JPH09202668A - Ceramic-based composite material of ceramic continuous filament and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a low-cost ceramic composite material having high reliability and durability. SOLUTION: This ceramic-based composite material of ceramic continuous filaments has a constitutional structure comprising a ceramic sintered compact as a matrix substrate, the ceramic continuous filaments as a reinforcing material dispersed and compounded in the ceramic sintered compact and a phase of a glassy composition formed on the surface of the ceramic continuous filaments. Plural yarns (yarn bundles) of the ceramic continuous filaments are horizontally arranged at an optional width, immersed and passed through a slurry of ceramics for filling a matrix containing a sintering assistant of a glass composition while being continuously pulled, then horizontally arranged at an optional width on a carrier film, fixed and dried to prepare monolayered sheetlike prepregs of green ceramics reinforced with the ceramic continuous filaments. The plural sheets of the prepregs are then laminated in an optional direction, sintered and compounded at a temperature below the thermal deteriorating temperature of the ceramic continuous filaments under suitable pressurizing conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic-based long fiber composite material, which is dense and has excellent strength and toughness values, and is particularly required to have high mechanical properties and reliability at high temperatures. , Aircraft parts,
The present invention relates to a ceramic-based ceramic long-fiber composite material suitable as a structural component such as a nuclear component and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a ceramic sintered body has a small strength decrease even at high temperatures and is excellent in various characteristics such as hardness, electric insulation, abrasion resistance, heat resistance, corrosion resistance and light weight as compared with a metal material. Therefore, it is used in a wide range of fields as electronic materials and structural materials such as heavy electric equipment parts, aircraft parts, automobile parts, electronic parts, precision equipment parts and semiconductor materials.

[0003] However, the ceramics sintered body is weaker in tensile stress than compression, and has a defect of so-called brittleness, in which fracture progresses in an instant under tensile stress, so-called brittleness. The current situation is that it is difficult to obtain sufficient reliability against external force. From such a thing,
In order to make it possible to apply ceramic parts to parts requiring high reliability in strength, it is strongly required to increase the toughness and increase the fracture energy of the ceramic sintered body.

That is, in ceramic structural parts used for gas turbine parts, aircraft parts, automobile parts, etc., high reliability is required in addition to heat resistance and high temperature strength. Therefore, research on practical application of ceramics composite materials in which reinforcing materials made of inorganic substances and metals, whiskers, plates, particles, and other reinforcing materials are dispersed and composited in a matrix sintered body to increase toughness and fracture energy values Are being promoted by research institutes.

It is known that, among the above-mentioned ceramic composite materials, those using long fibers as a reinforcing material have a great effect on the improvement of reliability because the fracture toughness and the fracture energy are increased. . At present, two-dimensional or three-dimensional woven fabrics have been tried to be applied as means for applying long-fiber composite materials to parts having complicated shapes, and as a method for filling monolithic ceramics as a matrix of long-fiber ceramics fabrics, The CVI method (chemical vapor impregnation method) and the bricarcer method are adopted.

However, in any of the above methods, it is difficult to increase the fiber volume ratio, and it takes a very long time to increase the ceramic matrix impregnation ratio.

[0007]

The conventional ceramic-based long-fiber composite materials have low strength and fracture toughness when the fiber volume ratio is low or the ceramic matrix impregnation ratio is low. The above mechanical properties expected as a material cannot be obtained.

Further, in the conventional method for producing a ceramic-based long-fiber composite material, the production equipment is expensive, the production requires a long time, and the strength, fracture toughness value and fracture are other than the CVI method which is an extremely expensive material. At present, energy has not reached the expected level.

Therefore, the present invention is an equipment which is cheaper than the equipment of the CVI method and improves the fiber volume ratio and the matrix impregnation ratio of the monolithic ceramics as compared with other conventional methods, and the initial fracture strength and fracture toughness value and It is an object of the present invention to provide a low-cost ceramic-based ceramic long-fiber composite material having high reliability and durability by increasing the breaking energy.

[0010]

The ceramic-based ceramic long-fiber composite material of the present invention comprises a ceramic sintered body as a matrix substrate, and a ceramic long-fiber as a reinforcing material dispersed and composited in the ceramic sintered body. ,
It has a texture structure composed of a glass composition phase formed on the surface of a long ceramic fiber.

Further, the ceramic-based ceramic long-fiber composite material of the present invention is obtained by adhering and drying a slurry of matrix-filling ceramics to a yarn (yarn bundle) of ceramic long-fibers to prepare a prepreg of raw ceramics reinforced with long-fiber ceramics. Was prepared, a plurality of these prepregs were laminated in arbitrary directions, and sintered under appropriate pressure conditions to form a composite. The prepreg may have a sheet shape or a wire shape.

Further, the ceramic-based ceramic long-fiber composite material of the present invention is obtained by immersing and passing a plurality of yarns (yarn bundles) of long-fiber ceramics in a slurry of matrix-filling ceramics to give an arbitrary width on a carrier film. The prepregs are made of monolayer sheets of raw ceramics reinforced with long ceramic fibers, and are laminated in any direction, and sintered under appropriate pressure conditions. It is a composite.

An auxiliary agent having a glass composition is added as a sintering agent to the slurry of the ceramics for filling the matrix so that the sintering temperature becomes equal to or lower than the thermal deterioration temperature of the ceramic long fibers.

The ceramic as the matrix base material is Al ₂ O ₃ , and the ceramic long fiber as the reinforcing material is S
iC long fiber, ceramic as the matrix base material is SiC, and ceramic long fiber as the reinforcing material is Si
C long fiber, ceramics as matrix base material is S
With i ₃ N ₄ , ceramic long fibers as a reinforcing material are Si
C long fibers, ceramics as matrix base material are A
l ₂ O ₃ and long ceramic fibers as a reinforcing material are Al
It can be a combination that is ₂ O ₃ long fibers.

The ceramic-based ceramic long-fiber composite material as described above is made up of a plurality of yarns (yarn bundles) of continuous continuous-fiber ceramics which are horizontally arranged in an arbitrary width and continuously pulled, while a sintering aid having a glass composition. Immersing and passing through a slurry of matrix-filling ceramics containing, laying horizontally on a carrier film to an arbitrary width and fixing and drying, to prepare a prepreg in the form of a monolayer sheet of raw ceramics reinforced with ceramic long fibers, Laminate a plurality of this prepreg in any direction, under appropriate pressure conditions,
It can be manufactured by sintering at a temperature lower than the thermal deterioration temperature of the long ceramic fibers to form a composite.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the ceramic as a matrix substrate is Al ₂ O ₃ (alumina) and the ceramic long fibers as a reinforcing material are SiC long fibers will be described below.

FIG. 1 is a flow chart showing the manufacturing process of the Al ₂ O ₃ ceramics-based SiC ceramics long fiber composite material of this embodiment.

The matrix-filling ceramics slurry is prepared by mixing Al ₂ O ₃ powder, a glass composition auxiliary agent, and a sintering auxiliary agent, adding a dispersant, ethanol, and distilled water, and subjecting to primary pulverization with a ball mill. After that, a binder, a plasticizer, and distilled water were injected to carry out secondary pulverization, and then they were well mixed and vacuum degassed. In this embodiment, the Al ₂ O ₃ powder has an average particle size of 1.1 μm and a purity of 99.5% or more {Showa Denko KK (α-alumina AL45-1) etc.},
The sintering aid of the glass composition is SiO ₂ -B ₂ O ₃ -based glass powder, the binder is HB-500, and the dispersant is LCD-.
40B (all manufactured by Lion), SiC long fibers are Tyranno fiber (manufactured by Ube Industries (Si-Ti-C-O fiber): hereinafter (SiC fiber). } Is used.

The glass composition aid (SiO ₂ —B ₂ O ₃ -based glass powder) is blended for the purpose of lowering the ceramics sintering temperature in order to prevent thermal degradation of the SiC long fibers during firing. It Further, as will be described later, by adding an optimum amount of the glass composition auxiliary agent to the slurry, a phase of the glass composition is generated on the surface of the ceramic long fiber in the structure structure of the composite material after firing, and the reinforcing fiber / The interfacial properties of the matrix substrate are improved.

Al ₂ O ₃ for matrix filling as described above
A prepreg of raw Al ₂ O ₃ ceramics reinforced with SiC ceramics long fibers is prepared by using the slurry of (1) and a yarn (thread bundle) of SiC long fibers.

The prepreg can be produced, for example, by a method (improved doctor blade method) conceptually shown in FIG. That is, while a plurality of yarns (thread bundles) of continuous SiC filaments are horizontally arranged in an arbitrary width and continuously pulled (carrier speed is about 30 cm / min), the slurry produced as described above is dipped in the slurry. It can be produced by allowing the particles to pass through, horizontally arranging them on a carrier film in an arbitrary width, and fixing and drying.

Then, the monolayer sheet-shaped prepreg produced as described above is cut into an appropriate size,
The carrier film is peeled off, and the yarn direction of the SiC long fibers is sequentially selected in an appropriate direction and laminated. The prepreg may be laminated by sequentially changing the crossing angle in the yarn direction. For example, the yarns may be sequentially laminated at 90 ° intersections or 0 °, 45 ° right, 45 ° left, and then 90 ° to the yarn directions of the first prepreg.

After laminating the prepregs, the prepregs are integrated by press-pressing or the like, and the prepregs are fired in a high-temperature heating furnace under an appropriate temperature condition, an atmospheric pressure or an appropriate pressurizing state, whereby the Al ₂ O _{3 of} this embodiment is formed. A ceramic-based SiC ceramic long fiber composite material can be manufactured.

The firing temperature is set to a sintering aid that produces a glass phase (in this embodiment, a SiO ₂ —B ₂ O ₃ -based aid).
The composition temperature of the composite ceramic material is greatly influenced by the mechanical properties of the composite ceramic material, that is, the fracture strength and fracture toughness. Therefore, it is necessary to optimize the firing temperature and the glass composition. As a result of the test, the firing temperature was 950 ° C., and the weight mixing ratio of Al ₂ O ₃ as the matrix base material and the glass composition agent was 6: 4. It has been found that sometimes the best results are obtained.

[0025]

EXAMPLE FIG. 3 shows the case where the weight ratio of Al ₂ O ₃ powder and SiO ₂ —B ₂ O ₃ -based glass powder is 6: 4 {(alumina / glass) = (6/4)}. this example product in: and (Si-Ti-C-O / Al 2 O 3 composite white ○ in the figure), monolithic ceramics material: for the (Al ₂ O ₃ material black ○ in the figure), the intensity ( The results of a comparative test of the effect of the firing temperature on the tensile strength) are shown.

As shown in the figure, Si--Ti--C--O /
The Al ₂ O ₃ composite material has firing temperatures of 950 ° C. and 1000 ° C.
In the case of C, the strength is remarkably improved as compared with the monolithic ceramics Al ₂ O ₃ material, and especially the firing temperature is 950 °.
The highest intensity value is obtained when C is set. For Al ₂ O ₃ which is the matrix base material, the firing temperature is 950 ° C.
Indicates the highest intensity value. The strength is lowered below these firing temperatures because of the firing degree of Al ₂ O ₃ as a matrix substrate and the reinforcing fibers (Si-Ti-
It is considered that the generation of the phase of the glass composition is insufficient at the interface of the C—O fiber) / matrix substrate (Al ₂ O ₃ sintered body). In addition, it is considered that the strength is lowered due to the thermal deterioration of the Si—Ti—C—O fiber when the firing is performed at the firing temperature or higher. Therefore, the firing temperature is 950 ° C
It is most preferably about 1000 ° C, especially about 950 ° C.

[0027] Figure 4 is fired the Si-Ti-C-O / Al 2 O 3 composite and monolithic ceramic Al ₂ O ₃ material of the tensile stress at the firing temperature 950 ° C - indicates the strain curve.

First, monolithic ceramics Al ₂ O ₃
While the deformation and fracture of the material progresses linearly, Si-Ti-
Deformation and Fracture of C-O / Al ₂ O ₃ composite is noted that it progresses in a non-linear. Further, Si-Ti-C-O / Al 2 O 3
In the composite material, the maximum strain and the maximum strain stress (x point shown in the same figure), and the fracture absorption energy (integral value of stress-strain curve) are monolithic ceramics Al ₂ O ₃
Significantly improved compared to wood. From this, it can be said that the Si—Ti—C—O / Al ₂ O ₃ composite material of this example is a material having much higher toughness than the monolithic ceramic Al ₂ O ₃ material.

FIGS. 5 and 6 show (alumina / glass).
The relationship between the composition ratio and the tensile fracture strength (KIC) is shown. FIG. 5 shows the results when the firing temperature is 950 ° C., and the breaking strength shows the maximum value when (alumina / glass) = (6/4). Further, FIG. 6 shows the firing temperature as 100
These are the results when the temperature is 0 ° C (alumina / glass).
The maximum value is shown when = (4/6). in this way,
Si-Ti-C-O / Al 2 O 3 composite of this Example,
It was confirmed that the fracture strength was improved to about 2 to 6 times as compared with the monolithic ceramic Al ₂ O ₃ material.

7 and 8 show the above Si-Ti-C-
The fracture surface in the tensile test of the O / Al ₂ O ₃ composite material is shown (broken surface SEM photograph). FIG. 7 shows a firing temperature of 850 °
8 shows the fracture surface when the firing temperature is 950 ° C. In the fracture surface shown in FIG. 7 (firing temperature 850 ° C.), there is no evidence that Si—Ti—C—O fibers remain. This indicates that the interfacial properties of the reinforcing fiber / matrix substrate are not good, leading to fracture in a somewhat brittle manner. on the other hand,
In the fracture surface shown in FIG. 8 (firing temperature 950 ° C.), Si-T
The i-C-O fiber remains, and a drawing length of about 50 μm is obtained. This is a reinforcing fiber (Si-Ti
-C-O fibers) / matrix substrate (Al ₂ O ₃ sintered body)
Since the interfacial properties of the glass composition were improved by the phase of the glass composition formed on the surface of the Si-Ti-C-O fiber, the firing temperature could be lowered by incorporating the sintering aid of the glass composition. Thereby, the reinforcing fiber (Si-Ti
It is considered that the thermal deterioration of (—C—O fiber) was suppressed. That is, in the ceramic-based ceramic long-fiber composite material of this example, the important factors for improving the mechanical properties such as fracture strength and fracture toughness value and fracture energy are:
A glass composition phase is generated on the surface of the reinforcing fiber, improving the drawability by improving the interfacial characteristics of the reinforcing fiber / matrix base material, and strengthening by lowering the firing temperature below the thermal deterioration temperature of the reinforcing fiber. It is considered to improve the strength of the fiber.

The ceramics used as the matrix substrate and the ceramic long fibers used as the reinforcing material are not limited to the above-exemplified materials, and the combinations described in the claims and combinations of various other ceramic materials are adopted. be able to. It is also possible to produce a composite material by appropriately combining and stacking prepregs made of different kinds of ceramic materials and firing them. For example, monolayer sheet prepregs made of different ceramic materials are sequentially laminated so as to have a gradient in thermal expansion, and sintered under appropriate pressure conditions to form a composite, so that the surface layer has a thermal gradient. be able to. Furthermore, a BN coat or the like may be applied to the surface of the yarn of ceramic long fibers as a reinforcing material.

[0032]

The present invention has the following effects. (1) The ceramic-based ceramic long-fiber composite material of the present invention has a high fiber volume ratio and a matrix impregnation ratio of monolithic ceramics, is excellent in mechanical properties such as strength and fracture toughness value and fracture energy, and has high reliability and durability. Have. In addition, it can be manufactured in a relatively short period of time with equipment that is less expensive than the equipment of the conventional CVI method, and is economically superior. (2) Ceramic long-fiber-reinforced green ceramic prepreg, in which slurry of matrix-filling ceramics is adhered to and dried on a yarn (thread bundle) of long-ceramics, can be stored for a long period of time and has an appropriate size when needed. It is extremely convenient and economical because it can be cut into pieces. In addition, the required properties such as strength, hardness, linear expansion coefficient, etc. can be optimally adjusted by selecting the materials of the matrix base material and the long fibers, the number of layers, the direction of lamination, etc., so that the application range is extremely wide.

[Brief description of drawings]

FIG. 1 is a flowchart showing manufacturing steps.

FIG. 2 is a cross-sectional view (FIG. A) and a plan view (FIG. B) conceptually showing a method of manufacturing a prepreg.

FIG. 3 is a diagram showing a test result of firing temperature-tensile strength.

FIG. 4 is a diagram showing stress-strain test results.

FIG. 5 is a diagram showing a test result of composition ratio-breaking strength (calcination temperature: 950 ° C.).

FIG. 6 is a view showing a test result of composition ratio-breaking strength (calcination temperature: 1000 ° C.).

FIG. 7 is a SEM photograph of a fracture surface in a tensile test (firing temperature 850 ° C.).

FIG. 8 is an SEM photograph of a fracture surface in a tensile test (firing temperature 950 ° C.).

Claims (9)

[Claims] 1. A ceramics sintered body as a matrix substrate, ceramics long fibers as a reinforcing material dispersed and composited in the ceramics sintered body, and a glass composition phase formed on the surface of the ceramics long fibers. A ceramic-based ceramic long-fiber composite material having the following structure structure. 2. A yarn (yarn bundle) of long ceramic fibers.
Then, a slurry of matrix filling ceramics is attached and dried to prepare a prepreg of raw ceramics reinforced with long ceramic fibers, and the prepregs are laminated in a plurality of arbitrary directions and sintered under an appropriate pressure condition to form a composite. Ceramic-based ceramic long-fiber composite material characterized by 3. A ceramic filament is obtained by immersing and passing a plurality of yarns (thread bundles) of ceramic long fibers in a slurry of ceramics for matrix filling, horizontally arranging them on a carrier film in an arbitrary width and fixing and drying. A ceramic-based ceramic length characterized by producing a mono-layer sheet prepreg of fiber-reinforced raw ceramics, laminating a plurality of prepregs in an arbitrary direction, and sintering them under appropriate pressure conditions to form a composite. Fiber composite material. 4. A glass composition aid is added as a sintering aid to the slurry of the ceramics for matrix filling so that the sintering temperature becomes equal to or lower than the thermal deterioration temperature of the ceramic long fibers. Alternatively, the ceramic-based ceramic long-fiber composite material according to item 3. 5. A ceramic as a matrix base material is Al ₂ O ₃ and a ceramic long fiber as a reinforcing material is a SiC long fiber.
Alternatively, the ceramic-based ceramic long-fiber composite material according to item 4. 6. The ceramic as a matrix base material is SiC, and the ceramic long fiber as a reinforcing material is S.
The ceramic-based ceramic long-fiber composite material according to claim 1, 2, 3 or 4, which is an iC long-fiber. 7. The ceramic as a matrix base material is Si ₃ N ₄ , and the ceramic long fibers as a reinforcing material are SiC long fibers.
Alternatively, the ceramic-based ceramic long-fiber composite material according to item 4. 8. The ceramic material as a matrix substrate is Al ₂ O ₃ , and the ceramic long fibers as a reinforcing material are Al ₂ O ₃ long fibers.
The ceramic-based ceramic long-fiber composite material according to 3 or 4. 9. A continuous ceramic continuous filament yarn (yarn bundle) is arranged horizontally in an arbitrary width and continuously drawn while being immersed in a slurry of a ceramic for matrix filling containing a sintering aid having a glass composition.・ Passing, horizontally arranging horizontally on a carrier film to an arbitrary width, and fixing and drying to prepare a monolayer sheet prepreg of raw ceramics reinforced with ceramic long fibers, and laminating a plurality of these prepregs in an arbitrary direction, A method for producing a ceramic-based ceramic long-fiber composite material, which comprises sintering at a temperature not higher than the thermal deterioration temperature of the long-fiber ceramics to form a composite under appropriate pressure conditions.