JP4542792B2 - Oxidation resistant materials and non-oxide based composite materials - Google Patents

Description

  The present invention relates to an oxidation resistant material and a non-oxide composite material having excellent oxidation resistance.

Since carbon-based materials such as carbon and silicon carbide have excellent heat resistance, they have been used as a base material for heat-resistant members. On the other hand, since a carbonaceous material is easily oxidized, it is necessary to prevent oxidation. For this reason, an oxide layer is imparted to the surface of the carbon-based material to prevent corrosion species such as oxygen and water vapor from diffusing inward in the carbon-based material. As such an antioxidant technique, for example, there is a technique in which a silicon carbide layer is formed on the surface of a carbon material via a silicon layer, and silicon dioxide and mullite are coated thereon (Non-patent Document 1). Further, there is a carbon material whose surface is coated with silicon carbide, YSi _x , Y ₂ SiO ₅ in this order (Non-patent Document 2). All of these have a multilayer coating structure, but the oxide layer is not dense, so that sufficient oxidation resistance cannot be obtained.

  In order to obtain a dense oxide layer, it is effective to melt and coat the glass, but the carbon-based material is inferior in wettability to the molten glass. For this reason, there is a method in which a Si or SiC layer is formed in advance on the surface of a carbon-based material to improve wettability, and then glass is melted and coated. There is also a method in which the surface of a carbon-based material is melted and coated with glass containing a ceramic filler such as SiC or MoSi (Patent Document 1). However, at temperatures exceeding 1500 ° C, which will be used in next-generation gas turbines, the glass remelts, resulting in sufficient oxidation resistance for the corrosive species to diffuse at high speed in the glass melt. Couldn't get. Furthermore, the Si-based compound used for imparting oxidation resistance has a high equilibrium vapor pressure of the gas generated by steam oxidation, and the volume of the coating layer is reduced by volatilization.

On the other hand, coating layers other than silicon compounds have been studied. For example, a method of coating Ta ₂ O ₅ on the surface of a silicon-based material is disclosed (Patent Document 2). In this method, since Ta ₂ O ₅ undergoes volumetric shrinkage when the phase transformation from the low temperature type (β) to the high temperature type (α), an oxide such as Al is added to suppress this phase transformation, Even at high temperatures, low temperature molds are present to ensure heat resistance. However, this method only uses the low temperature type of Ta ₂ O ₅ .

JP-A-10-167860 US Patent Application Publication No. 2002/0136835 Fritz et al., “Journal of European Ceramic Society” (UK), 1998, p.2351-2364 Masayuki Kondo and three others, Journal of the Japan Institute of Metals, 1999, 63, p.851-858

As described above, there has been no technique for imparting good corrosion resistance to a carbon-based material in a high temperature environment of 1100 ° C. or higher.
Therefore, an object of the present invention is to provide an oxidation resistant material having excellent oxidation resistance. Another object of the present invention is to provide a non-oxide composite material having excellent oxidation resistance.

The present inventors have found that oxidation resistance can be expressed by utilizing the conductivity (hole conductivity) and proton conductivity of the oxide-based proton conductive material, and the oxide-based proton conductive material. Good oxidation resistance for non-oxide materials by applying an oxidation-resistant layer comprising non-oxide materials such as carbon-based materials to the surface of an oxide-based material layer covering the surface of the material. The present invention has been completed.
That is, according to the present invention, the following means are provided.

The oxidation resistant material of the present invention is
It is specified by being a sintered body having an oxide-based proton conductive material phase. The oxide proton conductive material is preferably La _1-X Me _X (PO ₄ ) (where Me is a divalent metal atom, and 0 <X ≦ 0.1). The divalent metal atom may be one or more selected from the group consisting of Mg, Ca, Sr and Ba. These metal oxides are mainly composed of LaPO ₄ which is excellent in heat resistance and chemical stability and have proton conductivity. Therefore, these metal oxides are suitable for oxidation resistant materials, particularly for oxidation resistance in a high temperature and high humidity environment.

  The sintered body preferably includes an oxide-based proton conductive material phase and an oxide-based aprotic conductive material phase. That is, a structure in which an oxide-based proton conductive material phase and an oxide-based aprotic conductive material phase are combined can be employed. In such a composite sintered body, the oxide-based aprotic conductive material phase functions as a proton blocking layer because it does not retain protons and does not diffuse. The composite form of the sintered body is a form having a laminated structure of an oxide-based proton conductive material phase and an oxide-based aprotic conductive material phase or an oxide-based proton conductive material phase and an oxide-based aprotic conductivity. It can take the form of having a dispersed structure with the material. Further, these two composite forms can be used in combination.

The oxide-based aprotic conductive materials in these oxidation resistant materials are Ta ₂ O ₅ , Al ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , SiO ₂ , TiO ₂ , Al ₆ Si ₂ O ₁₃ (mullite), One or two or more selected from the group consisting of Y ₂ SiO ₅ , LaPO ₄ , LaAlO ₃ , and ScTaO ₄ can be used, preferably Ta ₂ O ₅ , Al ₂ O ₃ , Y ₂ O _3. Y ₂ SiO ₅ or ScTaO ₄ .

  Such an oxidation resistant material exhibits good oxidation resistance even under a high temperature and / or high humidity environment, but particularly exhibits good oxidation resistance under a high temperature and / or high humidity environment of 1100 ° C. or higher. be able to.

The composite material of the present invention is
A non-oxide base material;
An oxidation resistant layer made of the oxidation resistant material located on the surface side of the substrate;
Is specified.

The composite material of the present invention is
A non-oxide base material;
An oxidation resistant layer located on the surface side of the substrate;
With
The oxidation resistant layer is
A first oxidation-resistant layer comprising an oxide-based proton conductive material phase; a second oxidation-resistant layer comprising the oxide-based proton conductive material phase and an oxide-based aprotic conductive material phase; and the oxidation A third oxidation-resistant layer having a physical aprotic conductive material phase can also be contained.

In this composite material, the second oxidation-resistant layer may have a gradient composition of the oxide-based proton conductive material phase and the oxide-based aprotic conductive material phase. The graded composition may be continuous or discontinuous. In the case of discontinuous, it can be constituted by laminating layers having different blending ratios of the oxide-based proton conductive material and the oxide-based aprotic conductive material. The oxide-based proton conductive material can be La _1-X Me _X (PO ₄ ) (where Me is a divalent metal atom, and 0 <X ≦ 0.1). Further, the divalent metal atom may be one or more selected from the group consisting of Mg, Ca, Sr and Ba. Furthermore, the non-oxide base material may be made of either or both of a carbon-based material and a metal. Furthermore, such a composite material can be a structural member used in a high temperature environment of 1100 ° C. or higher.

Hereinafter, embodiments for carrying out the present invention will be described in detail.
The oxidation-resistant material and the non-oxide composite material of the present invention can be characterized in that they each include an oxide-based proton conductive material (hereinafter simply referred to as proton conductive material) phase. By providing the proton conductive material phase, good oxidation resistance can be exhibited, and good oxidation resistance can be imparted to the non-oxide base material.

Although not binding the present invention, the oxidation resistance effect due to the presence of the proton conductive material phase is:
(1) Oxygen molecules that are corrosive species, water (including water vapor, hereinafter the same), anionization (generation of oxygen ions and hydroxyl ions) of the molecules is suppressed to suppress anionization adsorption,
(2) suppressing diffusion of oxygen ions that have already been generated in the direction of the non-oxide base material; and (3) generating protons at the interface in contact with a hydrogen supply source such as water molecules, Further suppressing oxidation by inward diffusion and increasing proton concentration,
It is thought that any one of these or the combination of 2 or more types contributes.

  The oxidation-resistant material of the present invention exhibits an excellent oxidation resistance by including an oxide-based proton conductive material phase, and the non-oxide-based composite material having the oxidation-resistant material on the surface layer side has a good acid resistance. It is possible to demonstrate the chemical properties. Hereinafter, an oxidation resistant material will be described, and then a non-oxide composite material including the oxidation resistant material on the surface layer side will be described.

(Oxidation resistant material)
(Proton conductive material phase)
The oxidation resistant material of the present invention comprises a proton conductive material phase. As the proton conductive material, any oxide-based material exhibiting proton conductivity under the usage environment of the material is sufficient. Examples of the oxide materials include metal oxides, metal double oxides, and metal salts containing various oxygen ions. When the use environment of the oxidation resistant material is 1100 ° C. or higher, the proton conductive material preferably exhibits proton conductivity in a predetermined temperature range at least at 1100 ° C. Note that an oxide exhibiting proton conductivity in a use environment is sufficient, and an oxide material exhibiting proton conductivity in a non-use environment or at room temperature is not excluded. The operating environment temperature can be 1300 ° C. or higher, preferably 1500 ° C. or higher.

  Proton conductivity is based on the fact that holes can be formed inside the crystal by having oxygen vacancies inside the crystal. As a case where there is a hole forming ability, for example, the oxide material has oxygen deficiency, and there is a case where holes are generated by contact with oxygen and an equilibrium reaction with oxygen. The oxygen vacancies in the oxide-based material are generated, for example, by substituting some metal atoms in the metal oxide with other metal atoms having a lower valence than the metal atom. An oxide-based material having oxygen vacancies exhibits hole conductivity (hole conductivity) and proton conductivity by the following mechanism according to the surrounding environment.

First, in a dry atmosphere containing oxygen, holes are formed in the crystal lattice by an equilibrium reaction between oxygen and the proton conductive material according to the following formula.
(Dry atmosphere) Vo ^·· + 1 / 2O ₂ ⇔Oo ^x + 2h ^·
(Where Vo ^·· is an oxygen deficiency (effective charge +2 oxygen vacancies) in the material, Oo ^x is an oxygen ion at a normal lattice position in the material ( ^x is an effective charge 0), h ^· Is a hole (effective charge + 1).)
As for the form of oxygen deficiency, for example, when the oxide is a phosphate, pyrophosphate ions (P ₂ O ₇ ²⁻ ), which are generated by orthophosphoric acid ions (PO ₄ ³⁻ ) sharing oxygen, Metaphosphate ions (PO ₃ ⁻ ) are considered to exist as oxygen vacancies. Thus, when oxygen vacancies are formed due to oxygen deficiency or the like, holes are generated in the crystal by contact with oxygen outside the system. The holes once generated are diffused into a region having fewer holes, for example, inward.

On the other hand, in a humid atmosphere, protons are taken into the material according to the following formula.
(Humid atmosphere)
H ₂ O + 2h ^· ⇔2H _i ^· + 1 / 2O ₂
Vo ^·· + H ₂ O⇔Oo ^x + 2H _i ^·
(However, _{H i} ^·: a interstitial protons.)
Holes in the material are consumed by an equilibrium reaction with water vapor, and at the same time, protons are taken into the material. The oxygen vacancies also take in oxygen into the normal lattice positions in the material and take in protons between the lattices by an equilibrium reaction with water vapor. Thus, when protons are taken from the external environment, the protons diffuse inward at a lower concentration.

  In the proton conductive material, in the environment where oxidation resistance is required, that is, in the environment where oxygen partial pressure or water vapor partial pressure is high, hole conductivity and proton conductivity are the main components. As described above, adsorption of anion species such as oxygen ions and hydroxyl ions and inward diffusion of oxygen ions are suppressed. In addition, the diffusion of protons can result in lowering the oxygen partial pressure in the material and impart oxidation resistance. In addition, when oxygen ions diffuse in the material, they are trapped by the generated holes, thereby providing oxidation resistance.

As the oxide-based proton conductive material, known materials can be used alone or in combination of two or more, but SrCeO ₃ system, CaZrO ₃ system, and La _1-X Me _X (PO ₄ ) (however, Me is a divalent metal atom, and 0 <X ≦ 0.1. Among these, it is preferable to use La _1-X Me _X (PO ₄ ), and in this case, Mg can be Mg, Ca, Sr, and Ba. Me is preferably Sr and Ba. As Me, any one of these or a combination of two or more types can be used. More preferred are Sr and Ba.

In La _1-X Me _X (PO ₄ ), x is not particularly limited within the above range, but may be in the solid solution range. For example, Sr can be in the range of about 0.07 or less, preferably about 0.05, and Ba can be in the range of about 0.01 or less, preferably about 0.01. It is.

(Structure of oxidation resistant material)
The oxidation resistant material may be composed of only the proton conductive material phase or may be combined with other materials. Even in the case of forming only from the proton conductive material phase, two or more types of proton conductive material phases can be combined. Compounding can be a dispersed structure in which two or more types of proton conductive materials are dispersed, or a laminated structure in which two or more types of proton conductive material layers are laminated.

  The oxidation-resistant material is composed of a proton conductive material phase and another material in combination with a dispersed structure of both phases, and the proton conductive material phase and other material phases are both layered. It can be a laminated structure or the like. In the case of a dispersed structure, the proton conductive material phase can be used as a matrix and another material phase can be used as a dispersed phase, or the other material phase can be used as a matrix and the proton conductive material phase can be used as a dispersed phase. These laminated structure and dispersed structure may have a gradient composition. When the proton conductive material phase is provided as a dispersed phase, the proton conductive material phase can form a discontinuous dispersed phase in the matrix, or the proton conductive material particles can be continuously formed by a percolation structure or other forms. A phase can also be formed. In the case of a laminated structure, the proton conductive material phase and other material phases can be alternately laminated, or two or more different or similar proton conductive material phases can be laminated in succession. These material phases can also be laminated.

  Various forms of the oxidation resistant material are illustrated in FIG. The oxidation-resistant material 2a in FIG. 1 (a) is a single-phase material form of the proton conductive material phase 4. The oxidation-resistant materials 2b and 2c in FIGS. The oxidation resistant materials 2d and 2e shown in FIGS. 1D and 1E are material forms having a dispersed structure of the proton conductive material phase 4 and the other material phase 6. . The oxidation resistant material 2d in FIG. 1 (d) is a material form of a dispersed structure in which the proton conductive material phase 4 constitutes a matrix and the other material phase 6 constitutes a dispersed phase. The chemical material 2e is a material form of a dispersed structure in which the other material phase 6 constitutes a matrix and the proton conductive material phase 4 constitutes a dispersed phase. The oxidation-resistant material can adopt a form in which two or more of these various material forms are combined by lamination or the like. Furthermore, other materials can be combined by lamination or the like.

  In any of these cases, by providing the proton conductive material phase 4, even if corrosive species (oxygen, water vapor) are present in the surroundings, the anionization adsorption can be suppressed, thereby suppressing the diffusion of oxygen ions. . In addition, even if oxygen ions diffuse in this material, these oxygen ions are trapped by the holes that are retained or generated in the proton conductive material phase 4, resulting in diffusion of oxygen ions in the oxidation resistant material. Can be suppressed. When the proton conductive material phase 4 exists as a matrix or continuous phase, in a wet atmosphere, protons diffuse inward due to proton conduction, and the oxygen partial pressure is lowered to reduce oxidation as a whole. Can be suppressed.

  When the proton conductive material phase 4 and the other material phase 6 are combined (including both the laminated structure and the dispersed structure), the proton conductive material phase 4 generates oxygen ions and hydroxyl ions. In addition, inward diffusion of oxygen ions is suppressed, and proton conductivity in the material is also suppressed to some extent. For example, when the non-oxide base material is coated with the oxidation-resistant material and the non-oxide base material and the proton are reactive, the suppression of proton diffusion This is useful in that the arrival rate of protons at the system substrate interface can be suppressed. In addition, the composite oxidation-resistant material can be blended so as to adjust the thermal expansion coefficient by using a material other than the proton conductive material.

As the other material phase 6 to be combined with the proton conductive material phase 4, it is preferable to use an oxide-based aprotic conductive material (hereinafter referred to as an aprotic conductive material). This is because the oxide-based material is excellent in chemical stability such as oxidation resistance and / or heat resistance. In addition, being an aprotic conductive material means that it is mainly composed of electron conductivity and / or oxygen ion conductivity when exhibiting conductivity. Since the non-proton conductive material blocks the invasion of protons, when the oxidation-resistant material constitutes a laminated structure, the non-proton conductive material phase 6 is closer to the external environment side than the proton conductive material phase 4, that is, the surface layer side. In the case of being provided in the proton conductive material, the proton is prevented from reaching the proton conductive material, and in the case of being provided inside the proton conductive material, the proton is blocked at the interface with the proton conductive material phase 4. The conductive material phase 4 acts to hold protons.
Further, when the oxidation resistant material constitutes a dispersed structure, when the proton conductive material phase 4 is a matrix and the non-proton conductive material phase 6 is a dispersed phase, it becomes a barrier for proton movement and suppresses its diffusion, When the proton conductive material is a dispersed phase and the aprotic conductive material is a matrix, it becomes a barrier to the movement of oxygen ions moving in the aprotic conductive material phase and suppresses its diffusion.

  Such an aprotic conductive material preferably has a melting point of 1500 ° C. or higher and has low or almost no reactivity with the proton conductive material. As such an oxide-based material, various known metal oxides (including double oxides and metal salts containing oxygen species) can be used. In use environment temperature, it may be ionic conductivity or electronic conductivity. In the case of electron conductivity, an n-type semiconductor is preferable. Further, it is sufficient that ion conductivity and the like are expressed at a high temperature. Therefore, even an oxide that does not exhibit ionic conductivity near room temperature can be used as long as it exhibits ionic conductivity at a high temperature. At the same time, an oxide material exhibiting ion conductivity or the like at room temperature or high temperature can be used. The use environment temperature is not particularly limited, but can be about 1100 ° C. or higher. Preferably it is 1300 degreeC or more, More preferably, it is 1500 degreeC or more. Moreover, it is preferable that the upper limit of use environment temperature is about 1800 degreeC or less. It is preferable to use a material mainly composed of ionic conductivity or electron conductivity at 1500 ° C. or higher and 1700 ° C. or lower.

Examples of the aprotic conductive material include Ta ₂ O ₅ , Al ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , SiO ₂ , TiO ₂ , Al ₆ Si ₂ O ₁₃ (mullite), LaPO ₄ , and LaAlO ₃ . Can be used. Ta ₂ O ₅ is preferable because TaC can be obtained when TaC is used as a part of the non-metal oxide material base material. Al ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , and LaPO ₄ are preferable because they are excellent in high-temperature stability (high melting point, low vapor pressure) in an oxidizing atmosphere. LaPO ₄ is composed of Al ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ (which may be used as a heat shielding layer on the surface side. The heat shielding layer will be described later), and a metal material-based substrate. It is also preferable in terms of low chemical reactivity. When using a material that causes phase transformation due to temperature such as Ta ₂ O ₅ and can cause a large volume change, the phase is maintained in a high temperature phase (α type) in advance, and a low temperature type (β type). It is preferable to suppress the phase transformation to. In the case of Ta ₂ O ₅ , phase transformation can be suppressed by adding scandium, chromium, iron, gallium, and tin oxides. These metal oxides can be used alone or in combination of two or more. Scandium oxide (Sc ₂ O ₃ ) is preferable as an additive because it is excellent in both oxidation resistance and reduction resistance at the use environment temperature.

Examples of the aprotic conductive material include Y ₂ SiO ₅ and ScTaO ₄ . Among these, ScTaO ₄ can be preferably used. This is because ScTaO ₄ is excellent in both oxidation resistance and reduction resistance at the use environment temperature, and also has excellent adhesion when TaC is used as a part of the non-oxide material base material as will be described later. .

  When this oxidation resistant material is a dispersed structure of a proton conductive material phase and another material phase, the mixing ratio of the proton conductive material phase in the dispersed structure depends on the purpose of adopting the dispersed structure, but the oxidation resistance From the viewpoint of securing the property, the content is preferably 5% by volume or more of the entire oxidation resistant material. This is because if it is less than 5% by volume, it is difficult to suppress the diffusion of oxygen ions because too few holes are generated. More preferably, it is 10 volume% or more, More preferably, it is 15 volume% or more.

  In addition, this oxidation-resistant material can contain an additive material for imparting a function such as strength or shape retention to the sintering aid or the present material as necessary. As the additive material, for example, reinforcing materials having various shapes such as a fiber shape and a chip shape can be added.

Such an oxidation resistant material can be obtained by using a proton conductive material or a combination of the proton conductive material and other materials to form a sintered body. These production methods are not particularly limited, and can be produced according to a known method for producing a ceramic sintered body. For example, oxide powder mixed pressure forming sintering method, coprecipitate sintering method, spray drying baking method, solution mixing sol-gel baking method, plasma spraying method such as plasma spraying method, physical vapor deposition (PVD), chemical vapor deposition The method (CVD) or the like can be used. Specifically, the method includes a step of mixing these raw materials and a step of firing the mixture. For example, co-precipitates are prepared by co-precipitation of raw materials such as nitrates and ammonium salts, which are calcined, and the mixed powder thus obtained is formed into a shape of a substrate or the like, and an oxygen-containing atmosphere such as in the atmosphere Can be fired. The firing temperature for obtaining the present oxidation resistant material is not particularly limited, but is preferably 1200 ° C. or higher in consideration of the sinterability of the proton conductive material and the application (oxidation resistance at 1100 ° C. or higher). More preferably, it is 1400 degreeC or more. For example, in the case of La _1-X Ba _X (PO ₄ ), the temperature is preferably 1400 ° C. or higher and 1600 ° C. or lower, and in the case of La _1-X Sr _X (PO ₄ ), it is 1200 ° C. or higher and 1400 ° C. or lower. preferable.

  The oxidation-resistant material can be formed into a molded body having a predetermined shape depending on the application, in addition to the plate-like body, the columnar body, and the tubular body. Furthermore, the oxidation resistant material is molded as an oxidation resistant film that covers the surface layer side of a non-oxide base material such as a metal or a non-metal oxide, and has another aspect of the present invention, the oxidation resistance. A non-oxide composite material having the same can be obtained.

(Non-oxide composite materials)
The non-oxide composite material in the present invention (hereinafter referred to as the present composite material) can be imparted with oxidation resistance to the substrate by being applied to the surface layer side of the non-oxide substrate. The oxidation resistant material preferably takes the form of a layer or film covering the substrate surface or the surface layer side of the substrate surface. Such a material form can be realized by a known ceramic forming method.

(Non-oxide base material)
As the material of the non-oxide base material in the composite material, metals and non-metal oxides can be used. These can be used alone or in combination. As the metal, stainless steel, Ni-base superalloy, Co-base superalloy, and MCrAlY (M is one or more selected from the group consisting of Ni, Co, and Fe) or one of these. Or it is preferable to set it as the alloy containing 2 or more types. Specifically, NiCoCrAlY, Inconel 738, HS-188, or the like can be used.

In addition, as the nonmetal oxide, a material other than the metal oxide such as a nonmetal, a metal nitride, a metal carbide, or a metal carbonitride can be used. A preferable base material includes a carbon-based material configured to contain carbon. Examples of the carbon-based material include carbon materials made of various forms of carbon such as carbon, isotropic graphite, and carbon fiber, and materials obtained by combining these carbon materials with other non-metal oxide materials. For example, a carbon material may be formed by laminating a metal carbide-based material containing a metal carbide such as tantalum carbide or silicon carbide to form a composite. Note that, as a material to be laminated, non-oxide materials such as metal nitride and metal boride can be used in addition to metal carbide. Specific examples include TaC, TiC, SiC, ZrC, HfC, Si ₃ N ₄ , TiN, TaN, ZrN, HfN, TaB ₂ , TiB ₂ , and ZrB ₂ . Of these, TaC, TiC, SiC, and ZrC are preferably used. More preferably, TaC or SiC is used. These carbon-based materials can also be used in combination with metals.

  Note that the thickness of the non-metal oxide material layer stacked on the carbon-based material is not particularly limited, but is preferably 0.1 μm or more and 50 μm or less. If the thickness is less than 0.1 μm, it is difficult to obtain a dense layer. As a result, carbon in the base material diffuses outward easily, reducing the oxidation-resistant layer on the surface side and generating a large amount of CO gas. Thus, the adhesion between the oxidation resistant material on the surface layer side and the non-metal oxide material layer is significantly reduced. When it exceeds 50 μm, it becomes difficult to alleviate the interfacial strain induced by the difference in thermal expansion coefficient between the base material and the oxidation-resistant material and the non-oxide material, resulting in a decrease in adhesion. More preferably, they are 1 micrometer or more and 10 micrometers or less.

  Moreover, the base material which comprises the dispersion structure | tissue of other nonmetallic oxide materials, such as a carbon material and a tantalum carbide and a silicon carbide, can also be used. For example, a substrate having a composite structure in which one of carbon and silicon carbide is a matrix and the other is a dispersed phase (fibrous or powdery) can be used. Typical examples include a base material in which carbon fibers are dispersed in a carbon matrix, a base material in which carbon fibers are dispersed in a SiC matrix, and a composite material having SiC fibers and a SiC matrix.

  The substrate may be a porous body or a dense body, but considering the integrity with the surface layer, at least the surface layer to be coated is preferably porous. In addition, the form of the base material 4 can take various forms according to a use.

(Composite form of base material and oxidation-resistant material in composite material)
An example of the composite form of the oxidation resistant material and the base material in this composite material is shown in FIG. The composite material 12a in FIG. 2A shows a form in which the base material 14 is covered with an oxidation resistant layer 16a. The oxidation-resistant layer 16a is formed as a film made of a single phase 18 of proton conductive material. According to this embodiment, by contacting oxygen on the surface of the oxidation resistant layer 16a, oxygen is taken in as oxygen ions (effective charge 0) at normal lattice positions in the oxidation resistant layer 16a, and holes are simultaneously generated. Further, by contacting with water vapor, the reaction between the holes in the oxidation-resistant layer 16a and the water vapor causes protons to work in the oxidation-resistant layer 16a and generate oxygen molecules. Further, oxide ions (effective charge 0) are taken into the regular lattice positions in the oxidation-resistant layer 16a by the reaction between oxygen vacancies and water vapor, and at the same time, protons are taken in between the lattices. Thus, when protons are taken from the external environment, the protons diffuse inward at a lower concentration. In any case, the anionization of oxygen and water vapor on the surface of the oxidation resistant layer 16a is suppressed. In addition, in the oxidation-resistant layer 16a, proton conduction and / or hole conduction is mainly used, so that oxygen ions are passed through the material by oxygen ion conduction and / or electron conduction at high temperatures as seen in conventional oxides. Inward diffusion is suppressed. Furthermore, the proton concentration increases in the vicinity of the interface with the base material 14 by diffusing protons inward due to proton conductivity, so that the oxidation of the base material 14 is further suppressed. With these, excellent oxidation resistance can be obtained.

  The composite material 12b shown in FIG. 2B includes an oxidation resistant layer 16b shown in FIG. The oxidation-resistant layer 16b is composed of a laminated structure of a proton conductive material phase 18 and an aprotic conductive material phase 20, and the aprotic conductive material phase 20 is formed on the surface layer side. Since the aprotic conductive material phase 20 is mainly composed of oxygen ion conduction and / or electron conduction, it is oxygen ions that diffuse in the aprotic conductive material phase 20 and proton diffusion does not occur or is not significant. It is suppressed. Therefore, in the proton conductive material phase 18, holes are mainly generated and protons are hardly generated. Therefore, when the base material 14 has reactivity with protons, the structure of the composite material 12b suppresses the reaction between the base material 14 and protons. Moreover, even if these oxygen ions reach the proton conductive material phase 18, the diffusion of oxygen ions in the phase 18 is blocked. For this reason, the oxidation of the base material 14 is also satisfactorily suppressed.

  The composite material 12c shown in FIG. 2 (c) is composed of a laminated structure of the proton conductive material phase 18 and the aprotic conductive material phase 20 with respect to the base material 14 as in FIG. 2 (b). An oxidation resistant layer 16c is provided. Unlike FIG.2 (b), the proton conductive material phase 18 is located more on the surface layer side. Since the base material 14 and the proton conductive material phase 18 are not in direct contact with each other, when the two components are reactive with each other, the reaction can be suppressed and the chemical stability of the two can be ensured. Further, when the base material 14 is reactive with protons, the protons that have diffused in the proton conductive material phase 18 are blocked at the interface with the non-proton conductive material phase 20, so And the chemical stability of the substrate 14 can be ensured. In these cases, it is preferable that the aprotic conductive material phase 20 has low reactivity or does not have any reactivity with the base material 14 and the proton conductive material phase 18. Furthermore, the aprotic conductive material phase 20 is configured to have a thermal expansion coefficient that is intermediate between the thermal expansion coefficients of the base material 14 and the proton conductive material phase 18, so that the base material 14 and the oxidation-resistant layer 16 c The difference in thermal expansion coefficient can be relaxed.

  The composite material 12d shown in FIG. 2 (d) includes an oxidation resistant layer 16d having a composite structure in which the proton conductive material phase 18 is a matrix and the aprotic conductive material phase 20 is a dispersed phase. Yes. According to the composite material 12d, by providing the oxidation resistant layer 16d having a composite structure, it is possible to effectively exhibit the action of suppressing the diffusion of oxygen ions, and the proton conductive material phase 18 and the aprotic conductive material phase 20 are used. Both functions can be expressed while improving adhesiveness. Moreover, since the diffusion of protons is suppressed by using a composite structure, the reactivity between the base material 14 and protons is also suppressed. Furthermore, a thermal expansion coefficient can be adjusted by setting it as a composite structure. As already described, the oxidation resistant layer 16d may have a gradient composition. In this composite form, the reactivity between the aprotic conductive material phase 20 and the substrate 14 is effectively suppressed.

  A composite material 12e shown in FIG. 2 (e) includes an oxidation resistant material 16e having a non-proton conductive material phase 20 as a matrix and a proton conductive material phase 18 as a dispersed phase with respect to the base material 14. According to this composite material 12e, the reactivity between the proton conductive material phase 18 and the base material 14 is effective instead of the reactivity between the aprotic conductive material phase 20 and the base material 14 being effectively suppressed. Except for being suppressed, it is possible to obtain the same effects as those described in FIG.

  The composite material 12f shown in FIG. 2 (f) has a first oxidation-resistant layer 22 composed of the proton conductive material phase 18 in order from the surface layer side, the proton conductive material phase 18, and the aprotic conductivity with respect to the base material 14. The second oxidation-resistant layer 24 made of the conductive material phase 20 and the third oxidation-resistant layer 26 made of the aprotic conductive material phase 20 are provided. This multilayer structure as a whole has a gradient composition in which the proton conductive material is distributed from a high concentration to a low concentration from the surface layer side to the inner layer side, and the aprotic conductive material is distributed from a low concentration to a high concentration. It can be said that.

  In this composite material 12f, the generation and adsorption of anion species (oxygen ions and hydroxyl ions) and the proton conductive material phase 18 that suppresses the inward diffusion of oxygen ions are provided on the surface layer side, so that the corrosive species are generated on the surface layer side. By blocking and efficiently suppressing oxidation, and by providing a third oxidation-resistant layer 26 composed of the second oxidation-resistant layer 24 and the aprotic conductive material phase 20 having a dispersed structure on the inner side, the proton and the base material are provided. 14 can be suppressed, the adhesion between the layers can be secured, and the difference in thermal expansion coefficient can be reduced. As shown in FIG. 2 (f), the second oxidation resistant layer 24 has an oxidation resistant layer 24 a having a proton conductive material phase 18 as a matrix and an aprotic conductive material phase 20 as a dispersed phase, as shown in FIG. And the oxidation-resistant layer 24b having the proton conductive material phase 18 as a dispersed phase and the non-proton conductive material phase 20 as a matrix, the concentration of the proton conductive material is high on the surface layer side, and the inner layer side is By constructing a gradient composition that increases the concentration of the aprotic conductive material, the adhesion to the surface layer side and the inner layer side, the thermal expansion coefficient, and the like can be easily adjusted. The gradient composition is not limited to such a discontinuous one but may be a continuous one.

  In addition, in the composite material 12f in FIG. 2 (f), the oxidation-resistant layer 22 made of the proton conductive material phase 18 is formed on the surface layer side. However, the composite material 12f is made of the non-proton conductive material phase 20 in order from the surface layer side. A third oxidation-resistant layer 26, a second oxidation-resistant layer 24 composed of a proton conductive material phase 18 and an aprotic conductive material phase 20, and a first oxidation-resistant layer 22 composed of a proton conductive material phase 18. Can also be provided. By doing so, it is possible to construct an oxidation resistant layer having a gradient composition having a concentration distribution opposite to that of the composite material 12f.

The outermost layer of the composite material can be provided with a heat shielding layer. By providing the heat shielding layer, the surface layer side, that is, the proton conductive material phase or the aprotic conductive material phase can be shielded from the external temperature, and the reactivity can be suppressed to contribute to the suppression of oxidation. Various low thermal conductive ceramics can be used as the material of the heat shielding layer. For example, stabilized or partially stabilized zirconia can be used, and those using Y ₂ O ₃ , Sc ₂ O ₃ , Er ₂ O ₃ , La ₂ O ₃ , MgO, CaO and CeO ₂ as stabilizing materials. Can be preferably used. These can be used alone or in combination of two or more as stabilizing materials.

  In these various forms of the composite material, to improve the adhesion between the base material 14 and the proton conductive material phase and / or the aprotic conductive material phase applied to the surface, and / or to reduce the difference in thermal expansion coefficient. For this purpose, a binder phase can be interposed between the base material and these material phases as required.

  The composite material can be manufactured using a conventionally known method for manufacturing ceramics in the same manner as the oxidation resistant material. In the laminated composite form of the composite material, it is particularly preferable to laminate each layer by a thermal spraying method such as a plasma spraying method, a physical vapor deposition method (PVD) and / or a chemical vapor deposition method (CVD). According to the thermal spraying method, the physical vapor deposition method, and the chemical vapor deposition method, a multilayer laminated structure and a gradient composition structure can be easily constructed, and the film thickness control is relatively easy.

  The oxidation-resistant material and the composite material described above are preferable as a structural member used in a high temperature environment or an oxidation-resistant film thereof. Preferably, it is used in a high temperature environment of 1100 ° C. or higher, more preferably 1300 ° C. or higher, and further preferably 1500 ° C. or higher. The oxidation resistant material and the composite material are preferably used under an environment of 1800 ° C. or lower. Structural members include gas turbine members applied to cogeneration systems and the like, such as support shafts, moving blades, stationary blades, combustors, gas pipes in turbines, jet engine structural members, and rockets. It can use for structural members, such as the outer wall material of a moving body outside the atmosphere. It can be used for an uncooled gas turbine system having a gas turbine inlet temperature of 1500 ° C. or higher.

  Examples of the present invention will be specifically described below. In addition, these Examples are for demonstrating this invention, and do not limit this invention.

In this example, a composite material having a laminated structure shown in FIG. 3A was produced and its oxidation resistance was evaluated.
(1) The _{Carbon-SiC-YSi x / SiC} -Y 2 SiO 5 Substrate Preparation substrates, _{Carbon-SiC-YSi} are examined as oxidation coating of _{Carbon x / SiC-Y 2 SiO} 5 multilayer structure Using the body. Since LaPO ₄ ceramics react with carbon, this multilayer structure was adopted from the viewpoint of preventing reaction. The base material was prepared in accordance with the method of Kondo et al. (Masayuki Kondo, Ken Komine, Tatsuo Morimoto, Kei Tomohiro, Journal of the Japan Institute of Metals, 63, 851-858 (1999). Using a sample (Carbon-SiC) coated with SiC (thickness: 100 μm) by a CVD method on a substrate (φ20 × 5 mm), Y ₂ O ₃ powder dispersed in an ethanol solvent and slurried is about 100 μm thick After that, heat treatment was performed in vacuum at 1600 ° C. for 1 hour to form a YSi _x / SiC layer on the surface of the CVD-SiC layer, and then the surface of the Carbon-SiC—YSi _x / SiC layer. _.Y 2 SiO ₅ powder of _Y 2 SiO ₅ powder to form a protective film layer using a raw material by atmospheric plasma spraying method, the silicon alkoxide and yttrium alkoxy A fine powder produced by co-precipitation of a mixed solution of aluminum was processed in the atmosphere at 1000 ° C. for 1 hour, and APS7050 made by Aeroplasma was used as the thermal spraying device, the output was 25.6 kW, the powder The supply amount was 30 g / min, and the spraying distance (distance from the powder supply nozzle to the base material) was 120 mm.

(2) Preparation of La _0.99 Ba _0.01 PO ₄ powder An aqueous solution of (NH ₄ ) ₂ HPO ₄ , La (NO ₃ ) ₃ , Ba (NO ₃ ) _{2 was} prepared as La: Ba: P = 0.99: The precipitate obtained by adjusting to 0.01: 1 (molar ratio) and coprecipitating was filtered and calcined at 800 ° C. for 5 hours in the atmosphere. The obtained calcined powder was pulverized to obtain La _0.99 Ba _0.01 PO ₄ powder.

₍₃₎ thermal expansion coefficient of the fabrication La _0.99 Ba _0.01 PO ₄ and _Y 2 SiO ₅ of _{Carbon-SiC-Y 2 SiO 5} -La 0.99 Ba 0.01 PO 4 , respectively, 10 × 10 ^Since these are greatly different from ⁻⁶ ° C. ⁻¹ and 3 to 4 × 10 ⁻⁶ ° C. ⁻¹ , when these are directly joined, interface peeling occurs in the cooling process after film formation. Therefore, a gradient composition layer is provided between these layers, and these are blended so as to reduce the interface residual stress induced by the difference in thermal expansion coefficient. That is, two kinds of La _0.99 Ba _0.01 PO ₄ powder and Y ₂ SiO ₅ powder are mixed at a ratio (volume ratio) of 3: 7 (mixed powder A) and 7: 3 (mixed powder B). A mixed powder was prepared. Next, Y ₂ SiO ₅ , mixed powder A, mixed powder B, and La _0.99 Ba _0.01 PO ₄ were formed in this order on the surface of the Carbon-SiC-YSi _x / SiC layer by atmospheric plasma spraying. The film forming conditions were the same as those in the Y ₂ SiO ₅ layer in (1). The film thickness of each layer was 25 μm, and an oxide film of a total of 100 μm was provided on the Carbon-SiC—YSi _x / SiC layer to obtain a sample of Example 1 (FIG. 3A). In addition, as a comparative material, a carbon-SiC-YSi _x / SiC layer provided with a Y ₂ SiO ₅ single layer with a thickness of 100 μm by a plasma spraying method under the same film forming conditions was also produced. An oxidation test was performed (see FIG. 3B).

(4) Evaluation of corrosion resistance After the sample was treated for 1 h in oxygen-water vapor at 1500 ° C. (100 ml / min, water vapor concentration = 80 vol%), the structural change of the sample cross section was observed. As a result, in the case of the Y ₂ SiO ₅ single layer sample (FIG. 3B), the YSi _x / SiC layer was oxidized by about 50 μm, whereas the La _0.99 Ba _0.01 PO ₄ layer was In the applied sample of Example 1 (FIG. 3A), the YSi _x / SiC layer was hardly oxidized. From this, it was found that the oxidation resistance was improved at 1500 ° C. by applying the La _0.99 Ba _0.01 PO ₄ layer to the surface.

In this example, a composite material having a laminated structure shown in FIG. 4A was produced and its oxidation resistance was evaluated.
(1) Preparation of Carbon-TaC-ScTaO ₄ base material Around the Carbon substrate used in Example 1, TaC powder (manufactured by Koyo Chemical Co., TAO-01PB) was filled and press-molded (20 MPa), followed by hot pressing. Firing was performed (2180 ° C. × 1 h, Ar, 40 MPa). The obtained multilayer structure was composed of a Carbon-TaC layer, and the Carbon layer had a diameter of 20 mm × 5 mm, and a TaC layer having a thickness of about 500 μm was formed around it. Next, a protective film layer was formed on the surface of the Carbon-TaC layer using ScTaO ₄ powder as a raw material by an atmospheric plasma spraying method. Here, APS7050 made from Aeroplasma was used for the thermal spraying apparatus. The output was 25.6 kW, the powder supply amount was 30 g / min, and the spraying distance (distance from the powder supply nozzle to the base material) was 120 mm. The adjustment method of ScTaO ₄ powder were as follows. Ball mill mixing (24 hrs) of Ta ₂ O ₅ powder (manufactured by Koyo Chemical Co., TAO-01PB) and Sc ₂ O ₃ powder (manufactured by Daiichi rare element chemical industry) at a molar ratio of 1: 1, followed by press molding (5 MPa ) And calcined (1400 ° C. × 5 h, in Air). In order to homogenize the raw material, pulverization → press molding → heat treatment was repeated three times to obtain ScTaO ₄ powder.

_{(2) Carbon-TaC-ScTaO} 4 -La 0.99 Ba 0.01 thermal expansion coefficient of the fabrication La _{of 0.99} Ba _0.01 PO ₄ and ScTaO ₄ of PO ₄ are each ¹⁰ × 10 ^-6 ℃ ^-1 And 5 * 10 <^{-6> [} deg.] C.- ¹ greatly differ, and when these are directly joined, interface peeling occurs in the cooling process after film formation. Therefore, a gradient composition layer was provided between these layers to prepare a mixed powder so as to reduce the interface residual stress induced by the difference in thermal expansion coefficient. That is, two kinds of mixed powders were prepared with a mixing ratio (volume ratio) of La _0.99 Ba _0.01 PO ₄ powder and ScTaO ₄ powder of 3: 7 (mixed powder C) and 7: 3 (mixed powder D). did. Next, ScTaO ₄ , mixed powder C, mixed powder D, and La _0.99 Ba _0.01 PO ₄ were formed in this order on the surface of the Carbon-TaC layer by atmospheric plasma spraying. The film forming conditions were the same as those for the Y ₂ SiO ₅ layer in (1). The thickness of each layer was 25 μm, and an oxide film having a total thickness of 100 μm was applied on the Carbon-TaC layer to obtain a sample of Example 2 (FIG. 4A). Further, as a comparative material, a material obtained by applying an ScTaO ₄ single layer on a Carbon-TaC layer to a thickness of 100 μm by the atmospheric plasma spraying method under the same film forming conditions as above (FIG. 4B) is also produced. The following oxidation test was conducted.

(3) Evaluation of corrosion resistance After the sample was treated in oxygen-water vapor at 1500 ° C. (100 ml / min, water vapor concentration = 80 vol%) for 1 h, the structural change of the sample cross section was observed. As a result, in the case of the ScTaO ₄ single layer sample (FIG. 3B), the TaC layer was oxidized by about 10 μm, whereas the La _0.99 Ba _0.01 PO ₄ layer was applied. In the sample (FIG. 4A), the TaC layer was hardly oxidized. From this, it was found that the oxidation resistance was improved at 1500 ° C. by applying the La _0.99 Ba _0.01 PO ₄ layer to the surface.

In this example, a composite material having a laminated structure shown in FIG. 5A was produced, and its oxidation resistance was evaluated.
(1) Production of NiCoCrAlY—Al ₂ O ₃ Substrate A NiCoCrAlY plate (φ20 mm × 5 mm) produced by low-pressure plasma spraying was heat-treated at 1050 ° C. for 5 hours in Ar. As a result, the Al component in NiCoCrAlY was preferentially oxidized, and a dense Al ₂ O ₃ film (about 1 μm) was formed on the NiCoCrAlY surface.

(2) Preparation of La _0.95 Sr _0.05 PO ₄ Powder An aqueous solution of (NH ₄ ) ₂ HPO ₄ , La (NO ₃ ) ₃ , and Sr (NO ₃ ) _{2 was} prepared using La: Sr: P = 0.95. : 0.05: 1 (molar ratio), the precipitate obtained by coprecipitation was filtered, and calcined in the atmosphere at 800 ° C. for 5 hours. The obtained calcined powder was pulverized to obtain La _0.95 Sr _0.05 PO ₄ powder.

(3) Production of NiCoCrAlY—Al ₂ O ₃ —La _0.95 Sr _0.05 PO ₄ La _0.95 Sr _0.05 PO ₄ layer (thickness) was formed on the surface of the NiCoCrAlY—Al ₂ O ₃ layer by atmospheric plasma spraying. 50 μm) was formed into a sample of Example 3 (FIG. 5A). The film forming conditions were the same as those for the Y ₂ SiO ₅ layer in (1). In addition, as a comparative material, a NiCoCrAlY-Al ₂ O ₃ layer on which an Al ₂ O ₃ single layer was applied to a thickness of 50 μm by an atmospheric plasma spraying method (FIG. 5B) was also produced. Tested.

(4) Corrosion resistance evaluation After the sample was treated in oxygen-water vapor at 1100 ° C (100 ml / min, water vapor concentration = 80 vol%) for 100 h, the structural change of the sample cross section was observed. As a result, in the case of the Al ₂ O ₃ single layer sample (FIG. 5B), the NiCoCrAlY oxidation progressed, and the thickness of the Al ₂ O ₃ layer increased to about 10 μm. In the sample to which the La _0.95 Sr _0.05 PO ₄ layer was applied (FIG. 4A), the thickness of the Al ₂ O ₃ layer was hardly changed. From this, it was found that the oxidation resistance was improved at 1100 ° C. by applying the La _0.95 Sr _0.05 PO ₄ layer to the surface.

It is a figure which shows the various forms (a)-(e) of the oxidation-resistant material of this invention. It is a figure which illustrates various forms (a)-(f) of the composite material of this invention. It is a figure which shows the laminated structure (a) of the composite material of Example 1, and the laminated structure (b) of a comparative material. It is a figure which shows the laminated structure (a) of the composite material of Example 1, and the laminated structure (b) of a comparative material. It is a figure which shows the laminated structure (a) of the composite material of Example 1, and the laminated structure (b) of a comparative material.

Explanation of symbols

  2a, 2b, 2c, 2d, 2e Oxidation resistant material, 4 proton conductive material phase, 6 other material phase, 12a, 12b, 12c, 12d, 12e, 12f composite material, 16a, 16b, 16c, 16d, 16e, 16f oxidation-resistant layer, 18 proton conductive material phase, 20 aprotic conductive material phase, 22 first oxidation-resistant layer, 24 second oxidation-resistant layer, 24a, 24b are constituent elements of the second oxidation-resistant layer Oxidation-resistant layer, 26 Third oxidation-resistant layer.

Claims (15)

La _1-X Me _X (PO ₄ ) (where Me is a divalent metal atom and 0 <X ≦ 0.1) and an oxide-based proton conductive material phase and an oxide-based non-oxide An oxidation resistant material, which is a sintered body comprising a proton conductive material phase . The oxide proton conductive _{material, La 1-X Me X (} PO 4) ( although, Me is a divalent metal atom, a 0 <X ≦ 0.1.) Is, according to claim 1 An oxidation-resistant material as described in 1. The oxidation-resistant material according to claim 2 , wherein the divalent metal atom is one or more metal atoms selected from the group consisting of Mg, Ca, Sr and Ba. The said sintered compact is an oxidation-resistant material in any one of Claims 1-3 provided with the laminated structure of the said oxide type proton conductive material phase and the said oxide type aprotic conductive material phase. The oxidation-resistant material according to claim 1, wherein the sintered body includes a dispersed structure of the oxide-based proton conductive material phase and the oxide-based aprotic conductive material phase. The oxide-based aprotic conductive materials are Ta ₂ O ₅ , Al ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , SiO ₂ , TiO ₂ , Al ₆ Si ₂ O ₁₃ (mullite), Y ₂ SiO ₅ , LaPO _4, LaAlO _3, and is one or more selected from the group consisting of ScTaO _4, oxidation material according to any one of claims 1 to 5. The oxidation-resistant material according to claim 6 , wherein the oxide-based aprotic conductive material is Ta ₂ O ₅ , Al ₂ O ₃ , Y ₂ O ₃ , Y ₂ SiO _5, or ScTaO ₄ . The oxidation-resistant material according to any one of claims 1 to 7 , which is used for oxidation resistance under a temperature environment of 1100 ° C or higher. A composite material,
A non-oxide base material;
An oxidation-resistant layer made of the oxidation-resistant material according to any one of claims 1 to 8 , which is located on the surface layer side of the substrate;
A composite material comprising: A composite material,
A non-oxide base material;
An oxidation resistant layer located on the surface side of the substrate;
With
The oxidation resistant layer is
_{First comprising} an oxide-based proton conductive material phase of La _1-X Me _X (PO ₄ ) (where Me is a divalent metal atom and 0 <X ≦ 0.1). A second oxidation-resistant layer comprising an oxidation-resistant layer, the oxide-based proton conductive material phase and the oxide-based aprotic conductive material phase; and a third layer comprising the oxide-based aprotic conductive material phase. A composite material containing an oxidation resistant layer. The composite material according to claim 10 , wherein the second oxidation-resistant layer has a gradient composition of the oxide-based proton conductive material phase and the oxide-based aprotic conductive material phase. The oxide proton conductive _{material, La 1-X Me X (} PO 4) ( although, Me is a divalent metal atom, a 0 <X ≦ 0.1.) Is, according to claim 10 Or the composite material of 11 . The composite material according to claim 12 , wherein the divalent metal atom is one or more selected from the group consisting of Mg, Ca, Sr and Ba. The composite material according to any one of claims 9 to 13 , wherein the non-oxide base material is made of one or both of a carbon-based material and a metal. The composite material according to any one of claims 9 to 14 , which is a structural member used in a temperature environment of 1100 ° C or higher.

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