JP2019195938A - Method for producing prepreg sheet for pressurization-hot molding of 2d-ceramic fiber-reinforced composite material with cylinder shape - Google Patents

Abstract

To suppress characteristic deterioration caused by thread breakage in reinforcing ceramic fiber as a component of prepreg sheets as an intermediate stock for producing a ceramic composite material upon molding by heating-pressurization by molding a preform according to the lamination of the prepreg sheets.SOLUTION: A prepreg sheet as an intermediate stock for producing a ceramic composite material is subjected to corrugation working (corrugation shape application), and the same is laminated to mold a preform, thus the thread breakage of reinforcing ceramic fiber caused by volume shrinkage in heating-pressurization is suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a prepreg sheet for pressurizing and thermoforming a cylindrical 2D-ceramic fiber reinforced composite material.

  The NITE method (shown in related patents) is a production method that can achieve high density and high crystallinity in the production of a cylinder-shaped bi-directional (2D) ceramic fiber reinforced composite material. In order to produce by this method, a preform is produced using a prepreg sheet as an intermediate material, and is molded by pressurizing and heating the preform to produce a final product. When creating a cylindrical 2D-ceramic fiber reinforced composite material product using the conventional NITE prepreg sheet, the wall thickness decreases due to volume shrinkage during pressure and heat molding, and the perimeter increases toward the inner surface. To increase. At this time, since the ceramic fiber does not undergo plastic deformation under the manufacturing conditions, it is partially broken, which causes a decrease in strength and is a big problem in increasing the size of the cylinder.

  When making a large cylinder, the thickness and length of the prepreg sheet decrease due to volume shrinkage during pressurization and heat molding. The former is due to the densification of the matrix components, and the matrix mainly composed of nanopowder has a sufficient deformation capacity, and a high-density and highly crystalline matrix can be formed. On the other hand, there is no problem in the deformation of the matrix part due to the increase in length, but the ceramic fiber does not deform under this molding condition, and the fiber breaks to cope with the matrix deformation. Tend to grow. FIG. 1 shows a phenomenon that occurs during molding of a preform using a prepreg sheet in a conventional method. Reference numeral 1 denotes a unidirectional prepreg sheet, and FIG. The laminated ploypreg sheet is wound around a core material to form a preform, and the state in which the preform with the core material removed is inserted into a die matched to the outer diameter of the product is 3. In the state of 3, it is molded by applying internal pressure and heating. In this case, 4 shows a state in which the fiber is disconnected because it does not have sufficient ductility. This is a drawback of this method that causes deterioration of characteristics.

  This drawback in the production of large cylinders is a major obstacle to ensuring the strength characteristics required for the cylinder. Specifically, it is necessary to reinforce more fibers to compensate for this drawback, which greatly impairs the superiority of the material in terms of price and weight.

  As an improvement measure, we devised a method for corrugating the prepreg sheet. By using this prepreg sheet (hereinafter referred to as undulating prepreg sheet), even when manufacturing large cylinders, the corrugated fibers show straightness during molding, so that the required circumference can be increased. The fiber reinforced structure which draws a concentric circle in the cross section of the product can be achieved. FIG. 2 is an explanatory diagram for illustrating a molding process of a large cylinder by this method, and is an explanatory diagram in a cross-sectional direction of the cylinder. In FIG. 2, 5 is a corrugated prepreg sheet, and 6 is a tubular preform with a corrugated prepreg sheet attached thereto. It is shown in 7 that it is possible to produce a large cylinder without thread breakage by molding this tubular preform with internal pressure. However, even with this method, it is necessary to accurately design the preform shape and the shrinkage rate at the time of molding, and to give the minimum necessary corrugated shape. For this purpose, the fiber characteristics, the component of the matrix component Design is important.

Patent No. 4536950

  Thickness decreases due to volumetric shrinkage during pressure and heat forming, which is a problem when creating a cylinder-shaped 2D-ceramic fiber reinforced composite material product using the conventional NITE prepreg sheet. As a result of the large increase in the circumference toward the surface, the ceramic fibers are disconnected, causing a decrease in strength. The present invention can cope with an increase in circumference required by producing a prepreg sheet that has been corrugated (provided with a corrugated shape), and can achieve a fiber-reinforced structure that draws concentric circles within a perfectly circular product cross section.

  The problem to be solved is that the fiber breaks when a large cylinder is molded, and sufficient strength cannot be obtained.

  The present invention relates to a method for corrugating (providing a corrugated shape) to a prepreg sheet, which is an intermediate material of a ceramic composite material large cylinder or a similar shaped product by the NITE method, and a large ceramic composite material using the intermediate material It is characterized by manufacturing a cylinder.

  By using the prepreg sheet that has been corrugated (provided with corrugated shape) according to the present invention, there is an advantage that the problem of fiber breakage when a large-sized cylinder or a product having a similar shape is produced with a bi-directional reinforced ceramic composite material can be solved .

FIG. 1 is an explanatory view showing a molding process of a 2D-fiber reinforced ceramic composite cylinder using a conventional NITE prepreg sheet. Example 1 FIG. 2 is an explanatory view showing a process of manufacturing a large cylinder or a product having a similar shape with a bi-directionally reinforced ceramic composite material by using a prepreg sheet that has been corrugated (giving a corrugated shape) according to the present invention. (Example 2) FIG. 3 is a molding example of a cylinder made of 2D-fiber reinforced ceramic composite material using a conventional NITE prepreg sheet, and yarn breakage is clearly recognized. In the product using the prepreg sheet in the method of the present invention, yarn breakage is not recognized, and a smooth cylinder surface is obtained. FIG. 4 is an example of forming a cylinder using a prepreg sheet that has been corrugated (giving a corrugated shape), which is a product of the present invention. In the enlarged cross-sectional view (lower left), a straightened fiber array is observed. Moreover, thread breakage is not recognized.

  A cylinder having a diameter of 40 mm, which is larger than the conventional annular product having a diameter of 10 mm, was molded by an internal pressure method.

  FIG. 1 is a cross-sectional view (concept) of an embodiment showing a process of manufacturing a cylinder using a conventional prepreg sheet by the NITE method as a premise of the present invention. .

  FIG. 2 illustrates the concept of the large cylinder manufacturing process in the present invention. The corrugated prepreg sheet 5 is designed so that the actual fiber length in the corrugated prepreg corresponding to the radial length in the preform state matches the radial fiber length after molding. The preform 6 shows a state in which a corrugated prepreg sheet designed in this way is molded into a tubular preform and inserted into a block when molded by an internal pressure type. 7 shows that the large cylinder is molded by internal pressure molding, the thickness of the preform is greatly reduced, and the wavy fibers are straight but not broken. Yes.

  As an example, a cross-sectional structure of a cylinder made of SiC / SiC composite material is shown in FIG. Fig. 4 shows the appearance of the product.

  Large cylinder material that exhibits excellent strength characteristics, especially high strength as a ceramic material and brittleness, which is a drawback of ceramic materials, and exhibits pseudo-ductility is only a strength member as a material for ultra-high temperature, highly corrosive atmosphere and other harsh environments In addition, it can be used in a wide range of fields as a material that also has a role as a functional material. In particular, the excellent crystallinity and high airtightness derived from high density, which are the characteristics of the NITE method, are at a level that cannot be achieved with other ceramic composite materials. Regeneration represented by nuclear and nuclear fusion fields and supercritical geothermal power generation. It can also be used in applications where excellent environmental resistance in the energy field is essential.

DESCRIPTION OF SYMBOLS 1 Unidirectional prepreg sheet 2 Laminated prepreg sheet 3 Tubular preform by a normal system 4 Pipe expansion by internal pressure (thread breakage)
5 Corrugated prepreg sheet 6 Tubular preform with corrugated prepreg sheet 7 Tube expansion by internal pressure (no thread breakage)

Claims (2)

  A method of corrugating (providing corrugated shape) to a prepreg sheet, which is an intermediate material used for molding using heating and pressurization when creating a cylinder or similar shaped product with a fiber reinforced ceramic composite material A preform is prepared using the prepreg sheet according to claim 1, and a cylinder or a similar shaped product is formed using the fiber reinforced ceramic composite material.

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