JP2023130030A - Graphite-containing refractory, and iron-making vessel having the graphite-containing refractory - Google Patents

Abstract

To provide a graphite-containing refractory which can obtain high durability even if it is used under a condition that temperature rise and temperature fall are repeated over a long period, like a lining refractory such as a converter and a molten iron preliminary treatment vessel, and can obtain high durability even if it is used under a condition that an internal temperature gradient is extremely large, like a tuyere brick of a converter.SOLUTION: Carbon fiber fabrics B formed by knitting carbon fiber bundles b are knitted are embedded inside a refractory body A, the carbon fiber fabrics B contain an adhesive component c in the carbon fiber bundles b, an interval of the neighboring carbon fiber bundles b in the same direction which are adhered to or in closely contact with the refractory body A through the adhesive component c and constitute the carbon fiber fabrics B is larger than a maximum particle diameter of an aggregate constituting the refractory body A, and in a refractory cross section in a plane direction of the carbon fiber fabrics B, an area ratio occupied by the carbon fiber fabrics B to the refractory cross-sectional area is 20% or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a graphite-containing refractory in which a carbon fiber fabric woven with carbon fiber bundles is placed inside a refractory body, and a steelmaking container (converter, hot metal pretreatment container, ladle container, etc.) constructed with this graphite-containing refractory. ).

Equipment used in ironmaking and steelmaking processes at steel plants (steelmaking containers such as refining containers and transport containers) are lined with refractories so that they can withstand long-term use at high temperatures. Generally, magnesia/carbon refractories are used for the lining of converters used in the refining process, and alumina/silicon carbide/carbon refractories are used for the lining of torpedoes and blast furnace pots used in the hot metal pretreatment process. used.
The refractories used as linings in these refining vessels and transport vessels are subject to mechanical shock from the charges, abrasion from agitation of molten steel and molten slag, slag erosion from molten slag, and rapid temperature changes during operation. Used under extremely harsh conditions. Therefore, in order to perform stable operations, it is necessary to use highly durable refractories that can withstand such harsh conditions.

In particular, the tuyere bricks that make up the tuyeres of a converter have room-temperature gas (oxygen, cooling hydrocarbon gas, etc.) flowing inside them, and the inner surface of the parts near the furnace are cooled by the room-temperature gas. Since the outer surface is exposed to high temperatures due to heat transfer from the molten steel in the furnace, the thermal gradient inside the tuyere bricks is extremely large, and moreover, the molten steel must be discharged every time one charge of blowing is completed in the converter. This causes the temperature to drop, causing repeated large thermal fluctuations. The tuyere bricks installed in the converter are used frequently for about 2,500 to 4,000 charges, and are subject to extremely harsh conditions in which the large thermal gradient and large thermal fluctuations described above are repeated for each charge. Because it is used under such conditions, it must have high durability to withstand use under such conditions.
In addition, converter lining refractories other than tuyere bricks (bricks that make up the inner walls of converters) are used under extremely harsh conditions with repeated large thermal fluctuations as described above, so they are not as effective as tuyere bricks. However, high durability is required.
Similarly, refractory linings such as hot metal pretreatment containers such as torpedoes and blast furnace ladle, and ladle containers are required to have high durability because they are used under extremely harsh conditions where large thermal fluctuations are repeated.

As a technique for increasing the durability of refractories, Patent Document 1 describes a rod-shaped or It is described that a net-like solidified body is placed inside the refractory, and since the solidified body of high-strength fiber bundles is placed inside the refractory without losing its shape, the mechanical strength of the refractory is improved. It is said to improve spall resistance.
Further, Patent Document 2 describes that a unidirectional bundle or fabric made of fibers having a higher tensile strength than the refractory is adhered to a part or the entire surface of the refractory using a heat-resistant adhesive. This technology allows refractories to maintain higher strength for longer periods than before, improves the tensile strength of refractories, suppresses cracking and destruction, and extends the lifespan and reliability of refractories. There is. Specifically, fiber bundles or fabrics are bonded using phenolic resin in a direction that constrains the outer surface of nozzles through which molten steel flows, such as long nozzles, immersion nozzles, and sliding nozzles used in the continuous steel casting process. However, it is described that an oxidation-preventing base layer or an oxidation-preventing layer is provided on the surface. In these nozzles, when molten steel flows inside, thermal expansion toward the outside is restrained by the fiber bundles or fabrics, which creates compressive stress in the refractory material that makes up the nozzle, preventing cracking and destruction. It is thought that it is being suppressed.

Japanese Patent Application Publication No. 2005-320196 Japanese Patent Application Publication No. 2007-106618

However, as a result of studies conducted by the present inventors, even if carbon fibers are arranged in refractories in the form shown in Patent Documents 1 and 2, steelmaking containers (such as converters and It was found that sufficient durability could not be obtained as a refractory for use in hot metal pretreatment containers, etc.
In addition, the technology described in Patent Document 1 places a rod-shaped or net-shaped solidified body of high-strength fiber bundles solidified with resin, pitch, etc. in a refractory, so the refractory raw material is compression molded or poured. During molding or construction, the solidified material acts as resistance and prevents the uniform compression and inflow of refractory raw materials, resulting in a decrease in the strength and fracture energy of the refractory, and a decrease in the durability of the refractory. There is.

In addition, in the continuous casting process in which the nozzle described in Patent Document 2 is used, multiple charges of molten steel blown in a converter are continuously cast, so the temperature change cycle of the nozzle used is The outer surface of the nozzle receives radiation from the molten steel stored in the downstream container located below, so the temperature difference between the molten steel flowing inside the nozzle and the molten steel flowing inside the nozzle is It's not that big. On the other hand, the refractory linings of converters and hot metal pretreatment vessels (particularly the tuyere bricks that make up the tuyeres of converters) are used under extremely harsh conditions as mentioned above. According to the studies conducted by the present inventors, it was found that the technique described in Patent Document 2 cannot sufficiently increase the durability of such refractories.

Therefore, it is an object of the present invention to solve the problems of the prior art as described above, and to solve the problems of the prior art when used under conditions where temperature rises and falls are repeated over a long period of time, such as lined refractories of converters and hot metal pretreatment vessels. To provide a graphite-containing refractory that can obtain high durability even when used under conditions with a very large internal temperature gradient, such as the tuyere bricks of a converter. be. Another object of the present invention is to provide a steelmaking container equipped with a graphite-containing refractory having such high durability.

As a result of repeated studies in order to solve the above problems, the present inventors have discovered that a specific carbon fiber fabric can be embedded in a predetermined form inside a refractory, preferably carbon fibers constituting the carbon fiber fabric. By optimizing the diameter, number, and density of carbon fibers in the cross section of the refractory, the fracture energy of the refractory is greatly improved compared to conventional technology, resulting in high durability even in the extremely harsh usage environments mentioned above. It was found that it was possible to obtain
The present invention was made based on such knowledge and has the following gist.

[1] A graphite-containing refractory in which a carbon fiber fabric (B) in which carbon fiber bundles (b) are woven in two or more directions is embedded inside a graphite-containing refractory body (A),
The carbon fiber fabric (B) contains an adhesive component (c) in the carbon fiber bundle (b), and is adhered or adhered to the refractory body (A) via the adhesive component (c),
The carbon fiber bundles (b) in the same direction constituting the carbon fiber fabric (B) have an interval between adjacent carbon fiber bundles (b) larger than the maximum particle size of the aggregate constituting the refractory body (A),
A graphite-containing refractory characterized in that, in a cross-section of the refractory in the plane direction of the carbon fiber fabric (B), the area ratio of the carbon fiber fabric (B) to the cross-sectional area of the refractory is 20% or more.

[2] The graphite-containing refractory of [1] above is characterized in that the carbon fiber fabric (B) is embedded inside the refractory body (A) along a direction perpendicular to the operating surface of the refractory. Graphite-containing refractories.
[3] The graphite-containing refractory according to [1] or [2] above, wherein the thickness of the carbon fiber fabric (B) is 0.1 mm or more and 3 mm or less.
[4] In any of the graphite-containing refractories set forth in [1] to [3] above, two or more layers of carbon fiber fabric (B) are buried at intervals within the refractory body (A). Characteristic graphite-containing refractories.
[5] In the graphite-containing refractory of [4] above, two or more layers of carbon fiber fabrics (B) are buried in parallel at intervals, and the spacing between adjacent carbon fiber fabrics (B) is 10 mm or more. A graphite-containing refractory characterized by:

[6] In any of the graphite-containing refractories according to [1] to [5] above, the carbon fiber bundles (b) in the same direction constituting the carbon fiber fabric (B) are different from the adjacent carbon fiber bundles (b). A graphite-containing refractory characterized by a spacing of more than 3 mm.
[7] The graphite-containing refractory according to any one of [1] to [6] above, characterized in that the width of the carbon fiber bundle (b) constituting the carbon fiber fabric (B) is more than 1 mm and less than 15 mm. Graphite-containing refractories.
[8] In the graphite-containing refractory according to any one of [1] to [7] above, the adhesive component (c) is an organic substance with a residual carbon content of 6% by mass or more and 80% by mass or less. Graphite-containing refractories.

[9] In the graphite-containing refractory according to any one of [1] to [8] above, the refractory body (A) is characterized in that the content of graphite raw material is 1% by mass or more and 80% by mass or less. Graphite-containing refractories.
[10] In the graphite-containing refractory according to any one of [1] to [9] above, the refractory body (A) is characterized in that the content of magnesia raw material is 20% by mass or more and 99% by mass or less. Graphite-containing refractories.
[11] In the graphite-containing refractory according to any one of [1] to [10] above, the refractory body (A) is characterized in that the content of the alumina raw material is 10% by mass or more and 95% by mass or less. Graphite-containing refractories.
[12] In the graphite-containing refractories according to any of [1] to [9] and [11] above, the refractory body (A) has a silica raw material content of 1% by mass or more and 50% by mass or less. A graphite-containing refractory characterized by:

[13] The graphite-containing refractory according to [11] or [12] above, wherein the refractory body (A) has a silicon carbide raw material content of 1% by mass or more.
[14] In the graphite-containing refractory according to any one of [1] to [13] above, the refractory body (A) is made of refractory scrap obtained by pulverizing used refractories and contains 10% by mass or more of 90% by mass as a refractory raw material. A graphite-containing refractory characterized by containing less than % by mass.
[15] A converter comprising the graphite-containing refractory according to any one of [1] to [14] above.
[16] A hot metal pretreatment vessel characterized by comprising the graphite-containing refractory according to any one of [1] to [14] above.
[17] A ladle container comprising the graphite-containing refractory according to any one of [1] to [14] above.

Since the graphite-containing refractory of the present invention has high fracture energy, it has high durability even when used under conditions where the temperature is repeatedly raised and lowered over a long period of time, such as in the refractory lining of converters and hot metal pretreatment vessels. In addition, high durability can be obtained especially when used in conditions where the internal temperature gradient is extremely large, such as in converter tuyere bricks.

One embodiment of the graphite-containing refractory of the present invention is schematically shown, and FIG. 1(A) is a side view, and FIG. 1(B) is a sectional view taken along line II in FIG. 1(A). (Cross-sectional view parallel to the refractory operating surface) A cross-sectional view along the II-II line in Figure 1 (A) (a cross-sectional view of the refractory in the plane direction of the carbon fiber fabric B) A flow diagram showing an example of the manufacturing process of the graphite-containing refractory of the present invention This figure shows a method for measuring the bending strength of graphite-containing refractories in Examples, and FIG. 4 (A) is an explanatory diagram schematically showing the implementation status of a three-point bending strength test, and FIG. ) is an explanatory diagram schematically showing the end face of a test piece. A drawing showing an example of the fracture energy determined from the load-displacement curve obtained in the three-point bending strength test in the example. This shows a test method for evaluating the erosion resistance of graphite-containing refractories in Examples, and FIG. 6(A) is an explanatory diagram schematically showing the test implementation status in a longitudinal section of a test furnace and a cylindrical sample. FIG. 6(B) is a plan view of the cylindrical sample shown in FIG. 6(A), and FIG. 6(C) is a plan view of one of the test pieces constituting the cylindrical sample shown in FIGS. 6(A) and (B). Perspective view shown

The graphite-containing refractory of the present invention is a graphite-containing refractory in which a carbon fiber fabric B is embedded (arranged) inside a refractory body A containing graphite under specific conditions.
Figures 1 and 2 schematically show an embodiment of the graphite-containing refractory of the present invention, with Figure 1 (A) being a side view and Figure 1 (B) being I- It is a cross-sectional view along the I line (a cross-sectional view parallel to the working surface of the refractory), where x is the working surface of the refractory (y is the counter-working surface). Further, FIG. 2 is a cross-sectional view (a refractory cross-sectional view in the plane direction of the carbon fiber fabric B) taken along the line II-II in FIG. 1(A). In the graphite-containing refractory of this embodiment, three layers of carbon fiber fabric B are embedded within a refractory body A at intervals.

Hereinafter, the structure of the carbon fiber fabric B and its embedding conditions (form) will be explained.
As shown in FIG. 2, the carbon fiber fabric B is a sheet-like member (woven fabric) formed by weaving carbon fiber bundles b in two or more directions (that is, oriented in two or more directions and knitting). Although the number of orientations of the carbon fiber bundles b is arbitrary, the carbon fiber fabric B of this embodiment is constructed by orienting the carbon fiber bundles b in two orthogonal directions and weaving them together. Note that if the carbon fiber bundle b is oriented in one direction, a carbon fiber fabric cannot be formed, and therefore a graphite-containing refractory in which a carbon fiber fabric is embedded cannot be obtained.
The carbon fiber fabric B is buried (arranged) inside the refractory body A, but as shown in the "enlarged cross-sectional view in the width direction of the carbon fiber bundle b" in FIG. It contains the agent component c and is embedded (arranged) in the refractory body A in a state where it is adhered or in close contact with the refractory body A via the adhesive component c.

Here, the carbon fiber fabric B is integrated as a bundle by the carbon fiber bundle b containing the adhesive component c in the bundle, and is also bonded to the refractory body A through the adhesive component c. By adhering or coming into close contact with the refractory, the carbon fibers are integrated with the refractory, which provides high fracture energy that can suppress the occurrence of cracks. In particular, when a sticky organic substance (organic resin liquid, etc.) is used as the adhesive component c, the adhesive (tackifier) imparts tackiness to the carbon fibers, causing the carbon fibers to become sticky. In addition to bundling the fiber bundles b, it is possible to improve the adhesion between the refractory and the carbon fibers when the refractory is formed, which is more effective in suppressing defects such as cracks.
Note that preferable conditions for the adhesive component c will be detailed later.

The arrangement of the carbon fiber fabric B inside the refractory body A is arbitrary and there are no special restrictions, but since the tensile stress that causes cracks is generated in the longitudinal direction of the refractory during operation, it is preferable to place it in one direction. It is preferable to arrange (buried) linearly along the direction, and particularly preferably to arrange (buried) along the direction orthogonal to the refractory operating surface x. Note that the carbon fiber fabric B may be composed of two or more fabrics stacked one on top of the other.
The ends of the carbon fiber fabric B buried inside the refractory body A may or may not be exposed on the surface of the refractory body A. In the latter case, on the working surface x side of the refractory, it is preferable that the distance between the end of the carbon fiber fabric B and the working surface x is as small as possible; The distance between the end of y and the counter-movement surface y may be large to some extent. This is because the carbon fiber fabric B does not need to be buried in the portion on the non-working surface y side of the refractory, which is expected to remain even after the end of use.

Carbon fiber bundles b in the same direction (carbon fiber bundles b woven in the same direction) constituting the carbon fiber fabric B have a distance L between adjacent carbon fiber bundles b (L ₁ , L ₂ in FIG. 2) that is fireproof. It is woven so that the particle size is larger than the maximum particle size of the aggregate that makes up the main body A. By making the interval L (L ₁ , L ₂ ) between the carbon fiber bundles b larger than the maximum particle size of the aggregate raw material in this way, it is possible to improve the intertwining of the carbon fiber fabric and the aggregate raw material, and the lamination is prevented during molding. It is possible to maintain high destructive energy without causing damage. Here, the distance L between the carbon fiber bundles b is the distance between the outer surfaces of the carbon fiber bundles b, as shown as L ₁ and L ₂ in FIG. 2 .
Moreover, it is preferable that the interval L (L ₁ , L ₂ in FIG. 2) between adjacent carbon fiber bundles b is more than 3 mm. This allows not only the above-mentioned coarse particles but also fine particles to be entangled with the carbon fiber fabric B, and also to prevent peeling caused by carbon fiber bundles called lamination during molding. Although there is no particular upper limit to the distance L (L ₁ , L ₂ in FIG. 2), it is generally preferable to set the upper limit to about 50 mm, considering the relationship with the density of carbon fibers described below.

In addition, the carbon fiber fabric B is buried (arranged) inside the refractory body A so that the area ratio of the carbon fiber fabric B to the cross-sectional area of the refractory is 20% or more in the cross section of the refractory in the plane direction. ) to be done. Here, the area occupied by the carbon fiber fabric B is the area determined by w1×w2 shown in FIG. By setting the area ratio of the carbon fiber fabric B to the cross-sectional area of the refractory to 20% or more in this way, fracture energy can be increased and crack extension can be appropriately suppressed. Moreover, from such a viewpoint, it is more preferable that the area ratio of the carbon fiber fabric B to the cross-sectional area of the refractory is 40% or more.

If the thickness of the carbon fiber fabric B is too small, the fracture energy will be difficult to increase, and the effect of suppressing crack growth will be relatively low. On the other hand, if the thickness is too large, the carbon fiber bundles b constituting the carbon fiber fabric B tend to cause springback (repulsion after compression) during molding. Therefore, the thickness of the carbon fiber fabric B is preferably 0.1 mm or more and 3 mm or less.
Further, like the graphite-containing refractory of this embodiment, the carbon fiber fabric B may be buried (arranged) in two or more layers at intervals in the thickness direction, depending on the thickness of the refractory body A. preferable. Usually, in this case, two or more layers of carbon fiber fabric B are buried in parallel at intervals. In this way, by embedding a plurality of layers of carbon fiber fabric B depending on the thickness of the refractory body A, it is possible to more appropriately obtain the effect of suppressing crack extension due to an increase in fracture energy.
In addition, when two or more layers of carbon fiber fabrics B are buried in parallel at intervals, if the interval between adjacent carbon fiber fabrics B is too small, springback is likely to occur during molding. It is preferable that the interval between B is 10 mm or more. Here, the distance between adjacent carbon fiber fabrics B is the distance between the outer surfaces of the carbon fiber fabrics B.

Moreover, it is preferable that the width w of the carbon fiber bundle b constituting the carbon fiber fabric B is more than 1 mm and less than or equal to 15 mm. Here, the width w of the carbon fiber bundle b is the length of the long side or major axis of the carbon fiber bundle b in the cross section in the width direction (however, if the cross section in the width direction is rectangular or circular, refers to the length of one side or diameter). By setting the width w of the carbon fiber bundle b to be more than 1 mm, the number of weaves of the carbon fiber bundle b can be reduced when using the same number of carbon fibers, so that the bulk of the carbon fiber fabric B due to weaving of the carbon fiber bundle b can be reduced. Tension can be suppressed and the tensile strength unique to carbon fiber fabrics can be utilized. On the other hand, since the width w of the carbon fiber bundle b is 15 mm or less, the carbon fiber bundle b may interfere with the coarse grain material of the raw material used for the refractory body A, or the carbon fiber bundle b itself may be damaged by fire. It can reduce the possibility of things becoming a trigger for melting and damage.

The carbon fiber fabric used in the present invention is one in which carbon fiber bundles of carbon fibers are woven into bundles, and usually has a mass per 1 m ² (however, the carbon fiber fabric has a mass of two or more stacked In the case of a woven fabric, the total mass of multiple stacked woven fabrics is approximately 40 to 1,300 g, the fiber diameter of the carbon fibers is approximately 1 to 45 μm, and the number of carbon fibers per carbon fiber bundle is approximately 40 to 1,300 g. Approximately 1,000 to 300,000 pieces are used. Furthermore, if the number (density) of carbon fibers arranged in the refractory body A is too small, the contact area between the refractory raw material and the carbon fiber bundle becomes small, and the effect of the present invention is relatively reduced. On the other hand, if the number of carbon fibers (density of presence) becomes too large, the carbon fiber bundle is likely to cause springback during molding, so the number of carbon fibers (density of presence) arranged in the refractory body A should be adjusted to an appropriate level. It is preferable to set it as a range. Specifically, the carbon fiber fabric B usually contains carbon in a refractory cross section in a direction perpendicular to the surface direction of the carbon fiber fabric B (usually a refractory cross section parallel to the working surface x of the graphite-containing refractory). It is preferable that the carbon fibers constituting the fiber fabric B are buried inside the refractory body A so that the existing density (embedding density) is about 10 to 2000 fibers/mm ² .

As described above, in the present invention, the carbon fiber fabric B buried (arranged) inside the refractory body A is such that the distance between adjacent carbon fiber bundles b is smaller than the maximum particle diameter of the aggregate constituting the refractory body A. (i) By satisfying the following conditions: the thickness of the carbon fiber fabric B is 0.1 mm or more and 3 mm or less; (ii) the width of the carbon fiber bundle b constituting the carbon fiber fabric B is more than 1 mm and less than 15 mm; , as the adhesion between the refractory raw material and the carbon fiber fabric further increases, the refractory (bricks) tends to become denser during molding, and the fracture energy increases significantly. Since the amount of gas escaping can be suppressed, the occurrence of cracks can be suppressed.

The adhesive component c is preferably an organic substance such as an organic resin or/and inorganic fine particles such as alumina or silica. In the case of an organic substance, the residual carbon content is preferably 6% by mass or more and 80% by mass or less.
When a refractory is used (in actual operation), the inside reaches a high temperature of 500°C or higher (measured at 900°C according to JIS K6910). At this time, even in environments where there is almost no oxygen inside, such as with graphite-containing refractories, if the adhesive component c is an organic substance, some of the adhesive attached to the carbon fiber fabric will decompose or evaporate into gas. and dissipates outside the refractory. The residual carbon percentage is considered to be an indicator of the proportion of the weight of the adhesive that remains without being gasified and dissipated, and varies depending on the type and quality of the adhesive. In the present invention, we conducted an investigation based on the idea that the residual carbon content of the adhesive affects the fracture energy when a graphite-containing refractory made of carbon fiber fabric is exposed to high temperatures, which is the actual usage environment. It has been found that when an adhesive (organic substance) with a charcoal content of 6 to 80% by mass is used, the fracture energy tends to increase. This is because when an adhesive (organic material) with such a specific carbon residual ratio is used, the adhesion between the refractory raw material (refractory body A) and the carbon fiber fabric B increases, which causes the refractory brick to become dense during molding. This is thought to be due to the fact that in addition to being easier to crack, it is possible to suppress the amount of gas escaping from the inside of the refractory when exposed to high temperatures, thereby suppressing the occurrence of cracks and increasing the fracture energy.
Furthermore, in the present invention, it has been found that high fracture energy can be obtained even when the adhesive component c is inorganic fine particles such as alumina or silica. This is because even when inorganic fine particles (particularly inorganic fine particles derived from inorganic sol) are used, the adhesion between the refractory raw material (refractory body A) and the carbon fiber fabric B increases, so the refractory brick becomes dense during molding. This is thought to be because, in addition to being easier to use, the inorganic fine particles are sintered when exposed to high temperatures during use, suppressing the occurrence of cracks and increasing fracture energy.

When the adhesive component c is organic, if the residual carbon content is less than 6% by mass, the amount of gas that escapes from the inside of the refractory increases at high temperatures, and many defects such as pores are generated, resulting in an increase in fracture energy. Hateful. On the other hand, when the residual carbon content exceeds 80% by mass, the amount of gas escaping from the inside of the refractory at high temperatures is almost gone, and the refractory becomes too dense and brittle, making it difficult to increase the fracture energy. Further, from the above viewpoint, the residual carbon content of organic matter is preferably 20 to 80% by mass, more preferably 40 to 80% by mass.
As shown in FIG. 2, the adhesive component c exists (infiltrates) within the carbon fiber bundle (in the gaps between the carbon fibers), integrates the carbon fiber bundle B as a bundle, and Since the carbon fiber bundle B is to be adhered or brought into close contact with the refractory body A by covering the outer surface, it is desirable that the adhesive used be in a liquid state. In addition, adhesive component c needs to remain without decomposition or evaporation even at high temperatures, but when used in graphite-containing refractories, combustion due to oxygen hardly occurs, so it has high flammability in the presence of oxygen. It is possible to use resin. Based on these conditions, the adhesive component c is selected from organic resins (organic resins derived from organic resin solutions), organic substances derived from tar and/or pitch, organic substances derived from organic glue, and inorganic fine particles derived from inorganic sol. More than one species (ie, any of these or mixtures thereof) are suitable.

Therefore, examples of the adhesive (tackifier) to be applied to the carbon fiber bundle during production include organic resin (solution), pitch, tar, organic glue, and inorganic sol. Specifically, phenolic resin, epoxy resin, melamine resin, urea resin, alkyd resin, unsaturated polyester resin, polyurethane resin, thermosetting polyimide resin (resin solution consisting of one or more of these organic resins), pitch, Examples include tar, starch paste, alumina sol, silica sol, zirconia sol, chromia sol, titania sol, magnesia sol, calcia sol, and yttriazole, and one or more selected from these can be used.
Additionally, these adhesives can be diluted with a solvent to adjust their viscosity during manufacturing, but the use of solvents (e.g., water) that gasify even in the absence of oxygen at high temperatures of 500°C or higher is not recommended for adhesive components. It is desirable to keep the amount equal to or less than the weight of the

Next, the composition of the refractory body A will be explained.
It is preferable that the refractory body A contains graphite raw material in an amount of 1% by mass or more and 80% by mass or less. By setting the content of the graphite raw material to 1% by mass or more, the cracking resistance of the graphite-containing refractory can be ensured, and the oxidation loss of carbon fibers inside the refractory can be suppressed. On the other hand, by controlling the content of the graphite raw material to 80% by mass or less, oxidation loss of the graphite raw material on the surface of the refractory can be suppressed. As the graphite (carbon raw material), scaly graphite or the like is generally used. Examples of refractories in which the refractory body A contains 1 to 80% by mass of graphite raw materials include, for example, magnesia-carbon refractories, which are refractories whose main components are magnesia and carbon (magnesia raw materials are used as aggregates). Alumina, silicon carbide, silica, and carbon refractories, which are refractories whose main components are alumina, silicon carbide, silica, and carbon (refractories containing alumina, silicon carbide, and silica) Graphite-containing refractories), alumina, silicon carbide, and carbon-based refractories, which are refractories whose main components are alumina, silicon carbide, and carbon (graphite-containing refractories using alumina raw materials and silicon carbide raw materials as aggregates), silica, Silica/silicon carbide/carbon refractories (silica raw materials, graphite-containing refractories using silicon carbide raw materials as aggregates), alumina/silicon carbide/silica/carbon refractories, which are refractories whose main components are silicon carbide and carbon. Examples include refractories that use refractory waste as part of the aggregate raw material.

In general, the lining (including the tuyeres) of converters used in the refining process is made of magnesia-carbon refractories, which are refractories whose main components are magnesia and carbon. refractories) are used. When the refractory body A is a magnesia-carbon refractory, the refractory body A preferably contains 20% by mass or more and 99% by mass or less of magnesia raw material, thereby suppressing cracking due to thermal spalling, and It can be made into a refractory that has corrosion resistance that can withstand the erosion of converter slag containing a large amount of. As the magnesia raw material, it is preferable to use a highly purified magnesia raw material having a magnesia concentration of 90% by mass or more.

In general, the lining of hot metal pretreatment containers (torpedo, blast furnace pot, etc.) used in the hot metal pretreatment process is made of alumina, silicon carbide, and carbon refractories, which are refractories whose main components are alumina, silicon carbide, and carbon. Alumina, silicon carbide, silica, and carbon refractories (alumina, silicon carbide, silica, and carbon refractories), which are refractories whose main components are alumina, silicon carbide, silica, and carbon raw materials, silicon carbide raw materials, graphite-containing refractories using silica raw materials as aggregates), etc. are used.
When the refractory body A is an alumina/silicon carbide/carbon refractory or an alumina/silicon carbide/silica/carbon refractory, it is preferable that the alumina raw material is contained in an amount of 10% by mass or more and 95% by mass or less. High corrosion resistance against treated slag can be obtained, and the occurrence of cracks due to thermal spalling can be further suppressed. As the alumina raw material, it is preferable to use a high purity alumina raw material with an alumina concentration of 70% by mass or more.

Furthermore, when the refractory body A is an alumina/silicon carbide/carbon refractory or an alumina/silicon carbide/silica/carbon refractory, it is preferable to contain 1% by mass or more of the silicon carbide raw material. By containing 1% by mass or more of the silicon carbide raw material, oxidation of graphite in the atmosphere can be suppressed, so that high cracking resistance can be maintained. Note that as the silicon carbide raw material, it is preferable to use a highly purified silicon carbide raw material having a silicon carbide concentration of 80% by mass or more.
In addition, when the refractory body A is made of alumina, silicon carbide, silica, or carbon refractory, it is preferable that the silica raw material is contained in an amount of 1% by mass or more and 50% by mass or less, thereby achieving high cracking resistance and high erosion resistance. I can do both.

The magnesia-carbon refractories used for the lining of converters are susceptible to extremes such as mechanical impact from the charge, abrasion due to agitation of molten steel and molten slag, slag erosion due to molten slag, and rapid temperature changes during converter operation. used under harsh conditions. Therefore, in order to ensure stable operation, it is preferable to use magnesia-carbon refractories, which have high durability and can withstand harsh conditions. Similarly, alumina/silicon carbide/carbon refractories and alumina/silicon carbide/silica/carbon refractories used for lining hot metal pretreatment vessels such as topedoes and blast furnace pots are used under extremely harsh conditions. Therefore, it is preferable to use a refractory that can withstand these conditions. According to the present invention, the fracture energy of graphite-containing refractories used under these extremely harsh conditions is significantly improved compared to conventional graphite-containing refractories, so that high durability can be obtained.

In addition, if the refractory body A is a silica/silicon carbide/carbon refractory, which is a refractory whose main components are silica, silicon carbide, and carbon, the silicon carbide raw material is 1% by mass or more, and the silica raw material is 1% by mass or more. The content is preferably 50% by mass or less, thereby achieving both high cracking resistance and high erosion resistance. By containing 1% by mass or more of the silicon carbide raw material, oxidation of graphite in the atmosphere can be suppressed, so that high cracking resistance can be maintained. Note that as the silicon carbide raw material, it is preferable to use a highly purified silicon carbide raw material having a silicon carbide concentration of 80% by mass or more.

Here, as the alumina raw material, for example, one or more types of aluminum shale, white alumina, brown alumina, etc. are used. Further, as the silicon carbide raw material, for example, one or more types of green silicon carbide, black silicon carbide, etc. are used. Further, as the silica raw material, for example, one or more types of waxite, mullite, etc. are used.
The graphite-containing refractory can further contain (mix) a metal powder raw material for the purpose of increasing durability while suppressing the amount of heat released from the steel container. Examples of the metal powder raw material include metal Si, metal Al, metal Al-Si, Al ₄ SiC ₄ and B ₄ C, and one or more of these can be contained. The content of the metal powder raw material is not particularly limited, but is usually preferably about 1 to 5% by mass. If the content (amount) of the metal powder raw material is less than 1% by mass, the effect of improving durability by blending the metal powder raw material cannot be sufficiently obtained, while on the other hand, if it exceeds 5% by mass, the strength will increase. If this is too high, cracks may easily occur when used in an actual machine, making the bricks more likely to break, which may reduce the number of times the brick can be used in an actual machine.

The refractory body A can contain approximately 10% by mass or more and 90% by mass or less of refractory waste obtained by crushing used refractories as an aggregate raw material. In particular, if the refractory body A is an alumina, silicon carbide, or carbon refractory (including alumina, silicon carbide, silica, or carbon refractories containing silica raw materials; the same shall apply hereinafter), the used Refractory waste obtained by crushing alumina, silicon carbide, and carbon refractories (including alumina, silicon carbide, silica, and carbon refractories containing silica raw materials; the same shall apply hereinafter) is used as an aggregate raw material. It can be suitably used.
When refractory waste is contained in this manner, the remainder of the refractory raw material is an unused raw material (virgin raw material).

In the refractory body A made of alumina, silicon carbide, and carbonaceous refractories, the content of refractory waste obtained by crushing used alumina, silicon carbide, and carbonaceous refractories is 10% by mass or more and 90% by mass. In the case of the following, cracking resistance and erosion resistance comparable to that of a graphite-containing refractory using only virgin raw materials can be obtained. The reason for this is that refractory scrap raw materials have lower purity than virgin raw materials, but by using the refractory scrap raw materials and virgin raw materials together, the corrosion resistance of the Al ₂ O ₃ components in the refractory scrap raw materials can be improved. One example is that it is possible to suppress a significant decline. However, when the content of refractory scrap is more than 90% by mass, the content of virgin raw material is too small, so it is not possible to suppress a significant decrease in the corrosion resistance of the Al ₂ O ₃ components in the refractory scrap raw material. . Moreover, when the content of refractory scraps is less than 10% by mass, the reuse rate of the refractory scraps is too low, and the cost of processing the refractory scraps as industrial waste increases significantly.

Next, a method for producing a graphite-containing refractory of the present invention will be explained.
FIG. 3 shows an example of the manufacturing process of the graphite-containing refractory of the present invention. In this manufacturing process, an appropriate amount of binder is added and kneaded to the refractory raw material, and the kneaded material is used to infiltrate (impregnate) the inside of the carbon fiber bundle with a specified adhesive and also adhere to the outer surface of the carbon fiber fabric. The mixture is then filled into a mold and press-molded to obtain a refractory molded product. As the binder, for example, phenol resin (base resin) + hexamine (curing agent), carbon bond, ceramic bond, etc. are used.
A method of filling a kneaded material of refractory raw material into a mold together with a carbon fiber fabric (a carbon fiber fabric in which an adhesive is infiltrated (impregnated) into the inside of the carbon fiber bundle and also adhered to the outer surface; the same applies hereinafter) is as follows: For example, there is a method in which a certain amount of the kneaded material is charged into a mold, a carbon fiber fabric is placed (charged), and a certain amount of the kneaded material is further charged into the mold. Therefore, in order to manufacture a graphite-containing refractory in which multiple layers of carbon fiber fabric B are embedded inside the refractory body A as shown in Fig. 1 using this method, after charging a certain amount of kneaded material into the mold, , the step of placing the carbon fiber fabric thereon, and the step of charging a certain amount of the kneaded material thereon are repeated.

In addition, in order to infiltrate (impregnate) and adhere an adhesive (tackifying agent) to a carbon fiber fabric, for example, the carbon fiber fabric may be immersed in a resin (resin solution) or an inorganic sol that constitutes the adhesive. By spraying the resin (resin solution) or inorganic sol that makes up the adhesive onto the carbon fiber fabric, the adhesive penetrates and adheres to the carbon fiber fabric, and the carbon fiber with this adhesive permeating and adhering to it. The woven fabric is charged into a mold together with the kneaded material in the manner described above. Here, even if the adhesive that has penetrated and adhered to the carbon fiber fabric has been cured or solidified to some extent when the carbon fiber fabric is placed in the kneaded material, the carbon fiber fabric and the refractory (kneaded material) may Any state is sufficient as long as it has adhesiveness that allows for adhesion or close contact (so-called half-dried state). Another method is to prepare a carbon fiber fabric that has been cured or solidified after impregnating the carbon fiber bundle with an adhesive in advance, and then applying the adhesive to the outer surface of the carbon fiber fabric when placing it in the kneaded material. An adhesive may also be applied.

Press molding can be performed by general mold press molding in which compression is performed in one direction within a mold, but CIP molding in which pressure is applied evenly from all directions using a liquid may also be performed. For shapes where it is difficult to apply uniform pressure by unidirectional compression, such as shapes where the thickness varies depending on the part, CIP molding is desirable because it reduces the unevenness in the degree of compression depending on the part.
Further, the molding step may be performed by a molding method other than press molding. Forming methods other than press molding include, for example, pouring. One of these methods is to install an inner frame at the construction site, which is the working surface of a pot or tundish, and to inject monolithic refractories ( There is a method in which the inner frame is removed after pouring refractory materials (refractory raw materials), drying (drying process) and solidifying. In addition, instead of pouring it into the construction site, monolithic refractories (refractory raw materials) are poured into the refractory-shaped formwork, dried (drying process), solidified, and then removed from the formwork. There is also a method of transporting the refractory to the construction site, and although this method requires more time and effort to install the refractory at the construction site, it is easier to embed the carbon fiber fabric when pouring the monolithic refractory into the formwork and to control the temperature during solidification. This is desirable because it is easy. In these molding methods by pouring, the carbon fiber fabric is placed inside the inner frame or formwork described above, and then the monolithic refractory (refractory raw material) is poured into the inner frame or formwork and dried (drying process).・Solidify.

The refractory molded product obtained as described above is dried. This drying is usually carried out at about 200 to 230°C for the purpose of drying (curing) the refractory molded product.
In addition, for refractory molded bodies obtained by casting as described above, the refractory molded bodies held in the inner frame installed at the construction site or the formwork installed at other locations are heated using a heating burner, etc. It is dried and solidified by heating with a heating means. After that, the inner frame is removed and the mold is taken out.

As described above, the carbon fiber fabric B is a graphite-containing refractory in which the carbon fiber fabric B is placed (embedded) inside the refractory body A under predetermined conditions, and the carbon fiber fabric B has the adhesive component c in the carbon fiber bundle b. The graphite-containing refractory of the present invention is obtained which is adhered or adhered to the refractory main body A via the adhesive component c.
The graphite-containing refractory of the present invention can be used as a refractory for various equipment and containers, and is particularly suitable as a lining refractory for steelmaking containers (refining containers and transportation containers) used in steel plants. Examples of iron-making containers to which the graphite-containing refractory of the present invention can be suitably applied as a lining include hot metal pretreatment containers such as converters, torpedo cars, and blast furnace ladle, ladle containers, and the like. Moreover, among these, it is suitable as a lining refractory for a converter, which is used in a particularly harsh environment, and among these, it is particularly suitable as a tuyere brick constituting a tuyere portion.

In order to study the composition of magnesia/carbonaceous raw materials for magnesia/carbonaceous refractories (graphite-containing refractories using magnesia raw materials as aggregate) used in converters, magnesia raw materials were mixed with the raw material composition shown in Table 1. We produced a refractory molded product using aggregate, that is, a graphite-containing refractory without embedded carbon fiber fabric. When kneading and molding the refractory raw material, 3% by mass of phenol resin and 0.3% by mass of hexamine were added as binders to the refractory raw material. The produced graphite-containing refractories were evaluated for erosion resistance and cracking resistance using the following methods. The results are also shown in Table 1.

Regarding the erosion resistance, as shown in FIG. 6 (test method), the amount of erosion was measured by the lining method using a high-frequency induction furnace, and the evaluation was made based on the amount of erosion. In the test using the lining method, the test temperature was 1650°C, the temperature holding time was 4 hours, synthetic slag having the composition shown in Table 2 was introduced every hour, and after cooling, the amount of erosion on the operating surface was measured. Then, from the amount of erosion, an erosion index was determined, with the amount of erosion of Formulation Example 1-4 in Table 1 set as 100. In addition, FIG. 6(A) is an explanatory diagram schematically showing the test implementation status in a longitudinal section of the test furnace and the cylindrical sample, and FIG. 6(B) is an illustration of the cylindrical sample shown in FIG. 6(A). The plan view and FIG. 6(C) are perspective views showing one of the test pieces constituting the cylindrical sample shown in FIGS. 6(A) and 6(B).
For cracking resistance, the dynamic elastic modulus E ₀ in the longitudinal direction of a 150 mm x 150 mm x 300 mm sample was measured according to the ultrasonic pulse method specified in JIS R1605, and then heated at 1500°C for 10 minutes and cooled in water for 5 minutes. , the process of 10 minutes of atmospheric cooling as one cycle was repeated three times, and after the completion of these three steps, the dynamic elastic modulus _E3 was measured again using the above method, and the rate of change in the dynamic elastic modulus _E3 before and after the test was / _E0 was used as an index for evaluation.

As shown in Formulation Examples 1-2 to 1-8 in Table 1, when the graphite content is 1% by mass or more and 80% by mass or less, and the magnesia raw material content is 20% by mass or more and 99% by mass or less, The breakage resistance and cracking resistance were almost constant, but as shown in Formulation Example 1-1, when the graphite content was less than 1% by mass, the cracking resistance significantly decreased. Further, as shown in Formulation Example 1-9, when the content of the magnesia raw material is less than 20% by mass, the erosion resistance is significantly reduced. For these reasons, in order to ensure the cracking resistance of graphite-containing refractories, it is preferable that the graphite content be 1% by mass or more. It can be seen that in order to achieve both properties, it is preferable that the graphite content be 1% by mass or more and 80% by mass or less, and the content of the magnesia raw material be 20% by mass or more and 99% by mass or less.

Graphite-containing refractories of invention examples and comparative examples in which carbon fiber fabrics were embedded (arranged) inside the refractory body A were manufactured according to the procedure shown in FIG. 3. At that time, the carbon fiber fabric was dipped in phenolic resin (resin solution) as an adhesive in advance, and the carbon fiber fabric, with the phenol resin (sap solution) permeating and adhering to the inside and outside of the carbon fiber bundle, was embedded in the refractory body. . This produced graphite-containing refractory has carbon fiber fabrics B embedded along the longitudinal direction of the refractory body A (if the carbon fiber fabrics B are multiple layers, they are arranged in parallel at equal intervals), as shown in Figure 1. The carbon fiber fabric B contains an adhesive component c in the carbon fiber bundle b constituting it, and is adhered or adhered to the refractory body A via the adhesive component c. When kneading and molding the refractory raw material, 3% by mass of phenol resin and 0.3% by mass of hexamine were added as binders to the refractory raw material. The produced graphite-containing refractories were evaluated for bending strength, fracture energy, erosion resistance, and cracking resistance using the following methods.

Regarding bending strength, as shown in Figure 4 (test method), carbon fiber fabrics were buried inside the refractory body along its longitudinal direction (if there were multiple layers of carbon fiber fabrics, they were placed in parallel at equal intervals). Using a test piece (specimen size: 150 mm x 150 mm x 300 mm) that had been buried), the distance between centers was 100 mm, the load application acceleration was 0.5 mm/min, and the test was conducted in accordance with the three-point bending test method described in JIS R2213. It was measured using Note that FIG. 4(A) is an explanatory diagram schematically showing the implementation status of the three-point bending strength test, and FIG. 4(B) is an explanatory diagram schematically showing the end face of the test piece in FIG. 4(A).
Regarding the fracture energy, as shown in FIG. 5, the position where the first peak value was shown in the load-displacement curve obtained in the three-point bending strength test was used as a reference, and the area within a range of 1 mm displacement from the reference position was taken as the area.

In addition, cracking resistance and erosion resistance were evaluated using the methods described above, but as test pieces for evaluating cracking resistance, a carbon fiber fabric was embedded inside the refractory body along its longitudinal direction ( In the case of multiple layers of carbon fiber fabric, those embedded in parallel at equal intervals were used. In addition, as a test piece for evaluating erosion resistance, a carbon fiber fabric was buried perpendicularly to the surface in contact with slag or molten steel (the working surface (buried at intervals) were used.
Regarding the comprehensive evaluation of the properties of refractory bricks, when the fracture energy is 15 kJ/m2 ^or more and the cracking resistance is _0.50E3 /E0 _or more, it is "excellent" (rating: ◎), and when the fracture energy is 10 kJ / ^m2 or more and less than 15kJ/ ^m2 , cracking resistance is _0.40E3 / _E0 or more and less than 0.50E3 _{/ E0} is "good" (rating: ○), and fracture energy is less than 10kJ/ ^m2 . If the cracking resistance was less than 0.40E ₃ /E ₀ or if a carbon fiber fabric could not be formed, it was rated “poor” (evaluation ×).

Tables 3 to 9 show the composition and characteristics (bending strength, fracture energy, , erosion resistance, cracking resistance).
In these Examples, the refractory main body had the composition of Formulation Examples 1-4 in Table 1, and the maximum particle size of the aggregate (magnesia raw material) constituting the refractory main body A was 3 mm.
First, the example in Table 3 shows the number of orientation directions of carbon fiber bundles constituting the carbon fiber fabric (the number of directions in which carbon fiber bundles are woven) and the number of orientation directions of the carbon fiber bundles constituting the carbon fiber fabric, and the number of directions in which the carbon fiber bundles are woven, and The area ratio of the carbon fiber fabric to the cross-sectional area (the area ratio of the carbon fiber fabric to the cross-sectional area of the refractory in the refractory cross section in the plane direction of the carbon fiber fabric) is the bending strength of the carbon fiber-containing magnesia/carbon brick. The effect on fracture energy and cracking resistance was investigated.

As shown in Invention Examples 1-1 to 1-5, when the area ratio of the carbon fiber fabric to the cross-sectional area of the refractory is 20% or more, the characteristics of the carbon fiber-containing magnesia/carbon brick are evaluated as "Excellent". Or it was “good”.
On the other hand, as shown in Comparative Example 1-1, when the area ratio of the carbon fiber fabric to the cross-sectional area of the refractory was less than 20%, the characteristics of the carbon fiber-containing magnesia-carbon brick were evaluated as "poor."
Further, as shown in Comparative Example 1-2, when carbon fiber bundles were oriented in only one direction, a carbon fiber fabric could not be formed, and therefore a brick in which a carbon fiber fabric was embedded could not be manufactured.

From these facts, if a carbon fiber fabric in which carbon fiber bundles are woven in two or more directions is embedded in a refractory body, and the area ratio of the carbon fiber fabric to the cross-sectional area of the refractory is 20% or more, the carbon fiber It was found that the fracture energy and cracking resistance of the magnesia-carbon bricks were increased. Furthermore, it has been found that when the area ratio of the carbon fiber fabric to the cross-sectional area of the refractory is set to 40% or more, the fracture energy and cracking resistance of the carbon fiber-containing magnesia-carbon brick are further increased.

The example shown in Table 4 investigates the effect of the thickness of the carbon fiber fabric embedded inside the refractory body on the bending strength, fracture energy, and cracking resistance of carbon fiber-containing magnesia/carbon bricks. .
As shown in Invention Example 1-3 and Invention Examples 2-2 to 2-4, when the thickness of the carbon fiber fabric is 0.1 mm or more and 3 mm or less, the characteristics of the carbon fiber-containing magnesia/carbon brick are evaluated as "excellent.""Met.
On the other hand, as shown in Invention Example 2-1 and Invention Example 2-5, when the thickness of the carbon fiber fabric is less than 0.1 mm or more than 3 mm, the characteristics of the carbon fiber-containing magnesia/carbonaceous brick are the same as Invention Example 1- 3 and invention examples 2-2 to 2-4.
From the above, it was found that when the thickness of the carbon fiber fabric is set to 0.1 mm or more and 3 mm or less, the fracture energy and cracking resistance of the carbon fiber-containing magnesia carbon brick can be maintained particularly high.

The example in Table 5 shows the influence of the width w of carbon fiber bundles on the bending strength, fracture energy, and cracking resistance of carbon fiber-containing magnesia/carbonaceous bricks for carbon fiber fabrics buried inside the refractory body. This is what I researched.
As shown in Invention Example 1-3, Invention Example 3-2 to Invention Example 3-5, when the width w of the carbon fiber bundle is more than 1 mm and less than 15 mm, the characteristics of the carbon fiber-containing magnesia/carbon brick are evaluated as "excellent". "Met.
On the other hand, as shown in Invention Example 3-1, when the width w of the carbon fiber bundle was 1 mm, the characteristics of the carbon fiber-containing magnesia carbon brick were slightly degraded. Furthermore, as shown in Invention Example 3-6, when the width w of the carbon fiber bundle was more than 15 mm, the characteristics of the carbon fiber-containing magnesia-carbon brick were slightly degraded.

The example in Table 6 shows the effect of the number of layers of carbon fiber fabric buried inside the refractory body (the number of buried layers) on the bending strength, fracture energy, and cracking resistance of carbon fiber-containing magnesia/carbon bricks. This is what I researched.
As shown in Invention Example 1-3 and Invention Examples 5-2 to 5-4, when the number of embedded layers of carbon fiber fabric is two or more, the evaluation of the characteristics of the carbon fiber-containing magnesia/carbon brick is “ It was excellent.
On the other hand, as shown in Invention Example 5-1, when the number of buried layers of the carbon fiber fabric was one, the evaluation of the characteristics of the carbon fiber-containing magnesia carbon brick was "good".
From the above, it was found that the carbon fiber-containing magnesia/carbonaceous brick exhibits excellent properties when the number of buried layers of the carbon fiber fabric is one, and even better properties when the number of embedded layers is two or more.

The examples in Table 7 show that the distance between two or more layers of carbon fiber fabrics (the distance between adjacent carbon fiber fabrics) is the bending strength and fracture energy of the carbon fiber-containing magnesia/carbonaceous brick. The effect on cracking resistance was investigated.
As shown in Invention Example 1-3 and Invention Examples 6-2 to 6-5, when the carbon fiber fabric is buried at a spacing of 10 mm or more, the characteristics of the carbon fiber-containing magnesia/carbon brick are evaluated as "Excellent". Met. On the other hand, as shown in Invention Example 6-1, when the carbon fiber fabric was embedded at a spacing of less than 10 mm, the characteristics of the carbon fiber-containing magnesia-carbon brick were evaluated as "good".
From the above, it was found that the carbon fiber-containing magnesia-carbon brick exhibits particularly excellent properties when the carbon fiber fabric is buried at a spacing of 10 mm or more.

The examples in Table 8 are carbon fiber bundles woven in the same direction with respect to the carbon fiber fabric buried inside the refractory body, and the distance L between adjacent carbon fiber bundles is carbon fiber-containing magnesia carbon. This study investigated the effects on the bending strength, fracture energy, and cracking resistance of bricks.
As shown in Invention Example 1-3 and Invention Example 7-1, when the distance L between adjacent carbon fiber bundles is larger than the maximum particle size (3 mm) of the aggregate constituting the refractory body, carbon fiber-containing magnesia The evaluation of the properties of the carbon brick was "excellent". On the other hand, as shown in Comparative Example 7-1, when the distance L between adjacent carbon fiber bundles is equal to or less than the maximum particle size (3 mm) of the aggregate constituting the refractory body, the characteristics of the carbon fiber-containing magnesia/carbon brick The evaluation was "poor". Incidentally, Invention Example 1-3 and Invention Example 7-1 also satisfy the preferred condition of the present invention that "the distance L between adjacent carbon fiber bundles is more than 3 mm."
From the above, when the distance L between adjacent carbon fiber bundles of the carbon fiber fabric is made larger than the maximum particle size of the aggregate constituting the refractory body, the carbon fiber-containing magnesia/carbonaceous brick exhibits particularly excellent properties. That's what I found out.

The examples in Table 9 show that the residual carbon content of the adhesive component (phenol resin) that is contained in the bundle of carbon fiber bundles constituting the carbon fiber fabric and that adheres or adheres the carbon fiber fabric to the refractory main body is This study investigated the effects on the bending strength, fracture energy, and cracking resistance of magnesia-carbon bricks.
As shown in Invention Example 1-3, Invention Example 8-2, and Invention Example 8-3, when the residual carbon percentage of the adhesive component is 6% or more and 80% or less, evaluation of the characteristics of carbon fiber-containing magnesia/carbon bricks was “excellent”. On the other hand, as shown in Invention Example 8-1, when the residual carbon content of the adhesive component was less than 6%, the characteristics of the carbon fiber-containing magnesia-carbon brick were evaluated as "good". Further, as shown in Invention Example 8-4, when the residual carbon content of the adhesive component was over 80%, the characteristics of the carbon fiber-containing magnesia-carbon brick were evaluated as "good".
From the above, when an organic substance is included in the carbon fiber bundle of the carbon fiber fabric and is used as an adhesive component for adhering or adhering the carbon fiber fabric to the refractory body, the residual carbon percentage is 6% or more and 80%. It has been found that carbon fiber-containing magnesia-carbon bricks exhibit particularly excellent properties when the following adhesive components are used.

A similar study was conducted on carbon fiber-containing graphite-containing refractories (refractory bricks) using alumina raw materials, silicon carbide raw materials, and silica raw materials as aggregates to be used for lining hot metal pretreatment containers.
The examples in Table 10 are about carbon fiber-containing alumina, silica, silicon carbide, and carbon bricks (graphite-containing refractories using alumina raw materials, silicon carbide raw materials, and silica raw materials as aggregates) used for lining hot metal pretreatment vessels. This study investigated the effects of its composition on the bending strength, fracture energy, cracking resistance, and erosion resistance of graphite-containing refractories.
In this example, carbon fiber fabrics with a spacing of 10 mm between adjacent carbon fiber bundles oriented in the same direction are buried in parallel at 30 mm intervals inside an alumina/silica/silicon carbide/carbon refractory (refractory body). did. At that time, the carbon fiber fabric is immersed in advance in a phenol resin (resin solution) with a residual carbon content of 40% by mass, which is an adhesive, and the carbon fibers with the phenol resin (resin solution) permeated and adhered to the inside and outside of the carbon fiber bundle. The fabric was embedded in the refractory body. In this example, the maximum particle size of the aggregate (alumina raw material, silicon carbide raw material, silica raw material) constituting the refractory body was set to 3 mm.

As shown in Invention Examples 9-2 to 9-8, the content of alumina raw material is 10% by mass or more and 95% by mass or less, the content of silica raw material is 1% by mass or more and 50% by mass or less, and the content of silicon carbide raw material is When the amount was 1% by mass or more and the graphite content was 1% by mass or more and 80% by mass or less, the fracture energy was high and both high cracking resistance and high erosion resistance could be achieved.
On the other hand, as shown in Invention Example 9-1, the content of the alumina raw material is less than 10% by mass, the content of the silica raw material is less than 1% by mass, the content of the silicon carbide raw material is less than 1% by mass, and the graphite content is 80% by mass. When the content exceeds % by mass, both fracture energy, cracking resistance, and erosion resistance are reduced.

Furthermore, as shown in Invention Example 9-9, the content of the alumina raw material is more than 95% by mass, the content of the silica raw material is less than 1% by mass, the content of the silicon carbide raw material is less than 1% by mass, and the graphite content is 1% by mass. If it is less than % by mass, the occurrence of cracks due to thermal spalling cannot be suppressed, resulting in a decrease in fracture energy and cracking resistance.
From the above, in carbon fiber-containing alumina/silica/silicon carbide/carbon refractories, the content of alumina raw materials should be 10% by mass or more and 95% by mass or less, and the content of silica raw materials should be 1% by mass or more and 50% by mass or less. It was found that if the content of the silicon carbide raw material is 1% by mass or more and the graphite content is 1% by mass or more and 80% by mass or less, high erosion resistance and high fracture energy/crack resistance can be achieved at the same time.

The examples in Table 11 are carbon fiber-containing alumina/silica/silicon carbide/carbon bricks (graphite-containing refractories using alumina raw materials, silicon carbide raw materials, and silica raw materials as aggregates) used for lining hot metal pretreatment vessels. Regarding graphite-containing refractories that use refractory scraps obtained by crushing used alumina, silica, silicon carbide, and carbonaceous refractories as part of the aggregate raw material, the refractory scrap content is This study investigated the effects of refractories on the bending strength, fracture energy, cracking resistance, and erosion resistance of graphite-containing refractories.
In this example, carbon fiber fabrics with a spacing of 10 mm between adjacent carbon fiber bundles oriented in the same direction are buried in parallel at 30 mm intervals inside an alumina/silica/silicon carbide/carbon refractory (refractory body). did. At that time, the carbon fiber fabric is immersed in advance in a phenol resin (resin solution) with a residual carbon content of 40% by mass, which is an adhesive, and the carbon fibers with the phenol resin (resin solution) permeated and adhered to the inside and outside of the carbon fiber bundle. The fabric was embedded in the refractory body. In this example, the maximum particle size of the aggregate (alumina raw material, silicon carbide raw material, silica raw material) constituting the refractory body was set to 3 mm.

As shown in Invention Examples 10-1 to 10-3, when the content of refractory waste is 10% by mass or more and 90% by mass or less, graphite-containing refractories using only the virgin raw materials shown in Table 10 and Similar fracture energy, cracking resistance, and erosion resistance were obtained.
On the other hand, as shown in Invention Example 10-4, when the content of refractory debris exceeded 90% by mass, fracture energy, cracking resistance, and erosion resistance decreased.
From the above, regarding carbon fiber-containing graphite-containing refractories made from refractory scraps obtained by crushing used alumina, silica, silicon carbide, and carbonaceous refractory scraps as an aggregate raw material, the content of refractory scraps It was found that if the amount is 10% by mass or more and 90% by mass or less, fracture energy can be maintained high, and furthermore, it has cracking resistance and erosion resistance comparable to graphite-containing refractories using only virgin raw materials. .

The examples in Table 12 are for carbon fiber-containing alumina/silicon carbide/carbon bricks (graphite-containing refractories using alumina raw materials and silicon carbide raw materials as aggregates), and their compositions are based on the bending strength and fracture energy of graphite-containing refractories.・The effect on cracking resistance and erosion resistance was investigated.
In this example, carbon fiber fabrics with a spacing of 10 mm between adjacent carbon fiber bundles oriented in the same direction were embedded in parallel at 30 mm intervals inside an alumina/silicon carbide/carbon refractory (refractory body). At that time, the carbon fiber fabric is immersed in advance in a phenol resin (resin solution) with a residual carbon content of 40% by mass, which is an adhesive, and the carbon fibers with the phenol resin (resin solution) permeated and adhered to the inside and outside of the carbon fiber bundle. The fabric was embedded in the refractory body. In this example, the maximum particle size of the aggregate (alumina raw material, silicon carbide raw material) constituting the refractory body was set to 3 mm.

As shown in Invention Examples 11-2 to 11-4, when the alumina raw material content is 10% by mass or more and 95% by mass or less and the graphite content is 1% by mass or more and 80% by mass or less, high bending strength and Good fracture energy, cracking resistance, and erosion resistance are achieved.
On the other hand, as shown in Invention Example 11-1, when the alumina raw material content is less than 10% by mass and the graphite content is more than 80% by mass, fracture energy, cracking resistance, and erosion resistance are reduced. Further, as shown in Invention Example 11-5, when the alumina raw material content is more than 95% by mass and the graphite content is less than 1% by mass, the fracture energy and cracking resistance are reduced.
From the above, in carbon fiber-containing alumina/silicon carbide/carbon refractories, if the alumina raw material content is 10% by mass or more and 95% by mass or less, and the graphite content is 1% by mass or more and 80% by mass or less, It was found that high fracture energy, cracking resistance, and erosion resistance can be obtained.

The examples in Table 13 are for carbon fiber-containing silica/silicon carbide/carbon bricks (graphite-containing refractories using silica raw materials and silicon carbide raw materials as aggregates), and their compositions are based on the bending strength and fracture energy of graphite-containing refractories.・The effect on cracking resistance and erosion resistance was investigated.
In this example, carbon fiber fabrics with a spacing of 10 mm between adjacent carbon fiber bundles oriented in the same direction were buried in parallel at 30 mm intervals inside a silica/silicon carbide/carbon refractory (refractory body). At that time, the carbon fiber fabric is immersed in advance in a phenol resin (resin solution) with a residual carbon content of 40% by mass, which is an adhesive, and the carbon fibers with the phenol resin (resin solution) permeated and adhered to the inside and outside of the carbon fiber bundle. The fabric was embedded in the refractory body. In this example, the maximum particle size of the aggregate (silica raw material, silicon carbide raw material) constituting the refractory body was set to 3 mm.

As shown in Invention Examples 12-2 to 12-4, when the content of the silica raw material is 1% by mass or more and 50% by mass or less, high bending strength, fracture energy/cracking resistance, and erosion resistance are obtained. ing.
On the other hand, as shown in Invention Example 12-1, when the content of the silica raw material is less than 1% by mass, the fracture energy and cracking resistance are reduced.
Further, as shown in Invention Example 12-5, when the content of the silica raw material is more than 50% by mass, the generation of cracks due to thermal spalling cannot be suppressed, and the fracture energy and cracking resistance are reduced.
From the above, in carbon fiber-containing silica/silicon carbide/carbon refractories, if the content of silica raw material is 1% by mass or more and 50% by mass or less, high bending strength, fracture energy, cracking resistance, and erosion resistance are achieved. I found out that I can get sex.

Table 14 shows that the present invention bricks of Invention Examples 1-3 (graphite-containing refractories using magnesia raw material as aggregate) and conventional bricks without embedded carbon fiber fabrics were installed at the tuyere of a converter, and the wear rate was measured. The results of the evaluation are shown. The conventional brick is a brick having the same composition and manufacturing method as the present invention brick of Invention Example 1-3, except that the carbon fiber fabric is not embedded. As shown in Table 14, the wear rate of the bricks of the present invention was reduced by more than 50% compared to the conventional bricks.
Table 15 shows that the present invention bricks of Invention Examples 1-3 (graphite-containing refractories using magnesia raw material as aggregate) and conventional bricks without embedded carbon fiber fabrics were constructed on the side wall of the slag line of the ladle. The results of evaluating the wear rate are shown. The conventional brick is a brick having the same composition and manufacturing method as the present invention brick of Invention Example 1-3, except that the carbon fiber fabric is not embedded. As shown in Table 15, the wear rate of the bricks of the present invention was reduced by more than 50% compared to the conventional bricks.

Table 16 shows that the brick of the present invention of Invention Example 9-5 (graphite-containing refractory using alumina raw material, silicon carbide raw material, and silica raw material as aggregate) and the conventional brick without embedded carbon fiber fabric were placed in a hot metal pretreatment container. This shows the results of evaluating the rate of wear and tear applied to the side wall of a certain blast furnace pot. The conventional brick is a brick having the same composition and manufacturing method as the brick of the present invention of Invention Example 9-5, except that the carbon fiber fabric is not embedded. As shown in Table 16, the wear rate of the bricks of the present invention was reduced by about 20% to 30% compared to conventional bricks.
As shown in Tables 14 to 16, it was found that when the bricks of the present invention were applied to converters, ladles, and hot metal pretreatment vessels, the wear rate of actual equipment could be significantly reduced.

A Refractory main body B Carbon fiber fabric c Adhesive component b Carbon fiber bundle x Refractory moving surface y Non-moving surface

Claims (17)

A graphite-containing refractory in which a carbon fiber fabric (B) in which carbon fiber bundles (b) are woven in two or more directions is embedded inside a graphite-containing refractory body (A),
The carbon fiber fabric (B) contains an adhesive component (c) in the carbon fiber bundle (b), and is adhered or adhered to the refractory body (A) via the adhesive component (c),
The carbon fiber bundles (b) in the same direction constituting the carbon fiber fabric (B) have an interval between adjacent carbon fiber bundles (b) larger than the maximum particle size of the aggregate constituting the refractory body (A),
A graphite-containing refractory characterized in that, in a cross-section of the refractory in the plane direction of the carbon fiber fabric (B), the area ratio of the carbon fiber fabric (B) to the cross-sectional area of the refractory is 20% or more. The graphite-containing refractory according to claim 1, characterized in that the carbon fiber fabric (B) is embedded inside the refractory main body (A) along a direction perpendicular to the operating surface of the refractory. The graphite-containing refractory according to claim 1 or 2, wherein the carbon fiber fabric (B) has a thickness of 0.1 mm or more and 3 mm or less. The graphite-containing refractory according to any one of claims 1 to 3, characterized in that two or more layers of carbon fiber fabric (B) are embedded at intervals within the refractory body (A). The graphite-containing refractory according to claim 4, characterized in that two or more layers of carbon fiber fabrics (B) are buried in parallel at intervals, and the interval between adjacent carbon fiber fabrics (B) is 10 mm or more. thing. According to any one of claims 1 to 5, wherein the carbon fiber bundles (b) in the same direction constituting the carbon fiber fabric (B) have an interval between adjacent carbon fiber bundles (b) of more than 3 mm. graphite-containing refractories. The graphite-containing refractory according to any one of claims 1 to 6, wherein the carbon fiber bundle (b) constituting the carbon fiber fabric (B) has a width of more than 1 mm and less than 15 mm. The graphite-containing refractory according to any one of claims 1 to 7, wherein the adhesive component (c) is an organic substance having a residual carbon content of 6% by mass or more and 80% by mass or less. The graphite-containing refractory according to any one of claims 1 to 8, wherein the refractory body (A) has a graphite raw material content of 1% by mass or more and 80% by mass or less. The graphite-containing refractory according to any one of claims 1 to 9, wherein the refractory body (A) has a magnesia raw material content of 20% by mass or more and 99% by mass or less. The graphite-containing refractory according to any one of claims 1 to 10, wherein the refractory body (A) has an alumina raw material content of 10% by mass or more and 95% by mass or less. 12. The graphite-containing refractory according to claim 1, wherein the refractory body (A) has a silica raw material content of 1% by mass or more and 50% by mass or less. The graphite-containing refractory according to claim 11 or 12, wherein the refractory main body (A) has a silicon carbide raw material content of 1% by mass or more. Graphite according to any one of claims 1 to 13, characterized in that the refractory body (A) contains refractory scrap obtained by pulverizing used refractories from 10% by mass to 90% by mass as a refractory raw material. Containing refractories. A converter comprising the graphite-containing refractory according to any one of claims 1 to 14. A hot metal pretreatment vessel comprising the graphite-containing refractory according to any one of claims 1 to 14. A ladle container comprising the graphite-containing refractory according to any one of claims 1 to 14.

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