JPH09316622A - Gas turbine member and its thermal insulation coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a gas turbine member to boundary peeling or the like caused by high temp. oxidation by simultaneously constructing optimum thermal spraying conditions and thermal spraying material and forming a more dense thermal insulation coating layer increased in adhesive strength. SOLUTION: This gas turbine member is provided with a metallic substrate 1, and the surface of this metallic substrate 1 is applied with a thermal insulation coating layer 2 composed of an MCrAlY base bond coat 3 and a ZrO2 -Y2 O3 base top coat 4. The bond coat 3 has characteristics of <=2% porosity smaller than that of the top coat 4 and >=100MPa adhesive strength to the metallic substrate 1. The bond coat 3 is integrally formed at 0.02 to 0.20mm coating thickness on the metallic substrate 1 using an MCrAlY base material having 20 to 50μm powdery grain diameter using a high velocity gas flame thermal spraying method with 450 to 900m/s thermal spraying velocity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine member such as a moving blade, a stationary blade, a combustor of a jet engine or a gas turbine for power generation, and a thermal barrier coating method therefor,
In particular, it relates to devising conditions such as bond spraying and top coat spraying conditions and spraying materials.

[0002]

2. Description of the Related Art In general, a jet engine or a gas turbine for power generation has a structure in which compressed air from a compressor is combusted with jet fuel or LNG and the combustion gas is converted into a rotational energy as a working medium. A gas turbine member that can be used in a high temperature environment of 1000 ° C. or higher, such as a moving blade, a stationary blade, a combustor, etc., such as Ni
It is made of a base or Co base superalloy.

In such a gas turbine member, in addition to a structure for preventing a temperature rise with respect to cooling air, a protective film (sprayed film) formed by a thermal barrier coating is formed on the outer surface thereof. This protective film usually has a two-layer film structure of a bond coat and a top coat, and is formed by using the atmospheric pressure plasma radiation method.

[0004]

However, in the protective film formed on the gas turbine member described above,
Due to the atmospheric pressure plasma spraying method, it may be difficult to exert its heat shielding property for a long time.

For example, since the thermal barrier coating is carried out by the atmospheric pressure plasma spraying method, the porosity of the protective film is as high as 10% or more, the laminated adhesion strength of the film itself is weak, especially through the pores in the film. There is a problem in terms of durability such that oxidation progresses, peeling occurs at the interface between the base material (base material) such as a moving blade, a stationary blade, and a combustor and the thermal spray coating, and the thermal spray coating is likely to fall off.

As a method for solving such a problem,
Although it is conceivable to change the constituent materials, since these constituent materials are the most advanced materials to be used at high temperature, practically it is difficult to improve only by changing the material. Further, in the thermal barrier coating, it does not make much sense to use the conventional thermal spraying method as it is and change only the thermal spraying material.

The present invention has been made in order to solve the above-mentioned conventional problems. The optimum thermal spraying conditions and thermal spraying materials are constructed at the same time to form a thermal barrier coating layer having higher density and higher adhesion strength. It is intended to improve durability against interfacial peeling and the like accompanying high temperature oxidation.

[0008]

In order to achieve the above object, the inventor of the present invention has conducted extensive studies on a thermal spray rate and a thermal spray material capable of achieving a desired porosity and adhesion strength. In general, as shown in FIG. 1, it is known that the porosity decreases and the adhesive strength (adhesion strength) increases as the spraying speed increases. For example, in the case of the conventional atmospheric pressure plasma spraying method, the maximum spraying speed was 300 to 350 m / s, and the porosity in the sprayed coating formed under these conditions was about 15%.

Based on this point, the present inventor considered that the desired porosity was 5% or less, preferably 2% or less, and as a result of various experiments, as a result, the spraying rate for achieving this porosity was 450 to 900 m. We have found that / s is optimal. That is, 450 m / s or more is required to reduce the porosity to 5% or less, and when it exceeds 900 m / s, the porosity is 0.2
This is because it is 5% or less, but the compressive residual stress on the surface of the substrate is so strong that a good film cannot be formed.

Therefore, the present inventor has conducted extensive research as a method capable of realizing a thermal spraying rate exceeding the limitation of the conventional thermal spraying method, and as a result, a high-speed gas flame thermal spraying method and a thermal spraying method using hydrogen fuel have been obtained. In addition to paying attention, various experiments were further conducted on optimum spray materials (composition, powder particle size, etc.) when using these spray methods, and as a result, the present invention was completed with the following findings.

That is, the greatest feature of the present invention is that it comprises a metal base material for gas turbine parts and a thermal barrier coating layer on the metal base material, and the thermal barrier coating layer is composed of a bond coat and a top coat. In the above gas turbine member, the bond coat has a composition of MCrAlY system and has a porosity smaller than that of the top coat.

In a second aspect of the present invention, the bond coat contains Cr in an amount of 11.00 or more and 32.00 or less, Al in an amount of 5.00 or more and 14.00 or less, and Y in an amount of 0.
20 or more and 1.90 or less, O ₂ is 1.00 or less, and Ni is the balance or Co is 17.00 or more and 38.
It is set to 00 or less, and has an MCrAlY-based composition containing inevitable impurities. In this composition, the composition range (% by weight) was set for each element for the following reasons, while focusing on improving the oxidation resistance while taking advantage of the above-mentioned spray rate.

"Cr" is an essential element for improving the oxidation resistance. If it is less than 11%, it has almost no effect in, for example, the gas turbine environment, and if it exceeds 32%, it becomes an excessive quality. It was set in the range of "0.00% or more to 32.00% or less".

"Al" has the property of diffusing into a metal base material and improving the oxidation resistance like Cr. However, if it is less than 5%, the diffusion amount is small, and if it exceeds 14%, oxygen in the atmosphere is increased. In order to reduce the film strength and the oxidation resistance by binding with Al ₂ O ₃ and conversely, the range is set to “5.00% or more and 14.00% or less”.

If "Y" is less than 0.20%, Y ₂
Do not form a stable oxide as O _3, since that would detract from the linear expansion coefficient between the formation of the oxide of unnecessarily exceeds 1.90 percent base, "0.20% or more to 1 ．
90% or less ". “O ₂ ” is an amount showing the amount of oxides, and if this quantitative value exceeds 1.00%, the film becomes brittle, so it was set in the range of “1.00% or less”.

If "Co" is less than 17.00%, there is a problem in oxidation resistance, and if it exceeds 38.00%, it becomes an excess quality, so "17.00% to 38.00%". Set to the range of.

In the invention according to claim 3, the bond coat has a porosity of 2% or less. The bond coat having this porosity can suppress base material oxidation at the interface between the thermal spray coating and the base material.

In the invention of claim 4, the bond coat has an adhesion strength of 100 MPa or more with respect to the metal substrate.

In a fifth aspect of the invention, the top coat has a ZrO ₂ --Y ₂ O ₃ system composition and a porosity of 5% or less.

In the invention according to claim 6, the bond coat has a thickness of 0.02 mm to 0.20 mm, and the top coat has a thickness of 0.10 mm to 0.50 mm. .

According to a seventh aspect of the present invention, there is provided a thermal barrier coating method for a gas turbine member, wherein a thermal spraying rate is 450 m / s.
It is characterized in that the bond coat of the thermal barrier coating layer is integrally formed on the metal base material for the gas turbine component by using the thermal spraying method of not less than 900 m / s and not more than 900 m / s.

In the invention according to claim 8, as a thermal spraying material for the bond coat, Cr is 11.00 or more and 32.00 or less and Al is 5.00 or more and 14.00 in weight%.
Hereinafter, Y is 0.20 or more and 1.90 or less, and O ₂
Of 1.00 or less, the balance of Ni or Co of 17.00
The MCrAlY-based material having a composition containing inevitable impurities is used.

In a ninth aspect of the present invention, as the thermal spray material for the bond coat, an MCrAlY-based material having a powder particle size of 20 μm or more and 50 μm or less is used.
The "powder particle size" is a normal distribution curve with a peak value of 25 to 40 m, a maximum particle size of 50 m, and a minimum particle size of 20 m.
It was set in the range of “20 μm or more and 50 μm or less” where m This is because if it exceeds 50 μm, the proportion of the unmelted particles remaining in the thermal spray coating increases, and if it is less than 20 μm, it is melted and vaporized during the thermal spraying and the coating is not formed.

In a tenth aspect of the invention, a high-speed gas flame spraying method is used as the thermal spraying method, and in the eleventh aspect of the invention, a thermal spraying method using hydrogen fuel is used as the thermal spraying method. As the "high-speed gas flame spraying method", for example, a diamond jet method in which a mixed gas of propylene and hydrogen is used as a fuel and a film is formed on the surface of a workpiece by a supersonic spraying apparatus is desirable.

According to a twelfth aspect of the present invention, in a thermal barrier coating method for a gas turbine member, a bond coat of a thermal barrier coating layer is integrally formed on a metal base material for a gas turbine component, and then a thermal spraying speed is set to 350 m. / S or more to 9
It is characterized in that the top coat of the thermal barrier coating layer is integrally formed on the bond coat by using a thermal spraying method at a speed of 00 m / s or less.

In the thirteenth aspect of the present invention, as the thermal spray material for the top coat, a ZrO ₂ —Y ₂ O ₃ based material having a powder particle size of 5 μm to 75 μm is used.

According to a fourteenth aspect of the present invention, there is provided a thermal barrier coating method for a gas turbine member, wherein the thermal spraying rate is 450 m /
Using the thermal spraying method of s or more and 900 m / s or less,
The bond coat of the thermal barrier coating layer is integrally formed on the metal base material for the gas turbine member, and then the thermal spray rate is set to 3
A top coat of the thermal barrier coating layer is integrally formed on the bond coat by using a thermal spraying method of 50 m / s or more and 900 m / s or less.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG.

FIG. 2 illustrates a schematic sectional structure of the gas turbine member according to the present invention. The gas turbine member shown in FIG. 2 is obtained by coating a thermal barrier coating layer 2 on a metal base material 1 for a gas turbine component, which is made of a super heat resistant alloy such as Ni base or Co base. The thermal barrier coating layer 2 includes the MCrAlY-based bond coat 3 and ZrO ₂ −.
It is formed of a Y ₂ O ₃ -based top coat 4.

The bond coat 3 is the above-mentioned MCrAlY.
-Based thermal spraying material, metal using a high-speed gas flame spraying method (hereinafter referred to as "HVOF") such as a diamond jet method under the conditions of powder particle size (20 to 50 μm) and spraying speed (450 to 900 m / s) 0.02 to 0.20 mm on the base material 1
Since it is integrally formed with the film thickness of 2), a porosity of 2% or less and an adhesion strength of 100 MPa or more are achieved.

The top coat 4 is made of ZrO ₂ --Y described above.
A coating thickness of 0.10 to 0.50 mm on the bond coat 3 using HVOF under the conditions of ₂ O ₃ based thermal spraying material, powder particle size (5 to 75 μm) and thermal spraying speed (350 to 900 m / s). Since it is integrally formed with, the porosity of 5% or less is achieved. Regarding the porosity, the bond coat 3 is smaller than the top coat 4.

In this embodiment, HV is used as the thermal spraying method.
Although OF is used, the present invention is not limited to this, and a thermal spraying method using hydrogen fuel may be used. The top coat is not necessarily limited to these thermal spraying methods, and a conventional atmospheric pressure plasma thermal spraying method may be used.

[0033]

Embodiments of the present invention will now be described with reference to the tables and the drawings. In this example, a Ni-base super heat-resistant alloy is used as a metal base material for a gas turbine component, and a film formation state (porosity, adhesion strength) of a thermal barrier coating layer (bond coat, top coat) on the metal base material is used. ), Oxidation resistance and peeling properties were investigated.

(Example 1) In Example 1, the state of film formation of the gas turbine member according to the present invention was examined. First,
The coating formation conditions when the thermal spraying material (MCrAlY-based bond coat material) is changed under the same thermal spraying conditions will be described based on Tables 1 to 3.

Table 1 shows the construction conditions (spraying conditions) of the spraying test using HVOF, and Table 2 shows the compositions of the three types of spraying materials (powder A, B, C) to be tested and their average powder particle diameters. To
Table 3 explains the test results of the porosity (%) of the film using the porosity measuring method by a predetermined optical micrograph.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

As a result, even under the same thermal spraying conditions, the porosity of the coating differs depending on the conditions of the thermal spraying material, mainly the difference in the average particle size, and in particular, the porosity of powder C is the smallest (spraying distance). Was less than 2% at 180 mm), and in the case of powder B, the average particle size deviated from 20 to 50 mm of the present invention and was as large as 75 mm, so it was confirmed that almost no film was formed.

Next, the state of film formation when the spraying conditions (spraying speed) are changed with the same spraying material are shown in Table 4, FIG. 3 and FIG.
It will be described based on. As the thermal spraying material, the powder C for which the best film formation was obtained was used, and the thermal spraying rate was, for comparison, the thermal spraying method (500, 750,
900 m / s) and the conventional atmospheric pressure plasma spraying method (30
0, 400 m / s) was used. The spraying distance was set to 180 mm, which achieved a porosity of 2% or less with the powder C.

Table 4 shows the test results of the porosity (%) of the coating film using the same measurement method as above and the adhesion strength (MPa) using the predetermined adhesion strength test method. FIG. 4 is an optical micrograph showing a cross-sectional grain structure of the test piece. Of these, FIG. 3 shows a test piece of the present invention (in the case of a spraying speed of 750 m / s in Table 4), and FIG. 4 shows a test piece of a comparative example (in the case of a spraying speed of 300 m / s in Table 4). To explain.

[0042]

[Table 4]

As a result of the above, even if the same thermal spray material is used,
It was confirmed that the porosity of the coating was remarkably improved due to the difference in the spraying rate, and the adhesion strength was more than double that of the conventional example. (Example 2) In Example 2, oxidation resistance and The peeling characteristics were examined. As the test method, a predetermined thermal cycle test method was used in which the test object was repeatedly heated at room temperature to 900 ° C. to examine the oxidation resistance and the peeling property.

Table 5 explains the test results of this oxidation resistance and peeling property. As a test object, a bond coat of the above-mentioned powder C of MCrAlY system was sprayed on a metal base material under the condition of a thickness of 0.15 mm by the thermal spraying method using the HVOF of the above-mentioned Example 1, and the predetermined on the bond coat. Of the ZrO ₂ —Y ₂ O ₃ composition having a mean particle diameter of 70 mm and a top coat (porosity: 3.5%) sprayed onto the thermal barrier coating test piece of the present invention; The test piece of Comparative Example prepared by the atmospheric pressure plasma spraying method of No. 2 was used.

[0045]

[Table 5]

As a result, as shown in Table 5, it was confirmed that the test piece of the present invention was more excellent in oxidation resistance and peeling resistance than the conventional one.

[0047]

As described above, according to the present invention, it is essential to form an MCrAlY-based bond coat having a porosity smaller than that of the top coat as the thermal barrier coating layer, and especially the thermal spray rate is 450. ~ 900
m / s spraying method (for example, a high-speed gas flame spraying method or a spraying method using hydrogen fuel) is used, and the powder particle size is 20 to
Since the thermal spray coating was formed under the condition of 50 μm, it is possible to construct the optimal thermal spray conditions and thermal spray material, and it is possible to form a thermal barrier coating layer with higher density and higher adhesion strength than the conventional one, resulting in high temperature oxidation. The durability against the interfacial peeling, etc. was improved.

[Brief description of drawings]

FIG. 1 is a schematic characteristic diagram illustrating a relationship between a porosity and an adhesive force with respect to a thermal spray rate.

FIG. 2 is a schematic cross-sectional view illustrating a configuration of a main part of a gas turbine member according to the present invention.

FIG. 3 is an optical micrograph showing a particle structure of a cross section of the present invention (test piece).

FIG. 4 is an optical micrograph showing a particle structure of a cross section of a conventional comparative example (test piece).

[Explanation of symbols]

 1 Metal substrate 2 Thermal barrier coating layer 3 Bond coat 4 Top coat

Claims (14)

[Claims] 1. A gas turbine member comprising a metal base material for a gas turbine component and a thermal barrier coating layer on the metal base material, wherein the thermal barrier coating layer comprises a bond coat and a top coat. The coat is M
A gas turbine member having a CrAlY-based composition and having a porosity smaller than that of the top coat. 2. The bond coat contains 1 wt% of Cr.
1.00 or more and 32.00 or less, Al is 5.00 or more and 14.00 or less, Y is 0.20 or more and 1.90 or less, and O ₂ is 1.00 or less, and Ni is the balance or C.
The gas turbine member according to claim 1, wherein o is 17.00 or more and 38.00 or less and has an MCrAlY-based composition containing inevitable impurities. 3. The gas turbine component according to claim 1, wherein the bond coat has a porosity of 2% or less. 4. The bond coat has an adhesion strength with respect to the metal base material of 100 MPa or more.
The gas turbine member according to claim 1. 5. The top coat is ZrO ₂ —Y ₂ O.
The gas turbine member according to any one of claims 1 to 4, which has a composition of ₃ system and has a porosity of 5% or less. 6. The bond coat has a thickness of 0.02 m.
The gas turbine member according to any one of claims 1 to 5, wherein the top coat has a thickness of 0.10 mm or more and 0.20 mm or less and the top coat has a thickness of 0.10 mm or more and 0.50 mm or less. 7. A spraying speed of 450 m / s or more to 900
A thermal barrier coating method for a gas turbine member, which comprises integrally forming a bond coat of a thermal barrier coating layer on a metal base material for a gas turbine component by using a thermal spraying method at m / s or less. 8. The thermal spray material for the bond coat, wherein Cr is 11.00 or more and 32.00 or less in weight%, Al
Is 5.00 or more and 14.00 or less, Y is 0.20 or more and 1.90 or less, and O ₂ is 1.00 or less, and N
MCrAlY in which i is the balance or Co is 17.00 or more and 38.00 or less and the composition contains inevitable impurities.
The thermal barrier coating method for a gas turbine member according to claim 7, wherein a system material is used. 9. The thermal spray material of the bond coat is 2
MCr having a powder particle size of 0 μm to 50 μm
The thermal barrier coating method for a gas turbine member according to claim 7, wherein an AlY-based material is used. 10. The thermal barrier coating method for a gas turbine member according to claim 7, wherein a high-speed gas flame spraying method is used as the spraying method. 11. The thermal barrier coating method for a gas turbine member according to claim 7, wherein a thermal spraying method using hydrogen fuel is used as the thermal spraying method. 12. A thermal barrier coating layer is integrally formed on a metal base material for gas turbine parts, and then a thermal spraying method is used in which the thermal spray rate is 350 m / s or more to 900 m / s or less. A thermal barrier coating method for a gas turbine member, wherein a top coat of the thermal barrier coating layer is integrally formed on the bond coat. 13. The thermal spray material for the top coat,
ZrO having a powder particle size of 5 μm or more and 75 μm or less
_The thermal barrier coating method for a gas turbine member according to claim 12, wherein a _2- Y ₂ O ₃ based material is used. 14. A spraying speed of 450 m / s or more to 90 or more.
A bond coat of a thermal barrier coating layer is integrally formed on a metal base material for a gas turbine member by using a thermal spraying method at 0 m / s or less, and then a thermal spraying speed of 350 m / s or more to 900 m / s or less. The thermal barrier coating method for a gas turbine member, wherein the top coat of the thermal barrier coating layer is integrally formed on the bond coat by using the thermal spraying method described above.