JP3557939B2 - Matrix for high performance ceramic matrix composites - Google Patents

Description

【００４７】
【表２】

【００４８】
【表３】

【００４９】
【発明の効果】
本発明によれば、高温における耐熱性、耐酸化性及び機械的特性に優れた高強度複合材料用マトリックスが提供される。
本発明のマトリックスを用いて製造されたセラミックス基複合材料は、特に航空・宇宙分野における各種成形物等の材料として有用である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a matrix for a ceramic-based composite material using inorganic fibers as a reinforcing material.
[0002]
Problems to be solved by the prior art and the invention
Conventionally, various materials having excellent heat resistance and mechanical properties have been developed as materials used in the space and aviation fields, and ceramic-based composite materials and the like have been proposed as typical ones.
[0003]
As such a ceramic-based composite material, silicon carbide-based fibers are used as the reinforcing inorganic fibers and silicon carbide-based ceramics are used as the matrix because of its excellent heat resistance and oxidation resistance at high temperatures. In general, in the case of a large member, a composite material is obtained by forming a silicon carbide-based matrix on a silicon carbide-based fiber woven fabric by a CVI method (chemical vapor impregnation method) or a PIP method (polymer impregnation firing method).
[0004]
However, in this method, pores and microcracks tend to remain in the silicon carbide matrix. As a result, stress concentration occurs around the pores and microcracks, and the stress is not sufficiently transmitted from the matrix to the above fibers, and the strength of the composite material is reduced. There is a problem that the fibers enter through cracks, oxidize the fibers, and reduce the strength of the composite material.
[0005]
Accordingly, an object of the present invention is to provide a matrix for a high-strength composite material having excellent heat resistance, oxidation resistance and mechanical properties.
[0006]
[Means for Solving the Problems]
As a result of various studies, the present inventors have found that the above object can be achieved by using a matrix in which an oxide phase is dispersed in a silicon carbide-based ceramic.
[0007]
The present invention has been made based on the above-mentioned findings, and a matrix in a ceramic-based composite material using an inorganic fiber as a reinforcing material is 40 to 95% by weight of an amorphous silicon carbide-based ceramic and the silicon carbide-based ceramic. consists of a dispersed 5 to 60 weight percent on the oxide phase _{in, ZrSiO 4, BaO-MgO-} Al 2 O 3 -SiO 2 with the oxide phase has a network structure in the matrix An object of the present invention is to provide a matrix for a high-performance ceramic-based composite material, wherein the matrix is selected from the group consisting of a system glass ceramic and a SrO—Al ₂ O ₃ —SiO ₂ system glass ceramic.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the matrix for a high-performance ceramic-based composite material of the present invention will be described in detail. The matrix for a high-performance ceramic-based composite material of the present invention is composed of a silicon carbide-based ceramic and an oxide phase dispersed in the silicon carbide-based ceramic. That is, the matrix is a composite matrix of a silicon carbide-based ceramic and an oxide phase.
[0009]
Is the above oxide phase, can be mentioned oxides of crystalline and glass ceramics (crystallized glass) or the like.
[0010]
Specific examples of the oxides of the above crystalline, ZrSiO ₄ is exemplified et been, is preferably a thermal expansion coefficient at 1 000 ° C. is 8 × 10 ⁶ or less.
[0011]
Specific examples of the glass _{ceramic, SrO-Al 2 O 3 -SiO} 2 based glass ceramics and _{BaO-MgO-Al 2 O 3} -SiO 2 based glass ceramics.
[0012]
The oxide phase forms a continuous tissue Te matrix odor of the present invention (network structure). One kind of the substance constituting the oxide phase may be used, or plural kinds of substances may be used in combination.
[0013]
The method for forming the oxide phase is not particularly limited, but the following methods (a) to (c) are preferably used from the viewpoint of ease of formation.
[0014]
Method (a): a method using a powder of the substance forming the oxide phase.
[0015]
Method (b): a solution of a substance (that is, a precursor) that forms the oxide phase after mineralization, for example, a solution in which an alkoxide as a precursor is dissolved in a solvent such as an alcohol (sol-gel method), or a raw material A solution obtained by dissolving a salt as a precursor in a solvent such as water is impregnated into silicon carbide ceramics, and then heat-treated in an atmosphere containing NO ₂ gas and / or O ₂ gas and / or H ₂ O gas. how to.
[0016]
Method (c): Gas phase method such as CVD method, CVI method or PVD method. When using the CVD method or the CVI method, at least one gas or vapor of a halide, hydride, or organometallic compound of a metal constituting the oxide phase, and a NO ₂ gas and / or an O ₂ gas and / or A mixture with H ₂ O gas can be used as a source gas for a known CVD method or CVI method. When the PVD method is used, a compound or a mixture adjusted to have the same composition as the target oxide phase or a composition very similar thereto is used as a target, or a plurality of the compounds or the mixture are used. After performing PVD treatment so as to have the same composition as the target oxide phase by alternately using targets, for example, heat treatment may be performed if necessary to form an oxide phase.
[0017]
The abundance of the oxide phase in the matrix of the present invention is 5 to 60% by weight based on the entire matrix in view of the characteristics of the ceramic-based composite material .
[0018]
As the silicon carbide ceramics, ceramics having the following structure (1) or ceramics having the following structure (2) are preferably used from the viewpoint of properties such as strength, elastic modulus, heat resistance, oxidation resistance, and creep resistance. Can be
[0019]
Structure (1);
Real qualitatively Si, and Ti and / or Zr, and C, and a non-amorphous consisting of O; and flat elemental composition of the average is, Si is 30 to 80 wt%, C is from 15 to 69 wt% , O is 0.005 to 20% by weight.
[0020]
Structure (2);
Real qualitatively be Si, C and O and of amorphous; and elemental composition of the average is, Si is 30 to 80 wt%, C is 10 to 65 wt%, O is 0.005 to 25 weight Structure that is%.
[0021]
To elaborate on the structure (1) and (2), S i, the strength that the elemental composition of the average of C and O are as described above for the structure (1), elastic modulus, heat resistance, oxidation resistance It is preferable in view of characteristics such as creep resistance. More preferred ranges are 40 to 70% by weight of Si, 20 to 40% by weight of C, and 0.005 to 18% by weight of O.
[0022]
S i, the strength that the elemental composition of the average of C and O are as described above, the elastic modulus of the structure (2), heat resistance, oxidation resistance, from the viewpoint of properties such as creep resistance. More preferred ranges are 40 to 70% by weight of Si, 20 to 40% by weight of C, and 0.005 to 20% by weight of O.
[0023]
The method for forming the silicon carbide-based ceramic is not particularly limited, but the following methods (d) to (f) are preferably used from the viewpoint of ease of formation.
[0024]
Method (d): a method in which a raw material powder of a silicon carbide-based ceramic is blended and subjected to a heat treatment or a high-temperature pressure treatment.
[0025]
Method (e): Precursor polymer of silicon carbide-based ceramics that becomes silicon carbide-based ceramics after mineralization, such as polycarbosilane, polyzirconocarbosilane, polytitanocarbonosilane, perhydropolysilazane, polysilastyrene, and polycarbo Using a solution of silazane, polysilazane, or the like in an organic solvent that is a good solvent for the precursor polymer, such as toluene, xylene, or tetrahydrofuran, impregnate the inorganic fiber preform into the solution, and remove the solvent from the impregnated material. A method of forming a silicon carbide-based ceramic by performing a heat treatment after removing the silicon carbide. In this method, in order to obtain a silicon carbide-based ceramic having no internal voids, it is preferable to repeat a series of operations of impregnation of the precursor polymer, removal of the solvent, and heat treatment a plurality of times. In this method, the mineralization and densification or sintering of the precursor polymer proceed simultaneously.
[0026]
Method (f): A method based on a gas phase method such as a CVD method, a CVI method or a PVD method. When using the CVD method or CVI method, a halide of the metal constituting the silicon carbide-based ceramics, hydrides, and at least one kind of gas or vapor of the organometallic _{compound, C n H 2n + 2 (} n = 1 or more) Gas And / or a mixture with H ₂ gas can be used as a raw material gas for a known CVD method or CVI method. When using the PVD method, a compound or mixture adjusted to have the same composition as or very close to the composition of the target silicon carbide ceramic is used as a target, or a plurality of the compound or the mixture is used. After performing PVD treatment so as to have the same composition as the target silicon carbide-based ceramic by alternately using the respective targets, heat treatment is performed if necessary to form the silicon carbide-based ceramic.
[0027]
The heat treatment temperature in each of the above methods (d) to (f) is usually 800 ° C to 2000 ° C. The heat treatment is performed in an inert atmosphere such as N ₂ gas or Ar gas, in a vacuum, or in a reducing atmosphere such as H ₂ gas or CO gas.
[0028]
The abundance of the silicon carbide-based ceramic in the matrix of the present invention is particularly set at 40 to 95% by weight based on the entire matrix in view of the characteristics of the ceramic-based composite material .
[0029]
The ceramic-based composite material obtained by using the matrix of the present invention has excellent mechanical properties and fatigue properties at high temperatures. Although the reason is not clear, i) the stress concentration in the matrix is alleviated by the oxide phase, and the stress is effectively transmitted to the fiber, so that the strength of the composite material is improved. It is considered that the cracks are inhibited by the phase and the durability of the composite material is improved by the self-sealing effect of the microcracks in the matrix at a high temperature.
[0030]
The inorganic fibers used as the reinforcing material when the ceramic-based composite material is formed using the matrix of the present invention are not particularly limited, and include, for example, silicon carbide fibers, silicon nitride fibers, alumina fibers, and carbon fibers. Is preferable, and a silicon carbide fiber is particularly preferable.
[0031]
Examples of the silicon carbide-based fiber include inorganic fibers made of Si-Ti or Zr-CO or commercially available as "Tyranno fiber" (registered trademark) from Ube Industries, Ltd. or Si-Al-CO. Made of polycrystalline inorganic fiber or Si-CO which is commercially available from Nippon Carbon Co., Ltd. as "Nicalon" (registered trademark), "Hinicalon" (registered trademark) or "Hinicalon Type S" Fibers and the like can be mentioned.
[0032]
The amount of the inorganic fibers present in the ceramic-based composite material obtained by using the matrix of the present invention is preferably 5 to 85 vol% with respect to the entire ceramic-based composite material.
[0033]
The ceramic-based composite material includes a matrix obtained using the above-described silicon carbide-based ceramic forming methods (d) to (f) and the above-described oxide phase forming methods (a) to (c), It can be easily produced by using the above-mentioned inorganic fiber by the following method (g) or (h).
[0034]
Method (g): The above-mentioned inorganic fibers are mixed with the above-mentioned matrix comprising the oxide phase powder obtained by the above method (a) and the silicon carbide-based ceramic powder obtained by the above method (d), and subjected to heat treatment or high-temperature press treatment. Method. In this method, when the inorganic fiber is a short fiber, the mixture is a mixture of the short fiber inorganic fiber and the raw material powder of the matrix. When the inorganic fiber is a long fiber, a woven fabric, a nonwoven fabric, or a sheet-like material, the fiber material layer and the matrix material powder are alternately laminated, or the matrix material powder adheres to the fiber surface. The obtained long fiber bundle is formed into a laminate of a woven fabric, a nonwoven fabric or a sheet-like processed product. Then, after the mixture or the laminate is formed into a desired shape, or simultaneously with the formation, heat treatment is performed to densify or sinter the raw material powder of the matrix, whereby a ceramic-based composite material can be obtained.
[0035]
Method (H): The inside of an aggregate such as a woven fabric, a sheet or a nonwoven fabric of the above-mentioned inorganic fibers, or a short-cut product, and the oxide phase obtained by the above-mentioned methods (A) to (C) and the above-mentioned method (E) or (F) And forming a silicon carbide-based ceramic by the method described above. In this method, the formation of the oxide phase and the formation of the silicon carbide-based ceramic may be alternately repeated in order to change the degree of dispersion of the oxide phase and the ratio of the oxide phase. Further, the formation of the oxide phase and the silicon carbide-based ceramic can be performed simultaneously. For example, a solution obtained by dispersing the particles of the oxide phase according to the method (a) in the silicon carbide-based ceramic precursor polymerization solution according to the method (e) may be impregnated into the aggregate of the inorganic fibers to be mineralized. it can.
[0036]
The ceramic-based composite material obtained by using the matrix of the present invention has excellent mechanical properties and fatigue properties at high temperatures. Therefore, the ceramic-based composite material is particularly useful as a material for various molded articles in the aerospace field under extremely severe use environments.
[0037]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, "parts" and "%" indicate "parts by weight" and "% by weight", respectively, unless otherwise specified.
[0038]
Production Example 1 (Production of silicon carbide-based ceramic raw material)
2.5 liters of anhydrous xylene and 400 g of sodium were charged into a 5 liter three-necked flask, heated to the boiling point of xylene under a stream of N ₂ gas, and then 1 liter of dimethyldichlorosilane was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was heated and refluxed for 10 hours to produce a precipitate. This precipitate was filtered, and the precipitate was washed with methanol and then with water to obtain 410 g of white powdery polydimethylsilane.
Separately, 750 g of diphenyldichlorosilane and 124 g of boric acid are heated in n-butyl ether at 100 to 120 ° C. under a stream of N ₂ gas, and the resulting white resinous material is further heat-treated at 400 ° C. in vacuum for 1 hour. As a result, 515 g of polyborodiphenylsiloxane was obtained. 8.2 g of this polyborodiphenylsiloxane and 250 g of the polydimethylsilane obtained above were mixed, heated to 350 ° C. in a quartz tube equipped with a reflux tube under a stream of N ₂ gas, and stirred at 350 ° C. While holding for 6 hours, 138 g of polycarbosilane partially containing a siloxane bond was obtained. After dissolving 40 g of this polycarbosilane and 7.3 g of titanium tetrabutoxide in 0.3 liter of xylene, the mixture was refluxed with stirring at 120 ° C. for 30 minutes in an N ₂ gas stream. Thereafter, xylene was evaporated, further heated at 300 ° C. for 1 hour under a stream of N ₂ gas, and allowed to cool to obtain a solid polytitanocarbosilane at room temperature.
[0039]
Production Example 2 (production of oxide phase raw material)
BaO, MgO, Al ₂ O ₃ , and SiO ₂ powder were mixed at a mixing ratio of BaO: MgO: Al ₂ O ₃ : SiO ₂ = 14: 8: 28: 50 to obtain a total of 1000 g to obtain a mixed powder for glass. This mixed powder was filled in a platinum crucible, heated and melted at 1600 ° C. or higher, and then rapidly cooled. The obtained glass was pulverized so as to have an average particle diameter of 10 μm or less to obtain a glass ceramic powder. This powder is hereinafter referred to as BMAS glass ceramic powder.
[0040]
Production Example 3 (production of oxide phase raw material)
Diethoxystrontium (Sr (OC ₂ H ₅ ) ₂ ), aluminum isopropoxide (Al (OCH (CH ₃ ) ₂ ) ₃ ), tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) 17.7%, 100 parts of a mixture of 40.7% and 41.6% was heated to reflux in 100 parts of isopropyl alcohol and dissolved. This solution is hereinafter referred to as a SAS-based sol-gel solution.
[0041]
Example 1
The mixed solution of 100 parts of polytitanocarbosilane and 100 parts of xylene obtained in Production Example 1 was mixed with the BMAS glass ceramic powder obtained in Production Example 2 in a ratio of the glass ceramic powder to the total weight of the matrix after firing. A slurry was prepared by adding the slurry to 10%. A commercially available “Tyranno Fiber TM-S6” (trade name, manufactured by Ube Industries, Ltd.) is opened, immersed in the slurry, deaerated under a reduced pressure of 500 Torr, and then degassed under a 4 atm argon gas atmosphere. To impregnate the fiber bundle. The impregnated fiber bundle was heated to 100 ° C. under a stream of argon gas to remove xylene by evaporation. Next, in an electric furnace, the temperature was raised to 1300 ° C. at a rate of 50 ° C./hour under a nitrogen gas flow, and the temperature was maintained at 1300 ° C. for 1 hour, and then lowered to 1000 ° C. at a rate of 100 ° C./hour. Then, it was allowed to cool to room temperature, and the impregnated material was fired. By repeating this impregnation and firing five times, a composite material using the matrix of the present invention was obtained. Table 1 shows the tensile strength of the obtained composite material. The tensile strength is based on the “Test method for tensile stress-strain behavior of room temperature and high temperature of long fiber reinforced ceramic matrix composite material (PEC-TS CMC 01-1997)” of the “Petroleum Industry Activation Center” Material Testing Standard. Measured.
[0042]
Examples 2 to 4 and Comparative Examples 1 and 1a
A composite material was obtained in the same manner as in Example 1, except that the ratio of the BMAS glass ceramic powder in Example 1 was changed to the ratio shown in Table 1. Table 1 shows the tensile strength of the obtained composite material.
[0043]
Example 5
A commercially available "Tyranno fiber ZMI-S5" (trade name, manufactured by Ube Industries, Ltd.) was used instead of the "Tyranno fiber TM-S6" used in Example 1, and a commercially available ZrSiO2 was used instead of the BMAS glass ceramic powder. _A composite material was obtained in the same manner as in Example 1 except that ₄ powders (manufactured by Wako Pure Chemical Industries, Ltd.) were used. Table 2 shows the tensile strength of the obtained composite material.
[0044]
Examples 6 to 8 and Comparative Examples 2 and 2a
A composite material was obtained in the same manner as in Example 5 , except that the ratio of the ZrSiO ₄ powder in Example 5 was changed to the ratio shown in Table 2. Table 2 shows the tensile strength of the obtained composite material.
[0045]
Example 9
The impregnation material was fired once in the same manner as in Example 5 . By this impregnation and firing, a silicon carbide matrix portion is formed. Next, the fiber bundle partially formed with the silicon carbide-based matrix was immersed in the SAS-based sol-gel solution obtained in Production Example 3, deaerated under a reduced pressure of 500 Torr, and then subjected to an argon gas atmosphere of 4 atm. The fiber bundle was impregnated inside. The impregnated fiber bundle was heated to 80 ° C. in a stream of air to remove isopropyl alcohol by evaporation. Next, in an electric furnace, the temperature was raised to 800 ° C. at a temperature rising rate of 50 ° C./hour under an air flow, and the temperature was maintained at 800 ° C. for 1 hour. Was. The impregnation and mineralization, formation of oxide phase matrix portion consisting of _{SrO-Al 2} O 3 -SiO 2 based glass ceramics is carried out. By repeating formation of the silicon carbide matrix part and formation of the oxide phase matrix part three times, a composite material using the matrix of the present invention was obtained. The ratio of the oxide phase matrix portion to the weight of the entire matrix was 35%. Table 3 shows the tensile strength of the obtained composite material.
[0046]
[Table 1]

[0047]
[Table 2]

[0048]
[Table 3]

[0049]
【The invention's effect】
According to the present invention, a matrix for a high-strength composite material having excellent heat resistance, oxidation resistance and mechanical properties at high temperatures is provided.
The ceramic-based composite material manufactured using the matrix of the present invention is particularly useful as a material for various molded products in the aerospace field.

Claims (3)

The matrix in the ceramic-based composite material using inorganic fibers as a reinforcing material comprises 40 to 95% by weight of an amorphous silicon carbide-based ceramic and 5 to 60% by weight of an oxide phase dispersed in the silicon carbide-based ceramic. consists, oxide _{phase, ZrSiO 4, BaO-MgO-} Al 2 O 3 -SiO 2 based glass ceramics and SrO-Al ₂ O ₃ -SiO ₂ based glass with has a network structure in the matrix A matrix for a high-performance ceramic-based composite material, wherein the matrix is selected from the group consisting of ceramics. 2. The matrix for a high-performance ceramic-based composite material according to claim 1, wherein the silicon carbide-based ceramic constituting the matrix has the following structure (1).
Structure (1);
Real qualitatively Si, and Ti and / or Zr, and C, and a non-amorphous consisting of O; and flat elemental composition of the average is, Si is 30 to 80 wt%, C is from 15 to 69 wt% , O is 0.005 to 20% by weight. The matrix for a high-performance ceramic-based composite material according to claim 1, wherein the silicon carbide-based ceramic constituting the matrix has the following structure (2).
Structure (2);
Real qualitatively be Si, C and O and of amorphous; and elemental composition of the average is, Si is 30 to 80 wt%, C is 10 to 65 wt%, O is 0.005 to 25 weight Structure that is%.