JP2756685B2 - Method for producing composite material and raw material composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a matrix (mother phase) using at least one kind of ceramics among oxides, nitrides, and nitrided oxides.
The present invention relates to a method for producing a ceramic composite material in which a carbide of an element from Groups IVa to VIa of the periodic table or a solid solution of nitrogen and oxygen in the carbide is dispersed and strengthened, and a raw material composition thereof. Things.

[Conventional technology]

Alumina, mullite, sialon, silicon nitride and other oxides, nitride oxides, and nitride ceramics are typical structural ceramics, and are excellent in hardness, strength, corrosion resistance, etc., and are therefore used in machine parts, tools, refractories, etc. Used for a wide range of applications. By adding carbide particles of elements from Groups IVa to VIa of the periodic table to these materials, fracture toughness and hardness can be increased. For example, there is a composite material in which TiC particles are blended in a ceramic matrix containing alumina as a main component, which has excellent characteristics as an initial tool (Japanese Patent Publication No. 60-54266). Also, a composite material has been developed in which carbide particles of Group IVa to VIa elements are blended in a matrix of ceramics containing silicon nitride or sialon as a main component (Japanese Patent Publication No. Sho 62-53475).

As a method for producing these composite materials, a matrix material such as alumina and a carbide of a group IVa to VIa element or a solid solution of nitrogen or oxygen or the like in the carbide (carbonitride, carbonate, etc.) And a sintering agent added as necessary, and then pressure sintering or normal pressure sintering. However, this manufacturing method has the following disadvantages.

(1) Particles of commercially available carbides of Group IVa to VIa elements and powders obtained by dissolving nitrogen, oxygen or the like in the carbides (carbonitrides, carbonates) generally have a large particle size and exceed 10 μm. Such coarse particles are also mixed. When the carbide of the metal element is dispersed in the composite material, coarse particles tend to be a starting point of fracture, which causes a reduction in strength.

(2) In recent years, with the development of grinding technology,
m, fine metal carbides below m are now available, but coarse particles are still mixed in, and these fine powders are expensive, contain a large amount of impurities such as Fe, and react with water. High in nature. For this reason, water cannot be used as a mixing medium at the time of mixing the raw materials, and it is difficult to keep powder characteristics constant, and a composite material using such a fine metal carbide as a raw material is Variations in characteristics increase.

[Description of First Invention] The first invention (the invention described in claim (1)) has been made in view of the problems of the above-described conventional technology, and has poor characteristics and is difficult to handle. It is an object of the present invention to provide a method capable of producing a composite material of a ceramic in which these carbides are dispersed without using a carbide of a group VIa element or a solid solution of nitrogen or oxygen in the carbide as a raw material. is there.

In the first invention, at least one ceramic selected from oxides, nitrides, and nitrided oxides is used as a matrix, and in the matrix, at least one carbide selected from Group IVa to VIa elements, or / A method for producing a composite material comprising at least one carbide selected from the group consisting of elements from groups IVa to VIa of the periodic table in which nitrogen and / or oxygen is dissolved as a solid solution, comprising: A raw material of at least one kind of ceramics of nitrogen oxides, the ceramic itself, a substance that forms the ceramics by sintering excluding simple metals, or a raw material that is a precursor of the ceramics; Mixing an oxide containing at least one of Group IVa to VIa elements and / or a precursor of the oxide with carbon or / and an organic substance that generates carbon by thermal decomposition Preparing a raw material composition by Rukoto a method of producing a composite material characterized by comprising the step of firing the raw material composition.

According to the first invention, as a raw material, a carbide of a group IVa to VIa element or a group IVa to a solid solution of nitrogen or oxygen is used.
It is possible to provide a method capable of manufacturing a composite material in which the carbide is dispersed without using a carbide of a VIa group element.

That is, in the first aspect of the present invention, at the stage of firing the raw material composition, at least one oxide of the above Group IVa to VIa group elements in the raw material composition and / or a precursor of the oxide Reacting with carbon or / and an organic substance which forms carbon by thermal decomposition to form an oxide of at least one of the above-mentioned Group IVa to VIa elements and / or the above-mentioned carbide in which nitrogen or oxygen is dissolved. It is to produce a composite material in which the carbide is dispersed.

The oxides are generally inexpensive and high purity submicron powders are readily available. In addition, since high-purity fine oxide particles can be obtained from the precursor of the oxide by thermal decomposition or the like, the generated carbide also has fine and high purity.

Therefore, the composite material manufactured according to the first invention is
Since the particle diameter of the carbide particles dispersed therein is small, the strength is high and the characteristics such as fracture toughness and strength are stable.

Further, since the above-mentioned carbide is not used as a raw material, water can be used at the time of mixing the raw material composition, and a composite material having a small variation in the characteristics of the sintered body can be manufactured.

[Description of Second Invention] The second invention (the invention described in claim (2)) is the first invention.
An object of the present invention is to provide a raw material composition that can be used in the production method of the present invention.

The second invention provides, as a matrix, at least one ceramic selected from the group consisting of oxides, nitrides, and nitrided oxides, wherein the matrix contains at least one of the elements of Groups IVa to VIa of the periodic table. Carbide, or / and nitrogen or /
And a material composition of a composite material in which at least one carbide of Group IVa to VIa elements of the periodic table in which oxygen forms a solid solution is dispersed, comprising oxide, nitride, and oxynitride. A raw material of ceramics consisting of at least one of the following materials, a raw material of the ceramics itself, a substance that forms the ceramics by sintering excluding a simple metal, or a raw material of a precursor of the ceramics, It is prepared by mixing an oxide containing at least one of the elements from IVa to VIa or / and a precursor of the oxide with carbon and / or an organic substance that generates carbon by pyrolysis. A raw material composition for a composite material, comprising:

According to the second invention, a raw material composition that can be used in the production method of the first invention can be provided.

[Description of Other Inventions of First and Second Inventions] Hereinafter, other inventions that make the first and second inventions more specific will be described.

The raw material composition used in the present invention comprises a ceramic raw material comprising at least one of an oxide, a nitride, and a nitride oxide, and a Group IVa element (titanium, zirconium, hafnium), Va group elements (vanadium, niobium,
An oxide containing at least one of tantalum) or Group VIa elements (chromium, molybdenum, tungsten) and / or a precursor of the oxide (hereinafter referred to as a metal oxide) and carbon or / and It is a mixture of an organic substance that generates carbon by thermal decomposition. The raw material composition is desirably used in the form of a powder for producing a composite material.

In the present invention, the raw material for ceramics made of at least one of oxides, nitrides, and nitrided oxides becomes a matrix by a method for producing a composite material. As the oxide, alumina (Al ₂ O ₃ ), silica (Si
O ₂ ), mullite (3Al ₂ O ₃ · 2SiO ₂ ), yttria (Y
₂ O ₃ ), calcium oxide (CaO), magnesium oxide (Mg
O), stomium oxide (SrO ₂ ), titania (TiO ₂ ),
Examples include chromium oxide (Cr ₂ O ₃ ) and oxides of rare earth elements, and at least one of them is used. Examples of the nitride include silicon nitride (Si ₃ N ₄ ) and aluminum nitride (AlN), and at least one of them is used. Examples of the nitric oxide include aluminum oxynitride, silicon oxynitride, various types of α- or β-sialon, and at least one of them is used. The raw material of these ceramics is ceramics itself, a substance that forms the ceramics by sintering excluding simple metals, or a precursor substance of the ceramics. For example, substances that generate Al ₂ O ₃ by firing include Al (OH) ₃ , AlOOH, and aluminum alkoxide. The precursor material of Si ₃ N ₄ is Si (NH)
₂ , Si ₂ N ₃ H and the like.

Raw materials for the ceramic include a sintering aid or Y
Additives such as ₂ O ₃ and ZrO ₂ which contribute to improvement in high-temperature strength or fracture toughness may be added.

As the metal oxide, TiO, TiO ₂ , Ti ₂ O ₃ , ZrO, Z
rO ₂ , HfO ₂ , VO, VO ₂ , V ₂ O ₃ , V ₂ O ₅ , NbO, NbO ₂ , Nb ₂ O ₅ ,
Oxides such as Ta ₂ O ₅ , Cr ₂ O ₃ , MoO ₂ , MoO ₃ , WO ₂ , WO ₃ or solid solutions between metal oxides, compounds between the above metal oxides such as TiZrO ₄ , ZrW ₂ O ₈ (Double oxide), ZrSiO ₄ (zircon)
And the like (compound oxide with SiO ₂ ) or a solid solution of the above metal oxide and a silicon compound, such as Al ₂ TiO ₅ , and a compound of an aluminum compound (a double oxide with Al ₂ O ₃ ) Or a solid solution, a precursor such as a hydroxide salt, an alkoxide, or an organic substance which is decomposed by heating to become the above-mentioned metal oxide. At least one of these is used. The form of these substances may be particulate, fibrous, or liquid.

Here, during the production process, the metal oxide reacts with carbon (in the case of using an organic substance that generates carbon by thermal decomposition, carbon), and is dispersed in the composite material by the carbon oxide.
It is to be at least one type of carbide of the group IVa to VIa element (hereinafter referred to as metal carbide). When the metal oxide is in the form of particles or liquid, the resulting metal carbide is in the form of particles. Further, if the metal oxide is in the form of particles and there is no agglomeration during the production process, one metal oxide particle often produces one metal carbide particle. Therefore, when a fine metal oxide is used, a fine metal carbide is generated. When the oxide turns into a carbide, there are some which expand in volume and some which contract. However, usually, the particle size does not change significantly even if it shrinks a little, and when a submicron metal oxide is formed from a submicron metal oxide and a metal carbide of 0.5 μm or less is formed from a metal oxide of 0.5 μm or less. Conceivable.

Further, when the metal oxide is fibrous, if the fiber is not damaged during the manufacturing process, it becomes a fibrous metal carbide of almost the same size.

Further, the shape of the generated metal carbide may be a particle shape, a fibrous shape, or a mixture thereof. In the case of particles, the average particle size is preferably 1 μm or less, and when such fine particles are dispersed,
Extremely high strength. More preferably, the average particle size is 0.5 μm
It is better to do the following. However, the strength of the composite material is higher in the fibrous state than in the equiaxial state.

Examples of carbon or an organic substance that generates carbon by thermal decomposition include carbon blacks, a phenol resin, a tar pitch, and a furan resin, and at least one of them is used.

When a metal oxide or carbon and / or an organic substance that generates carbon by thermal decomposition is used in a powder state, a finer and less agglomerated material is preferable because it has better reactivity and can synthesize a finer metal carbide.

The metal oxide and carbon react with each other in the firing step in producing the composite material to form a metal carbide, and the carbide is precipitated and dispersed in the composite material.

As metal carbide, TiC, ZrC, HfC, VC, Nb ₂ C, Nb
C, Ta ₂ C, TaC, Cr ₃ C ₂ , Mo ₂ C, MoC, W ₂ C, WC, etc., and at least one of these. In addition, any of these shows a high effect of improving fracture toughness when dispersed and precipitated in ceramics composed of at least one of oxides, nitrides, and nitrided oxides. In general, the transition metal carbide does not always exist in the above stoichiometric composition, but shows a wide solid solution range. For example, TiC, Z
rC and the like generally exist in the chemical formulas TiC _1-a and ZrC _1-a (0 ≦ a <1). Even these solid solutions have a sufficiently high effect.

If the metal oxide is MO _x and the metal carbide is MC _y (x and y are positive numbers), the reaction between MO _x and carbon to produce MC _y is expressed as MO _x + (x + y) C → It is expressed by MC _y + xCO ↑. Therefore, in this case, (x + y) moles of carbon are required for 1 mole of the metal element M. For example, TiO ₂
When producing a composite material in which TiC is precipitated by using as a raw material, the reaction formula is TiO ₂ + 3C → TiC + 2CO ↑, and the ratio of TiO ₂ / C required for the reaction is 1/3 in molar ratio, weight The ratio is 79.9 / 36.0.

However, the above reaction usually becomes MC _y via MO and M (C, O). (In the above reaction for producing a composite material on which TiC is deposited, it passes through TiO, Ti (C, O). To become TiC.) Therefore, when the amount of carbon or an organic substance that generates carbon by thermal decomposition is small in the raw material composition, the composite material is formed in the form of a carbide (carbon oxide) in which oxygen is dissolved, for example, M (C, O). May be dispersed. In the case of firing in a nitrogen atmosphere, nitrogen may be dispersed in the composite material in the form of a solid solution of carbon (carbonitride), for example, M (C, N). Carbides of these oxygen or nitrogen in a solid solution also similar cubic crystal form and MC _x property is very close to the MC _x, has the same excellent properties composites these carbides are dispersed.

The mixing ratio of the metal oxide and carbon or / and the organic substance which becomes carbon by thermal decomposition is such that the metal carbide produced by the reaction of the two substances is a matrix: metal carbide in the composite material finally produced. = 95: 5 to 50:50 (volume ratio) is desirable. When the amount of the carbide is smaller than the above range, the effect of improving the toughness is hardly observed, and when the amount of the metal carbide is larger than the above range, the oxidation resistance at high temperatures decreases.

For example, in the case of Si ₃ N ₄ containing a sintering aid as a matrix, to make the above ratio Si ₃ N ₄ : metal carbide = 95: 5 to 50:50 (volume ratio), metal oxide and carbon or The ratio of the organic substance that becomes carbon by thermal decomposition is preferably as follows.

For example, when manufacturing a composite material in which MO _x is used as a metal oxide and MC _y is dispersed as a metal carbide, the molecular weight of MO _x is M ¹ , the molecular weight of MC _y is M ² , and the density of MC _x is d _c Assuming that the density of the Si ₃ N ₄ sintered body is 3.25 g / cm ³ , the Si ₃ N ₄
100 metal oxide with respect to weight parts (in terms of oxide in the case of the precursor of the oxides) ^{_{are, 1.62d c · M 1 / M}} 2 ~30.8d c · M
¹ / M ² parts by weight, carbon or / and organic substances as a carbon by pyrolysis in terms of carbon _{19.4d c (x + y) /} M 2 ~369
It is desirable to mix within the range of d _c (x + y) / M ² parts by weight.

As a method for preparing the raw material composition of the present invention, the above composition is obtained by mixing a ceramic raw material serving as a matrix, a metal oxide, and carbon or / and an organic substance that generates carbon by thermal decomposition. There is a way.

The composition may be mixed by a dry method or a wet method, but a wet method is preferable because a sufficiently uniform mixture can be formed. In the case of a wet method, the mixed medium may be water or an organic solvent, and drying may be performed by any drying method such as spray drying, freeze drying, and suction filtration.
The drying is performed in a vacuum, an inert atmosphere, an oxidizing atmosphere,
Any of a reducing atmosphere may be used. However, when an organic substance is used as a raw material, the mixed medium may be limited to an organic solvent. Also, when using a sintering aid which easily reacts with water such as AlN, it is preferable to use an organic solvent.

In cases other than the above, since the powder can be mixed with water and dried in the atmosphere, a large amount of powder can be treated by a spray dryer not of a normal type, that is, a non-explosion-proof type.

When carbon powder is added, the dispersibility of the carbon powder can be improved by adding a small amount of a surfactant during wet mixing.

When a molded article of a composite material is produced, the raw material composition is preferably molded before firing.

The molding can be performed by any method commonly used for molding ceramics, for example, slip casting, injection molding, extrusion molding, mold molding, hydrostatic molding,
Wide application such as wet press molding and doctor blade.

In the firing step, the raw material composition is preferably fired in a vacuum or a non-oxidizing atmosphere. The reason why the atmosphere is made vacuum or non-oxidizing is to rapidly produce a composite material without oxidizing non-oxides in the raw material composition. Even more desirable is a method of heating in a vacuum until a metal oxide is formed, followed by firing in a nitrogen or inert atmosphere. In particular, when the matrix contains nitrides or oxynitrides, in order to prevent thermal decomposition of these substances, it is necessary to heat in a vacuum until metal carbides are formed, and then fire in a nitrogen atmosphere of 1 atm or more. Good.

The firing temperature is preferably selected from the range of 1500 to 2000 ° C. As the sintering method, any method such as normal pressure sintering or pressure sintering such as hot pressing can be used, but usually, pressure sintering is easier to obtain a high-density composite material. . In the case of normal pressure sintering, in order to prevent thermal decomposition of the matrix, it is preferable to arrange the matrix material as a so-called filling powder around the material composition and fire it.
When hot pressing is performed, molding and firing can be performed simultaneously.

The metal oxide reacts with the carbon in the middle of the firing to form a metal carbide, which is dispersed and precipitated in the matrix.

In the case of a reaction in which the rate of the carbide formation reaction is low, the formation reaction occurs, and desirably, the matrix is not thermally decomposed, and is maintained at a temperature lower than the temperature at which the densification greatly proceeds, and the carbide formation is performed. After the reaction is completed, the temperature is preferably raised again. At this time, if the generated CO gas is removed by vacuum evacuation during the holding, the reaction proceeds even faster.
For example, Si ₃ N ₄ containing 5% Al ₂ O ₃ and 5% Y ₂ O ₃ , TiO ₂ ,
In the case of producing a composite material in which 20% by volume of TiC is dispersed and precipitated in a Si ₃ N ₄ sintered body using
It is desirable to hold for more than 2 hours while evacuating at a temperature of ~ 1400 ° C. After performing such a vacuum holding, raise the temperature again in N ₂ gas and complete the firing at 1600 to 2000 ° C. Thereby, a high-density composite material can be obtained. If the vacuum holding time is insufficient, the composite material has a low relative density.

The conditions for carrying out the intermediate holding at the temperature during the firing differ depending on the type of the reaction system, the amount of gas generation, the structure of the furnace, particularly the ease with which the generated gas is evacuated, and the like.

Also, hot isostatic pressing (HIP) molding can be used as a sintering method. In one of the sintering HIPs, a sintered body that has been subjected to normal pressure sintering or hot pressing and densified until almost or all of the open pores have disappeared is further increased to 1700.
The density and strength can be further increased by applying hydrostatic pressure in a non-oxidizing atmosphere at a temperature range of 22200 ° C. Hydrostatic pressure is effective if 10MPa or more, but 50M
It is desirable to apply a pressure of Pa or more. Also capsule
In HIP, after the formed body is heat-treated in advance to complete the metal carbide formation reaction, the formed body is vacuum-sealed in a glass capsule and subjected to HIP processing (glass capsule method). After performing the treatment (glass bath method), apply the glass powder to the surface of the molded body, and then sinter the applied layer by heating to convert it to an airtight seal layer.
Processing (sintered glass method), a method in which a molded body is embedded in glass powder, heated, and uniaxially pressed to form a hermetic seal layer, followed by HIP processing (press seal method), etc. HIP under the same conditions as the sintering HIP method
By processing, a dense composite material is obtained.

In this way, metal carbide particles are formed and precipitated by the reaction between the metal oxide and carbon in the first stage of firing, and the matrix is densified in the second stage.

In addition, the residual carbon may be present in the sintered body in addition to the matrix and the metal carbide, but if the amount is small, the characteristics are not impaired.

When a fibrous substance is used as the metal oxide of the raw material composition, care should be taken to minimize fiber breakage during mixing, molding, or firing under pressure. For example, when performing hot pressing, it is preferable to gradually pressurize after metal carbide is generated.

The composite material produced according to the present invention has cracks (cracks, cracks) due to metal carbides precipitated during the progress of the cracks.
(Deflection) and branching (crack branching) occur, consuming a large amount of fracture energy, thereby realizing a high fracture toughness value. In addition, the metal carbide is fine and hardly serves as a fracture starting point, and does not cause a decrease in strength.

〔Example〕

 Hereinafter, embodiments of the present invention will be described.

Example 1 Table 1 shows Al ₂ O ₃ powder (α type average particle size 0.1 μm), TiO ₂ powder (rutile type average particle size 0.4 μm) and carbon black powder (average particle size 0.02 μm). So, Ti
The molar ratio of O ₂ and C of carbon black is 1: 3, and the volume ratio of Al ₂ O ₃ and TiC synthesized by stoichiometric reaction of TiO ₂ and C is (Al ₂ 90:10, 80:20, 7 for O ₃ : TiC)
The mixture was weighed so as to reach 0:30, and mixed by a wet pole mill using water to form a slurry. This slurry was suction-filtered, dried and crushed to obtain a raw material composition.

Put this in a black smoke die with graphite tape inside, raise the temperature while evacuating without pressurizing, 1300 ℃
For 6 hours to obtain a molded body. Thereafter, the exhaust was stopped, Ar gas was introduced into the furnace, the temperature was raised again, and a uniaxial pressurization of 25 MPa was applied to the compact, followed by hot pressing at 1700 ° C.
For 1 hour to complete hot pressing to produce a composite material (Samples Nos. 1 to 3 in Table 1).

Also, for comparison, as shown in Table 1, only Al ₂ O ₃ was used as a raw material composition (sample No. C1) or Al ₂ O ₃ was used.
A mixture of TiC powder (average particle size: 4 μm) and a raw material composition (sample No. C2) was hot-pressed in the same manner as above to produce a sample.

The relative density, room temperature four-point bending strength (JIS standard), and fracture toughness (K _IC , indentation method) of the above sample were measured. Table 1 shows the results.

The composite material of this example was obtained by X-ray diffraction using α-Al ₂ O ₃ and T
It was confirmed that the film was composed only of iC and was composed of TiC dispersed in α-Al ₂ O ₃ . As is clear from Table 1, all of the composite materials of this example have a relative density of 99% or more, and have higher strength and K _IC than the sample No. C1 of the comparative example. Further, it is found that the sample has higher density and strength than the sample No. C2 of the comparative example.

In Samples Nos. 2 and 3, the electrical resistivity was 0.1 Ωcm or less, and wire cutting and engraving could be easily performed by electric discharge machining.

Example 2 Si ₃ N ₄ powder (α type, average particle diameter 0.5 μm), Y ₂ O ₃ powder (average particle diameter 0.7 μm), and AlN powder (average particle diameter 1 μm) were in a molar ratio of 83: 1.7. The material weighed at a ratio of 15.3 was used as a matrix raw material. To become When this hot pressing at 1,750-1,850 ° C. Density The 3.22~3.23g / cm ^3, consider the theoretical density of the matrix formed from the raw material of the matrix and 3.23 g / cm ^3, and the matrix material, TiO _Two powders (rutile type, average particle size 0.4 μm) and a phenol resin (residual carbon ratio: 50%) were weighed as follows. The weighed value is determined by the volume ratio (matrix: Ti) of the matrix and TiC synthesized by the stoichiometric reaction of TiO ₂ and carbon generated by thermal decomposition from the phenol resin at a molar ratio of 1: 3.
C) was adjusted to 90:10, 80:20, 70:30. These were mixed by a wet ball mill using ethyl alcohol to form a slurry. This slurry was absorbed, filtered, dried and crushed to obtain a raw material composition. This was placed in a graphite die with graphite tape affixed to the inside, heated without evacuation and evacuated, and kept at 1200 ° C. for 8 hours to obtain a molded body. After that, stop evacuation, introduce N ₂ gas into the furnace, raise the temperature again, apply uniaxial pressure of 25MPa to the molded body, hot press it, hold at 1800 ° C for 1 hour and complete the hot press To produce composite materials (Sample Nos. 4 to 6 in Table 1).

For comparison, as shown in Table 1, only the raw material of the matrix was mixed with alcohol, filtered, dried, and crushed to obtain a raw material composition (sample No. C).
3) Alternatively, a mixture obtained by adding a TiC powder (average particle size: 2 μm) to the raw material of the matrix as a raw material composition (sample No. C4) was hot-pressed in the same manner as above to produce a sample.

For the above sample, relative density, room temperature 4-point bending strength,
And K _IC were measured in the same manner as in Example 1. Table 2 shows the results.

Composite material of the present embodiment, α'-Si ₃ N ₄ and (Y is dissolved α- sialon) β'-Si ₃ N ₄ and (beta-sialon) T
It was confirmed that TiC was dispersed in the matrix consisting of α′-Si ₃ N ₄ and β′-Si ₃ N ₄ . Also, as is clear from Table 1, the composite material of this embodiment has a high strength and K _IC than sample No.C3 comparative example, also, higher than the sample No.C2 of Comparative Example It can be seen that it has density and strength.

In addition, electrical discharge machining was easily performed on Samples Nos. 5 and 6.

Example 3 Mullite powder (average particle diameter 0.8 μm) or β-sialon powder (average particle diameter 0.8 μm) was used as a raw material of a matrix, respectively, and TiO _{2 was used in the same} manner as in Example 1.
A carbon black powder, a matrix formed from the matrix raw material, and TiC, which is synthesized by stoichiometric reaction of the TiO ₂ and carbon black powder, have a volume ratio (matrix: TiC) of 80: It was weighed to 20 and mixed with water in the same manner as in Example 1 to prepare a raw material composition. Thereafter, the raw material composition was hot-pressed in the same manner as in Example 1 to produce composite materials (Sample Nos. 7 and 8). However, the hot pressing conditions are as follows: when mullite is used as the raw material for the matrix, pot press in Ar gas at 1750 ° C for 1 hour, and when using sialon as the raw material for the matrix, the gas introduced after vacuum holding must be used.
And N _2, and a condition for 1 hour hot pressed at 1800 ° C..

Further, for comparison, a material composition using only mullite powder as a raw material composition (Sample No. C5) and a material composition using only sialon powder as a raw material composition (Sample No. C6) were used in an Ar atmosphere, respectively.
_A sample was produced by hot pressing in the same manner as above in _two atmospheres.

For the above sample, relative density, room temperature 4-point bending strength,
And K _IC were measured in the same manner as in Example 1. The results are shown in Tables 3 and 4.

The composite material of Sample No. 7 is composed of a mullite matrix and oxygen-dissolved TiC due to the presence of a mullite matrix peak and a slightly shifted TiC peak toward TiO in X-ray diffraction. The above TiC in the matrix
Was found to be dispersed. Further, in the composite material of Sample No. 8, the β-sialon matrix and nitrogen were dissolved in solid form by the presence of the β-sialon matrix peak and the TiC peak slightly shifted toward TiN in X-ray diffraction. It consisted of TiC, and it was confirmed that the TiC was dispersed in the matrix. Further, Table 3, As is apparent from Table 4, the composite material of the present embodiment is seen to have a high strength and K _IC than that of Comparative Example.

Example 4 Al ₂ O ₃ or Si ₃ N ₄ (α-type average particle size 0.5 μm): Al ₂ O ₃ (α-type average particle size 0.1 μm): Y ₂ O ₃ (average particle size) similar to that of Example 1 A mixed powder of (0.7 μm) = 90: 5: 5 (weight ratio) was used as a raw material for the matrix, and the TiO ₂ powder and the carbon black powder used in Example 1 were mixed with the matrix formed by the raw material for the matrix. TiO ₂ and carbon black are added so that the volume ratio (matrix: TiC) of TiC generated by stoichiometric reaction is 85:15, mixed with water using a ball mill, and dried with a spray dryer And
A raw material composition was prepared. This raw material composition was subjected to die molding at a pressure of 20 MPa, and then subjected to a hydrostatic pressure molding treatment of 300 MPa. Each of the compacts was placed in a filling powder of a matrix material, heated in vacuum, and kept at 1250 ° C. for 8 hours. afterwards,
For Al ₂ O ₃ matrix sample, Ar gas was introduced into the furnace, and Ar1
Under the condition of 1680 ° C. 3 hours in the air pressure, sample the Si ₃ N ₄ matrix N ₂ gas was introduced into the furnace, and pressureless sintering under conditions of N ₂ 10.5 atm in 1750 ° C. 4 h.

The resulting composite material, Al ₂ O ₃ in the sample of the matrix, from that there is a peak of slightly offset TiC towards the peak and TiO of α-Al ₂ O ₃ in the X-ray diffraction, alpha-Al ₂ O ₃
And TiC in which oxygen was dissolved, and it was confirmed that α-Al ₃ O ₃ was used as a matrix, and the TiC was dispersed in a matrix. Further, in the sample of the Si ₃ N ₄ matrix, the β′-Si ₃ N ₄ peak and the TiC peak slightly shifted toward TiN in the X-ray diffraction indicate that β ′
-Si ₃ N ₄ and TiC in which nitrogen is dissolved, and β′-Si ₃ N
₄ was used as a matrix, and it was confirmed that the TiC was dispersed in the matrix. The relative density of the composite material was 97.4% for the Al ₂ O ₃ matrix sample and 99.0% for the Si ₂ N ₄ matrix sample (Si ₃ N ₄ without TiC).
The theoretical density of the sintered body was 3.25 g / cm ³ . ).

Example 5 The raw material powder of the Si ₃ N ₄ matrix used in Example 4 was used as the raw material of the matrix, and ZrO ₂ (monoclinic type average particle diameter 1 μm) and carbon black powder (average particle diameter 0.02 μm)
m) The powder formed from the raw materials of the matrix and the ZrC synthesized by the stoichiometric reaction of ZrO ₂ and C have a volume ratio (matrix: ZrC) of 80:20. Was added. Further, the raw material powder of the same the Si ₃ N ₄ matrix as a raw material of the matrix, to which Nb ₂ O
₅ (average particle size 0.6 μm), carbon black (average particle size
02 μm), a matrix formed from the raw material of the matrix and NbC synthesized by stoichiometric reaction of Nb ₂ O ₅ and C at a volume ratio (matrix: NbC) of 80:20.
Was added so that These two raw material compositions were mixed, dried, crushed and hot pressed in the same manner as in Example 1. However, the gas to be introduced into the furnace after holding halfway was N ₂ gas, and hot pressing was performed under N ₂ 1 atm.
Performed at 0 ° C. for 1 hour.

The resulting composite material, with ZrO ₂ added, has a β ′
-Si ₃ N ₄ and ZrC, it was confirmed that β′-Si ₃ N ₄ was used as a matrix, and ZrC was dispersed in the matrix. In the case where NbO ₂ is added, β′-Si ₃ N
₄ and NbO ₂ , with β′-Si ₃ N ₄ as a matrix,
It was confirmed that Nb was dispersed in the matrix. The relative density was 97.8% with ZrO ₂ added.
%, And 99.8% when NbO ₂ was added.

Continuation of front page (56) References JP-A-52-104515 (JP, A) JP-A-62-235258 (JP, A) JP-A-62-256773 (JP, A) JP-A-62-256767 (JP, A) JP-A-62-288166 (JP, A) JP-A-62-288165 (JP, A) JP-A-63-85048 (JP, A) JP-A-63-89457 (JP, A)

Claims (2)

(57) [Claims] 1. A ceramic comprising at least one of oxides, nitrides and nitride oxides as a matrix, wherein said matrix contains at least one element selected from the group IVa to VIa of the periodic table. A method for producing a composite material comprising at least one carbide selected from the group consisting of elements of Groups IVa to VIa of the Periodic Table, in which carbides or / and nitrogen and / or oxygen are dissolved as solids, Raw material of ceramics made of at least one of a material, a nitride, and a nitride oxide, the raw material being the ceramic itself, a substance that forms the ceramic by firing except for a simple metal, or a precursor substance of the ceramic And an oxide containing at least one of the elements from Groups IVa to VIa of the Synchronous Table or / and a precursor of the oxide; and carbon or / and carbon by thermal decomposition. Method for producing a composite material comprising the steps of: preparing a raw material composition by mixing the organic material to be generated, characterized by comprising the step of firing the raw material composition. 2. A matrix comprising at least one of oxides, nitrides and nitride oxides as a matrix, wherein the matrix contains at least one of the elements of Groups IVa to VIa of the periodic table. A raw material composition for a composite material in which at least one of carbides or / and nitrogen or / and oxygen is dissolved as a solid solution and at least one of Group IVa to VIa group elements of the periodic table is dispersed, It is a raw material for ceramics composed of at least one of oxides, nitrides, and nitric oxides, and is composed of the ceramics itself, a substance that forms the ceramics by firing except for a single metal, or a precursor substance of the ceramics. A raw material, an oxide containing at least one of the elements of Groups IVa to VIa of the periodic table or / and a precursor of the oxide, and carbon or / and Raw material composition of the composite material characterized in that it is prepared by mixing an organic substance which produces.