EP1318273B1

EP1318273B1 - Turbine blade, manufacturing method of turbine blade, and strip judging method of a thermal barrier coat

Info

Publication number: EP1318273B1
Application number: EP02012119A
Authority: EP
Inventors: Shoju Masaki
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 2001-12-07
Filing date: 2002-05-31
Publication date: 2006-11-29
Anticipated expiration: 2022-05-31
Also published as: CA2385932A1; CA2385932C; DE60216405T2; EP1318273A3; EP1318273A2; DE60216405D1; US20030108424A1; JP2003172102A

Description

BACKGROUND OF THE INVENTION

Technical Field of the Invention

The present invention relates to a turbine blade for use in a turbine engine, and the like, further particularly to a structure of a thermal barrier coat applied to an outer peripheral surface of the turbine blade, a manufacturing method of the turbine blade, and a strip judging method of the thermal barrier coat.

Description of the Related Art

A turbine blade for use in a turbine engine is requested to fulfill a predetermined aerodynamic capability and mechanical capability in a high-temperature gas atmosphere. When the temperature of the turbine blade rises, the mechanical capability of a material drops, and it is therefore necessary to maintain the temperature of the turbine blade lower than a predetermined temperature.
In order to set the temperature of the turbine blade to be lower than a predetermined value, a means has heretofore been taken to dispose a coolant gas port in the outer peripheral surface of the turbine blade and emit a coolant gas onto the outer peripheral surface of the turbine blade through an internal air gap. Moreover, the means includes applying a thermal barrier coat onto the outer peripheral surface of the turbine blade, prevent a high-temperature gas from directly contacting the turbine blade, and prevent the temperature of the material of the turbine blade from rising.
Fig. 1 is a structure diagram of a conventional turbine blade. Fig. 2 is an A-A sectional view of Fig. 1, and Figs. 3B and 3C are sectional detailed diagrams of the conventional turbine blade. The structure of the conventional turbine blade will be described hereinafter with reference to these drawings.
The turbine blade means a turbine rotor blade or a turbine stator blade. Fig. 1 shows an example of the turbine rotor blade. A turbine rotor blade 1 is constituted of a turbine blade 2, blade base portion 3 and blade mounting portion 4.
The turbine blade 2 is a columnar structure which outer peripheral surface has a blade shape, which root portion is fixed to the blade base portion 3, and which tip end is a free end. On the other hand, with the turbine stator blade, the tip end is also fixed to the other base portion of the turbine stator blade. A coolant gas supply port 5 and coolant gas exhaust port 6 are disposed in the blade mounting portion 4, extend through the blade base portion 3 and are connected to an internal air gap of the turbine blade as described later.
As shown in Fig. 2, the turbine blade 2 is constituted of a turbine blade main body 10 and thermal barrier coat 20.
The turbine blade main body 10 is a columnar structure 11 which includes internal air gaps 12 and a plurality of coolant gas ports 13 and has a blade-shaped section.
The internal air gaps 12 are air gaps disposed inside the columnar structure 11 so that a coolant gas passes, the columnar structure is divided into a plurality of chambers, and the chambers are connected to one another. The internal air gap 12 in a tip edge of the turbine blade is connected to the coolant gas supply port 5, and the internal air gap 12 in a rear edge of the turbine blade is connected to the coolant gas exhaust port 6.
The coolant gas ports 13 are densely disposed in a region where the temperature of the outer surface of the turbine blade easily rises. The coolant gas ports 13 are holes disposed in the outer peripheral surface of the columnar structure 11. The coolant gas ports 13 are connected to the internal air gaps 12. Each coolant gas port 13 has a diameter, for example, of 0.4 to 0.5 mm.
As shown in Figs. 3B and 3C, the thermal barrier coat 20 is an insulating layer with which the outer peripheral surface of the turbine blade main body 10 (columnar structure 11) is coated, and is constituted of a topcoat 21, interface 22 and bond coat 23.
The bond coat 23 is a foundation treated layer with which the surface of the turbine blade main body is coated, and examples thereof include oxidation-resistance coatings represented by NiCoCrAlY, PtAl, and the like. The interface 22 is a protective layer between the topcoat 21 and the bond coat 23, and is, for example, Al₂O₃, and the like. The topcoat 21 is a layer forming the outer peripheral surface, and examples thereof include a ceramics coating represented by ZrO₂-7%Y₂O₃, and the like.
For example, the thickness of the topcoat 21 is in a range of 100 to 300 µm, the interface 22 has a thickness of 1 µm, and the bond coat 23 has a thickness of 100 µm.
The function of the conventional turbine blade will next be described.
The turbine rotor blade 1 is attached to a turbine disc. When a turbine engine steadily runs, a high-temperature gas flows around the turbine blade, and the turbine disc receives an aerodynamic force and rotates.
The coolant gas is supplied to the coolant gas supply port 5 via the turbine disc. The coolant gas enters the internal air gaps 12 from the coolant gas supply port 5 via the blade mounting portion 4 and blade base portion 3. A part of the coolant gas is blowed out to the outer surface of the turbine blade 2 through the coolant gas ports 13. The remaining coolant gas flows outwards via the coolant gas exhaust port 6 through a plurality of chambers, blade mounting portion 4, and blade base portion 3.
The coolant gas is blowed out onto the outer periphery of the turbine blade flows along the surface of the turbine blade, and prevents the ambient high-temperature gas from directly contacting the turbine blade. As shown in Fig. 3B, the outer periphery of the turbine blade is coated with the thermal barrier coat 20, and a heat of high-temperature gas is prevented from being directly conducted to the turbine blade main body.
According to the above-described function, since the heat of the ambient high-temperature gas does not easily enter the turbine blade main body, the material can be prevented from having a high temperature, and the mechanical strength can be maintained.
With use of the above-described turbine blade, when the turbine engine is continuously run, oxygen molecules of the high-temperature gas permeate the topcoat 21, and aluminum oxide is separated out in the interface 22. It is empirically known that the layer thickness of the interface 22 increases and grows to be about 10 µm, and the topcoat 21 is stripped as shown in Fig. 3C.
The turbine blade having caused the above-described phenomenon has heretofore been changed in a periodic inspection.
Moreover, when the topcoat 21 is stripped, a heat energy of high-temperature gas enters the turbine blade main body 10 via a stripped portion, and the temperature of the turbine blade main body rises to be more than a desired temperature. Therefore, the temperature of the high-temperature gas has heretofore been set to be relatively low during the run.
For example, if the topcoat 21 is not stripped, the turbine blade can be run at 1300°C. For this blade, in consideration of the presence of the strip of the topcoat, the temperature of the high-temperature gas is lowered to 1000°C, and the engine is run. Therefore, there is a problem that the efficiency of the turbine engine cannot be raised further in the present situation.
Moreover, there is a problem that the strip of the topcoat can be found only by a visual check according to the periodic inspection. US-A-6039537 discloses a prior art blade. EP-A-843026 and EP-A-510740 disclose manufacturing methods and strip judging methods of the prior art.

SUMMARY OF THE INVENTION

The present invention has been developed in consideration of the above-described problem, and an object thereof is to provide a turbine blade which can be run by raising a temperature of a high-temperature gas than is possible today, a manufacturing method of the turbine blade, and a strip judging method of a thermal barrier coat.
To achieve the above-described object, according to the present invention, there is provided a turbine blade (2) which outer peripheral surface has a blade shape according to claim 1.
According to the constitution of the present invention, the turbine blade main body (10) has a columnar structure with a blade-shaped section including the internal air gap (12) and the plurality of coolant gas ports (13), the outer peripheral surface of the turbine blade main body is coated with the thermal barrier coat (20) as the insulating layer, and the thermal barrier coat fills in some of the coolant gas ports. Therefore, the coolant gas is blowed out from the coolant gas ports via the internal air gap 12 to cool the turbine blade main body during a usual run. When the thermal barrier coat is stripped, the coolant gas is also blowed out from the coolant gas ports of the stripped portion, the turbine blade is cooled with more coolant gas than during the usual run, and the temperature of the turbine blade can be prevented from rising.
Furthermore, in the turbine blade according to the present invention, the thermal barrier coat (20) fills in the coolant gas ports the number of which exceeds 20% of the total number of coolant gas ports (13).
According to the constitution of the present invention, the thermal barrier coat (20) fills in the coolant gas ports the number of which exceeds 20% of the total number of coolant gas ports (13). Therefore, when a part of the thermal barrier coat is stripped, the number of coolant gas ports of the stripped portion increases, the turbine blade is cooled with the coolant gas having an amount increased by about over 20%, and the temperature of the turbine blade can be prevented from rising.
Moreover, to achieve the above-described object, according to the present invention, there is provided a manufacturing method of a turbine blade which outer peripheral surface has a blade shape, according to claim 4.
According to the method of the present invention, the turbine blade main body preparing step (A) comprises: preparing the turbine blade main body (10) with the blade-shaped section having the internal air gap (12) and the plurality of coolant gas ports (13). The sealing step (B) comprises: filling the sealer into at least some of the coolant gas ports. The coating step (C) after the sealing step comprises: disposing the insulating layer on the outer surface of the turbine blade main body. Therefore, the filled sealer prevents the insulating material from being embedded in the coolant gas ports, and the outer surface of the turbine blade main body is coated with the insulating layer. The outer surface of the columnar structure with the blade-shaped section having the internal air gap and the plurality of coolant gas ports is coated with the thermal barrier coat as the insulating layer, and the thermal barrier coat fills in at least some of the coolant gas ports. This turbine blade can be manufactured.
Furthermore, in the manufacturing method of the turbine blade according to the present invention, the sealing step (B) comprises: filling the sealer into the coolant gas ports the number of which exceeds 20% of the total number of the coolant gas ports.
According to the constitution of the present invention, in the sealing step (B), the sealer is filled into the coolant gas ports the number of which exceeds 20% of the total number of the coolant gas ports. Therefore, a turbine blade (2) can be manufactured in which the outer surface of the columnar structure with the blade-shaped section including the internal air gap and the plurality of coolant gas ports is coated with the thermal barrier coat as the insulating layer, and the thermal barrier coat (20) fills in the number over 20% of the total number of the coolant gas ports.
Additionally, according to the present invention, there is provided a manufacturing method of a turbine blade, comprising: a sealer removing step (D) for removing the sealer after the coating step (C).
According to the constitution of the present invention, in the sealer removing step (D) after the coating step (C), the sealer is removed. Therefore, the outer surface of the columnar structure with the blade-shaped section including the internal air gap and the plurality of coolant gas ports is coated with the thermal barrier coat as the insulating layer, and nothing is filled in the coolant gas ports closed by the thermal barrier coat. When the thermal barrier coat is stripped, the coolant gas is quickly blowed out even from the coolant gas ports of the stripped portion, the turbine blade is cooled with more coolant gas than during the usual run, and the temperature of the turbine blade can be prevented from rising. The turbine blade constituted as described above can be manufactured.
Moreover, to achieve the object, according to the present invention, there is provided a strip judging method of a thermal barrier coat according to claim 7.
According to the constitution of the present invention, the turbine using the turbine blade (2) is prepared, the consumption of the coolant gas supplied to the turbine blade is detected, and the presence/absence of the strip of the thermal barrier coat is judged by the fluctuation of the consumption. Therefore, when the strip of the thermal barrier coat occurs during the run of the turbine, the consumption of the coolant gas increases, the presence of the strip of the thermal barrier coat can be known by detecting the increase and, for example, a means for preventing an abnormal temperature rise of the turbine can quickly be taken.
Other objects and advantageous characteristics of the present invention will be apparent from the following description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a structure diagram of a conventional turbine blade.
Fig. 2 is a sectional view of the conventional turbine blade.
Figs. 3B and 3C are sectional detailed diagrams of the conventional turbine blade.
Fig. 4 is a structure diagram of an embodiment of the present invention.
Fig. 5 is a sectional view of the embodiment of the present invention.
Figs. 6B and 6C are sectional detailed diagrams of the embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment according to the present invention will now be described with reference to the drawings. Additionally, like reference numerals denote like or corresponding parts throughout the drawings to omit tautological explanation.
Fig. 4 is a structure diagram of an embodiment of the present invention. Moreover, Fig. 5 is an A-A sectional view, and Figs. 6B and 6C are sectional detailed diagrams of a turbine blade according to the present invention. The structure of the turbine blade according to the present invention will be described with reference to the drawings.
The turbine blade means a turbine rotor blade or a turbine stator blade. Fig. 4 shows an example of the turbine rotor blade. A turbine rotor blade 1 is constituted of a turbine blade 2, blade base portion 3 and blade mounting portion 4.
The turbine blade 2 is a columnar structure which outer peripheral surface has a blade shape, which root portion is fixed to the blade base portion 3, and which tip end is a free end. On the other hand, with the turbine stator blade, the tip end is also fixed to the other base portion of the turbine stator blade. A coolant gas supply port 5 and coolant gas exhaust port 6 are disposed in the blade mounting portion 4, extend through the blade base portion 3 and are connected to an internal air gap described later of the turbine blade.
As shown in Fig. 5, the turbine blade 2 is constituted of a turbine blade main body 10 and thermal barrier coat 20.
The turbine blade main body 10 is a columnar structure 11 which includes internal air gaps 12 and a plurality of coolant gas ports 13 and which has a blade-shaped section.
The internal air gaps 12 are air gaps disposed inside the columnar structure 11 so that a coolant gas passes, the columnar structure is divided into a plurality of chambers, and the chambers are connected to one another. The internal air gap 12 in a tip edge of the turbine blade is connected to the coolant gas supply port 5, and the internal air gap 12 in a rear edge of the turbine blade is connected to the coolant gas exhaust port 6.
The coolant gas ports 13 are holes disposed in an outer surface of the columnar structure 11. The coolant gas ports 13 are connected to the internal air gaps 12. Each coolant gas port 13 has a diameter, for example, of 0.4 to 0.5 mm.
Some of the coolant gas ports 13 are coated with a topcoat described later. Here, for the convenience of the description, particularly these coolant gas ports 13 will hereinafter be referred to as fireplug ports 14. The coolant gas ports 13 are disposed at equal intervals in a portion which needs to be cooled.
The number of fireplug ports 14 is preferably not less than 20% of the total number of the coolant gas ports 13. The fireplug ports 14 are preferably equally disposed in the plurality of coolant gas ports 13.
The fireplug ports 14 are loaded with a sealer 15. The material of the sealer can be changed with the temperature in an applying step of the topcoat described later. Examples of the sealer include resins such as epoxy resin, PEEK resin, and silicon rubber, simplex compounds such as CaO, AlF₃, NaAlF₆, AlPO₄, and SiO₂, and mixtures. For example, a mixture of AlPO₄ and SiO₂ can be used.
Alternatively, the sealer 15 may be removed beforehand, and nothing may be filled in the fireplug ports 14.
The thermal barrier coat 20 is an insulating layer with which the outer peripheral surface of the turbine blade main body is coated, and is constituted of a topcoat 21, interface 22 and bond coat 23.
The bond coat 23 is a foundation treated layer with which the surface of the turbine blade main body is coated, and examples thereof include oxidation-resistance coatings represented by NiCoCrAlY, PtAl, and the like. The interface 22 is a protective layer between the topcoat 21 and the bond coat 23, and is, for example, Al₂O₃, and the like. The topcoat 21 is a layer which forms the outer peripheral surface, and examples thereof include a ceramics coating represented by ZrO₂-7%Y₂O₃, and the like.
For example, the thickness of the topcoat 21 is in a range of 100 to 300 µm, the interface 22 has a thickness of 1 µm, and the bond coat 23 has a thickness of 100 µm.
The function of the turbine blade according to the embodiment of the present invention will next be described.
The turbine rotor blade 1 is attached to a turbine disc. When a turbine engine steadily runs, a high-temperature gas flows around the turbine blade, and the turbine disc receives an aerodynamic force and rotates.
The coolant gas is supplied to the coolant gas supply port 5 via the turbine disc. The coolant gas enters the internal air gaps from the coolant gas supply port 5 via the blade mounting portion 4 and blade base portion 3. A part of the coolant gas is blowed out to the outer surface of the turbine blade 2 through the coolant gas ports 13 excluding the fireplug ports 14. The remaining coolant gas flows outwards via the coolant gas exhaust port 6 through a plurality of chambers, blade mounting portion 4, and blade base portion 3.
The coolant gas blowed out onto the outer periphery of the turbine blade flows along the surface of the turbine blade, and prevents the ambient high-temperature gas from directly contacting the turbine blade. As shown in Fig. 6B, the outer periphery of the turbine blade is coated with the thermal barrier coat 20, and a heat of high-temperature gas is prevented from being directly conducted to the turbine blade main body.
When the topcoat 21 is stripped from a part of the region, the fireplug ports 14 in the region are exposed. The sealer 15 is pushed outwards by the pressure of the coolant gas of the internal air gap, and the coolant gas is blowed out from the fireplug ports 14. The coolant gas flows along the outer surface of the turbine blade main body from which the topcoat 21 is stripped. As shown in Fig. 6C, the vicinity of the region from which the topcoat 21 is stripped is covered with the coolant gas blowed out from the ambient coolant gas ports 13 and the coolant gas blowed out from the fireplug ports, and the high-temperature gas is prevented from contacting the surface of the turbine blade main body.
According to the above-described function, since the heat of ambient high-temperature gas does not easily enter the turbine blade main body, the material can be prevented from a high temperature, and the mechanical strength of the material can be maintained.
A manufacturing method according to the embodiment of the present invention will next be described in order of steps.

(1) Turbine Blade Main Body Preparing Step (A):

The turbine blade main body is prepared including the internal air gap 12 disposed inside so that the coolant gas passes and the plurality of coolant gas ports 13 which are connected to the internal air gap 12 and disposed in the outer peripheral surface. The structure of the turbine blade main body is the same as described above, and therefore the description thereof is omitted. Some of the coolant gas ports 13 constitute the fireplug ports 14.

(2) Sealing Step (B):

The sealer is filled in at least some of the plurality of coolant gas ports 13. Preferably, the sealer is filled in the coolant gas ports 13 the number of which exceeds 20% of the total number of coolant gas ports 13. The material of the sealer is selected in accordance with a treatment temperature of a coating step as a post-step. Additionally, a heat-resistance temperature of the material of the sealer needs to be higher than an atmosphere temperature in which the turbine blade 2 is disposed in the coating step as the post-step.
For example, when the coating is performed by thermal spraying, the temperature of the turbine blade main body 10 is relatively low, and therefore the material of the sealer is selected from the resins such as the epoxy resin, PEEK resin, and silicon rubber.
Moreover, for example, when the coating is performed by vapor deposition, the turbine blade main body 10 is at a high temperature. Therefore, the material of the sealer is selected from the simplex compounds such as CaO, AlF₃, Na₃AlF₆, AlPO₄, and SiO₂, and mixtures of these compounds. For example, a mixture of AlPO₄ and SiO₂ may be selected.

(3) Coating Step (C):

This is a step performed after the sealing step, and the insulating layer is disposed on the outer surface of the turbine blade main body. Depending on the circumstances, the coolant gas ports 13 excluding the fireplug ports 14 are masked.
First, the surface of the turbine blade main body 10 is coated with the bond coat. Subsequently, the surface of the bond coat is coated with the interface. Finally, the surface of the interface is coated with the topcoat.

(4) Sealer Removing Step (D):

This is a step performed after the coating step (C), and the sealer is removed. For example, the turbine blade is immersed in water, and the sealer is molten out. Depending on the circumstances, without performing the present step, the sealer may be left in the turbine blade main body.
A strip judging method of the thermal barrier coat using the embodiment of the present invention will next be described.

(1) Turbine Preparing Step (A):

The turbine using the turbine blade is prepared.

(2) Coolant Gas Consumption Detecting Step:

Consumption of the coolant gas supplied to the turbine blade is detected.

(3) Judging Step of Presence/Absence of Strip of Thermal Barrier Coat:

The presence/absence of the strip of the thermal barrier coat is judged by the fluctuation of the consumption of the coolant gas.
With the use of the turbine blade of the present invention, even when the topcoat is stripped, the temperature of the material of the turbine blade does not rise, and a predetermined mechanical capability can be maintained. Moreover, even with the strip of the topcoat, there is not a possibility that the temperature of the material of the turbine blade rises. Therefore, the gas temperature of the turbine can be raised, and turbine efficiency is enhanced. Furthermore, the consumption of the coolant gas blowed out from the coolant gas ports is small, until the topcoat is stripped. Therefore, the whole mechanical efficiency of the turbine is enhanced.
Moreover, when the manufacturing method of the turbine blade is used according to the present invention, conventional manufacturing apparatuses of turbine blades can be used to simply manufacture the turbine blade of the present invention.
Furthermore, when the strip judging method of the thermal barrier coat according to the present invention is used, the strip of the topcoat can be confirmed even during the run of the turbine, and the turbine can appropriately be run. Moreover, when the topcoat is stripped, the turbine blade can quickly be changed.
As described above, the turbine blade of the present invention has the following effects.
During the normal run, the coolant gas is blowed out from the coolant gas ports via the internal air gap to cool the turbine blade main body. When the thermal barrier coat is stripped, the coolant gas is blowed out even from the coolant gas ports of the strip portion, the turbine blade is cooled with more coolant gas than during the usual run, and the temperature of the turbine blade can be prevented from rising.
Moreover, when a part of the thermal barrier coat is stripped, the number of coolant gas ports of the stripped portion increases, the turbine blade is cooled with the coolant gas of the amount increased by over about 20%, and the temperature of the turbine blade can be prevented from rising.
Furthermore, the turbine blade can be manufactured in which the filled sealer prevents the insulating material from being buried in the coolant gas ports, the outer surface of the turbine blade main body can be coated with the insulating layer, the outer surface of the columnar structure with the blade-shaped section having the internal air gap and the plurality of coolant gas ports is coated with the thermal barrier coat as the insulating layer, and the thermal barrier coat fills in at least some of the coolant gas ports.
Moreover, the sealer is filled in the coolant gas ports the number of which is 20% or more of the total number of coolant gas ports. Therefore, the turbine blade can be manufactured in which the outer surface of the columnar structure with the blade-shaped section having the internal air gap and the plurality of coolant gas ports is coated with the thermal barrier coat as the insulating layer, and the thermal barrier coat fills in the number of coolant gas ports exceeding 20% of the total number of coolant gas ports.
Furthermore, nothing is filled in the coolant gas ports closed by the thermal barrier coat. Therefore, when the thermal barrier coat is stripped, the coolant gas is quickly blowed out even from the coolant gas ports in the stripped portion, the turbine blade is cooled with more coolant gas than during the usual run, and the temperature of the turbine blade can be prevented from rising. Such turbine blade can be manufactured.
Additionally, the turbine using the turbine blade is prepared, the consumption of the coolant gas supplied to the turbine blade is detected, the presence/absence of the strip of the thermal barrier coat is judged by the fluctuation of the consumption, the strip of the thermal barrier coat can be known during the run of the turbine and, for example, a means for preventing the abnormal temperature rise of the turbine can quickly be taken.
Therefore, there can be provided the turbine blade which can be run by raising the temperature of the high-temperature gas, the manufacturing method of the turbine blade, and the method of judging the strip of the thermal barrier coat.
Moreover, the present invention has been described in terms of some preferred embodiments, but it would be understood that the rights scope included in the present invention is not limited to these embodiments. Contrarily, the rights scope of the present invention includes all improvements, modifications and equivalents included in the appended claims.

Claims

A turbine blade (2) which outer peripheral surface has a blade shape, comprising:
a turbine blade main body (10) with a blade-shaped section, wherein the blade-shaped section includes an internal air gap (12) disposed inside for passing coolant gas and a plurality of coolant gas ports (13) disposed in the outer peripheral surface for being connectable to the internal air gap (12), and a thermal barrier coat (20) as an insulating layer with which the outer peripheral surface of the turbine blade main body (10) is coated, characterized in that the thermal barrier coat (20) comprises a bond coat (23), an interface (22), and a topcoat (21), wherein the topcoat (21) covers some of the coolant gas ports (13).
A turbine blade according to claim 1, characterized in that the topcoat (21) covers at least 20% of a total number of coolant gas ports (13).
A turbine blade according to claim 1 or 2, characterized in that the interface (22) is a layer between the topcoat (21) and the bond coat (23), and consists of aluminum oxide.
A manufacturing method of a turbine blade (2) which outer peripheral surface has a blade shape, the method comprising:
- a turbine blade main body preparing step (A) for preparing a turbine blade main body (10) with a blade-shaped section, which includes an internal air gap (12) disposed inside for passing a coolant gas and a plurality of coolant gas ports (13) disposed in the outer peripheral surface for being connectable to the internal air gap (12);

- a sealing step (B) for filling a sealer (15) into at least some of said coolant gas ports (13); and
characterized by
- a coating step (C) for disposing a bond coat (23) and an interface (22), and a topcoat (21) on an outer surface of the turbine blade main body (10) after the sealing step, wherein the topcoat (21) covers the sealed coolant gas ports (13).
A manufacturing method according to claim 4, wherein said sealing step (B) comprises:
a step for filling the sealer (15) into at least 20% of a total number of said coolant gas ports (13).
A manufacturing method according to claim 4 or 5, further comprising: a sealer removing step (D) of removing the sealer (15) after said coating step (C).
A strip judging method of a thermal barrier coat, comprising steps for:
- preparing a turbine using a turbine blade (2) according to one of the claims 1 to 3;

- detecting consumption of a coolant gas supplied to the turbine blade (2); and

- judging a presence of a strip of said thermal barrier coat (20) by a fluctuation of said consumption.