Method for forming ceramic matrix composite material

Abstract

To suitably mold a ceramic base composite material while suppressing the occurrence of molding defects.SOLUTION: A ceramic base composite material molding method for molding a ceramic base composite material by laminating sheets obtained by impregnating a reinforcing fiber with ceramic powder-comprising slurry and curing them, and then sintering them, executes the steps of: forming a laminated body by laminating the sheets in a lamination direction; and molding a cured body by covering the laminated body with a vacuum bag, and evacuating the inside of the vacuum bag. In the step of molding the cured body, with respect to the laminated body, a slurry removal material for absorbing the surplus slurry is arranged, and a deaeration circuit member provided at least at either side of the laminated body and exhausting bubbles generated inside the laminated body is arranged.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to methods for forming ceramic matrix composites. [Background technology]

[0002] Conventionally, a method for manufacturing a ceramic-based composite material member has been known in which a slurry-impregnated sheet, in which reinforcing fibers are impregnated with a slurry containing ceramic powder, is pressed using a mold to apply pressure to the sheet (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-081340 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the manufacturing method of Patent Document 1, when forming a thin ceramic-based composite material, the quality can be ensured, but when forming a thick ceramic-based composite material, it is difficult to ensure the quality. Specifically, when forming a thick ceramic-based composite material, the mold becomes long and large to suppress deformation of the mold, and the thickness of the composite material is large, so that degassing inside is insufficient and voids are formed, which makes it easy for molding defects to occur. In particular, since the slurry contains moisture, when a sheet in which the slurry is impregnated into the reinforcing fibers is vacuumed, the moisture becomes air bubbles, so that air bubbles are more likely to occur than in a resin-impregnated sheet in which the resin is impregnated into the reinforcing fibers.

[0005] Therefore, an object of the present disclosure is to provide a method for forming a ceramic-based composite material that can suitably form a ceramic-based composite material while suppressing the occurrence of forming defects. [Means for solving the problem]

[0006] The method for forming a ceramic matrix composite material disclosed herein is a method for forming a ceramic matrix composite material by stacking sheets in which reinforcing fibers are impregnated with a slurry containing ceramic powder, hardening the sheets, and then sintering the sheets to form a ceramic matrix composite material, and includes the steps of stacking the sheets in a stacking direction to form a laminate, and covering the laminate with a vacuum bag and drawing a vacuum inside the vacuum bag to form a hardened body.In the step of forming the hardened body, a slurry removal material for absorbing excess slurry is placed on the laminate, and a deaeration circuit member is placed on at least one side of the laminate to expel air bubbles generated inside the laminate. Effect of the Invention

[0007] According to the present disclosure, it is possible to suitably mold a ceramic matrix composite while suppressing the occurrence of molding defects. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing a method for forming a ceramic-based composite material according to the first embodiment. [Diagram 2] FIG. 2 is an explanatory view showing another example of the method for forming the ceramic-based composite material according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing a laminated structure. [Figure 4] FIG. 4 is a cross-sectional view showing a laminated structure in a molding method for a ceramic-based composite material according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments. In addition, the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially the same. Furthermore, the components described below can be appropriately combined, and when there are multiple embodiments, the respective embodiments can be combined.

[0010] [Embodiment 1] Fig. 1 is an explanatory view showing a method for forming a ceramic-based composite material according to embodiment 1. Fig. 2 is an explanatory view showing another example of a method for forming a ceramic-based composite material according to embodiment 1. Fig. 3 is a cross-sectional view showing a layered structure.

[0011] The method for forming a ceramic matrix composite according to the first embodiment is a method for forming a ceramic matrix composite by stacking sheets in which a slurry containing ceramic powder is impregnated into reinforcing fibers, drying and curing the sheets, and then firing the sheets. An example of the ceramic matrix composite is an oxide-based CMC (Ceramic Matrix Composites). The ceramic matrix composite is not particularly limited to an oxide-based CMC, and may be any ceramic matrix composite that can be formed by the forming method of the present embodiment.

[0012] (Method of forming ceramic-based composite materials) In the method for forming a ceramic-based composite material, as shown in FIG. 1, first, step S1 is performed to prepare a slurry 4 in which a ceramic powder 2 serving as a solute is dispersed in a solvent. In the forming method of the first embodiment, an oxide-based ceramic powder is used as the ceramic powder 2, specifically, an alumina powder is used. In addition, in the forming method of the first embodiment, water is used as the solvent. In step S1, the ceramic powder 2 and water are put into a stirring device 3 and mixed to prepare a slurry. Note that there is no particular limitation on the material as long as the slurry contains a solute and a solvent capable of forming an oxide-based CMC.

[0013] Next, in the method for forming a ceramic-based composite material, step S2 is performed in which the reinforcing fiber sheet 1 is immersed in the impregnation tank 5 that contains the slurry prepared in step S1. In step S2, the reinforcing fiber sheet 1 is impregnated with the slurry 4 in the impregnation tank 5 to form a prepreg 6 (sheet) that will become a slurry-impregnated sheet (step S3).

[0014] Next, in the method for forming a ceramic-based composite material, step S4 is performed in which the prepregs 6 are stacked in the stacking direction to form the laminate 10. In step S4, the laminate 10 is formed by simply stacking the prepregs 6 or by pressing the stacked prepregs 6 with a plate or vacuum pressure or the like.

[0015] In the method for forming a ceramic-based composite material, step S5 is performed in which the laminate 10 is covered with a vacuum bag, the inside of the vacuum bag is evacuated, and a hardened body is formed. In step S5, as shown in Fig. 1, the laminate 10 is not heated by a heater, and as shown in Fig. 2, the laminate 10 is heated by a heater. In the configuration shown in Fig. 1, the laminate 10 may be heated from the outside using an oven or the like. Here, the laminate structure in step S5 in the case where the laminate 10 is heated by a heater will be described with reference to Fig. 3.

[0016] As shown in FIG. 3, in step S5, first, a mold 11 is prepared as a base on which the laminate 10 is placed. The mold 11 is made of, for example, a metal material such as aluminum or iron. A composite material may be used for the mold 11. A breather 12 is disposed on the upper surface of the mold 11 as a heat insulating material. The breather 12 suppresses heat transfer to the mold 11. A heater mat 13 is disposed on the upper surface of the breather 12. The heater mat 13 is a heat source for heating the laminate 10. A shaping member 16 is provided on the upper surface of the heater mat 13 to shape the laminate 10 (cured body after curing) into a desired shape. The shaping member 16 is formed of, for example, a carbon fiber composite material, and is a member for shaping the cured body into a predetermined shape.

[0017] The laminate 10 is placed on the upper surface of the shaping member 16 via a peel ply 17a. The peel ply 17a on the lower side of the laminate 10 is a layer for peeling the laminate 10 from the shaping member 16 after curing. The peel ply 17a also has a function of absorbing excess slurry 4 contained in the laminate 10 and a function as a degassing circuit during evacuation. In addition, a dam member 18 is arranged on the upper surface of the heater mat 13 surrounding the laminate 10 to suppress the outflow of the prepreg 6 from the laminate 10.

[0018] A slurry removing material 20 is provided on the upper surface of the laminate 10 via a peel ply 17b. The peel ply 17b on the upper side of the laminate 10 is a layer for peeling off the laminate 10 from the slurry removing material 20 after hardening. The peel ply 17b also functions as a degassing circuit during evacuation. The slurry removing material 20 is, for example, a laminate of multiple glass cloths, and absorbs the excess slurry 4 contained in the laminate 10. The slurry removing material 20 also functions as a degassing circuit member that becomes a flow path for degassing the laminate 10 during evacuation. The slurry removing material 20 as a degassing circuit member discharges air bubbles generated inside the laminate 10.

[0019] A pressure plate 21 (pressure plate) for pressing the laminate 10 is provided on the upper surface of the slurry remover 20. The pressure plate 21 is formed, for example, using a carbon fiber composite material or a metal material, and has a flat plate shape. Although the pressure plate 21 has a flat plate shape, the shape is not particularly limited and may be any shape suitable for forming the laminate 10. Although the pressure plate 21 has a simple flat plate shape (without through holes), through holes may be formed in the plate thickness direction. In this case, the pressure plate 21 can discharge air bubbles generated inside the laminate 10 through the through holes of the pressure plate 21 during evacuation.

[0020] A breather 22 is disposed on the upper surface of the pressure plate 21. The breather 22 functions as a member for discharging the atmosphere inside the vacuum bag 23 that covers the laminate 10 during evacuation. The breather 22 also functions as a degassing circuit member for discharging air bubbles generated inside the laminate 10. When a through hole is formed in the pressure plate 21, degassing can also be performed from the upper surface of the laminate 10, facilitating degassing.

[0021] The upper surface of breather 22 is covered with vacuum bag 23. A sealing member 25 is provided between vacuum bag 23 and mold 11. Therefore, the inside of vacuum bag 24 is airtightly sealed. Vacuum bag 23 is provided with a suction port (not shown).

[0022] In the laminated structure described above, when a vacuum is drawn through the suction port, the laminated body 10 is pressed by atmospheric pressure through the pressure plate 21, and the laminated body 10 is heated by the heater mat 13. As a result, in step S5, the laminated body 10 is pressed and heated, whereby the laminated body 10 is dried and hardened, and becomes a hardened body.

[0023] In step S5, when the laminate 10 is heated, heating is performed from one side of the laminate 10 in the stacking direction by the heater mat 13, and degassing is performed from the other side of the stacking direction via the slurry remover 20. That is, in step S5, heating and hardening are performed from the part of the laminate 10 closer to the heat source, and degassing is performed from the part of the laminate 10 farthest from the heat source.

[0024] Then, in the method for forming a ceramic-based composite material, step S6 is performed in which the hardened body formed in step S5 is fired in a firing furnace such as an electric furnace. By performing step S6, the hardened body is fired to form a formed ceramic-based composite material.

[0025] In step S4 of the first embodiment, the prepreg 6 is laminated, but the slurry 4 may be applied to the surface of the prepreg 6 after lamination of the prepreg 6. In this way, even if the slurry 4 is insufficient on the surface of the prepreg 6 and voids are formed, the gaps can be filled with the slurry 4 by applying the slurry 4, and thus the loss of the slurry 4 can be suppressed.

[0026] In step S4 of the first embodiment, after lamination of the prepreg 6, the prepreg 6 may be covered with a vacuum bag and the inside of the vacuum bag may be evacuated. As a result, even if the prepreg 6 entraps air during lamination, the air can be removed by evacuating, so that the formation of voids can be suppressed. In step S4, the air may be removed and the excess slurry 4 may be removed by evacuating. In this case, since the excess slurry 4 is removed in advance, a gas-permeable film such as a perforated release film may be disposed between the laminate 10 and the peel ply 17b. At this time, the slurry removing material 20 functions as a degassing circuit member. The gas-permeable film provided between the laminate 10 and the slurry removing material 20 may be disposed in step S5 of the first embodiment.

[0027] Furthermore, in step S6 of the first embodiment, pressure may be applied to the hardened body. In this case, in step S6, the pressure applied to the hardened body during firing may be greater than the pressure applied to the laminate 10 during molding in step S5, so that the pressure applied to the hardened body during firing is greater. This allows the pressure applied to the hardened body during firing to be greater, so that cracks can be suppressed even if the hardened body has residual strain. Note that the pressure applied in step S6 is more effective in the second embodiment described below.

[0028] In the first embodiment, the slurry removing material 20 serving as a degassing circuit member is disposed above the laminate 10, but a degassing circuit member may also be provided below the laminate 10.

[0029] In addition, in the first embodiment, the slurry removing material 20 serving as a deaeration circuit member is disposed above the laminate 10, and the heater mat 13 is disposed below the laminate 10, but the arrangement of the slurry removing material 20 and the heater mat 13 may be reversed.

[0030] [Embodiment 2] Next, a second embodiment will be described with reference to Fig. 4. In the second embodiment, in order to avoid repetitive description, only the parts different from the first embodiment will be described, and the parts having the same configuration as the first embodiment will be described with the same reference numerals. Fig. 4 is a cross-sectional view showing a laminated structure in a molding method of a ceramic-based composite material according to the second embodiment.

[0031] In the second embodiment, in step S5, the pressed area pressed by the pressure plate 21 is larger than the pressing area where the pressure plate 21 presses the laminate 10. The pressed area is the upper surface of the pressure plate 21, and is the area of ​​the surface to which the atmospheric pressure P1 is applied. The pressing area is the lower surface of the pressure plate 21, and is the area of ​​the surface to which the pressure plate 21 applies the pressure P2 to the laminate 10. Specifically, the pressure plate 21 has a shape in which a flange portion is formed on the upper side of the main body portion that presses the laminate 10. Since the pressing area is smaller than the pressed area, the pressure P2 applied to the pressing area is larger than the pressure P1 applied to the pressed area.

[0032] As described above, the method for forming the ceramic-based composite material according to the embodiment can be understood, for example, as follows.

[0033] The method for forming a ceramic-based composite material according to the first aspect is a method for forming a ceramic-based composite material by stacking sheets (prepregs 6) in which reinforcing fibers (reinforcing fiber sheets 1) are impregnated with a slurry 4 containing ceramic powder 2, curing the sheets, and sintering the sheets to form a ceramic-based composite material. The method includes a step S4 of stacking the sheets in the stacking direction to form a laminate 10, and a step S5 of covering the laminate 10 with a vacuum bag 23 and evacuating the inside of the vacuum bag 23 to form a hardened body. In the step S5 of forming the hardened body, a slurry removal material 20 for absorbing excess slurry 4 is disposed on the laminate 10, and a deaeration circuit member (slurry removal material 20) is disposed on at least one side of the laminate 10 to expel air bubbles generated inside the laminate 10.

[0034] According to this configuration, in step S5 of molding the hardened body, the laminate 10 can be degassed while removing the excess slurry 4 from the laminate 10 using the vacuum bag 23. Therefore, air bubbles caused by the slurry 4 generated inside the laminate 10 can be suitably removed, and molding defects of the ceramic matrix composite material can be suppressed. In addition, since press processing using a mold is not performed, the length and size of the equipment required for molding can be suppressed.

[0035] In a second embodiment, the slurry 4 contains the ceramic powder 2 as a solute and water as a solvent.

[0036] According to this configuration, even if the slurry 4 contains moisture and is likely to form bubbles during molding, the degassing circuit member is provided, so that the bubbles can be suitably removed. The slurry 4 may contain a binder resin.

[0037] As a third aspect, in step S of forming the hardened body, a heater (heater mat 13) is arranged on the opposite side of the degassing circuit member in the stacking direction, sandwiching the laminate 10 therebetween, and heating is performed by the heater from one side of the stacking direction, while degassing is performed via the degassing circuit member from the other side of the stacking direction.

[0038] According to this configuration, heating and curing can be performed from the portion of the laminate 10 closest to the heat source, and degassing can be performed from the portion of the laminate 10 farthest from the heat source. Therefore, air bubbles generated inside the laminate 10 can be suitably removed, and the formation of voids can be suppressed.

[0039] As a fourth aspect, in step S5 of forming the hardened body, a pressure plate 21 that presses against the laminate 10 is disposed.

[0040] According to this configuration, the laminate 10 can be pressed uniformly by the pressing plate.

[0041] As a fifth aspect, the pressure plate has a through hole formed penetrating in the plate thickness direction.

[0042] According to this configuration, the laminate 10 can be deaerated via the pressure plate 21, so that the formation of voids can be further suppressed.

[0043] As a sixth aspect, in step S4 of forming the laminate 10, after the sheets are laminated, the slurry 4 is applied to the surfaces of the sheets.

[0044] According to this configuration, even if gaps are formed in the composite material, by applying the slurry 4, the gaps can be filled with the slurry 4, and therefore loss of the slurry 4 can be suppressed.

[0045] As a seventh aspect, in step S4 of forming the laminate, after the sheets are laminated, the laminate is covered with a vacuum bag, and the inside of the vacuum bag is evacuated.

[0046] According to this configuration, even if the composite material entraps air during lamination, the air can be removed by drawing a vacuum, so that the formation of voids can be suppressed. Moreover, by drawing a vacuum, it is possible to remove the excess slurry 4 as well as the air.

[0047] As an eighth aspect, in step S5 of forming the cured body, a gas-permeable release film is disposed between the laminate and the degassing circuit member.

[0048] According to this configuration, since the laminate 10 can be deaerated via the release film, the formation of voids can be further suppressed.

[0049] As a ninth aspect, in step S5 of forming the hardened body, a pressure plate (pressure plate 21) is arranged to press against the laminate 10, and the pressure plate has a larger pressed area that is pressed by the application of pressure than the pressing area pressing against the laminate.

[0050] According to this configuration, the pressure P2 applied to the pressing area can be made larger than the pressure P1 applied to the pressed area, so that the laminate 10 can be suitably pressed. [Explanation of symbols]

[0051] 1 Reinforced fiber sheet 2. Ceramic powder 3. Mixing device 4. Slurry 5 Impregnation tank 6 Prepreg 10 Laminate 11 Molding mold 12. Breatha 13 Heater mat 16 Forming materials 17a, 17b Peel ply 18 Dam Materials 20 Slurry remover 21 Pressure Plate 22 Breezer 23 Vacuum Bag 25 Sealing member

Claims

1. A method for forming a ceramic matrix composite material, comprising stacking sheets in which reinforcing fibers are impregnated with a slurry containing ceramic powder, curing the sheets, and then sintering the sheets to form a ceramic matrix composite material, comprising the steps of: stacking the sheets in a stacking direction to form a laminate; covering the laminate with a vacuum bag and drawing a vacuum inside the vacuum bag to form a cured body; In the step of molding the hardened body, a slurry remover for absorbing excess slurry is disposed on the laminate; a degassing circuit member is disposed on at least one side of the laminate for discharging air bubbles generated inside the laminate; and a heater is disposed on the opposite side of the degassing circuit member across the laminate in the stacking direction; A method for forming a ceramic-based composite material, in which heating is performed by the heater from one side in the stacking direction, and degassing is performed via the degassing circuit member from the other side in the stacking direction.

2. 2. The method for forming a ceramic composite material according to claim 1, wherein the slurry contains the ceramic powder as a solute and water as a solvent.

3. In the step of forming the hardened body, 3. The method for forming a ceramic composite material according to claim 1, further comprising the step of disposing a pressing plate for pressing said laminate.

4. 4. The method for forming a ceramic-based composite material according to claim 3, wherein the pressing plate has a through hole formed therethrough in the plate thickness direction.

5. In the step of forming the laminate, 5. The method for forming a ceramic composite material according to claim 1, further comprising the step of applying the slurry to the surfaces of the sheets after laminating the sheets.

6. In the step of forming the laminate, 6. The method for forming a ceramic composite material according to claim 1, further comprising the steps of: covering the laminate with a vacuum bag after laminating the sheets; and evacuating the inside of the vacuum bag.

7. In the step of forming the hardened body, 7. The method for forming a ceramic composite material according to claim 1, further comprising the step of: disposing a gas-permeable release film between said laminate and said degassing circuit member.

8. In the step of forming the hardened body, A pressing plate is disposed to press against the laminate, 8. The method for forming a ceramic composite material according to claim 1, wherein the pressing plate has an area to be pressed by pressure that is larger than an area for pressing the laminate.

9. A method for forming a ceramic matrix composite material, comprising stacking sheets in which reinforcing fibers are impregnated with a slurry containing ceramic powder, curing the sheets, and then sintering the sheets to form a ceramic matrix composite material, comprising the steps of: stacking the sheets in a stacking direction to form a laminate; covering the laminate with a vacuum bag and drawing a vacuum inside the vacuum bag to form a cured body; In the step of molding the hardened body, A slurry remover for absorbing excess slurry is disposed on the laminate, a deaeration circuit member is disposed on at least one side of the laminate for discharging air bubbles generated inside the laminate, and a pressure plate is further disposed to press against the laminate, The pressing plate has a through hole formed therethrough in the thickness direction of the plate.

10. A method for forming a ceramic matrix composite material, comprising stacking sheets in which reinforcing fibers are impregnated with a slurry containing ceramic powder, curing the sheets, and then sintering the sheets to form a ceramic matrix composite material, comprising the steps of: stacking the sheets in a stacking direction to form a laminate; covering the laminate with a vacuum bag and drawing a vacuum inside the vacuum bag to form a cured body; In the step of molding the hardened body, A slurry remover for absorbing excess slurry is disposed on the laminate, and a deaeration circuit member is disposed on at least one side of the laminate for discharging air bubbles generated inside the laminate; In the step of forming the laminate, The method for forming a ceramic composite material further comprises applying the slurry to the surfaces of the sheets after laminating the sheets.

11. A method for forming a ceramic matrix composite material, comprising stacking sheets in which reinforcing fibers are impregnated with a slurry containing ceramic powder, curing the sheets, and then sintering the sheets to form a ceramic matrix composite material, comprising the steps of: stacking the sheets in a stacking direction to form a laminate; covering the laminate with a vacuum bag and drawing a vacuum inside the vacuum bag to form a cured body; In the step of molding the hardened body, A method for molding a ceramic-based composite material, comprising: arranging a slurry removal material for absorbing excess slurry on the laminate; arranging a degassing circuit member on at least one side of the laminate for discharging air bubbles generated inside the laminate; and further arranging a gas-permeable release film between the laminate and the degassing circuit member.

12. A method for forming a ceramic matrix composite material, comprising stacking sheets in which reinforcing fibers are impregnated with a slurry containing ceramic powder, curing the sheets, and then sintering the sheets to form a ceramic matrix composite material, comprising the steps of: stacking the sheets in a stacking direction to form a laminate; covering the laminate with a vacuum bag and drawing a vacuum inside the vacuum bag to form a cured body; In the step of molding the hardened body, A slurry remover for absorbing excess slurry is disposed on the laminate, a deaeration circuit member is disposed on at least one side of the laminate for discharging air bubbles generated inside the laminate, and a pressure plate is further disposed to press against the laminate, The method for forming a ceramic-based composite material, wherein the pressing plate has a larger pressed area pressed by pressure compared to a pressing area pressing the laminate.

Images