JP2017119589A - Ceramic composite material and method for producing ceramic composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic composite material of a structure in which the degradation of fibers themselves can be inhibited, and a method for producing a ceramic composite material.SOLUTION: A ceramic composite material 10 production method has an aggregate forming step for gathering SiC fibers 1 containing oxygen to form an aggregate 9, a CVD step P2 for putting the aggregate 9 into a CVD furnace and forming a ceramic coating 2 containing carbon on the surfaces of SiC fibers, and a silicon impregnation step P3 for impregnating the aggregate 9 with silicon.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a ceramic composite material and a method for producing a ceramic composite material.

  Ceramic composite materials such as SiC / SiC composite materials have high heat resistance and oxidation resistance, and are high-strength materials, and therefore are expected to be used in various fields such as high-temperature furnace members and semiconductor manufacturing equipment.

  Patent Document 1 describes an invention in which a fiber reinforced ceramic matrix composite (CMC) is immersed in molten silicon. This invention is a technique for preventing the preform from eroding while the preform is in contact with the molten silicon. Specifically, (a) a step of immersing the preform in a molten silicon bath, (b) a step of leaving the preform in the bath for a predetermined time, and (c) a step of drawing the preform out of the bath And (d) a step of cooling the preform. According to this method, it is described that this dipping process significantly reduces the time required to infiltrate the CMC preform, thus reducing the likelihood that molten silicon will erode the preform. .

JP 2006-206431 A

  The invention described above significantly reduces the time required to infiltrate the preform because the immersion time of the preform in the silicon bath is reduced, so that molten silicon will erode the preform. Although the potential can be reduced, preform erosion is occurring. For this reason, the deterioration of the fibers constituting the preform is not eliminated. For this reason, the fiber erosion cannot be essentially suppressed.

  In view of the above problems, an object of the present invention is to provide a ceramic composite material having a structure in which deterioration of the fiber itself can be suppressed and a method for manufacturing the ceramic composite material.

  The manufacturing method of the ceramic composite material of the present invention is as follows.

  (1) Aggregate forming step for collecting SiC fibers containing oxygen to form an aggregate; CVD step for forming the ceramic coating containing carbon on the surface of the SiC fibers by placing the aggregate in a CVD furnace; And a silicon impregnation step of impregnating the aggregate with silicon.

In the method for producing a ceramic composite material of the present invention, SiC fibers are aggregated to form an aggregate, and then put into a CVD furnace, a ceramic coating is formed on the surface of the SiC fibers, and silicon silicon is impregnated in a silicon impregnation step. Turn into. Further, a ceramic film containing carbon is formed on the SiC fiber by a CVD method. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon at a high temperature during production and use, it decomposes into SiO, dissipates as a gas, and causes deterioration of the SiC fiber. In the ceramic composite of the present invention, since a ceramic film containing high-purity carbon is formed by the CVD method, direct contact between metal silicon and SiO ₂ can be prevented, and deterioration of the SiC fiber itself is prevented. can do.

  Furthermore, it is preferable that the manufacturing method of the ceramic composite material of this invention is the following aspects.

  (2) The ceramic coating is composed of a pyrolytic carbon coating covering the SiC fiber and a SiC coating covering the outside of the pyrolytic carbon coating.

  Since the SiC film formed by the CVD method can use a high-purity source gas such as a mixed gas of silane and hydrocarbon or an organic silane gas, it has a high purity and does not contain oxygen. For this reason, SiO gas is not generated even if it contacts with metallic silicon. Further, since the pyrolytic carbon coating is formed between the SiC coating and the SiC fiber, the SiC fiber and the SiC coating are not integrated, and the reinforcing action of the SiC fiber can be maintained.

  (3) The method for producing the ceramic composite material includes a carbon precursor impregnation step of impregnating the aggregate with a carbon precursor between the CVD step and the silicon impregnation step, and heat treating the aggregate. And a heat treatment step of carbonizing the carbon precursor into a carbon matrix.

  In the method for producing a ceramic composite material of the present invention, oxygen-containing SiC fibers are aggregated to form an aggregate, and then put into a CVD furnace to form a ceramic coating on the surface of the SiC fiber, and then a carbon precursor is formed on the aggregate. The body is impregnated and heat treated to form a carbon matrix. Silicon expands by nearly 10% as it solidifies. For this reason, it is easy to generate a strong tension on the SiC fiber by volume expansion. By forming a carbon matrix inside the aggregate, the amount of silicon impregnated can be reduced, volume expansion due to solidification can be suppressed, tension applied to SiC fibers can be reduced, and the strength of the ceramic composite can be increased. it can.

  (4) The method for manufacturing the ceramic composite further includes a firing step of firing the aggregate and reacting the carbon matrix with the silicon to form SiC after the silicon impregnation step.

  Since the silicon silicon and the carbon matrix are reacted to form SiC by firing, the heat-resistant temperature is increased, and a ceramic composite material that can be stably used can be formed with less thermal deformation.

  (5) In the firing step, the processing temperature is 1410 to 1600 ° C.

  If the treatment temperature in the firing step is 1600 ° C. or lower, the deterioration of the SiC fiber can be suppressed, and if the treatment temperature in the firing step is 1410 ° C. or higher, the carbon matrix and the metal silicon are sufficiently reacted. I can.

  (6) The carbon precursor is at least one carbon precursor selected from a dispersion of pitch, copna resin, phenol resin, and carbon powder.

  The carbon precursor only needs to be carbonized by heat treatment. For example, in addition to organic substances such as pitch, copna resin, and phenol resin, a dispersion of carbon powder made of a solvent and carbon powder may be used. The organic matter is decomposed and carbonized by heat treatment, and in the dispersion of carbon powder, the solvent is volatilized by heat treatment and the carbon powder remains. In either case, since a part of the carbon precursor is removed, pores are formed, and silicon can be taken into the pores in the silicon impregnation step. When organic substances are used, the carbon matrices are integrated with each other, whereas when carbon powder is used, the carbon powder exists as discrete particles that are not bonded to each other. In this case, the separated particles can be fixed by the metallic silicon impregnated in the subsequent silicon impregnation step.

  Further, an organic substance such as pitch, copna resin, phenol resin, and carbon powder may be used at the same time. When the carbon powder and the organic substance are used at the same time, the yield of carbonization is high, and the amount of remaining metal silicon can be reduced.

  Any carbon powder may be used. For example, carbon cracks, coke powder, amorphous coke powder, graphite powder and the like can be used. The 50% volume cumulative diameter of the carbon powder is preferably 20 μm or less, for example. When it is 20 μm or less, the gaps in the aggregate can be easily impregnated.

  (7) The pyrolytic carbon coating has a thickness of 50 to 800 nm.

  If the thickness of the pyrolytic carbon coating is 800 nm or less, the combined thickness of the pyrolytic carbon coating and SiC fiber can be reduced, so the surface tension of the pyrolytic carbon coating generated when bent is reduced. It can be made small and difficult to break. When the thickness of the pyrolytic carbon coating is 50 nm or more, the SiC fiber and the SiC coating can be sufficiently separated from each other, thereby preventing a reduction in the reinforcing action of the SiC fiber by integrating the SiC fiber and the SiC coating. can do.

  (8) The thickness of the SiC coating is 0.5 to 10 μm.

  When the thickness of the SiC coating is 10 μm or less, the combined thickness of the SiC coating, the pyrolytic carbon coating and the SiC fiber can be reduced, so that the tension on the surface of the SiC coating generated when bent is reduced. And it can be made difficult to break. When the thickness of the SiC coating is 0.5 μm or more, the pyrolytic carbon coating and the SiC matrix can be sufficiently separated from each other, so that the metal silicon contained in the SiC matrix and the pyrolytic carbon coating can be separated. It is possible to prevent the pyrolytic carbon coating from becoming SiC. In addition, since the contact between the pyrolytic carbon coating and the metal silicon can be prevented in the manufacturing process, the pyrolytic carbon coating can be prevented from being converted to SiC.

  (9) The SiC fiber has a diameter of 5 to 20 μm.

  The SiC fiber contains oxygen inside. For this reason, when oxygen reacts and defects are formed, the ratio occupied in the cross-sectional area increases and the strength deteriorates. When the thickness is 5 μm or more, this influence can be reduced, and breakage can be made difficult. When the diameter of the SiC fiber is 20 μm or less, since the tension generated on the surface of the bent SiC fiber is small, it can be made difficult to break.

  The ceramic composite material of the present invention is as follows.

(10) A ceramic composite material comprising an aggregate in which SiC fibers containing oxygen are gathered and a Si matrix filling the space inside the aggregate, wherein the SiC fibers are covered with a CVD film containing carbon. ing.

A SiC-containing ceramic film is formed on the SiC fiber by a CVD method. The ceramic coating is a CVD coating. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon during the manufacturing process and use, it is decomposed into SiO and dissipated as a gas. In the ceramic composite material of the present invention, since the CVD coating containing carbon made of high-purity ceramic is formed, it is possible to prevent the metal silicon and SiO ₂ from coming into direct contact. For this reason, deterioration of a SiC fiber can be prevented.

Moreover, the ceramic composite material of the present invention for solving the above problems is
(11) A ceramic composite material comprising an aggregate in which SiC fibers containing oxygen are gathered and a SiC matrix filling the space inside the aggregate, wherein the SiC fibers are covered with a CVD film containing carbon. The SiC matrix is reaction sintered SiC.

Reaction-sintered SiC is SiC formed by the reaction of silicon and carbon. Since silicon is supplied by melting metal silicon, a dense SiC matrix can be obtained. Moreover, the CVD film which consists of ceramics is formed in SiC fiber. The CVD coating is a ceramic coating. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon at a high temperature during production and use, it decomposes into SiO, dissipates as a gas, and causes deterioration of the SiC fiber. In the ceramic composite material of the present invention, since the CVD coating containing carbon made of high-purity ceramic is formed, it is possible to prevent the metal silicon and SiO ₂ from coming into direct contact. For this reason, deterioration of a SiC fiber can be prevented.

  Furthermore, the ceramic composite material of the present invention is preferably in the following manner.

  (12) The SiC matrix contains metallic silicon.

  The SiC matrix containing metallic silicon indicates that the composition of the SiC matrix is silicon-rich. In this case, the SiC matrix is composed of metallic silicon and SiC, and all the carbon is bonded to silicon to form SiC. For this reason, there is no carbon that oxidizes and depletes even when used at high temperatures, and can be used stably.

  (13) The CVD coating is composed of a pyrolytic carbon coating covering the SiC fiber and a SiC coating covering the outside of the pyrolytic carbon coating.

  Since the SiC film formed by the CVD method can use a high-purity source gas such as a mixed gas of silane and hydrocarbon or an organic silane gas, it has a high purity and does not contain oxygen. For this reason, SiO gas is not generated even if it contacts with metallic silicon. Further, since the pyrolytic carbon coating is formed between the SiC coating and the SiC fiber, the SiC fiber and the SiC coating are not integrated, and the reinforcing action of the SiC fiber can be maintained.

  (14) The pyrolytic carbon coating has a thickness of 50 to 800 nm.

  If the thickness of the pyrolytic carbon coating is 800 nm or less, the combined thickness of the pyrolytic carbon coating and SiC fiber can be reduced, so the surface tension of the pyrolytic carbon coating generated when bent is reduced. It can be made small and difficult to break. When the thickness of the pyrolytic carbon coating is 50 nm or more, the SiC fiber and the SiC coating can be sufficiently separated from each other, thereby preventing the reduction of the reinforcing action of the SiC fiber due to the integration of the SiC fiber and the SiC coating. can do.

  (15) The thickness of the SiC coating is 0.5 to 10 μm.

  When the thickness of the SiC coating is 10 μm or less, the combined thickness of the SiC coating, the pyrolytic carbon coating and the SiC fiber can be reduced, so that the tension on the surface of the SiC coating generated when bent is reduced. And it can be made difficult to break. When the thickness of the SiC coating is 0.5 μm or more, the pyrolytic carbon coating and the SiC matrix can be sufficiently separated from each other, so that the metal silicon contained in the SiC matrix and the pyrolytic carbon coating can be separated. It is possible to prevent the pyrolytic carbon coating from becoming SiC. In addition, since the contact between the pyrolytic carbon coating and the metal silicon can be prevented in the manufacturing process, the pyrolytic carbon coating can be prevented from being converted to SiC.

  (16) The SiC fiber has a diameter of 5 to 20 μm.

  The SiC fiber contains oxygen inside. For this reason, when oxygen reacts and defects are formed, the ratio occupied in the cross-sectional area increases and the strength deteriorates. When the thickness is 5 μm or more, this influence can be reduced, and breakage can be made difficult. When the diameter of the SiC fiber is 20 μm or less, since the tension generated on the surface of the bent SiC fiber is small, it can be made difficult to break.

According to the method for producing a ceramic composite material of the present invention, an SiC fiber containing oxygen is aggregated to form an aggregate, and then placed in a CVD furnace to form a ceramic coating containing carbon on the surface of the SiC fiber, and silicon Impregnated and densified in the impregnation step. Further, a ceramic film is formed on the SiC fiber by a CVD method. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon during the manufacturing process and use, it is decomposed into SiO and dissipated as a gas. In the ceramic composite of the present invention, since a high-purity ceramic film is formed by the CVD method, the metal silicon and SiO ₂ can be prevented from coming into direct contact with each other, and the fiber itself can be prevented from deteriorating.

According to the ceramic composite material of the present invention, the ceramic composite material includes an aggregate in which SiC fibers containing oxygen are aggregated and a Si matrix that fills the space inside the aggregate, and the SiC fibers contain carbon. Covered with CVD coating. A SiC-containing ceramic film is formed on the SiC fiber by a CVD method. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon during the manufacturing process and use, it is decomposed into SiO and dissipated as a gas. Since the ceramic film containing high purity carbon is formed by the CVD method, the ceramic composite of the present invention can prevent direct contact between the metal silicon and SiO ₂ . For this reason, deterioration of a SiC fiber can be prevented.

According to the ceramic composite material of the present invention, the ceramic composite material includes an aggregate in which SiC fibers containing oxygen are gathered and a SiC matrix that fills the space inside the aggregate, and the SiC fibers contain carbon. Covered with a CVD coating, the SiC matrix is reactively sintered SiC. Reaction-sintered SiC is SiC formed by the reaction of silicon and carbon. Since silicon is supplied by melting metal silicon, a dense SiC matrix can be obtained. In addition, a ceramic film containing carbon is formed on the SiC fiber by a CVD method. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon during the manufacturing process and use, it is decomposed into SiO and dissipated as a gas. Since the ceramic film containing high purity carbon is formed by the CVD method, the ceramic composite of the present invention can prevent direct contact between the metal silicon and SiO ₂ . For this reason, deterioration of a SiC fiber can be prevented.

It is a flowchart which shows the manufacturing process of Embodiment 1 of the ceramic composite material of this invention. It is a flowchart which shows the manufacturing process of Embodiment 2 of the ceramic composite material of this invention. It is a flowchart which shows the manufacturing process of Embodiment 3 of the ceramic composite material of this invention. It is explanatory drawing which shows the manufacturing process of Embodiment 1 of the ceramic composite material of this invention. It is explanatory drawing which shows the manufacturing process of Embodiment 2 of the ceramic composite material of this invention. It is explanatory drawing which shows the manufacturing process of Embodiment 3 of the ceramic composite material of this invention. It is a scanning electron micrograph of the cross section of the ceramic composite material of an Example. It is a scanning electron micrograph of the cross section of the ceramic composite material of a comparative example.

(Detailed description of the invention)
In this specification, “metal silicon” means single silicon bonded with silicon.

  The method for producing a ceramic composite material according to the present invention includes an aggregate forming step of assembling oxygen-containing SiC fibers to form an aggregate, and a ceramic coating containing carbon on the surface of the SiC fibers by placing the aggregate in a CVD furnace. And a silicon impregnation step of impregnating the aggregate with silicon.

In the method for producing a ceramic composite material of the present invention, an SiC fiber containing oxygen is aggregated to form an aggregate, and then put into a CVD furnace to form a ceramic coating containing carbon on the surface of the SiC fiber, and a silicon impregnation step Impregnate with metal silicon and densify. A ceramic film containing carbon is formed on the SiC fiber containing oxygen by a CVD method. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon during the manufacturing process and use, it is decomposed into SiO, dissipates as a gas, and causes deterioration of the SiC fiber. In the ceramic composite of the present invention, a ceramic coating containing high-purity carbon is formed by the CVD method, so that direct contact between metal silicon and SiO ₂ can be prevented, and deterioration of the fiber itself is prevented. can do.

  The ceramic coating containing carbon includes a ceramic coating of pyrolytic carbon in addition to a carbide-based ceramic coating such as SiC, TaC, and WC. In addition, since the carbon-containing ceramic coating is a ceramic having high heat resistance, such as a carbide-based ceramic and pyrolytic carbon, and is formed by a CVD method, a dense coating can be obtained. For this reason, it is difficult to react with molten silicon, and deterioration of SiC fiber containing oxygen can be prevented. In particular, the outermost surface of the ceramic coating is preferably a carbide ceramic. Carbide-based ceramics can be suitably used because of their low reactivity with molten silicon.

  In the method for producing a ceramic composite of the present invention, the carbon-containing ceramic coating is composed of a pyrolytic carbon coating covering SiC fibers and a SiC coating covering the outside of the pyrolytic carbon coating.

  The SiC coating formed by the CVD method of the method for producing a ceramic composite of the present invention can use a high-purity source gas such as a mixed gas of silane and hydrocarbons or an organic silane gas, and thus has a high purity and contains oxygen. Not done. For this reason, SiO gas is not generated even if it contacts with metallic silicon. Further, since the pyrolytic carbon coating is formed between the SiC coating and the SiC fiber, the SiC fiber and the SiC coating are not integrated, and the reinforcing action of the SiC fiber can be maintained.

  The method for producing a ceramic composite material according to the present invention includes a carbon precursor impregnation step in which an aggregate is impregnated with a carbon precursor and a heat treatment of the aggregate between the CVD step and the silicon impregnation step. And a heat treatment step for forming a carbon matrix.

  In the method for producing a ceramic composite material of the present invention, oxygen-containing SiC fibers are aggregated to form an aggregate, and then put into a CVD furnace to form a ceramic coating containing carbon on the surface of the SiC fiber, and then the bone The material is impregnated with a carbon precursor and heat treated to form a carbon matrix. Silicon expands by nearly 10% as it solidifies. For this reason, it is easy to generate a strong tension on the SiC fiber by volume expansion. By forming a carbon matrix inside the aggregate, the amount of silicon impregnated can be reduced, volume expansion due to solidification can be suppressed, tension applied to SiC fibers can be reduced, and the strength of the ceramic composite can be increased. it can.

  The method for producing a ceramic composite of the present invention further includes a firing step of firing the aggregate and reacting the carbon matrix with silicon to form SiC after the silicon impregnation step.

  In the method for producing a ceramic composite material of the present invention, since the silicon silicon and the carbon matrix are reacted to form SiC by firing, a heat-resistant temperature is increased, and a ceramic composite material that can be stably used is resistant to thermal deformation. Can be formed.

  In the manufacturing method of the ceramic composite material of this invention, the processing temperature of a baking process is 1410-1600 degreeC.

  In the method for producing a ceramic composite material of the present invention, since the treatment temperature in the firing step is 1600 ° C. or less, the deterioration of the SiC fiber can be suppressed, and the treatment temperature in the firing step is 1410 ° C. or more. The reaction between the matrix and the metal silicon can be sufficiently performed.

  In the method for producing a ceramic composite of the present invention, the carbon precursor is at least one carbon precursor selected from pitch, a copna resin, a phenol resin, and a carbon powder dispersion.

  The carbon precursor of the method for producing a ceramic composite of the present invention may be any carbon precursor that can be carbonized by heat treatment. For example, in addition to organic substances such as pitch, copna resin, and phenol resin, a dispersion of carbon powder made of a solvent and carbon powder may be used. The organic matter is decomposed and carbonized by heat treatment, and in the dispersion of carbon powder, the solvent is volatilized by heat treatment and the carbon powder remains. In either case, since a part of the carbon precursor is removed, pores are formed, and silicon can be taken into the pores in the silicon impregnation step. When organic substances are used, the carbon matrices are integrated with each other, whereas when carbon powder is used, the carbon powder exists as discrete particles that are not bonded to each other. In this case, the separated particles can be fixed by the silicon impregnated in the subsequent silicon impregnation step.

  Further, organic substances such as pitch, copna resin, phenol resin, and carbon powder may be used at the same time. When the carbon powder and the organic substance are used at the same time, the yield of carbonization is high, and the amount of remaining metal silicon can be reduced.

  Any carbon powder may be used. For example, carbon cracks, coke powder, amorphous coke powder, graphite powder and the like can be used. The 50% volume cumulative diameter of the carbon powder is preferably 20 μm or less, for example. When it is 20 μm or less, the gaps in the aggregate can be easily impregnated.

  In the method for producing a ceramic composite of the present invention, the pyrolytic carbon coating has a thickness of 50 to 800 nm.

  In the method for producing a ceramic composite material of the present invention, since the pyrolytic carbon coating has a thickness of 800 nm or less, the combined thickness of the pyrolytic carbon coating and SiC fibers can be reduced. Accordingly, it is possible to reduce the surface tension of the pyrolytic carbon film that is generated when bent, and to make it difficult to break. Since the thickness of the pyrolytic carbon coating is 50 nm or more, the SiC fiber and the SiC coating can be sufficiently separated from each other, so that the SiC fiber and the SiC coating are integrated to reduce the reinforcing action of the SiC fiber. Can be prevented.

  In the manufacturing method of the ceramic composite material of this invention, the thickness of a SiC film is 0.5-10 micrometers.

  In the method for producing a ceramic composite of the present invention, since the thickness of the SiC coating is 10 μm or less, the combined thickness of the SiC coating, the pyrolytic carbon coating, and the SiC fiber can be reduced and bent. It is possible to reduce the tension of the surface of the SiC coating that is sometimes generated and to make it difficult to break. Since the thickness of the SiC coating is 0.5 μm or more, the pyrolytic carbon coating and the SiC matrix can be sufficiently separated, and the metal silicon contained in the SiC matrix and the pyrolytic carbon coating can be separated, It is possible to prevent the pyrolytic carbon coating from becoming SiC. In addition, since the contact between the pyrolytic carbon coating and the metal silicon can be prevented in the manufacturing process, the pyrolytic carbon coating can be prevented from becoming SiC.

  In the manufacturing method of the ceramic composite material of this invention, the diameter of a SiC fiber is 5-20 micrometers.

  The SiC fiber contains oxygen inside. For this reason, when oxygen reacts and defects are formed, the ratio occupied in the cross-sectional area increases and the strength deteriorates. In the method for producing a ceramic composite material of the present invention, since the SiC fiber has a diameter of 5 μm or more, this influence can be reduced and it is difficult to break. Since the diameter of the SiC fiber is 20 μm or less, since the tension generated on the surface of the bent SiC fiber is small, it can be made difficult to break.

  The ceramic composite material of the present invention is a ceramic composite material composed of an aggregate in which SiC fibers containing oxygen are aggregated and a Si matrix that fills the space inside the aggregate, and the SiC fiber is a CVD coating containing carbon. Covered with.

A SiC-containing ceramic film is formed on the SiC fiber by a CVD method. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon during the manufacturing process and use, it is decomposed into SiO and dissipated as a gas. In the ceramic composite material of the present invention, since the CVD coating containing carbon made of high-purity ceramic is formed, it is possible to prevent the metal silicon and SiO ₂ from coming into direct contact. For this reason, deterioration of a SiC fiber can be prevented.

  The ceramic composite of the present invention is a ceramic composite comprising an aggregate in which SiC fibers containing oxygen are gathered and a SiC matrix that fills the space inside the aggregate, the SiC fibers being a CVD coating containing carbon And the SiC matrix is reaction-sintered SiC.

Reaction-sintered SiC is SiC formed by the reaction of metal silicon and carbon. Since silicon is supplied by melting silicon, a dense SiC matrix can be obtained. Further, a CVD film containing carbon made of ceramic is formed on the SiC fiber. Originally, SiC fiber contains a trace amount of oxygen derived from raw materials. Oxygen is contained in the form of SiO _2. When SiO ₂ comes into contact with metallic silicon during the manufacturing process and use, it is decomposed into SiO, dissipates as a gas, and causes deterioration of the SiC fiber. In the ceramic composite material of the present invention, since the CVD coating containing carbon made of high-purity ceramic is formed, it is possible to prevent the metal silicon and SiO ₂ from coming into direct contact. For this reason, deterioration of a SiC fiber can be prevented.

  Furthermore, the ceramic composite of the present invention contains metallic silicon in the SiC matrix.

  The SiC matrix containing metallic silicon indicates that the composition of the SiC matrix is silicon-rich. In this case, the SiC matrix is composed of metallic silicon and SiC, and all the carbon is bonded to silicon to form SiC. For this reason, there is no carbon that oxidizes and depletes even when used at high temperatures, and can be used stably.

  In the ceramic composite of the present invention, the CVD coating is composed of a pyrolytic carbon coating covering the SiC fiber and a SiC coating covering the outside of the pyrolytic carbon coating.

  Since the SiC film formed by the CVD method of the ceramic composite material of the present invention can use a high-purity raw material gas such as a mixed gas of silane and hydrocarbon or an organic silane gas, it has a high purity and does not contain oxygen. . For this reason, SiO gas is not generated even if it contacts with metallic silicon. Further, since the pyrolytic carbon coating is formed between the SiC coating and the SiC fiber, the SiC fiber and the SiC coating are not integrated, and the reinforcing action of the SiC fiber can be maintained.

  In the ceramic composite of the present invention, the pyrolytic carbon coating has a thickness of 50 to 800 nm.

  Since the thickness of the pyrolytic carbon coating of the ceramic composite of the present invention is 800 nm or less, the combined thickness of the pyrolytic carbon coating and SiC fibers can be reduced, and pyrolytic carbon generated when bent. The tension on the surface of the coating can be reduced, making it difficult to break. Since the thickness of the pyrolytic carbon coating is 50 nm or more, the SiC fiber and the SiC coating can be sufficiently separated, and the reduction of the reinforcing action of the SiC fiber due to the integration of the SiC fiber and the SiC coating is prevented. be able to.

  In the ceramic composite of the present invention, the thickness of the SiC coating is 0.5 to 10 μm.

  Since the thickness of the SiC coating of the present invention is 10 μm or less, the combined thickness of the SiC coating, the pyrolytic carbon coating, and the SiC fiber can be reduced, and the SiC produced when bent The tension on the surface of the coating can be reduced, making it difficult to break. Since the thickness of the SiC coating is 0.5 μm or more, the pyrolytic carbon coating and the SiC matrix can be sufficiently separated, and the metal silicon contained in the SiC matrix and the pyrolytic carbon coating can be separated, It is possible to prevent the pyrolytic carbon coating from becoming SiC. In addition, since the contact between the pyrolytic carbon coating and the metal silicon can be prevented in the manufacturing process, the pyrolytic carbon coating can be prevented from becoming SiC.

  The ceramic composite material of the present invention has a SiC fiber diameter of 5 to 20 μm.

  The SiC fiber contains oxygen inside. For this reason, when oxygen reacts and defects are formed, the ratio occupied in the cross-sectional area increases and the strength deteriorates. In the ceramic composite material of the present invention, since the SiC fiber has a diameter of 5 μm or more, this influence can be reduced and it can be made difficult to break. Since the diameter of the SiC fiber is 20 μm or less, since the tension generated on the surface of the bent SiC fiber is small, it can be made difficult to break.

The SiC fiber used for the ceramic composite of the present invention is manufactured using polycarbosilane containing oxygen as a raw material. In the process of production, a crosslinking reaction is required, and crosslinking is performed using an electron beam, oxygen, or the like. When oxygen cross-linking is performed, the content of oxygen contained in the SiC fiber is further increased. In the SiC fiber by electron beam crosslinking without oxygen crosslinking, for example, the oxygen content is 0.5 to 1.0% by weight, and in the SiC fiber by oxygen crosslinking, for example, the oxygen content is 1.0 to 20% by weight. The oxygen content in the SiC fiber of the ceramic composite of the present invention and the method for producing the ceramic composite is, for example, 0.5 to 20% by weight. Oxygen is contained in the SiO ₂ form. Whichever cross-linked SiC fiber is used, SiO ₂ easily reacts with molten silicon, and the SiC fiber is eroded by the reaction.

On the other hand, the ceramic coating by the CVD method does not require a sintering aid or the like as a raw material, so that a high purity ceramic coating can be obtained. A high-purity ceramic coating does not easily react with molten silicon, and therefore can be less likely to be eroded. In particular, the SiC film formed by the CVD method does not contain oxygen in the raw material gas, and the oxygen mixing path has only contamination from the apparatus, so the oxygen content is extremely small. For this reason, the content of SiO ₂ is extremely small, and there is almost no influence on erosion. For example, the oxygen content of the SiC film formed by the CVD method is 10 ppm by weight or less even if mixed.

  The form of the aggregate used for the ceramic composite of the present invention is not particularly limited. For example, cloths, papermaking bodies, filament winding bodies, braiding bodies, etc. can be used.

The cloth is woven using a strand in which SiC fibers are bundled. The papermaking body is manufactured using SiC short fibers and long fibers. The filament winding body is formed by winding a strand in which SiC fibers are bundled around a mandrel. The angle of winding around the mandrel can be determined by any method such as hoop winding where the strands are in contact with or adjacent to each other, helical winding winding diagonally at large intervals. Also good.
The braided body forms a cylindrical aggregate by knitting strands in opposite directions.

  Although the number of SiC fiber used for one strand of the ceramic composite material of this invention is not specifically limited, For example, it is 100-5000 pieces.

(Mode for carrying out the invention)
Embodiments 1 to 3 of the present invention will be described in order with reference to the drawings.

<Embodiment 1>
FIG. 1 is a flowchart showing the manufacturing process of the first embodiment of the ceramic composite material of the present invention. FIG. 4 is an explanatory view showing a manufacturing process of the first embodiment of the ceramic composite material of the present invention.

  The manufacturing method of the ceramic composite material 10 according to the first embodiment includes an aggregate forming step (P1) in which the SiC fibers 1 containing oxygen are aggregated to form the aggregate 9, and the aggregate 9 is placed in a CVD furnace. 1 includes a CVD process (P2) for forming the ceramic coating 2 on the surface of 1 and a silicon impregnation process (P3) for impregnating the aggregate 9 with silicon.

  A ceramic composite material 10 comprising an aggregate 9 in which SiC fibers 1 containing oxygen are gathered by such a manufacturing method and an Si matrix 3 filling a space inside the aggregate, the SiC fiber 1 containing carbon The ceramic composite material of the present invention covered with the CVD film (ceramic film) 2 can be obtained.

  In the present embodiment, since the SiC fiber 1 containing oxygen and the Si matrix 3 are not in direct contact with each other, the SiC fiber 1 is not subject to erosion by silicon and is not deteriorated during manufacture and use, and thus has high strength. A ceramic composite material 10 can be obtained.

<Embodiment 2>
FIG. 2 is a flowchart showing the manufacturing process of the second embodiment of the ceramic composite material of the present invention. FIG. 5 is an explanatory view showing a manufacturing process of the second embodiment of the ceramic composite material of the present invention.

  The method for manufacturing ceramic composite material 10 of the second embodiment includes an aggregate forming step (P1) in which SiC fibers 1 containing oxygen are aggregated to form aggregate 9, and aggregate 9 is placed in a CVD furnace, and SiC fibers CVD process (P2) for forming a ceramic coating 2 containing carbon on the surface of 1, carbon precursor impregnation process (P4) for impregnating aggregate 9 with carbon precursor 7, heat treatment of aggregate 9, carbon It includes a heat treatment step (P5) for carbonizing the precursor 7 to make the carbon matrix 5, and a silicon impregnation step (P3) for impregnating the aggregate 9 with silicon.

  By such a manufacturing method, the ceramic composite material 10 is composed of the aggregate 9 in which the SiC fibers 1 containing oxygen are gathered and the Si matrix 3 that fills the space inside the aggregate, and the SiC fiber 1 contains carbon. The ceramic composite material 10 covered with the contained CVD film 2 can be obtained. In this way, the ceramic composite material 10 of the present invention can be obtained. The Si matrix 3 contains carbon.

  In the present embodiment, since the Si matrix 3 contains carbon in advance, the content of metal silicon can be reduced. For this reason, the influence of volume expansion of the Si matrix 3 when silicon is solidified can be reduced, damage to the SiC fiber 1 can be reduced, and a high-strength ceramic composite material 10 can be provided.

<Embodiment 3>
FIG. 3 is a flowchart showing the manufacturing process of the third embodiment of the ceramic composite material of the present invention. FIG. 6 is an explanatory view showing the manufacturing process of the third embodiment of the ceramic composite material of the present invention.

  The method for manufacturing ceramic composite material 10 according to the third embodiment includes an aggregate formation step (P1) in which SiC fibers 1 containing oxygen are aggregated to form aggregate 9, and aggregate 9 is placed in a CVD furnace. CVD process (P2) for forming a ceramic coating 2 containing carbon on the surface of 1, carbon precursor impregnation process (P4) for impregnating aggregate 9 with carbon precursor 7, heat treatment of aggregate 9, carbon A heat treatment step (P5) for carbonizing the precursor 7 to make the carbon matrix 5, a silicon impregnation step (P3) for impregnating the aggregate 9 with silicon, and firing the aggregate 9 to react the carbon matrix 5 with metallic silicon And a baking step (P6) for converting to SiC.

  In the aggregate forming step (P1), for example, a strand in which 100 to 5000 SiC fibers 1 are bundled is wound around a mandrel, and an aggregate 9 of a filament winding body is obtained.

  In the CVD process (P2), for example, methane is first introduced, and then methane and trichlorosilane are introduced as source gases, and the CVD coating (ceramic coating) 2 containing carbon covering the SiC fiber 1 has pyrolytic carbon inside. Further, a CVD film 2 having a two-layer structure of SiC on the outside of pyrolytic carbon can be obtained.

  Next, the filament winding body is removed from the mandrel, and impregnated with, for example, a phenol resin in the carbon precursor impregnation step (P4). As the phenol resin, those dissolved in an organic solvent or water, those melted by heat, and the like can be used.

  In the heat treatment step (P5), the aggregate 9 impregnated with the carbon precursor 7 is placed in a heat treatment furnace and heated. The heat treatment furnace is processed in an inert atmosphere or in a vacuum. When a solvent is contained, the solvent is first volatilized. Therefore, heat treatment can be efficiently performed by increasing the rate of temperature rise after the volatilization of the solvent is completed. A desirable heat treatment temperature is 600 to 1200 ° C. If the heat treatment temperature is 600 ° C. or higher, the carbon precursor 7 can be sufficiently carbonized, and if the heat treatment temperature is 1200 ° C. or lower, the deterioration of the SiC fiber 1 in the heat treatment step can be reduced. .

  In the heat treatment step (P5), a large amount of decomposition gas is generated in the process of decomposition of the carbon precursor 7 and an outflow path of the decomposition gas is secured, so that the volume of pores formed in the carbon matrix 5 is increased. In the silicon impregnation process, silicon penetrates into the pores. For this reason, silicon becomes surplus with respect to the carbon matrix, and surplus silicon remains after the reaction.

  Next, in the silicon impregnation step (P3), the obtained aggregate is immersed in molten silicon. Silicon can be impregnated in a short time by previously melting and immersing silicon. Although the temperature of molten silicon is not specifically limited, For example, it is 1410-1600 degreeC.

  Next, in the firing step (P6), the aggregate 9 impregnated with silicon is fired, carbon and silicon are reacted to form reactive sintered SiC, and the SiC matrix 4 can be obtained. The temperature of baking is 1410-1600 degreeC.

  By such a manufacturing method, the ceramic composite material 10 is composed of the aggregate 9 in which the SiC fibers 1 containing oxygen are gathered and the SiC matrix 4 that fills the space inside the aggregate, and the SiC fiber 1 contains carbon. The ceramic composite material 10 of the present invention, which is covered with the contained CVD film (ceramic film) 2 and the SiC matrix 4 is reaction-sintered SiC, can be obtained.

  In the present embodiment, since the carbon matrix 5 is formed and further impregnated with silicon and then baked, the carbon matrix 5 and silicon react to obtain a SiC matrix 4 made of reactively sintered SiC.

  In the present embodiment, since the CVD coating (ceramic coating) 2 containing carbon composed of the pyrolytic carbon coating and the SiC coating is formed on the surface of the SiC fiber 1 containing oxygen, the silicon impregnation step (P3) In the firing step (P6), the SiC fiber 1 is not deteriorated by silicon. In addition, since the pyrolytic carbon coating is provided between the SiC fiber 1 and the SiC coating, the effect of fiber reinforcement by the SiC fiber is sufficiently exhibited without the SiC fiber 1 and the SiC coating being integrated. Can do.

Examples of the present invention and comparative examples will be described below.
(Example)

<Aggregate formation process>
Five woven fabrics made of SiC fiber 1 are used as aggregate 9. The woven fabric is formed by weaving strands of 2000 bundles of SiC fibers 1 containing oxygen.

<CVD process>
Next, the aggregate 9 is put into a CVD furnace, methane is introduced at a treatment temperature of 1100 ° C., a pyrolytic carbon film is formed on the surface of the SiC fiber 1, and then methane and trichlorosilane are introduced at a treatment temperature of 1200 ° C. Then, an SiC film is formed.

<Silicon impregnation process>
The aggregate is impregnated with silicon. Silicon is melted in a quartz crucible and the temperature is 1450 ° C. Molten silicon has high wettability with SiC and a small contact angle, so that it can quickly penetrate into the interior. The immersion time is 10 minutes.

  The obtained ceramic composite material 10 was cut and the cross section was observed. FIG. 7 is a cross-sectional view of the obtained ceramic composite material.

  The obtained ceramic composite material 10 is composed of an aggregate in which SiC fibers 1 containing oxygen are gathered and an Si matrix 3 filling the space inside the aggregate, and the SiC fibers 1 are made of a CVD film 2 containing carbon. It was confirmed to be a covered ceramic composite.

  Although the oxygen content of the SiC fiber 1 used was 0.7%, the ceramic coating 2 did not contact the metal silicon, and the SiC fiber 1 was not eroded by the silicon.

(Comparative example)
A ceramic composite material was prepared in the same manner as in the example except that there was no CVD process. That is, the SiC fiber constituting the ceramic composite material does not have a CVD film containing carbon. The oxygen content of the SiC fiber used was similarly 0.7%.

  The obtained ceramic composite was cut and the cross section was observed. FIG. 8 is a sectional view of the obtained ceramic composite material.

  The obtained ceramic composite is a ceramic composite composed of an aggregate in which SiC fibers are aggregated and an Si matrix that fills the space inside the aggregate, but the SiC fibers do not have a CVD coating.

  The SiC fiber was in contact with the molten silicon, the cross-sectional shape of the SiC fiber having a circular cross section was changed, the cross-sectional shape was different for each SiC fiber, and erosion by silicon was confirmed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the matters shown in the above embodiments, and those skilled in the art will understand the scope of the claims and the description, and based on well-known techniques. Modifications or applications are also contemplated by the present invention and are within the scope of seeking protection.

1 SiC fiber 2 CVD coating (ceramic coating)
3 Si matrix 4 SiC matrix 5 Carbon matrix 7 Carbon precursor 9 Aggregate 10 Ceramic composite material

Claims (16)

A method for producing a ceramic composite, comprising:
An aggregate forming step of forming an aggregate by assembling SiC fibers containing oxygen;
CVD step of placing the aggregate in a CVD furnace and forming a ceramic coating containing carbon on the surface of the SiC fiber;
A silicon impregnation step of impregnating the aggregate with silicon;
A method for producing a ceramic composite material comprising:   2. The method for producing a ceramic composite material according to claim 1, wherein the ceramic coating includes a pyrolytic carbon coating covering the SiC fiber and a SiC coating covering the outside of the pyrolytic carbon coating. Between the CVD step and the silicon impregnation step,
A carbon precursor impregnation step of impregnating the aggregate with a carbon precursor;
A heat treatment step of heat treating the aggregate and carbonizing the carbon precursor into a carbon matrix;
The method for producing a ceramic composite material according to claim 1, further comprising: After the silicon impregnation step,
The method for producing a ceramic composite material according to claim 3, further comprising a firing step of firing the aggregate and reacting the carbon matrix with the silicon to form SiC.   The method for producing a ceramic composite material according to claim 4, wherein the firing step has a processing temperature of 1410 to 1600 ° C.   The method for producing a ceramic composite material according to any one of claims 3 to 5, wherein the carbon precursor is at least one carbon precursor selected from a dispersion of pitch, copna resin, phenol resin, and carbon powder.   The method for producing a ceramic composite according to claim 2, wherein the pyrolytic carbon coating has a thickness of 50 to 800 nm.   The method for producing a ceramic composite material according to claim 2, wherein the SiC coating has a thickness of 0.5 to 10 μm.   The method for producing a ceramic composite material according to claim 1, wherein the SiC fiber has a diameter of 5 to 20 μm. A ceramic composite material including an aggregate in which SiC fibers containing oxygen are aggregated, and an Si matrix filling a space inside the aggregate,
The SiC fiber is a ceramic composite material covered with a CVD film containing carbon. A ceramic composite material including an aggregate in which SiC fibers containing oxygen are aggregated, and a SiC matrix filling a space inside the aggregate,
The SiC fiber is covered with a CVD film containing carbon;
The SiC matrix is a ceramic composite material in which reaction-sintered SiC is used.   The ceramic composite according to claim 11, wherein the SiC matrix contains metallic silicon.   The ceramic composite material according to any one of claims 10 to 12, wherein the CVD coating includes a pyrolytic carbon coating that covers the SiC fiber and a SiC coating that covers the outside of the pyrolytic carbon coating.   The ceramic composite material according to claim 13, wherein the pyrolytic carbon coating has a thickness of 50 to 800 nm.   The ceramic composite material according to claim 13 or 14, wherein the SiC coating has a thickness of 0.5 to 10 µm.   The ceramic composite material according to any one of claims 10 to 15, wherein the SiC fiber has a diameter of 5 to 20 µm.