JP2012201566A - Inorganic fiber-bonded ceramic component and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic fiber-bonded ceramic component capable of including a complex form with high reliability and accuracy, and a method for producing the component which enables a complex form to be formed without defects such as cracks and chips inexpensively in a short period of time.SOLUTION: The method for producing the inorganic fiber-bonded ceramic component includes electric discharge machining of an inorganic fiber-bonded ceramic which comprises inorganic fibers comprising at least one of an amorphous substance containing Si, M, C and O, and an aggregate of crystalline fine particles containing β-SiC, MC and C and an amorphous substance containing SiOand MO; an inorganic substance comprising at least one of an amorphous substance containing Si and O, and a crystalline substance containing crystalline SiOand MO; and boundary layers composed mainly of C, and an inorganic fiber-bonded ceramic which comprises inorganic fibers composed mainly of a sintered structure of SiC and containing 0.01-1 mass% of O and specific metal atoms, and boundary layers composed mainly of C.

Description

  The present invention relates to a dense inorganic fiber-bonded ceramic component having high heat resistance and high fracture resistance and a method for producing the same, and in particular, it is exposed to a high temperature of 1200 ° C. or higher and is required to have high density and fracture resistance. Inorganic fiber-bonded ceramic parts applicable to precision parts having complicated shapes such as hollows, narrow holes, and curves, for example, combustor members for aerospace industry and gas turbine members for high-efficiency power generation, and manufacturing method thereof About.

  In general, dense heat-resistant ceramic materials have characteristics such as wear resistance and high fracture strength, and are attracting attention as machine structural materials, particularly high-temperature machine members. However, heat-resistant ceramic materials are harder and more brittle than metal materials, and as a method of processing into parts, machining by cutting is difficult, and grinding with diamond tools is often used. However, there are many problems that tool wear is severe, high-precision processing is not easy, and cost is high.

  For this reason, complex parts processing using an electric discharge machining method is performed for parts processing of conductive ceramics. This electric discharge machining method is a machining method for removing a part of the workpiece surface by arc discharge repeated between the electrode and the workpiece at a short cycle, and could not be machined mainly by conventional machining techniques. Applies to hard materials. In addition, since the electrode for electric discharge machining does not touch the workpiece, the machining load acting on the workpiece is very small, and it becomes possible to machine a fine shape that has been difficult to machine until now. However, ceramics that have undergone electric discharge machining are repeatedly melted and solidified, resulting in a heat-affected layer, residual thermal stress, and microcracking on the processed surface, resulting in reduced fracture resistance compared to that before electric discharge machining. Disadvantages are known. In Non-Patent Document 1, when silicon carbide ceramics are wire-discharge processed and the bending strength is compared, a 30-50% strength reduction is recognized compared to before wire-discharge machining. In heat-resistant structural materials, such a decrease in strength is an important drawback, which greatly hinders the selection of an electrical discharge machining method for ceramic parts.

  On the other hand, Patent Document 1 discloses an inorganic fiber-bonded ceramic having high surface accuracy and high fracture resistance. These have excellent mechanical properties even at a high temperature of 1300 ° C. or higher, and have a high density compared to ultrahigh temperature materials such as carbon fiber reinforced carbon matrix composites and ceramic fiber reinforced ceramic matrix composites. Excellent smoothness and superior characteristics such as non-instantaneous failure in fracture tests, non-linear behavior in stress-displacement curves, and high fracture resistance compared to general heat resistant ceramics represented by silicon carbide and silicon nitride. Have. Due to these features, application to high temperature members that require high dimensional accuracy is expected.

JP 2001-181046 A

Takemasa Kaneko et al., “Electrical Discharge Machining Characteristics of High-Strength Insulating Silicon Carbide Ceramics (2nd Report) Effect of Electrical Discharge Machining on Bending Strength Properties”, Proceedings of National Conference on Electrical Machining (2007), p. 325

  However, since the inorganic fiber-bonded ceramic described in Patent Document 1 is manufactured by processing high-temperature and high-pressure treatment of a woven fabric or a sheet-like laminate of inorganic fibers, the characteristics of the material in the fiber reinforcement direction and the fiber lamination direction Is characterized by having different properties. In particular, since the fracture strength in the fiber lamination direction is not sufficient compared to the fiber reinforcement direction, in order to process parts of this inorganic fiber-bonded ceramic into complex shapes such as hollow, thin-walled, thin holes, and curved shapes, A thorough understanding of various properties including anisotropy of mechanical properties and advanced machining techniques were necessary.

  Moreover, most of the machining to the part shape is a grinding method using a grindstone in which diamond abrasive grains are embedded, and the part is machined using a machine such as a surface grinder, a thin cutting machine, or a machining center. However, in the grinding method using the diamond grindstone, as described above, the grindstone to be used is expensive, the tool wear is severe, the machining of parts having a complicated shape is difficult, and the machining load is large, so the machining is in progress. There are problems such as parts being damaged. To grind precise inorganic fiber-bonded ceramic parts with complex shapes with high dimensional accuracy without damaging them, for example, in the production of thin-walled parts, the lamination of fiber materials constituting inorganic fiber-bonded ceramics It was important to suppress the occurrence of cracks in the direction, and it was essential to study grinding conditions that do not cause cracks in the stacking direction. For this reason, before manufacturing a regular part, pre-process a part with the same shape as or close to that of the regular part under various conditions, and select the optimal conditions that do not cause cracks in the stacking direction and do not require processing time. Was. This selection of conditions required costs and a period for preparing the preliminary material. In addition, since the selected condition is a condition that suppresses the processing load on the part, the processing time is longer than usual, which greatly affects the manufacturing cost. In addition, if it becomes possible to process a shape that cannot be manufactured by conventional machining, the application range of the inorganic fiber bonded ceramic parts will be greatly expanded.

  Accordingly, the present invention provides an inorganic fiber bonded ceramic component that can include complex shapes such as thin wall, hollow, narrow hole, and curve with high heat resistance, high fracture resistance, high reliability and accuracy, and low cost in a short period of time. In addition, an object of the present invention is to provide a method for producing the inorganic fiber-bonded ceramic part which is free from defects such as cracks and chips and can form a complicated shape.

  In order to achieve the above object, as a result of intensive studies, the present inventors have conducted electric discharge machining of inorganic fiber-bonded ceramics in which a boundary layer containing C as a main component is formed on the surface of inorganic fibers. It has been found that inorganic fiber-bonded ceramic parts can be manufactured that can include complex shapes such as thin walls, hollows, narrow holes, and curves with high heat resistance and high fracture resistance, high reliability and accuracy.

That is, the present invention
(A1) inorganic fibers comprising at least one of the following (a1) and (a2);
(A1) An amorphous material containing Si, M, C and O (M represents Ti or Zr; the same shall apply hereinafter),
(A2) an aggregate of crystalline fine particles containing β-SiC, MC and C and an amorphous material containing SiO ₂ and MO ₂ ;
(A2) an inorganic substance consisting of at least one of the following (a3) and (a4), which fills the gap between the inorganic fibers;
(A3) an amorphous material containing Si and O,
(A4) a crystalline material containing crystalline SiO ₂ and MO ₂ ;
(A3) A boundary layer of 1 to 100 nm mainly composed of C formed on the surface of the inorganic fiber;
An inorganic fiber-bonded ceramics A component, characterized by subjecting the inorganic fiber-bonded ceramics A to electrical discharge machining.

The present invention also provides:
(B1) An inorganic fiber mainly including a sintered structure of SiC, at least one metal selected from the group consisting of 0.01 to 1% by mass of O, and metal atoms of 2A group, 3A group, and 3B group Inorganic fibers containing atoms;
(B2) a 1 to 100 nm boundary layer mainly composed of C formed on the surface of the inorganic fiber;
An inorganic fiber-bonded ceramic B component produced by subjecting an inorganic fiber-bonded ceramic B to electric discharge machining.

  The present invention also relates to an inorganic fiber bonded ceramic part obtained by the above manufacturing method.

  As described above, according to the present invention, the cracks generated in the conventional machining method are produced by electric discharge machining of inorganic fiber-bonded ceramics in which a boundary layer mainly composed of C is formed on the surface of inorganic fibers. It is possible to manufacture inorganic fiber-bonded ceramic parts with complex shapes such as thin wall, hollow, narrow hole, and curved with high reliability and accuracy, and preventing conventional defects such as chipping and chipping. It is possible to provide a method for producing an inorganic fiber-bonded ceramic part, characterized by having a fracture strength of a material equivalent to the above method.

It is the cross-sectional structure | tissue photograph which image | photographed the cross section of the inorganic fiber coupling | bonding ceramics A which concern on Example 1 with the electron microscope. It is the cross-sectional structure | tissue photograph which image | photographed the cross section after the wire electrical discharge machining of the inorganic fiber coupling | bonding ceramics A and the inorganic fiber coupling | bonding ceramics B which concern on Example 1 and Example 2 with the optical microscope. It is the cross-sectional structure | tissue photograph which image | photographed the cross section of the inorganic fiber coupling | bonding ceramics B which concern on Example 2 with the electron microscope. It is a photograph of the corrugated plate-shaped component obtained by processing the inorganic fiber-bonded ceramic according to Example 2 by the wire electric discharge machining method.

  In the present invention, the inorganic fiber bonded ceramic component is not limited to a specific component, but is a product obtained by subjecting the inorganic fiber bonded ceramic to electric discharge machining to have a shape, and the application is not limited. . Hereinafter, the inorganic fiber-bonded ceramics A and B will be described.

[Inorganic fiber-bonded ceramics A]
First, the inorganic fiber bonded ceramics A used for the inorganic fiber bonded ceramics A part according to the present invention will be described. In the inorganic fiber-bonded ceramic A, (A1) (a1) the amorphous material constituting the inorganic fiber includes an amorphous material containing Si, M, C, and O, and substantially Si, M, C And an amorphous material composed of O and O. Hereinafter, M represents Ti or Zr.

In addition, (A1) an aggregate of the crystalline fine particles and the amorphous substance constituting the inorganic fiber includes (a2) crystalline fine particles containing β-SiC, MC and C, and non-containing materials containing SiO ₂ and MO _2. An aggregate with a crystalline substance is preferable.

  The (A1) inorganic fiber may be a mixture of these (a1) amorphous substance and (a2) an aggregate of crystalline fine particles and amorphous substance. (A1) The ratio of each element which comprises an inorganic fiber is Si: 30-60 mass%, M: 0.5-35 mass%, Preferably it is 1-10 mass%, C: 25-40 mass%, O: It is preferable that it is 0.01-30 mass%. (A1) The equivalent diameter of the inorganic fiber is generally 5 to 20 μm.

  In the inorganic fiber-bonded ceramics A, (A2) (a3) the amorphous material constituting the inorganic material includes an amorphous material containing Si and O, and an amorphous material substantially composed of Si and O Preferably, the amorphous material may contain M.

Further, (A2) the crystalline substance constituting the inorganic substance (a4) includes a crystalline substance containing SiO ₂ and MO _2, and is a crystalline substance substantially composed of crystalline SiO ₂ and MO _2. Preferably there is.

  Further, (A2) the inorganic substance preferably contains (a5) crystalline fine particles as a constituent element, and (A2) the crystalline fine particles constituting the inorganic substance (a5) have a particle diameter of 100 nm or less. In particular, crystalline fine particles consisting essentially of MC having a particle size of 100 nm or less are preferable.

  (A2) The ratio of each element which comprises an inorganic substance is Si: 20-65 mass%, M: 0.3-40 mass%, Preferably it is 1-15 mass%, C: 30-55 mass%, O: It is preferable that it is 0-5 mass%. The (A2) inorganic substance is present so as to fill the gaps between the (A1) inorganic fibers and acts to bind the inorganic fibers.

  In the inorganic fiber-bonded ceramics A, (A1) the boundary layer formed on the surface of the inorganic fiber (A3) is a boundary layer of 1 to 100 nm substantially comprising C as a main component. Crystalline fine particles made of MC having the following particle diameter may be dispersed. This boundary layer acts as a sliding layer when the inorganic fiber-bonded ceramic A is broken, and serves to prevent the crack from proceeding straight. In addition, it is a characteristic that a certain degree of electrical conductivity is required for a workpiece in electric discharge machining. Since this boundary layer mainly composed of C has conductivity, this inorganic fiber-bonded ceramic A is It has an important effect on electric discharge machining.

  Reflecting the structure shown above, this inorganic fiber-bonded ceramic A is excellent in fracture toughness and very dense. The strength at 1500 ° C. maintains extremely high mechanical properties of 80% or more of room temperature strength. ing.

[Method of manufacturing inorganic fiber-bonded ceramics A part]
Next, the manufacturing method of the inorganic fiber bonded ceramic A component according to the present invention will be described. In the method for producing an inorganic fiber-bonded ceramic A part according to the present invention, the raw material (A0) inorganic fiber is, for example, polydimethyl synthesized using dimethyldichlorosilane as a starting material and dechlorinated with metal sodium. Polycarbosilane synthesized by heat polycondensation of silane at 450 ° C. or higher is used as a precursor. This polycarbosilane is melt-spun, infusibilized at 100 to 200 ° C. in air, and subsequently fired at 1000 to 1300 ° C. in nitrogen, whereby (a01) amorphous containing Si, M, C and O An aggregate of a crystalline material, (a02) crystalline fine particles containing β-SiC, MC and C and an amorphous material containing SiO ₂ and MO ₂ , or (a03) an amorphous material of (a01) above (A0) inorganic fiber comprised with the inorganic substance containing a mixture with the aggregate | assembly of said (a02) can be obtained.

  Such (A0) inorganic fiber can be produced, for example, according to the method described in JP-A-62-289614, and a commercially available product such as Tyranno fiber (registered trademark: manufactured by Ube Industries, Ltd.) is used. You can also. The equivalent diameter of this (A0) inorganic fiber is generally 5 to 20 μm.

Next, (A0) the inorganic fiber is heated in an oxidizing atmosphere at a temperature of 500 to 1500 ° C., preferably 800 to 1200 ° C. Examples of the oxidizing atmosphere include air, pure oxygen, ozone, water vapor, and carbon dioxide gas. By the heating, (A0) the surface of the inorganic fiber is oxidized, (A0) (a04) an amorphous substance containing Si and O on the surface of the inorganic fiber, (a05) at least of crystalline SiO ₂ and MO ₂ (A02) an inorganic substance composed of a crystalline substance including one or (a06) an inorganic substance containing a mixture of the amorphous substance (a04) and the crystalline substance (a05). The The thickness of this (A02) inorganic substance is generally 10 to 600 nm.

By passing through the oxidation step, the (A0) inorganic fiber used as a raw material becomes an (A01) inorganic fiber in which the inner surface layer is composed of (A0) inorganic fiber and the surface layer is composed of (A02) inorganic substance. The obtained (A01) inorganic fiber has an inner layer (a01) amorphous material containing Si, M, C and O, (a02) crystalline fine particles containing β-SiC, MC and C, and SiO _2. And an amorphous material containing MO ₂ or (a03) an inorganic material containing a mixture of the amorphous material (a01) and the aggregate (a02). (A04) an amorphous material containing Si and O, (a05) a crystalline material containing at least one of crystalline SiO ₂ and MO ₂ , or (a06) the amorphous material of (a04) and the above ( (A01) is an inorganic fiber that is composed of an inorganic material containing a mixture of the crystalline material of a05) and the surface layer thickness T (unit: μm) satisfies the following formula (1). As the inner layer, for example, (a01) an amorphous substance substantially composed of Si, M, C and O, (a02) a substantially solid solution of β-SiC, MC, β-SiC and MC, MC _{1− An} amorphous substance of SiO ₂ and MO ₂ in which crystalline fine particles consisting of one or more of _x and C are dispersed, and (a03) these (a01) amorphous substances and (a02) crystalline fine particles are dispersed. It is possible to use at least one mixture of amorphous materials. The (a04) amorphous material of the surface layer may further contain M.

  The inner surface layer thus formed is made of (A0) inorganic fibers and the surface layer is made of (A02) inorganic substances. (A01) inorganic fibers form inorganic fiber-bonded ceramics. (A1) inorganic fibers and (A2) inorganic substances And the constituent elements (substances) and their proportions are the same.

  Next, a preform (I) is produced. First, the inner surface layer and the surface layer manufactured as described above are (A02) made of an inorganic substance. (A01) Woven inorganic fibers, sheets in which fibers are oriented in one direction, fiber bundles, or chopped shapes obtained by cutting continuous fibers The short fiber is cut into at least one shape, and the shapes are laminated to form the preform (I).

  Next, the preform (I) is sintered under pressure in an inert gas atmosphere to constitute the inorganic fiber-bonded ceramic A used in the present invention (A1) inorganic fibers, (A2) inorganic substances, and A (A3) boundary layer of 1 to 100 nm is formed. Examples of the inert gas include argon and nitrogen. The sintering temperature is a temperature in the range of 1400 to 2000 ° C, preferably 1500 to 1900 ° C. When the sintering temperature is lower than 1400 ° C., the bonding between the inorganic fibers is insufficient, and excellent mechanical properties cannot be expressed. On the other hand, if the sintering temperature exceeds 2000 ° C., the thermal decomposition reaction of the inorganic fibers proceeds and it becomes difficult to obtain a homogeneous inorganic fiber-bonded ceramic A.

  Examples of the pressure sintering method include a hot press method in which molding and sintering are performed simultaneously, and a hot isostatic pressing method (HIP method).

  When sintering is performed by a hot press method, a carbon sheet or boron nitride sprayed as a mold release agent is used for the mold made of carbon, and 20 to 60 MPa, preferably 30 to 20 in an inert gas atmosphere. The inorganic fiber-bonded ceramics A can be obtained by simultaneously heating the preformed body (I) at a pressure of 50 MPa and heating it.

  When sintering by the HIP method, the preform (I) is set in a glass or metal capsule, the inside of the capsule is vacuum-sealed, and 20 to 80 MPa in an inert gas atmosphere, preferably The inorganic fiber-bonded ceramics A can be obtained by simultaneously heating an encapsulated preform (I) at a pressure of 30 to 70 MPa while applying isotropic pressure. The glass capsule is not particularly limited, but fused quartz having excellent heat resistance is preferable. The metal capsule is a metal having a melting point of 1400 ° C. or higher, and a high melting point metal such as tantalum or niobium is preferable.

  Roughing for processing the inorganic fiber-bonded ceramics A obtained by the pressure sintering process from a raw material to a shape close to the final part shape is performed by a surface grinding machine, a thin cutting machine, or a machining center. Then, finish processing of complex shaped parts such as thin, hollow, fine holes, and curved parts of inorganic fiber-bonded ceramics A material or rough processed material that has been processed to a shape close to the shape of the final part by electrical discharge machining To do. Of course, the machining of the simple shape portion that does not require the electric discharge machining method may be performed by a conventional machining method. The electric discharge machining methods include sculpting electric discharge machining, wire electric discharge machining, and fine hole electric discharge machining, which are selected according to the part shape. By using this electric discharge machining method, it is possible to manufacture a precise inorganic fiber-bonded ceramic A part free from defects such as cracks and chips.

[Inorganic fiber-bonded ceramics B]
Next, the inorganic fiber bonded ceramic B used for the inorganic fiber bonded ceramic B component according to the present invention will be described. In the inorganic fiber-bonded ceramic B, (B1) inorganic fibers include inorganic fibers mainly composed of a sintered structure of SiC, and are substantially 0.01 to 1% by mass of O, 2A group, 3A group, and 3B. Preferably, it contains at least one metal atom selected from the group consisting of group metal atoms and is bonded to a structure very close to closest packing.

  The inorganic fiber having a sintered structure of SiC mainly has a polycrystalline sintered structure of β-SiC, and preferably contains β-SiC and C crystalline fine particles. In a region where β-SiC crystal particles containing C crystallites and / or a very small amount of O are sintered without intergranular second phase, a strong bond between SiC crystals is obtained. If the fracture occurs in the fiber, it proceeds in the SiC crystal grains in a region of at least 30% or more. In some cases, intergranular fracture regions and intergranular fracture regions between SiC crystals coexist.

  (B1) The inorganic fiber contains at least one metal atom selected from the group consisting of 2A group, 3A group, and 3B group metal elements. Among the metal elements of Group 2A, Group 3A and Group 3B, Be, Mg, Y, Ce, B, and Al are particularly preferable, and these are all known as SiC sintering aids, and are organic. There are chelates and alkoxide compounds that can react with Si-H bonds of silicon polymers. If the proportion of this metal is excessively small, sufficient crystallinity of the fiber material cannot be obtained, and if the proportion is excessively high, the grain boundary fracture increases and the mechanical properties are deteriorated. (B1) The ratio of the elements constituting the inorganic fiber is usually Si: 55 to 70% by mass, C: 30 to 45% by mass, O: 0.01 to 1% by mass, 2A group, 3A group, and 3B group. Metal element: 0.05 to 4.0 mass%, preferably 0.1 to 2.0 mass%.

  In the inorganic fiber-bonded ceramic B, (B1) the boundary layer formed on the surface of the inorganic fiber (B2) is preferably a boundary layer of 1 to 100 nm substantially containing C as a main component. This boundary layer acts as a sliding layer when the inorganic fiber-bonded ceramic is broken, and serves to prevent the crack from proceeding straight. In addition, it is a characteristic that a certain degree of electrical conductivity is required for the workpiece in electric discharge machining, but since the boundary layer mainly composed of C has conductivity, the inorganic fiber bonded ceramic B is discharged. It has an important effect on processing.

  Reflecting the structure shown above, this inorganic fiber-bonded ceramic B is excellent in fracture toughness and very dense, and maintains extremely high mechanical properties equivalent to room temperature strength even at 1600 ° C.

[Method for producing inorganic fiber-bonded ceramic B part]
Next, the manufacturing method of the inorganic fiber bonded ceramic B component according to the present invention will be described. In the method for producing an inorganic fiber-bonded ceramic B component according to the present invention, the inorganic fiber (B0) used as a raw material is polysilane having a molar ratio of carbon atoms to silicon atoms of 1.5 or more, or a heated reaction product thereof. First step of preparing a metal element-containing organosilicon polymer containing at least one metal element selected from the group consisting of 2A group, 3A group, and 3B group metal elements, melt spinning the metal element-containing organosilicon polymer The second step of obtaining a spun fiber, the third step of preparing the infusible fiber by heating the spun fiber at 50 to 170 ° C. in an oxygen-containing atmosphere, and the fourth step of mineralizing the infusible fiber in an inert gas Can be obtained by:
Each step will be described in detail.

First Step In the first step, a metal-containing organosilicon polymer that is a precursor polymer is prepared.
Polysilane is a linear or cyclic heavy compound obtained by dechlorinating one or more kinds of dichlorosilane using sodium, for example, according to the method described in “Chemistry of Organosilicon Compounds” Chemistry (1972). The number average molecular weight is usually 300 to 1,000. In the present invention, the polysilane can have a hydrogen atom, a lower alkyl group, a phenyl group or a silyl group as a silicon side chain. In any case, the ratio of carbon atoms to silicon atoms is 1.5 by mole. That is necessary. If this condition is not satisfied, all of the carbon in the fiber is desorbed as carbon dioxide in the temperature rising process until sintering, together with the oxygen introduced during infusibilization, and no boundary carbon layer between the fibers is formed. Therefore, it is not preferable.

  In the present invention, the polysilane includes an organosilicon polymer partially containing a carbosilane bond, in addition to the polysilane bond unit, obtained by heating the above-mentioned chain or cyclic polysilane. Such an organosilicon polymer can be prepared by a method known per se. Examples of the preparation method include a method in which a linear or cyclic polysilane is heated and reacted at a relatively high temperature of 400 to 700 ° C., a phenyl group-containing polyborosiloxane is added to the polysilane, and a relatively low temperature of 250 to 500 ° C. The method of heating reaction can be mentioned. The number average molecular weight of the organosilicon polymer thus obtained is usually 1000 to 5000.

  The phenyl group-containing polyborosiloxane can be prepared according to the method described in JP-A Nos. 53-42300 and 53-50299. For example, a phenyl group-containing polyborosiloxane can be prepared by a dehydrochlorination condensation reaction between boric acid and one or more types of diorganochlorosilane, and the number average molecular weight is usually 500 to 10,000. The addition amount of the phenyl group-containing polyborosiloxane is usually 15 parts by weight or less with respect to 100 parts by weight of the polysilane.

  By adding a predetermined amount of a compound containing a metal element of 2A group, 3A group and 3B group to polysilane and reacting in an inert gas at a temperature usually in the range of 250 to 350 ° C. for 1 to 10 hours A metal element-containing organosilicon polymer can be prepared. The above-mentioned metal element is used in such a ratio that the content ratio of the metal element in the inorganic fibers constituting the finally obtained inorganic fiber-bonded ceramic B (B1) is 0.05 to 4.0% by mass, and the specific ratio Can be appropriately determined by one skilled in the art according to the teachings of the present invention. The metal element-containing organosilicon polymer is a crosslinked polymer having a structure in which at least a part of silicon atoms of polysilane are bonded with or without metal atoms and oxygen atoms.

  As the compound containing a metal element of Group 2A, Group 3A, and Group 3B added in the first step, an alkoxide, acetylacetoxide compound, carbonyl compound, cyclopentadienyl compound, or the like of the metal element can be used. Examples include beryllium acetylacetonate, magnesium acetylacetonate, yttrium acetylacetonate, cerium acetylacetonate, butanoic acid borate, and aluminum acetylacetonate. These all react with the Si-H bond in the organosilicon polymer produced during the reaction with polysilane or its heated reaction product, and each metal element is bonded to Si directly or via other elements. It can be generated.

Second Step In the second step, a spun fiber of a metal element-containing organosilicon polymer is obtained. The metal element-containing organosilicon polymer as a precursor polymer can be spun by a method known per se such as melt spinning and dry spinning to obtain a spun fiber.

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 fiber so that the infusible fiber does not melt in the subsequent mineralization step and adjacent fibers do not fuse. It is to be. Examples of the gas constituting the oxygen-containing atmosphere include air, oxygen, and ozone. The infusibilization time depends on the infusibilization temperature, but is usually several minutes to 30 hours. It is desirable to control the oxygen content in the infusible fiber so as to be 8 to 16% by mass. 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 in the temperature rising process until the final sintering. To do. When the oxygen content is less than 8% by mass, excess carbon in the inorganic fiber remains more than necessary, and segregates around the SiC crystal in the temperature rising process and stabilizes, so that the β-SiC crystals are separated from each other. Sintering without intervening through the second phase of the interface is inhibited, and when the amount is more than 16% by mass, surplus carbon in the inorganic fiber is completely desorbed and a boundary carbon layer between the fibers is not generated. Both of these adversely affect the mechanical properties of the resulting material.

  The infusible fiber is preferably preheated in an inert atmosphere. Nitrogen, argon, etc. can be illustrated as gas which comprises inert atmosphere. The heating temperature is usually 150 to 800 ° C., and the heating time is several minutes to 20 hours. By preheating the infusible fiber in an inert atmosphere, while preventing oxygen uptake into the fiber, the cross-linking reaction of the polymer constituting the fiber is further advanced, and the infusible fiber from the precursor polymer is excellent. Thus, the strength can be further improved while maintaining the elongation, whereby the mineralization in the next step can be performed stably with good workability.

Fourth Step In the fourth step, the infusible fiber is mineralized by heat treatment at a temperature in the range of 1000 to 1700 ° C. in an inert gas atmosphere such as argon in a continuous or batch manner.

  Next, a preform (II) is prepared from the (B0) inorganic fiber obtained in the first to fourth steps. (B0) Inorganic fiber is cut into at least one shape of a woven fabric, a sheet in which the fibers are oriented in one direction, a fiber bundle, or a chopped short fiber obtained by cutting continuous fibers, and the shape is laminated to prepare Formed body (II) is formed.

  Next, the preform (II) is sintered under pressure in an inert gas atmosphere to constitute inorganic fiber-bonded ceramics B used in the present invention (B1) inorganic fibers, 1 to 100 nm (B2) A boundary layer is formed. Examples of the inert gas include argon and nitrogen. Sintering temperature is 1500-2200 degreeC, Preferably, it is the temperature of the range of 1700-2000 degreeC.

  Examples of the pressure sintering method include a hot press method in which molding and sintering are performed simultaneously, and a hot isostatic pressing method (HIP method).

  When sintering is performed by a hot press method, a carbon sheet or boron nitride sprayed as a release agent is used as a mold made of carbon, and 20 to 70 MPa in an inert gas atmosphere, preferably 30 to 30 MPa. The preform (II) is simultaneously heated while being pressurized at a pressure of 60 MPa, whereby the inorganic fiber-bonded ceramic B can be obtained.

  When sintering by the HIP method, the preform (II) is set in a glass or metal capsule, the inside of the capsule is vacuum-sealed, and 20 to 100 MPa in an inert gas atmosphere, preferably Inorganic fiber-bonded ceramics B can be obtained by simultaneously heating an encapsulated preform (II) at a pressure of 30 to 80 MPa while applying isotropic pressure. The glass capsule is not particularly limited, but fused quartz having excellent heat resistance is preferable. The metal capsule is a metal having a melting point of 1400 ° C. or higher, and a high melting point metal such as tantalum or niobium is preferable.

  Roughing for processing the inorganic fiber-bonded ceramic B obtained by the pressure sintering process from a raw material to a shape close to the final part shape is performed by a surface grinding machine, a thin cutting machine, or a machining center. Then, finish processing of complex shaped parts such as thin, hollow, fine holes, and curved parts of inorganic fiber-bonded ceramic B materials or rough processed materials that have been processed to a shape close to the shape of the final part using the electrical discharge machining method To do. Of course, the machining of the simple shape portion that does not require the electric discharge machining method may be performed by a conventional machining method. The electric discharge machining methods include sculpting electric discharge machining, wire electric discharge machining, and fine hole electric discharge machining, which are selected according to the part shape. By using this electric discharge machining method, it is possible to manufacture a precise inorganic fiber-bonded ceramic B component free from defects such as cracks and chips.

  The inorganic fiber bonded ceramic parts of the present invention include complex shapes such as thin walls, hollows, narrow holes, and curvatures that are obtained as described above, have high heat resistance, high fracture resistance, and high reliability and accuracy. Ceramic parts.

Examples are given below to explain the present invention in more detail. The mechanical properties according to the examples were measured as follows.
[Evaluation of mechanical properties]
Using a Tensilon universal testing machine (Orientec: RTC-1310A), the distance between the upper and lower fulcrums was 10 mm and 30 mm, respectively, and the 4-point bending strength was determined. The shape of the bending test piece was 4 mm in width, 3 mm in thickness, and 40 mm in length. The moving speed of the cross head in the bending test was 0.5 mm / min.

Example 1
A Tyranno fiber (registered trademark: manufactured by Ube Industries, Ltd.) having a fiber diameter of 10 μm was heat-treated in air at 1000 ° C. for 15 hours to produce inorganic fibers composed of a surface layer and an inner surface layer. A uniform surface layer having an average of about 300 nm corresponding to a = 0.030 in the above formula (1) was formed on the fiber surface. Next, this inorganic fiber insulator woven fabric sheet is prepared, cut into 90 mm × 90 mm, 150 sheets are laminated, set in a carbon die, and hot press molded at a temperature of 1800 ° C. and a pressure of 40 MPa in an argon atmosphere. As a result, an inorganic fiber-bonded ceramic A was obtained. When the cross section of the obtained inorganic fiber-bonded ceramics A was observed with an electron microscope, it was very dense with no voids or interlayer cracks, and a boundary layer composed mainly of C was uniformly formed on the fiber surface. FIG. 1 shows a cross-sectional structure photograph obtained by photographing a cross section of the inorganic fiber-bonded ceramic A according to Example 1 with an electron microscope.

  When the room temperature strength of a bending test piece taken from this inorganic fiber-bonded ceramics A material by a grinding method using a thin cutting machine and a surface grinding machine was measured, the average was 260 MPa, and the bending strength at 1400 ° C. was further measured. However, the average was 245 MPa, which was almost equivalent to the room temperature strength.

  Next, in order to investigate the effect of wire electric discharge machining on the strength of inorganic fiber-bonded ceramics A, bending is performed from the inorganic fiber-bonded ceramics A after hot pressing using a wire electric discharge machine (DWC90SZ manufactured by Mitsubishi Electric Corporation). Test specimens were collected. Wire electric discharge machining was performed using a brass wire having a diameter of 0.2 mm as the wire electrode wire, a machining feed rate of 0.5 mm / min, and an average machining voltage of 64V. The cross section of the inorganic fiber-bonded ceramic A after wire electric discharge machining was observed with an optical microscope to examine the presence or absence of interlayer cracks, but no cracks were confirmed. In FIG. 2, the cross-sectional structure | tissue photograph which image | photographed the cross section after the wire electric discharge machining of the inorganic fiber bond ceramics A which concern on Example 1 with the engineering microscope is shown. Moreover, when the 4-point bending strength at room temperature of the bending test piece collected by wire electric discharge machining was measured, the average strength was 255 MPa, which is equivalent to the material strength of the inorganic fiber bonded ceramic A collected by the grinding method. It was confirmed that there was no change in strength due to wire electric discharge machining.

(Example 2)
First, 1 L of dimethyldichlorosilane was dropped while heating and refluxing anhydrous xylene containing 400 g of sodium under a nitrogen gas stream, followed by heating and refluxing for 10 hours to generate 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 in n-butyl ether at 100 to 120 ° C. in a nitrogen gas atmosphere, and the resulting white resinous material is further heat-treated at 400 ° C. in vacuum for 1 hour. As a result, 530 g of a phenyl group-containing polyborosiloxane was obtained. 4 parts of this phenyl group-containing polyborosiloxane was added to 100 parts of the polydimethylsilane obtained above and subjected to thermal condensation at 350 ° C. for 5 hours in a nitrogen gas atmosphere to obtain a high molecular weight organosilicon polymer. Polyaluminocarbosilane was synthesized by adding 7 parts of aluminum-tri- (sec-butoxide) to a xylene solution in which 100 parts of this organosilicon polymer was dissolved, and causing a crosslinking reaction at 310 ° C. in a nitrogen gas stream. 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. This infusible fiber was continuously fired at 1500 ° C. in nitrogen to synthesize a silicon carbide-based continuous inorganic fiber. Next, this inorganic fiber insulator woven fabric sheet is prepared, cut into 90 mm × 90 mm, 150 sheets are laminated, set in a carbon die, and hot press molded at a temperature of 1900 ° C. and a pressure of 50 MPa in an argon atmosphere. As a result, an inorganic fiber-bonded ceramic B was obtained. When the cross section of the obtained inorganic fiber-bonded ceramic B material was observed with an electron microscope, the fiber was deformed to a shape close to a hexagonal column with a close-packed structure, and there was no void or interlayer crack and it was very dense. Moreover, the boundary layer which has C as a main component was producing | generating uniformly on the fiber surface. In FIG. 3, the structure | tissue photograph which image | photographed the cross section of the inorganic coupling | bonding ceramics B which concern on Example 2 with the electron microscope is shown.

  When the room temperature strength of a bending test piece taken from this inorganic fiber-bonded ceramic B material by a grinding method using a thin cutting machine and a surface grinding machine was measured, the average was 300 MPa, and the bending strength at 1500 ° C. was further measured. However, the average was 290 MPa, which was almost the same as the room temperature strength.

  Next, in order to investigate the influence of wire electric discharge machining on the strength of inorganic fiber-bonded ceramic B, bending is performed from the inorganic fiber-bonded ceramic B after hot pressing using a wire electric discharge machine (DWC90SZ, manufactured by Mitsubishi Electric Corporation). Test specimens were collected. As the wire electrode wire, a brass wire having a diameter of 0.2 mm was used, and wire electric discharge machining was performed at a machining feed rate of 2.0 mm / min and an average machining voltage of 55V. The surface of the inorganic fiber-bonded ceramic B after wire electric discharge machining was observed with an optical microscope to examine the presence or absence of interlayer cracks, but no cracks were confirmed. In FIG. 2, the cross-sectional structure | tissue photograph which image | photographed the cross section after the wire electric discharge machining of the inorganic fiber joint ceramic B which concerns on Example 2 with an engineering microscope is shown. Moreover, when the 4-point bending strength at room temperature of the bending specimen obtained by wire electric discharge machining was measured, the average strength was 295 MPa, which is equivalent to the material strength of the inorganic fiber-bonded ceramic B collected by the grinding method. It was confirmed that there was no change in strength due to wire electric discharge machining.

(Example 3)
From the inorganic fiber-bonded ceramic A material and the inorganic fiber-bonded ceramic B material obtained in Example 1 and Example 2, rough cutting was performed to a width of 13 mm, a height of 13 mm, and a length of 25 mm using a thin cutting machine and a surface grinder. After that, corrugated plate-shaped parts having a width of 0.4 mm and a height of 13 mm having thin portions and curved portions were collected by wire electric discharge machining. In FIG. 4, the photograph of the corrugated plate-shaped component which processed the inorganic fiber joint ceramic B which concerns on Example 2 by the wire electric discharge machining method is shown. The same applies to parts obtained by processing the inorganic fiber-bonded ceramics A according to Example 1 by the electric discharge machining method, and the photos are omitted. Such thin-walled and curved parts are very difficult because conventional machining methods have a large load during machining, and there is a high possibility that defects such as cracks and chips will occur in the parts, but electrical discharge machining is used. It was confirmed that it is possible to manufacture inorganic fiber bonded ceramic parts with high reliability and accuracy.

(Comparative Example 1)
From the inorganic fiber-bonded ceramic A material and the inorganic fiber-bonded ceramic B material obtained in Example 1 and Example 2, using the grinding method using a diamond grindstone, the same corrugated component collection as in Example 3 was obtained. However, due to the load during grinding, the inorganic fiber-bonded ceramic A material and B material were damaged in the interlayer direction.

  The present invention is a dense, heat-resistant and high fracture resistance inorganic fiber-bonded ceramic that has low cost in a short period of time and is free from defects such as cracks and chips, and has the same fracture strength as that of conventional machining methods. The present invention relates to a method for manufacturing an inorganic fiber-bonded ceramic part, characterized by performing electrical discharge machining into a complicated shape such as thin, hollow, thin hole, and curved with high reliability and accuracy.

  The inorganic fiber-bonded ceramic component according to the present invention has a complicated shape such as a thin wall, a hollow, a fine hole, and a curve, which are particularly exposed to a high temperature of 1200 ° C. or more and require high density and fracture resistance. The present invention can be applied to precision parts such as a combustor member for the aerospace industry and a gas turbine member for high-efficiency power generation.

DESCRIPTION OF SYMBOLS 1 Inorganic fiber which comprises inorganic fiber bond ceramics A 2 Inorganic substance which comprises inorganic fiber bond ceramics A 3 Fiber boundary layer which comprises inorganic fiber bond ceramics A and B 4 Inorganic fiber which comprises inorganic fiber bond ceramics B

Claims (6)

(A1) inorganic fibers comprising at least one of the following (a1) and (a2);
(A1) An amorphous material containing Si, M, C and O (M represents Ti or Zr; the same shall apply hereinafter),
(A2) an aggregate of crystalline fine particles containing β-SiC, MC and C and an amorphous material containing SiO ₂ and MO ₂ ;
(A2) an inorganic substance consisting of at least one of the following (a3) and (a4), which fills the gap between the inorganic fibers;
(A3) an amorphous material containing Si and O,
(A4) a crystalline material containing crystalline SiO ₂ and MO ₂ ;
(A3) A boundary layer of 1 to 100 nm mainly composed of C formed on the surface of the inorganic fiber;
A method for producing an inorganic fiber-bonded ceramic component, comprising subjecting an inorganic fiber-bonded ceramic material to electrical discharge machining.   The method for producing an inorganic fiber-bonded ceramic component according to claim 1, wherein (a3) is an amorphous substance further containing M.   The method for producing an inorganic fiber-bonded ceramic part according to claim 1 or 2, wherein (A2) further includes (a5) crystalline fine particles containing MC having a particle size of 100 nm or less.   The method for producing an inorganic fiber-bonded ceramic part according to any one of claims 1 to 3, wherein (A3) further includes crystalline fine particles containing MC having a particle diameter of 100 nm or less. (B1) An inorganic fiber mainly composed of a sintered structure of SiC, and at least one metal selected from the group consisting of 0.01 to 1% by mass of O and metal atoms of 2A group, 3A group, and 3B group Inorganic fibers containing atoms;
(B2) a 1 to 100 nm boundary layer mainly composed of C formed on the surface of the inorganic fiber;
A method for producing an inorganic fiber-bonded ceramic component, comprising subjecting an inorganic fiber-bonded ceramic material to electrical discharge machining. An inorganic fiber bonded ceramic part obtained by the manufacturing method according to claim 1.