Method for manufacturing oxide-based ceramic matrix composites using zirconia continuous fibers as reinforcing fibers.

Abstract

To provide a method for producing a composite material excellent in heat resistance and environmental resistance by using zirconia-based ceramics as a matrix using a zirconia continuous fiber of improved high heat resistance as a reinforcing material.SOLUTION: A method for producing a zirconia continuous fiber-reinforced zirconia-based ceramic matrix composite material comprises: a first step of providing at least one kind of fiber bundle, two-dimensional fabric, or three-dimensional fabric obtained by coating zirconia continuous fiber with carbon to provide a composite material excellent in heat resistance and environmental resistance using zirconia-based ceramics as a matrix using zirconia continuous fiber as a reinforcing material having improved heat resistance; a second step of preparing a slurry of zirconia-based ceramic powder with water or a zirconia-based ceramic precursor solution; a third step of preparing a prepreg by coating or impregnating the slurry onto the fiber bundle, two-dimensional fabric, or three-dimensional fabric; a fourth step of drying the prepreg or drying the prepreg after gelation; and a fifth step of densification by a PIP process.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an oxide-based ceramic matrix composite material, and particularly to a method for manufacturing a composite material having excellent heat resistance and environmental resistance, with a zirconia-based ceramic as a matrix and an improved high heat-resistant zirconia continuous fiber as a reinforcing material.

Background Art

[0002] Regarding energy supply and demand, due to the soaring energy prices, there is a demand for the renewal of power generation facilities that can achieve improved thermal efficiency. In particular, in Japan, due to the suspension of operation of nuclear power plants caused by the Great East Japan Earthquake, it is necessary to enhance power generation facilities using thermal power plants and natural energy as alternative energy measures, and the renewal of power generation facilities that can achieve improved thermal efficiency has become economically reasonable. Furthermore, as seen in the Kyoto Protocol, there is a demand for reducing carbon dioxide emissions from the perspective of global environmental protection.

[0003] In response to such social demands for improving the thermal efficiency of power generation facilities and reducing carbon dioxide emissions, for example, gas turbine combined power generation is expected to have long-term market expansion as the cleanest and most economical thermal power generation facility that coexists with natural energy and nuclear power generation. Thus, micro gas turbines were initially introduced as distributed power sources in the 1990s, and since then, many manufacturers have entered the market. Many advantages such as simple structure, excellent load fluctuation characteristics, easy maintenance, and small environmental impact have been recognized. However, unlike large gas turbines for power generation, the combustion chamber outlet temperature is low because the inside of the turbine cannot be cooled, and the power generation efficiency is as low as about 28% at maximum, so the market scale has not expanded. In this context, ceramic matrix composites (CMCs) have already been put into practical use in jet engines as SiC fiber-reinforced SiC matrix CMCs, achieving significant improvements in fuel efficiency. While this material has good high-temperature strength, its environmental resistance is limited (it oxidizes), so its usable temperature is limited to around 1300°C. On the other hand, alumina matrix / alumina fiber composites have been put into practical use as oxide-based CMCs with excellent environmental resistance, but their high-temperature strength is low, so their usable temperature is even lower than that of SiC / SiC composites, posing a challenge in that they cannot be used for the target applications.

[0004] For example, as described in Non-Patent Document 1, "When a 1700°C class gas turbine is put into practical use as the main engine of a combined cycle power generation facility, the power generation efficiency will exceed 62% (based on lower heating value), representing a significant efficiency improvement over conventional thermal power generation facilities. For example, assuming that the thermal efficiency of a 1.25 million kW coal-fired power plant is 44% (based on lower heating value), the annual CO2 emissions will be 8.53 million tons. If this is replaced with a natural gas-fired 1700°C class combined cycle power generation facility, the CO2 emissions will be 3.24 million tons, a reduction of 62%." Therefore, developing heat-resistant materials that can be used in natural gas-fired 1700°C class combined cycle power generation facilities is of great significance.

[0005] In light of these circumstances, in 1700°C class gas turbines, metal materials are used as turbine blades for power generation turbine engines. However, since the combustion temperature itself is above the melting point of the metal material, it is essential to cool the material with air, steam, etc., to lower the material temperature. Even so, the material temperature still reaches a maximum of about 900°C, so properties such as creep strength, toughness, thermal fatigue characteristics, high-cycle fatigue characteristics, oxidation resistance, and corrosion resistance are necessary. Furthermore, in 1800°C class gas turbines, even if cooling is performed, the metal temperature rises even further, so creep strength, toughness, and oxidation resistance become the most fundamentally important properties. Conventional 1500°C class gas turbines employ ductile / brittle multiphase materials that combine a solid solution phase rich in ductility and toughness with an intermetallic compound phase with excellent high-temperature strength to simultaneously provide creep strength and toughness. Ni-based superalloys are a typical example and one of the best heat-resistant materials. However, in 1800°C class gas turbines, using these Ni-based superalloys requires significantly lowering the material temperature from 1800°C through extreme cooling. This results in substantial energy loss and prevents the achievement of the target efficiency improvements. Therefore, there is a need for materials with high strength and environmental resistance at ultra-high temperatures that do not require or only require minimal cooling for gas turbines operating at combustion temperatures of 1700°C to 1800°C.

[0006] Among heat-resistant materials that have attracted attention as materials that can be used even at high temperatures that are difficult for metals to handle, there are SiC fiber / SiC matrix composites, which are a type of ceramic matrix composite (CMC). As mentioned above, so-called SiC / SiC composites have been put into practical use in jet engines and have achieved a significant improvement in fuel efficiency. However, although these SiC / SiC composites have high high-temperature strength, they have limitations in environmental resistance, and oxidation proceeds easily at ultra-high temperatures, so until now the maximum usable temperature has been limited to around 1400°C. In other words, they were unsuitable as materials that could be used with no cooling or only slight cooling in gas turbines with target combustion temperatures of 1700°C to 1800°C. On the other hand, oxide ceramics are materials that inherently possess superior resistance to ultra-high temperatures. In other words, since the oxide has already been oxidized, further oxidation will not occur. Examples of ceramic matrix composite materials based on this oxide include those in which an alumina matrix is ​​impregnated between two-dimensionally woven mullite fibers, as proposed in Patent Document 1 by the present applicant. However, although this material has good environmental resistance (oxidation resistance), its high-temperature strength is insufficient, and its heat resistance temperature is limited to around 1100°C.

[0007] Zirconia is known as an oxide material with high high-temperature strength. Furthermore, Patent Document 2 proposes an oxide-based ceramic fiber / oxide-based ceramic composite material, in which zirconia is proposed as the main metal oxide component of the ceramic fiber. However, the applications for gas turbine engine components are merely an abstract list, and no material capable of withstanding combustion temperatures of 1700°C to 1800°C in gas turbines has been presented. Therefore, the inventors diligently conducted research to resolve the above-mentioned problems. Specifically, the objective of the research was to provide a ceramic matrix composite material for use in gas turbines with combustion temperatures of 1700°C to 1800°C, in particular, a ceramic matrix composite material in which a ceramic matrix with high heat resistance and environmental resistance is reinforced with ceramic fibers that also have high heat resistance and environmental resistance. Furthermore, the inventors provided stabilized zirconia continuous fibers or partially stabilized zirconia continuous fibers and a method for manufacturing the same, which can be used in zirconia fiber reinforced zirconia composite materials (Patent Document 3), and further proposed a method for manufacturing a composite material having a zirconia-based matrix using these fibers (Patent Document 4). According to this method for manufacturing a ceramic matrix composite material, a zirconia continuous fiber / BaZrO3 matrix composite material can be manufactured, and this material is said to be able to withstand use in gas turbines with combustion temperatures of 1700°C to 1800°C.

[0008] However, the properties actually evaluated were the shape retention and weight change of the appearance during ultra-high temperature atmospheric oxidation tests, and the compressive strength at 1800°C; the mechanical properties of the composite material itself were not evaluated. Furthermore, because the diameter of the reinforcing fibers is large and it has poor processability into woven fabrics, the strength of the composite material itself cannot be expected. Therefore, it was developed to be used as a composite structure by being bonded to ceramic, glass-ceramic, or carbon structures. Consequently, the composite material itself had the problem of not being able to withstand use in gas turbines with combustion temperatures of 1700°C to 1800°C. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] WO2012 / 077787A1 [Patent Document 2] Japanese Patent Publication No. 2002-173376 [Patent Document 3] Patent No. 6238286 [Patent Document 4] Patent No. 6327512 [Non-patent literature]

[0010] [Non-Patent Document 1] Mitsubishi Heavy Industries Technical Report, Vol. 47 (2010), No. 1, pp. 25-30 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] Therefore, the present invention aims to solve the above-mentioned problems and, with regard to ceramic matrix composite materials with a higher maximum operating temperature than SiC / SiC composite materials, to provide a method for manufacturing a high-toughness, high-strength ceramic matrix composite material in which a ceramic matrix with high heat resistance and environmental resistance is reinforced with ceramic fibers that also have high heat resistance and environmental resistance. Here, although SiC / SiC composite materials have high high-temperature strength, they have limitations in environmental resistance, and oxidation proceeds easily at ultra-high temperatures, so until now the maximum usable temperature has been limited to about 1400°C. [Means for solving the problem]

[0012] The present invention provides a method for producing a ceramic matrix composite material, for example, as shown in Figure 1, by coating zirconia continuous fibers with carbon. ru two dimensional or three-dimensional The first step is to provide at least one type of fabric; the second step is to prepare a slurry by mixing fine-grained BaZrO3 powder or zirconia-based ceramic powder with water or a solution of zirconia-based ceramic precursor dissolved in an organic solvent in a predetermined proportion; and the slurry is fabric A third step involves coating or impregnating to prepare a prepreg, and a fourth step involves removing water or organic solvents while adding slurry or precursor solution to the prepreg as needed, and drying or gelling and then drying, and drying at room temperature without oxidation. sex The process comprises a fifth step of producing a preform by primary firing in an atmosphere at a predetermined heating rate to a predetermined temperature, further impregnating it with a precursor solution after firing to gel it, repeating the firing process to densify it, and a sixth step of secondary firing in air or a non-oxidizing atmosphere, with the temperature at which the composite material will be used as the maximum heating temperature.

[0013] The present invention provides a method for manufacturing a ceramic matrix composite material, comprising a ceramic matrix made of a material with high heat resistance and environmental resistance, i.e., a zirconia-based ceramic matrix, and reinforcing fibers made of zirconia-based continuous fibers coated with carbon, which also have high heat resistance and environmental resistance. The composite material is highly tough and strong due to the function of the carbon interface layer. The ceramic matrix is ​​made of BaZrO3 or zirconia-based ceramics, and the reinforcing material is made of zirconia continuous fibers with improved heat resistance. In the method for producing the ceramic matrix composite material of the present invention, preferably, the BaZrO3 is a fine powder with an average particle size of about 1 μm or less, and the zirconia-based ceramic powder is also a fine powder with an average particle size of about 1 μm or less, and stabilized or partially stabilized zirconia is preferred. Furthermore, it is desirable to impregnate these fine powders with a precursor polymer synthesized by the co-hydrolysis condensation of zirconia and a metal oxide such as yttria, which generates stabilized zirconia by firing, because this promotes sintering after firing. The ceramic matrix composite material of the present invention maintains high toughness at the temperature in which it is used by utilizing a gap interface layer, which is created by burning off the carbon interface layer through secondary firing. [Effects of the Invention]

[0014] According to the method for manufacturing the ceramic-based composite material of the present invention, a zirconia continuous fiber / BaZrO3 matrix composite material or a zirconia continuous fiber / zirconia matrix-based composite material can be manufactured. Therefore, the manufactured ceramic-based composite material is suitable as a high-toughness and high-strength composite material having a higher maximum service temperature than the SiC / SiC composite material, whose maximum serviceable temperature has been about 1400°C.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 is a flowchart for explaining the method for manufacturing the ceramic-based composite material of the present invention. [Figure 2] FIG. 2 is a schematic diagram of an apparatus for performing the hexane bubble flow method for coating carbon on fibers. [Figure 3] FIG. 3 is a SEM photograph of a cross-section of a fiber showing the thickness of the carbon coating. [Figure 4] FIG. 4 is a stress-strain curve of the bending test of CMC(ZB)-5 of 1D-CMC, showing that fiber pull-out occurs at the time of fracture. [Figure 5] FIG. 5 is a SEM photograph showing fiber pull-out at the forced fracture surface after the bending test of CMC(ZB)-5 of 1D-CMC. [Figure 6] FIG. 6 is a SEM photograph of the forced fracture surface of CMC(ZB)-15 of 1D-CMC, showing the formation of a gap interface layer between the fiber and the matrix. [Figure 7] FIG. 7 is a SEM photograph of the forced fracture surface of CMC(ZB)-15 of 1D-CMC, showing the formation of a gap interface layer between the fiber and the matrix.

Embodiments for Carrying Out the Invention

[0016] The present invention will be specifically described below. Regarding '~' indicating a numerical range, it indicates the numerical range between the lower limit value and the upper limit value, and in this specification, unless otherwise specified, it represents the range from the lower limit value or more to the upper limit value or less. Figure 1 is a flowchart illustrating the method for manufacturing an oxide-based ceramic matrix composite material using zirconia continuous fibers as reinforcing fibers according to the present invention. The flowchart describes the method for manufacturing a composite material consisting of zirconia continuous fibers / BaZrO3 matrix and zirconia continuous fibers / zirconia-based ceramic as ceramic matrix composite materials.

[0017] First, a continuous zirconia fiber bundle, a two-dimensional fabric made by knitting a continuous zirconia fiber bundle in two dimensions, or a three-dimensional fabric made by knitting a continuous zirconia fiber bundle in three dimensions is prepared (S102). Next, carbon is coated onto the continuous zirconia fiber bundle, fabric, or three-dimensional fabric (S104, first step). This zirconia fiber bundle, two-dimensional fabric, or three-dimensional fabric can be made by bundling a predetermined number of continuous zirconia fiber bundles together or by knitting them using existing technology. The volume content V of the zirconia fiber in the composite material. f , or mass content M f This can be controlled to be less than 40% of the apparent total volume or total mass (fibers + matrix) of the composite material produced. The average diameter of zirconia continuous fibers is, for example, about 10-20 μm. The procedure for producing zirconia continuous fibers with improved heat resistance will be explained later.

[0018] Next, a slurry is prepared by blending BaZrO3 or zirconia-based ceramic fine particles in a predetermined proportion (S106, second step). The fine particles refer to BaZrO3 as a fine powder with an average particle size of about 1 μm or less, and the zirconia-based ceramic powder as a fine powder with an average particle size of about 1 μm or less, and stabilized or partially stabilized zirconia is preferred. The dispersion medium for preparing the slurry may be water or an aqueous solution of about 3% by weight of polyvinyl alcohol, or an organic solvent such as acetone or xylene. However, in order to reduce the porosity in the composite material prepreg in subsequent steps and to further promote sintering between the fine particles used, it is desirable to use a solution in which a precursor polymer synthesized by the co-hydrolysis condensation of zirconia and a metal alkoxide such as yttria, which produces stabilized zirconia by firing, is dissolved in an organic solvent. The concentration of BaZrO3 or zirconia-based ceramic powder in the slurry is preferably 50% to 80% by weight, which allows for efficient impregnation into the fiber bundle without increasing the slurry viscosity too much. A concentration of less than 50% by weight is undesirable because it results in excessively high porosity of the matrix. When using a precursor solution, a precursor concentration of 40% to 70% by weight is preferable as it prevents the slurry viscosity from becoming too high. A concentration of 70% or more by weight is undesirable because the viscosity becomes too high and may even gel. A concentration of 40% or less by weight does not efficiently densify the matrix.

[0019] Next, the slurry prepared in the second step is applied to and impregnated into the carbon-coated zirconia continuous fiber bundle, two-dimensional fabric, or three-dimensional fabric in the first step (S108, third step). If the surface of the zirconia fibers exhibits water repellency to the slurry with water as the dispersion medium, the water repellency can be suppressed by first impregnating it with a hydrophilic and highly volatile solvent such as acetone or methanol and then drying it. This application and impregnation process can be efficiently carried out using known bagging or pressurizing methods. In other words, a bagging method can be used in which fiber bundles, two-dimensional fabrics, or three-dimensional fabrics coated with slurry are placed in a bag, and the solvent is removed by vacuuming, while more slurry is added and vacuuming is repeated. Alternatively, when using fiber bundles or two-dimensional fabrics, a drawing method can be used in which fiber bundles coated or impregnated with slurry are drawn into a tube of a predetermined shape and molded while removing the solvent under pressure, or a pressurizing method can be used in which two-dimensional fabrics are stacked in a predetermined number of layers, sandwiched between stainless steel sheets, and molded under pressure.

[0020] Next, the molded body impregnated with slurry in the third step is dried, and if the precursor solution is mixed in the impregnation solution, it may be heated in a steam atmosphere to gel and decompose the precursor and volatilize the resulting organic components (S110, fourth step). In the fourth step, which involves removing water or organic solvents from the dried prepreg and drying or gelling and drying, the process of further impregnating with the precursor solution after drying or drying in a steam atmosphere, and removing water or organic solvents and drying or gelling and drying may be repeated as needed. That is, by repeating this process, the number of times the precursor solution impregnation and firing process in the fifth step can be reduced. The number of times this additional impregnation is preferably 1 to 4 times, and even if it is repeated 5 or more times, the pores in the prepreg are drastically reduced because the precursor has not been ceramicized, and the effect of densifying the matrix cannot be obtained. The heat treatment temperature is preferably between 60°C and 150°C. The water vapor atmosphere is achieved by placing the prepreg on a water bath during heat treatment and heat treating for a predetermined time. The holding time, depending on the temperature, is usually between 1 hour and 10 hours.

[0021] Next, the prepreg obtained in the fourth step is subjected to primary firing in an inert gas atmosphere at 1000°C to 1500°C (S112, fifth step). Primary firing is a process in which the matrix is ​​sintered while leaving the carbon interface layer intact, and the atmosphere is preferably a nitrogen gas atmosphere, an argon gas atmosphere, or a vacuum. Argon gas is particularly suitable because there is no possibility of nitride formation. The resulting composite material is called a preform, and its porosity may be 50% or more. Therefore, in order to further reduce the porosity, the polymer impregnation firing process, in which the preform is further impregnated with a precursor solution, gelled, and dried three or more times, and then subjected to primary firing, is repeated two or more times to densify it. The precursor solution is preferable if the precursor concentration is between 40% and 70% by weight, as this prevents the slurry viscosity from becoming too high and allows for efficient impregnation. A concentration above 70% by weight is undesirable because the viscosity becomes too high and may even gel. A concentration below 40% by weight does not allow for efficient densification of the matrix.

[0022] Next, the composite material obtained in the fifth step is subjected to final firing in air or a non-oxidizing atmosphere, if necessary, with the temperature at which the composite material will be used as the maximum heating temperature (S114, sixth step). This step may be carried out in the environment in which the composite material will actually be used, and is a final firing step in which the composite material will be used as the maximum heating temperature, firing in air to burn off the carbon layer which is the interface layer, and allowing the gap between the resulting fiber surface and matrix to function as the interface layer. The maximum heating temperature is preferably between 1400°C and 1600°C. Temperatures exceeding 1600°C are undesirable because they degrade the properties of the composite material.

[0023] Figure 2 is a schematic diagram of an apparatus for performing the hexane bubble flow method to coat fibers with carbon. In the diagram, nitrogen gas or argon gas is supplied from the gas inlet 10 to the reaction chamber 24 and discharged from the gas exhaust port 28. Gas flow meters 12a and 12b measure the gas flow rate supplied from the gas inlet 10. Gas flow meter 12a measures the gas flow rate without organic solvents, and gas flow meter 12b measures the gas flow rate with organic solvents. Test tube 14 contains organic solvent 16 and also contains organic solvent gas in the gas that has passed through gas flow meter 12b. Hexane is used as the organic solvent, for example, but is not limited to this. The stopcock 18 is opened when supplying gas containing organic solvents to the reaction chamber 24, and closed when not supplying them.

[0024] The temperature controller 20 controls the internal temperature of the tubular heating furnace 22. The tubular heating furnace 22 heats and maintains the temperature of the reaction chamber 24 to the firing temperature of the fibers 26, which are selected from zirconia continuous fiber bundles, two-dimensional fabrics, or three-dimensional fabrics. The oxidation resistance and high-temperature strength of the ceramic matrix composite material created in this manner will be evaluated.

[0025] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. <Example 1> First, in the first step, a predetermined amount of ethyl 3-oxobutanoate was mixed with a predetermined amount of zirconium tetra-n-butoxide. After the exothermic reaction was completed, a predetermined amount of H2O was diluted with 2-propanol and mixed. After the exothermic reaction was complete, a 2-propanol solution of yttrium tri-n-butoxide or erbium acetylacetonate was added in a calculated amount so that the amount of Y2O3 or Er2O3 relative to ZrO2 was a predetermined molar percentage, and the mixture was stirred for 15 minutes. Then, predetermined amounts of aluminum ethyl acetacetate diisopropylate, tetraethoxysilane, and tetra-i-propoxytitanium, which are metal oxide raw material alkoxides that act as crystallization inhibitors, were added, and a predetermined amount of H2O was diluted with 2-propanol and mixed. After the exothermic reaction was complete, the reaction was carried out using a rotary evaporator, gradually heating from room temperature in a water bath to remove the solvent and low-boiling components such as 2-propanol, which are hydrolysis products. The mixture was then concentrated to 95°C to obtain yttria or ervia-stabilized zirconia fiber precursors.

[0026] In the next second step, polycarbosilane (PCS) was added as needed, and the precursor obtained in the first step was placed in a spinning cylinder as a xylene solution of a predetermined concentration. The spinning cylinder was pressurized with nitrogen gas to approximately 2.5 MPa or less at a temperature at which the precursor solution was extruded with appropriate viscosity, and the precursor was extruded from a nozzle with a diameter of 100 μm while being continuously wound at a speed of approximately 1800 m / min. In the third step, the obtained raw fibers were heated in saturated steam at a rate of 10°C / hour from 45 to 200°C and held for 1 hour to make them infusible. Infusibility was confirmed by the fact that they did not melt on a hot plate at 150°C.

[0027] In the following fourth step, the infusible fibers were heated to 1000°C at a heating rate of 100-200°C / hour in air, an inert atmosphere, or an inert gas containing water at saturated vapor pressure at room temperature, and held for 1 hour for low-temperature firing, i.e., primary firing. The inert gas containing water at saturated vapor pressure was prepared by bubbling Ar gas into water at room temperature and then introducing it into the firing furnace. Fibers fired in air were white, while fibers fired in an inert atmosphere or an inert gas containing water at saturated vapor pressure at room temperature were black, and carbon analysis revealed they contained less than 6% carbon. The fiber diameter was approximately 6-20 μm. Table 1 shows the composition of the synthesized fiber precursors, fiber manufacturing conditions, and fiber properties. The three-digit number following the hyphen in the precursor entry is the synthesis lot number. Although there are precursors with the same composition, the synthesis conditions differ as shown in Table 1, so a note is added to indicate that they are from different synthesis lots. The notation for synthesis lot numbers is the same in Tables 2 and 3.

[0028] [Table 1]

[0029] Using these fibers, a rod-shaped one-dimensional reinforced composite material with a diameter of approximately 2 mm and a length of approximately 10 mm was manufactured using the process shown in Figure 1. First, using the apparatus shown in Figure 2, each fiber bundle from Table 1 was heated to 1000°C at a rate of 200°C / hour while introducing Ar gas containing hexane vapor into the annular furnace cavity containing the fiber bundles using the hexane bubble flow method, and held for 0.5 hours to coat the fiber surface with carbon. Figure 3 shows an SEM image of the fiber cross-section indicating the thickness of the coating. Next, the impregnation slurry was prepared. First, a slurry was prepared by mixing BaZrO3 or 8 mol% Y2O3-stabilized ZrO2 (8YSZ) fine powder, with an average particle size of 1 μm or less, with a 3 wt% aqueous polyvinyl alcohol (PVA) solution to a concentration of 75 wt%. The BaZrO3 slurry was prepared using a 50 wt% xylene solution of the precursor Zr-Y(0.1)-077 shown in Table 1, which was used in the synthesis of the fibers, to achieve a concentration of 75 wt% BaZrO3 fine powder.

[0030] Next, the prepared slurry was applied to or impregnated into a predetermined amount of fiber bundles as shown in Table 1, and then drawn into an alumina tube with an inner diameter of 2 mm and a length of 100 mm while removing excess solvent and slurry. After molding, the bundles were dried at 85°C for 5 to 10 hours. Then, a 50 wt% xylene solution of the precursor Zr-Y(0.1)-077 was vacuum-impregnated, and the bundles were dried at 85°C for 0.5 hours to produce round bar prepregs. Next, these prepregs were heated in an Ar gas atmosphere at 100°C / hour to 1000°C and held for 1 hour for primary firing. After firing, they were removed from the alumina tubes to produce preforms.

[0031] Next, a 65 wt% xylene solution of the precursor Zr-Y(0.1)-077, a 5YSZ precursor polymer synthesized by molecular design to contain 5 mol% Y2O3, was prepared and vacuum-impregnated into the resulting preform. After drying at 85°C for 0.5 hours, the impregnated precursor was gelled in a saturated water vapor atmosphere at 85°C, and this process of drying at 85°C for 0.5 hours was repeated four times. Then, in an Ar atmosphere, it was heated to 1000°C at 200°C / hour and held for 1 hour for an additional primary calcination. The resulting preform was then subjected to the PIP (Polymer Impregnation and Pyrolysis) method again, in which the precursor was impregnated and calcined, to produce a minicomposite (1D-CMC), which is a one-dimensional reinforced CMC.

[0032] Table 2 shows the fiber volume content and room-temperature flexural strength of 1D-CMC produced under the above manufacturing conditions. ZB and YSZ in CMC(ZB) and CMC(YSZ) represent BaZrO3 and 8 mol% Y2O3-stabilized ZrO2(8YSZ) used in the impregnation slurry. A maximum room-temperature flexural strength of 199 MPa was obtained. Figure 4 shows the stress-strain curve of the flexural test of CMC(ZB)-5. From this stress-strain curve, it was found that the produced 1D-CMC did not exhibit brittle fracture. Furthermore, referring to Figure 5, fiber pull-out was observed at the fracture surface, confirming that the interfacial layer was functioning adequately. [Table 2]

[0033] Table 3 shows the results of tensile tests of 1D-CMC at room temperature. CMC(ZB)-31, which had the lowest porosity, achieved a tensile strength of 175.3 MPa. In all cases, fiber pullout was observed in the forced fracture surface, confirming the function of the interfacial layer. [Table 3]

[0034] <Example 2> Similar to Example 1, 1D-CMC fabricated using fibers produced from the Zr-Y(0.1)-077+PCS(0.05) precursor was subjected to high-temperature treatment (equivalent to secondary firing) followed by a bending test at room temperature. The high-temperature treatment involved raising the temperature to 1500°C at a rate of 300°C / hour in a predetermined atmosphere and holding it for 1 hour. Table 4 shows the bending test results at room temperature for the treated 1D-CMC. CMC(ZB)-32 showed a bending strength of 252 MPa, confirming the strength improvement effect due to the reduction in porosity and densification caused by sintering of the matrix during secondary firing. Figure 6 shows an SEM image of the forced fracture surface of CMC(ZB)-15. From this figure, it was found that the carbon interface layer was burned off during atmospheric firing, forming a gap between the fiber and the matrix, and this gap acted as an interface layer, causing fiber pullout.

[0035] [Table 4]

[0036] <Example 3> Using fibers obtained by secondary calcination of Zr-Y(0.1)-077+PCS(0.05) precursor at 1300°C in air, a fiber bundle consisting of approximately 250 filaments was first carbon-coated in the same manner as in Example 1. This was then woven into a plain weave fabric, and a two-dimensional reinforced carbon polymer (2D-CMC) was fabricated using a process almost identical to that of Example 1. First, a slurry for impregnation was prepared. For the slurry, BaZrO3 or 8 mol% Y2O3-stabilized ZrO2 (8YSZ) was used as the fine powder. The BaZrO3 slurry was prepared using a 50 wt% xylene solution of the precursor Zr-Y(0.1)-077.

[0037] Next, the woven fabric was cut to dimensions of approximately 65 mm x 65 mm, the prepared slurry was applied or impregnated onto it, three layers were stacked, excess solvent was removed by bagging, and then the layer was pressed and fixed between stainless steel plates to form a prepreg. This prepreg was heated in a vacuum at 200°C / hour up to 1200°C and held at 1200°C for 1 hour to produce a preform. The obtained preform was impregnated with a precursor solution, dried, steam treated, and dried four times, and then subjected to primary firing (PIP treatment) at 1200°C. In this way, 2D-CMC was produced. A photograph of the appearance of the obtained 2D-CMC is shown in Figure 7. The thicknesses of 2D-CMC (YSZ) and 2D-CMC (ZB) were 2.0 mm and 2.8 mm, respectively. For these two types of 2D-CMC, heat resistance was evaluated by erosion testing using an erosion testing machine manufactured by Ishikawajima-Harima Heavy Industries Co., Ltd., with DC arc heating (20kW), a nozzle diameter of 75mm, and a test temperature of 1800℃ for 180 seconds.

[0038] Table 5 shows the characteristics of each CMC and the erosion test results. In all cases, there was almost no deformation and the mass change was very small, indicating excellent heat resistance. The thickness change was particularly small in 2D-CMC (YSZ), and despite the very high test temperature of 1800°C, the wear rate was 9.7 × 10⁻⁵ mm / sec, demonstrating high erosion characteristics. [Table 5] [Industrial applicability]

[0039] According to the method for producing ceramic matrix composites of the present invention, zirconia continuous fiber reinforced / zirconia-based ceramic matrix composites can be manufactured, and these oxide-based composite materials are suitable as gas turbine materials that can withstand combustion temperatures higher than those of conventional SiC / SiC composite materials. [Explanation of symbols]

[0040] 10 Gas supply port 12a, 12b Gas flow meter 14 test tubes 16. Organic solvent (hexane) 18 Cock 20 Temperature Controllers 22 Tubular heating furnace 24 Reaction Chamber 26 Fibers 28 Gas exhaust port

Claims

1. A first step to provide a two-dimensional or three-dimensional fabric made by coating zirconia continuous fibers with carbon, Fine granules of BaZrO ３ The second step involves preparing a slurry by mixing powder or zirconia-based ceramic powder with water or a precursor solution obtained by dissolving a zirconia-based ceramic precursor in an organic solvent in a predetermined ratio. A third step involves applying or impregnating the aforementioned slurry onto the aforementioned fabric to produce a prepreg, A fourth step involves drying or gelling and then drying the prepreg, A fifth step involves preparing a preform by firing it from room temperature in a non-oxidizing atmosphere at a predetermined heating rate to a predetermined temperature, then impregnating it with the precursor solution after firing, gelling it, and repeating the firing process to densify it. A method for producing an oxide-based ceramic matrix composite material using zirconia continuous fibers as reinforcing fibers.

2. A method for producing a ceramic matrix composite material according to claim 1, wherein in the fourth step, the slurry or the precursor solution is further added to the prepreg, and at least one of water or an organic solvent is removed, and then the material is dried or gelled and then dried.

3. A method for producing a ceramic matrix composite material according to claim 1, further comprising a sixth step of performing a final firing in air or a non-oxidizing atmosphere, with the temperature at which the composite material is used as the maximum heating temperature, following the fifth step.

4. The method for producing a ceramic matrix composite material according to Claim 1, characterized in that the average particle size of the BaZrO3 powder or the zirconia-based ceramic powder is 1 μm or less.

5. In the third step, The aforementioned prepreg is A prepreg (two-dimensional reinforced composite material) in which the fiber axes of the fabric are arranged in a two-dimensional direction, or This is a prepreg (three-dimensional reinforced composite material) in which the fiber axes of the fabric are arranged in a three-dimensional direction. A method for producing a ceramic matrix composite material according to feature 1.

6. The method for producing a ceramic matrix composite material according to claim 1, characterized in that the fifth step involves densifying a preform obtained by firing the prepreg obtained in the fourth step from room temperature to a predetermined temperature at a predetermined heating rate, by further impregnating the preform with a precursor solution, gelling it, and drying it three or more times, and then firing it two or more times in a polymer impregnation firing process.

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