JP3411823B2 - High temperature member and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high temperature member having both heat shielding property and high durability and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a high temperature member used in a high temperature environment such as a gas turbine or a boiler, deterioration easily occurs due to heat. Therefore, the inside has a hollow structure and cooling air is circulated through the inside to blow out to the surface. By doing so, cooling is performed, and a heat shield layer is formed on the surface thereof to suppress heat transfer from the surface side to the inside.

The heat shield layer is formed on the surface of the base material by thermal spraying a material (for example, oxide ceramics) having a thermal conductivity smaller than that of the base material of the metal material forming the high temperature member. If the thermal barrier layer made of such a material is directly provided on the surface of the base material, it will be easily peeled off from the base material due to the difference in linear expansion coefficient with the base material. A layer is provided to improve the adhesion to the substrate. That is, as shown in FIG. 3, in the high temperature member, the bonding layer 2 is provided on the surface of the base material 1, and the heat shield layer 4 is provided on the surface of the bonding layer 2.

In a high temperature member of an industrial gas turbine,
As the material of the heat shield layer 4, zirconia partially stabilized by yttria is often used, and as the material of the bonding layer 2,
An alloy containing Cr, Al, Y or the like called MCrAlY (the balance is made of a combination of one or two elements of Ni, Co and Fe) is often used.

To form the heat shield layer 4, atmospheric plasma spraying, electron beam / physical vapor deposition, etc. are used.
A low pressure plasma spraying method, an atmospheric plasma spraying method, an electron beam / physical vapor deposition method and the like are used for forming the film.

Particularly, in the case of manufacturing a high temperature member for an industrial gas turbine, after forming a bonding layer 2 by a low pressure plasma spraying method on the surface of a base material 1 which has been soiled and roughened by alumina blast, the bonding layer 2 is formed. By forming the heat shield layer 4 by the atmospheric plasma spraying method so as not to attach dirt or the like to the surface of 2, the high temperature member can be obtained in the best balance in terms of durability and cost. The heat shield layer 4
After the formation of (1), in order to improve the adhesion between each of the base material 1, the bonding layer 2, and the ceramics layer 4, a heat treatment that also serves as an aging heat treatment of the base material 1 (for example, 843 ° C. × 24 hours) is performed.

[0007]

In the above-mentioned high temperature member, the oxide of the component contained in the bonding layer 2 and the heat shielding layer are caused by the use for a long time in a high temperature environment. It is generated between 4 and gradually growing. This oxide is indispensable for maintaining the corrosion resistance and the oxidation resistance of the bonding layer 2, but the volume expansion of the bonding layer 2 accompanying the generation and growth thereof causes the bonding layer 2 and the heat shield layer 4 to be separated from each other. It reduces the adhesion between them. Therefore, it is preferable that the oxide has a small thickness and a low growth rate, but a spinel structure oxide composed of a transition metal element of Ni or Co and Al having a high growth rate is generated. However, it has been difficult to maintain the durability of the high temperature member due to long-term use in a high temperature environment.

In view of the above, an object of the present invention is to provide a high temperature member which can maintain high durability even when it is used for a long time in a high temperature environment, and a manufacturing method thereof.

[0009]

In order to solve the above-mentioned problems, a high temperature member according to the present invention comprises a base material made of metal.
After providing a bonding layer made of MCrAlY on the surface, vacuum
By performing heat treatment at 900 ° C or higher in an environment,
Forming an α-alumina layer on the surface of the bonding layer, and subsequently,
The surface of the α-alumina layer is made of oxide-based ceramics.
It is characterized in that it is provided with a heat shield layer . High temperature mentioned above
In the member, using a heating furnace using a metal heater,
It is characterized in that heat treatment is performed.

In order to solve the above-mentioned problems, a method of manufacturing a high temperature member according to the present invention is such that a bonding layer made of MCrAlY is provided on the surface of a base material made of metal, and then heat treatment is performed at 900 ° C. or higher in a vacuum environment. Is performed to form an α-alumina layer on the surface of the bonding layer, and then the α-alumina layer is formed.
A heat shield layer made of oxide ceramics is provided on the surface of the alumina layer.

In the above-described method for manufacturing a high temperature member, the heat treatment is performed using a heating furnace using a metal heater.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which a high temperature member and a manufacturing method thereof according to the present invention is applied to a moving blade of an industrial gas turbine will be described with reference to FIG. Note that FIG. 1 is a cross-sectional view showing the structure.

As shown in FIG. 1, a base material 11 made of metal.
On the surface of, a coupling layer 12 made of an alloy called MCrAlY containing Cr, Al, Y or the like (the balance being one or a combination of two elements of Ni, Co and Fe) is formed. ing. An α-alumina layer 13 is formed on the bonding layer 12. On the α-alumina layer 13, a heat shield layer 14 made of oxide ceramics such as zirconia partially stabilized by yttria is formed.

In such a high temperature member, the base material 11
After forming the bonding layer 12 on the surface of the substrate by the low pressure plasma spraying method, under a vacuum environment (10 ⁻⁵ to 10 ⁻³ Torr), 900
It is easily manufactured by forming the α-alumina layer 13 on the bonding layer 12 by performing heat treatment at 1 ° C. or higher for 1 to 48 hours, and subsequently forming the heat shield layer 14 by the atmospheric plasma spraying method. be able to.

That is, in order to suppress the deterioration of the adhesion of the heat shield layer 14 due to long-term use in a high temperature environment and improve its durability, the α-alumina layer 13 having a low growth rate is used as the bonding layer 12. It was generated above.

When this bonding layer 12 is heat-treated under a high oxygen partial pressure, spinel oxide is produced, and when it is heat-treated below 900 ° C., δ-alumina or θ-alumina is produced. Since these oxides have a high growth rate, they may cause cracks or peeling in the heat shield layer 14. Therefore, in the present invention, after forming the bonding layer 12, it is 900 ° C. in a vacuum environment (10 ⁻⁵ to 10 ⁻³ Torr).
By performing the heat treatment for 1 to 48 hours as described above, generation of spinel oxide having a high oxidation rate is suppressed, and a dense α-alumina layer 13 having a small growth rate is formed on the bonding layer 12. is there.

Therefore, according to such a high temperature member and the manufacturing method thereof, the α-alumina layer 13 which is dense and has a slow growth rate due to long-term use in a high temperature environment.
Is formed between the bonding layer 12 and the heat shield layer 14, so that high durability is exhibited even when used for a long time in a high temperature environment.

The above-mentioned heat treatment can also serve as heat treatment for solutionizing and stabilizing the substrate 11.
It can be compatible with the heat treatment of the base material 11. Further, according to the present invention, since the α-alumina layer 13 can be first formed on the bonding layer 12 by the heat treatment based on the above-described conditions, all the MCrAlY (generally general) capable of forming α-alumina can be formed. Al content is 5-20
% By weight).

Then, in order to confirm the effect in the case of being applied to the blade of an industrial gas turbine, the following confirmation test was conducted.

IN738LC (trade name, typical composition of Daido Inco Co., Ltd.) which is generally used for rotor blades of industrial gas turbines.
16Cr-8.5Co-1.7Mo-2.6W-1.7
Ta-0.9Nb-3.4Al-3.4Ti-0.17
C-0.01B-0.1Zr-remainder Ni) was used as the substrate.

The coupling layer is made of CoNiCrAlY (typical composition: 31-33Ni-20-22Cr-7-9Al-).
0.35 to 0.65Y-remaining Co) was formed to a thickness of 0.1 mm by the low pressure plasma spraying method.

The heat shield layer was formed by yttria-stabilized zirconia (typical composition: 8Y ₂ O ₃ -ZrO ₂ ) to a thickness of 0.3 mm by atmospheric plasma spraying.

Before the formation of the bonding layer, the surface dirt of the base material was removed and the surface was roughened by alumina blasting.

First, the heat treatment conditions suitable for forming the α-alumina layer from the bonding layer were determined.

Specifically, after heat treatment is performed under the conditions of heat treatment temperature, atmosphere and time shown in Table 1 to fabricate a high temperature member, the produced oxide is identified and the cross-sectional structure is observed by X-ray diffraction method. I went. Of the heat treatment conditions shown in Table 1, 1
121 ° C x 2 hours is the solution heat treatment condition of the base material (IN738LC), and 843 ° C x 24 hours is the base material (IN73LC).
8 LC) aging heat treatment conditions.

[0026]

[Table 1]

As can be seen from Table 1, under heat treatment conditions (comparative bodies 3 and 4) in the atmosphere with a high oxygen partial pressure, 843 ° C.
The α-alumina layer was not formed at both temperatures of 1121 ° C. and 1121 ° C., and spinel oxide was formed. On the other hand, under heat treatment conditions (Comparatives 1 and 2) at a low oxygen partial pressure of 10 ⁻³ Torr or 10 ⁻⁵ Torr and a low temperature of 843 ° C.,
Θ-alumina was produced by heating for 24 hours. On the other hand, under the heat treatment conditions (Test bodies 1 and 2) at a low oxygen partial pressure of 10 ⁻³ Torr or 10 ⁻⁵ Torr and a high temperature of 1121 ° C., the α-alumina layer is formed by heating for 1 hour. confirmed.

Since the θ-alumina formed at 843 ° C. changes to the α-alumina layer at about 900 ° C.,
At least 900 to produce an α-alumina layer
It is considered that heat treatment at a temperature of ℃ or higher is necessary.

Next, in order to confirm the durability, the following heat cycle test was conducted. The test piece has a diameter of 10 mm and a length of 65 mm, and the central portion is 35 mm of a substrate made of IN738LC.
The bonding layer and the heat shield layer were formed according to the above manufacturing method. The heat treatment conditions for forming the α-alumina layer after the formation of the bonding layer were set under the environment of 10 ⁻⁵ Torr and 1121.
℃ × 2 hours, and after forming the heat shield layer 843 ℃ × 2
An aging heat treatment was performed for 4 hours (Test body 3).

Further, as a comparison body, 11 before the formation of the bonding layer.
Heat treatment is performed at 21 ° C. for 2 hours, no heat treatment is performed between the formation of the bonding layer and the formation of the heat shield layer, and 84 after the formation of the heat shield layer.
The one subjected to the aging heat treatment at 3 ° C. for 24 hours (Comparative body 5) was used.

The test method is as follows: heating in a fluidized bed furnace from 60 ° C. to 1000 ° C. for 3 minutes, then blowing compressed air from 1000 ° C. to 60 ° C. and cooling in 6 minutes until cracks or peeling are observed. Repeatedly, the number of times until the crack or peeling occurred was obtained. The results are shown in Table 2.

[0032]

[Table 2]

As can be seen from Table 2, the test body 3 having the α-alumina layer formed thereon has a thermal cycle resistance which is about four times or more that of the comparative body 5 having no α-alumina layer and is excellent in durability. I was able to confirm.

An embodiment in which the high temperature member and the manufacturing method thereof according to the present invention is applied to a stationary blade of an industrial gas turbine will be described with reference to FIG. Note that FIG. 2 is a cross-sectional view showing the structure. However, description of the same parts as those in the above-described embodiment will be omitted.

As shown in FIG. 2, a bonding layer 22 is formed on the surface of the base material 21 of the high temperature member. An α-alumina layer 23 is formed on the bonding layer 22. A heat shield layer 24 is formed on the α-alumina layer 23.

In such a high temperature member, the base material 21
After forming the bonding layer 22 on the surface of the substrate by a low pressure plasma spraying method, a resistance heating furnace using a metal heater is used to perform heat treatment at 900 ° C. or higher for 1 to 48 hours in a vacuum environment (1
0 ^-5 to 10 ^-3 Torr) to obtain the bonding layer 22.
It can be easily manufactured by forming the α-alumina layer 23 thereon and then forming the heat shield layer 24 by the atmospheric plasma spraying method.

That is, in the present embodiment, the heating is performed using the resistance heating type heating furnace using the metal heater.

This is because, when the above-mentioned heat treatment is performed at a temperature of 900 ° C. or higher where the α-alumina layer can exist in the most energy stable state, when the oxygen partial pressure is high, spinel oxide having a high growth rate is preferentially produced. Therefore, it is necessary to suppress the formation of spinel oxide and generate α-alumina by performing heat treatment in a vacuum environment with a low oxygen partial pressure. Type heating furnace or high-frequency heating type heating furnace in which an induction current is passed through carbon to heat it by Joule heat due to its electrical resistance, heat treatment is performed in the presence of high-temperature carbon. However, due to the reducing action of carbon, not only the α-alumina layer but also no oxide is formed.

Therefore, according to such a high temperature member and its manufacturing method, the α-alumina layer 23 is dense and has a slow growth rate due to long-term use in a high temperature environment.
Is formed between the bonding layer 22 and the heat shield layer 24, so that high durability is exhibited even when used for a long time in a high temperature environment.

Among the materials used for the stationary blades of industrial gas turbines, ECY768 has no heat treatment condition for material adjustment, but has IN heat treatment condition for material adjustment such as IN939. The Ni-base superalloy can be subjected to both solution heat treatment and stabilization heat treatment and heat treatment for forming the α-alumina layer 23. Further, similarly to the case of the above-described embodiment, the aging heat treatment is performed after the heat shield layer is formed.

Then, in order to confirm the effect when applied to the stationary blade of the industrial gas turbine, the following confirmation test was conducted.

ECY768 (typical composition: 23.5Cr-10Ni) commonly used for stationary blades of industrial gas turbines.
-7W-3.5Ta-0.25Ti-0.18Al-
0.60 C-remainder Co) was used as the substrate.

The bonding layer was made of CoNiCrAlY (typical composition: 31 to 33Ni-20 to 22Cr-7 to 9Al-).
0.35 to 0.65Y-remaining Co) was formed to a thickness of 0.1 mm by the low pressure plasma spraying method. Although the durability may decrease, the manufacturing cost can be reduced, so that HVOF (High Velocity Oxi-Fu)
El Flame Spray: Ultra-high speed flame spraying) can be used to form the bonding layer.

The heat shield layer was formed by yttria-stabilized zirconia (typical composition: 8Y ₂ O ₃ -ZrO ₂ ) to a thickness of 0.3 mm by atmospheric plasma spraying.

Before forming the bonding layer, the surface stain of the base material was removed and the surface was roughened by alumina blasting.

First, heat treatment conditions suitable for forming an α-alumina layer from the bonding layer were determined.

Specifically, after heat treatment is performed under the conditions of heat treatment temperature, atmosphere, time and heating furnace heater wire material shown in Table 3 to fabricate a high temperature member, the produced oxide is formed by X-ray diffraction. Identification and observation of cross-sectional structure were performed.

[0048]

[Table 3]

As can be seen from Table 3, under heat treatment conditions (comparative bodies 8 and 9) in the atmosphere with a high oxygen partial pressure, 850 ° C.
At both temperatures of 1080 and 1080 ° C., no α-alumina layer was formed, and spinel oxide was formed. On the other hand, 1080 ° C in a vacuum environment using a heating furnace using a carbon heater
Under the heat treatment condition of heating for 2 hours (Comparative body 6), no oxide was identified. Furthermore, in a vacuum environment using a heating furnace using a metal (molybdenum) heater, 85
Heat treatment condition of heating at 0 ° C. for 24 hours (Comparative body 7)
Then, θ-alumina was produced. In contrast,
Formation of an α-alumina layer was confirmed under heat treatment conditions (Test sample 4) in which heating was performed at 1080 ° C. for 2 hours in a vacuum environment using a heating furnace using a metal (molybdenum) heater.

The type of alumina produced generally changes from θ-alumina to α-alumina layer at about 900 ° C. Therefore, in order to form the α-alumina layer, it is necessary to perform heat treatment at least at 900 ° C. or higher using a heating furnace using a heater wire that does not have a reducing action, such as a carbon heater.

Next, in order to confirm the durability, the following heat cycle test was conducted. In the test body, a bonding layer and a heat shield layer were formed on the central portion 35 mm of an ECY768 base material having a diameter of 10 mm and a length of 65 mm according to the above-described manufacturing method. The heat treatment conditions for forming the α-alumina layer after forming the bonding layer were set to 1080 ° C. × 2 hours in a vacuum environment in a heating furnace using a metal heater, and further, the adhesion between the bonding layer and the heat shield layer. 850 ° C after formation of heat shield layer for improvement
An aging heat treatment was performed for 24 hours (Test body 5).

Further, as a comparative body, one using a heating furnace using a carbon heater in place of the heating furnace using a metal heater (comparative body 10) was subjected to heat treatment at 1080 ° C. for 2 hours before forming the bonding layer. A heat treatment was not performed between the formation of the bonding layer and the formation of the heat shield layer, and an aging heat treatment of 850 ° C. × 24 hours was performed after formation of the heat shield layer (Comparative body 11).

The test method was as follows: heating in a fluidized bed furnace from 60 ° C. to 1000 ° C. for 3 minutes, then blowing compressed air from 1000 ° C. to 60 ° C. and cooling in 6 minutes until cracks or peeling were observed. Repeatedly, the number of times until the crack or peeling occurred was obtained. The results are shown in Table 4.

[0054]

[Table 4]

As can be seen from Table 4, the test body 5 having the α-alumina layer formed thereon is the comparative body 1 having no α-alumina layer.
It was confirmed that it has a heat cycle resistance of about 2 to 3 times that of 0, 11 and has excellent durability.

[0056]

The high temperature member according to the present invention is made of metal.
A bonding layer made of MCrAlY was provided on the surface of the base material.
After that, by performing a heat treatment at 900 ° C or higher in a vacuum environment.
To form an α-alumina layer on the surface of the bonding layer,
The oxide ceramic on the surface of the α-alumina layer.
Since a heat shield layer made of a carbon is provided , an α-alumina layer that is dense and has a slow growth rate due to long-term use in a high temperature environment exists between the bonding layer and the heat shield layer. Also, high durability is exhibited even when used for a long time in a high temperature environment. Also, use a heating furnace that uses a metal heater.
If the heat treatment is performed on the surface of the bonding layer, α-
The alumina layer is surely formed.

On the other hand, in the method of manufacturing a high temperature member according to the present invention, a bonding layer made of MCrAlY is provided on the surface of a base material made of metal, and then heat treatment is performed at 900 ° C. or higher in a vacuum environment to perform the bonding. Since the α-alumina layer was formed on the surface of the layer and subsequently the heat shield layer made of oxide ceramics was provided on the surface of the α-alumina layer, long-term use in a high temperature environment was possible. However, a high temperature member capable of exhibiting high durability can be easily manufactured. Further, since the above-mentioned heat treatment can also serve as solution heat treatment or stabilization aging heat treatment of the base material, the durability of the high temperature member can be improved without increasing the cost.

If the heat treatment is carried out using a heating furnace using a metal heater, the α-alumina layer can be surely formed on the surface of the bonding layer.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of an embodiment in which a high temperature member according to the present invention is applied to a moving blade of an industrial gas turbine.

FIG. 2 is a cross-sectional view showing a structure of an embodiment when a high temperature member according to the present invention is applied to a stationary blade of an industrial gas turbine.

FIG. 3 is a cross-sectional view showing the structure of a conventional high temperature member.

[Explanation of symbols]

11,21 Base material 12,22 Coupling layer 13,23 α-alumina layer 14,24 Heat shield layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C23C 28/00 C23C 28/00 A (72) Inventor Keiichi Moriya 2-1-1 Nihama, Arai-cho, Takasago-shi, Hyogo Mitsubishi Heavy Industries Ltd. Takasago Research Institute (56) Reference JP-A-9-310168 (JP, A)

Claims (4)

(57) [Claims] 1. A surface of a metal substrate is coated with MCrAl.
After providing the bonding layer made of Y, in a vacuum environment, 900 ° C or higher
When the heat treatment is performed on the surface of the bonding layer, α-
An alumina layer is formed, and then the surface of the α-alumina layer is formed.
A high temperature member having a heat shield layer made of oxide ceramics on its surface . 2. Using a heating furnace that uses a metal heater
The heat treatment according to claim 1, wherein the heat treatment is performed.
High temperature member. 3. MCrAl is formed on the surface of a base material made of metal.
After the bonding layer made of Y is provided, a heat treatment is performed at 900 ° C. or higher in a vacuum environment to form α-on the surface of the bonding layer.
A method of manufacturing a high-temperature member, comprising forming an alumina layer and subsequently providing a heat shield layer made of oxide ceramics on the surface of the α-alumina layer. 4. The method for manufacturing a high temperature member according to claim 3 , wherein the heat treatment is performed using a heating furnace using a metal heater.