JPH04243971A - Coated fiber reinforced functionally graded material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated fiber-reinforced functionally graded material having a silicon carbide coating layer with excellent oxidation resistance and at the same time having excellent high-temperature strength properties.

0002

[Prior Art] Fiber-reinforced composite materials, which have a matrix of ceramics such as carbon or SiC and contain carbon fibers or ceramic fibers such as SiC as reinforcing materials in this matrix, exhibit excellent strength characteristics even at high temperatures and are resistant to fracture. Due to its high toughness and high reliability, it has attracted particular attention in recent years as an aerospace material.

However, among the above fiber reinforced composite materials,
Carbon fiber reinforced composite material whose reinforcing material is carbon fiber is 150
Although it has excellent strength properties even at high temperatures exceeding 0°C, it lacks oxidation resistance for use as an aerospace material. Therefore, SiC, which has excellent oxidation resistance, is
Although a coating layer is coated on the surface, the thermal expansion coefficient of the base carbon fiber reinforced composite material is extremely small compared to that of the SiC coating layer, so the Si
There was a drawback that the C coating layer peeled off or was destroyed.

On the other hand, in ceramic fiber-reinforced composite materials that use ceramic fibers such as SiC as reinforcing materials, peeling or destruction of the SiC coating layer due to mismatch in thermal expansion coefficient does not occur, but ceramic fibers Since the strength decreased, the strength properties at high temperatures were insufficient.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional circumstances, the present invention provides a SiC coating layer that does not peel or break due to mismatching of thermal expansion coefficients and maintains excellent strength characteristics even at high temperatures of 1500° C. or higher. The purpose of this invention is to provide a coated fiber-reinforced composite material that can be used as a composite material.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present inventors used both carbon fibers and ceramic fibers as reinforcing materials, and provided a coating in which the composition of the carbon fibers and ceramic fibers in the base material was graded. We have developed a fiber-reinforced functionally graded material.

That is, in the case where the coated fiber-reinforced functionally graded material of the present invention is provided with a SiC coating layer on the front and back surfaces of the base material, the coated fiber-reinforced functionally graded material is made of carbon, a carbide or nitride of an element of group 4A of the periodic table, silicon or boron. A fiber-reinforced composite material base material containing carbon fibers and ceramic fibers as reinforcing materials in a matrix consisting of at least one type of carbonitride or carbonitride, and a silicon carbide coating layer provided on both surfaces of the base material. , the reinforcing material on both surfaces of the base material is made of ceramic fibers, the reinforcing material in the center part is made of carbon fibers, and the reinforcing material in the middle part is made of both carbon fibers and ceramic fibers, and the carbon fiber content in the reinforcing material is It is characterized by a nearly continuous change from 100% at the center to 0% at both surfaces.

[0008] In addition, when providing a SiC coating layer only on one surface of the base material, carbon, or an element of group 4A of the periodic table,
A base material of a fiber-reinforced composite material containing carbon fibers and ceramic fibers as reinforcing materials in a matrix consisting of at least one of silicon or boron carbides, nitrides, or carbonitrides, and a fiber-reinforced composite material provided on one surface of the base material. The reinforcing material on one surface of the base material is ceramic fiber, the reinforcing material on the other surface is carbon fiber, and the reinforcing material in the middle is made of both carbon fiber and ceramic fiber. , the carbon fiber content in the reinforcement is 0 on one surface.
It is characterized in that it changes almost continuously from % to 100% on the other surface.

[0009]

[Function] In the present invention, by arranging a ceramic fiber-reinforced composite material whose reinforcing material is ceramic fiber on the surface portion of the base material on which the SiC coating layer is provided, SiC
It improves the mismatch in thermal expansion coefficient with the coating layer, prevents peeling and destruction of the SiC coating layer under thermal cycles, and provides excellent oxidation resistance and thermal shock resistance.

At the same time, by arranging a carbon fiber-reinforced composite material whose reinforcing material is carbon fiber in the center of the base material or the surface area on the side where the SiC coating layer is not provided, the material can withstand even high temperatures of 1500°C or higher. It is possible to maintain excellent strength properties.

Furthermore, the middle part of the base material is reinforced with both carbon fiber and ceramic fiber, and the carbon fiber content is varied from the center part or the other surface part where no SiC coating layer is provided to one surface where the SiC coating layer is provided. Since the composition has a gradient composition that changes almost continuously up to the end, it is possible to alleviate the inconsistency in the coefficient of thermal expansion within the base material.

[0012] The SiC coating layer can be formed using the usual CVD method or PV method.
It can be formed by method D.

[0013]

[Example 1] Ti with an average particle size of 2 μm as a matrix
Using C powder, a small amount of Al2O3 powder is mixed with it, then kneaded with acrylamide resin, and applied on a woven fabric of SiC fibers to form a SiC/TiC powder made of SiC fibers and TiC powder.
A TiC composite sheet ■ was obtained. Next, TiC powder with an average particle size of 2 μm was used as a matrix, and a small amount of A was added to it.
After mixing the 12O3 powder, it was kneaded with an acrylamide resin and coated on a carbon fiber woven fabric to obtain a C/TiC composite sheet (2) consisting of carbon fibers and TiC powder.

[0014] These composite sheets ■ and ■ are combined to form a set of three SiC/TiC composite sheets ■ (3 sheets in total).
- 3 sets of 2 SiC/TiC composite sheets + 1 C/TiC composite sheet (9 sheets in total) - 3 sets of 1 SiC/TiC composite sheet + 1 C/TiC composite sheet ( 6 sheets in total) - SiC/TiC composite sheet ■ 1 sheet + C/
TiC composite sheet ■ 3 sets of 2 sheets (9 sheets in total) - C/Ti
C composite sheet ■ 3 sheets in 1 set (total 3 sheets), total 3 sheets
0 sheets were laminated. Thereafter, the laminate was heated at 500°C for 3 hours to remove volatiles, and then pressure sintered at 2000°C for 2 hours at a pressure of 200 kg/cm2 to form a C to SiC material measuring 50 mm long x 50 mm wide x 5 mm high. Fiber reinforced TiC composite material (C~Si
C/TiC composite material) was manufactured.

When the thermal expansion coefficient in the plane direction of this C~SiC/TiC composite material was measured, it was found that the SiC/TiC surface portion was 4.4×10 −6 K−1 and the C/TiC surface portion was 1.4×10 −6 K−1.
It was 2×10-6K-1. Next, this C~SiC/
TiC composite material is used as the base material, and SiCl4 is used as the raw material gas.
, CH4, and H2, the base material SiC
/SiC on TiC surface (thermal expansion coefficient 4.5 x 10-6K
-1) was coated to a thickness of about 500 μm.

Coatings C to S of the present invention produced as described above
The bending strength of the iC/TiC composite material was measured at room temperature and at 1500°C. Also, in the atmosphere from room temperature to 1
A thermal cycle up to 700° C. was repeated 10 times, and the room temperature strength after the thermal cycle was measured and the state of the SiC coating layer was observed. The results are shown in Table 1.

As a comparative example, the TiC matrix was replaced with Si
We produced a coated SiC/TiC composite material in which a SiC coating layer was formed on a base material reinforced only with C fibers, and a coated C/TiC composite material in which a SiC coating layer was provided on a base material in which a TiC matrix was reinforced only with carbon fibers. , the same test as above was conducted and the results are shown in Table 1.

[0018]

[Table 1]

[0019]

[Example 2] Si with an average particle size of 2 μm as a matrix
Using 3N4 powder, a small amount of Al2O3 powder was mixed with it and then kneaded with acrylamide resin to form Si-Ti-
Si-Ti-C fibers and Si3 are coated on a woven fabric of C fibers.
A Si-Ti-C/Si3N4 composite sheet (2) consisting of N4 powder was obtained. In addition, as a matrix, the average particle size is 2 μm.
After mixing a small amount of Al2O3 powder with this Si3N4 powder, it was kneaded with an acrylamide resin and coated on a carbon fiber woven fabric to obtain a C/Si3N4 composite sheet consisting of carbon fibers and Si3N4 powder. Ta.

These composite sheets ■ and ■ were combined in the same manner as in Example 1, and a set of three Si-Ti-C/Si3N4 composite sheets ■ (3 sheets in total) -Si-Ti-C/Si
3N4 composite sheet ■ 2 sheets + C/Si3N4 composite sheet ■ 3 sets of 1 sheet (total 9 sheets) - Si-Ti-C
/Si3N4 composite sheet ■ 1 sheet + C / Si3N4 composite sheet ■ 3 sets (total 6 sheets) - Si-Ti-C
/Si3N4 composite sheet ■ 1 sheet + C/Si3N4 composite sheet ■ 3 sets of 2 sheets (9 sheets in total) - C/Si3N4
Composite sheet ■ 3 sheets in 1 set (total of 3 sheets), total 30
Laminated. Thereafter, the laminate was treated in the same manner as in Example 1 to make a C~Si-Ti-C fiber-reinforced Si3N4 composite (C
~Si-Ti-C/Si3N4 composite material) was manufactured.

Obtained C~Si-Ti-C/Si3N4
When the thermal expansion coefficient in the plane direction of the composite material was measured, it was found that Si
-Ti-C/Si3N4 surface area is 3.2 x 10-6K-
1 and C/Si3N4 surface area is 0.6×10-6K-1
It was hot. Next, this C~Si-Ti-C/Si3N4
A composite material is used as a base material, and the base material is Si-T in the same manner as in Example 1.
The i-C/Si3N4 surface was coated with SiC to a thickness of about 500 μm.

Coatings C to S of the present invention produced as described above
The bending strength of the i-Ti-C/Si3N4 composite material was measured at room temperature and at 1500°C. Further, thermal cycles from room temperature to 1700° C. were repeated 10 times in the air, and the room temperature strength after the thermal cycles was measured and the state of the SiC coating layer was observed. The results are shown in Table 2.

As a comparative example, a coated Si-Ti-C/Si3N4 composite material was prepared in which a SiC coating layer was formed on a base material in which a Si3N4 matrix was reinforced with only Si-Ti-C fibers.
A coated C/Si3N4 composite material was produced in which a SiC coating layer was provided on a base material in which a Si3N4 matrix was reinforced with only carbon fibers, and the same tests as above were conducted, and the results are shown in Table 2.

[0024]

[Table 2]

[0025]

[Example 3] Si with an average particle size of 1 μm as a matrix
C powder is mixed with a small amount of Al2O3 powder, then kneaded with acrylamide resin, and coated on a woven fabric of SiC fibers to form a SiC/C powder made of SiC fibers and SiC powder.
A SiC composite sheet ■ was obtained. Next, C powder with an average particle size of 1 μm was used as a matrix, and a small amount of Al2 was added to it.
After mixing the O3 powder, it was kneaded with an acrylamide resin and applied onto a carbon fiber woven fabric to obtain a C/C composite sheet (2) consisting of carbon fibers and C powder.

[0026] These composite sheets ■ and ■ are combined to form a set of three SiC/SiC composite sheets ■ (3 sheets in total).
- 3 sets of 2 SiC/SiC composite sheets + 1 C/C composite sheet (9 total) - 3 sets of 1 SiC/SiC composite sheet + 1 C/C composite sheet ( 6 sheets in total) - SiC/SiC composite sheet ■ 1 sheet + C/C composite sheet ■ 3 sets of 2 sheets (9 sheets in total) - C/C composite sheet ■
A total of 30 sheets were laminated in the order of three sheets (total of three sheets). The C/C composite sheet side (■) of the two laminates obtained in this way were stacked together and treated in the same manner as in Example 1. ~SiC composite material (C~SiC/C~SiC composite material) was obtained.

When the thermal expansion coefficient in the plane direction of this C~SiC/C~SiC composite material was measured, it was found that both SiC/S
The iC surface area was 4.4 x 10-6K-1. next,
This C~SiC/C~SiC composite material is used as a base material, and as in Example 1, SiC is applied to both SiC/SiC surfaces of the base material.
was coated to a thickness of approximately 500 μm.

Coatings C to S of the invention produced as described above
For iC/C~SiC composite materials, room temperature and 1500
The bending strength at ℃ was measured. Further, thermal cycles from room temperature to 1700° C. were repeated 10 times in the air, and the room temperature strength after the thermal cycles was measured and the state of the SiC coating layer was observed. The results are shown in Table 3.

As a comparative example, the SiC matrix was
A coated SiC/SiC composite material in which a SiC coating layer is formed on both surfaces of a base material reinforced only with C fibers, and a coated SiC/SiC composite material in which a SiC coating layer is formed on both surfaces of a base material reinforced only with carbon fibers.
A coated C/SiC composite material provided with a coating layer was manufactured and tested in the same manner as above, and the results are shown in Table 3.

[0030]

[Table 3]

[0031]

Effects of the Invention According to the present invention, the coated fiber-reinforced gradient function exhibits excellent strength even at high temperatures of 1500°C or higher and has an SiC coating layer that does not peel or break even under thermal cycles. We can provide materials. This coated fiber-reinforced functionally graded material is most suitable as airframe insulation material used in ultra-high-speed flying vehicles such as spacecraft, scramjet engine material, etc.

Claims (2)

[Claims] Claim 1: Fibers containing carbon fibers and ceramic fibers as reinforcing materials in a matrix consisting of carbon, or at least one of carbides, nitrides, or carbonitrides of elements of group 4A of the periodic table, silicon, or boron. It consists of a reinforced composite material base material and a silicon carbide coating layer provided on both surfaces of the base material, the reinforcement material on both surfaces of the base material is ceramic fiber, the reinforcement material in the center is carbon fiber, and the intermediate material is made of ceramic fiber. The reinforcing material in this part is made of both carbon fiber and ceramic fiber, and the carbon fiber content in the reinforcing material changes almost continuously from 100% in the center to 0% on both surfaces. Coated fiber-reinforced functionally graded material. 2. Fibers containing carbon fibers and ceramic fibers as reinforcing materials in a matrix consisting of carbon, or at least one of carbides, nitrides, or carbonitrides of elements of group 4A of the periodic table, silicon, or boron. Consisting of a reinforced composite material base material and a silicon carbide coating layer provided on one surface of the base material, the reinforcement material on one surface portion of the base material is ceramic fiber, and the reinforcement material on the other surface portion is carbon. The fibers and the reinforcing material in the middle are made of both carbon fiber and ceramic fiber, and the carbon fiber content in the reinforcing material is 0% on one surface.
1. A coated fiber-reinforced functionally graded material characterized by an almost continuous change from 100% to 100% at the other surface.