JP2023166932A - Graphite-containing refractory - Google Patents

Abstract

To provide graphite-containing refractory having high durability by suppressing crack development caused by thermal stress, even when used in a condition of repeated heating up and cooling down over a long time, like the refractory liner of a converter, and having high durability, even when used in a condition of very large inner temperature gradient, particularly like tuyere bricks of the converter.SOLUTION: There is provided graphite-containing refractory in which carbon fiber fabric B is embedded along one direction, inside a refractory body A containing 1-80 mass% of graphite. The carbon fiber fabric B has mass of 40-1300 g per 1 m2, preferably, existing density of the carbon fiber forming the carbon fiber fabric B, in the refractory cross section parallel to a refractory work face, is 10-2000 pieces/mm2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a graphite-containing refractory having carbon fibers embedded therein.

Equipment (refining containers, transport containers, etc.) used in the ironmaking process and steelmaking process at a steelworks is lined with refractory material so that it can withstand long-term use at high temperatures. In general, magnesia/carbon refractories are used for the lining of converters used in the refining process, and alumina, silicon carbide, carbon refractories, etc. are used for the lining of torpedoes and blast furnace pots used in the hot metal pretreatment process. is 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 surfaces 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 also used under harsh conditions where the large thermal fluctuations described above are repeated, so although they are not as severe as tuyere bricks, High durability is required.

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, the strength is insufficient for refractories used in converters exposed to harsh conditions. was found to be insufficient.
In addition, the technology described in Patent Document 1 is a method in which a rod-shaped or net-shaped solidified body made of high-strength fiber bundles solidified with resin or pitch is placed in a refractory, so the carbon fiber bundle per unit area is If the weight is large, when the refractory raw material is compressed or poured, the solidified material acts as resistance and prevents uniform compression and flow of the refractory raw material, resulting in a decrease in the strength and failure of the refractory. There is a problem that energy is reduced and the durability of the refractory is reduced.

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 It is longer than the refractory lining of the nozzle, and 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 nozzle and the molten steel flowing inside the nozzle is not that large. On the other hand, the lining refractories of converters (the bricks that make up the inner walls of the converter), especially the tuyere bricks that make up the tuyeres, are used under very 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 caused by thermal stress even when the refractory lining of a converter is used under conditions where temperature rises and falls are repeated over a long period of time. The graphite-containing material suppresses the propagation of cracks and provides high durability, and also provides high durability even when used in conditions with extremely large internal temperature gradients, such as in converter tuyere bricks. Our goal is to provide refractories.

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. It has been found that by optimizing the diameter, number, and density of carbon fibers in the cross section of the refractory, high durability can be obtained even in the extremely harsh usage environment described above.
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) is embedded inside a refractory body (A) having a graphite content of 1 to 80% by mass,
The carbon fiber fabric (B) is a graphite-containing refractory characterized by a mass of 40 to 1,300 g per 1 m ² .
[2] In the graphite-containing refractory of [1] above, the carbon fiber fabric (B) has carbon fiber bundles (b) arranged in two directions at intervals exceeding the maximum particle diameter of the aggregate constituting the refractory body (A). It is a fabric that is woven into
The carbon fiber bundle (b) is a bundle of carbon fibers with a fiber diameter of 1 to 45 μm, and the number of carbon fibers per bundle is 1000 to 300000,
A graphite-containing refractory characterized in that the density of carbon fibers constituting the carbon fiber fabric (B) in a cross section of the refractory parallel to the working surface of the refractory is 10 to 2000 fibers/mm ² .

[3] In the graphite-containing refractory of [1] or [2] above, the carbon fiber fabric (B) is embedded inside the refractory body (A) along a direction perpendicular to the refractory operating surface. A graphite-containing refractory characterized by:
[4] In any of the graphite-containing refractories set forth in [1] to [3] above, the carbon fiber fabric (B) shall have a spacing of more than 3 mm between carbon fiber bundles (b) woven in the same direction. A graphite-containing refractory characterized by:
[5] The graphite-containing refractory according to any one of [1] to [4] above, characterized in that the carbon fiber fabric (B) is composed of one or more laminated fabrics. thing.
[6] In the graphite-containing refractory according to any of [1] to [5] above, one layer or two or more layers of carbon fiber fabric (B) are embedded inside the refractory body (A). A graphite-containing refractory characterized by:

[7] In the graphite-containing refractory of [6] above, the graphite is characterized in that the interval between two or more layers of carbon fiber fabric (B) embedded inside the refractory body (A) is 10 mm or more. Contains refractories.
[8] In the graphite-containing refractory according to any one of [1] to [7] above, the carbon fiber fabric (B) adheres to the refractory body (A) via an adhesive component, and the adhesive component is a graphite-containing refractory characterized by being one or more selected from organic resins, inorganic fine particles derived from inorganic sol, organic substances derived from tar and/or pitch, and organic substances derived from organic glue.

[9] In the graphite-containing refractory according to any one of [1] to [8] above, the refractory body (A) is characterized by containing 20 to 99% by mass of a magnesia raw material with a magnesia concentration of 90% by mass or more. Graphite-containing refractories.
[10] In the graphite-containing refractory according to any one of [1] to [8] above, the refractory body (A) is characterized by containing 10 to 95% by mass of an alumina raw material with an alumina concentration of 70% by mass or more. Graphite-containing refractories.
[11] In the graphite-containing refractory according to any one of [1] to [8] and [10] above, the refractory body (A) is a graphite-containing refractory characterized by containing 1 to 50% by mass of a silica raw material. Refractory.
[12] In the graphite-containing refractory of [10] or [11] above, the refractory body (A) is characterized by containing 1% by mass or more of a silicon carbide raw material with a silicon carbide concentration of 80% by mass or more. Graphite-containing refractories.
[13] In the graphite-containing refractory according to any one of [1] to [12] above, the refractory body (A) contains 10 to 90% by mass of refractory waste obtained by crushing used refractories. Graphite-containing refractories.

The graphite-containing refractory of the present invention has high fracture energy, so even if it is used under conditions where the temperature is repeatedly raised and lowered over a long period of time, such as in the refractory lining of a converter, it will not crack due to thermal stress. Since the growth is suppressed, high durability can be obtained, and high durability can be obtained especially when used in conditions where the internal temperature gradient is extremely large, such as in converter tuyere bricks.

In one embodiment in which the graphite-containing refractory of the present invention is applied to a tuyere brick, one of the brick constituent members constituting the tuyere brick is schematically shown, and FIG. 1(A) is a side view. , Figure 1 (a) is a cross-sectional view along line II in Figure 1 (a) (a cross-sectional view parallel to the refractory operating surface) A plan view schematically showing an embodiment of a carbon fiber fabric embedded inside a refractory body in a graphite-containing refractory of the present invention. 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 (fracture energy of the present invention example) obtained from the load-displacement curve obtained in the three-point bending strength test in the example. Drawing showing another example of fracture energy (fracture energy of comparative example) obtained 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 inside a refractory body A having a graphite content of 1 to 80% by mass, and the carbon fiber fabric B is per 1 m ² It is characterized by having a mass of 40 to 1300 g. By embedding such carbon fiber fabric B inside the refractory body A, the carbon fiber fabric B is integrated with the refractory, so that the carbon fiber fabric B does not slip inside the refractory body A. , Therefore, the fracture energy of the entire refractory increases significantly, and the effect of suppressing crack growth also improves.

FIG. 1 schematically shows an embodiment of the graphite-containing refractory of the present invention. FIG. 1(A) is a side view, and FIG. 1(B) is taken along line II in FIG. It is a sectional view (a sectional view parallel to the refractory operating surface) along which x is the refractory operating surface (y is the counter-operating surface). In the graphite-containing refractory of this embodiment, three layers of carbon fiber fabric B are embedded within a refractory body A at intervals.
Further, FIG. 2 is a plan view schematically showing an embodiment of a carbon fiber fabric B buried inside a refractory body A, and the carbon fiber fabric B of this embodiment has two carbon fiber bundles b. It is woven in such a way that it is oriented in two directions (two orthogonal directions).

The structure and embedding conditions of carbon fiber fabric B will be explained below.
The carbon fiber fabric B is made by weaving carbon fiber bundles b oriented in two or more directions, and the number of orientations is arbitrary. 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.
Carbon fiber fabric B has a mass of 40 to 1300 g per 1 m ² . Here, when the carbon fiber fabric B is composed of a plurality of laminated fabrics as described later, the mass per 1 m ² is the total mass of the laminated fabrics. If the mass of the carbon fiber fabric B is less than 40 g per 1 m ² , the carbon fiber fabric is too thin, so the crack propagation suppressing effect is not improved and the fracture energy is not increased. On the other hand, if the mass of carbon fiber fabric B exceeds 1300 g per 1 m ² , the carbon fiber fabric is too thick, and when compression molding a refractory, rebound after compression called springback may occur, or the compression force may be reduced. Uneven transmission causes defects such as internal defects in the refractory or non-uniform properties, reducing its durability. Furthermore, even when a refractory is formed by pouring rather than compression molding, uniform inflow may be hindered, or voids encapsulated or attached to the carbon fiber fabric may remain, resulting in reduced durability.

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 possible to arrange it in one direction. It is preferable to arrange (buried) in a straight line along the refractory, and particularly preferably to arrange (buried) along the direction orthogonal to the refractory operating surface x.
Note that 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-moving surface y may be large to some extent. This is because the carbon fiber fabric B does not need to be buried in the part on the non-working surface y side of the refractory, which is expected to remain even after use.

Among the carbon fiber bundles b constituting the carbon fiber fabric B, the intervals between the carbon fiber bundles b woven in the same direction are determined by the distance between the carbon fiber bundles b woven in the same direction. It is preferable to make the maximum particle size larger than the maximum particle size of the particles. That is, the carbon fiber bundles b in the same direction are preferably woven at intervals exceeding the maximum particle diameter of the aggregate constituting the refractory body A. Thereby, the aggregate (coarse particles) can enter between the stitches of the carbon fiber fabric b, and it is possible to suppress the propagation of cracks that occur along the surface of the aggregate (coarse particles).

The carbon fiber bundle b constituting the carbon fiber fabric B is a bundle of carbon fibers with a fiber diameter of 1 to 45 μm, and the number of carbon fibers per bundle is preferably 1,000 to 300,000. . If the fiber diameter of the carbon fibers constituting carbon fiber fabric B (carbon fiber bundle b) is 1 μm or more and the number of carbon fibers per bundle of carbon fiber bundle b is 1000 or more, crack growth can be suppressed to a higher degree. Effects can be obtained. On the other hand, if the fiber diameter of the carbon fibers constituting carbon fiber fabric B (carbon fiber bundle b) is 45 μm or less, and the number of carbon fibers per bundle of carbon fiber bundle b is 300,000 or less, Non-uniformity is suppressed and durability is improved.
Furthermore, if the fiber diameter of the carbon fibers constituting carbon fiber bundle b is less than 1 μm and the number of carbon fibers per bundle of carbon fiber bundle b is less than 1000, the mass per 1 m ² of carbon fiber fabric B is less than 40 g. On the other hand, when the fiber diameter of the carbon fibers constituting carbon fiber bundle b exceeds 45 μm and the number of carbon fibers per bundle of carbon fiber bundle b exceeds 300,000, the mass per 1 m ² of carbon fiber fabric B tends to exceed 1300g.

In addition, the carbon fiber fabric B is made such that the existing density (buried density) of carbon fibers constituting the carbon fiber fabric B in the refractory cross section parallel to the refractory working surface x is 10 to 2000 fibers/ ^mm2 . It is preferable to embed it inside the refractory body A. As a result, the contact area between the refractory raw material and the carbon fiber bundle b constituting the carbon fiber fabric B increases, and the adhesion between the refractory raw material and the carbon fiber fabric B also increases, resulting in a significant increase in fracture energy. Here, the existing density of carbon fibers (embedded density) refers to all of the carbon fiber bundles b that make up the carbon fiber bundle b, excluding the carbon fiber bundle b that is parallel to the refractory operating surface. It is the value obtained by dividing the number of carbon fibers (pieces) by the area (mm ² ) of the refractory cross section parallel to the refractory operating surface.
If the existing density of carbon fibers (buried density) is less than 10 fibers/ ^mm2 , the contact area between the refractory raw material and the carbon fiber bundle B is too small, and the adhesion between the refractory raw material and the carbon fiber fabric B does not increase, resulting in destruction. We cannot expect a significant increase in energy. Furthermore, if the density of carbon fibers (embedded density) exceeds 2000 fibers/ ^mm2 , the contact area between the refractory raw material and the carbon fiber bundle b is too large, and the carbon fiber bundle b tends to spring back during molding. There is a risk of causing problems.

In the carbon fiber fabric B, it is preferable that the spacing between the carbon fiber bundles b woven in the same direction is more than 3 mm. As a result, the carbon fiber fabric B is well entangled with not only the coarse particles but also the fine particles as described above, and the bending strength and fracture energy can be further increased. Here, the spacing between the carbon fiber bundles b is the distance L ₁ , L ₂ between the centers of the carbon fiber bundles b shown in FIG. 2, and if the spacing differs depending on the direction, the shorter spacing is more than 3 mm. This is desirable.
The carbon fiber fabric B is composed of one or more laminated fabrics, and when the carbon fiber fabric B is composed of two or more laminated fabrics, the number of fabrics is arbitrary. Further, the carbon fiber fabric B can be buried in one layer or two or more layers at intervals within the refractory main body A, and the number of layers in the case of two or more layers being buried is arbitrary. By increasing the number of fabrics per layer of carbon fiber fabric B or increasing the number of layers of carbon fiber fabric B, the effect of suppressing the propagation of cracks in the refractory is further improved.
In addition, when embedding two or more layers of carbon fiber fabric B inside the refractory body A, if the spacing between the layers of carbon fiber fabric B is too narrow, the carbon fiber bundles b constituting carbon fiber fabric B will spring up during molding. In order to suppress the springback of the carbon fiber bundle b, the distance between the layers of the carbon fiber fabric B is preferably 10 mm or more, since this tends to cause backing and cracks in the molded body.

It is preferable that the carbon fiber fabric B is brought into close contact with the refractory body A via an adhesive (tackifier) component, thereby increasing the adhesion between the refractory raw material A and the carbon fiber fabric B, The refractory material is easily densified during molding, and the fracture energy is greatly improved. Examples of the adhesive component (solid component) interposed between the carbon fiber fabric B and the refractory body A include organic resins, inorganic fine particles derived from inorganic sol, organic substances derived from tar and/or pitch, and organic materials derived from organic glue. Examples include organic substances, and one or more types selected from these can be used.
Therefore, examples of the adhesive (tackifier) to be applied to the carbon fiber fabric during production include organic resin (solution), inorganic sol, pitch, tar, and organic glue. Specifically, phenolic resin, epoxy resin, melamine resin, urea resin, alkyd resin, unsaturated polyester resin, polyurethane resin, thermosetting polyimide resin, alumina sol, silica sol, zirconia sol, chromia sol, titania sol, magnesia sol, calcia sol, Examples include yttriazole, pitch, tar, starch paste, etc., and one or more types selected from these can be used.

Next, the composition of the refractory body A will be explained.
The graphite content of the refractory body A is 1 to 80% by mass, and if the graphite content is less than 1% by mass, the occurrence of cracking due to thermal stress cannot be suppressed, and the cracking resistance is significantly reduced. On the other hand, if the graphite content exceeds 80% by mass, depending on the material of the refractory body A, properties such as erosion resistance, cracking resistance, and fracture energy may be adversely affected. As the graphite (carbon raw material), scaly graphite or the like is generally used.
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 to 99 mass% of a high-purity magnesia raw material with a magnesia concentration of 90 mass% or more, thereby preventing thermal spalling. It is possible to produce a refractory material that can suppress cracking due to oxidation and can also withstand erosion by converter slag. If the content of the magnesia raw material exceeds 99% by mass, cracking cannot be suppressed and the cracking resistance is significantly reduced. On the other hand, if the content of the magnesia raw material is less than 20% by mass, it will not be able to withstand the erosion of converter slag, and the erosion resistance will be significantly reduced.

In addition, the lining of torpedoes and blast furnace pots used in the hot metal pretreatment process is generally made of alumina, silicon carbide, and carbon refractories (alumina raw materials, silicon carbide), which are refractories whose main components are alumina, silicon carbide, and carbon. graphite-containing refractories whose main components are alumina, silicon carbide, silica, and carbon (alumina raw materials, silicon carbide raw materials, silica Graphite-containing refractories whose raw materials are aggregates are used. When the refractory body A is an alumina/silicon carbide/carbon refractory or an alumina/silicon carbide/silica/carbon refractory, it contains 10 to 95% by mass of a high-purity alumina raw material with an alumina concentration of 70% by mass or more. This is preferable, and as a result, it can withstand the erosion of hot metal pretreatment slag and can also suppress cracking due to thermal spalling. If the content of the alumina raw material is less than 10% by mass, it will not be able to withstand the erosion of the hot metal pretreatment slag, and the slag will penetrate into the matrix portion of the refractory body A (brick), resulting in a decrease in erosion resistance. On the other hand, if the content of the alumina raw material exceeds 95% by mass, the generation of cracks due to thermal spalling cannot be suppressed, resulting in a decrease in crack resistance.

Furthermore, if the refractory body A is an alumina/silicon carbide/carbon refractory or an alumina/silicon carbide/silica/carbon refractory, 1% by mass of a high purity silicon carbide raw material with a silicon carbide concentration of 80% by mass or more is added. It is preferable to contain the above amount. 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. If the content of the silicon carbide raw material is less than 1% by mass, oxidation of graphite in the air cannot be suppressed, resulting in a decrease in cracking resistance.
Further, when the refractory body A is an alumina/silicon carbide/silica/carbon refractory, it is preferable to contain 1 to 50% by mass of the silica raw material, thereby achieving both high cracking resistance and high erosion resistance. When the content of the silica raw material is less than 1% by mass, the amount of expansion is small and no microcracks are generated, so the thermal shock fracture resistance is not increased and the cracking resistance is likely to decrease. On the other hand, when the content of the silica raw material exceeds 50% by mass, the erosion resistance deteriorates significantly.

Magnesia-carbon refractories used for the lining of converters are susceptible to extreme damage 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 severe 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, a high-purity silicon carbide raw material with a silicon carbide concentration of 80% by mass or more is used. It is preferable to contain 1% by mass or more and 1 to 50% by mass of silica raw material, 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. If the content of the silicon carbide raw material is less than 1% by mass, oxidation of graphite in the air cannot be suppressed, resulting in a decrease in cracking resistance. Furthermore, if the content of the silica raw material is less than 1% by mass, the amount of expansion is small and no microcracks are generated, so the thermal shock fracture resistance is not increased and the cracking resistance is likely to decrease. On the other hand, when the content of the silica raw material exceeds 50% by mass, the erosion resistance deteriorates significantly.

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 to 90% by mass 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 was set to 10 to 90% by mass. In this case, cracking resistance and erosion resistance comparable to those of graphite-containing refractories 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. On the other hand, when the content of refractory scrap is more than 90% by mass, the content of the virgin raw material is too small, so it is impossible to suppress a significant decrease in the corrosion resistance of the Al ₂ O ₃ component 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.
In addition to the so-called refractory bricks manufactured through press molding, the graphite-containing refractories of the present invention include, as will be described later, those that are molded by pouring at the construction site that is the operational surface of pots, tundishes, etc. It also includes refractories that are dried and solidified.

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 to the refractory raw material and kneaded, and the kneaded product is filled into a mold together with a carbon fiber fabric 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 material into a mold together with a carbon fiber fabric is, for example, charging a certain amount of the kneaded material into a mold, charging the carbon fiber fabric, and then adding a certain amount of the kneaded material into the mold. There is a way to load it. Therefore, in order to manufacture a graphite-containing refractory in which multiple layers of carbon fiber fabric are embedded as shown in Figure 1 using this method, a certain amount of kneaded material is charged into the mold, and then the carbon fiber fabric is charged and Subsequent charging of a certain amount of kneaded material is repeated.
In addition, when attaching an adhesive (tackifying agent) to a carbon fiber fabric, for example, the carbon fiber fabric is immersed in a resin (resin solution) or sol that makes up the adhesive, or By spraying resin (resin solution) or sol on the carbon fiber fabric, the adhesive is attached to the carbon fiber fabric, and the carbon fiber fabric with the adhesive still attached is mixed with the kneaded material in the manner described above. Charge into mold.

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 pouring forming methods, the carbon fiber fabric B is placed in the inner frame or formwork described above, and then the monolithic refractory (refractory raw material) is poured into the inner frame or formwork, followed by drying (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. Further, after drying (curing), reduction firing (caulking treatment) may be further performed to obtain a product brick (fired brick).
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.

Through the above steps, the graphite-containing refractory of the present invention in which the carbon fiber fabric is embedded inside the refractory body is obtained.
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 refractory lining for refining containers and transportation containers used in steel plants. In particular, it is suitable as a refractory lining for converters, which are used in very harsh environments, and among these, it is particularly suitable as tuyere bricks constituting the tuyere portion.

A graphite-containing refractory in which a carbon fiber fabric was embedded inside the refractory body was manufactured according to the procedure shown in FIG. 3. 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), a test piece (test piece size: 40 mm x 80 mm) was prepared by embedding a single layer or multiple layers of carbon fiber fabric inside the refractory body along its longitudinal direction. x 160 mm), the center-to-center distance was 100 mm, the load application acceleration was 0.5 mm/min, and the measurement was performed in accordance with the three-point bending test method described in JIS R2213.

Regarding the fracture energy, as shown in Figures 5-1 and 5-2, the position where the first peak value was shown in the load-displacement curve obtained in the 3-point bending strength test is used as the reference, and the fracture energy is measured at a displacement of 1 mm from the reference position. Evaluation was made based on the area of the range. Furthermore, Figure 5-1 shows an example of the fracture energy obtained from the load-displacement curve of the example of the present invention, and Figure 5-2 shows an example of the fracture energy obtained from the load-displacement curve of the comparative example in which no carbon fiber fabric is embedded inside. Each shows an example of destructive energy.
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 loss, an erosion index was determined, with the amount of erosion loss of Invention Formulation Example 1-3 in Table 1 taken as 100. As shown in FIG. 6(C), the test piece used was one in which a carbon fiber fabric was embedded perpendicularly to the surface (refractory operating surface) in contact with slag and molten steel. 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 40 x 80 x 200 mm sample was measured according to the ultrasonic pulse method specified in JIS R1605, and then heated at 1500°C for 10 minutes and water-cooled for 5 minutes. , the process of 10 minutes of atmospheric cooling as one cycle was repeated three times, and after the third cycle, the dynamic elastic modulus E ₃ was measured again using the above method, and the rate of change in the dynamic elastic modulus E ₃ /E ₀ before and after the test was calculated. It was evaluated as an indicator. As shown in FIG. 1, the test piece used was one in which a carbon fiber fabric was embedded along the longitudinal direction of the refractory body.

A refractory molded product using magnesia raw material as an aggregate, that is, a graphite-containing refractory without embedded carbon fiber fabric, was produced using the raw material composition shown in Table 1, and its erosion resistance and cracking resistance were evaluated. The results are also shown in Table 1.
As shown in Inventive Formulation Examples 1-1 to 1-7 in Table 1, when the graphite content is 1 to 80% by mass, the erosion resistance and cracking resistance are good, but the comparative formulation examples As shown in 1-1, when the graphite content is less than 1% by mass, the cracking resistance is significantly reduced. Furthermore, as shown in Comparative Formulation Example 1-2, when the graphite content exceeds 80% by mass, the erosion resistance is significantly reduced.
In addition, as shown in Invention Blend Examples 1-1 to 1-7, in the blend of magnesia/carbonaceous raw materials, the content of magnesia raw materials (magnesia concentration 100% by mass in the case of Table 1) is 20 to 99%. % by mass, the erosion resistance and cracking resistance are good. From the above, in order to achieve both erosion resistance and cracking resistance of graphite-containing refractories, the graphite content must be 1 to 80% by mass, and in the case of magnesia/carbonaceous raw materials, It can be seen that it is appropriate to set the content of the magnesia raw material to 20 to 99% by mass.

Tables 3 to 11 show the composition and properties (bending strength, fracture energy, erosion resistance, , cracking resistance).
First, the examples in Table 3 show the fiber diameter of the carbon fibers constituting the carbon fiber bundle, the number of carbon fibers per carbon fiber bundle, and the carbon fiber fabric buried inside the refractory body. We investigated the effects of the mass per 1 m ² of carbon fiber fabric and the density of carbon fibers in the cross section of the refractory parallel to the working surface of the refractory (buried density) on the bending strength, fracture energy, and cracking resistance of graphite-containing refractories. It is something that

In this example, the fiber diameter of the carbon fibers constituting the carbon fiber bundle is 0.5 to 50 μm, and the number of carbon fibers per carbon fiber bundle is 900 to ^350,000 . Carbon fiber fabrics with different masses were prepared, and these were embedded inside a magnesia-carbon refractory (refractory body) so that the density of carbon fibers in the refractory cross section parallel to the refractory working surface was different. The magnesia-carbon refractory used had the composition of Invention Blend Example 1-3 in Table 1. The number of buried layers of the carbon fiber fabric was one, and it was composed of one fabric. Further, a carbon fiber fabric was dipped in a phenol resin (resin solution) as an adhesive in advance, and the carbon fiber fabric to which the phenol resin (resin solution) was attached was embedded in the refractory body. The maximum particle size of the aggregate (magnesia) constituting the refractory body is less than 5 mm.
As shown in Invention Examples 2-1 to 2-7, the fiber diameter of the carbon fibers constituting the carbon fiber bundle is 1 to 45 μm, and the number of carbon fibers per carbon fiber bundle is 1,000 to 300,000. In this case, the mass of carbon fiber fabric per 1 m ² is 40 to 1,300 g, the density of carbon fibers in the cross section of the refractory parallel to the working surface of the refractory is 10 to 2,000 fibers/mm ² , and high bending strength and fracture energy. Cracking resistance has been achieved.

On the other hand, as shown in Comparative Example 2-1, when the fiber diameter of the carbon fibers constituting the carbon fiber bundle is less than 1 μm and the number (number) of carbon fibers per carbon fiber bundle is less than 1000, The mass of fiber fabric per ^1m2 is less than 40g, the density of carbon fibers in the cross section of the refractory parallel to the working surface of the refractory (embedded density) is less than 10 fibers/ ^mm2 , and the carbon fiber fabric is too thin, resulting in high bending. Strength, fracture energy, and cracking resistance cannot be obtained.
Furthermore, as shown in Comparative Example 2-2, when the fiber diameter of the carbon fibers constituting the carbon fiber bundle is more than 45 μm and the number of carbon fibers (number) per carbon fiber bundle is more than 300,000, carbon fiber fabric The mass per 1 ^m2 is over 1,300 g, the density of carbon fibers in the cross section of the refractory parallel to the working surface of the refractory is over 2,000 fibers/ ^mm2 , and the refractory raw material (magnesia carbon When molding the raw material), cracks occurred on the sides of the molded product, causing the carbon fiber fabric to protrude, making molding difficult. The reason for this is that the carbon fiber bundles that make up the carbon fiber fabric are too thick, resulting in a thick carbon fiber fabric and poor intertwining between the carbon fiber fabric and the refractory raw material, which tends to cause springback during molding. This can be mentioned. Furthermore, as shown in Comparative Example 2-3, it is not possible to form a carbon fiber fabric simply by orienting carbon fiber bundles in one direction, and therefore it is impossible to manufacture graphite-containing refractories with embedded carbon fiber fabrics. there were.

From the above, the mass of the carbon fiber fabric buried in the refractory body per 1 m ² is set at 40 to 1300 g, and the density of carbon fibers in the cross section of the refractory parallel to the working surface of the refractory is set at 10 to 2000 fibers/mm ² . It can be seen that by doing so, a graphite-containing refractory that is moldable and has high bending strength, fracture energy, and cracking resistance can be obtained. In addition, in order to make the mass of carbon fiber fabric 40 to 1300 g per 1 m ² , the fiber diameter of the carbon fibers constituting the carbon fiber bundle should be 1 to 45 μm, and the number of carbon fibers per carbon fiber bundle (number of carbon fibers) should be 1 to 45 μm. ) is preferably 1,000 to 300,000.

The examples in Table 4 show that the spacing between carbon fiber bundles constituting a carbon fiber fabric (the spacing between carbon fiber bundles woven in the same direction) affects the bending strength, fracture energy, and cracking resistance of graphite-containing refractories. This is a study of the impact.
In this example, carbon fiber bundles with a diameter of 7 μm and a number of carbon fibers (number) of 75,000 per bundle were woven in lengths of 1 m at intervals of 3 mm, 5 mm, 10 mm, 20 mm, and 30 mm, respectively. Prepare a carbon fiber fabric with a mass of 110 to 1120 g per ² , and use magnesia carbon material so that the density of carbon fibers in the cross section of the refractory parallel to the working surface of the refractory is 200 to 2000 fibers/mm ² . It was buried inside the refractory (refractory body). The magnesia-carbon refractory used had the composition of Invention Blend Example 1-3 in Table 1. The number of buried layers of the carbon fiber fabric was one, and it was composed of one fabric. A carbon fiber fabric was dipped in a phenol resin (resin solution) as an adhesive in advance, and the carbon fiber fabric to which the phenol resin (resin solution) was attached was embedded in the refractory body. The maximum particle size of the aggregate (magnesia) constituting the refractory body is less than 5 mm.

As shown in Invention Example 2-4 and Invention Examples 3-2 to 3-4, when the distance between the carbon fiber bundles constituting the carbon fiber fabric (weaving interval) is more than 3 mm, the carbon fiber fabric and the refractory It has good intertwining with the raw materials (magnesia/carbonaceous raw materials) and has high bending strength, fracture energy, and cracking resistance.
On the other hand, as shown in Invention Example 3-1, when the interval between the carbon fiber bundles constituting the carbon fiber fabric (weave interval) is set to 3 mm or less, the carbon fiber fabric and the refractory raw material are not entangled, and Invention Example 3 -2 to Invention Examples 3-4, the bending strength, fracture energy, and cracking resistance are lower.
From the above, if the spacing between the carbon fiber bundles that make up the carbon fiber fabric (weave spacing) is set to more than 3 mm, the carbon fiber fabric and the refractory material will be intertwined well, resulting in high bending strength, fracture energy, and cracking resistance. It has been found that a graphite-containing refractory having the following properties can be obtained.

In the example shown in Table 5, the influence of pre-treatment of carbon fiber fabric with an adhesive on the bending strength, fracture energy, and cracking resistance of graphite-containing refractories was investigated.
In this example, a carbon fiber fabric with a mass of 335 g per 1 m ² is made of carbon fiber bundles with a carbon fiber diameter of 7 μm and a carbon fiber number (number) of 75,000 per bundle, woven at intervals of 10 mm. The carbon fiber fabric is immersed in various adhesives (solutions), and the carbon fiber fabric to which the adhesive (solution) is attached has a density of 610 carbon fibers in the cross section of the refractory parallel to the working surface of the refractory. It was buried inside a magnesia-carbon refractory (refractory body) so that the refractory was refractory/mm ² . Furthermore, in some invention examples, carbon fiber fabrics were embedded inside magnesia-carbon refractories (refractory body) at the same density as above without adhering adhesive (solution). The magnesia-carbon refractory used had the composition of Invention Blend Example 1-3 in Table 1. The number of buried layers of the carbon fiber fabric was one, and it was composed of one fabric. The maximum particle size of the aggregate (magnesia) constituting the refractory body is less than 5 mm.

As shown in Invention Example 2-4 and Invention Examples 4-1 to 4-10, when a carbon fiber fabric to which an adhesive is attached is buried, the adhesion between the carbon fibers and the relationship between the carbon fiber fabric and the refractory raw material decrease. Since the adhesion of the carbon fiber fabric is improved, the bending strength and fracture energy/crack resistance are higher than when no adhesive is attached to the carbon fiber fabric as shown in Invention Example 4-11. In addition, as shown in Invention Examples 4-6 to 4-10, when carbon fiber fabrics with two types of adhesives are embedded, the adhesion is further improved, resulting in particularly high bending strength and fracture energy. Cracking resistance has been achieved.
From the above, it was found that graphite-containing refractories with high bending strength, fracture energy, and cracking resistance can be obtained by attaching adhesives such as phenolic resin to carbon fiber fabrics and embedding them in the refractory body. Ta.

In the example shown in Table 6, the influence of the number of fabrics per layer of carbon fiber fabric and the number of embedded layers of carbon fiber fabric on the bending strength, fracture energy, and cracking resistance of graphite-containing refractories was investigated.
In this example, carbon fiber bundles with a fiber diameter of 7 μm and 75,000 carbon fibers per bundle are woven at intervals of 10 mm. Carbon fibers with a mass of 335 to 1050 g per 1 m ² are used. A fiber fabric is used, and the density of carbon fibers in the cross section of the refractory parallel to the working surface of the refractory is 610 to 1900 fibers/ ^mm2 , and the number of fabrics per layer of carbon fiber fabric and the carbon fibers are The number of buried layers of the fabric was changed and the fabric was buried inside the magnesia-carbon refractory (refractory body). The magnesia-carbon refractory used had the composition of Invention Blend Example 1-3 in Table 1. A carbon fiber fabric was dipped in a phenol resin (resin solution) as an adhesive in advance, and the carbon fiber fabric to which the phenol resin (resin solution) was attached was embedded in the refractory body. The maximum particle size of the aggregate (magnesia) constituting the refractory body is less than 5 mm.

As shown in Invention Example 2-4 and Invention Examples 5-1 to 5-4, regardless of the number of fabrics per layer of carbon fiber fabric or the number of buried layers of carbon fiber fabric, high bending strength and fracture energy Cracking resistance has been achieved. However, as the number of fabrics per layer of carbon fiber fabric and the number of embedded layers of carbon fiber fabric increase, the bending strength, fracture energy, and cracking resistance increase, albeit slightly.
From the above, if the number of fabrics per layer of carbon fiber fabric is one or more and one or more layers of carbon fiber fabric are embedded, a graphite-containing refractory with high bending strength, fracture energy, and cracking resistance can be obtained. I found out that it can be done.

The examples in Table 7 show that when two or more layers of carbon fiber fabric are buried at intervals inside the refractory body, the interval between the layers of the carbon fiber fabric (embedment interval) is the shapeability of the graphite-containing refractory. This study investigated the effect on
In this example, carbon fiber bundles with a fiber diameter of 7 μm and 75,000 carbon fibers per bundle are woven at intervals of 10 mm. Carbon fibers with a mass of 44 to 513 g per 1 m ² Using fibrous fabrics, 3 or 5 layers of these carbon fiber woven fabrics are embedded inside a magnesia carbon refractory (refractory body) at intervals of 8 mm, 10 mm, 20 mm, and 30 mm, respectively, and cracks are removed in the press-formed product. We investigated whether this was occurring. The magnesia-carbon refractory used had the composition of Invention Blend Example 1-3 in Table 1. Each layer of the carbon fiber fabric was composed of one or three fabrics, and the density of carbon fibers in the cross section of the refractory parallel to the working surface of the refractory was 71 to 925 fibers/mm ² . A carbon fiber fabric was dipped in a phenol resin (resin solution) as an adhesive in advance, and the carbon fiber fabric to which the phenol resin (resin solution) was attached was embedded in the refractory body. The maximum particle size of the aggregate (magnesia) constituting the refractory body is less than 5 mm.

As shown in Invention Example 2-4, Invention Example 5-3, Invention Example 5-4, Invention Example 6-2, Invention Example 6-3, Invention Example 6-5 to Invention Example 6-8, multiple layers of carbon fiber When the buried spacing between the layers of fabric is 10 mm or more, the spacing between the carbon fiber fabrics in the press-forming direction is not too narrow, so the carbon fiber bundles constituting the carbon fiber fabric do not spring back during molding, and the molded product No cracks occurred.
On the other hand, as shown in Invention Example 6-1 and Invention Example 6-4, when the embedded spacing between layers of multiple layers of carbon fiber fabric is less than 10 mm, the spacing between the carbon fiber fabrics in the press forming direction is too narrow. During molding, the carbon fiber bundle caused springback, which caused cracks in the molded product.
From the above, when burying multiple layers of carbon fiber fabrics at intervals, in order to form a refractory without causing cracks, the burying distance between layers of carbon fiber fabrics should be 10 mm or more. I found this to be preferable.

A similar study was conducted on graphite-containing refractories whose aggregates are alumina raw materials, silicon carbide raw materials, and silica raw materials used for lining hot metal pretreatment vessels.
The examples in Table 8 are about alumina, silica, silicon carbide, and carbon refractories (graphite-containing refractories whose aggregates are alumina raw materials, silicon carbide raw materials, and silica raw materials) used for lining hot metal pretreatment vessels. This study investigated the effects of composition on the bending strength, fracture energy, cracking resistance, and erosion resistance of graphite-containing refractories.
In this example, a carbon fiber fabric with a mass of 335 g per 1 m ² is made of carbon fiber bundles with a carbon fiber diameter of 7 μm and a carbon fiber number (number) of 75,000 per bundle, woven at intervals of 10 mm. This is applied inside the alumina, silica, silicon carbide, and carbon refractories (refractory body) so that the density of carbon fibers in the cross section of the refractory parallel to the refractory operating surface is 610 fibers/ ^mm2 . Buried. The number of buried layers of the carbon fiber fabric was one, and it was composed of one fabric. A carbon fiber fabric was dipped in a phenol resin (resin solution) as an adhesive in advance, and the carbon fiber fabric to which the phenol resin (resin solution) was attached was embedded in the refractory body. The maximum particle size of the aggregate (alumina raw material, silicon carbide raw material, silica raw material) constituting the refractory body is less than 5 mm.

As shown in Invention Examples 7-1 to 7-7, the content of the alumina raw material was 10 to 95% by mass, the content of the silica raw material was 1 to 50% by mass, and the graphite content was 1 to 80% by mass. In this case, high bending strength, fracture energy, cracking resistance, and erosion resistance are obtained.
On the other hand, as shown in Comparative Example 7-1, when the content of alumina raw material is less than 10% by mass, the content of silica raw material is less than 1% by mass, and the graphite content is more than 80% by mass, destruction occurs. Both energy and erosion resistance are significantly reduced.
Furthermore, as shown in Comparative Example 7-2, when the content of alumina raw material is more than 95% by mass, the content of silica raw material is less than 1% by mass, and the content of graphite is less than 1% by mass, cracks due to thermal spalling occur. The occurrence of cracking cannot be suppressed, and fracture energy and cracking resistance are significantly reduced.
From the above, in alumina, silica, silicon carbide, and carbon refractories, the alumina raw material content is 10 to 95 mass%, the silica raw material content is 1 to 50 mass%, and the graphite content is 1 to 80 mass%. %, it can be seen that both high erosion resistance and high fracture energy/crack resistance can be achieved.

The examples in Table 9 are alumina, silica, silicon carbide, and carbon refractories (graphite-containing refractories using alumina raw materials, silicon carbide raw materials, and silica raw materials as aggregates) used for lining hot metal pretreatment vessels. , for 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 graphite. This study investigated the effects on the bending strength, fracture energy, cracking resistance, and erosion resistance of the contained refractories.
In this example, a carbon fiber fabric with a mass of 335 g per 1 m ² is made of carbon fiber bundles with a carbon fiber diameter of 7 μm and a carbon fiber number (number) of 75,000 per bundle, woven at intervals of 10 mm. This is applied inside the alumina, silica, silicon carbide, and carbon refractories (refractory body) so that the density of carbon fibers in the cross section of the refractory parallel to the refractory operating surface is 610 fibers/ ^mm2 . Buried. The number of buried layers of the carbon fiber fabric was one, and it was composed of one fabric. A carbon fiber fabric was dipped in a phenol resin (resin solution) as an adhesive in advance, and the carbon fiber fabric to which the phenol resin (resin solution) was attached was embedded in the refractory body. The maximum particle size of the aggregate (alumina raw material, silicon carbide raw material, silica raw material, refractory waste obtained by crushing used alumina, silica, silicon carbide, carbonaceous refractory) that makes up the refractory body is less than 5 mm.

As shown in Invention Examples 8-1 to 8-3, the content of refractory waste was 10 to 90% by mass, the content of silica raw material was 1% by mass or more, and the graphite content was 1 to 80% by mass. In this case, fracture energy, cracking resistance, and erosion resistance comparable to those of graphite-containing refractories using only virgin raw materials shown in Table 8 were obtained.
On the other hand, as shown in Comparative Example 8-1, when the refractory waste content is more than 90% by mass, the silica raw material content is less than 1% by mass, and the graphite content is less than 1% by mass, the fracture energy Cracking resistance and erosion resistance are significantly reduced.
From the above, for alumina, silica, silicon carbide, and carbon refractories, refractory waste obtained by crushing used alumina, silica, silicon carbide, and carbon refractories as part of the aggregate raw material is Regarding the graphite-containing refractory used, if the content of refractory waste is 10 to 90% by mass, the content of silica raw material is 1% by mass or more, and the graphite content is 1 to 80% by mass, the fracture energy and resistance are It can be seen that the crackability can be maintained at a high level, and furthermore, it has the same level of erosion resistance as a graphite-containing refractory using only virgin raw materials.

The examples in Table 10 show the bending strength, fracture energy, and The effect on cracking resistance and erosion resistance was investigated.
In this example, a carbon fiber fabric with a mass of 335 g per 1 m ² is made of carbon fiber bundles with a carbon fiber diameter of 7 μm and a carbon fiber number (number) of 75,000 per bundle, woven at intervals of 10 mm. This was buried inside the alumina/silicon carbide/carbon refractory (refractory body) so that the density of carbon fibers in the cross section of the refractory parallel to the operating surface of the refractory was 610 fibers/ ^mm2 . . The number of buried layers of the carbon fiber fabric was one, and it was composed of one fabric. A carbon fiber fabric was dipped in a phenol resin (resin solution) as an adhesive in advance, and the carbon fiber fabric to which the phenol resin (resin solution) was attached was embedded in the refractory body. The maximum particle size of the aggregate (alumina raw material, silicon carbide raw material) constituting the refractory body is less than 5 mm.

As shown in Invention Examples 9-1 to 9-3, when the alumina raw material content is 10 to 95% by mass and the graphite content is 1 to 80% by mass, high bending strength, fracture energy, and cracking resistance are achieved. and corrosion resistance.
On the other hand, as Comparative Example 9-1 shows, when the alumina raw material content is less than 10% by mass and the graphite content is more than 80% by mass, the fracture energy and erosion resistance are significantly reduced. Further, as shown in Comparative Example 9-2, 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 significantly reduced.
From the above, in alumina/silicon carbide/carbon refractories, if the alumina raw material content is 10 to 95% by mass and the graphite content is 1 to 80% by mass, high fracture energy, cracking resistance, and melting resistance are achieved. It can be seen that damage loss can be obtained.

The examples in Table 11 show that the composition of silica/silicon carbide/carbon refractories (graphite-containing refractories using silica raw materials and silicon carbide raw materials as aggregates) is the bending strength, fracture energy, and resistance of the graphite-containing refractories. The effect on cracking resistance and erosion resistance was investigated.
In this example, a carbon fiber fabric with a mass of 335 g per 1 m ² is made of carbon fiber bundles with a carbon fiber diameter of 7 μm and a carbon fiber number (number) of 75,000 per bundle, woven at intervals of 10 mm. This was buried inside the silica/silicon carbide/carbon refractory (refractory body) so that the density of carbon fibers in the cross section of the refractory parallel to the refractory operating surface was 610 fibers/ ^mm2 . . The number of buried layers of the carbon fiber fabric was one, and it was composed of one fabric. A carbon fiber fabric was dipped in a phenol resin (resin solution) as an adhesive in advance, and the carbon fiber fabric to which the phenol resin (resin solution) was attached was embedded in the refractory body. The maximum particle size of the aggregate (silica raw material, silicon carbide raw material) constituting the refractory body is less than 5 mm.

As shown in Invention Example 10-1 and Invention Example 10-2, when the silica raw material content is 1 to 50% by mass and the graphite content is 1 to 80% by mass, high bending strength and fracture energy/crack resistance are achieved. and corrosion resistance.
On the other hand, as shown in Comparative Example 10-1, when the silica raw material content is less than 1% by mass and the graphite content is more than 80% by mass, the fracture energy and cracking resistance are reduced. Furthermore, as shown in Comparative Example 10-2, the fracture energy and cracking resistance are also reduced when the graphite content exceeds 80% by mass.
From the above, in silica/silicon carbide/carbon refractories, if the silica raw material content is 1 to 50% by mass and the graphite content is 1 to 80% by mass, high bending strength, fracture energy, and cracking resistance can be achieved. It can be seen that good properties and corrosion resistance can be obtained.

A Refractory body
B Carbon fiber fabric
b Carbon fiber bundle
x Refractory working surface
y Anti-movement surface

Claims (13)

A graphite-containing refractory in which a carbon fiber fabric (B) is embedded inside a refractory body (A) having a graphite content of 1 to 80% by mass,
The carbon fiber fabric (B) is a graphite-containing refractory characterized by a mass of 40 to 1,300 g per 1 m ² . The carbon fiber fabric (B) is a fabric in which carbon fiber bundles (b) are woven in two or more directions at intervals exceeding the maximum particle size of the aggregate constituting the refractory body (A),
The carbon fiber bundle (b) is a bundle of carbon fibers with a fiber diameter of 1 to 45 μm, and the number of carbon fibers per bundle is 1000 to 300000,
The graphite-containing refractory according to claim 1, characterized in that the density of the carbon fibers constituting the carbon fiber fabric (B) in the cross section of the refractory parallel to the working surface of the refractory is 10 to 2000 fibers/mm ² . thing. The graphite-containing refractory according to claim 1, characterized in that a carbon fiber fabric (B) is embedded inside the refractory body (A) along a direction perpendicular to the refractory operating surface. The graphite-containing refractory according to any one of claims 1 to 3, wherein the carbon fiber fabric (B) has carbon fiber bundles (b) woven in the same direction at intervals of more than 3 mm. The graphite-containing refractory according to any one of claims 1 to 3, wherein the carbon fiber fabric (B) is composed of one fabric or two or more laminated fabrics. The graphite-containing refractory according to any one of claims 1 to 3, characterized in that one layer or two or more layers of carbon fiber fabric (B) are embedded inside the refractory main body (A). . The graphite-containing refractory according to claim 6, characterized in that the interval between two or more layers of carbon fiber fabric (B) embedded within the refractory body (A) is 10 mm or more. The carbon fiber fabric (B) adheres to the refractory body (A) through an adhesive component, and the adhesive component includes organic resin, inorganic fine particles derived from inorganic sol, organic matter derived from tar and/or pitch, The graphite-containing refractory according to any one of claims 1 to 3, characterized in that the graphite-containing refractory is one or more selected from organic substances derived from organic glue. The graphite-containing refractory according to any one of claims 1 to 3, wherein the refractory body (A) contains 20 to 99% by mass of a magnesia raw material having a magnesia concentration of 90% by mass or more. The graphite-containing refractory according to claim 1, wherein the refractory body (A) contains 10 to 95% by mass of an alumina raw material having an alumina concentration of 70% by mass or more. The graphite-containing refractory according to claim 1, wherein the refractory body (A) contains 1 to 50% by mass of silica raw material. The graphite-containing refractory according to claim 10 or 11, wherein the refractory body (A) contains 1% by mass or more of a silicon carbide raw material having a silicon carbide concentration of 80% by mass or more. The graphite-containing refractory according to any one of claims 1 to 3, wherein the refractory body (A) contains 10 to 90% by mass of refractory waste obtained by crushing used refractories.

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