antioxidant in the state is evenly installed with a thickness of 0.6 mm It is.

  The outer periphery of the continuous casting nozzle provided with this antioxidant layer is divided into two in the longitudinal direction. One of them is (1) a biosoluble heat insulating material (Table 1) 12 so as to be in direct contact with the antioxidant layer. .5 mm thickness (Comparative Example 1), (2) The reaction suppression layer of the present invention is 1 mm thick between the antioxidant layer and the biosoluble heat insulating material (12.5 mm thickness). (Example 1).

  In the heating test, the inner hole temperature was heated from the inner hole of the continuous casting nozzle with a burner at each temperature of 1300 ° C., 1400 ° C., and 1500 ° C., kept for 30 minutes, and then cooled to observe the state.

  In this example, even when a non-biosoluble heat insulating material was installed in the continuous casting nozzle provided with the antioxidant layer (Comparative Example 2), the same heating was performed for each heating test. A comparison was made.

  Table 2 shows the results, and FIG. 4 shows an appearance photograph of the sample after heating at 1500 ° C. in Example 1 and Comparative Example 1. In this example, the state of the sample after heating at 1400 ° C. also had the same tendency as the state of the sample after heating at 1500 ° C. However, since the difference after heating at 1500 ° C. can be clearly seen, FIG. A sample after heating at 1500 ° C. is shown.

  Here, in Table 2, ◎ is the best when the original shape is almost maintained, ○ is good in the remaining state close to the original shape even though there are deformations and thinning parts, and △ is the deformation and thinning as a whole The state where the change is considered to be progressed with use for a long time and the change is likely to progress, x indicates a defect in a state where the original shape is not substantially retained.

  At 1300 ° C., all examples maintain the original shape and there is no difference.

  At 1400 ° C., Example 1 and Comparative Example 2 maintain the original shape, and there is almost no difference between these examples. However, in Comparative Example 1 in which the biosoluble heat insulating material layer was placed in direct contact with the antioxidant layer, the biosoluble heat insulating material layer was reduced to a thickness of about several mm to 6 mm at 1400 ° C and 1500 ° C. The original form was not kept and the result was bad.

  At 1500 ° C., in Example 1, although the biosoluble heat insulating material itself was somewhat deformed and decreased in thickness, the biosoluble heat insulating material layer remained with a thickness of about 8 to 10 mm. .

  Regarding Example 1, as can be seen from FIG. 2, there is a portion where the liquid phase ratio exceeds 22% within a certain range of the ratio of the biosoluble heat insulating material to the reaction suppression layer. However, when dissolution progresses (the proportion of the biosoluble heat insulating material increases due to dissolution) and the liquid phase rate reaches 22% or less beyond that range, the biosoluble heat insulating material dissolves (disappears) there. Is thought to stop.

  Further, in Example 1, a space of about several mm was distributed between the biosoluble heat insulating material and the reaction suppression layer (there is also a distribution of the cross-linked portion) (see FIG. 4). The existence of this space is considered to be because the biosoluble heat insulating material moved while melting in the reaction suppression layer in the initial stage, but stopped after a certain amount of movement. This is also considered that the biosoluble heat insulating material layer contributes to the persistence due to its own heat resistance after a certain period of time.

  On the other hand, the sample after heating at 1400 ° C. in Comparative Example 1 has no space between the biosoluble heat insulating material and the antioxidant material layer, and the biosoluble heat insulating material continuously moves to the antioxidant material layer side. You can see that

  In Comparative Example 2, it is considered that the heat insulation material itself is somewhat deformed and reduced in thickness at 1500 ° C., and the change is expected to progress with use over a long period of time. Smaller than insulation.

  Microstructure photographs of the material boundary portions of the samples after heating at 1400 ° C. are shown in FIG. 5 for Example 1 and FIG. 6 for Comparative Example 1.

  In Example 1, the biologically soluble heat insulating material and the antioxidant material layer and the reaction suppression layer placed between them are in close contact with each other, but each is clearly separated at each interface, It can be seen that the reaction suppressing layer suppresses the reaction between the biosoluble heat insulating material and the antioxidant layer. In addition, each of them is in an independent state, and mutual dissolution or formation of a liquid phase or reduction in viscosity of all the mixtures is not recognized.

  In contrast to Example 1, it can be seen that in Comparative Example 1, integration into the biosoluble heat insulating material layer and the oxidation layer proceeds.

[Example B]
Example B is an example in which Example 1 and Comparative Example 2 of Example A were used as separate continuous casting immersion nozzles, and were used for actual continuous casting of steel. Comparative Example 1 was excluded from the sample because it could not withstand preheating at 1400 ° C. from the results of Example A.

  The preheating temperature is 1400 ° C., the molten steel temperature is about 1500 ° C., and the casting time is about 400 minutes.

  None of the samples caused significant deformation or loss of the insulation during preheating. There was no breakage due to thermal shock after preheating or at the start of casting.

The state after the end of casting is as follows.
In Example 1, although a slight deformation and thinning occurred, the heat insulating layer was almost maintained. In addition, a space was generated between the biosoluble heat insulating material layer and the immersion nozzle body (including the antioxidant layer). In addition, the antioxidant material layer (after vitrification) on the surface of the immersion nozzle body remained in a healthy state on almost the entire surface, and no alteration or damage due to oxidation of the immersion nozzle body was observed.

  In Comparative Example 2, the heat insulating layer is substantially maintained as in Example 1, and the antioxidant layer (after vitrification) on the surface of the immersion nozzle body remains in a healthy state on almost the entire surface. No deterioration or damage due to oxidation of the body was observed. In Comparative Example 2, the space between the heat insulating material layer and the immersion nozzle body (including the antioxidant material layer) was smaller than that in Example 1 or was not generated.

  From these results, the heat insulating structure in which the reaction suppressing layer is installed between the biosoluble heat insulating material and the refractory structure is a condition in which the layer of the antioxidant having a very high liquid phase ratio is interposed on the refractory structure side. However, it can be seen that it can be used under heating at 1400 ° C. and under conditions where the refractory structure side is close to 1500 ° C. Therefore, the “refractory structure” having a liquid phase ratio not as high as that of the antioxidant is naturally between the biosoluble heat insulating material layer of the present invention and the refractory structure even at 1400 ° C. It turns out that it can be set as the heat insulation structure which installed the reaction suppression layer.

DESCRIPTION OF SYMBOLS 1 Nozzle body for continuous casting 2 The biosoluble heat insulating material layer of Example 1 3 The space between the biosoluble heat insulating layer of Example 1 and a reaction suppression layer 4 The biosoluble heat insulating material layer of Comparative Example 1 5 Biolytic Modified layer of heat insulating material 6 Reaction suppression layer 7 Antioxidant layer 8 Nozzle body for continuous casting

Claims (13)

  The heat insulation structure provided with the reaction suppression layer with the said biosoluble heat insulating material and the said refractory structure between the layer of biosoluble heat insulating material, and the refractory structure.   The layer of the biosoluble heat insulating material is a layer in which biosoluble fibrous materials are gathered, and a liquid phase at 1400 ° C. of a composition obtained by mixing the biosoluble heat insulating material and the reaction suppressing layer. The heat insulation structure of Claim 1 whose rate is 22 mass% or less. The reaction suppression layer of said, the ZrO ₂ and SiO ₂ contained a total of more than 94 wt% as chemical components after heat treatment in 1000 ° C. oxidizing atmosphere, the balance being refractory component other than the claim 1 or claim 2. The heat insulating structure according to 2. The heat insulation structure according to claim 3, wherein the content of ZrO ₂ in the reaction suppression layer is 60 mass% or more. The heat insulation structure of Claim 3 or Claim 4 in which a part or all of ZrO ₂ and SiO ₂ in the reaction suppression layer constitutes zircon.   The heat insulation structure in any one of Claims 1-5 whose average particle diameter of the constituent particle in the said reaction suppression layer is 0.5 mm or less. The biosoluble heat insulating material contains a total of 90% by mass or more of SiO ₂ , Al ₂ O ₃ and K ₂ O as chemical components after heat treatment in an oxidizing atmosphere at 1000 ° C., and the balance is a metal oxide other than the above, The heat insulating structure according to any one of claims 1 to 6, comprising at least one component selected from borides. The heat insulating structure according to claim 7, wherein the content of K ₂ O in the biosoluble heat insulating material is 20% by mass or more and 30% by mass or less.   The heat insulation structure according to any one of claims 1 to 8, wherein the refractory structure is made of a carbon-containing refractory.   A layer of an antioxidant that blocks part of or all of the surface of the refractory structure that is in contact with the reaction-suppressing layer and that is partially or wholly melted at 1000 ° C. or less and blocks the passage of air. The heat insulating structure according to claim 9.   The heat insulating structure according to claim 10, wherein when the reaction suppression layer is added to the antioxidant layer, the liquid phase ratio decreases as the amount added increases.   The said refractory structure is a heat insulation structure of Claim 10 or Claim 11 which is a nozzle for continuous casting of steel.   The layer of the antioxidant is disposed on a part or all of the surface of the nozzle for continuous casting of the steel that is in contact with the atmosphere or the oxidizing gas, and the reaction suppression layer is formed on the outer surface of the layer of the antioxidant. Is further installed on the outer surface thereof, the thickness of the antioxidant layer is 0.3 mm or more and 1.0 mm or less, and the thickness of the reaction suppression layer is The heat insulating structure according to claim 12, wherein the thickness of the layer of the biosoluble heat insulating material is not less than 0.6 mm and not more than 1.5 mm, and not less than 3 mm.