JPH06107468A - Carbonaceous compound fiber-reinforced ceramic composite material - Google Patents

Abstract

PURPOSE:To improve the strength and toughness of the composite material by using a carbonaceous blend fiber as the reinforcement and an oxide/base nanocompound of the carbide particles and/or nitride particles as the matrix. CONSTITUTION:A carbonaceous compound fiber composed of (A) crystalline carbon oriented in the axial direction of fiber, (B) amorphous carbon and/or crystalline carbon oriented in the direction different from the axial direction of fiber and (C) a silicon-contg. component consisting of silicon, carbon and oxygen is used as the reinforcement, and an oxide-base nanocompound of the carbide particles and/or nitride particles is used as the matrix to produce the composite material. In this case, a chopped fiber or the powder of the oxide-base nanocompound is mixed when the carbonaceous compound fiber is chopped. When the carbonaceous compound fiber is used in the form of sheet, the compound fiber and the powder of the oxide-base nanocomposite are alternately laminated to prepare a laminate. The portion of the carbonaceous compound fiber in the composite material is controlled to 1-70vol.%, and heating and sintering are usually carried out at 400-2500 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-based composite fiber-reinforced ceramic composite material having high strength, high toughness, and high heat resistance. The ceramic composite material of the present invention is used as a member of a turbine engine such as a rotor, a stator or a combustor, a member of a rocket engine such as a nose cone or a nozzle, a member of an internal combustion engine such as a piston head, an auxiliary combustion chamber or a valve. , Can be preferably used.

[0002]

2. Description of the Related Art Oxide ceramics such as aluminum oxide are excellent in heat resistance, but their use as engineering ceramics has been limited because of their low toughness and insufficient strength. . Recently, attempts have been actively made to improve strength and toughness by compounding oxide ceramics with various reinforcing materials.

For example, "Pro.23rd.Autom
ot. Technol. Dev. Contract C
oord. Meet. In 1986, there are 20
By compounding volume% silicon carbide whiskers,
Bending strength is improved from about 300MPa to about 700MPa, and the critical stress intensity factor (K _1C ) is a measure of fracture toughness.
Is 4.5 MPa · m ^1/2 to about 8.5 MPa · m
It is disclosed that it is improved to ^1/2 . However, the bending strength of this whisker-reinforced alumina composite material sharply decreases when it exceeds 1000 ° C. "The Survey of New Materials for Aircraft" issued by the Japan Aerospace Industry Association in March 1998, page 193 shows that for materials for gas turbine rotors, etc., at temperatures in the range of 1250 ° C to 1450 ° C. It is described that the bending strength needs to be 450 MPa or more. The above-mentioned whisker reinforced alumina composite material cannot satisfy the properties required for the above gas turbine member.

A method of improving the strength or heat resistance of oxide ceramics by nanocompositing is also known.
For example, in “Powder and powder alloys”, Vol. 37, p. 348 (1990), a ceramic nanocomposite material prepared by adding 5% by volume of silicon carbide ultrafine particles to aluminum oxide has a heat resistance temperature of 1200 ° C. and bending. Strength about 155
It is disclosed that it exhibits an excellent property of 0 MPa. However, the K _{1C of} this composite material is approximately 4.8 MPa
m ^1/2 , which is lower than about 6 MPa · m ^1/2 which is K _1C of ordinary monolithic silicon nitride.

[0005]

The object of the present invention is to exhibit excellent strength and high fracture toughness value from room temperature to high temperature, which can be suitably used for various heat engines including automobile engines. It is to provide a ceramic composite material. The above object of the present invention is (1) crystalline carbon oriented in the fiber axis direction, (2) amorphous carbon and / or crystalline carbon oriented in a direction different from the fiber axis direction, and (3) silicon. Reinforcement of carbon-based composite fiber using carbon-based composite fiber composed of silicon-containing components composed of carbon and oxygen as a reinforcing material and oxide-based nanocomposite nanocomposited with carbide particles and / or nitride particles as a matrix Achieved by a ceramic composite material.

The above silicon-containing component (3) is (i) an amorphous substance composed of silicon, carbon and oxygen, and (ii) β-S.
An aggregate of crystalline fine particles of iC and C and amorphous SiO ₂ , and (iii) the amorphous substance of (i) above and (i)
It is composed of a mixture with the aggregate of i). The proportion of each element of the silicon-containing component is generally 30 to 70% by weight of Si,
C: 20 to 60% by weight, and O: 0.5 to 10% by weight. In addition to these elements, the above-mentioned silicon-containing component can contain a metal element selected from titanium, zirconium, and hafnium (hereinafter referred to as “M”). In this case, the silicon-containing component is (iv) an amorphous substance composed of silicon, carbon, M, and oxygen, or (v) β-SiC, MC,
A solid solution of C, β-SiC and MC, and at least one kind of crystalline fine particles selected from the group consisting of MC _1-x , and an aggregate composed of amorphous SiO ₂ and MO ₂ (where x is 0 to 0). It is a number less than 1), or (vi) is composed of a mixture of the amorphous substance of (iv) and the aggregate of (v). The ratio of each element is usually Si: 5 to 70
% By weight, C: 20-40% by weight, M: 0.5-45% by weight, O: 0.01-30% by weight.

In the carbon-based composite fiber of the present invention, the ratio of the constituents is such that the weight ratio of constituent (1) to the sum of constituent (2) and constituent (3) is 1: 0.5 to 500.
It is preferable that the ratio is 0 and the weight ratio of the constituent component (2) to the constituent component (3) is 1: 0.02 to 4. The carbon-based composite fiber is disclosed in, for example, JP-A-3-104926.
It can be prepared according to the method described in JP-A-2-229218. The descriptions of these publications are incorporated as part of the present specification. An example of the method for producing the carbon-based composite fiber is shown below. First, a reaction product obtained by reacting an organosilicon polymer such as polycarbosilane with an optically isotropic pitch at a temperature of 250 to 500 ° C. is mixed with a halide of M, an alkoxide or a chelate compound to obtain 100 ~ 500
The reaction product is reacted at a temperature of 300C, and then the reaction product is heated and melted at a temperature of 300 to 500C with a mesophase phase, a premesophase phase or a latent anisotropic pitch. In the obtained heated melt, at least a part of the organosilicon polymer is chemically bonded to the pitch. Then, the heated melt is spun, the spun fiber is infusibilized, and the infusibilized fiber is fired at a temperature of 800 to 3000 ° C. in a vacuum or in an inert gas atmosphere to produce a carbon-based composite fiber. .

The form of the carbon-based composite fiber is not particularly limited, and it may be a chopped fiber, a plain weave woven from continuous fibers, a satin weave, a multiaxial weave, a three-dimensional woven fabric or a non-woven fabric. It may be a sheet-like material obtained by aligning in one direction.

In the oxide-based nanocomposite used as a matrix in the present invention, at least one kind of dispersed particles of carbide particles and nitride particles is intragranular nanocomposite, intergranular nanocomposite or intragranular nanocomposite with oxide ceramics. And a ceramic composed of a nanocomposite structure of both grain boundaries.
The intragranular nanocomposite structure is, for example, a structure in which dispersed particles of nano-order are dispersed in the matrix particles of the oxide-based ceramic to form a composite of the matrix particles themselves, as in the model shown in FIG. On the other hand, the grain boundary nano-composite structure is a structure in which dispersed particles of the nano order are dispersed in the grain boundary of the matrix phase of the oxide-based ceramic, for example, as in the model shown in FIG. Such an oxide-based nanocomposite material is disclosed, for example, in "Journal of the Ceramic Society of Japan" Vol. 99, 9
It can be prepared according to the method described on pages 47-982 (1991).

Specific examples of the oxide-based ceramics that form the matrix phase in the oxide-based nanocomposite material include aluminum,
Magnesium, silicon, yttrium, indium, uranium, calcium, scandium, tantalum, niobium,
Neodymium, lanthanum, ruthenium, rhodium, beryllium, titanium, tin, strontium, barium, zinc,
Mention may be made of oxides of elements such as zirconium and iron, and complex oxides of these metals. The particle size of these oxide-based ceramics is generally 0.05 to 1000 μm.
Is.

Specific examples of the nitride that becomes the dispersed particles include:
Examples thereof include nitrides of elements such as silicon, boron, aluminum, magnesium, titanium, and molybdenum, composite nitrides of these elements, and sialon. Specific examples of the carbide of the dispersed particles include carbides of elements such as silicon, titanium, zirconium, aluminum, uranium, tungsten, tantalum, hafnium, boron, iron and manganese, and composite carbides of these elements. There is no particular limitation on the shape of the dispersed particles in the oxide-based nanocomposite material, and spherical, polyhedral, plate-shaped,
It may be needle-shaped. In the case of spherical or polyhedral particles, the size of dispersed particles is generally 1 to 100 in terms of equivalent diameter.
In the case of a plate or needle, the maximum length or thickness is 10,000 nm. The proportion of dispersed particles in the oxide-based nanocomposite is generally 1 to 50% by volume with respect to the composite.

The carbon-based composite fiber-reinforced ceramic composite material of the present invention can be prepared by blending the carbon-based composite fiber and the oxide-based nanocomposite material according to a method known per se and sintering. When the carbon-based composite fiber is a chopped material, a mixture is prepared by mixing the chopped fiber and the oxide-based nanocomposite powder. When the carbon-based composite fiber is a long fiber, a woven fabric, a non-woven fabric, or a sheet-like material, a laminate is prepared by alternately laminating layers composed of these and layers composed of oxide-based nanocomposite powder. . Then, the carbon-based composite fiber-reinforced ceramics composite material of the present invention can be obtained by heating and sintering the above mixture or laminate into a desired shape or at the same time as forming. The ratio of the carbon-based composite fiber in the composite material is usually 1 to 70% by volume.

As a method for molding the above mixture or laminate, a method known per se, for example, a die pressing method, a rubber pressing method, an extrusion method or a sheet method can be adopted. Known organic polymers such as polyvinyl alcohol, polyethylene oxide and aluminum alkoxide, as well as polycarbosilane and polymetallocarbosilane can be used as the binder during molding.
There is also no particular limitation on the sintering method, and a method known per se such as a method of sintering a molded article under normal pressure or reduced pressure, a hot pressing method or a hot isostatic pressing method of simultaneously performing molding and sintering. Can be adopted. The heating and sintering temperature is usually 400 to 2500 ° C. If the heating and sintering temperature is too low, the oxide nanocomposite that is the matrix will not be sufficiently sintered, and if the temperature is too high, the carbon-based composite fiber will be decomposed.

As another method for preparing the carbon-based composite fiber-reinforced ceramic composite material of the present invention, instead of using the oxide-based nanocomposite powder itself as the raw material powder for the matrix, a raw material for the oxide-based nanocomposite material is used. A method similar to the above can also be adopted, except that a mixed powder obtained by mixing a powder of oxide-based ceramics and a particle of carbide and / or nitride by a known method is used. In this case, during the molding and sintering process, the nanocomposite of the matrix and the composite of the matrix and the carbon-based composite fiber occur simultaneously or sequentially to prepare the carbon-based composite fiber-reinforced ceramic composite material of the present invention. It

[0015]

EXAMPLES Examples of the present invention will be shown below. Reference Example 1 Among petroleum fractions, high-boiling substances of light oil or higher were subjected to fluid catalytic cracking / rectification at a temperature of 500 ° C. in the presence of a silica / alumina cracking catalyst to obtain a residue from the bottom of the column. Hereinafter, this residue is referred to as "FCC slurry oil". The FCC slurry oil was heated to 450 ° C under a nitrogen gas stream, the distillate at the same temperature was distilled off, and the residue was filtered while hot at 200 ° C to remove the infusible portion at the same temperature to obtain pitch A. It was Pitch A was subjected to polycondensation at 400 ° C. for 7 hours in a nitrogen stream while removing the light components produced by the reaction to obtain pitch B.

Reference Example 2 Polydimethylsilane synthesized by dechlorinating and condensing dimethyldichlorosilane with sodium metal was heat-treated at 420 ° C. with stirring under a nitrogen stream to give a number average molecular weight of 12
00 organosilicon polymer was obtained.

Reference Example 3 21 g of the organosilicon polymer obtained in Reference Example 2 and 20 ml of xylene were added to 49 g of the pitch A obtained in Reference Example 1, the temperature was raised with stirring, and xylene was distilled off.
And reacted for 6 hours to obtain 39 g of a precursor polymer. To 39 g of this precursor polymer, a xylene solution of 2.75 g of tetraoctoxytitanium (11 g of 25% xylene solution) was added, and after distilling off xylene, the mixture was reacted at 340 ° C. for 2 hours to obtain 38 g of a random copolymer. 35 g of this random copolymer and 70 g of the pitch B obtained in Reference Example 1 were mixed and melt-heated at 310 ° C. for 1 hour under a nitrogen atmosphere to obtain a polycyclic aromatic polymer containing silicon and titanium in a uniform state. Got united. This polycyclic aromatic polymer was melt-spun, and the spun fiber was infusibilized by thermal oxidation at 300 ° C. in air. The infusible fiber was fired at 1300 ° C. in an argon atmosphere to obtain a carbon-based composite fiber. This carbon-based composite fiber has a fiber diameter of 10μ.
m, tensile strength 3.1 GPa, tensile elastic modulus 320 GPa
(The measurement is based on the single fiber test method.).

Reference Example 4 γ-alumina having an average particle size of 0.5 μm has an average particle size of 0.3 μm.
5% by volume of β-silicon carbide particles of m were added, and the particles were added to 12 in ethanol by a ball mill using alumina balls.
Wet mixed for hours. Then, the mixture was dried, and the powder obtained by dry-mixing for 12 hours was further dried in a nitrogen gas atmosphere.
Hot-pressing was performed in a graphite die at a pressure of 30 MPa and a temperature of 1500 to 1800 ° C. to obtain an alumina-based nanocomposite material (SiC particles / Al ₂ O ₃ nanocomposite material) reinforced with silicon carbide particles. The bending strength of this nanocomposite at room temperature is 1.
5 GPa and K _1C were 5 MPa · m ^1/2 , and the maximum operating temperature was 1200 ° C.

Reference Example 5 Magnesia having an average particle size of 0.1 μm has an average particle size of 0.3 μm.
The following silicon carbide particles were added in an amount of 10% by volume, and a silicon nitride ball was used in a ball mill for 24 hours in toluene.
After wet mixing for an hour, the mixture was dried. The mixed powder was placed in a nitrogen gas atmosphere at a pressure of 28 MPa and 1700 to
Hot-pressed in a graphite die at a temperature of 1900 ° C and reinforced with silicon carbide particles magnesia nanocomposite (SiC
Granules / MgO nanocomposite) was obtained. The bending strength of this nanocomposite at room temperature is 700 MPa, and K _1C is 4 MPa · m.
^1/2 , the maximum operating temperature was 1300 ° C.

Example 1 The SiC particles / Al ₂ O ₃ nanocomposite material obtained in Reference Example 4 was crushed in distilled water for 30 hours by a ball mill using a silicon nitride ball and a silicon nitride pot to form a nanocomposite. A slurry of material was obtained. Polyethylene oxide as a binder was added to the slurry in an amount of 10% by weight based on the nanocomposite material, and the mixture was wet-mixed for 12 hours using a silicon nitride ball to obtain a matrix raw material slurry. The bundle of carbon-based composite fibers obtained in Reference Example 3 was opened by air blowing and then dipped in the slurry of the matrix raw material described above to attach matrix powder around each carbon-based composite fiber. After winding the bundle of carbon-based composite fibers to which the matrix powder is attached to a square drum,
It was sufficiently dried to prepare a prepreg sheet. After cutting this prepreg sheet into a desired shape, it is laminated in a graphite die coated with boron nitride as a release agent, and hot-pressed at a temperature of 1650 ° C. and a pressure of 65 MPa in an argon gas atmosphere to obtain SiC particles / A carbon-based composite fiber-reinforced ceramics composite material using an Al ₂ O ₃ nanocomposite material as a matrix was obtained. The ratio of carbon-based composite fiber in the composite material is 5
It was 5% by volume. The flexural strength of this composite material was 1.93 GPa at room temperature and 1.8 GPa at 1300 ° C.
The fracture toughness value (K _1C ) of the composite material measured by the chevron notch method was 21.5 MPa · m ^1/2 .

Example 2 γ-alumina having an average particle size of 0.4 μm has an average particle size of 0.3 μm.
5% by volume of α-silicon nitride particles of m was added, and alumina balls were used in a ball mill to make 16
The mixed powder which was wet-mixed for an hour, sufficiently dried, and further dry-mixed for 10 hours was used as a raw material powder for the matrix. A sheet of the carbon-based composite fiber obtained by opening the carbon-based composite fiber bundle obtained in Reference Example 3 by blowing it into the air and the above Matrix raw material powder were treated with boron nitride as a release agent. Alternately laminated in coated graphite dies, in argon gas atmosphere, temperature of 1600 ° C, 75M
Hot pressing was performed at Pa to obtain a carbon-based composite fiber-reinforced ceramic composite material having a SiC grain / Al ₂ O ₃ nanocomposite as a matrix. The ratio of the carbon-based composite fiber in the composite material was 40% by volume. The flexural strength of this composite material was 1.71 GPa at room temperature and 1.82 GPa at 1300 ° C. The fracture toughness value (K _1C ) of the composite material measured by the chevron notch method was 16.4 MPa · m ^1/2 .

Example 3 The SiC particles / MgO nanocomposite material obtained in Reference Example 5 was mixed with a ball mill using a ball made of silicon nitride and a pot made of silicon nitride at a volume ratio of ethanol and distilled water of 4: 1. A nanocomposite slurry was prepared by grinding in a solvent for 30 hours. Polyethylene oxide as a binder was added to this slurry in an amount of 10% by weight with respect to the nanocomposite material, and then wet-mixed for 12 hours using a silicon nitride ball to obtain a matrix raw material slurry. In the same manner as in Example 1, the carbon-based composite fiber was opened, the matrix raw material was attached to the carbon-based composite fiber, wound, and dried to prepare a prepreg sheet. This prepreg sheet was cut into a desired shape, laminated, and then degreased. After applying boron nitride as a release agent to this laminate and vacuum-sealing it in a glass capsule, hot isostatic pressing was performed in argon gas at a temperature of 1850 ° C. and a pressure of 150 MPa to obtain SiC grains / MgO nano particles. A carbon-based composite fiber-reinforced ceramics composite material using the composite material as a matrix was obtained. The ratio of carbon-based composite fiber in this composite material was 45% by volume. The flexural strength of this composite material was 1.57 GPa at room temperature and 1.54 GPa at 1300 ° C. The fracture toughness value (K _1C ) of the composite material measured by the chevron notch method was 19.4 MPa · m ^1/2 .

Example 4 The carbon-based composite fiber obtained in Reference Example 3 was cut into a chopped fiber by cutting it to a length of 1 to 2 mm. The chopped fibers were dispersed in ethanol using ultrasonic waves and an omni mixer together. The matrix raw material slurry prepared in Example 3 was added to the dispersion liquid, and the mixture was wet-mixed for 5 hours by a ball mill using nylon balls. 1m thick with chopped fibers uniformly dispersed from this mixed slurry by filtration
A m-thick prepreg sheet was prepared. After cutting this prepreg sheet into a desired shape, the prepreg sheet is laminated in a graphite die coated with boron nitride as a release agent, and hot-pressed at a temperature of 1850 ° C. and a pressure of 75 MPa in an argon gas atmosphere to obtain SiC. A carbon-based composite fiber-reinforced ceramics composite material having a grain / MgO nanocomposite material as a matrix was obtained. The ratio of the carbon-based composite fiber in the composite material was 30% by volume. The flexural strength of this composite material was 0.85 GPa at room temperature and 0.82 GPa at 1300 ° C. The fracture toughness value (K _1C ) of the composite material measured by the chevron notch method was 9.8 MPa · m ^1/2 .

[0024]

[Brief description of drawings]

FIG. 1 is a model of intragranular nanocomposite.

FIG. 2 is a model of a grain boundary nanocomposite material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiko Sato 5 1978, Ogushi, Ube, Yamaguchi Prefecture 5 1978, Inorganic Materials Laboratory, Ube Industries Ltd. (72) Inventor Makoto Tamura 5 1978, Ogushi, Ube, Yamaguchi Prefecture 5 Ube Kosan Inorganic Materials Research Center

Claims (1)

[Claims] 1. A crystalline carbon oriented in a fiber axis direction,
(2) Amorphous carbon and / or crystalline carbon oriented in a direction different from the fiber axis direction, and (3) a carbon-based composite fiber composed of a silicon-containing component composed of silicon, carbon and oxygen is used as a reinforcing material. , Using an oxide-based nanocomposite nanocomposited with carbide particles and / or nitride particles as a matrix,
Carbon composite fiber reinforced ceramic composite material.