JP5668575B2 - Inorganic fiber for fiber bundle, inorganic fiber bundle for composite material composed of inorganic fiber for fiber bundle, and ceramic matrix composite material reinforced with fiber bundle - Google Patents

Description

  The present invention relates to an inorganic fiber for a fiber bundle, an inorganic fiber bundle for a composite material composed of the inorganic fiber for the fiber bundle, and a ceramic matrix composite material reinforced with the fiber bundle.

  Ceramic matrix composites reinforced with inorganic fibers are being developed as next-generation heat-resistant materials because of their excellent heat resistance not found in metals and damage tolerance not found in conventional single-phase ceramics. In ceramic-based composite materials, the bond at the interface between the reinforcing fiber and the matrix is controlled, and cracks are deflected at the interface when the material breaks, and the breakage progresses while the fiber pulls out. It is a feature. In particular, a ceramic matrix composite material reinforced with silicon carbide fibers using non-oxide silicon carbide or silicon nitride as a matrix has attracted particular attention. Expected uses of these ceramic matrix composite materials include the gas turbine field and the like, and durability under a high temperature and oxidizing atmosphere is required.

  As a method for producing a ceramic matrix composite material, a preform is produced by molding a woven fabric of inorganic fibers as a reinforcing material into a desired shape. Next, after the sizing agent used to converge the fiber bundle is decomposed and removed in an inert atmosphere such as argon or nitrogen at a high temperature of 600 ° C. or higher, an interface layer for controlling the interface with the matrix is controlled. It is formed on the fiber surface by chemical vapor deposition (CVD method, CVI method). As the interface layer, carbon or boron nitride is mainly selected. Next, the matrix is similarly subjected to chemical vapor deposition, or a method of impregnating an inorganic or organic polymer melt or solution as a matrix raw material, followed by firing, and repeating this step if necessary. There is a method of forming a ceramic matrix composite material by (impregnation / firing method).

  In this manufacturing process, when each fiber in the fiber bundle comes into contact, a uniform interface layer is not formed at the contact point, and there is a problem that adversely affects the characteristics of the composite material. For example, in Non-Patent Document 1, in a ceramic matrix composite material of a silicon carbide matrix reinforced with silicon carbide fibers, an interface layer of boron nitride is not uniformly formed at the contact point of the fibers in the fiber bundle. It is shown that when the fiber is subjected to stress in a high temperature / oxidizing atmosphere, the fiber contact point is preferentially oxidized to form an oxide glass layer. It has been pointed out that fibers are firmly bonded by this glass layer, causing stress concentration, causing brittle fracture, and the expected durability cannot be obtained. Therefore, it is said that it is important for ensuring the durability of the ceramic matrix composite material that the fibers in the fiber bundle are separated so that the interface layer can be uniformly formed on the fiber surface. In order to solve such a problem, it has been proposed to attach short fibers, powder, or whiskers of a heat-resistant substance to the fiber surface (Patent Documents 1 and 2, Non-Patent Document 2).

JP-A-63-59473 JP-A-62-299568

J. et al. Am. Ceram. Soc. , 83 [6] 1441-49 (2000) Mater. Trans. 44 [6] 1172-80 (2003)

  However, by attaching these heat-resistant substances to the fiber surface, it is possible to avoid contact between the fibers in the fiber bundle, but the heat-resistant substances are also decomposed in the sizing agent removal process, interface layer formation process and matrix formation process. Does not remain in the composite material. In particular, in the interface layer forming step, where the heat-resistant substance adheres to the fiber surface, the interface layer is not formed on the fiber surface, and fiber pull-out is suppressed at the time of destruction. Does not show energy. Furthermore, the heat-resistant substance has a high hardness like inorganic fibers, and also has an irregular shape and an edge shape, so in the process of adhering to the fiber surface or the process of weaving the fibers into a fabric, etc. Due to the friction, the heat-resistant substance damages the fiber and the fiber strength is lowered. Therefore, there is a problem that the strength of the obtained composite material is also lowered.

  In view of such problems of the prior art, the present invention provides a ceramic-based composite material exhibiting sufficient strength and fracture energy, and excellent durability when subjected to stress in a high temperature / oxidizing atmosphere. Suppressing the decrease in fiber strength due to fiber damage during production of inorganic fiber bundles for materials, and avoiding contact between fibers in fiber bundles during production of composite materials, and interfacing with the matrix on the entire fiber surface An object of the present invention is to provide an inorganic fiber for a fiber bundle capable of forming a layer, an inorganic fiber bundle for a composite material composed of the inorganic fiber for the fiber bundle, and a ceramic matrix composite material reinforced with the fiber bundle.

  As a result of intensive studies on the inorganic fiber bundles for composite materials satisfying such conditions, the present inventors meandered in the longitudinal direction, had a specific meandering pitch and meandering width, and the fiber diameter changed in the longitudinal direction. The present inventors have found that the object of the present invention can be achieved by forming a fiber bundle composed of inorganic fibers having a difference between a specific maximum diameter and a minimum diameter.

  That is, the present invention relates to an inorganic fiber for a fiber bundle constituting an inorganic fiber bundle for a composite material, meandering in the longitudinal direction, a meandering pitch of 3 to 40 mm, a meandering width of 0.1 to 5 mm, and a diameter of The present invention relates to an inorganic fiber for fiber bundles, characterized in that the difference between the maximum diameter and the minimum diameter is 2 to 6 μm and the change pitch is 10 to 200 mm.

  In the present invention, the elemental composition is Si: 45-60 mass%, Ti or Zr: 0.2-5 mass%, C: 20-45 mass%, O: 0.1-20.0 mass%. It is related with the said inorganic fiber for fiber bundles characterized by including.

Further, the present invention has a density of 2.7 g / cm ³ or more, a tensile strength of 2 GPa or more, and an elastic modulus of 250 GPa or more, Si: 50 to 70% by mass, C: 28 to 45% by mass, Al: 0.00. The present invention relates to the inorganic fiber for fiber bundles, characterized in that it is a crystalline silicon carbide fiber comprising 06 to 3.8% by mass and B: 0.06 to 0.5% by mass and having a sintered structure of SiC.

  Moreover, this invention relates to the inorganic fiber bundle for composite materials comprised from the said inorganic fiber for fiber bundles.

  The present invention also relates to a ceramic matrix composite material characterized in that the inorganic fiber bundle for composite material is a reinforcing fiber and ceramic is a matrix.

  In addition, the present invention relates to the ceramic matrix composite material, wherein the inorganic fiber bundle for composite material is a two-dimensional or three-dimensional fabric, a unidirectional sheet-like material, or a laminate thereof.

  The inorganic fiber bundle for composite materials composed of inorganic fibers for fiber bundles according to the present invention avoids contact between fibers without damaging the fibers in the inorganic fiber bundle, and an interfacial layer on the entire surface of each fiber By using the inorganic fiber bundle for composite materials according to the present invention, a ceramic matrix composite material exhibiting sufficient strength and fracture energy and excellent durability when subjected to stress in a high temperature / oxidizing atmosphere. Can be obtained.

It is an optical microscope photograph which shows the meander pitch and meander width of the inorganic fiber for fiber bundles which concerns on this invention. It is an example of the measurement result of the change of the diameter of a fiber longitudinal direction. (A) Example 1, (b) Comparative example 1, (c) Example 2, (d) Comparative example 2, (e) Example 3, (f) Optical microscope of the cross section of each fiber bundle of Comparative example 3 It is a photograph.

  The inorganic fiber for a fiber bundle according to the present invention is preferably a silicon carbide fiber in view of heat resistance and oxidation resistance. The inorganic fiber for a fiber bundle according to the present invention meanders in the longitudinal direction, the meandering pitch is 3 to 40 mm, preferably 5 to 15 mm, and the meandering width is 0.1 to 5 mm, preferably 0.2 to 2 mm. And the difference between the maximum diameter and the minimum diameter is 2 to 6 μm, more preferably 3 to 5 μm, and the pitch of the change is 10 to 200 mm, more preferably, When the fiber bundle is configured by setting the fiber bundle to 30 to 150 mm, a space is formed between the fibers in the fiber bundle due to a change in the fiber diameter, and contact between the fibers in the fiber bundle can be substantially avoided. An interface layer with the matrix can be formed on the entire surface. When the meandering pitch is less than 3 mm, the deviation of orientation due to meandering of each fiber increases with respect to the orientation direction of the fiber bundle in the composite material, and the fiber strength does not act effectively, thereby reducing the mechanical properties of the composite material. It is not preferable. When the meandering pitch is larger than 40 mm, the space due to meandering becomes insufficient, and contact between fibers in the fiber bundle increases, which is not preferable. If the meandering width is less than 0.1 mm, the space due to meandering becomes insufficient, and the contact between the fibers in the fiber bundle increases, which is not preferable. When the meandering width is larger than 5 mm, the deviation of orientation due to meandering of each fiber increases with respect to the orientation direction of the fiber bundle in the composite material, the fiber strength does not act effectively, and the mechanical properties of the composite material are deteriorated. Therefore, it is not preferable. If the difference between the maximum diameter and the minimum diameter is less than 2 μm, the space due to the change in the fiber diameter becomes insufficient, and contact between the fibers in the fiber bundle increases, which is not preferable. In addition, since the fiber strength depends on the minimum diameter part, if the difference between the maximum diameter and the minimum diameter is larger than 6 μm, the minimum diameter part becomes small and breaks at a low load, thus lowering the mechanical properties of the composite material. It is not preferable. The average diameter of the silicon carbide fiber is preferably 11 to 20 μm, more preferably 13 to 17 μm. When it becomes thinner than 11 μm, the change in the longitudinal direction of the diameter with respect to the fiber diameter becomes too large, and the fiber strength is lowered. When it is larger than 20 μm, the flexibility of the fiber is impaired, and processing such as weaving of the fiber bundle becomes difficult.

  Here, in the inorganic fiber for a fiber bundle according to the present invention, the meandering in the longitudinal direction means a state in which the fibers extend while meandering, and the meandering pitch is adjacent to each other among peaks and troughs repeated in the extending direction. The meandering width is the distance between the peaks of a mountain and a valley or the peak of a valley and a valley. This is the distance in the vertical direction (width direction). As shown in FIG. 1, this meandering pitch is obtained by continuously photographing a single fiber in the longitudinal direction with an optical microscope, and measuring the distance in the extension direction between an arbitrary peak and the apex of an adjacent valley from the optical microscope photograph. It can be determined by measuring and doubling the 10 average values. Similarly, the meandering width can be obtained from an average value of 10 measured distances in the width direction between an arbitrary peak and the apex of the adjacent valley from an optical microscope.

  Here, in the inorganic fiber for a fiber bundle according to the present invention, the difference between the maximum diameter and the minimum diameter was obtained by photographing five fibers having a length of 300 mm with an optical microscope at intervals of 10 mm in the longitudinal direction. The fiber diameter is measured, the difference between the maximum value and the minimum value of each fiber is obtained, and the average value can be obtained. The change pitch is obtained from the average value of the distances between the portions where the fiber diameter at the measurement location is larger than the fiber diameters on both sides for each fiber.

  The inorganic fiber for a fiber bundle according to the present invention has an element composition of Si: 45-60 mass%, Ti or Zr: 0.2-5 mass%, C: 20-45 mass%, O: 0.1-20. It is preferable to contain 0.0 mass%. Examples of such silicon carbide fibers include ZMI fiber and LoxM fiber (registered trademark) manufactured by Ube Industries, Ltd. By adding Ti or Zr, the heat resistance is improved, and in particular by adding Zr, the oxidation resistance and alkalinity can also be improved. By using the inorganic fiber bundle for composite material composed of the inorganic fiber for fiber bundle as a reinforcing fiber, a ceramic matrix composite material having excellent characteristics can be obtained.

The inorganic fiber for a fiber bundle according to the present invention has a density of 2.7 g / cm ³ or more, a tensile strength of 2 GPa or more, and an elastic modulus of 250 GPa or more, Si: 50 to 70% by mass, C: 28 to 45. % By mass, Al: 0.06 to 3.8% by mass, preferably 0.13 to 1.25% by mass, and B: 0.06 to 0.5% by mass, preferably 0.06 to 0.19% by mass It is preferable that it is a crystalline silicon carbide fiber containing a sintered structure of SiC. As such crystalline silicon carbide fiber, there is SA fiber (registered trademark) manufactured by Ube Industries, Ltd. When the proportion of aluminum is excessively small, the alkali resistance of the crystalline silicon carbide fiber is lowered, and when the proportion is excessively high, mechanical properties at high temperatures are lowered. If the proportion of boron is too small, it will not be a sufficiently sintered crystalline fiber, and the density of the fiber will decrease, conversely, if the proportion is too high, the alkali resistance of the fiber will decrease. become. Crystalline silicon carbide fibers exhibiting excellent alkali resistance due to excellent heat resistance and high strength and elastic modulus obtained by making them crystalline, and excellent presence of aluminum are obtained, and are composed of inorganic fibers for this fiber bundle. By using the inorganic fiber bundle for composite materials as reinforcing fibers, a ceramic-based composite material having excellent characteristics can be obtained.

  The method for producing an inorganic fiber for a fiber bundle according to the present invention includes a spinning step of spinning an organosilicon polymer, and an infusibilization step of insolubilizing the obtained spun fiber by heat treatment in an oxidizing atmosphere or electron beam irradiation. And a firing step of firing the obtained infusible fiber in an inert atmosphere or a reducing atmosphere.

The spinning process first comprises a carbosilane (—Si—CH ₂ —) bond unit and a polysilane (—Si—Si—) bond unit, and a hydrogen atom, lower alkyl group, aryl group, phenyl group on the side chain of silicon. And an organosilicon polymer having a group selected from the group consisting of silyl groups, and heating a compound selected from the group consisting of an alkoxide of Ti or Zr, an acetylacetoxy compound, a carbonyl compound, a cyclopentadienyl compound, and an amine compound A Ti or Zr-containing organosilicon polymer is prepared by reaction. Next, this Ti or Zr-containing organosilicon polymer is melt-spun. The spinning speed is preferably 100 to 300 m / min. More preferably, for the gear pump that supplies the polymer to the spinning nozzle, a pump with a large pulsation of protrusion is selected, and the amount of polymer supplied to the spinning nozzle is varied by periodically changing the rotation speed. In the process, the fiber diameter can be changed in the longitudinal direction. If it is faster than 300 m / min, the tension applied to the fiber during spinning becomes high and the change in diameter becomes small, which is not preferable. If it is slower than 100 m / min, the change in diameter becomes large and the productivity is also lowered, which is not preferable.

  The infusibilization step is performed, for example, by infusibilizing the obtained spun fiber. For infusibility, a method known per se can be adopted, the infusibility temperature in an oxidizing atmosphere is 50 to 300 ° C., and the electron beam irradiation is 2 to 4 MV at an acceleration voltage of 2 to 15 KGy / sec. dose, 10-20 MGydose.

  The firing step is performed on the obtained infusible fiber in an inert atmosphere, preferably in the range of 1100 to 1600 ° C. without applying tension to the fiber. Thereby, the fibers can be meandered in the longitudinal direction. In order not to apply tension to the fiber, in the process in which the infusibilized fiber is mineralized during firing, the fiber shrinks in the radial direction and the longitudinal direction of the fiber in order to reduce the weight. It is to be. Thereby, a fiber can meander in a longitudinal direction in the process in which an infusible fiber mineralizes. In this firing process, the change in the longitudinal direction of the diameter introduced in the spinning step described above changes in a similar shape, so it can be almost maintained, and the meandering pitch, meandering width, and maximum diameter can be maintained. And a fiber bundle inorganic fiber having a minimum diameter difference and a changing pitch.

  As a method of carrying out without applying tension to the fiber at the time of firing, spinning is carried out by a cans method, a predetermined length (usually 500 to 1000 m) is spun into a circular shape with a diameter of 20 to 50 cm on a tray, and this is oxidized. Infusibilization is performed by heat treatment in a neutral atmosphere or electron beam irradiation. Next, this is achieved by firing in an inert atmosphere using a batch-type firing furnace or a pusher-type firing furnace capable of continuously firing a plurality of trays on which infusibilized fibers are set.

  Alternatively, the spinning is continuously wound around a drum, and then a predetermined length (usually 500 to 1000 m) is suspended in a circular shape having a diameter of 20 to 50 cm on a tray and then infusibilized. Alternatively, after infusibilization, a predetermined length (usually 500 to 1000 m) is suspended in a circular shape having a diameter of 20 to 50 cm on the tray. After that, similarly to the above, it may be fired in an inert atmosphere using a batch-type firing furnace or a pusher-type firing furnace capable of continuously firing a plurality of trays in which infusible fibers are set. Good.

  The inorganic fiber for a fiber bundle according to the present invention can be practically used as an inorganic fiber bundle for a composite material after being fired in an inert atmosphere and wound around a bobbin. At this time, in order to improve the handleability of the fiber bundle, it is preferable to immerse in water, an organic solvent or a mixture of both in which a resinous sizing agent is dissolved and wind it while drying.

  As the resinous sizing agent, all known resins can be used. Specific examples thereof include poval resin, polyethylene oxide, epoxy resin, modified epoxy resin, polyester resin, polyimide resin, phenol resin, polyurethane resin. , Polyamide resin, polycarbonate resin, silicon resin, phenoxy resin, polyphenylene sulfide, fluorine resin, hydrocarbon resin, halogen-containing resin, acrylic acid resin, and ABS resin. In particular, poval resin and polyethylene oxide are used for commercially available inorganic fibers, and are particularly preferable. Although there is no restriction | limiting in particular as an adhesion amount, 0.01-10 mass% with respect to inorganic fiber, Especially 0.1-5 mass% is preferable. If it is less than 0.01% by mass, the fiber bundle does not converge, and if it exceeds 10% by mass, the degree of convergence does not change and the sizing agent is used wastefully.

  When the inorganic fiber for a fiber bundle according to the present invention is a crystalline silicon carbide fiber having a sintered structure of SiC, the inorganic fiber for a fiber bundle has 0.05 to 3% by mass of Al and 0% of B. 0.05 to 0.4% by mass, and 1 to 2% by mass of surplus carbon, and an amorphous silicon carbide fiber having a difference between the maximum diameter and the minimum diameter and a pitch of change is 1600 to 2100 ° C. It can be obtained by baking and crystallizing without applying tension in a temperature and in an inert atmosphere within the range. In order not to apply tension to the fiber, the process of crystallizing amorphous silicon carbide fiber during heating causes weight loss and shrinkage in the radial and longitudinal directions of the fiber, accompanied by volume shrinkage. It is to avoid restraint. Thereby, the crystalline silicon carbide fiber having the meandering pitch, the meandering width, and the difference between the maximum diameter and the minimum diameter and the change pitch can be provided. The amorphous silicon carbide fiber preferably contains 8 to 16% by mass of oxygen. When heating the amorphous silicon carbide fiber, this oxygen desorbs the above-mentioned excess carbon as CO gas, and brings the ratio of Si and C close to the stoichiometric ratio of SiC, so that the crystalline silicon carbide fiber Can be obtained.

  This amorphous silicon carbide fiber can be prepared, for example, by the following method. First, for example, according to the method described in “Chemistry of Organosilicon Compounds” Chemistry Dojin (1972), one or more dichlorosilanes are dechlorinated with sodium to prepare a linear or cyclic polysilane. The number average molecular weight of polysilane is usually 300-1000. In this specification, the polysilane is obtained by heating the chain or cyclic polysilane to a temperature in the range of 400 to 700 ° C., or adding a phenyl group-containing polyborosiloxane to the chain or cyclic polysilane. Also included is a polysilane partially having a carbosilane bond obtained by heating to a temperature in the range of 250 to 500 ° C. The polysilane can have a hydrogen atom, a lower alkyl group, an aryl group, a phenyl group or a silyl group as a side chain of silicon.

  Next, a predetermined amount of aluminum alkoxide, acetylacetoxide compound, carbonyl compound, or cyclopentadienyl compound is added to polysilane, and 1 to 10 at a temperature usually in the range of 250 to 350 ° C. in an inert gas. By reacting for a time, an aluminum-containing organosilicon polymer that is a raw material for spinning is prepared. The amount of the aluminum compound used is usually 0.14 to 0.86 mmol per 1 g of polysilane.

  A spun fiber is prepared by melt spinning an aluminum-containing organosilicon polymer. The spinning speed is preferably 100 to 300 m / min. More preferably, for the gear pump that supplies the polymer to the spinning nozzle, a pump with a large pulsation of protrusion is selected, and the amount of polymer supplied to the spinning nozzle is varied by periodically changing the rotation speed. In the process, the fiber diameter can be changed in the longitudinal direction. If it is faster than 300 m / min, the tension applied to the fiber during spinning becomes high and the change in diameter becomes small, which is not preferable. If it is slower than 100 m / min, the change in diameter becomes large and the productivity is also lowered, which is not preferable. Next, the spinning fiber is infusibilized in an oxidizing atmosphere to prepare an infusible fiber, and then fired in an inert gas such as nitrogen or argon at a temperature in the range of 1100 to 1600 ° C. A crystalline silicon carbide based fiber is prepared. In the longitudinal direction of the diameter, which is accompanied by weight reduction and volume reduction during the main firing and the subsequent firing in an inert atmosphere at a temperature in the range of 1600 to 2100 ° C., which was introduced in the spinning process. Since the change changes in a similar manner, it can be almost maintained.

  The ceramic matrix composite material according to the present invention is characterized in that the inorganic fiber bundle for composite material obtained as described above is used as a reinforcing fiber and ceramic is used as a matrix. There is no restriction | limiting in particular in the form of this inorganic fiber bundle for composite materials, Two-dimensional or three-dimensional textiles, such as a plain weave and a satin weave, a one-way sheet-like thing, or those laminated bodies may be sufficient. Although there is no special restriction | limiting about the volume ratio of the inorganic fiber in a composite material, 10 to 50% is common.

  The composite method is not particularly limited, but after coating a preform woven with inorganic fibers with boron nitride or carbon as an interface layer, a ceramic precursor polymer such as polycarbosilane, polymetallocarbohydrate, etc. A polymer impregnation / firing method in which silane, polysilazane, etc. are dissolved in a solvent such as xylene, impregnated and dried, and then heated and fired to form a composite, impregnated with a slurry of matrix raw material powder, and hot press etc. Pressure-sintering method, sol-gel method using matrix element alkoxide as raw material, chemical vapor deposition method that forms matrix by reaction of reaction gas at high temperature, and impregnation with molten metal at high temperature to make ceramic by reaction A reaction sintering method can be used. There is also a method in which a part of the matrix is formed by chemical vapor deposition and then the remaining space is densified by reaction sintering or polymer impregnation / firing.

  The ceramic matrix of the present invention includes crystalline or amorphous oxide ceramics, crystalline or amorphous non-oxide ceramics, glass, crystallized glass, a mixture thereof, and those obtained by dispersing these ceramic particles. preferable.

  Specific examples of oxide ceramics include aluminum, magnesium, silicon, yttrium, indium, uranium, calcium, scandium, tantalum, niobium, neodymium, lanthanum, ruthenium, rhodium, beryllium, titanium, tin, strontium, barium, zinc, zirconium. And oxides of elements such as iron and complex oxides of these metals.

Specific examples of non-oxide ceramics include carbides, nitrides and borides. Specific examples of the carbide include carbides of elements such as silicon, titanium, zirconium, aluminum, uranium, tungsten, tantalum, hafnium, boron, iron, and manganese, and composite carbides of these elements. Examples of this composite carbide include inorganic substances obtained by heating and baking polytitanocarbosilane or polyzirconocarbosilane. Specific examples of nitrides include nitrides of elements such as silicon, boron, aluminum, magnesium, and molybdenum, composite oxides of these elements, and sialon. Specific examples of borides include borides of elements such as titanium, yttrium, and lanthanum, and platinum boride lanthanoids such as CeCoB ₂ , CeCo ₄ B ₄ , and ErRh ₄ B ₄ .

Specific examples of the glass include amorphous glass such as silicate glass, phosphate glass, and borate glass. Specific examples of the crystallized glass include LiO ₂ —Al ₂ O ₃ —MgO—SiO ₂ glass and LiO ₂ —Al ₂ O ₃ —MgO—SiO ₂ —Nb ₂ O ₅ whose main crystal phase is β-spudene. system glass, the main crystal phase _MgO-Al 2 O 3 -SiO ₂ based glass is cordierite, the main crystal phase is barium male solid light _BaO-MgO-Al 2 O 3 -SiO ₂ based glass, the main crystalline phase Examples thereof include BaO—Al ₂ O ₃ —SiO ₂ based glass that is mullite or hexacelsian, and CaO—Al ₂ O ₃ —SiO ₂ based glass whose main crystal phase is anorthite. The crystal phase of these crystallized glasses may contain cristobalite. Examples of the ceramic in the present invention include solid solutions of the above-mentioned various ceramics.

  As a specific example of the particle dispersion strengthened ceramics, the ceramic matrix is selected from silicon nitride, silicon carbide, zirconium oxide, magnesium oxide, potassium titanate, magnesium borate, zinc oxide, titanium boride and mullite. Examples include inorganic particles of spherical particles, polyhedral particles, plate-like particles, rod-like particles, and ceramics in which 0.1 to 60% by volume of whiskers are uniformly dispersed. The particle size of spherical particles and polyhedral particles is 0.1 μm to 1 mm, and the aspect ratio of plate-like particles, rod-like particles and whiskers is generally 1.5 to 1000.

  Next, examples are given to describe the present invention more specifically, but the present invention is not limited to the following examples.

Example 1
0.5 parts by mass of polyborodiphenylsiloxane was added to 100 parts by mass of polydimethylsilane, and this mixture was heated and reacted at 380 ° C. for 10 hours in a nitrogen atmosphere to synthesize about 70 parts by mass of polycarbosilane having a weight average molecular weight of 1000. . 5 parts by mass of zirconium acetylacetonate was added to this polycarbosilane, and the mixture was reacted by heating at 300 ° C. for 3 hours in a nitrogen atmosphere to obtain polyzirconocarbosilane. The polyzirconocarbosilane was squeezed at a speed of 200 m / min with a multi-hole nozzle of 400 at about 250 ° C. while periodically rotating the gear pump for supplying the polymer between 20-22 rpm. According to the method, 1000 m was melt-spun into a circular shape having a diameter of about 40 cm on a carbon tray. Next, infusibilization was performed by heat treatment in air at 180 ° C. for 5 hours. Then, it set in the state put on the tray in the batch-type baking furnace, and baked at 1450 degreeC in nitrogen for 1 hour. Then, it is immersed in an aqueous solution containing 1% by mass of polyethylene oxide, wound on a bobbin while drying at 200 ° C., meandered in the longitudinal direction, and used for a composite material composed of inorganic fibers for fiber bundles whose diameter has changed in the longitudinal direction. An inorganic fiber bundle was produced.

  The obtained inorganic fiber bundle for composite material has a silicon carbide-based chemical composition having a mass ratio of Si: 55.5%, O: 9.8%, C: 34.1%, Zr: 0.6%. It was a fiber (average diameter: 16.5 μm, 400 fibers / fiber bundle, sizing agent: polyethylene oxide). Table 1 shows the measurement results of the meandering pitch and meandering width, the maximum and minimum diameters, the difference between them, and the pitch of the change obtained by the method described above. FIG. 2 shows an example in which the diameter of a fiber having a length of 300 mm is measured at intervals of 10 mm, and the change in the diameter in the longitudinal direction of the fiber is measured.

  Moreover, the cross section in the inorganic fiber bundle for composite materials obtained in this way was observed with an optical microscope. The micrograph is shown in FIG. Further, the tensile strength of the obtained fiber bundle was measured by the JIS R7601 resin impregnated strand method, and the results are shown in Table 1.

Comparative Example 1
In Example 1, melt spinning was performed while continuously winding on a drum at a rotation speed of a gear pump for supplying a polymer of 20 rpm, a spinning speed of 400 m / min. Next, infusibilization was performed by heat treatment in air at 180 ° C. for 5 hours. Then, while continuously firing at 1450 ° C. in a nitrogen atmosphere at a tension of 200 g, it is immersed in an aqueous solution added with 1% by mass of polyethylene oxide and wound at 200 ° C. and wound on a bobbin to form an inorganic fiber bundle for composite materials. Produced.

  The obtained inorganic fiber bundle for composite material has a silicon carbide-based chemical composition having a mass ratio of Si: 55.5%, O: 9.8%, C: 34.1%, Zr: 0.6%. It was a fiber (average diameter: 14 μm, 400 fibers / fiber bundle, sizing agent: polyethylene oxide). Table 1 shows the measurement results of the meandering pitch and meandering width, the maximum diameter and the minimum diameter, the difference between them, and the pitch of the change measured by the same method as in Example 1.

  Moreover, the cross section in the inorganic fiber bundle for composite materials obtained in this way was observed with an optical microscope. The micrograph is shown in FIG. Further, the tensile strength of the obtained fiber bundle was measured by the JIS R7601 resin impregnated strand method, and the results are shown in Table 1.

Example 2
0.5 parts by mass of polyborodiphenylsiloxane was added to 100 parts by mass of polydimethylsilane, and this mixture was heated and reacted at 380 ° C. for 10 hours in a nitrogen atmosphere to synthesize about 70 parts by mass of polycarbosilane having a weight average molecular weight of 1000. . 10 parts by mass of tetrabutyl titanate was added to this polycarbosilane, and the mixture was reacted by heating at 300 ° C. for 3 hours in a nitrogen atmosphere to obtain polytitanocarbosilane. The polytitanocarbosilane was drummed at a speed of 250 m / min with 400 multi-hole nozzles at about 270 ° C. while periodically rotating the speed of the gear pump for supplying the polymer between 20-22 rpm. The melt spinning was carried out while continuously winding. Thereafter, the spun fiber wound around the drum was suspended in a circular shape having a diameter of about 30 cm on a carbon tray by 700 m. Next, infusibilization was performed by heat treatment in air at 180 ° C. for 5 hours. Thereafter, 10 sets of these were produced and fired at 1350 ° C. in nitrogen at a feed rate of 1 m / hour using a pusher-type firing furnace. Then, it is immersed in an aqueous solution containing 1% by mass of polyethylene oxide, wound on a bobbin while drying at 200 ° C., meandered in the longitudinal direction, and used for a composite material composed of inorganic fibers for fiber bundles whose diameter has changed in the longitudinal direction. An inorganic fiber bundle was produced.

  The obtained inorganic fiber bundle for composite materials has a silicon carbide-based chemical composition with a mass ratio of Si: 54.4%, O: 10.2%, C: 33.9%, Ti: 1.5%. It was a fiber (average diameter: 16 μm, 400 fibers / fiber bundle, sizing agent: polyethylene oxide). Table 1 shows the measurement results of the meandering pitch and meandering width, the maximum and minimum diameters, the difference between them, and the change pitch.

  Moreover, the cross section in the inorganic fiber bundle for composite materials obtained in this way was observed with an optical microscope. The photomicrograph is shown in FIG. Further, the tensile strength of the obtained fiber bundle was measured by the JIS R7601 resin impregnated strand method, and the results are shown in Table 1.

Comparative Example 2
In Example 2, melt spinning was performed while continuously winding on a drum at a rotation speed of a gear pump for supplying a polymer of 20 rpm, a spinning speed of 450 m / min. Next, infusibilization was performed by heat treatment in air at 180 ° C. for 5 hours. Then, while continuously firing at 1350 ° C. under a nitrogen atmosphere at 1350 ° C., it is immersed in an aqueous solution added with 1% by mass of polyethylene oxide and wound at 200 ° C. and wound on a bobbin to form an inorganic fiber bundle for composite materials. Produced.

  The obtained inorganic fiber bundle for composite materials has a silicon carbide-based chemical composition with a mass ratio of Si: 54.4%, O: 10.2%, C: 33.9%, Ti: 1.5%. It was a fiber (average diameter: 14.2 μm, 400 fibers / fiber bundle, sizing agent: polyethylene oxide). Table 1 shows the measurement results of the meander pitch and meander width, the maximum diameter, the minimum diameter, the difference between them, and the change pitch.

  Moreover, the cross section in the inorganic fiber bundle for composite materials obtained in this way was observed with an optical microscope. The micrograph is shown in FIG. Further, the tensile strength of the obtained fiber bundle was measured by the JIS R7601 resin impregnated strand method, and the results are shown in Table 1.

Example 3
0.5 parts by mass of polyborodiphenylsiloxane was added to 100 parts by mass of polydimethylsilane, and this mixture was heated and reacted at 380 ° C. for 10 hours in a nitrogen atmosphere to synthesize about 70 parts by mass of polycarbosilane having a weight average molecular weight of 1000. . 4 parts by mass of aluminum trisecondary butoxide was added to this polycarbosilane, and the mixture was reacted by heating at 300 ° C. for 3 hours in a nitrogen atmosphere to obtain polyaluminocarbosilane. This polyaluminocarbosilane is applied to the drum at a speed of 150 m / min while the number of rotations of the gear pump supplying the polymer is periodically increased or decreased between 20-22 rpm at about 250 ° C. by 400 multi-hole nozzles. Melt spinning was performed while continuously winding. Next, infusibilization was performed by heat treatment in air at 180 ° C. for 5 hours. Thereafter, continuous firing was performed at 1400 ° C. in a nitrogen atmosphere, and the product was immersed in an aqueous solution added with 1% by mass of polyethylene oxide and wound on a bobbin while being dried at 200 ° C. As a result, an amorphous silicon carbide fiber containing 1.0% by mass of Al, 0.2% by mass of B, and 1.5% by mass of surplus carbon was obtained. Next, 1000 m was dropped in a circular shape having a diameter of about 30 cm on a carbon tray, set in a batch-type firing furnace, placed on the tray, and heat-treated at 1800 ° C. in argon for 1 hour for crystallization. Then, it was immersed in an aqueous solution added with 1% by mass of polyethylene oxide and wound on a bobbin while being dried at 200 ° C., to prepare an inorganic fiber bundle for composite materials composed of inorganic fibers for fiber bundles having a diameter changed in the longitudinal direction. .

  The obtained inorganic fiber bundle for composite materials has a chemical composition of mass ratio of Si: 67.8%, C: 31%, O: 0.3%, Al: 0.84%, B: 0.06. % (Atomic ratio Si: C: O: Al = 1: 1.07: 0.008: 0.013) crystalline silicon carbide fiber (average diameter: 15 μm, 400 pieces / fiber bundle, sizing agent: polyethylene oxide) Met. Table 1 shows the measurement results of the meander pitch and meander width, the maximum diameter, the minimum diameter, the difference between them, and the change pitch.

  Moreover, the cross section in the inorganic fiber bundle for composite materials obtained in this way was observed with an optical microscope. The micrograph is shown in FIG. Further, the tensile strength of the obtained fiber bundle was measured by the JIS R7601 resin impregnated strand method, and the results are shown in Table 1.

Comparative Example 3
In Example 3, the rotation speed of the gear pump for supplying the polymer was kept constant at 20 rpm, and the spinning speed was 500 m / min. Subsequently, similarly, infusibilization and continuous firing were performed, and the obtained amorphous silicon carbide containing 1.0% by mass of Al, 0.2% by mass of B, and 1.5% by mass of excess carbon. The fiber is crystallized under continuous heating at 1800 ° C. under a tension of 100 g, immersed in an aqueous solution to which 1% by mass of polyethylene oxide has been added, wound on a bobbin while being dried at 200 ° C., and a composite material An inorganic fiber bundle was prepared.

  The obtained inorganic fiber bundle for composite materials has a chemical composition of mass ratio of Si: 67.8%, C: 31%, O: 0.3%, Al: 0.84%, B: 0.06. % (Atomic ratio Si: C: O: Al = 1: 1.07: 0.008: 0.013) crystalline silicon carbide fiber (average diameter: 12.5 μm, 400 fibers / fiber bundle, sizing agent: polyethylene Oxide). Table 1 shows the measurement results of the meander pitch and meander width, the maximum diameter, the minimum diameter, the difference between them, and the change pitch.

  The cross section in the inorganic fiber bundle for composite materials thus obtained was observed with an optical microscope. The micrograph is shown in FIG. Further, the tensile strength of the obtained fiber bundle was measured by the JIS R7601 resin impregnated strand method, and the results are shown in Table 1.

  The results obtained in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 will be described below. From FIG. 3, Examples 1, 2, and 3 have a fiber bundle that is wider than Comparative Examples 1, 2, and 3, respectively, and in the longitudinal direction, the meandering pitch and meandering width of the present invention are imparted to the fiber diameter. In the longitudinal direction, the effect of imparting the difference between the maximum diameter and the minimum diameter of the present invention is recognized. On the other hand, it can be seen from Comparative Examples 1, 2, and 3 that even if meandering in the longitudinal direction and changing the diameter in the longitudinal direction, the fiber bundle hardly spreads and is not effective outside the scope of the present invention. Thus, in the present invention, it can be seen that the fiber spacing in the fiber bundle can be increased widely and appropriately while maintaining the fiber strength.

Example 4
The inorganic fiber bundle for composite material of Example 1 was woven into a three-dimensional fabric (fiber ratio is X: Y: Z = 1: 1: 0.2). Subsequently, the sizing agent was decomposed and removed at 1000 ° C. in argon, and then an interface layer of boron nitride and a matrix of silicon carbide were formed by chemical vapor deposition to produce a ceramic matrix composite material. The interface layer had a thickness of about 0.5 μm at 1000 ° C. under reduced pressure using boron trichloride and ammonia as source gases and argon as a carrier gas. The matrix was densified at 1000 ° C. under reduced pressure using methyltrichlorosilane as a source gas and helium as a carrier gas. The porosity after forming the matrix was about 10%, and the fiber deposition rate was 40%.

  A part of the three-dimensional woven fabric before complexing was loosened, a fiber bundle was extracted, and the tensile strength was measured by the JIS R7601 resin-impregnated strand method. Moreover, the tensile test piece was processed from the produced ceramic matrix composite material, and the tensile strength and breaking strain at room temperature were measured. In addition, durability was evaluated by measuring the time to break by applying 60% of the tensile strength at room temperature at 1000 ° C. in the atmosphere. Table 2 shows the tensile strength of the fiber extracted from the three-dimensional fabric, the tensile strength and breaking strain at room temperature of the ceramic matrix composite material, and 60% of the tensile strength at room temperature. Time to break at 1000 ° C. is shown.

Example 5
A ceramic matrix composite material was produced in the same manner as in Example 4 using the inorganic fiber bundle for composite material of Example 2.

  Table 2 shows the tensile strength of the fiber extracted from the three-dimensional fabric, the tensile strength and breaking strain at room temperature of the ceramic matrix composite material, and 60% of the tensile strength at room temperature. Time to break at 1000 ° C. is shown.

Example 6
A ceramic matrix composite material was produced in the same manner as in Example 4 using the inorganic fiber bundle for composite material of Example 3.

  Table 2 shows the tensile strength of the fiber extracted from the three-dimensional fabric, the tensile strength and breaking strain at room temperature of the ceramic matrix composite material, and 60% of the tensile strength at room temperature. Time to break at 1000 ° C. is shown.

Comparative Example 4
Using the inorganic fiber bundle for composite material of Comparative Example 1, a ceramic matrix composite material was produced and evaluated in the same manner as in Example 4. Table 2 shows the tensile strength of the fiber extracted from the three-dimensional fabric, the tensile strength and breaking strain at room temperature of the ceramic matrix composite material, and 60% of the tensile strength at room temperature. Time to break at 1000 ° C. is shown.

Comparative Example 5
Using the inorganic fiber bundle for composite material of Comparative Example 2, a ceramic matrix composite material was prepared and evaluated in the same manner as in Example 5. Table 2 shows the tensile strength of the fiber extracted from the three-dimensional fabric, the tensile strength and breaking strain at room temperature of the ceramic matrix composite material, and 60% of the tensile strength at room temperature. Time to break at 1000 ° C. is shown.

Comparative Example 6
Using the inorganic fiber bundle for composite material of Comparative Example 3, a ceramic matrix composite material was produced and evaluated in the same manner as in Example 6. Table 2 shows the tensile strength of the fiber extracted from the three-dimensional fabric, the tensile strength and breaking strain at room temperature of the ceramic matrix composite material, and 60% of the tensile strength at room temperature. Time to break at 1000 ° C. is shown.

  The results obtained in Examples 4, 5, and 6 and Comparative Examples 4, 5, and 6 will be described below. There is no decrease in the tensile strength of the fibers. From this, it can be seen that the tensile strength of the fiber does not decrease even when a complicated weaving such as a three-dimensional fabric is performed by meandering in the longitudinal direction and changing the diameter in the longitudinal direction.

  As for the tensile strength and breaking strain at room temperature of the ceramic matrix composite material, the ceramic matrix composite materials of Examples 4, 5, and 6 have values higher than those of Comparative Examples 4, 5, and 6 in both tensile strength and fracture strain. Show. From the fracture surface observation, in Examples 4 and 6, it was confirmed that there was no contact between the fibers in the fiber bundle, and that the interface layer of boron nitride was uniformly formed on the surface of each fiber, and the pullout of the fibers was also remarkable. Observed, it was confirmed that the interface layer functions effectively. This is considered to be the reason why high strength and fracture strain were obtained. In Example 5, since the spread of the fiber bundle of Example 2 is smaller than the spread of the fiber bundle of Examples 1 and 3, compared with Examples 4 and 6, fibers in a part of the fiber bundle Contact was observed. At these contact points, the boron nitride interface layer is not formed, and the fiber pull-out is reduced, which is considered to be the reason for the slightly lower value.

  In Comparative Examples 4, 5, and 6, most of the fibers in the fiber bundle were in contact with each other from the observation of the fracture surface, and no interface layer was formed at the contact location. Moreover, there was little pull-out of the fiber, and the fiber breakage occurred from the contact point between the fibers, and it was confirmed that the contact point was the cause of stress concentration. Thus, although the fiber strength does not decrease until it is processed into a three-dimensional fabric, the stress concentration due to the contact point between the fibers and the non-uniform interface layer are considered to be causes of low strength and breaking strain.

  With respect to the time to break at 1000 ° C. in the atmosphere with a stress of 60% of the tensile strength at room temperature of the ceramic matrix composite material, the ceramic matrix composite materials of Examples 4, 5, and 6 Although it is a slightly low value at 5, the fracture times longer than those of Comparative Examples 4, 5, and 6 are shown. In the fracture surface observations of Examples 4 and 6, fiber pullout was less than that of the fracture surface after the tensile test at room temperature, but was observed remarkably, and the glass layer formation due to oxidation of the fiber and interface layer was slight. It was. In Example 5, as compared with Examples 4 and 6, a slightly larger amount of the glass layer was observed due to the contact between the fibers, which is considered to be the cause of the slightly lower value. The breaking time is the longest in Example 6 and the shortest in Example 5. This is because it depends on the heat resistance of the fiber itself, the heat resistance of the fiber of Example 3 is the best, and the heat resistance of the fiber of Example 2 is the poorest.

  In the fracture surface observation of Comparative Examples 4, 5, and 6, most of the fibers in the fiber bundle were in contact with each other, and a glass layer was remarkably observed in the vicinity of the contact point. The formation of a large amount of these preferential glass layers is considered to cause the fibers to be strongly bonded to each other, causing stress concentration, causing brittle fracture, and shortening the fracture time. The breaking time is the longest in Comparative Example 6 and the shortest in Comparative Example 5 among the Comparative Examples. This is because, as described above, it depends on the heat resistance of the fiber itself, the heat resistance of the fiber of Comparative Example 3 is the best, and the heat resistance of the fiber of Comparative Example 2 is the poorest. .

  INDUSTRIAL APPLICABILITY The present invention can be used for producing inorganic fiber bundles for reinforcing fibers of ceramic matrix composite materials and ceramic matrix composite materials reinforced with these fibers.

Claims (6)

  In the inorganic fiber for a fiber bundle constituting the inorganic fiber bundle for a composite material, meandering in the longitudinal direction, the meandering pitch is 3 to 40 mm, the meandering width is 0.1 to 5 mm, and the diameter is changed in the longitudinal direction. An inorganic fiber for a fiber bundle, wherein the difference between the maximum diameter and the minimum diameter is 2 to 6 μm, and the change pitch is 10 to 200 mm.   Elemental composition contains Si: 45-60 mass%, Ti or Zr: 0.2-5 mass%, C: 20-45 mass%, O: 0.1-20.0 mass% The inorganic fiber for fiber bundles according to claim 1. The density is 2.7 g / cm ³ or more, the tensile strength is 2 GPa or more, the elastic modulus is 250 GPa or more, Si: 50 to 70 mass%, C: 28 to 45 mass%, Al: 0.06 to 3.8 mass % And B: 0.06 to 0.5 mass%, and is a crystalline silicon carbide fiber having a sintered structure of SiC.   The inorganic fiber bundle for composite materials comprised from the inorganic fiber for fiber bundles as described in any one of Claims 1-3.   A ceramic matrix composite material comprising the inorganic fiber bundle for composite materials according to claim 4 as a reinforcing fiber and ceramics as a matrix.   6. The ceramic matrix composite material according to claim 5, wherein the inorganic fiber bundle for the composite material is a two-dimensional or three-dimensional fabric, a unidirectional sheet, or a laminate thereof.

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