Structure and method for manufacturing same, and segment and method for manufacturing same

Abstract

This structure 1 comprises: a body 3 in which a plurality of segments 2, each of which is a sintered body of ceramics, are combined; and a surface layer 4 made of ceramics covering at least a part of a surface of the body 3.

Description

Structure and manufacturing method thereof, and segment and manufacturing method thereof

[0001] The present disclosure relates to a ceramic structure and a manufacturing method thereof, as well as to a segment constituting the ceramic structure and a manufacturing method thereof.

[0002] Ceramics have higher heat resistance than metals and lower reactivity with other materials they come into contact with, so they are expected to be used in high-purity reaction vessels and other applications in high-temperature environments.

[0003] Japanese Patent Application Laid-Open No. 2007-238366

[0004] However, to manufacture ceramic structures, it is necessary to sinter green bodies, but large green bodies are difficult to handle and the shaping process is unstable, resulting in poor yield. In addition, there are no furnaces capable of sintering large green bodies, and even if a new large furnace were to be built, it would require a large amount of construction costs, and it would require a great deal of energy to heat the inside of a large furnace to a high temperature.

[0005] Patent Document 1 discloses a hollow ceramic structure in which a plurality of units having a three-dimensional complex shape with a hollow structure are combined and joined together to form an integrated structure, thereby forming an overall component shape having an internal cavity. However, the hollow ceramic structure disclosed in Patent Document 1 has a problem in that it is unable to ensure sufficient shape retention and sealing properties.

[0006] The present disclosure has been made in view of the above problems, and its object is to provide a ceramic structure having excellent properties such as strength and sealing ability.

[0007] In order to solve the above problems, a structure according to one aspect of the present disclosure comprises a main body formed by combining a plurality of segments of a ceramic sintered body, and a ceramic surface layer covering at least a portion of the surface of the main body.

[0008] Another aspect of the present disclosure is a method for manufacturing a structure, which includes a step of forming a surface layer covering at least a portion of the surface of a body including a plurality of segments of a ceramic sintered body by thermal spraying a ceramic onto at least a portion of the surface of the body.

[0009] Yet another aspect of the present disclosure is a segment, which is a segment of a ceramic sintered body that constitutes a ceramic structure and has a fitting portion that fits with another segment.

[0010] Yet another aspect of the present disclosure is a method for manufacturing a segment, the method comprising molding a segment having a mating portion that mates with another segment, and sintering the molded segment.

[0011] According to the present disclosure, it is possible to provide a ceramic structure having excellent properties such as strength and sealing ability.

[0012] 2(a) and 2(b) are examples of perspective views of a structure according to an embodiment. FIG. 2(a) is a top view of a segment, and FIG. 2(b) is a side view of the segment. FIG. 3(a) is a side view of a main body, and FIG. 3(b) is a top view of the main body. FIG. 4(a) is a side view of the structure, and FIG. 4(b) is a top view of the structure. FIG. 4(b) is a flowchart showing the steps of a method for manufacturing a structure according to an embodiment.

[0013] FIG. 1 is an example of a perspective view of a structure according to an embodiment. The structure 1 includes a main body 3 formed by combining a plurality of segments 2 of a ceramic sintered body, and a surface layer 4 covering at least a portion of the surface of the main body 3. The surface layer 4 includes a thermally sprayed ceramic film. The surface layer 4 is formed, for example, by thermally spraying ceramic onto the surface of the main body 3. In the structure 1 shown in FIG. 1, the surface layer 4 is formed only on the outer surface (external surface) of the main body 3. However, if the main body 3 has a hollow shape, the surface layer 4 may also be formed on the inner surface (internal surface) of the main body 3. In other words, the surface layer 4 may be formed so as to cover part or all of one or both of the outer and inner surfaces of the main body 3. The surface includes the top surface, side surface, bottom surface, etc.

[0014] A large ceramic structure can be realized by combining multiple ceramic sintered bodies to form the main body 3. Furthermore, by covering the surface of the main body 3 with a ceramic sprayed film, the multiple segments 2 can be firmly fixed together, improving the strength of the structure 1 and ensuring sufficient shape retention. Furthermore, by covering the gaps between the segments 2 with a ceramic sprayed film, the sealing properties of the structure 1 can be improved.

[0015] 2(a) and 2(b) are schematic diagrams showing an example of the structure of the segment 2. FIG. 2(a) is a top view of the segment 2, and FIG. 2(b) is a side view of the segment 2. The segment 2 is formed by injection molding, casting, or the like using ceramics such as alumina, and then sintered. Even when manufacturing a large structure 1, the size of each segment 2 can be kept small, allowing the segments 2 to be fired using an existing furnace. This also improves the accuracy of the shape of each segment 2. This also improves the yield when manufacturing the segments 2.

[0016] Each segment 2 has fitting portions 5 that fit with adjacent segments 2 on the left and right and above and below when multiple segments 2 are combined to form the main body 3. This allows the process of combining multiple segments 2 to form the main body 3 to be carried out quickly and easily. It also improves the accuracy and stability of the shape of the structure 1, and prevents the shape of the main body 3 from collapsing when ceramics are sprayed onto the surface of the main body 3 to form the surface layer 4. Furthermore, because the segments 2 can be firmly combined with each other, it is possible to improve the strength and shape retention of the main body 3.

[0017] The segments 2 have ceramic particles 6 on their surfaces, which improves the adhesion between the segments 2 and the surface layer 4, thereby improving the strength, shape retention, sealing properties, etc. of the structure 1.

[0018] 3(a) and 3(b) are schematic diagrams showing the structure of the main body 3 of the structure 1 according to the embodiment. FIG. 3(a) is a side view of the main body 3, and FIG. 3(b) is a top view of the main body 3. The main body 3 of this embodiment has a cylindrical shape formed by stacking a plurality of segments 2 in an annular shape. The structure can also be made isotropic by changing the segment shape and assembly method.

[0019] 4(a) and (b) schematically show the structure of a structure 1 according to an embodiment. Fig. 4(a) is a side view of the structure 1, and Fig. 4(b) is a top view of the structure 1. The structure 1 includes a main body 3 and a surface layer 4 provided on the outer surface of the main body 3 via an adhesive layer 7.

[0020] In the structure 1 of this embodiment, the segment 2 may contain any ceramic such as alumina, zirconia, zinc oxide, aluminum titanate, barium titanate, silicon nitride, boron nitride, silicon carbide, or a mixture thereof.

[0021] The segment 2 may be formed by any known method such as slip casting, injection molding, etc. The formed body of the segment 2 may be sintered at a temperature depending on the type of ceramic.

[0022] The segments 2 may be manufactured by molding and sintering ceramic powder. The segments 2 may also be manufactured by sintering a molded body containing ceramic powder and ceramic fibers. That is, the segments 2 may include a sintered body of ceramic powder and a sintered body of ceramic fibers. This can improve the strength of each segment 2, and therefore the strength of the structure 1.

[0023] The segment 2 may have ceramic particles 6 on its surface. This can improve the adhesion between the main body 3 and the surface layer 4. The particles 6 may include any ceramic, such as alumina, zirconia, zinc oxide, aluminum titanate, barium titanate, silicon nitride, boron nitride, silicon carbide, or a mixture thereof. The particles 6 may be formed by applying a paste containing the particles 6 to the surface of the molded body of the segment 2 and then sintering the paste. The particles 6 may include the same type of ceramic as the segment 2.

[0024] The main body 3 may have any shape, such as a cylinder, a prism, a cone, a pyramid, etc. The segment 2 or the main body 3 may be shaped by a three-dimensional printer or the like.

[0025] The surface layer 4 may comprise any material such as alumina, zirconia, zinc oxide, aluminum titanate, barium titanate, silicon nitride, boron nitride, silicon carbide, or mixtures thereof.

[0026] The segments 2 and the surface layer 4 may contain the same type of ceramic. In this case, the main body 3 and the surface layer 4 can have similar properties such as thermal expansion coefficients, thereby improving the properties of the structure 1, such as thermal shock resistance. The segments 2 and the surface layer 4 may contain alumina. The alumina content in the segments 2 and the surface layer 4 may be 90% or more.

[0027] The surface layer 4 may be formed by ceramic spraying. The surface layer 4 may be formed by ceramic plasma spraying, particularly water plasma spraying. Plasma spraying is a technique for forming a film by using a high-temperature, high-velocity plasma jet as a heat source to melt raw material particles and spray them onto a workpiece. In particular, water plasma spraying, which uses vaporized cooling water from a plasma torch as the working gas, is less expensive than other working gases. In addition, the plasma has a very large enthalpy and a high flame temperature (approximately 30,000°C), making it easy to form a film even on ceramic materials with high melting points. Furthermore, since thick deposition is possible, a large structure 1 can be manufactured and the strength of the structure 1 can be improved.

[0028] An adhesive layer 7 may be provided between the main body 3 and the surface layer 4. This can improve the adhesion between the main body 3 and the surface layer 4. The adhesive layer 7 may contain silicon. The adhesive layer 7 may be formed by applying a liquid containing a silicon compound such as silicon oxide to the outer surface of the segment 2 or the main body 3, and then performing a heat treatment.

[0029] The maximum length in the longitudinal direction of the structure 1 of this embodiment may be 1 m or more, 2 m or more, 3 m or more, 4 m or more, 5 m or more, 6 m or more, 7 m or more, 8 m or more, 9 m or more, or 10 m or more. The maximum length in the longitudinal direction of the structure 1 may be longer than the maximum side of a sintered body that can be sintered in an existing sintering furnace.

[0030] The structure 1 of this embodiment has excellent heat resistance, thermal shock resistance, and sealing properties, and can therefore be suitably used in rotary kilns for firing high-purity oxides used in firing lithium-ion battery materials, etc.

[0031] 5 is a flowchart showing the steps of a method for manufacturing a structure according to an embodiment. A plurality of segments 2 are molded (S10). When molding the segments 2 by slip casting, a slurry containing ceramic powder and ceramic fibers is prepared, poured into a water-absorbent mold, solidified, demolded, and dried. When molding the segments 2 by injection molding, a compound kneaded with ceramic and a binder is heated and injected into a mold, and then cooled and solidified. Ceramic fibers may be mixed into the compound.

[0032] A suspension containing a silicon compound is applied to the outer surface of the compact of segment 2 (S12), and the compact of segment 2 is fired (S14). A paste containing ceramic particles 6 is applied to the outer surface of the sintered compact of segment 2, and heat treatment is performed (S16). This produces a sintered compact of segment 2 having an adhesive layer 7 and ceramic particles 6 on its outer surface.

[0033] A plurality of segments 2 are assembled three-dimensionally to form the main body 3 (S18). A surface layer 4 is formed by forming a ceramic sprayed film on the outer surface of the main body 3 by water plasma spraying (S20).

[0034] The present disclosure has been described above based on examples. These examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of the components and processing steps, and that such modifications are also within the scope of the present disclosure.

[0035] The present disclosure is applicable to a ceramic structure and a manufacturing method thereof, as well as to a segment constituting a ceramic structure and a manufacturing method thereof.

[0036] 1 Structure, 2 Segment, 3 Body, 4 Surface layer, 5 Interlocking portion, 6 Particles, 7 Adhesive layer

Claims

1. A structure comprising a main body formed by combining a plurality of segments of a ceramic sintered body, and a ceramic surface layer covering at least a portion of the surface of the main body.

2. The structure according to claim 1, wherein the surface layer includes a thermally sprayed ceramic film.

3. The structure according to claim 1 or 2, further comprising an adhesive layer between the main body and the surface layer for adhering the main body and the surface layer.

4. The structure of claim 3, wherein the adhesion layer comprises silicon.

5. The structure according to claim 1 or 2, wherein the body and the surface layer contain alumina.

6. The structure according to claim 5, wherein the alumina content in the main body and the surface layer is 90% or more.

7. The structure according to claim 1 or 2, wherein the segments have mating portions that mate with adjacent segments.

8. A method for manufacturing a structure, comprising a step of forming a surface layer covering at least a portion of the surface of a body formed by combining a plurality of segments of ceramic sintered bodies by thermally spraying ceramic onto at least a portion of the surface of the body.

9. The method of claim 8, wherein the segments are formed by ceramic injection molding.

10. The method of claim 8, wherein the segments are formed by ceramic slip casting.

11. A method according to any one of claims 8 to 10, further comprising the step of providing ceramic particles on the surface of the segment before forming the surface layer.

12. A method according to any one of claims 8 to 10, comprising the step of applying a liquid containing a silicon compound to the surface of the segment or the body before forming the surface layer.

13. A segment of a ceramic sintered body that constitutes a ceramic structure, the segment having a fitting portion that fits with another segment.

14. The segment according to claim 13, having ceramic particles on the surface.

15. The segment according to claim 13 or 14, comprising a sintered body of ceramic powder and a sintered body of ceramic fibers.

16. A method for manufacturing a segment, comprising the steps of: molding a segment having a mating portion that mates with another segment; and sintering the molded segment.

17. The method of claim 16, wherein the step of forming the segments includes casting a slurry containing ceramics.

18. The method of claim 17, wherein the slurry comprises ceramic powder and ceramic fibers.

19. The method of claim 16, wherein the step of molding the segments includes injection molding a compound including ceramics and a binder.

20. A method according to any one of claims 16 to 19, comprising the step of applying a liquid containing a silicon compound to the surface of the formed segment before sintering the segment.

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