JP2019214750A - Environmental barrier coating, environmental barrier component with the same, and method of manufacturing environmental barrier coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an environment resistant coating capable of maintaining good environment resistant performance for a long period of time. SOLUTION: The resistance is formed on a base material 1 containing a ceramic matrix composite material as a main component and includes an outermost surface layer 2 and at least one intermediate layer 2 arranged between the base material 1 and the outermost surface layer 2. In the environmental coating 10, the outermost layer 2 is composed of rare earth-stabilized zirconia, contains 95% by mass or more of ytterbium-stabilized zirconia, and the first intermediate layer 3a in contact with the outermost layer 2 is a rare earth-stabilized zirconia or a rare earth-stabilized zirconia. The ytterbium content of the first intermediate layer 3a is 90 mol% or more, containing at least one rare earth compound of the silicates. [Selection diagram] Figure 1

Description

  The present disclosure relates to an environmental coating, an environmental component including the same, and a method of manufacturing the environmental coating.

Ceramic-based composite materials (silicon carbide fiber reinforced silicon carbide material (SiC-SiC), carbon fiber reinforced silicon carbide material (C-SiC), etc.) are lightweight and have good mechanical properties at high temperatures. Therefore, ceramic-based composite materials are promising materials as high-temperature members for aircraft engines, industrial gas turbines, and the like. However, in a high-temperature and high-pressure steam oxidation environment where steam is present, corrosion and wall thinning due to steam occur along with oxidation. For this reason, especially in a gas turbine combustion environment, durability is significantly reduced due to high-temperature and high-pressure steam oxidation. Therefore, for practical use in a gas turbine combustion environment, it is preferable to apply an environment-resistant coating having durability (environment-resistant performance) to high-temperature and high-pressure steam. For this reason, materials coated with rare earth silicates (Y ₂ Si ₂ O ₅ , Y ₂ Si ₂ O _7, etc.) are being developed as materials for environmentally resistant coatings.

However, even when a rare earth silicate is used, silicon is volatilized by the reaction between water vapor and SiO _2, and the reduction in thickness of the environmentally resistant coating cannot be ignored. Also, rare earth silicates do not have sufficient erosion characteristics at high temperatures. Therefore, a technique described in Patent Literature 1 has been proposed for suppressing wall thinning and improving erosion characteristics. Patent Literature 1 describes an environment-resistant coating formed on a substrate made of a ceramic-based composite material. The environment-resistant coating includes an outermost layer including ytterbia-stabilized zirconia, and an intermediate layer formed between the outermost layer and the base material, the intermediate layer including rare earth silicate.

WO 2016/129588 (see especially the examples)

  Ytterbia stabilized zirconium has excellent mechanical properties at high temperatures. Further, ytterbia-stabilized zirconium hardly reacts with water vapor and hardly volatilizes. Therefore, suppression of wall thinning can be expected even in the presence of steam.

  However, in the environment-resistant coating described in Patent Document 1, when the environment-resistant coating is repeatedly exposed to high heat, ytterbium in the outermost layer thermally diffuses into the intermediate layer. As a result, the concentration of ytterbium in the outermost layer decreases, and the phase stability of the outermost layer decreases. Thereby, for example, phase transformation easily occurs in a region exceeding 1300 ° C., and the environment-resistant coating is easily deteriorated.

  An object of at least one embodiment of the present invention is to provide an environment-resistant coating capable of maintaining good environment-resistant performance for a long period of time, an environment-resistant component including the same, and a method of manufacturing the environment-resistant coating.

(1) An environment-resistant coating according to an embodiment of the present invention includes:
An environment-resistant coating formed on a base material including a ceramic-based composite material as a main component and including an outermost layer and at least one intermediate layer disposed between the base material and the outermost layer,
The outermost layer is composed of rare earth stabilized zirconia, and contains 95% by mass or more of ytterbia stabilized zirconia,
The first intermediate layer in contact with the outermost layer includes a rare earth compound that is at least one of rare earth stabilized zirconia and rare earth silicate,
The content of ytterbium in the first intermediate layer is at least 90 mol% with respect to the entire rare earth element in the first intermediate layer.

  According to the configuration (1), thermal diffusion of ytterbium from the outermost layer to the first intermediate layer can be suppressed, and the phase stability of the outermost layer can be maintained in a high state. Thus, an environment-resistant coating capable of maintaining good environment-resistant performance for a long time can be provided.

(2) In some embodiments, in the configuration of (1) above,
The first intermediate layer contains at least rare earth stabilized zirconia.

  According to the above configuration (2), the content of the rare earth silicate in the first intermediate layer can be reduced, and deterioration of the first intermediate layer due to the reaction between the water vapor and the silicate can be suppressed.

(3) In some embodiments, in the above configuration (1) or (2),
The thermal expansion coefficient of the first intermediate layer is not less than 8 × 10 ⁻⁶ / K and not more than 10 × 10 ⁻⁶ / K.

  According to the above configuration (3), the thermal expansion coefficient of the first intermediate layer can be made smaller than that of the outermost layer, and the thermal stress can be reduced.

(4) In some embodiments, in any one of the above configurations (1) to (3),
The at least one intermediate layer includes a second intermediate layer that contacts the first intermediate layer and includes a second intermediate layer disposed on the side of the substrate.
The thermal expansion coefficient of the second intermediate layer is smaller than the thermal expansion coefficient of the first intermediate layer.

  According to the configuration (4), the thermal expansion coefficient of the second intermediate layer can be made smaller than the thermal expansion coefficients of the outermost layer and the first intermediate layer, and the thermal stress can be reduced.

(5) In some embodiments, in the configuration of the above (4),
The thermal expansion coefficient of the second intermediate layer is not less than 5 × 10 ⁻⁶ / K and not more than 7 × 10 ⁻⁶ / K.

  According to the configuration (5), the thermal expansion coefficient of the second intermediate layer can be made smaller than the thermal expansion coefficients of the outermost layer and the first intermediate layer, and the thermal stress can be reduced.

(6) In some embodiments, in the configuration of the above (4) or (5),
The second intermediate layer includes ytterbia silicate and yttria silicate,
The yttrium concentration in the second intermediate layer is higher than the yttrium concentration in the first intermediate layer.

  According to the configuration of (6), since the second intermediate layer does not contact the outermost layer, the thermal diffusion of yttrium in the second intermediate layer to the outermost layer can be suppressed. Thereby, the phase stability of the outermost layer can be maintained high. Furthermore, compared to the case where the whole of the second intermediate layer is made of ytterbium, the production cost of the environment-resistant coating can be reduced by including the relatively inexpensive yttrium.

(7) In some embodiments, in any one of the above (1) to (6),
The first intermediate layer contains the rare earth compound in an amount of 95% by mass or more.

  According to the configuration of (7), environmental resistance can be improved.

(8) In some embodiments, in any one of the above (1) to (7),
The ceramic-based composite material includes at least one of a silicon carbide fiber reinforced silicon carbide material and a carbon fiber reinforced silicon carbide material.

  According to the configuration of (8), the strength of the base material can be improved.

(9) The environment-resistant component according to one embodiment of the present invention includes:
A base material containing a ceramic-based composite material as a main component,
An environment-resistant coating according to any one of the above (1) to (8), comprising: an environment-resistant coating formed on the substrate.

  According to the configuration (9), thermal diffusion of ytterbium from the outermost layer to the first intermediate layer can be suppressed, and the phase stability of the outermost layer can be maintained in a high state. Thereby, it is possible to provide an environment-resistant component capable of maintaining good environmental performance for a long time.

(10) The method for producing an environment-resistant coating according to one embodiment of the present invention includes:
What is claimed is: 1. A method for producing an environment-resistant coating comprising a top surface layer, and at least one intermediate layer disposed between the base material and the top surface layer, on a base material containing a ceramic-based composite material as a main component, ,
A first intermediate layer that is in contact with the outermost layer and includes a rare earth compound that is at least one of rare earth stabilized zirconia or a rare earth silicate, and the content of ytterbium is reduced with respect to the entire rare earth element in the first intermediate layer. A first intermediate layer manufacturing step of manufacturing the first intermediate layer that is 90 mol% or more;
An outermost layer manufacturing step of manufacturing the outermost layer made of rare earth-stabilized zirconia and containing 95% by mass or more of ytterbia-stabilized zirconia.

  According to the above configuration (10), thermal diffusion of ytterbium from the outermost layer to the first intermediate layer can be suppressed, and the phase stability of the outermost layer can be maintained in a high state. This can provide a method for producing an environment-resistant coating capable of maintaining good environmental performance for a long period of time.

  At least one embodiment of the present invention can provide an environment-resistant coating capable of maintaining good environmental performance for a long period of time, an environment-resistant component including the same, and a method of manufacturing the environment-resistant coating.

1 is a cross-sectional view of an environment-resistant coating according to an embodiment of the present invention. The volume ratio of YbSZ to the total volume of YbSZ and _Yb 2 SiO ₅ (horizontal axis) is a graph showing the relationship between the thermal expansion coefficient (vertical axis). (Y, _Yb) 2 SiO ₅ and _(Y, Yb) _(Y, Yb) to the total volume of 2 _Si 2 _{O 7} as the volume ratio of 2 _Si 2 _{O 7} (horizontal axis), the thermal expansion coefficient (vertical axis) 6 is a graph showing the relationship of. 1 is a flowchart illustrating a method for manufacturing an environment-resistant coating according to an embodiment of the present invention.

  Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the contents described in the following embodiments or the contents described in the drawings are merely examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, each embodiment can be implemented by arbitrarily combining two or more. Further, in each embodiment, the same members are denoted by the same reference numerals, and overlapping description will be omitted for simplification of the description.

The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  FIG. 1 is a cross-sectional view of an environment-resistant coating 10 according to one embodiment of the present invention. The environment-resistant coating 10 is formed on the substrate 1, and includes an outermost layer 2, at least one intermediate layer 3 disposed between the substrate 1 and the outermost layer 2, and a bond coat 4. Including. The intermediate layer 3 is, for example, a first intermediate layer 3a in contact with the outermost layer 2 and a second intermediate layer 3b in contact with the first intermediate layer 3a, and the second intermediate layer 3b arranged on the side of the base material 1 And The intermediate layer 3 may be only one layer or three or more layers. Moreover, the environment-resistant coating 10 is supported by the substrate 1 by disposing the bond coat 4 on the substrate 1.

  The substrate 1 is for supporting the environment-resistant coating 10. The base material 1 contains a ceramic-based composite material as a main component. The term “main component” as used herein refers to usually 50% or more, preferably 70% or more, more preferably 90% or more, and particularly preferably 95% or more, of the substrate 1 on a volume basis.

  The ceramic matrix composite (Ceramic Matrix Composites) includes, for example, at least one of a silicon carbide fiber reinforced silicon carbide material (SiC-SiC) and a carbon fiber reinforced silicon carbide material (C-SiC). By including at least one of SiC-SiC and C-SiC, the strength of the substrate 1 can be improved.

The coefficient of thermal expansion of the substrate 1 is preferably smaller than the coefficient of thermal expansion of each layer constituting the environment-resistant coating 10 described later. Specifically, the thermal expansion coefficient of the substrate 1 is preferably, for example, not less than 3.5 × 10 ⁻⁶ / K and not more than 4.5 × 10 ⁻⁶ / K. The thermal expansion coefficient can be measured based on, for example, JIS R 1618: 2002. In addition, in this specification, a "thermal expansion coefficient" means the thermal expansion coefficient measured when changing temperature from room temperature (25 degreeC) to 1200 degreeC.

  The thickness of the substrate 1 is not particularly limited, and may be appropriately determined according to the type of the environment-resistant component on which the environment-resistant coating 10 is formed.

The outermost layer 2 is made of rare earth stabilized zirconia and contains 95% by mass or more of ytterbia stabilized zirconia (Yb ₂ O ₃ stabilized ZrO ₂ , hereinafter referred to as YbSZ). By being composed of rare earth stabilized zirconia containing YbSZ in a proportion of 95% by mass or more, the reliability of the outermost layer 2 can be improved. Specifically, the phase stability of the outermost layer 2 is enhanced, and phase transformation can be suppressed even in a high temperature region of, for example, 1300 ° C. or more. Therefore, the heat cycle characteristics can be improved. In addition, thinning can be suppressed by suppressing the reaction with steam. For this reason, steam resistance can be improved.

As described above, YbSZ contained in the outermost layer 2 is zirconia (ZrO ₂ ) stabilized with ytterbia (Yb ₂ O ₃ ). Of the total mass of YbSZ, the mass of Yb ₂ O ₃ is preferably from 8% by mass to 27% by mass, more preferably about 17% by mass. When Yb ₂ O ₃ is contained in this mass range, an advantage of excellent thermal shock resistance and erosion resistance can be obtained.

  The thickness of the outermost layer 2 is preferably, for example, 10% or more and 50% or less of the entire environment-resistant coating 10. By doing so, there is obtained an advantage that both steam resistance and heat cycle characteristics are compatible.

  The intermediate layer 3 contains a rare earth compound which is at least one of rare earth stabilized zirconia and rare earth silicate. The intermediate layer 3 includes a first intermediate layer 3a in contact with the outermost layer 2, a second intermediate layer 3b in contact with the first intermediate layer 3a, and a second intermediate layer 3b disposed on the base 1 side. including.

  The first intermediate layer 3a in contact with the outermost layer 2 contains a rare earth compound which is at least one of rare earth stabilized zirconia and rare earth silicate. The first intermediate layer 3a preferably contains a rare earth compound in an amount of 95% by mass or more. When the rare earth compound is contained in an amount of 95% by mass or more, environmental resistance performance can be improved.

The rare earth stabilized zirconia includes ytterbia stabilized zirconia (YbSZ). Examples of the rare earth silicate include, for example, rare earth monosilicate, and specific examples thereof include Y ₂ SiO ₅ , Yb ₂ SiO ₅ , and Lu ₂ SiO ₅ . Among these, Yb ₂ SiO ₅ (ytterbium monosilicate) is preferable.

  The first intermediate layer 3a preferably contains at least rare earth stabilized zirconia. By containing the rare earth stabilized zirconia, the content of the rare earth silicate in the first intermediate layer 3a can be reduced, and the deterioration of the first intermediate layer 3a due to the reaction between the water vapor and the silicate can be suppressed.

Further, the first intermediate layer 3a is preferably made of a material having excellent steam resistance, and specifically, is preferably a mixed phase containing both rare earth stabilized zirconia and rare earth silicate. Specifically, the first intermediate layer 3a is particularly preferably a mixed phase of YbSZ and Yb ₂ SiO ₅ .

  Further, the content of ytterbium in the first intermediate layer 3a is 90 mol% or more with respect to the entire rare earth in the first intermediate layer 3a. Thereby, the ytterbium concentration of the first intermediate layer 3a can be made close to the ytterbium concentration contained in the outermost layer 2, and the thermal diffusion of ytterbium can be suppressed.

  The thickness of the first intermediate layer 3a can be, for example, not less than 20 μm and not more than 300 μm.

The thermal expansion coefficient of the first intermediate layer 3a is preferably not less than 8 × 10 ⁻⁶ / K and not more than 10 × 10 ⁻⁶ / K. When the coefficient of thermal expansion is in this range, the coefficient of thermal expansion of the first intermediate layer 3a can be smaller than the coefficient of thermal expansion of the outermost layer 2, and the thermal stress can be reduced. The thermal expansion coefficient of the first intermediate layer 3a will be described with reference to FIG.

FIG. 2 is a graph showing the relationship between the volume ratio of YbSZ to the total volume of YbSZ and Yb ₂ SiO ₅ (horizontal axis) and the coefficient of thermal expansion (vertical axis). The thermal expansion coefficient when the ratio of YbSZ is 0, that is, the thermal expansion coefficient of Yb ₂ SiO ₅ is 7.4 × 10 ⁻⁶ / K. When the volume ratio of YbSZ increases, the coefficient of thermal expansion linearly increases.

As described above, the thermal expansion coefficient of the first intermediate layer 3a is preferably not less than 8 × 10 ⁻⁶ / K and not more than 10 × 10 ⁻⁶ / K. Therefore, the volume ratio of YbSZ is set to be 0.17 or more and 0.72 or less so that the thermal expansion coefficient becomes a target region (8 × 10 ⁻⁶ / K or more and 10 × 10 ⁻⁶ / K or less). Is preferred. The composition of the first intermediate layer 3a when the proportion of YbSZ is 0.17 is _Yb 2 _O 3 -18.2 _weight% ZrO 2 -10.3 wt% SiO _2, the proportion of YbSZ 0.72 In this case, the composition of the first intermediate layer 3a is Yb ₂ O ₃ -64.7% by mass ZrO ₂ -2.9% by mass SiO ₂ .

The thermal expansion coefficient of the first intermediate layer 3 a is preferably larger than the thermal expansion coefficient of the base material 1 and smaller than the thermal expansion coefficient of the outermost layer 2. The difference between the coefficient of thermal expansion of the first intermediate layer 3a and the coefficient of thermal expansion of the substrate 1 (including the bond coat 4 described later) is preferably 4 × 10 ⁻⁶ / K or less. Specifically, the thermal expansion coefficient of the first intermediate layer 3a is more preferably about 8.6 × 10 ⁻⁶ / K. Thereby, the thermal stress can be particularly reduced. The ratio of YbSZ at this time was 0.33, the composition of the first intermediate layer 3a is _Yb 2 _O 3 -33.5 _weight% ZrO 2 -7.9 wt% SiO _2.

  Returning to FIG. 1, the second intermediate layer 3b is included in the above-described intermediate layer 3, is in contact with the first intermediate layer 3a, and is disposed on the side of the base material 1.

The material of the second intermediate layer 3b is not particularly limited, rare earth silicates, mullite _{(3Al 2} O 3 -2SiO _2. Thermal expansion coefficient of 6 × ¹⁰ -6 / K), and the like. The rare earth silicate may be a rare earth monosilicate (Ln ₂ SiO ₅ ), a rare earth disilicate (Ln ₂ Si ₂ O ₇ ), or a mixed layer thereof. Here, Ln is a rare earth element, and examples thereof include Sc, Lu, Gd, Sm, Eu, Nd, Yb, and Y, and among them, Y is preferable. _Therefore, preferably _Y 2 SiO ₅ as Ln 2 SiO _5, preferably _Y 2 _Si 2 _{O 7} as Ln 2 _Si 2 _{O 7.}

The rare earth silicate may have improved phase stability by substituting a part of Y with rare earth (Ln). Among them, for example, a mixed phase of (Y, Ln) ₂ SiO ₅ and (Y, Ln) ₂ Si ₂ O ₇ is preferable. In this mixed phase, a material containing Yb as Ln is preferable. That is, the second intermediate layer 3b preferably contains ytterbium silicate (Yb ₂ SiO ₅ and Yb ₂ Si ₂ O ₇ ) and yttria silicate (Y ₂ SiO ₅ and Y ₂ Si ₂ O ₇ ).

  The yttrium concentration in the second intermediate layer 3b is preferably higher than the yttrium concentration in the first intermediate layer 3a. By doing so, since the second intermediate layer 3b does not contact the outermost layer 2, it is possible to suppress the thermal diffusion of yttrium in the second intermediate layer 3b to the outermost layer 2. Thereby, the phase stability of the outermost layer 2 can be kept high. Furthermore, by including relatively inexpensive yttrium as compared with the case where the entire second intermediate layer 3b is made of ytterbium, the manufacturing cost of the environment-resistant coating 10 can be reduced.

  The thickness of the second intermediate layer 3b can be, for example, not less than 20 μm and not more than 400 μm.

The thermal expansion coefficient of the second intermediate layer 3b is preferably smaller than the thermal expansion coefficient of the first intermediate layer 3a. Specifically, for example, the thermal expansion coefficient of the second intermediate layer 3b is preferably 5 × 10 ⁻⁶ / K or more and 7 × 10 ⁻⁶ / K or less. Thereby, the thermal expansion coefficient of the second intermediate layer 3b can be made smaller than the thermal expansion coefficients of the outermost layer 2 and the first intermediate layer 3a, and the thermal stress can be reduced.

The thermal expansion coefficient of the second intermediate layer 3b will be described with reference to FIG.
3, (Y, _Yb) 2 SiO ₅ and _(Y, Yb) and _(Y, Yb) to the total volume of 2 _Si 2 _{O 7} volume ratio of 2 _Si 2 _{O 7} (horizontal axis), the coefficient of thermal expansion ( 6 is a graph showing the relationship with the vertical axis). In this _graph, the mixed phases of _{(Y 0.8} Yb _0.2) and _{2 SiO 5 (Y 0.8 Yb 0.2} ) 2 Si 2 O 7, (Y 0.8 Yb 0.2 3) shows the change in the coefficient of thermal expansion when the volume ratio of ₂ Si ₂ O ₇ is changed. As shown in this graph, as the volume ratio of (Y _0.8 Yb _0.2 ) ₂ Si ₂ O ₇ increases, the thermal expansion coefficient decreases linearly.

As described above, the thermal expansion coefficient of the second intermediate layer 3b is preferably 5 × 10 ⁻⁶ / K or more and 7 × 10 ⁻⁶ / K or less. Therefore, the volume ratio of (Y _0.8 Yb _0.2 ) ₂ Si ₂ O ₇ is set so that the coefficient of thermal expansion becomes the target region (5 × 10 ⁻⁶ / K or more and 7 × 10 ⁻⁶ / K or less). It is preferable to make it 0.1 or more and 0.65 or less. When the ratio of (Y _0.8 Yb _0.2 ) ₂ Si ₂ O ₇ is 0.1, the composition of the second intermediate layer 3 b is Y ₂ O ₃ -22.2 mass% Yb ₂ O ₃ -26. .8 the _{mass% SiO 2, (Y 0.8 Yb} 0.2) the composition of the second intermediate layer 3b at a ratio of 2 _Si 2 _{O 7} is 0.65 _Y 2 _O 3 -24.3 weight a% _Yb 2 _O 3 -20.0 weight% SiO _2.

The difference between the coefficient of thermal expansion of the second intermediate layer 3b and the coefficient of thermal expansion of the first intermediate layer 3a is preferably set to 4 × 10 ⁻⁶ / K or less. Further, the difference between the coefficient of thermal expansion of the second intermediate layer 3b and the coefficient of thermal expansion of the outermost layer 2 in contact with the second intermediate layer 3b is also preferably 4 × 10 ⁻⁶ / K or less. Therefore, the thermal expansion coefficient of the second intermediate layer 3b is more preferably about 6.3 × 10 ⁻⁶ / K. Thereby, the coefficient of thermal expansion between the base material 1 (bond coat 4), the first intermediate layer 3a, the first intermediate layer 3a, the second intermediate layer 3b, and the second intermediate layer 3b and the outermost layer 2 The difference can be easily made the same, and the thermal stress can be particularly reduced. In this case, the ratio of (Y _0.8 Yb _0.2 ) ₂ Si ₂ O ₇ is 0.3, and the composition of the second intermediate layer 3b is Y ₂ O ₃ -23.6 mass% Yb ₂ O. ₃ is -22.4 wt% SiO _2.

  Returning to FIG. 1, the bond coat 4 is for supporting the first intermediate layer 3 a on the base material 1 and constitutes a part of the environment-resistant coating 10. The bond coat 4 can be formed by arbitrarily combining one or more of silicon, various silicides, mullite, BSAS (barium strontium aluminosilicate), and the like.

  The thickness of the bond coat 4 can be, for example, not less than 20 μm and not more than 200 μm.

  Further, it is preferable that the thermal expansion coefficient of the bond coat 4 is substantially equal to the thermal expansion coefficient of the substrate 1. Specifically, the difference between the coefficient of thermal expansion of the bond coat 4 and the coefficient of thermal expansion of the substrate 1 is preferably, for example, 10% or less of the coefficient of thermal expansion of the substrate 1. By doing so, the thermal stress between the bond coat 4 and the substrate 1 can be reduced.

  The total thickness of the environment-resistant coating 10 including each of the above layers is not necessarily specified because it is determined by the thickness of each of the above layers. Is 500 μm or less. By setting the thickness of the environment-resistant coating 10 in this range, there is obtained an advantage that both steam resistance and heat cycle characteristics are compatible.

  According to the environment-resistant coating 10 described above, thermal diffusion of ytterbium from the outermost layer 2 to the first intermediate layer 3a can be suppressed, and the phase stability of the outermost layer 2 can be maintained in a high state. Thereby, it is possible to provide the environment-resistant coating 10 that can maintain good environmental resistance performance for a long period of time.

  Further, the coefficient of thermal expansion gradually increases from the substrate 1 toward the outermost layer 2. That is, the thermal expansion coefficient of the second intermediate layer 3b is larger than the thermal expansion coefficients of the base material 1 and the bond coat 4, the thermal expansion coefficient of the first intermediate layer 3a is larger than the thermal expansion coefficient of the second intermediate layer 3b, The thermal expansion coefficient of the outermost layer 2 is larger than the thermal expansion coefficient of the first intermediate layer 3a. In this manner, the thermal stress generated in the environment-resistant coating 10 when the environment-resistant coating 10 is exposed to a high temperature can be reduced. Thus, even the outermost layer 2 having a thermal expansion coefficient that is significantly different from the thermal expansion coefficient of the substrate 1 because it contains YbSZ can be arranged with respect to the substrate 1. Then, for example, the outermost layer 2 can improve high steam resistance and high-temperature durability, and can improve environmental resistance.

  The environment-resistant coating 10 is applicable to, for example, environment-resistant components (not shown). That is, an environment-resistant component according to one embodiment of the present invention includes a substrate 1 containing a ceramic-based composite material as a main component, and the above-described environment-resistant coating 10 formed on the substrate 1. Is provided. Examples of the environment-resistant components include, for example, wings, split rings, and the like provided in aircraft engines, industrial gas turbines, and the like.

  According to such an environment-resistant component, thermal diffusion of ytterbium from the outermost layer 2 to the first intermediate layer 3a can be suppressed, and the phase stability of the outermost layer 2 can be maintained in a high state. Thereby, it is possible to provide an environment-resistant component capable of maintaining good environmental performance for a long time.

  FIG. 4 is a flowchart illustrating a method of manufacturing the environment-resistant coating 10 according to one embodiment of the present invention. The manufacturing method shown in FIG. 4 is based on the method of forming the outermost layer 2 and at least one intermediate layer 3 (first layer) disposed between the substrate 1 and the outermost layer 2 on the substrate 1 containing a ceramic-based composite material as a main component. This is a method for producing an environment-resistant coating 10 (see FIG. 1) including a first intermediate layer 3a and a second intermediate layer 3b).

  The environment-resistant coating 10 can be manufactured, for example, by manufacturing (forming) the bond coat 4, the second intermediate layer 3b, the first intermediate layer 3a, and the outermost layer 2 on the surface of the substrate 1 in this order. it can. Therefore, first, the bond coat 4 is formed on the substrate 1 (Step S1). Specifically, for example, the bond coat 4 can be manufactured by spraying, for example, a constituent material (for example, silicon) of the bond coat 4 on the surface of the base material 1. The production conditions (for example, time, temperature, etc.) are arbitrary, but it is preferable to determine the production conditions so that the bond coat 4 is formed densely.

Next, the second intermediate layer 3b is formed on the surface of the bond coat 4 (Step S2). Specifically, for example, the second intermediate layer 3b can be manufactured by disposing the constituent material of the second intermediate layer 3b on the surface of the bond coat 4. The constituent material of the second intermediate layer 3b is, for example, a mixed powder of (Y _0.8 Yb _0.2 ) ₂ SiO ₅ and (Y _0.8 Yb _0.2 ) ₂ Si ₂ O ₇ as described above. is there. The constituent materials can be arranged by, for example, a slurry coating method, a dip ring method, a thermal spray method, an electron beam physical vapor deposition method (EB-PVD method), or the like. The manufacturing conditions (for example, time, temperature, etc.) of the second intermediate layer 3b are arbitrary, but it is preferable to determine the manufacturing conditions so that the second intermediate layer 3b is formed densely.

Further, the first intermediate layer 3a is formed on the surface of the second intermediate layer 3b (Step S3, first intermediate layer manufacturing step). Specifically, for example, the first intermediate layer 3a can be manufactured by disposing the constituent material of the first intermediate layer 3a on the surface of the second intermediate layer 3b. As a constituent material of the first intermediate layer 3a, for example, the first intermediate layer 3a contains a rare earth compound which is at least one of rare earth stabilized zirconia and rare earth silicate, and the content of ytterbium is in the first intermediate layer. Is a material that accounts for 90 mol% or more of the entire rare earth element. More specifically, for example, it is a mixed powder of YbSZ and Yb ₂ SiO ₅ as described above.

  The arrangement of the constituent materials of the first intermediate layer 3a is, for example, a method of applying a raw material slurry (for example, a slurry containing the mixed powder) and then sintering, or a method of immersing the raw material slurry (for example, a slurry containing the mixed powder) and then sintering. EB-PVD method, a thermal spraying method, or an electron beam physical vapor deposition method. Although the manufacturing conditions (for example, time, temperature, etc.) of the first intermediate layer 3a are arbitrary, it is preferable to determine the manufacturing conditions so that the first intermediate layer 3a is formed densely.

  Finally, the outermost layer 2 is formed on the surface of the first intermediate layer 3a (Step S4, outermost layer manufacturing step). Specifically, for example, specifically, for example, by arranging the constituent material of the outermost layer 2 on the surface of the first intermediate layer 3a, the outermost layer 2 can be manufactured. The constituent material of the outermost layer 2 is made of, for example, rare earth-stabilized zirconia and contains 95% by mass or more of YbSZ as described above.

  The arrangement of the constituent materials of the outermost layer 2 is, for example, a method of applying a raw material slurry (for example, the slurry containing the above YbSZ) and then sintering, a method of immersing the raw material slurry (for example, the slurry containing the above YbSZ) and then sintering, And an electron beam physical vapor deposition method (EB-PVD method). The manufacturing conditions (for example, time, temperature, etc.) of the outermost layer 2 are arbitrary, but it is preferable to determine the manufacturing conditions so that the outermost layer 2 is formed densely.

  According to the above manufacturing method, thermal diffusion of ytterbium from the outermost layer 2 to the first intermediate layer 3a can be suppressed, and the phase stability of the outermost layer 2 can be maintained in a high state. Thereby, a method for manufacturing the environment-resistant coating 10 capable of maintaining good environmental resistance performance for a long time can be provided.

  Hereinafter, an embodiment of the present invention will be described more specifically with reference to specific examples.

<Evaluation of thermal expansion coefficient for each layer>
As a material of the outermost layer 2, ZrO ₂ -17% by mass Yb ₂ O ₃ powder was prepared, and a granulated powder having a diameter of about 50 μm was obtained by a spray drying method.

As the material of the first intermediate layer 3a, mixed powder (the composition of the YbSZ and _{Yb 2 SiO 5: Yb 2 O} 3 -34 wt% _ZrO 2 -8 _wt% SiO 2 volume ratio of .YbSZ 0.17 or 0. 72 or less), and a granulated powder having a diameter of about 50 μm was obtained by a spray drying method. Since the first intermediate layer 3a contains only Yb as a rare earth, the content of Yb in the first intermediate layer 3a is 90 mol% or more with respect to the entire rare earth in the first intermediate layer 3a (specifically, 100%). Mol%).

As a material of the second intermediate layer 3b, a mixed powder of (Y _0.8 Yb _0.2 ) ₂ SiO ₅ and (Y _0.8 Yb _0.2 ) ₂ Si ₂ O ₇ (composition: Y ₂ O ₃ − 24% by mass Yb ₂ O ₃ -22% by mass SiO ₂ (volume ratio of (Y _0.8 Yb _0.2 ) ₂ Si ₂ O ₇ is 0.1 or more and 0.65 or less) prepared by a spray drying method. A granulated powder having a diameter of about 50 μm was obtained.

Mullite (3Al ₂ O ₃ -2SiO ₂ ) was prepared as another material of the second intermediate layer 3b, and a granulated powder having a diameter of about 50 μm was obtained by a spray drying method.

  As a material for the bond coat 4, a commercially available Si sprayed powder was prepared.

  Each of the above powders was sprayed on the inert substrate 1 to form a sprayed coating (five types) having a thickness of about 2 mm, thereby forming five types of simulated layers. That is, one simulation layer is formed on each substrate 1. Then, for each of the five types of simulated layers, the coefficient of thermal expansion from room temperature (25 ° C.) to 1200 ° C. was measured. The measurement of the thermal expansion coefficient was performed in accordance with JIS R 1618: 2002. The measurement results are summarized in Table 1 below.

Table 1 also shows, as a reference, the coefficient of thermal expansion of a silicon carbide fiber reinforced silicon carbide material (SiC-SiC) simulating the base material 1. In Table 1, the “second intermediate layer 3b (mixed powder)” is a mixture of (Y _0.8 Yb _0.2 ) ₂ SiO ₅ and (Y _0.8 Yb _0.2 ) ₂ Si ₂ O _7. It is a result using powder. Further, in Table 1, "second intermediate layer 3b (mullite)" is the result of using mullite powder. The “preferred range” refers to the preferred range described in the description of each layer.

  As shown in Table 1, the thermal expansion coefficients of the outermost layer 2, the first intermediate layer 3a, the second intermediate layer 3b (each of the mixed powder and the mullite), and the bond coat 4 are all included in the preferred ranges. It was confirmed that. Further, it was confirmed that the second intermediate layer 3b (each of the mixed powder and the mullite), the first intermediate layer 3a, and the outermost layer 2 increased in thermal expansion coefficient in this order.

<Evaluation of environmental resistance performance of environmental resistant coating>
As an example, the environment-resistant coating 10 was manufactured using each of the above materials and following the flow shown in FIG. An environment-resistant coating 10 using the mixed powder as the second intermediate layer 3b and an environment-resistant coating 10 using mullite as the second intermediate layer 3b were produced. The produced environment-resistant coating 10 has a 100 μm outermost layer 2, a 100 μm first intermediate layer 3a, and a 100 μm second intermediate layer 3b in this order, and has the same structure as that shown in FIG. It is. And the 2nd intermediate | middle layer 3b and the base material 1 (thickness 3mm) made of a silicon carbide fiber reinforced silicon carbide material (SiC-SiC) were joined by the bond coat 4 of 100 micrometers.

  A thermal cycle test was performed on the two environmentally resistant coatings 10 so that the surface temperature became 1200 ° C. Specifically, the front surface is heated so that the surface temperature (the surface of the outermost layer 2) is 1200 ° C. and the back surface temperature (the surface of the base material 1) is 1000 ° C., the back surface is cooled, and the heating is stopped after 5 minutes. The cycle of cooling the entire environment-resistant coating 10 to 100 ° C. or lower was repeated 1,000 times. As a result, in any of the environment-resistant coatings 10, peeling was not visually confirmed. Therefore, it was confirmed that the environment-resistant coating 10 according to one embodiment of the present invention did not peel even when repeatedly exposed to high temperatures, and was excellent in environmental resistance performance.

  This is presumably because both the outermost layer 2 and the first intermediate layer 3a contain the same level of ytterbium. Therefore, even if the thermal cycle is repeatedly performed, it is considered that the thermal diffusion of ytterbium between the outermost layer 2 and the first intermediate layer 3a is suppressed, and good environmental resistance performance is maintained for a long time.

  Further, as Comparative Example 1, two types of environment-resistant coatings were produced in the same manner as in the above Example except that the YbSZ concentration contained in the outermost layer 2 was 90% by mass. Further, as Comparative Example 2, two types of environmentally-resistant coatings were produced in the same manner as in the above-mentioned Example, except that the first intermediate layer 3a was composed of only a rare earth silicate (not including YbSZ). Therefore, according to Comparative Examples 1 and 2, four types of environmental resistant coatings were produced.

  When a thermal cycle test was performed for each of the four types of environmentally resistant coatings produced in the same manner as in Example 1, peeling was visually confirmed after 600 to 700 cycles. Therefore, in Comparative Examples 1 and 2, it was confirmed that the environmental resistance performance was low. This is because, for Comparative Example 1, the YbSZ concentration of the rare earth stabilized zirconia contained in the outermost layer 2 was low and the phase stability was not high, and as a result, phase transformation caused by the heat cycle test occurred, and peeling occurred. Conceivable. In Comparative Example 2, since the first intermediate layer 3a did not contain YbSZ, the difference in thermal expansion coefficient between the outermost layer 2 and the second intermediate layer 3b became too large, and the thermal stress caused by the thermal cycle test was reduced. It is considered that peeling occurred at an early stage.

Reference Signs List 1 base material 2 outermost layer 3 intermediate layer 3a first intermediate layer 3b second intermediate layer 4 bond coat 10 environment resistant coating

Claims (10)

An environment-resistant coating formed on a base material including a ceramic-based composite material as a main component and including an outermost layer and at least one intermediate layer disposed between the base material and the outermost layer,
The outermost layer is composed of rare earth stabilized zirconia, and contains 95% by mass or more of ytterbia stabilized zirconia,
The first intermediate layer in contact with the outermost layer includes a rare earth compound that is at least one of rare earth stabilized zirconia and rare earth silicate,
An environment-resistant coating, wherein the content of ytterbium in the first intermediate layer is 90 mol% or more based on the entire rare earth element in the first intermediate layer. The environmental coating of claim 1, wherein the first intermediate layer comprises at least rare earth stabilized zirconia. The environment resistant coating according to claim 1, wherein a thermal expansion coefficient of the first intermediate layer is not less than 8 × 10 ⁻⁶ / K and not more than 10 × 10 ⁻⁶ / K. 4. The at least one intermediate layer includes a second intermediate layer in contact with the first intermediate layer and disposed on the side of the substrate,
The environment-resistant coating according to any one of claims 1 to 3, wherein a thermal expansion coefficient of the second intermediate layer is smaller than a thermal expansion coefficient of the first intermediate layer. The environment-resistant coating according to claim 4, wherein the second intermediate layer has a coefficient of thermal expansion of 5 ^10-6 / K or more and 7 ^10-6 / K or less. The second intermediate layer includes ytterbia silicate and yttria silicate,
The environment resistant coating according to claim 4, wherein a concentration of yttrium in the second intermediate layer is higher than a concentration of yttrium in the first intermediate layer. The environment-resistant coating according to any one of claims 1 to 6, wherein the first intermediate layer contains the rare earth compound in an amount of 95% by mass or more. The ceramic-based composite material includes at least one of a silicon carbide fiber reinforced silicon carbide material (SiC-SiC) and a carbon fiber reinforced silicon carbide material (C-SiC). An environment-resistant coating according to any one of the preceding claims. A base material containing a ceramic-based composite material as a main component,
An environment-resistant component, comprising: the environment-resistant coating according to claim 1, wherein the environment-resistant coating is formed on the substrate. What is claimed is: 1. A method for producing an environment-resistant coating comprising a top surface layer, and at least one intermediate layer disposed between the base material and the top surface layer, on a base material containing a ceramic-based composite material as a main component, ,
A first intermediate layer that is in contact with the outermost layer and includes a rare earth compound that is at least one of rare earth stabilized zirconia or a rare earth silicate, and the content of ytterbium is reduced with respect to the entire rare earth element in the first intermediate layer. A first intermediate layer manufacturing step of manufacturing the first intermediate layer that is 90 mol% or more;
A method for producing an outermost surface layer made of rare earth-stabilized zirconia and comprising the outermost layer containing 95% by mass or more of ytterbia-stabilized zirconia.

Images