KR20170034252A - Method for forming thermal barrier coating layer and thermal barrier coating layer formed by the same - Google Patents

Abstract

Disclosed are a method for forming a thermal barrier coating layer and a thermal barrier coating layer formed thereby. According to the present invention, the method for forming a thermal barrier coating layer comprises the following steps of: forming an alumina layer on a metal base material surface by heat treating a metal base material containing aluminum at 1100-1150C in a vacuum condition of 10-9 atm to 10-12 atm of oxygen partial pressure; and forming a ceramic coating layer on a surface of the alumina layer.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of forming a thermal barrier coating layer and a thermal barrier coating layer formed by the method.

The present invention relates to a method of forming a thermal barrier coating layer and a thermal barrier coating layer formed thereby. More particularly, the present invention relates to a method for forming a thermal barrier coating layer which is capable of forming a stable oxide layer at an elevated temperature and having equivalent functions without directly coating the metal powder on the surface of the base material by high temperature heat treatment at a low oxygen partial pressure And a thermal barrier coating layer formed by the thermal barrier coating layer.

For aviation and power generation gas turbines, the turbine inlet temperature (TIT) or the combustion temperature is operated above 1,000 ℃ to obtain high thermal efficiency. In this operating environment, parts that come into direct contact with high temperature combustion gases are mostly made of nickel-base or cobalt-base superalloy with high heat resistance.

For example, a bond coat (MCrAlY, M = Ni, Co) or bond coat + zirconia (zirconia) may be added to components such as a first stage blade, a vane, ZrO2) based thermal barrier coating (TBC) is applied to a thickness of 200 m or more.

The conventional thermal spray coating method is performed by laminating a material having a low thermal conductivity on a surface of a material to slow heat transfer and to shield the heat of the high temperature combustion gas due to the internal pores formed during coating. At this time, the thermal barrier coating system is composed of two coating layers.

At this time, the outermost layer has a ceramic coating layer that directly shields heat. However, due to the difference in thermal expansion coefficient between the ceramic coating layer and the base metal, the ceramic coating layer is easily peeled off in a repeated operating environment of high temperature and low temperature. In order to compensate for this, a metal component having a coefficient of thermal expansion between the base metal and the ceramic coating layer is coated on the base metal, which is referred to as a metal bond (metal bond) coating.

Such a metal bond coat layer facilitates bonding between the ceramic coating layer and the metal base material and prevents high temperature oxidation of the metal base material due to external harsh environment. This is due to the principle that stable aluminum oxide is formed at the interface between the ceramic coating layer and the metal bond coat layer to prevent movement of the metal element in the opposite direction to the oxygen coming from the outside to the inside.

FIG. 1 is a flow chart schematically showing a method of forming a thermal barrier coating layer according to the conventional invention, and FIG. 2 is a cross-sectional view schematically showing a thermal barrier coating layer formed by a conventional invention.

Referring to FIGS. 1 and 2, the conventional thermal spray coating is performed by blasting the base material 10 to form surface irregularities, and then cleaning the surface with acetone or the like to remove contaminants on the surface. Next, the surface of the base material 10 is preheated, and then the surface of the base metal material 10 is coated with a metal alloy powder (component: MCrAlY, M = Ni or / and Co) by using a high-temperature plasma in vacuum, . After that, ceramic coating (YSZ: yttria-stabilized zirconia, ZrO2-8Y2O3) is used for heat-shielding, and finally post-heat treatment is carried out. The aluminum oxide layer 30 is formed at the interface between the metal bond coat layer 20 and the ceramic coating layer 50 by the post heat treatment to protect the base material 10 from high temperature oxidation.

However, according to this conventional method, the cost of the plasma spray coating equipment, the metal alloy powder, the processing time and the work force is large and the cost of the plasma spray coating equipment, There arises a problem that an undesired image is generated due to the occurrence of a shift in the image.

An object of the present invention is to provide a coating layer which is capable of forming a stable oxide layer at an elevated temperature even when the metal base material is subjected to a high-temperature heat treatment under a low oxygen partial pressure condition without having a metal powder directly coated on the surface of the base material.

Another object of the present invention is to provide a coating layer which is cost-effective, requires a shorter processing time, and is capable of forming an efficient new intermediate bonding layer.

It is still another object of the present invention to provide a coating layer which prevents movement of constituent elements due to a difference in composition between a base material and a metal bond coat layer to prevent an undesired phase from being generated.

It is still another object of the present invention to provide a coating method which is superior in bonding strength to physical bonding of a metal intermediate bonding layer by an outer coating by producing chemical bonding by stable oxides formed using aluminum present in a base material.

Still another object of the present invention is to provide a coating method which can form a ceramic coating layer thicker by a thickness required for an original metallic intermediate bonding layer, thereby realizing an excellent heat shielding function and a coating soundness.

It is another object of the present invention to provide a coating method which can be applied not only to a gas turbine of a power generation facility but also to an aircraft gas turbine engine and is continuously applicable during operation of the facility, .

The above and other objects of the present invention can be achieved by the present invention described below.

One aspect of the present invention is to heat-treat a metal base material containing aluminum at a temperature of 1100 to 1150 占 폚 under a vacuum condition of an oxygen partial pressure of 10 ^-9 atm to 10 ^-12 atm to form an alumina layer on the surface of the metal base material; And forming a ceramic coating layer on the surface of the alumina layer.

In an embodiment, the metal matrix is a nickel-based or cobalt-based superalloy for gas turbine components containing aluminum (Al) in an amount of 5 to 20 wt%.

In a specific example, the method further includes pretreatment before the heat treatment in the vacuum condition.

In an embodiment, the alumina layer is in contact with the metal base material, and a metal bonding layer is not formed between the alumina layer and the base metal material.

In the specific example, the heat treatment is performed at a temperature of 200 to 400 ° C / min, maintained at a temperature of 1100 to 1150 ° C, and slowly cooled.

Another aspect of the present invention relates to an alumina layer formed on a surface of a metal base material containing aluminum; And a ceramic coating layer formed on the surface of the alumina layer, wherein the alumina layer has a surface roughness of 30 nm to 60 nm (Ra).

In an embodiment, the metal base material is a nickel-based or cobalt-based superalloy for gas turbine components containing aluminum (Al) in an amount of 5 to 20 wt%.

In an embodiment, the alumina layer is in contact with the metal preform, and a metal bonding layer is not present between the alumina layer and the metal preform.

In an embodiment, the alumina layer has a layer thickness of 0.001 탆 to 1 탆, and the ceramic coating layer has a layer thickness of 200 탆 to 500 탆.

The method of forming a thermal barrier coating layer according to the present invention and the thermal barrier coating layer formed thereby can form a stable oxide layer even at a high temperature without forming a separate metal powder coating layer by high temperature heat treatment under a low oxygen partial pressure condition, It is possible to form a new intermediate bonding layer which is shorter in the process time and is efficient. In addition, the present invention can prevent an undesired phase from being generated due to a movement between constituent elements due to a difference in composition between the base metal and the coating layer, and the stable oxide formed using the aluminum present in the base material chemically bonds The bonding strength is superior to the physical bonding of the metal intermediate bonding layer by the outer coating. Further, the present invention can form a ceramic coating layer thicker by the thickness required for the original metal intermediate bonding layer, thereby realizing excellent heat-shielding function and coating integrity, and can be applied not only to a gas turbine of a power generation facility but also to an aircraft gas turbine engine And can be continuously applied during operation of the facility, which has the same life cycle as the facility.

1 is a flowchart schematically showing a method of forming a thermal barrier coating layer according to the prior art.
2 is a cross-sectional view schematically showing a thermal barrier coating layer formed by the conventional invention.
3 is a flowchart schematically showing a method of forming a thermal barrier coating layer according to the present invention.
4 is a cross-sectional view schematically showing a thermal barrier coating layer formed by the present invention.
5 is an image showing the surface structure of a metal base material heat-treated in the atmosphere according to Comparative Example 1. Fig.
6 is an image showing a cross-section of a metal base material heat-treated in air according to Comparative Example 1. Fig.
7 is an image showing the surface structure of a metal base material heat-treated at a low oxygen partial pressure according to Example 1. Fig.
8 is an image showing a cross section of a metal base material heat-treated at a low oxygen partial pressure according to Example 1;

Embodiments of the present application will now be described in more detail with reference to the accompanying drawings. However, the techniques disclosed in the present application are not limited to the embodiments described herein but may be embodied in other forms.

The embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the present application to those skilled in the art. In the drawings, the width, thickness, and the like of the components are enlarged in order to clearly illustrate the components of each device. In addition, although only a part of the components is shown for convenience of explanation, those skilled in the art can easily grasp the rest of the components.

It is to be understood that when an element is described above as being located above or below another element, it is to be understood that the element may be directly on or under another element, It means that it can be done. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. In the drawings, the same reference numerals denote substantially the same elements.

It is to be understood that the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise, and the terms "comprise" Components, components, or combinations thereof, and does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof .

Further, in carrying out the method or the manufacturing method, the respective steps of the method may take place differently from the stated order unless clearly specified in the context. That is, each process may occur in the same order as described, may be performed substantially concurrently, or may be performed in the opposite order.

Hereinafter, the present invention will be described in more detail.

Train waste  Coating layer forming method

A method of forming a thermal barrier coating layer which is one aspect of the present invention is a method of forming a thermal barrier coating layer by heat-treating a metal base material containing aluminum at a temperature of 1100 to 1150 캜 under a vacuum of 10 ^-9 atm to 10 ^-12 atm, (S100), and forming a ceramic coating layer on the surface of the alumina layer (S200).

Each step of the method for forming a thermal barrier coating layer according to the present invention will be described in detail below.

3 is a flowchart schematically showing a method of forming a thermal barrier coating layer according to the present invention.

Referring to FIG. 3, the thermal spray coating layer forming method of the present invention includes an alumina layer forming step (S100) and a ceramic coating layer forming step (S200).

Alumina layer formation

It said aluminum oxide layer forming step (S100) is the base metal containing aluminum oxygen partial pressure is 10 ^{- 9 -12} atm to 10 atm by heating at 1100 to 1150 ℃ in vacuum conditions for the purpose of forming an alumina layer on the base metal surface .

The alumina layer when forming the metal base material 10, the oxygen partial ^{pressure-lowering} the oxygen partial pressure to a low oxygen condition in the vacuum of ⁹ atm to 10 ^-12 atm, stable in accordance with the principles of oxide generated in a metal surface in accordance with the oxygen partial pressure at a constant temperature that varies To form aluminum oxide.

The low oxygen partial pressure, and then charged to the base metal in the chamber oxygen partial pressure, for 10 ^-9 atm to about 10 ^-12 atm, for example, 10 ^may be performed in a manner that reduces the ¹⁰ atm to 10 ^-11 atm. In the range of the low-oxygen partial pressure, the metal intermediate bonding layer is heat-treated without external coating to form a stable oxide layer having a function equivalent to that of a high temperature without forming a metal bond coat layer.

The reduction of the oxygen partial pressure can be repeated 3 to 10 times for 30 minutes to 90 minutes, for example, for 40 minutes to 80 minutes, for example, for 50 minutes to 60 minutes, . It is possible to more easily lower the oxygen partial pressure inside the vessel by a conventional low-performance vacuum pump without resorting to a high vacuum pump in the above reduction range. At this time, for example, argon (Ar) gas may be used as the inert gas.

The high-temperature heat treatment may be performed by heat-treating the metal base material at 1100 to 1150 ° C, for example, at 1110 to 1140 ° C, for example, at 1120 to 1130 ° C for 15 to 120 minutes, And then charging the furnace to raise the temperature and then cooling the furnace. In the high-temperature heat treatment range, it is possible to form a stable and dense aluminum oxide layer at a high temperature by merely performing a heat treatment by lowering the oxygen partial pressure. Various processes such as coating, blasting and preheating by the expensive plasma spray, To reduce the cost and to further form a ceramic coating layer by the thickness of the intermediate bonding layer by the outer coating, thereby improving the heat shielding function.

The temperature rise can be performed at a temperature of 200 to 400 占 폚 / min, for example, 250 to 350 占 폚 / min, for example, 300 to 330 占 폚 / min. The metal base material can be gradually cooled by shutting off the power supply to the furnace after a certain period of time in the temperature raising range. At this time, the cooling of the metal base material is performed by the slow cooling method, and it is possible to prevent the stable aluminum oxide generated on the surface of the metal base material from falling off due to the thermal stress due to the rapid cooling.

Formation of ceramic coating layer

The ceramic coating layer forming step (S200) is performed for forming a ceramic coating layer directly on the metal base material without forming a metal bond coat layer as an intermediate bonding layer on the surface of the alumina layer.

Since the ceramic coating layer is formed, heat can be directly shielded from the outermost part of the base material, and a stable oxide layer can be formed without external coating, so that the ceramic coating layer can be formed thicker by the thickness required for the original metal intermediate bonding layer, Function and coating integrity can be realized.

The ceramic coating layer may be formed by a well-known method. For example, a ceramics coating layer can be formed by a conventional method using yttria-stabilized zirconia (ZrO2-8Y2O3) or the like. However, if the object of the present invention can be realized, the method is not limited thereto.

Pretreatment

The pretreatment step of the surface of the base material may be further included before the heat treatment in the vacuum condition. The pretreatment step may be performed for cleaning the surface of the base material 10 with acetone or the like to remove oil components and contaminants, .

In the pretreatment step of the surface of the base material, an oxide layer, which is an alumina layer, can be easily formed through washing and drying, and in particular, a single oxide layer can be densely formed without forming pores on the surface, have.

As described above, according to the method of forming a thermal barrier coating layer of the present invention, it is possible to form a stable oxide layer at a high temperature without coating the metal powder directly on the surface of the base material by high temperature heat treatment under a low oxygen partial pressure condition, , Shortening the process time, and increasing the life cycle of the equipment.

Train waste  Coating layer

Another aspect of the present invention is a thermal barrier coating layer comprising: an alumina layer formed on a surface of a metal base material containing aluminum; And a ceramic coating layer formed on the surface of the alumina layer, wherein the alumina layer has a surface roughness of 30 nm to 60 nm (Ra).

Hereinafter, the thermal barrier coating layer of the present invention will be described in detail.

4 is a cross-sectional view schematically showing a thermal barrier coating layer formed by the present invention.

4, the thermal spray coating layer 100 according to the present invention includes an alumina layer 30 formed on the surface of a metal base material 10 containing aluminum and a ceramic coating layer 50 formed on the surface of the alumina layer 30 ).

Metal base material

The metal base material 10 may be a nickel-based or cobalt-based superalloy for gas turbine components. In order to obtain the high thermal efficiency of the system, the gas turbines for aviation and power generation are operated at a turbine inlet temperature or a combustion temperature of 1,000 ° C or higher. In such an operating environment, parts which are in direct contact with the high temperature combustion gas are required to have high heat resistance , It is preferable to use a nickel-based or cobalt-based superalloy as the base material.

The metal base material 10 may be a nickel-based or cobalt-based superalloy for gas turbine components containing aluminum (Al) in an amount of 5 to 20% by weight. In one embodiment, the superalloy, which is the metal base material 10, comprises 5 to 10 wt% cobalt, 5 to 10 wt% chromium (Cr), 0.5 to 3.0 wt% tungsten (W) (Ta), 5 to 20 wt% aluminum (Al), 0.5 to 3.0 wt% titanium (Ti), 0.1 to 2.0 wt% beryllum (Re), and balance nickel (Ni). At this time, the aluminum (Al) may be, for example, 5 to 20 wt%, for example, 7 to 17 wt%, for example, 10 wt% to 100 wt% of the nickel- or cobalt- To 15% by weight. In the aluminum content range, heat and oxygen of the combustion gas are shielded to have strong heat resistance, so that the occurrence of problems such as cracks in the parts directly in contact with the high temperature combustion gas can be reduced.

Alumina layer

The alumina layer 30 is formed on the surface of the metal base material 10 and is an oxide layer formed to be stabilized at a high temperature having an equivalent function without the outer coating of the metal intermediate bonding layer.

The alumina layer (30) is in contact with the metal base material (10), and there is no metal bonding layer between the alumina layer and the base metal material. This layer structure prevents the movement of the metal element in a direction opposite to the oxygen that enters from the outside of the metal base material 10 and facilitates the bonding between the base material 10 and the ceramic coating layer 50, It is possible to prevent the metal base material 10 from being oxidized at a high temperature.

The alumina layer 30 may have a layer thickness of 0.001 탆 to 1 탆, for example, 0.01 탆 to 0.8 탆, for example, 0.1 탆 to 0.7 탆. When the layer thickness of the coating layer is less than 0.001 탆, permeation of oxygen or metal ions through the alumina layer is facilitated and the improvement of the oxidation resistance characteristic becomes insignificant. On the other hand, when the layer thickness of the coating layer exceeds 1 탆 There is a problem that the coating layer is easily peeled off due to an internal stress of the coating layer itself or an external stress due to a difference in thermal expansion coefficient from the metal base material.

Ceramic coating layer

The ceramic coating layer is formed on the surface of the alumina layer 30 of the thermal barrier coating layer 100 according to an embodiment of the present invention.

The ceramic coating layer 50 directly shields heat at the outermost layer. In the present invention, a ceramic coating layer can be formed directly on the metal base material without forming a metal bond coat layer.

The ceramic coating layer 50 has a layer thickness of 200 탆 to 500 탆, for example, 250 탆 to 450 탆, for example, 300 탆 to 400 탆. If the layer thickness of the coating layer is less than 200 탆, the heat shielding function due to the formation of the ceramic coating layer is insufficient. On the other hand, when the thickness of the coating layer is more than 500 탆, It is difficult to increase the thickness of the ceramic coating layer so that damage is likely to occur and the effect of improving the heat shielding effect can not be realized.

The thermal spray coating layer according to the present invention may have a surface roughness of 30 nm to 60 nm (Ra) under a low oxygen partial pressure condition, for example, from 35 nm to 55 nm (Ra) (Ra). The change in surface roughness indicates that the reaction occurred on the surface during the heat treatment of the metal base material. It can be seen that, in the surface roughness range, there is an effect that only one layer of aluminum oxide having a stable cross-section is formed densely without forming pores on the surface of the base material when forming the thermal barrier coating layer according to the present invention.

The thermal barrier coating layer according to the present invention has an equivalent function without directly coating the metal powder on the surface of the base material and forms a stable oxide layer even at a high temperature, It is possible to apply the present invention to a power generation facility or an aircraft gas turbine engine by implementing a lung function and a coating soundness.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example

Example 1

Nickel-based superalloys for gas turbine components with a composition of Ni-9.5Co-7.7Cr-1.9W-2.1Ta-12.8Al-1.4Ti-1.1Re (at. The base material was cut into 2X2 (width X length) cm specimens, and the specimens were polished to a level of # 2000 SiC using abrasive paper to make the surface conditions the same.

Then, the specimens were washed in an ultrasonic washing machine using acetone and alcohol, and the washed specimens were completely dried with compressed air. Then, the surface roughness of the dried specimen was measured.

The prepared specimens were placed in an alumina boat and placed in a reaction vessel composed of a quartz tube and a vacuum pump. And then charged into a tube furnace maintained at 1150 ° C under hypoxic partial pressure (10 ^-9 atm). At this time, the temperature of the specimen was measured in real time by the thermocouple connected separately.

The furnace power was shut off about 15 minutes after the sample temperature reached the set temperature. The surface roughness of the alumina layer was then measured after cooling. Then a ceramic coating (YSZ: yttria stabilized zirconia, ZrO2-8Y2O3) was performed. Thereafter, a post-heat treatment (temperature 1100 ° C, time 120 min, pressure 10 ^-2 atm) was performed.

Example 2

A thermal barrier coating layer was formed under the same conditions as in Example 1, except that the oxygen partial pressure was set to a low oxygen partial pressure of 10 ^-10 atm.

Example 3

A thermal barrier coating layer was formed under the same conditions as in Example 1, except that the oxygen partial pressure was set at a low oxygen partial pressure of 10 ^-11 atm.

Example 4

A thermal barrier coating layer was formed under the same conditions as in Example 1, except that the oxygen partial pressure was set at a low oxygen partial pressure of 10 ^-12 atm.

Comparative Example 1

A thermal barrier coating layer was formed under the same conditions as in Example 1, except that oxygen partial pressure was applied at atmospheric pressure to form a thermal barrier coating layer.

Comparative Example 2

A thermal barrier coating layer was formed under the same conditions as in Example 1, except that oxygen partial pressure was applied under high oxygen (10 ^-6 atm) partial pressure during formation of the thermal barrier coating layer.

Comparative Example 3

A thermal barrier coating layer was formed under the same conditions as in Example 1, except that oxygen partial pressure was applied under high oxygen (10 ^-3 atm) partial pressure during formation of the thermal barrier coating layer.

Comparative Example 4

A thermal barrier coating layer was formed under the same conditions as in Example 1, except that the heat treatment temperature was set at a low temperature (800 ° C) in forming a thermal barrier coating layer.

Comparative Example 5

A thermal barrier coating layer was formed under the same conditions as in Example 1 except that the thermal barrier coating layer was formed at a low temperature elevating temperature (100 ° C / min).

Comparative Example 6

The surface of the base material is pre-heated, and then the metal alloy powder (MCrAlY, M = Ni or / Mo) is added to the surface of the base material by washing with acetone or the like after blasting the metal base material by the conventional method, and Co were coated on the surface of the metal base material by using a high-temperature plasma in a low vacuum, and then a ceramic coating (YSZ: yttria-stabilized zirconia, ZrO2-8Y2O3) was finally performed and post-heat treatment was performed to form a thermal barrier coating layer .

Example 1 Example 2 Example 3 Example 4 Heat treatment Oxygen partial pressure
(ATM) 10 ^-9 10 ^-10 10 ^-11 10 ^-12 Temperature
(° C) 1150 1140 1110 1120 duration
(min) 30 45 40 25 Heating rate
(° C / min) 200 250 230 300 Ceramic coating layer ○ ○ ○ ○ Surface roughness nm (Ra) 53 55 51 48

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Heat treatment Oxygen partial pressure
(ATM) Atmospheric pressure 10 ^-6 10 ^-3 10 ^-9 10 ^-12 - Temperature
(° C) 1150 1140 1110 800 1000 - time
(min) 30 45 40 25 25 - Heating
(° C / min) 200 250 230 300 100 - Metal bond coat layer X X X X X ○ Ceramic coating layer ○ ○ ○ ○ ○ ○ Surface roughness nm (Ra) 280 190 155 100 95 317

Property evaluation

The surface roughness of the metal matrix was measured during the heat treatment. The change in surface roughness indicates that the reaction took place on the surface of the base metal. For comparison of the surface roughness, the prior surface roughness was first measured, and as a result, it was in the range of 14 to 22 nm (Ra). Then, the surface roughness of each of the metal base specimens was measured according to Examples 1 to 4 and Comparative Examples 1 to 5, which are shown in Tables 1 and 2 above.

Measurement result

5 is an image showing the surface structure of a metal base material heat-treated in the atmosphere according to Comparative Example 1. Fig.

Referring to FIG. 5, it can be seen that an oxide layer having a large number of pores is formed on the surface when the oxygen partial pressure is lowered in the atmosphere in the process of heat treatment of the metal base material as in Comparative Example 1, .

6 is an image showing a cross-sectional appearance of a metal base material heat-treated in the atmosphere according to Comparative Example 1. Fig.

Referring to FIG. 6, a pore cross section formed on the surface of the metal base material of Comparative Example 1 shows that the oxide layer is composed of several layers. At this time, the outermost layer is an oxide layer containing nickel as a main component. Such an oxide has a high growth rate at a high temperature and can not prevent oxygen penetration into the inside, so that it can not serve as an intermediate bonding layer. And an oxide layer mainly composed of titanium and tantalum is formed in the lower layer. This also has no protective coating properties like the upper nickel oxide layer. Finally, there is a black continuous phase at the boundary with the base metal. This layer is an aluminum oxide layer and has a protective coating property. However, the presence of the upper two layers does not contribute to the bonding force with the ceramic layer, and the two layers are rapidly grown at a high temperature, so that the entire thermal barrier coating is peeled off. Therefore, as in Comparative Example 1, when the heat treatment is performed in the air without controlling the oxygen partial pressure, the oxide layer having many pores is formed and the bonding force with the ceramic layer is decreased, And the surface roughness is also very high compared to the previously measured 22 nm (Ra) at 280 nm (Ra).

Further, when the oxygen partial pressure condition is 10 ^-6 atm of Comparative Example 2 and the oxygen partial pressure conditions, such as 10 ^-3 atm in Comparative Example 3, but to adjust the oxygen partial pressure during heat treatment of the base metal and to perform at an oxygen partial pressure conditions, the It can be seen that the surface roughness is 190 nm (Ra) and 155 nm (Ra) higher than the previously measured surface roughness.

Also, as compared with the present invention, it can be seen that the surface roughness of the thermal barrier coating layer is low and it is difficult to form a stable oxide layer when the temperature is low during the high temperature heat treatment as in Comparative Example 4 or when the temperature rising rate is low as in Comparative Example 5.

In particular, as in Comparative Example 6, when the conventional method of directly forming the metal bond bonding layer is used, the surface roughness of the thermal barrier coating layer is very low. As a result, the metal bond bonding layer exists as an intermediate layer It can be seen that there is a great problem such as formation of oxide layer having many pores and deterioration of bonding force with the ceramic layer.

7 is an image showing a surface structure of a metal base material heat-treated at a low oxygen partial pressure according to Example 1 and FIG. 8 is an image showing a cross-sectional appearance of a metal base material heat-treated at a low oxygen partial pressure according to Example 1 .

Referring to FIGS. 7 to 8, it can be seen that, when the surface of the metal base material is subjected to the heat treatment under a low oxygen partial pressure of 10 ^-9 atm, there is no pore observed at atmospheric pressure, It can be seen that a thin and continuous single layer is densely formed. As a result, it can be seen that oxygen invading from the outside can be effectively blocked by the aluminum oxide layer, and the bonding force with the ceramic layer is not lowered. In addition, it can be seen that the surface roughness measured by Example 1 is not much different from the surface roughness measured beforehand at 53 nm (Ra), and a very stable surface reaction is obtained as compared with Comparative Examples 1 to 5 described above.

Also, as in Examples 2 to 4, when the oxygen partial pressure during the surface heat treatment of the metal base material was performed under the conditions of 10 ^-10 atm, 10 ^-11 atm, and 10 ^-12 atm and low-oxygen partial pressure, the surface roughness , It can be seen that a highly stable high temperature oxide layer is formed and the intermediate bond coat layer can be replaced only by heat treatment under a low oxygen partial pressure condition without an external coating.

According to the above measurement results, the method of forming a thermal barrier coating layer according to the present invention can form a stable oxide layer at a high temperature without directly coating metal powder on the surface of the base material by high temperature heat treatment of the metal base material under a low oxygen partial pressure condition It is possible to realize excellent effects such as cost reduction, process time shortening, and lifetime of the equipment life cycle. Moreover, it has superior bonding force than the physical bonding of the metal intermediate bonding layer by the outer coating, It can be seen that there is an effect applicable to an aircraft gas turbine engine and the like.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be limited by the described embodiments, but should be determined by the scope of the appended claims as well as the appended claims.

10: metal base material 20: metal bond coating layer
30: alumina layer 50: ceramic coating layer
100: Thermal barrier coating layer

Claims (9)

Heat-treating the metal base material containing aluminum at a temperature of 1100 to 1150 占 폚 under a vacuum condition of an oxygen partial pressure of 10 ^-9 atm to 10 ^-12 atm to form an alumina layer on the surface of the metal base material; And,
And forming a ceramic coating layer on the surface of the alumina layer.
The method according to claim 1,
Wherein the metal base material is a nickel-based or cobalt-based superalloy for gas turbine components comprising aluminum (Al) in an amount of 5 to 20 wt%.
The method according to claim 1,
Further comprising a pretreatment step before the heat treatment in the vacuum condition.
The method according to claim 1,
Wherein the alumina layer is in contact with the metal preform and no metal bonding layer is formed between the alumina layer and the metal preform.
The method according to claim 1,
Wherein the heat treatment is performed at a temperature ranging from 200 to 400 캜 / min, maintained at a temperature of from 1100 to 1150 캜, and then slowly cooled.
An alumina layer formed on the surface of the metal base material containing aluminum; And
A ceramic coating layer formed on the surface of the alumina layer;
/ RTI >
Wherein the alumina layer has a surface roughness of 30 nm to 60 nm (Ra).
The method according to claim 6,
Wherein the metal base material is a nickel-based or cobalt-based superalloy for gas turbine parts comprising aluminum (Al) in an amount of 5 to 20 wt%.
The method according to claim 6,
Wherein the alumina layer is in contact with the metal preform and no metal bonding layer is present between the alumina layer and the metal preform.
The method according to claim 6,
Wherein the alumina layer has a layer thickness of 0.001 탆 to 1 탆, and the ceramic coating layer has a layer thickness of 200 탆 to 500 탆.

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