JP2004067481A - High heat resistance inorganic fiber bonded ceramics and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a thick shape article of high heat resistance inorganic fiber bonded ceramics having stable quality, an excellent heat resistance and smoothness. <P>SOLUTION: The thick shape article is formed by hot pressing a preform consisting of (A) and (B) or (C) and (D) integrated with a laminate of (A) the inorganic fiber bonded ceramics mainly consisting of a sintered structure of SiC and boundary layers essentially consisting of the inorganic fibers containing specific metal atoms and carbon and (B) the inorganic fibers containing specific metal atoms or a laminate of (C) the inorganic fiber bonded ceramics consisting of the inorganic fibers mainly composed of Si, M, C and O and boundary layers essentially consisting of inorganic materials and C, and (D) the inorganic fibers of which the inside surface layers are composed of the assemblage of an amorphous material consisting of Si, M, C, and O, crystalline superfine particles of β-SiC, MC and C and amorphous materials of SiO<SB>2</SB>and MO<SB>2</SB>and of which the surface layers are composed of an amorphous material consisting of Si and O and crystalline materials of crystalline SiO<SB>2</SB>and MO<SB>2</SB>. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thick-walled high-heat-resistant inorganic fiber-bonded ceramic that can be used in a region requiring extremely high heat resistance of 1200 ° C. or higher, and a method for producing the same. In particular, a thick high-temperature member that cannot be manufactured by a single hot press manufacturing, and has high surface smoothness and denseness, and is required to have high fracture resistance, for example, for power generation or aircraft It can be applied to high temperature members of gas turbines for industrial use.
[0002]
[Prior art]
Simple ceramic materials, such as silicon carbide and silicon nitride, are expected to be used as high-efficiency gas turbine components because of their excellent strength at high temperatures of 1300 ° C or higher, but they are inherent disadvantages of simple ceramics. It is fragile and very susceptible to internal small pores or cracks, and thus has poor reliability. In particular, in the case of large objects, a considerable safety factor must be expected in consideration of the size effect. Therefore, since a thick member made of a single ceramic having high heat resistance and high strength has low reliability, a large-sized high-temperature material such as a thick member having high heat resistance and high reliability is desired.
[0003]
On the other hand, a carbon fiber reinforced carbon matrix composite material (hereinafter, referred to as C / C composite material) and a ceramic fiber reinforced ceramic matrix composite material (hereinafter, referred to as CMC) have the above-mentioned brittleness of a single ceramic. It is a high-toughness material that has been improved without deteriorating high-temperature characteristics, and has been actively studied as a high-temperature material. Since these various composite materials are manufactured by a chemical vapor deposition method (CVD method), a chemical osmosis gas phase method (CVI method), or a polymer impregnation method (PIP method), tens of percent of voids are produced. It remains.
Therefore, when machining is performed, voids appear on the surface to impair the surface smoothness. Therefore, it is necessary to develop a high toughness and high heat resistant composite material having excellent surface smoothness and heat resistance.
[0004]
The fiber-bonded ceramic is a high-temperature material with high heat resistance, high toughness, and high density that overcomes the above-mentioned disadvantages of the simple ceramic and the composite material. However, since fiber-bonded ceramics are manufactured using a hot press apparatus, there is a limit to the wall thickness that can be manufactured due to restrictions on the volume of the apparatus and the moving distance of the press ram. In addition, when the thickest shape that can be manufactured is manufactured, there may be a difference in mechanical characteristics between the surface portion and the inside depending on the performance of the apparatus (heating range, heating rate, etc.). Therefore, it is desired to produce a thick-walled fiber-bonded ceramic having a stable quality.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a thick-walled high-heat-resistant inorganic fiber-bonded ceramic having a stable quality and excellent heat resistance and smoothness, and a method for producing the same, and have a high surface smoothness and extremely high surface roughness. The present invention can be applied to a thick member requiring heat resistance and high breaking resistance, for example, a high temperature member such as a power generation or a gas turbine for an aircraft.
[0006]
[Means for Solving the Problems]
According to the present invention,
(A) An inorganic fiber mainly composed of a sintered structure of SiC, wherein 0.01 to 1% by weight of O and at least one metal selected from the group consisting of metal atoms of groups 2A, 3A and 3B An inorganic fiber-bonded ceramic in which atoms-containing inorganic fibers are bonded in a structure very close to close-packed, and a boundary layer containing 1 to 100 nm of C as a main component is formed between the fibers. A thick inorganic fiber-bonded ceramic characterized by having a thickness in the laminating direction of more than 19 mm.
According to the present invention,
(A) An inorganic fiber mainly composed of a sintered structure of SiC, wherein 0.01 to 1% by weight of O and at least one metal selected from the group consisting of metal atoms of groups 2A, 3A and 3B An inorganic fiber-bonded ceramics in which the inorganic fibers containing atoms are bonded in a structure very close to the closest packing, and between the fibers, a boundary layer mainly composed of 1 to 100 nm of C is formed;
(B) (a) polysilane having a molar ratio of carbon atoms to silicon atoms of 1.5 or more, or a heat-reacted product thereof, containing at least one selected from the group consisting of metal elements of groups 2A, 3A and 3B; (B) melt-spinning of a metal element-containing organosilicon polymer to obtain spun fibers; (c) spinning the spun fibers in an oxygen-containing atmosphere. A laminate of infusible fibers obtained by a third step of preparing infusible fibers by heating at -170 ° C., or (d) a fourth step of mineralizing the infusible fibers in an inert gas. With a laminate of mineralized fibers,
The integrated preform formed of (A) and (B) is set in a carbon die and placed in a carbon die in an atmosphere of at least one selected from the group consisting of vacuum, an inert gas, a reducing gas, and a hydrocarbon. A method for producing a thick-walled inorganic fiber-bonded ceramics, characterized by performing hot pressing at a temperature in the range of ２2200 ° C. under a pressure of 100 to 1000 kg / cm ² .
[0007]
Furthermore, according to the present invention,
(C) (i) an inorganic fiber comprising the following (a) and / or (b):
(A) an amorphous substance composed of Si, M, C and O (M represents Ti or Zr),
(B) (1) an aggregate of β-SiC, MC and C crystalline fine particles, and ( ₂ ) an amorphous substance of SiO ₂ and MO ₂ ,
(Ii) an inorganic material which fills the gaps between the inorganic fibers and comprises the following (c) and / or (d), and optionally (e) is dispersed:
(C) an amorphous material consisting of Si and O, optionally M;
(D) a crystalline substance comprising crystalline SiO ₂ and MO ₂ ,
(E) a crystalline fine particle inorganic material composed of MC having a particle size of 100 nm or less,
(Iii) a boundary layer of 1 to 100 nm in which crystalline particles composed of MC and having a particle diameter of 100 nm or less in some cases are formed on the surface of the inorganic fiber and are dispersed.
And a thick-walled inorganic fiber-bonded ceramic characterized by having a thickness in the laminating direction of the fibers of more than 65 mm.
According to the present invention,
(C) (i) an inorganic fiber comprising the following (a) and / or (b):
(A) an amorphous substance composed of Si, M, C and O (M represents Ti or Zr),
(B) (1) an aggregate of β-SiC, MC and C crystalline fine particles, and ( ₂ ) an amorphous substance of SiO ₂ and MO ₂ ,
(Ii) an inorganic material which fills the gaps between the inorganic fibers and comprises the following (c) and / or (d), and optionally (e) is dispersed:
(C) an amorphous material consisting of Si and O, optionally M;
(D) a crystalline substance comprising crystalline SiO ₂ and MO ₂ ,
(E) a crystalline fine particle inorganic material composed of MC having a particle size of 100 nm or less,
(Iii) a boundary layer of 1 to 100 nm in which crystalline particles composed of MC and having a particle diameter of 100 nm or less in some cases are formed on the surface of the inorganic fiber and are dispersed.
An inorganic fiber-bound ceramic composed of:
(D) An inorganic fiber comprising an inner surface layer and a surface layer, wherein the inner surface layer comprises:
(A) an amorphous substance composed of Si, M, C and O (M represents Ti or Zr);
(B) an aggregate of crystalline ultrafine particles of β-SiC, MC and C and an amorphous substance of SiO ₂ and MO ₂ , or (c) an amorphous substance of (a) and (b) Composed of an inorganic substance containing a mixture with an aggregate of the surface layer,
(D) an amorphous material comprising Si and O, optionally M;
(E) a crystalline substance composed of crystalline SiO ₂ and / or MO ₂ , or (f) an inorganic substance containing a mixture of the amorphous substance (d) and the crystalline substance (e). And the thickness T (unit μm) of the surface layer is T = aD (where a is a numerical value in the range of 0.023 to 0.053, and D is the diameter (unit μm) of the inorganic fiber. And a laminate of inorganic fibers that satisfies
The integrated preform formed of (C) and (D) was set in a carbon die and hot-pressed in an inert gas atmosphere at a temperature in the range of 1500 to 2000 ° C. and a pressure of 100 to 1000 kg / cm ^2. The present invention provides a method for producing a thick-walled inorganic fiber-bonded ceramic, which is characterized by being treated.
[0008]
In the present invention, a thick-walled article of two types of inorganic fiber-bonded ceramics ((A) and (C)), which could not be produced conventionally, is produced by using the two types of inorganic fiber-bonded ceramics and the same. A method for producing a thick-walled highly heat-resistant inorganic fiber-bonded ceramic by integrating a laminate ((B) and (D)) composed of two types of inorganic fibers, which is a raw material at the time, is proposed. .
First, a thick-walled inorganic fiber-bound ceramic according to claims 1 and 2 and a method for producing the same will be described.
[0009]
The fiber material constituting the inorganic fiber-bound ceramics (A) is an inorganic fiber mainly composed of a sintered structure of SiC, 0.01 to 1% by weight of O, and metal atoms of groups 2A, 3A and 3B. Contains at least one metal atom selected from the group consisting of: and is bonded to a structure very close to close packing.
The inorganic fiber having a sintered structure of SiC mainly has a polycrystalline sintered structure of β-SiC, or further, is composed of crystalline fine particles of β-SiC and C. In a region in which β-SiC crystal particles containing microcrystals of C and / or a trace amount of O and sintered without passing through the second phase of the grain boundary, a strong bond between the SiC crystals is obtained. Even if the fracture occurs in the inorganic fiber, it progresses in the SiC crystal grains in a region of at least 30% or more. In some cases, intergranular fracture regions and intragranular fracture regions between SiC crystals are mixed.
[0010]
The fibrous material contains at least one metal atom selected from the group consisting of group 2A, group 3A and group 3B metal elements. The ratio of the elements constituting the fiber material is usually 55 to 70% by weight of Si, 30 to 45% by weight of C, 0.01 to 1% by weight of O, M (2A group, 3A group and 3B group metal). Element): 0.05 to 4.0% by weight, preferably 0.1 to 2.0% by weight. Among the metal elements of the 2A group, the 3A group and the 3B group, Be, Mg, Y, Ce, B and Al are particularly preferable, and these are all known as sintering aids for SiC, There are chelate compounds and alkoxide compounds that can react with the Si—H bond of the silicon polymer. If the proportion of the metal is too small, sufficient crystallinity of the fiber material cannot be obtained, and if the proportion is too high, the intergranular fracture will increase and the mechanical properties will decrease.
[0011]
At the boundaries between the fiber materials of the inorganic fiber-bonded ceramics (A), an amorphous and crystalline carbon is formed with a boundary layer having a thickness of 1 to 100 nm, preferably 10 to 50 nm, Reflecting the structure shown above, it is excellent in fracture toughness and dense, and maintains almost room temperature strength even at 1600 ° C.
[0012]
The thick-walled inorganic fiber-bonded ceramic (A) of the present invention has a thickness in the laminating direction of the fibers of more than 19 mm.
This thick-walled inorganic fiber-bonded ceramic is obtained by mixing the inorganic fiber-bonded ceramic (A) having a thickness of 19 mm or less manufactured by a conventional method with a laminate (B) made of raw fibers used in manufacturing the ceramic. The preform formed of (A) and (B), in which is integrated, is set in a carbon die, and in a vacuum, an atmosphere of at least one selected from the group consisting of an inert gas, a reducing gas, and a hydrocarbon, It is manufactured by hot pressing at a temperature in the range of 1700-2200 ° C. and a pressure of 100-1000 kg / cm ² .
[0013]
The laminate (B) is manufactured by the following procedure.
First, (a) a polysilane having a molar ratio of carbon atoms to silicon atoms of 1.5 or more or a heat-reacted product thereof contains at least one member selected from the group consisting of metal elements of groups 2A, 3A and 3B. A first step of preparing a metal element-containing organosilicon polymer of (b), a second step of melt-spinning the metal element-containing organosilicon polymer to obtain a spun fiber, and (c) spinning the spun fiber in an oxygen-containing atmosphere at 50 to 50%. It comprises a third step of preparing infusible fibers by heating at 170 ° C. and (d) a fourth step of mineralizing the infusible fibers in an inert gas.
[0014]
First Step In the first step, a metal-containing organosilicon polymer as a precursor polymer is prepared.
Polysilane is a chain or cyclic polymer obtained by subjecting one or more dichlorosilanes to a dechlorination reaction using sodium according to the method described in, for example, "Chemistry of Organosilicon Compounds", Kagaku Dojin (1972). And has a number average molecular weight of usually 300 to 1,000. The polysilane in the present invention may have a hydrogen atom, a lower alkyl group, a phenyl group or a silyl group as a silicon side chain, and in any case, the molar ratio of carbon atoms to silicon atoms is 1.5. It is necessary to be above. If this condition is not satisfied, all of the carbon in the fiber will be desorbed as carbon dioxide in the process of raising the temperature until sintering, together with oxygen introduced during infusibilization, and a boundary carbon layer between fibers will not be formed. It is not preferred.
[0015]
The polysilane in the present invention includes an organosilicon polymer obtained by heating the above-mentioned chain or cyclic polysilane and partially containing a carbosilane bond in addition to the polysilane bond unit. Such an organosilicon combination can be prepared by a method known per se. Examples of the preparation method include a method in which a chain or cyclic polysilane is heated and reacted at a relatively high temperature of 400 to 700 ° C., and a method in which a phenyl group-containing polyborosiloxane is added to the polysilane and a relatively low temperature of 250 to 500 ° C. And a heat reaction method. The number average molecular weight of the organosilicon polymer thus obtained is usually from 1,000 to 5,000.
[0016]
The phenyl-containing polyborosiloxane can be prepared according to the methods described in JP-A-53-42300 and JP-A-53-50299. For example, a phenyl-containing polyborosiloxane can be prepared by a dehydrochlorination condensation reaction between boric acid and one or more diorganochlorosilanes, and the number average molecular weight is usually 500 to 10,000. The amount of the phenyl group-containing polyborosiloxane is usually 15 parts by weight or less based on 100 parts by weight of the polysilane.
[0017]
A predetermined amount of a compound containing a metal element belonging to the group 2A, 3A or 3B is added to the polysilane and reacted in an inert gas at a temperature usually in the range of 250 to 350 ° C. for 1 to 10 hours. In addition, a metal element-containing organosilicon polymer as a raw material can be prepared. The metal element is used in such a proportion that the content of the metal element in the finally obtained sintered SiC fiber composite is 0.05 to 4.0% by weight, and the specific proportion is determined according to the teachings of the present invention. The trader can determine it appropriately.
The above-mentioned organosilicon polymer containing a metal element is a crosslinked polymer having a structure in which at least a part of silicon atoms of polysilane is bonded to a metal atom via or not via an oxygen atom.
[0018]
As the compound containing a metal element belonging to the group 2A, 3A or 3B added in the first step, an alkoxide, an acetylacetoxide compound, a carbonyl compound, a cyclopentadienyl compound or the like of the metal element can be used. Examples thereof include beryllium acetylacetonate, magnesium acetylacetonate, yttrium acetylacetonate, cerium acetylacetonate, butyric borate, and aluminum acetylacetonate.
All of these have a structure in which each metal element is bonded to Si directly or via another element by reacting with a Si—H bond in an organosilicon polymer generated upon reaction with polysilane or a heated reactant thereof. Can be generated.
[0019]
Second step In the second step, a spun fiber of a metal element-containing organosilicon polymer is obtained.
A spun fiber can be obtained by spinning a metal element-containing organosilicon polymer as a precursor polymer by a method known per se such as melt spinning and dry spinning.
[0020]
Third Step In the third step, the infusible fiber is prepared by heating the spun fiber at 50 to 170 ° C. in an oxygen-containing atmosphere.
The purpose of infusibilization is to form a bridging point by oxygen atoms between the polymers constituting the spun fibers so that the infusibilized fibers do not melt and the adjacent fibers do not fuse together in the subsequent mineralization step. It is to be.
As the gas constituting the oxygen-containing atmosphere, the infusibilization time depends on the infusibilization temperature, but is usually several minutes to 30 hours.
It is desirable to control the content of oxygen in the infusibilized fiber so as to be 8 to 16% by weight. Most of this oxygen remains in the fiber even after mineralization in the next step, and plays an important role in desorbing excess carbon in the inorganic fiber as CO gas during the temperature rise process until final sintering. I do.
If the oxygen content is less than 8% by weight, excess carbon in the inorganic fibers remains more than necessary and segregates around the SiC crystal during the heating process to stabilize the β-SiC crystal. When the content is more than 16% by weight, excess carbon in the inorganic fibers is completely eliminated, and a boundary carbon layer between the fibers is not generated. All of these adversely affect the mechanical properties of the resulting material.
[0021]
It is preferable that the infusible fiber is further preheated in an inert atmosphere.
Examples of the gas constituting the inert atmosphere include nitrogen and argon. The heating temperature is usually 150 to 800 ° C., and the heating time is only a few minutes to 20 hours. By preheating the infusibilized fiber in an inert atmosphere, while preventing the incorporation of oxygen into the fiber, the crosslinking reaction of the polymer constituting the fiber is further advanced, and the infusibilized fiber from the precursor polymer is converted. The strength can be further improved while maintaining excellent elongation, whereby the mineralization in the next step can be stably performed with good workability.
[0022]
Fourth Step In the fourth step, the infusibilized fiber is heat-treated in an inert gas atmosphere such as argon at a temperature in the range of 1000 to 1700 ° C. in a continuous or batchwise manner to mineralize it.
[0023]
In the present invention, after forming the infusibilized fiber or the mineralized fiber produced by the above procedure into a sheet, a woven or a chop, a laminate (B) comprising at least one of them is produced. .
Next, a preform in which the previously produced inorganic fiber-bonded ceramic (A) and the laminate (B) are integrated is produced. At this time, the method of integration is not particularly limited, and for example, several inorganic fiber-bonded ceramics (A) are prepared in order to produce a thick-shaped product as much as possible. The laminate (B) may be arranged between them.
The preform thus obtained is set on a carbon die, and heated to a temperature of 1700 to 2200 ° C. in an atmosphere consisting of at least one selected from the group consisting of vacuum, inert gas, reducing gas and hydrocarbon. By performing hot pressing under a pressure of 100 to 1000 kg / cm ^{2 in} the range, a thick inorganic fiber-bonded ceramic can be produced.
Note that, in the temperature raising process before pressurization, a pressurization program corresponding to the above-described CO desorption speed may be incorporated.
[0024]
Next, a thick inorganic fiber-bound ceramic according to claims 3 and 4 and a method for producing the same will be described.
Inorganic fiber bonded ceramics (C)
(I) an inorganic fiber comprising the following (a) and / or (b):
(A) an amorphous substance composed of Si, M, C and O (M represents Ti or Zr),
(B) (1) an aggregate of β-SiC, MC and C crystalline fine particles, and ( ₂ ) an amorphous substance of SiO ₂ and MO ₂ ,
(Ii) an inorganic material which fills the gaps between the inorganic fibers and comprises the following (c) and / or (d), and optionally (e) is dispersed:
(C) an amorphous material consisting of Si and O, optionally M;
(D) a crystalline substance comprising crystalline SiO ₂ and MO ₂ ,
(E) a crystalline fine particle inorganic material composed of MC having a particle size of 100 nm or less,
(Iii) a boundary layer of 1 to 100 nm in which crystalline particles composed of MC and having a particle diameter of 100 nm or less in some cases are formed on the surface of the inorganic fiber and are dispersed.
Consists of
[0025]
The inorganic fiber (i) is composed of (a) an amorphous substance composed of Si, M, C and O, and / or (b) (1) crystalline fine particles of β-SiC, MC and C, and (2) SiO ₂ and an aggregate of MO ₂ and an amorphous substance. Β-SiC and MC in the crystalline fine particles can also exist as a solid solution thereof, and MC exists as MC1-x (x is 0 or more and less than 1) in a carbon-deficient state. You can also. The ratio of each element constituting the inorganic fiber is usually 30 to 60% by weight of Si, 0.5 to 35% by weight of M, preferably 1 to 10% by weight, 25 to 40% by weight of C, and 0 to 0%. 0.01 to 30% by weight. The equivalent diameter of the inorganic fiber is generally 5 to 20 μm.
[0026]
The content of the inorganic fiber (i) constituting the inorganic fiber-bound ceramic (C) is 80% by volume or more, preferably 85 to 91% by volume. On the surface of each inorganic fiber, amorphous and crystalline carbon are generated in a non-consistent layered form as a boundary layer in a range of 1 to 100 nm, preferably 10 to 50 nm. In some cases, crystalline particles made of MC having a particle diameter of 100 nm or less are dispersed in the boundary layer. Then, (c) an amorphous substance composed of Si and O and possibly M, and / or (d) a crystalline substance composed of crystalline SiO ₂ and MO ₂ so as to fill the gaps of the inorganic fibers. The substance is present. In some cases, (e) a crystalline fine particle inorganic material composed of MC having a particle diameter of 100 nm or less is dispersed in the inorganic material.
That is, amorphous and / or crystalline carbon is present in a layered manner at the boundaries between inorganic fibers and between the inorganic material and the inorganic fibers in a non-matching manner. The inorganic fiber-bonded ceramic (C) is excellent in fracture toughness and dense, reflecting the above-mentioned structure, and maintains extremely high mechanical properties at 1500 ° C. of 80% or more of room temperature strength. ing.
[0027]
The thick-walled inorganic fiber-bonded ceramic (C) of the present invention has a thickness in the laminating direction of the fibers of more than 65 mm.
This thick-walled inorganic fiber-bonded ceramic is composed of the above-mentioned inorganic fiber-bonded ceramic (C) manufactured by a conventional method and having a thickness of 65 mm or less, and a laminate (D) composed of raw fibers used in manufacturing the ceramic. The preform formed of (C) and (D), in which the components are integrated, is set in a carbon die, and is heated under a pressure of 100 to 1000 kg / cm ² at a temperature in the range of 1500 to 2000 ° C. in an inert gas atmosphere. It is manufactured by pressing.
[0028]
The laminate (D) is manufactured by the following procedure.
The inorganic fiber used as a raw material of the present invention is prepared by heating the inorganic fiber in an oxidizing atmosphere at a temperature in the range of 500 to 1600 ° C., for example, according to the method described in JP-A-62-289641. be able to. This inorganic fiber (M: Ti) is commercially available from Ube Industries, Ltd. as Tyranno Fiber (registered trademark). The form of the inorganic fiber is not particularly limited, and may be a continuous fiber, a chopped short fiber obtained by cutting the continuous fiber, or a sheet-like material or woven fabric obtained by aligning the continuous fiber in one direction.
[0029]
The surface layer of the inorganic fibers is formed by subjecting the above fibers to a heat treatment in an oxidizing atmosphere such as air, pure oxygen, ozone, water vapor, or carbon dioxide. The thickness T (μm) of the surface layer of the inorganic fiber is T = aD (where a is a numerical value in the range of 0.023 to 0.053, and D is the diameter (unit μm) of the inorganic fiber. It is necessary to select heat treatment conditions so as to satisfy.). By strictly controlling the thickness of the surface layer within the above range, it becomes possible to prepare an extremely dense inorganic fiber-bound ceramic having a porosity of 2% or less.
[0030]
By the above-mentioned heat treatment, an inorganic fiber composed of an inner layer and a surface layer, wherein the inner layer is
(A) an amorphous substance composed of Si, M, C and O (M represents Ti or Zr);
(B) an aggregate of crystalline ultrafine particles of β-SiC, MC and C and an amorphous substance of SiO ₂ and MO ₂ , or (c) an amorphous substance of (a) and (b) An inorganic material containing a mixture with an aggregate of (a), wherein the surface layer is composed of (d) an amorphous material comprising Si and O, and optionally M;
(E) a crystalline substance composed of crystalline SiO ₂ and / or MO ₂ , or (f) an inorganic substance containing a mixture of the amorphous substance (d) and the crystalline substance (e). And the thickness T (unit μm) of the surface layer is T = aD (where a is a numerical value in the range of 0.023 to 0.053, and D is the diameter (unit μm) of the inorganic fiber. Is obtained.
Next, a chop-like short fiber obtained by cutting the continuous fiber of the inorganic fiber, or a laminate (D) including at least one shape of a sheet-like material or a woven fabric in which the continuous fibers are aligned in one direction is manufactured.
[0031]
Further, the preformed body is manufactured by integrating the inorganic fiber bonding type ceramic (C) manufactured in advance and the laminate (D). At this time, the method of integration is not particularly limited, and for example, several inorganic fiber-bonded ceramics (C) are prepared in order to produce a thick-shaped product as much as possible. The laminate (D) may be arranged between them.
The pre-formed body thus obtained is set in a carbon die, and hot-pressed in an inert gas atmosphere at a temperature in the range of 1500 to 2000 ° C. under a pressure of 100 to 1000 kg / cm ² , A thick inorganic fiber-bonded ceramic can be manufactured.
[0032]
【Example】
Examples are shown below to explain the present invention in more detail. The mechanical properties of the inorganic fiber-bound ceramics were measured as follows.
[Evaluation of mechanical properties]
The maximum bending strength in the fiber reinforcement direction and the laminating direction was determined by a four-point bending test using an Orientec Tensilon universal testing machine. The shape of the bending test piece in the fiber reinforcement direction was 4 mm in width, 3 mm in height, and 40 mm in length, and the shape of the bending test piece in the laminating direction was 5 mm in width, 3 mm in height, and 15 mm in length. The speed of the crosshead was 0.5 mm / min.
[0033]
Example 1
First, 1 L of dimethyldichlorosilane was added dropwise to anhydrous xylene containing 400 g of sodium while heating and refluxing xylene under a stream of nitrogen gas, followed by reflux for 10 hours to form a precipitate. This precipitate was filtered and washed with methanol and then with water to obtain 420 g of white polydimethylsilane.
Next, 750 g of diphenyldichlorosilane and 124 g of boric acid are heated at 100 to 120 ° C. in n-butyl ether under a nitrogen gas atmosphere, and the resulting white resinous material is further heat-treated at 400 ° C. for 1 hour in vacuum. As a result, 530 g of a phenyl group-containing polyborosiloxane was obtained.
4 parts of the phenyl group-containing polyborosiloxane was added to 100 parts of the polydimethylsilane obtained above, and thermally condensed at 350 ° C. for 5 hours in a nitrogen gas atmosphere to obtain a high molecular weight organosilicon polymer. 7 parts of aluminum-tri- (sec-butoxide) was added to a xylene solution in which 100 parts of the organosilicon polymer was dissolved, and a cross-linking reaction was performed at 310 ° C. under a nitrogen gas stream to synthesize polyaluminocarbosilane. This was melt-spun at 245 ° C., heat-treated in air at 140 ° C. for 5 hours, and further heated in nitrogen at 300 ° C. for 10 hours to obtain infusible fibers. The infusibilized fibers were continuously fired in nitrogen at 1500 ° C. to synthesize silicon carbide continuous inorganic fibers. These fibers were processed into a woven form and laminated to produce two laminates. Then, after one laminate was charged in a carbon die, it was molded at a pressure of 50 MPa and a temperature of 1850 ° C. to obtain an inorganic fiber-bonded ceramic having a thickness of 18 mm. A preform was prepared by laminating the inorganic fiber-bound ceramic and another laminate prepared in advance. After charging the preform in a carbon die, the preform was molded at a pressure of 50 MPa and a temperature of 1850 ° C. to obtain an inorganic fiber-bonded ceramic having a thickness of 36 mm. As shown in FIG. 1, the obtained thick inorganic fiber-bonded ceramic was processed into a predetermined test piece shape and subjected to a four-point bending test. 2 and 3 show bending test results in the fiber direction and the lamination direction, respectively. Specimens cut out from any position had almost the same results. It was possible to produce a thick inorganic fiber-bound ceramic with stable quality.
[Brief description of the drawings]
FIG. 1 is a view showing a cutout position and a direction of a four-point bending test piece from a highly heat-resistant inorganic fiber-bonded ceramic obtained in Example 1 of the present invention.
FIG. 2 is a diagram showing the results of a four-point bending test in the fiber direction of the highly heat-resistant inorganic fiber-bonded ceramics obtained in Example 1 of the present invention.
FIG. 3 is a diagram showing the results of a four-point bending test in the laminating direction of the highly heat-resistant inorganic fiber-bonded ceramics obtained in Example 1 of the present invention.

Claims (4)

(A) An inorganic fiber mainly composed of a sintered structure of SiC, in which 0.01 to 1% by weight of O and at least one metal selected from the group consisting of metal atoms of groups 2A, 3A and 3B An inorganic fiber-bonded ceramic in which atoms-containing inorganic fibers are bonded in a structure very close to close-packed, and a boundary layer containing 1 to 100 nm of C as a main component is formed between the fibers; Characterized by having a thickness in the lamination direction of more than 19 mm. (A) An inorganic fiber mainly composed of a sintered structure of SiC, wherein 0.01 to 1% by weight of O and at least one metal selected from the group consisting of metal atoms of groups 2A, 3A and 3B An inorganic fiber-bonded ceramics in which the inorganic fibers containing atoms are bonded in a structure very close to the closest packing, and between the fibers, a boundary layer mainly composed of 1 to 100 nm of C is formed;
(B) (a) polysilane having a molar ratio of carbon atoms to silicon atoms of 1.5 or more, or a heat-reacted product thereof, containing at least one selected from the group consisting of metal elements of groups 2A, 3A and 3B; (B) melt-spinning of a metal element-containing organosilicon polymer to obtain spun fibers; (c) spinning the spun fibers in an oxygen-containing atmosphere. A laminate of infusible fibers obtained by a third step of preparing infusible fibers by heating at -170 ° C., or (d) a fourth step of mineralizing the infusible fibers in an inert gas. A preform formed of (A) and (B), in which the laminate of the mineralized fibers is integrated, is set in a carbon die, and at least one selected from the group consisting of vacuum, inert gas, reducing gas, and hydrocarbons From one species That in the atmosphere, from 1,700 to 2,200 manufacturing method of ℃ ranging thick shape, characterized by hot pressing under a pressure of 100 to 1000 / cm ² at a temperature inorganic fiber bonding ceramics. (C) (i) an inorganic fiber comprising the following (a) and / or (b):
(A) an amorphous substance composed of Si, M, C and O (M represents Ti or Zr),
(B) (1) an aggregate of β-SiC, MC and C crystalline fine particles, and ( ₂ ) an amorphous substance of SiO ₂ and MO ₂ ,
(Ii) an inorganic material which fills the gaps between the inorganic fibers and comprises the following (c) and / or (d), and optionally (e) is dispersed:
(C) an amorphous material consisting of Si and O, optionally M;
(D) a crystalline substance comprising crystalline SiO ₂ and MO ₂ ,
(E) a crystalline fine particle inorganic material composed of MC having a particle size of 100 nm or less,
(Iii) a boundary layer of 1 to 100 nm in which crystalline particles composed of MC and having a particle diameter of 100 nm or less in some cases are formed on the surface of the inorganic fiber and are dispersed.
An inorganic fiber-bonded ceramic having a thick wall shape, wherein the thickness of the fiber in the laminating direction is more than 65 mm. (C) (i) an inorganic fiber comprising the following (a) and / or (b):
(A) an amorphous substance composed of Si, M, C and O (M represents Ti or Zr),
(B) (1) an aggregate of β-SiC, MC and C crystalline fine particles, and ( ₂ ) an amorphous substance of SiO ₂ and MO ₂ ,
(Ii) an inorganic material which fills the gaps between the inorganic fibers and comprises the following (c) and / or (d), and optionally (e) is dispersed:
(C) an amorphous material consisting of Si and O, optionally M;
(D) a crystalline substance comprising crystalline SiO ₂ and MO ₂ ,
(E) a crystalline fine particle inorganic material composed of MC having a particle size of 100 nm or less,
(Iii) a boundary layer of 1 to 100 nm in which crystalline particles composed of MC and having a particle diameter of 100 nm or less in some cases are formed on the surface of the inorganic fiber and are dispersed.
An inorganic fiber-bound ceramic composed of:
(D) An inorganic fiber comprising an inner surface layer and a surface layer, wherein the inner surface layer comprises:
(A) an amorphous substance composed of Si, M, C and O (M represents Ti or Zr);
(B) an aggregate of crystalline ultrafine particles of β-SiC, MC and C and an amorphous substance of SiO ₂ and MO ₂ , or (c) an amorphous substance of (a) and (b) Composed of an inorganic substance containing a mixture with an aggregate of the surface layer,
(D) an amorphous material comprising Si and O, optionally M;
(E) a crystalline substance composed of crystalline SiO ₂ and / or MO ₂ , or (f) an inorganic substance containing a mixture of the amorphous substance (d) and the crystalline substance (e). And the thickness T (unit μm) of the surface layer is T = aD (where a is a numerical value in the range of 0.023 to 0.053, and D is the diameter (unit μm) of the inorganic fiber. And a laminate of inorganic fibers that satisfies
The integrated preform formed of (C) and (D) was set in a carbon die and hot-pressed in an inert gas atmosphere at a temperature in the range of 1500 to 2000 ° C. and a pressure of 100 to 1000 kg / cm ^2. A method for producing a thick-walled inorganic fiber-bound ceramics, characterized by performing a treatment.

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