JP2001279473A - Ceramic thermal barrier coating - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To alleviate thermal stress caused by a temperature gradient inside a film to prevent peeling or damage of a coating, and to improve film characteristics (lifetime and thermal shock resistance). SOLUTION: A first layer covering a metal base material 10 is a metal bonding layer 12 made of any one of a Ni-based alloy, a Co-based alloy, a Ni-Co-based alloy and a Co-Ni-based alloy.
The second layer covering the layer is a ceramic heat-shielding layer 14 made of ceramics having low thermal conductivity, and the third layer covering this second layer is made of ceramic having a smaller coefficient of thermal expansion than the ceramic constituting the second layer. The outermost ceramic layer 18 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic thermal barrier coating for protecting a metal member such as a moving and stationary blade (a moving blade and a stationary blade) of a gas turbine and a combustor from a high temperature environment caused by a combustion gas. .

[0002]

2. Description of the Related Art A thermal barrier coating (thermal barrier) for protecting metal members such as moving and stationary blades and a combustor of a gas turbine from a high temperature environment caused by a combustion gas.
Coating (TBC) is a metal bonding layer (MCrAlY: M = 100 μm) of about 100 μm applied on a metal substrate.
Ni and / or Co), and a two-layer structure composed of a ceramic heat shield layer of about 200 microns made of a low thermal conductive ceramic represented by stabilized zirconia applied to a surface exposed to a combustion gas is generally used. It is. As shown in FIG. 5, the thermal barrier coating having the two-layer structure is obtained by applying a metal bonding layer 12 (first layer) and a ceramic thermal barrier layer 14 (second layer) on a metal substrate 10. Usually, the metal bonding layer is applied by low pressure spraying (such as low pressure plasma spraying).
The ceramic thermal barrier is applied by atmospheric plasma spraying.

As shown in FIG. 7, the metal member coated with the above-mentioned heat-shielding coating has a heat-shielding effect, but the backside exposed to the combustion gas is cooled. A temperature gradient occurs in the thickness direction inside the thermal layer, and the thermal stress accompanying the thermal gradient induces damage to the film itself. In the above-described two-layer thermal barrier coating, a graded-structure coating in which the composition is changed from the metal bonding layer to the ceramic thermal barrier layer has been proposed for the purpose of relaxing thermal stress inside the ceramic layer. . As shown in FIG. 6, the thermal barrier coating is obtained by applying a metal bonding layer 12 (first layer) and a metal / ceramic gradient composition layer 16 (second layer) on a metal substrate 10.

In the above-described thermal barrier coating having a two-layer structure, a technique is known in which a hard ceramic layer is further provided on a ceramic thermal barrier layer to form a three-layer structure, thereby improving the wear resistance of the coating. ing. Further, a technique is known in which a ceramic layer for preventing the penetration of corrosion components containing oxygen is further provided on the ceramic heat-insulating layer to improve the life of the coating. For example, JP-A-6-88197 discloses a technique for providing a dense ceramic layer on a ceramic heat-shielding layer. Japanese Patent No. 2575286 discloses a heat shielding material in which a layer in contact with a metal substrate is a metal layer, an outermost layer is a composite ceramic layer, and a gradient composition layer of metal and ceramic is provided between the metal layer and the composite ceramic layer. It has been disclosed.

[0005]

The thermal stress caused by the temperature gradient inside the ceramic thermal barrier layer is one of the factors that cause damage to the coating. In order to alleviate this thermal stress, the composition gradient coating in which the composition from the metal bonding layer to the ceramic heat shield layer is continuously changed exhibits more excellent thermal shock characteristics due to its characteristics. However, in a gradient layer in which a ceramic and a metal are mixed, there is a problem that metal particles dispersed in the mixed gradient layer are easily oxidized, causing damage to the coating. In addition, the technique of improving the coating properties by adding a third layer to the ceramic heat shield layer is intended to improve abrasion resistance, prevent corrosion of oxygen or the like, or prevent penetration of oxidizing components,
Damage due to thermal stress inside the coating is not considered.

The present invention has been made in view of the above points, and an object of the present invention is to provide a metal bonding layer (first
Layer), a ceramic thermal barrier layer (second layer), and a thermal barrier coating having a three-layer structure including a topmost ceramic layer (third layer) composed of ceramics having a lower thermal expansion than the ceramics constituting the thermal barrier layer. The present invention provides a ceramic thermal barrier coating capable of relieving thermal stress caused by a temperature gradient inside a film that causes peeling or damage of the coating, thereby improving film characteristics (life and thermal shock resistance). It is in. Further, an object of the present invention is to provide, in the above-mentioned thermal barrier coating, a mixed layer of a ceramic constituting the second layer and a ceramic constituting the third layer or a gradient composition layer between the second layer and the third layer. It is another object of the present invention to provide a ceramic thermal barrier coating that can further reduce the internal thermal stress of the film and improve the film characteristics (lifetime and thermal shock resistance) by providing the ceramic thermal barrier coating.

[0007]

In order to achieve the above object, the present invention provides a ceramic thermal barrier coating, wherein the first layer covering the metal substrate is made of a Ni-based alloy, a Co-based alloy, or a Ni-based alloy.
A metal bonding layer made of any one of a -Co-based alloy and a Co-Ni-based alloy, and a second layer covering the first layer is a ceramic heat-shielding layer made of ceramics having low thermal conductivity; Is configured to be the outermost ceramic layer made of ceramics having a smaller coefficient of thermal expansion than the ceramics forming the second layer (see FIG. 1). In the ceramic thermal barrier coating of the present invention described above, it is preferable to provide a ceramic mixed layer in which the ceramic constituting the second layer and the ceramic constituting the third layer are mixed between the second layer and the third layer. (See FIG. 2). In the above-mentioned ceramic thermal barrier coating of the present invention, the second layer is provided between the second layer and the third layer.
The mixing ratio of the ceramics forming the second layer increases toward the surface in contact with the layer, and the mixing ratio of the ceramics forming the third layer increases toward the surface in contact with the third layer. It is preferable to provide a ceramic gradient composition layer in which the mixing ratio of the ceramic constituting the layer and the ceramic constituting the third layer is changed substantially continuously (see FIG. 3).

In these ceramic thermal barrier coatings of the present invention, the thickness of the first metal bonding layer is 50
It is preferable that the thickness be in the range of 200 μm to 200 μm. It is to be noted that a more preferable thickness of the metal bonding layer has a lower limit of 75 μm and an upper limit of 150 μm. When the thickness of the metal bonding layer is less than the lower limit, the effect of suppressing permeation of oxidizing or corrosive components such as oxygen becomes small, while when the thickness of the metal bonding layer exceeds the upper limit, the cooling efficiency of the metal member is reduced. Decrease. In the ceramic thermal barrier coating of the present invention, the thickness of the ceramic thermal barrier layer as the second layer is 10
The thickness is preferably in the range of 0 to 500 μm. It is to be noted that a more preferable thickness of the ceramic heat shielding layer is such that the lower limit is 20.
0 μm, and the upper limit is 300 μm. If the thickness of the ceramic heat-insulating layer is less than the lower limit, the heat-shielding effect is not sufficient, while if the thickness of the ceramic heat-insulating layer exceeds the upper limit, the thermal stress increases and peeling or damage occurs. It will be easier. In the ceramic thermal barrier coating of the present invention, the ratio of the thickness of the ceramic thermal barrier layer as the second layer to the thickness of the outermost ceramic layer as the third layer is determined by the thickness of the metal member to which the thermal barrier coating is applied. It is preferable to adjust the coefficient of thermal expansion in accordance with the temperature gradient inside the film based on the temperature conditions to which the film is exposed, so as to make the ratio such that the internal stress of the film can be reduced. For example, when the thickness of the ceramic thermal barrier layer as the second layer is in the range of 100 to 500 μm, the thickness of the outermost ceramic layer as the third layer is determined by the metal member to which the coating of the present invention is applied. Depending on the ambient temperature conditions to be exposed (for example, 1200 to 1300 ° C.)
It can be in the range of 100 μm, preferably in the range of 20 to 50 μm.

In these ceramic thermal barrier coatings of the present invention, the ceramic constituting the second layer may be MgO, CaO, Y ₂ O ₃ , Yb ₂ O ₃ as a stabilizer.
It is preferable to use stabilized zirconia or partially stabilized zirconia using any one of CeO and CeO. In the ceramic thermal barrier coating of the present invention, the ceramic constituting the third layer is preferably alumina, chromia, mullite, cordierite, or the like.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications. FIG. 1 is a conceptual diagram showing a ceramic thermal barrier coating according to a first embodiment of the present invention. In the present embodiment, a metal bonding layer (metal bond layer) 12 is formed on a surface of a metal substrate 10 as a first layer, and stabilized zirconia or partially stabilized zirconia is formed as a second layer formed after the first layer. This is a thermal barrier coating system in which a ceramic thermal barrier layer 14 and an outermost ceramic layer 18 made of ceramic having a lower coefficient of thermal expansion than the ceramic constituting the second layer as the third layer on the outermost surface.

A metal bonding layer (metal bonding layer) as a first layer
12, MCrAlY (M = Ni and / or C
o) is generally used, and its thickness is 50-200 μm.
m, desirably 75 to 150 μm. Metal bonding layer 12
Are, for example, thermal spraying such as reduced pressure plasma spraying, chemical vapor deposition (C
VD) or physical vapor deposition (PVD). For the ceramic heat shield layer 14 as the second layer, stabilized zirconia or partially stabilized zirconia is usually used as ceramics.
It is preferable to use stabilized zirconia or partially stabilized zirconia using any of O, CaO, Y ₂ O ₃ , Yb ₂ O ₃ and CeO. The ceramic thermal barrier layer 14 is formed, for example, by thermal spraying such as atmospheric plasma spraying, or chemical vapor deposition (CVD).
Or, by physical vapor deposition (PVD) or the like, a thickness of 100 to 500 μm
m, preferably 200 to 300 μm. In addition,
The ceramic heat shield layer can be a mixed layer of metal and ceramic or a graded composition layer.

Further, the outermost surface ceramic layer as the third layer
Reference numeral 18 denotes zirconia (10.5 × 10
^-6/ K) composed of ceramics with a lower coefficient of thermal expansion than
It is used as ceramics to form the third layer.
Oxides are desirable in view of the usage environment.
Mina (8 × 10^-6/ K), chromia (8.7 × 10^-6 /
K), mullite (4.5 × 10^-6/ K), Cordierai
(2.0 × 10^-6/ K) and the like. Top surface sera
The mixed layer 18 is formed, for example, by spraying such as atmospheric plasma spraying.
By chemical vapor deposition (CVD) or physical vapor deposition (PVD)
Will be constructed. Also, the ceramic heat shield layer 1 as the second layer
4 and the thickness of the third ceramic layer 18 as the third layer.
The ratio is that the metal parts to which the coating of the invention is applied are exposed
Temperature conditions. That is, the temperature inside the film
Adjust the coefficient of thermal expansion according to the gradient to reduce the internal stress of the film
So that For example, the thickness of the ceramic heat insulating layer 14
Is 100 to 500 μm, the outermost ceramic
The thickness of the metal layer 18 depends on the thickness of the gold to which the coating of the present invention is applied.
Atmospheric temperature conditions to which the metal member is exposed (for example, 120
0 to 1300 ° C.), preferably 5 to 100 μm
Can be 20 to 50 μm.

FIG. 2 is a conceptual diagram showing a ceramic thermal barrier coating according to a second embodiment of the present invention. In the present embodiment, a metal bonding layer (metal bond layer) 12 as a first layer, a ceramic heat-insulating layer 14 as a second layer to be constructed after the first layer, and a An outermost ceramic layer 18 made of a ceramic having a lower coefficient of thermal expansion than the ceramic constituting the second layer is provided, and further, a stabilized zirconia or a partially stabilized This is a thermal barrier coating system provided with a ceramic mixed layer 20 in which zirconia fluoride and a ceramic having a smaller coefficient of thermal expansion than zirconia are mixed. By forming a mixed layer between the second layer and the outermost surface layer, the thermal stress relaxation characteristics can be further improved. The ceramic mixed layer 20 is applied to a thickness of 10 to 50 μm, preferably 20 to 40 μm by, for example, thermal spraying such as atmospheric plasma spraying, chemical vapor deposition (CVD), or physical vapor deposition (PVD). Other configurations and operations are the same as those in the first embodiment.

FIG. 3 is a conceptual diagram showing a ceramic thermal barrier coating according to a third embodiment of the present invention. In the present embodiment, a metal bonding layer (metal bond layer) 12 as a first layer, a ceramic heat-insulating layer 14 as a second layer to be constructed after the first layer, and a An outermost ceramic layer 18 made of a ceramic having a lower coefficient of thermal expansion than the ceramic constituting the second layer is provided, and further, a stabilized zirconia or a partially stabilized This is a thermal barrier coating system provided with a ceramic gradient composition layer 22 in which the mixing ratio of zirconia fluoride and ceramics having a smaller coefficient of thermal expansion than zirconia is changed.

In the ceramic graded composition layer 22, the mixing ratio of the ceramics (stabilized zirconia or partially stabilized zirconia) forming the ceramic heat shield layer 14 increases toward the surface in contact with the ceramic heat shield layer 14, and The mixture ratio of the ceramics (ceramics having a smaller coefficient of thermal expansion than zirconia) constituting the outermost ceramic layer 18 is changed substantially continuously so that the mixture ratio of the ceramics constituting the outermost ceramic layer 18 increases toward the surface in contact with the surface ceramic layer 18. ing. By forming the two gradient composition layers between the second layer and the outermost layer, the thermal stress relaxation characteristics can be further improved. As a method of applying the ceramic gradient composition layer 22, the composition ratio of both ceramic powders is set to, for example, 10 vo.
A method in which a mixed powder changed every l% is prepared by a ball mill or the like and sequentially laminated by atmospheric plasma spraying, or the supply ratio of both is continuously changed from a spraying apparatus having two kinds of powder supply ports. The thickness is 10 to 150 μm, preferably 50 to 100 μm
It is. Other configurations and operations are the same as those in the first embodiment.

When the ceramic thermal barrier coating of the present invention is applied to a metal member used in a high-temperature environment such as a gas turbine component, the thermal barrier coating applied to the turbine component and the like is taken into consideration in consideration of construction costs. It is not necessary to apply the present invention to the entire thermal coating. In particular, the thermal barrier coating of the present invention is applied only to a portion where the use condition is severe (for example, a leading edge portion of a turbine blade), and the other portions correspond to the conventional coating. It is also possible.

[0017]

EXAMPLES Examples and comparative examples are shown below to show the features of the present invention.
Clarify the sign. First Embodiment Referring to FIG. 1, the first embodiment is used for a gas turbine blade.
Vacuum rod as the first layer on a round bar base made of a superalloy
100μm NiCoCrAlY alloy applied by Zuma spraying
After that, as a second layer thereon, Y is added as a stabilizer._TwoO_ThreeFor
Of stabilized zirconia by atmospheric plasma spraying
μm, and alumina as the third layer
50 μm was applied by atmospheric plasma spraying. Example 2 Referring to FIG. 2, in Example 1, the second layer
Some Y_TwoO_ThreeAfter applying stabilized zirconia, Y_TwoO_ThreeStable
Plasma spraying of a mixed layer of zirconia and alumina
80 μm, and alumina on it
did. That is, the second layer and the third layer in Example 1
In between, a mixed layer of both was constructed. Y_TwoO_Three Stabilized zirconi
The mixing ratio of alumina and alumina was 1: 1.

Comparative Example 1 Referring to FIG. 5, a NiCoCrAlY alloy was applied as a first layer by vacuum plasma spraying to a thickness of 100 μm on a round bar base made of a superalloy used for gas turbine blades. As a second layer, stabilized zirconia using Y ₂ O ₃ as a stabilizer is sprayed by atmospheric plasma spraying for 250 minutes.
μm construction.

A thermal cycle test was performed on these three types of samples, and their thermal shock characteristics were evaluated. In the heat cycle test, after heating at 1000 ° C. for 15 minutes,
The step of cooling for 5 minutes was performed as one cycle. As a result, as shown in FIG.
While cracks occurred in the ceramic layer at about 600 cycles, the samples of Example 1 and Example 2
No cracks etc. occur in the ceramic layer even at 0 cycles or more,
It showed high durability.

[0020]

As described above, the present invention has the following effects. (1) In the ceramic thermal barrier coating, the outermost ceramic layer having a lower coefficient of thermal expansion than the ceramic constituting the thermal barrier layer is provided on the outermost surface of the ceramic thermal barrier layer on the heating side, so that the coating can be peeled off. Relieves thermal stress caused by temperature gradient inside the film that causes damage, and characteristics of film (life and thermal shock resistance)
Can be improved. (2) In the above-mentioned thermal barrier coating, when a mixed layer of ceramics constituting the second layer and ceramics constituting the third layer or a gradient composition layer is provided between the second layer and the third layer. In addition, the thermal stress inside the film can be alleviated to improve the film characteristics (lifetime and thermal shock resistance). (3) When the ceramic thermal barrier coating of the present invention is applied to metal members such as moving and stationary blades (moving blades and stationary blades) of gas turbines and combustors, the performance of these members can be improved (longer life, higher thermal performance). (Improvement of impact characteristics).

[Brief description of the drawings]

FIG. 1 is a conceptual sectional view of a ceramic thermal barrier coating according to a first embodiment of the present invention.

FIG. 2 is a conceptual sectional view of a ceramic thermal barrier coating according to a second embodiment of the present invention.

FIG. 3 is a conceptual sectional view of a ceramic thermal barrier coating according to a third embodiment of the present invention.

FIG. 4 is a graph showing the results of a heat cycle test of Examples and Comparative Examples.

FIG. 5 is a conceptual sectional view of an example of a conventional ceramic thermal barrier coating.

FIG. 6 is a conceptual sectional view of another example of the conventional ceramic thermal barrier coating.

FIG. 7 is a conceptual diagram illustrating the operation and effect when a ceramic thermal barrier coating is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Metal base material 12 Metal bonding layer 14 Ceramic heat shielding layer 16 Metal / ceramic gradient composition layer 18 Top surface ceramic layer 20 Ceramic mixed layer 22 Ceramic gradient composition layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Haruki Hino 1-1, Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries, Ltd. Inside Akashi Plant (72) Inventor Hyoe Ramino 1-1, Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries F-term (reference) in Akashi Factory Co., Ltd.

Claims (9)

[Claims] A first layer covering a metal substrate is a metal bonding layer made of any one of a Ni-based alloy, a Co-based alloy, a Ni-Co-based alloy, and a Co-Ni-based alloy. The second layer to be coated is a ceramic heat-shielding layer made of ceramics having low thermal conductivity, and the third layer covering this second layer is the outermost surface made of ceramics having a smaller coefficient of thermal expansion than the ceramics constituting the second layer. Ceramic thermal barrier coating characterized by being a ceramic layer. 2. A ceramic heat shield according to claim 1, wherein a ceramic mixed layer obtained by mixing ceramic constituting the second layer and ceramic constituting the third layer is provided between the second layer and the third layer. coating. 3. The mixing ratio of ceramics constituting the second layer between the second layer and the third layer increases toward the surface in contact with the second layer and increases toward the surface in contact with the third layer. In order to increase the mixing ratio of the ceramic constituting the third layer, a ceramic gradient composition layer in which the mixing ratio of the ceramic constituting the second layer and the ceramic constituting the third layer is changed substantially continuously is provided. The ceramic thermal barrier coating according to claim 1. 4. The thickness of the first metal bonding layer is 50 to 50.
4. The ceramic thermal barrier coating according to claim 1, wherein the thickness is in the range of 200 [mu] m. 5. The ceramic thermal barrier coating according to claim 1, wherein the thickness of the ceramic thermal barrier layer as the second layer is in the range of 100 to 500 μm. 6. A ceramic heat shield layer as a second layer and a third
The ratio of the thickness to the outermost ceramic layer, which is the layer, is determined by adjusting the coefficient of thermal expansion according to the temperature gradient inside the film based on the temperature conditions to which the metal member to which the thermal barrier coating is applied is exposed. The ratio is such that the stress can be reduced.
5. The ceramic thermal barrier coating according to any one of the above items 5. 7. The ceramic thermal barrier layer as the second layer has a thickness of 100 to 500 μm, and the third ceramic layer as the outermost layer has a thickness of 5 to 100 μm. Ceramic thermal barrier coating. 8. The ceramic constituting the second layer is made of MgO, CaO, Y ₂ O ₃ , Yb ₂ O ₃ and Ce as stabilizers.
The ceramic thermal barrier coating according to any one of claims 1 to 7, which is stabilized zirconia or partially stabilized zirconia using any one of O. 9. The ceramic thermal barrier coating according to claim 1, wherein the ceramic constituting the third layer is at least one of alumina, chromia, mullite and cordierite.