KR20180024053A - Thermal barrier coating structure and method of preparing the same - Google Patents

Abstract

Provided are a thermal shield coating structure, and a manufacturing method thereof. More specifically, the thermal shield coating structure includes a bonding coating layer, a buffer layer, and a topcoat layer, which are coupled on an outer surface of a base material and are sequentially stacked from the outer surface of the base material. The bonding coating layer is formed of MCrAlY (M is metal selected from a group including Ni, Co, and Fe). The buffer layer includes a first buffer layer formed with 8YSZ and a second buffer layer using mixed powder of 8YSZ and La_2Zr_2O_7. The topcoat layer is formed with the mixed powder of 8YSZ and La_2Zr_2O_7, which has a mixing ratio of La_2Zr_2O_7 greater than that of the second buffer layer. Therefore, thermal shock resistance is able to be improved in a rapid temperature change.

Description

TECHNICAL FIELD [0001] The present invention relates to a thermal barrier coating structure and a method of manufacturing the same. BACKGROUND OF THE INVENTION [0002]

The present invention relates to a thermal barrier coating structure and a manufacturing method thereof, and more particularly, to a thermal barrier coating structure capable of improving thermal shock resistance at a rapid temperature change and a method of manufacturing the same.

The thermal barrier coatings applied with the conventional YSZ (yttria-stabilized zirconia) material have a surface temperature higher than about 1200 ° C when the gas turbine system is operated at a temperature of about 1600 ° C or higher, At such a high temperature, sintering and phase change of the top coating layer occurs. As a result, the top coating layer made of the YSZ material becomes densified to deteriorate the heat shielding performance, and the base material is damaged. In addition, as the volume of the YSZ material changes due to the phase change (volume expansion of about 4%), cracks are formed in the top coating layer, resulting in peeling of the top coating layer from the base material. .

In order to improve the efficiency of the gas turbine and increase the strength, the turbine inlet temperature must be raised. However, since the thermal barrier coating using the conventional YSZ material does not provide sufficient heat shielding, New materials need to be applied to reduce the thermal load on the base metal. Particularly, when a sudden temperature change occurs in an abnormal state such as in a gas turbine which is rapidly started or stopped or in a jet engine at the time of takeoff of an aircraft, the thermal load applied to the base material is increased, do.

Therefore, the currently applied YSZ-based material can not be applied to gas turbine high temperature components where the surface temperature of the top coating layer can be increased to more than about 1200 ° C, and even when the base material temperature can rise to about 1100 ° C or more due to heat transfer There are limitations that are difficult to apply. Furthermore, the conventional YSZ materials have low corrosion resistance to CMAS (Ca, Mg, Al, Si), and it is necessary to apply new materials to increase corrosion resistance in CMAS environment where high temperature parts are experienced.

The object of the present invention is to provide a thermal spray coating structure and a method of manufacturing the same which can have good thermal barrier performance even under rapid temperature changes and have phase stability and sintering resistance even at a high temperature.

In order to solve the above problems, one aspect of the present invention provides a thermal barrier coating structure. The thermal barrier coating structure includes a bond coat layer, a buffer layer, and a top coat layer which are bonded to the outer surface of the base material and sequentially laminated from the outer surface of the base material. The bond coat layer is formed of MCrAlY (M is a metal selected from the group consisting of Ni, Co and Fe). The buffer layer includes a first buffer layer formed of 8YSZ. The top coat layer is formed of the 8YSZ and the La ₂ Zr ₂ O ₇ in combination.

The buffer layer, the first buffer layer and laminated between the top coat layer and the top coating layer, based on the volume La ₂ Zr ₂ O _7: the 8YSZ and the La ₂ Zr ₂ O in a small mixing ratio than the mixing ratio of the 8YSZ ₇ of a mixture formed of And may further include a second buffer layer.

The top coat layer on the La ₂ Zr ₂ O _7: mixing ratio (volume ratio) of 8YSZ is x: a 1-x (0.5≤x <1) , in the buffer layer La ₂ Zr ₂ O _7: mixing ratio (volume ratio) of 8YSZ is y : 1-y (0 < y < 0.5).

The mixing ratio (volume ratio) of La ₂ Zr ₂ O ₇ : 8YSZ of the top coating layer is 1: 1, and the mixing ratio (volume ratio) of La ₂ Zr ₂ O ₇ : 8YSZ of the second buffer layer is 1: 3.

The top coating layer may be thicker than the buffer layer.

The thickness of the buffer layer may be in the range of 50 μm to 150 μm, and the thickness of the top coating layer may be in the range of 200 μm to 2000 μm.

The tower is laminated on the coating layer may further include a cover layer formed of La ₂ Zr ₂ O _7.

Another aspect of the present invention provides a method of manufacturing a thermal barrier coating structure. (B) forming a bond coat layer by spraying MCrAlY (M is a metal selected from the group consisting of Ni, Co and Fe) powder on the surface of the base material; , (c) the bond 8YSZ powder onto the coating layer and the La ₂ Zr ₂ O ₇ powder, the first step of forming a buffer layer by thermal spraying a mixed powder, and (d) onto the 8YSZ powder and a La ₂ Zr ₂ O ₇ buffer layer of And spraying a second mixed powder of the powder to form a top coating layer. The mixing ratio of La ₂ Zr ₂ O ₇ : 8YSZ of the first mixed powder is smaller than the mixing ratio of La ₂ Zr ₂ O ₇ : 8YSZ of the second mixed powder based on the volume.

The step (c) includes the steps of forming a first buffer layer by spraying 8YSZ powder on the bond coat layer, and forming a second buffer layer by spraying the first mixed powder on the first buffer layer .

The manufacturing method may further include (e) forming a cover layer by spraying La ₂ Zr ₂ O ₇ powder on the top coat layer.

According to the present invention, the thermal barrier coating structure includes a buffer layer and a top coating layer deposited on the bond coat layer deposited on the outer surface of the base material so that the composition ratio of 8YSZ changes continuously, And can have high corrosion resistance in CMAS (Ca, Mg, Al, Si) environment.

In addition, the buffer layer, a top coat layer La ₂ Zr ₂ O _7: by further comprising a second buffer layer formed in a mixture of 8YSZ and La ₂ Zr ₂ O ₇ in a small mixing ratio than the mixing ratio of 8YSZ, heat adaptability caused by thermal expansion coefficient difference And the residual stress can be reduced to prevent the top coating layer from falling off, and the thermal durability of the thermal barrier coating can be secured.

In addition, by using a commercially available powder for preparing the buffer layer and the top coating layer of the thermal barrier coating structure, it is possible to reduce the time and cost for separate solid solution synthesis.

However, the effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a cross-sectional view illustrating a thermal barrier coating structure according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a thermal barrier coating structure according to embodiments of the present invention.
3 is an enlarged cross-sectional view of the specimens having the thermal barrier coating structure of FIG.
4 is a plan view showing the state of peeling after the thermal shock test according to Table 1 is performed.
Fig. 5 is a view showing a peeled section of the specimens of Fig.
6 is a plan view showing the state of peeling after the flame thermal shock test of Table 2 is carried out.
FIG. 7 is a view showing a peeled section of the specimen of FIG. 6; FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms.

In the drawings, the thicknesses of the layers and regions may be exaggerated or reduced for clarity. Like reference numerals throughout the specification denote like elements.

Thermal barrier coating structure

1 is a cross-sectional view illustrating a thermal barrier coating structure according to an embodiment of the present invention.

Referring to FIG. 1, a thermal barrier coating structure according to an embodiment of the present invention includes a bond coat layer 20, a buffer layer 30, and a top coat layer 40 that are sequentially stacked on an outer surface of a base material 10. The buffer layer 30 may include a first buffer layer 31 and a second buffer layer 33.

The base material 10 may be a component used in an aerospace-related combustion engine, a gas turbine or the like. The base material 10 may be formed of any suitable known material and may be formed of, for example, a ceramic composite material, a nickel-based super-heat-resistant alloy, a cobalt-based super-heat-resistant alloy, a titanium-based super- The surface of the base material 10 may be subjected to blast treatment before the bond coat layer 20 and the like are laminated.

The bond coat layer 20 is laminated on the surface of the base material 10. The bond coat layer 20 is laminated between the buffer layer 30 and the base material 10 such that the buffer layer 30 and the top coat layer 40 are firmly bonded on the surface of the base material 10. [ The bond coat layer 20 may be formed by an aluminiding process and preferably formed by overlay coating (atmospheric spraying, vacuum spraying, high-speed flame spraying, etc.), for example, have. Here, M is a metal selected from nickel, cobalt, iron or an alloy thereof. The buffer layer 30 includes a first buffer layer 31 laminated on the bond coat layer 20. The first buffer layer 31 is formed of 8 wt% yttria-stabilized zirconia (8YSZ). Since the first buffer layer 31 has a thermal expansion coefficient relatively comparable to that of the metal bond coat layer 20, the thermal stress and the residual stress formed at the interface are lowered due to the difference in thermal expansion coefficient between the two layers at a rapid temperature change, Durability can be maintained.

The buffer layer 30 may further include a second buffer layer 33 stacked on the first buffer layer 31. The second buffer layer 33 is formed the 8YSZ and the La ₂ Zr ₂ O ₇ (hereinafter, LZO) are mixed. The mixing ratio LZO: 8YSZ of 8YSZ and LZO based on the volume in the second buffer layer 33 may be y: (1-y) (where 0 <y <0.5). For example, the mixing ratio of LZO: 8YSZ in the second buffer layer 33 may be 1: 3 (y = 0.25).

The top coat layer 40 is deposited on the buffer layer 30. The top coating layer 40 is also formed by mixing 8YSZ and LZO. However, the mixing ratio LZO: 8YSZ of 8YSZ and LZO based on volume in the top coating layer 40 is larger than the mixing ratio in the second buffer layer 33. Specifically, the mixing ratio LZO: 8YSZ of 8YSZ and LZO in the top coating layer 40 may be x: (1-x) (where 0.5? X <1). For example, the mixing ratio of LZO: 8YSZ in the top coating layer 40 may be 1: 1 (x = 0.5).

The top coat layer 40 may have a thickness greater than that of the buffer layer 30. For example, the thickness of the buffer layer 30 may be from about 50 [mu] m to about 150 [mu] m, and the thickness of the topcoat layer 40 may be from about 200 [mu] m to about 2000 [mu] m. In general, interfacial delamination or interfacial cracking in a thermal barrier coating system occurs at 50 to 150 μm from the bond coat layer 20. If the thickness of the buffer layer 30 is thinner than 50 탆, the stress due to the difference in thermal expansion coefficient between the bond coat layer 20 and the top coat layer 40 can not be sufficiently accommodated, So that peeling can easily occur. If the thickness of the buffer layer 30 is greater than 150 탆, the heat shielding effect due to the relatively high thermal conductivity is reduced, and peeling may occur at the interface between the buffer layer 30 and the top coat layer 40 during driving. When the thickness of the top coating layer 40 is thinner than 200 탆, the heat shielding effect is reduced, so that the surface temperature of the base material can be accelerated to deteriorate the deterioration phenomenon and oxygen penetration can be facilitated and oxidation of the bond coat layer 20 can occur . If the thickness of the top coating layer 40 is greater than 2000 μm, the thermal durability may be lowered due to the thermal stress accumulated in the formation of the coating layer.

Although not shown, a cover layer formed of LZO may be further stacked on the top coating layer 40. [

As described above, as the mixing ratio of LZO: 8YSZ increases in the buffer layer 30, the top coating layer 40 and the cover layer which are laminated on the bond coat layer 20, the thermal characteristics of the thermal barrier coating structure can be continuous The buffer layer 30 having excellent fracture toughness and strength is introduced between the bond coat layer 20 and the top coat layer 40 to improve the mechanical properties of the thermal barrier coating structure by suppressing crack formation and progression at the interface have.

Method of manufacturing a thermal barrier coating structure

The method of manufacturing a thermal barrier coating structure according to an embodiment of the present invention includes an air plasma spray (APS), an electron beam physical vapor deposition (EB-PVD) method, ) Can be used. For example, electron beam evaporation can be applied to form thermal barrier coatings on blade components of aerospace-related components. Hereinafter, a method of manufacturing a thermal barrier coating structure according to an embodiment will be described in order.

First, the surface of the base material can be blasted to form a thermal barrier coating structure on the surface of the base material. For example, the surface of the base material may be blasted with alumina powder prior to forming the thermal barrier coating structure.

Next, MCrAlY powder (M is a metal selected from the group consisting of Ni, Co and Fe) is sprayed on the surface of the blasted base material to form a bond coat layer. The bond coat layer can be formed, for example, by depositing MCrAlY powder by atmospheric spraying.

Next, a first mixed powder of 8YSZ powder and LZO powder is sprayed on the bond coat layer to form a buffer layer. The first mixed powder was prepared so that the mixing ratio LZO: 8YSZ was y: (1-y) (0 <y <0.5) based on 8YSZ and LZO by volume, And may be provided as a mixture of a certain amount of time at a certain speed.

The buffer layer can be laminated by forming a first buffer layer by spraying 8YSZ powder on the bond coat layer and selectively forming a second buffer layer by spraying the first mixed powder on the first buffer layer.

Next, a second mixed powder of 8YSZ powder and LZO powder is sprayed on the buffer layer to form a top coating layer. The second mixed powder was prepared so that the mixing ratio LZO: 8YSZ of 8YSZ and LZO was adjusted to be x: (1-x) (0.5? X <1) For a certain period of time. The conditions for spraying the first mixed powder and the spraying conditions for the second mixed powder may be partially different. For example, when the second mixed powder is sprayed, the argon and hydrogen flow rates applied to the spray may vary.

Next, LZO powder is sprayed onto the top coating layer to form a cover layer. However, according to the embodiment, the cover layer may be omitted in the thermal barrier coating structure.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which: FIG. However, the following examples are intended to aid understanding of the present invention, and the present invention is not limited by the following examples.

Production Example 1

Nimonic 263 manufactured by Special Metals Co., Ltd., having a diameter of 25 mm and a thickness of 5 mm, was used as the base material, and the surface of the base material was treated through a blasting process using alumina powder before forming the thermal barrier coating structure.

The bond coat layer was deposited by spraying AMDRY 962 commercialized by METCO, a coating material of NiCrAlY based on nickel, on the surface treated base material by atmospheric spraying. METCO-3MB was used as the spray gun. The distance between the spray gun and the base material was maintained at 80 mm, and the thickness of the bond coat layer was 150 μm.

On the bond coat layer, 204 C-NS of METCO Corp., a 8 wt% yttria-stabilized zirconia (8YSZ) commercial powder, was sprayed as a buffer layer.

On the buffer layer, a mixed powder obtained by mixing LAO-109-1 of Praxair Co., Ltd. as a low thermal conductive material La ₂ Zr ₂ O ₇ as a commercial powder with 204 C-NS as a commercial powder of 8YSZ was sprayed on the top coat layer Respectively. Mix powders of La ₂ Zr ₂ O ₇ and 8YSZ were prepared by mixing powders prepared in a 50:50 volume ratio at a rotational speed of about 300 rpm for 4 hours through a ball-mill device. The topcoat layer was deposited by keeping the distance between the spray gun and the test specimen at 80 mm similar to the case of spraying the bond coat layer, but with different argon and hydrogen flow rates. The total thickness of the buffer layer and the top coating layer was set to 430 μm, and the thickness of the buffer layer was set to 60 μm.

Production Example 2

As a buffer layer, 8YSZ commercially available powder of 204 C-NS a thermal spraying to form the first buffer layer 60 μm in thickness and then, La ₂ Zr ₂ O ₇ powder, the commercialization of LAO-109-1 8YSZ powder and commercialization of 204 C-NS A thermal barrier coating structure was formed in the same manner as in Preparation Example 1, except that a second buffer layer mixed at a ratio of 25:75 was further deposited to a thickness of 60 탆 and a top coating layer was formed thereon.

Comparative Example

The same procedure as in Preparation Example 1 was followed by spraying a NiCrAlY-based commercialized powder AMDRY 962 on the blast-surfaced base material to deposit a bond coat layer. Then, LAO-109-1, a La ₂ Zr ₂ O ₇ commercial powder, 204 C-NS in a ratio of 50:50.

2 is a cross-sectional view illustrating a thermal barrier coating structure according to embodiments of the present invention.

Referring to FIG. 2, a cross-sectional structure of a thermal barrier coating structure according to Production Example 1, Production Example 2, and Comparative Example is shown. As shown in FIG. 2, in the comparative example, a top coating layer having a single composition in which La ₂ Zr ₂ O ₇ and 8YSZ were mixed at a ratio of 50:50 was formed. In Production Example 1, 8YSZ was formed as a first buffer layer at the interface of the bond coat layer at about 60 In order to provide continuity in the compositional change between the first buffer layer and the top coat layer in Production Example 2, La ₂ Zr ₂ O ₇ and 8YSZ were mixed in a ratio of 25:75 2 buffer layer was introduced. In each example, the thickness of the bond coat layer was about 150 μm, and the total thickness of the top coat layer (or top coat layer + buffer layer) deposited on the bond coat layer was maintained at about 430 μm.

3 is an enlarged cross-sectional view of the specimens having the thermal barrier coating structure of FIG.

Referring to FIG. 3, it can be seen that, in the microstructure of the specimen of the comparative example, La ₂ Zr ₂ O ₇ and 8YSZ each have a mixing ratio of 50:50 as in the design of FIG. In the test piece of Production Example 1, it was confirmed that the first buffer layer of 8YSZ was formed to a thickness of about 60 μm on the bond coat layer. In the test piece of Production Example 2, La ₂ Zr ₂ O ₇ and YSZ were formed on the first buffer layer of 8YSZ : 75 volume ratio of the second buffer layer.

Analysis example

In order to evaluate the thermal shock resistance (thermal durability) in a rapid temperature change environment for the thermal barrier coating structure produced according to Comparative Example, Production Example 1 and Production Example 2, about 50% of the top coating layer from the base material, The thermal shock test was repeated until the peeled state was exposed to the muffle furnace at 1100 占 폚 for 40 minutes and then quenched in water at room temperature for one cycle.

In addition, each specimen was exposed to a direct flame at about 1400 ° C. for 20 seconds, and subjected to a jet engine thermal shock (JETS) test in which the exposure to nitrogen gas was performed for 20 seconds in one cycle. The peeling criterion of the JETS test was set based on the fact that about 50% of the top coat layer was peeled off. Hereinafter, the experimental results of Production Example 1 and Production Example 2 will be referred to as Experimental Example 1 and Experimental Example 2, respectively.

division Number of thermal shock test runs
(number of cycles) Peeling state Comparative Example 10 Completely peeled from the top coat layer / bond coat layer interface Experimental Example 1 29 Completely peeled from the top coat layer / bond coat layer interface Experimental Example 2 54 Partial peeling in the top coat layer

Table 1 shows the number of times of the thermal shock test until the top coat layer is separated or peeled off by about 50% or more according to the thermal shock test in the experimental example, and the peeled state therefrom. 4 is a plan view showing the state of peeling after the thermal shock test according to Table 1 is performed. Fig. 5 is a view showing a peeled section of the specimens of Fig.

Referring to Table 1 and FIG. 4, in the comparative example, the top coat layer was completely peeled off after 10 cycles with the smallest number of times of the thermal shock test, and in the case of Experimental Example 1, the number of thermal shock tests was 29 Lt; RTI ID = 0.0 &gt; of &lt; / RTI &gt; On the other hand, in the case of Experimental Example 2 in which the coating structure was laminated at a continuous composition ratio by including the second buffer layer, partial peeling occurred in the top coat layer on the buffer layer after the end of 54 cycles, which is the maximum number of thermal shock test times, The dual structure buffer layer was also maintained.

5, the peeling of the top coat layer occurred near the interface where high stress was concentrated, and the position where the peeling occurred was distant from the interface in the order of Comparative Example, Experimental Example 1 and Experimental Example 2. Particularly, in Experimental Example 1 and Experimental Example 2 in which a buffer layer was introduced, excellent thermal shock resistance was exhibited. Compared with a single coating structure (Comparative Example) in which only the composition ratio (mixing ratio) of the top coating layer was controlled Is due to the advantage of accommodating the thermo-adaptive / residual stresses due to rapid temperature changes. Specifically, in the thermal barrier coating structure (comparative example) having only a single top coat layer, stresses are concentrated at the interface between the top coat layer and the bond coat layer due to a rapid temperature change, and the thermal shock resistance is lowered do. On the other hand, in the case of having a buffer layer, stresses formed by thermal shock are dispersed at the interface, and in particular, the continuity of the composition ratios of the first buffer layer and the second buffer layer of 8YSZ material having excellent mechanical properties, and the composition ratio of the second buffer layer and the top coating layer The stresses can be more easily dispersed and eliminated.

division Flame thermal shock test frequency (number of cycles) Peeling state Comparative Example 70 Completely peeled from the top coat layer / bond coat layer interface Experimental Example 1 2000 Vertical crack formation inside the top coating layer Experimental Example 2 2000 Vertical crack formation inside the top coating layer

Table 2 shows the number of times the flame thermal shock test was performed until the top coat layer was separated or peeled off by about 50% or more, and the thus-peeled state, according to the flame thermal shock (JETS) test of the experimental example. 6 is a plan view showing the state of peeling after the flame thermal shock test of Table 2 is carried out. FIG. 7 is a view showing a peeled section of the specimen of FIG. 6; FIG.

Referring to Table 2 and FIG. 6, in the comparative example, the top coat layer was completely peeled off after 70 cycles with the smallest number of flame thermal shock test times. In the case of Experimental Example 1 and Experimental Example 2, It was confirmed that the thermal shock resistance was improved by maintaining the structure.

Referring to FIG. 7, in the case of a thermal barrier coating structure (comparative example) having only a single top coat layer, in the case where there is a sudden temperature change as in an internal jet engine at the time of takeoff of an aircraft, the specimen is close to the interface between the bond coat layer and the top coat layer It can be confirmed that it is peeled off. On the other hand, the specimens of Experiment 1 and Experiment 2 in which the buffer layer was introduced showed that the top coat layer was not peeled off even after 2000 cycles. This is a result similar to the result in the thermal shock test, due to the excellent mechanical properties of the 8YSZ buffer layer and the continuity of the composition ratio including the second buffer layer.

On the other hand, vertical cracks were formed in the top coat layer of the specimens of Experimental Examples 1 and 2, and vertical cracks occurred as the 8YSZ was densified in a rapid temperature change environment. These vertical cracks play a significant role in accommodating the thermal stresses and residual stresses caused by the difference in thermal expansion coefficient, thereby further improving the thermal durability.

As described above, according to the present invention, since the thermal barrier coating structure includes the buffer layer and the top coating layer deposited on the bond coat layer deposited on the outer surface of the base material so that the composition ratio of 8YSZ continuously changes, The thermal stress and the residual stress can be reduced to prevent the top coat layer from falling off and the thermal durability of the thermal barrier coating can be secured.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

10: base metal
20: Bond coating layer
30: buffer layer
31: first buffer layer
33: second buffer layer
40: Top coating layer

Claims (10)

A buffer layer and a top coating layer which are bonded to the outer surface of the base material and are sequentially stacked from the outer surface of the base material,
Wherein the bond coat layer is formed of MCrAlY (M is a metal selected from the group consisting of Ni, Co, and Fe)
Wherein the buffer layer includes a first buffer layer formed of 8YSZ,
The top coat layer, the thermal barrier coating structure formed in a mixture of 8YSZ and La ₂ Zr ₂ O _7. The method according to claim 1,
The buffer layer may be formed,
A second buffer layer having a 8YSZ and La ₂ Zr ₂ O in a small mixing ratio than the mixing ratio of the 8YSZ ₇ are mixed: the first buffer layer and laminated between the top coat layer and in the top coat layer, based on the volume La ₂ Zr ₂ O ₇ Further comprising a thermal barrier coating structure. 3. The method of claim 2,
The mixing ratio (volume ratio) of La ₂ Zr ₂ O ₇ : 8YSZ in the top coating layer is x: 1-x (0.5? X <1)
Wherein the mixing ratio (volume ratio) of La ₂ Zr ₂ O ₇ : 8YSZ in the buffer layer is y: 1-y (0 <y <0.5). The method of claim 3,
Wherein in the top coat layer La ₂ Zr ₂ O _7: mixing ratio (volume ratio) of 8YSZ is 1: 1, wherein the La ₂ Zr ₂ in the second buffer layer O _7: mixing ratio (volume ratio) of 8YSZ was 1: 3, the thermal barrier coating rescue. The method according to claim 1,
Wherein the top coating layer is thicker than the buffer layer. 6. The method of claim 5,
Wherein the thickness of the buffer layer is from 50 [mu] m to 150 [mu] m, and the thickness of the top coating layer is from 200 [mu] m to 2000 [mu] m. The method according to claim 1,
The tower is laminated on the coating layer further comprises a cover layer formed of La ₂ Zr ₂ O _7, a train structure, barrier coating. (a) blasting the surface of the base material;
(b) spraying MCrAlY (M is a metal selected from the group consisting of Ni, Co and Fe) powder on the surface of the base material to form a bond coat layer;
(c) forming a buffer layer by spraying a first mixed powder of 8YSZ powder and ₂ Zr ₂ O ₇ powder, the La on said bond coat layer; And
(d) and forming a top coating layer by spraying a second mixed powder of 8YSZ powder and ₂ Zr ₂ O ₇ powder, the La on the buffer layer,
Wherein a mixing ratio of La ₂ Zr ₂ O ₇ : 8YSZ of the first mixed powder is smaller than a mixing ratio of La ₂ Zr ₂ O ₇ : 8YSZ of the second mixed powder based on the volume. 9. The method of claim 8,
The step (c)
Forming a first buffer layer by spraying 8YSZ powder on the bond coat layer; And
And spraying the first mixed powder onto the first buffer layer to form a second buffer layer. 9. The method of claim 8,
(e) spraying La ₂ Zr ₂ O ₇ powder onto the top coat layer to form a cover layer.

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