JP2018172731A - Thermal barrier coating, turbine blade, and production method of thermal barrier coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of a porous layer and a substrate by suppressing crack of a coating formed on the porous layer constituting a thermal barrier coating.SOLUTION: A thermal barrier coating includes: a porous layer containing cubic crystal or tetragonal zirconia, and a first zirconia stabilization element for stabilizing the cubic crystal or tetragonal zirconia, and formed on a substrate; a dense layer containing the cubic crystal or tetragonal zirconia, and a second zirconia stabilization element for stabilizing the cubic crystal or tetragonal zirconia, formed on the porous layer, and denser than the porous layer; and particles dispersed in the dense layer.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to thermal barrier coatings, turbine blades, and methods of manufacturing thermal barrier coatings.

  In the field of industrial gas turbines, thermal barrier coating (TBC) is known that can reduce the heat load on the heat-resistant member without changing the shape of the blades or the cooling structure provided on the blades. Yes.

For example, Patent Document 1 discloses a ceramic layer made of zirconia (ZrO ₂ ) to which Yb ₂ O ₃ is added as a stabilizer, and a corrosion component penetration preventing layer that is provided on the ceramic layer and is made of the same material as the ceramic layer. , A thermal barrier coating is disclosed.
Patent Document 2 discloses a thermal barrier coating in which an environmental shielding layer made of silica is formed on a ceramic layer made of zirconia. Patent Document 2 describes forming an environmental shielding layer by a sol-gel method using an alcohol solution of a metal alkoxide.

JP 2003-160852 A JP 2012-137073 A

Here, it is conceivable that the corrosion component penetration preventing layer in the thermal barrier coating described in Patent Document 1 is formed by a sol-gel method or a thermal spraying method described in Patent Document 2.
However, the corrosion component permeation preventive layer is easily cracked during film formation, and it is not easy to obtain a highly reliable corrosive component permeation preventive layer. For example, when the corrosion component permeation preventive layer is formed of a ceramic having high heat resistance (for example, zirconia to which Yb ₂ O ₃ is added as a stabilizer as in Patent Document 1), the corrosive component permeation preventive layer is sprayed. Therefore, a very high process temperature condition is required to form a film, and the risk of cracking of the corrosion component penetration preventing layer during spraying increases. Alternatively, when the corrosive component permeation preventive layer is formed by the sol-gel method described in Patent Document 2, there is a possibility that the corrosive component permeation preventive layer is cracked due to thermal stress generated under the temperature conditions during operation of the gas turbine. is there.
When a crack occurs in the corrosion component penetration prevention layer, the corrosion component penetrates into the ceramic layer and the base material from the cracked part, so the corrosion component penetration prevention layer is formed while preventing the corrosion component penetration prevention layer from cracking. It is hoped to do.

  In view of the above circumstances, at least one embodiment of the present invention improves the durability of the porous layer and the substrate by suppressing cracking of the coating film formed on the porous layer constituting the thermal barrier coating. For the purpose.

(1) The thermal barrier coating according to at least one embodiment of the present invention is:
A porous layer formed on a substrate, comprising cubic or tetragonal zirconia and a first zirconia stabilizing element that stabilizes cubic or tetragonal zirconia;
A cubic layer or tetragonal zirconia and a second zirconia stabilizing element that stabilizes cubic or tetragonal zirconia, formed on the porous layer, and a dense layer denser than the porous layer; ,
And particles dispersed in the dense layer.

Since the thermal barrier coating having the configuration (1) includes particles dispersed in the dense layer, the ratio of components that contract during firing of the dense layer (components other than particles) can be reduced, and the shrinkage force can be reduced. Thus, cracking of the dense layer can be suppressed. Moreover, since the particles contained in the dense layer try to prevent the shrinkage of the dense layer during firing (that is, the shrinkage of the dense layer is suppressed by the drag caused by the particles), the cracking of the dense layer can be suppressed. Thereby, durability of a porous layer and a base material can be improved.
Further, by dispersing particles in the dense layer, the dense layer can be made thicker, the effect of preventing penetration of corrosive components can be improved, and the strength of the dense layer can be improved. The durability of can be improved.

(2) In some embodiments, in the configuration of (1), the particles are formed of stabilized zirconia including a third zirconia stabilizing element that stabilizes cubic or tetragonal zirconia.

  According to the configuration of (2) above, since the particles are formed of stabilized zirconia, the linear expansion coefficient of the particles and the linear expansion coefficient of the porous layer or the dense layer containing cubic or tetragonal zirconia Therefore, a thermal barrier coating excellent in heat cycle durability can be provided.

(3) In some embodiments, in the configuration of (2), the first zirconia stabilizing element, the second zirconia stabilizing element, and the third zirconia stabilizing element are magnesium, an alkaline earth metal element, Or a rare earth element.

  According to the configuration of (3) above, the first zirconia stabilizing element, the second zirconia stabilizing element, and the third zirconia stabilizing element are any of magnesium, an alkaline earth metal element, and a rare earth element. Therefore, even if the temperature of the porous layer, the dense layer, and the particles changes, the phase transition of cubic or tetragonal zirconia is suppressed. Thereby, durability of a porous layer and a dense layer can be improved.

(4) In some embodiments, in any one of the configurations (1) to (3), the particles include at least two types of particles having different particle sizes.

According to the configuration of (4) above, since the small particle size particles are arranged in the gaps in which the large particle size particles are arranged, the packing density of the particles in the dense layer is increased. Therefore, the shrinkage force at the time of firing the dense layer can be effectively reduced by the particles packed in the dense layer with high density, and cracking of the dense layer can be appropriately suppressed.
Moreover, since the intensity | strength of a dense layer improves because the packing density of the particle | grains in a dense layer increases, durability of a porous layer and a base material can be improved.

(5) A turbine blade according to at least one embodiment of the present invention includes:
A turbine blade body,
A thermal barrier coating of any one of (1) to (4) provided to cover the surface of the turbine blade body.

  According to the configuration of (5), since the cracking of the dense layer can be suppressed as described above, the durability of the porous layer and the substrate can be improved. Thereby, durability of a turbine blade can be improved.

(6) A method for producing a thermal barrier coating according to at least one embodiment of the present invention comprises:
The base material in which a porous layer containing cubic or tetragonal zirconia and a first zirconia stabilizing element for stabilizing cubic or tetragonal zirconia is formed on at least a part of the surface of the base material. For the porous layer,
Applying a liquid comprising a zirconium alkoxide compound and a second zirconia stabilizing element that stabilizes cubic or tetragonal zirconia;
Heating the base material coated with the liquid to form a coating on the porous layer.

  According to the method of (6) above, a liquid containing an alkoxide compound of zirconium and a second zirconia stabilizing element is applied to the porous layer formed on the base material, and the base material to which the liquid is applied is applied. A zirconia film can be formed on the porous layer by heating. In this method, it is possible to form a film under a process temperature condition sufficiently lower than that in the case where the zirconia film is formed by thermal spraying, and therefore it is possible to suppress cracking of the zirconia film. Thereby, durability of a porous layer and a base material can be improved.

(7) In some embodiments, in the method of (6), a porous layer containing cubic or tetragonal zirconia and a first zirconia stabilizing element that stabilizes cubic or tetragonal zirconia. Is further formed on at least a part of the surface of the substrate.

  According to the above method (7), the porous layer containing cubic or tetragonal zirconia and the first zirconia stabilizing element that stabilizes cubic or tetragonal zirconia is provided on at least one surface of the substrate. By further including the step of forming the part, the porous layer can be formed on the assumption that the coating film is generated on the porous layer. Thereby, for example, on the premise that the coating film has a role of suppressing the penetration of corrosive substances, the porous layer can be formed to have a porosity and a thickness that can ensure the required thermal conductivity. Therefore, the durability of the porous layer and the substrate can be improved.

(8) In some embodiments, in the method of (6) or (7), the alkoxide compound includes at least one of ethoxide, propoxide, or butoxide.

  According to the method of (8), since the alkoxide compound contains at least one of ethoxide, propoxide, or butoxide, a zirconia film can be formed from the liquid at a temperature sufficiently lower than the melting point of zirconia, The manufacturing cost of the thermal barrier coating can be suppressed. In other words, since the heating temperature when heating the substrate coated with the above liquid can be kept low, the energy cost required for heating and the cost of the apparatus for heating can be suppressed, and the manufacturing cost of the thermal barrier coating. Can be suppressed. Moreover, when the heat processing with respect to a base material or a porous layer is required, since this heat processing and the heat processing for producing | generating the film of a zirconia can be combined, the manufacturing cost of a thermal barrier coating can further be suppressed.

(9) In some embodiments, in the method according to any one of (6) to (8), the liquid further includes a dispersion stabilizer for the alkoxide compound.

  According to the method (9) above, the liquid contains the dispersion stabilizer of the alkoxide compound, so that the liquid quality of the liquid is stable, and the alkoxide compound changes such as decomposition and aggregation over time. Therefore, handling of the above liquid becomes easy, and the manufacture of the thermal barrier coating becomes easy. Further, since the liquid quality of the above liquid is stabilized, the quality of the produced zirconia film is also stabilized, and the performance of the thermal barrier coating is stabilized.

(10) In some embodiments, in the method of (9), the dispersion stabilizer includes an alcohol that is at least one of methanol or ethanol.

  According to the method of (10) above, the liquid containing the alkoxide compound can be appropriately stabilized by using a lower alcohol such as methanol or ethanol as the dispersion stabilizer.

(11) In some embodiments, in the method of (10), the total molar ratio of the alcohol in the liquid is 5% or more.

  According to the above method (11), by setting the total molar ratio of alcohols in the liquid to 5% or more, the liquid quality of the liquid becomes more stable. The manufacture of the thermal coating is easier. In addition, since the liquid quality of the liquid is more stable, the quality of the produced zirconia film is more stable, and the performance of the thermal barrier coating is more stable.

(12) In some embodiments, in any of the methods (9) to (11), the dispersion stabilizer includes an acid.

  According to the method of (12), the liquid quality of the liquid is stabilized by adjusting the hydrogen ion concentration of the liquid with the acid, so that the liquid can be easily handled, and the thermal barrier coating Manufacturing is easy. Further, since the liquid quality of the above liquid is stabilized, the quality of the produced zirconia film is also stabilized, and the performance of the thermal barrier coating is stabilized.

(13) In some embodiments, in the method of (12), a molar ratio of the acid in the liquid is 1% or more.

  According to the method of (13), since the liquid quality of the above liquid becomes more stable by setting the molar ratio of the acid in the liquid to 1% or more, the above liquid becomes easier to handle and the thermal barrier coating. Is easier to manufacture. In addition, since the liquid quality of the liquid is more stable, the quality of the produced zirconia film is more stable, and the performance of the thermal barrier coating is more stable.

(14) In some embodiments, in any one of the methods (6) to (13), the first zirconia stabilizing element and the second zirconia stabilizing element are magnesium, an alkaline earth metal element, Or a rare earth element.

  According to the method of (14) above, since the first zirconia stabilizing element and the second zirconia stabilizing element contain any of magnesium, an alkaline earth metal element, and a rare earth element, the temperature of the porous layer and the coating changes. Even so, the phase transition of cubic or tetragonal zirconia is suppressed. Thereby, durability of a porous layer and a film can be improved.

(15) In some embodiments, in any one of the methods (6) to (14), the total molar ratio of the second zirconia stabilizing element in the liquid is based on zirconium contained in the liquid. And 5% or more.

  According to the method of (15) above, by setting the amount of the second zirconia stabilizing element to be in the above range, a thermal barrier coating having more excellent crystal stability and heat cycle durability can be obtained. .

(16) In some embodiments, in any of the above methods (6) to (15),
The liquid includes particles,
The base material coated with the liquid is heated to produce the coating film containing the particles on the porous layer.

  According to the above method (16), since particles are contained in the coating, the ratio of components that contract during firing of the coating (components other than particles) can be reduced, and the shrinkage force can be reduced to prevent cracking of the coating. Can be suppressed. In addition, since the particles contained in the coating tend to hinder the shrinkage of the coating during firing (that is, the shrinkage of the coating is suppressed by the drag caused by the particles), the cracking of the coating can be suppressed. Thereby, since the crack of a film can be suppressed, durability of a porous layer and a base material can be improved.

(17) In some embodiments, in the method of (16), the particles are formed of stabilized zirconia containing a third zirconia stabilizing element that stabilizes cubic or tetragonal zirconia.

  According to the method of (17), since the particles are formed of stabilized zirconia, the linear expansion coefficient of the particles and the linear expansion coefficient of the porous layer or coating containing cubic or tetragonal zirconia are calculated. Therefore, it is possible to provide a thermal barrier coating excellent in heat cycle durability.

  According to at least one embodiment of the present invention, it is possible to improve the durability of the porous layer and the substrate by suppressing cracking of the coating film formed on the porous layer constituting the thermal barrier coating.

It is a schematic diagram of the cross section of a turbine blade provided with the thermal barrier coating which concerns on one Embodiment. It is a schematic diagram of the cross section of a turbine blade provided with the thermal barrier coating which concerns on one Embodiment. It is a schematic diagram of the cross section of a turbine blade provided with the thermal barrier coating which concerns on one Embodiment. It is typical sectional drawing which expanded the vicinity of the dense layer in embodiment shown in FIG. It is typical sectional drawing to which the vicinity of the dense layer in embodiment shown in FIG. 3 was expanded. It is explanatory drawing which arranges and shows the manufacturing process of the thermal barrier coating which concerns on some embodiment in the order of the process. It is a figure explaining the preparation process of the coating liquid which concerns on some embodiment. It is the typical sectional view which expanded the neighborhood of the porous layer with which slurry was applied. It is a perspective view which shows the structural example of the gas turbine rotor blade which can apply the thermal barrier coating which concerns on some embodiment. It is a perspective view which shows the structural example of the gas turbine stationary blade which can apply the thermal barrier coating which concerns on some embodiment. It is a figure showing typically the partial section structure of the gas turbine concerning one embodiment.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

(Thermal barrier coating)
1 to 3 are schematic views of a cross section of a turbine blade including a thermal barrier coating according to an embodiment. In some embodiments, a metal bonding layer 12 and a ceramic layer 13 are sequentially formed as a thermal barrier coating on a heat-resistant substrate 11 such as a moving blade or a stationary blade of a turbine. That is, as shown in FIGS. 1 to 3, in some embodiments, a thermal barrier coating (TBC) layer 10 includes a metal bonding layer 12 and a ceramic layer 13.
The metal bonding layer 12 is composed of an MCrAlY alloy (M represents a metal element such as Ni, Co, Fe, or a combination of two or more of these).

In some embodiments shown in FIGS. 1 to 3, the ceramic layer 13 includes a porous layer 14 and a dense layer 15. The porous layer 14 and the dense layer 15 in some embodiments are each composed of YSZ (yttria-stabilized zirconia), that is, cubic or tetragonal ZrO ₂ containing Y ₂ O ₃ as a stabilizing element.
In some embodiments shown in FIGS. 1 to 3, the porous layer 14 has a porous structure including many pores 16. Here, “contains a lot” means that the porosity (volume%) is higher than that of the dense layer 15. The porosity and thickness of the porous layer 14 are appropriately set according to the required thermal conductivity.

In some embodiments shown in FIGS. 1 to 3, the dense layer 15 has a denser structure than the porous layer 14 and is formed on the porous layer 14. The “dense structure” here specifically refers to suppressing, to some extent, penetration of a corrosive component (corrosive substance) as will be described later into the porous layer 14, the metal bonding layer 12, and the heat-resistant substrate 11. It is a tissue having a porosity that can be obtained.
The porosity and thickness of the dense layer 15 are appropriately determined in consideration of the effect of suppressing the penetration of corrosive substances (hereinafter referred to as the penetration suppression effect), the thermal conductivity required when the ceramic layer 13 is used, and the like. Is set. The thickness of the ceramic layer 13 is not particularly limited, but is 0.1 mm or more and 1 mm or less.

In the embodiment shown in FIGS. 2 and 3, YSZ particles (YSZ particles) 17 are dispersed in the dense layer 15. In the embodiment shown in FIG. 2, as shown in FIG. 4, one type of YSZ particle, that is, YSZ particle 17 a that is one particle group having a certain average diameter is dispersed in the dense layer 15. 4 is a schematic cross-sectional view enlarging the vicinity of the dense layer 15 in the embodiment shown in FIG.
In the embodiment shown in FIG. 3, as shown in FIG. 5, two types of YSZ particles 17 b and 17 c having different particle sizes are dispersed in the dense layer 15. FIG. 5 is a schematic cross-sectional view enlarging the vicinity of the dense layer 15 in the embodiment shown in FIG.
That is, in the embodiment shown in FIG. 3 and FIG. 5, the YSZ particles 17 dispersed in the dense layer 15 have a smaller average diameter than the YSZ particles 17b, which are one particle group having a certain average diameter, and the YSZ particles 17b. YSZ particle 17c which is one particle group. In addition, the average diameter cited as the parameter of the particle group may be, for example, an arithmetic average diameter, or may be a maximum diameter, a central diameter, or the like. The YSZ particles 17 are not limited to a particle group having a particle size distribution such that the particle size distribution has one peak, and may include a particle group having a particle size distribution in which two or more particle size distribution peaks appear. .

The average diameter of the YSZ particles 17a dispersed in the dense layer 15 in the embodiment shown in FIGS. 2 and 4, and the average diameter of the YSZ particles 17b and 17c dispersed in the dense layer 15 in the embodiment shown in FIGS. Is appropriately set according to the thickness of the dense layer 15 and the required thermal conductivity. For example, the average diameters of the YSZ particles 17b and 17c dispersed in the dense layer 15 in the embodiment shown in FIGS. 3 and 5 are about 3 to 5 μm and about 0.5 μm, respectively. That is, the average diameter of the YSZ particles 17c cited as an example is about one-tenth to one-tenth of the average diameter of the YSZ particles 17b cited as an example.
In the dense layer 15 in which the YSZ particles 17b and 17c having such an average diameter are dispersed, as shown in FIG. 5, the YSZ particles 17c in which a plurality of YSZ particles 17c are arranged are efficiently arranged in the gaps. The packing density of the YSZ particles 17 in the dense layer 15 is increased.

  For example, in an industrial gas turbine or the like, it comes into contact with a combustion gas containing a corrosive substance generated by combustion. Therefore, when the corrosive substance comes into contact with the porous layer 14 of the turbine blade, the corrosive substance penetrates into the metal bonding layer 12 and the heat-resistant substrate 11 through the pores 16 included in the porous layer 14 and the metal bonding layer. 12 and the heat-resistant substrate 11 may be corroded. That is, when a plurality of pores 16 included in the porous layer 14 are continuous to form continuous pores, or when cracks or the like exist in the porous layer 14, the corrosive substance is transferred to the metal bonding layer 12 or There is a risk of penetration into the heat-resistant substrate 11.

Therefore, in some of the embodiments described above, a dense layer 15 is provided on the porous layer 14 in order to prevent the corrosive substance from penetrating into the porous layer 14, the metal bonding layer 12, and the heat-resistant substrate 11. ing.
Therefore, in some of the embodiments described above, the dense layer 15 prevents the corrosive substance from penetrating into the porous layer 14, the metal bonding layer 12, and the heat resistant substrate 11. 12. The durability of the heat resistant substrate 11 can be improved. That is, in some embodiments described above, the durability of the TBC layer 10 can be improved, so that the durability of the turbine blade can be improved.

In some embodiments described above, since the surface of the porous layer 14 is covered with the dense layer 15 denser than the porous layer 14, the strength of the porous layer 14 (strength of the ceramic layer 13) is increased. Can be improved. That is, in some embodiments described above, the durability of the TBC layer 10 can be improved, so that the durability of the turbine blade can be improved.
In some embodiments described above, since the dense layer 15 is made of YSZ like the porous layer 14, the linear expansion coefficient of the dense layer 15 and the linear expansion coefficient of the porous layer 14 can be matched, The heat cycle durability of the TBC layer 10 becomes good.

  In some embodiments described above, the YSZ particles 17 are dispersed in the dense layer 15. Thereby, in the manufacturing process of the dense layer 15 to be described later, the ratio of components (components other than particles) that shrink during firing of the dense layer 15 can be reduced, and the shrinkage force can be reduced to suppress cracking of the dense layer 15. . Further, since the YSZ particles 17 included in the dense layer 15 try to prevent the shrinkage of the dense layer 15 during firing (that is, the shrinkage of the dense layer 15 is suppressed by the drag force of the YSZ particles 17). 15 cracks can be suppressed. This makes it difficult for the corrosive substance to penetrate into the dense layer 15, so that the penetration of the corrosive substance into the porous layer 14, the metal bonding layer 12, and the heat resistant substrate 11 can be effectively suppressed. The durability of the metal bonding layer 12 and the heat resistant substrate 11 can be further improved. That is, in some embodiments described above, since the durability of the TBC layer 10 can be further improved, the durability of the turbine blade can be further improved.

  In some embodiments described above, by dispersing the YSZ particles 17 in the dense layer 15, the dense layer 15 can be made thicker and the effect of preventing the penetration of corrosive components is improved. Therefore, the durability of the porous layer 14, the metal bonding layer 12, and the heat resistant substrate 11 can be further improved. That is, in some embodiments described above, since the durability of the TBC layer 10 can be further improved, the durability of the turbine blade can be further improved.

In some embodiments described above, the particles dispersed in the dense layer 15 are YSZ particles 17. The portion of the dense layer 15 other than the YSZ particles 17 and the porous layer 14 are made of YSZ. Therefore, since the portion of the dense layer 15 other than the YSZ particles 17 and the YSZ particles 17 and the porous layer 14 contain Y ₂ O ₃ as a stabilizing element, the phase transition of cubic or tetragonal zirconia even when the temperature changes Is suppressed. Thereby, the durability of the TBC layer 10 can be improved. Moreover, since the linear expansion coefficient of the YSZ particles 17 and the portions of the dense layer 15 other than the YSZ particles 17 and the linear expansion coefficient of the porous layer 14 can be matched, the heat cycle durability of the TBC layer 10 is improved. .

In one embodiment shown in FIGS. 3 and 5, two types of YSZ particles 17 b and 17 c having different particle diameters are dispersed in the dense layer 15. Thereby, since the YSZ particles 17c having a small particle size are arranged in the gap in which the YSZ particles 17b having a large particle size are arranged, the packing density of the YSZ particles 17 in the dense layer 15 is increased. Therefore, in the manufacturing process of the dense layer 15 to be described later, the shrinkage force at the time of firing the dense layer 15 is effectively reduced by the YSZ particles 17 packed in the dense layer 15 at high density, and cracking of the dense layer 15 is prevented. It can be suppressed appropriately.
Further, since the packing density of the YSZ particles 17 in the dense layer 15 is increased, the strength of the dense layer 15 is improved, so that the durability of the TBC layer 10 can be improved and the durability of the turbine blade can be improved.

(Method of manufacturing thermal barrier coating)
Hereinafter, the manufacturing method of the thermal barrier coating which concerns on some embodiment is demonstrated below with reference to FIG. FIG. 6 is an explanatory view showing the manufacturing process of the thermal barrier coating according to some embodiments in the order of the processes.
The thermal barrier coating manufacturing method according to some embodiments includes a step of forming a metal bonding layer 12 on the heat resistant substrate 11 (metal bonding layer forming step), and a heat resistant substrate 11 on which the metal bonding layer 12 is formed. A step of forming the porous layer 14 on the top (porous layer forming step) and a step of forming the dense layer 15 on the porous layer 14 (dense layer forming step) are provided.

  In the metal bonding layer forming step, a metal bonding layer is formed on the heat-resistant substrate 11 by using a low pressure plasma spraying method (LPPS), an atmospheric plasma spraying method (APS), a high-speed flame spraying (HVOF), etc. 12 is formed.

Next, the porous layer 14 is formed on the heat resistant substrate 11 on which the metal bonding layer 12 is formed.
In the porous layer forming step, the porous layer 14 can be formed by, for example, an atmospheric pressure plasma spraying method or an electron beam physical vapor deposition method using ZrO ₂ —Y ₂ O ₃ powder.
_{Incidentally,} ZrO 2 _-Y 2 _{O 3} powder can be prepared by the following procedure. First, a ZrO ₂ powder and a Y ₂ O ₃ powder having a predetermined addition ratio are prepared, and these powders are mixed with a suitable binder and a dispersant in a ball mill to form a slurry. Next, this is granulated with a spray dryer and dried, and then solidified by diffusion heat treatment to obtain a composite powder of ZrO ₂ —Y ₂ O ₃ . And the porous layer 14 which consists of YSZ can be obtained by spraying this composite powder on the metal bond layer 12. FIG. Moreover, when using an electron beam physical vapor deposition method as the film-forming method of the porous layer 14, the ingot obtained by sintering or electromelting the raw material which has a predetermined composition is used.

Next, the dense layer 15 is formed on the surface side of the porous layer 14.
In the dense layer forming step, a liquid (coating liquid) containing an alkoxide compound of zirconium and a zirconia stabilizing element that stabilizes cubic or tetragonal zirconia is prepared in advance, and this coating liquid is applied to the surface of the porous layer 14. Apply to. And the dense layer 15 is obtained by heat-processing the coating liquid apply | coated to the surface of the porous layer 14. FIG. Hereinafter, the dense layer forming step will be described in detail.

(Preparation of coating solution)
The coating liquid according to some embodiments is prepared, for example, as follows. FIG. 7 is a diagram for explaining a coating liquid preparation process according to some embodiments.
First, a mixture of an aqueous solution of a salt containing a zirconia stabilizing element that stabilizes cubic or tetragonal zirconia and a dispersion stabilizer is prepared. As a salt containing a zirconia stabilizing element (a salt of a zirconia stabilizing element), for example, yttrium nitrate can be used.
In addition, as the salt of the zirconia stabilizing element, an inorganic salt or an organic salt other than nitrate may be used. The zirconia stabilizing element is not limited to yttrium, and may be any of alkaline earth metal elements such as magnesium and calcium, or rare earth elements, and may be two or more of these elements. .
By setting the total molar ratio of the zirconia stabilizing element to zirconium to 5% or more, more excellent crystal stability can be obtained.

  The dispersion stabilizer is a dispersion stabilizer of an alkoxide compound of zirconium described later, and for example, a lower alcohol such as methanol or ethanol can be used. In addition, as the dispersion stabilizer, for example, an acid such as formic acid or acetic acid may be used. As the dispersion stabilizer, only one of the above alcohol and the above acid may be used, or both of them may be used.

  In addition, the liquid quality of a coating liquid becomes more stable because the sum total of the molar ratio of said alcohol in a coating liquid shall be 5% or more. Moreover, the liquid quality of a coating liquid becomes more stable because the molar ratio of said acid in a coating liquid shall be 1% or more.

Next, a mixture of an aqueous solution of a zirconia stabilizing element salt and a dispersion stabilizer and an alkoxide compound of zirconium are mixed to prepare a coating solution. The zirconium alkoxide compound includes at least one of zirconium ethoxide, zirconium propoxide, or zirconium butoxide.
Thus, since the coating solution contains a dispersion stabilizer, a stable dispersion state of the zirconium alkoxide compound is maintained.

  In some embodiments, a slurry is prepared by mixing the coating liquid and the YSZ particles 17 described above.

(Coating solution application)
The coating liquid or slurry prepared as described above is applied to the surface of the porous layer 14 by dipping, brushing, spraying, or the like, for example.

(Heat treatment)
The coating solution or slurry applied to the surface of the porous layer 14 as described above is sintered by heat treatment (firing). As a result, the zirconium alkoxide compound in the coating solution or slurry applied to the surface of the porous layer 14 changes to zirconia, and the zirconia coating, that is, the dense layer 15 described above is obtained.
An example of the heat treatment condition is heating to 850 ° C. or higher. This heat treatment may be performed also as a heat treatment of the heat-resistant base material 11, or may be performed by directly incorporating a turbine blade coated with a coating solution or slurry into a gas turbine and exposing it to combustion gas.

  Thus, the turbine blade in which the metal bonding layer 12 and the ceramic layer 13 are formed on the surface of the heat-resistant substrate 11 and the porous layer 14 and the dense layer 15 are formed on the ceramic layer 13 is completed.

  As described above, in some embodiments, a coating solution containing an alkoxide compound of zirconium and a zirconia stabilizing element is applied to the porous layer 14 formed on the heat resistant substrate 11, and the coating solution is applied. By heating the heat-resistant substrate 11, a dense layer 15 that is a zirconia film can be formed on the porous layer 14. In this method, since the film can be formed at a temperature of, for example, about 850 ° C., which is a sufficiently low process temperature condition as compared with the case where the zirconia film is formed by thermal spraying, cracking of the dense layer 15 can be suppressed. it can. This makes it difficult for the corrosive substance to penetrate into the dense layer 15, so that the penetration of the corrosive substance into the porous layer 14, the metal bonding layer 12, and the heat resistant substrate 11 can be effectively suppressed. The durability of the metal bonding layer 12 and the heat resistant substrate 11 can be further improved. That is, in some embodiments described above, since the durability of the TBC layer 10 can be further improved, the durability of the turbine blade can be further improved.

  Since the thermal barrier coating manufacturing method according to some embodiments includes a porous layer forming step, the porous layer 14 can be formed on the assumption that the dense layer 15 is generated on the porous layer 14. Thereby, for example, the porous layer 14 is formed to have a porosity and a thickness that can ensure the required thermal conductivity, assuming that the dense layer 15 has a role of suppressing the penetration of corrosive substances. it can. Therefore, the durability of the porous layer 14 and the heat resistant substrate 11 can be improved.

  In some embodiments, the zirconium alkoxide compound comprises at least one of zirconium ethoxide, zirconium propoxide, or zirconium butoxide, so that the coating is a zirconia coating from a coating solution at a temperature well below the melting point of zirconia. The dense layer 15 can be generated, and the manufacturing cost of the TBC layer 10 can be suppressed. That is, since the heating temperature when heating the heat-resistant substrate 11 coated with the coating liquid can be kept low, the energy cost required for heating and the cost of the apparatus for heating can be suppressed, and the production of the thermal barrier coating Cost can be reduced. Moreover, when the heat processing with respect to the heat-resistant base material 11 or the porous layer 14 is required, since this heat processing and the heat processing for producing | generating the dense layer 15 can be combined, the manufacturing cost of the TBC layer 10 is further increased. Can be suppressed.

  In some embodiments, since the coating liquid contains a dispersion stabilizer, the liquid quality of the coating liquid is stabilized, and the alkoxide compound is less likely to undergo changes such as decomposition and aggregation over time. Thereby, handling of a coating liquid becomes easy and manufacture of the TBC layer 10 becomes easy. Further, since the quality of the coating solution is stabilized, the quality of the dense layer 15 to be produced is also stabilized, and the performance of the TBC layer 10 is stabilized.

  In some embodiments, the dispersion stabilizer comprises an alcohol that is at least one of methanol or ethanol. By using a lower alcohol such as methanol or ethanol as a dispersion stabilizer, the liquid containing the alkoxide compound can be appropriately stabilized.

  In some embodiments, the dispersion stabilizer comprises an acid such as formic acid or acetic acid. By adjusting the hydrogen ion concentration of the coating solution with this acid, the quality of the coating solution is stabilized, so that the handling of the coating solution is facilitated and the production of the TBC layer 10 is facilitated. Further, since the quality of the coating solution is stabilized, the quality of the dense layer 15 to be produced is also stabilized, and the performance of the TBC layer 10 is stabilized.

  In some embodiments described above, the YSZ particles 17 are included in the slurry as shown in FIG. 8, so that cracking of the dense layer 15 can be suppressed as described below. FIG. 8 is a schematic cross-sectional view enlarging the vicinity of the porous layer 14 to which the slurry is applied.

When the slurry is heat-treated, the volume of the coating liquid 18a in the slurry decreases due to volatilization of the volatile components of the coating liquid 18a in the slurry. Therefore, the thickness of the coating film 18 of the slurry is gradually reduced, and the interval between the YSZ particles 17a dispersed in the coating film 18 is reduced. At this time, since the YSZ particles 17a contained in the coating film 18 try to prevent the shrinkage of the coating film 18 (the dense layer 15) (that is, the shrinkage of the dense layer 15 is suppressed by the drag by the YSZ particles 17a). , Cracking of the dense layer 15 can be suppressed.
In addition, since the YSZ particles 17a are included in the coating film 18, the ratio of the coating solution 18a that is a component other than the YSZ particles 17a that shrinks during the heat treatment can be reduced, and the shrinkage force is reduced to form a dense layer. 15 cracks can be suppressed.
This makes it difficult for the corrosive substance to penetrate into the dense layer 15, so that the penetration of the corrosive substance into the porous layer 14, the metal bonding layer 12, and the heat resistant substrate 11 can be effectively suppressed. The durability of the metal bonding layer 12 and the heat resistant substrate 11 can be further improved. That is, in some embodiments described above, since the durability of the TBC layer 10 can be further improved, the durability of the turbine blade can be further improved.

(Turbine blade and gas turbine)
The thermal barrier coating according to some embodiments described above is useful when applied to high temperature parts such as a moving blade and a stationary blade of an industrial gas turbine, or an inner cylinder and a tail cylinder of a combustor. Further, the present invention can be applied not only to industrial gas turbines but also to thermal barrier coating films for high-temperature parts of engines such as automobiles and jet aircraft. By providing the thermal barrier coating according to some embodiments described above on these members, it is possible to configure gas turbine blades and high-temperature components that are excellent in thermal cycle durability.

  FIG. 9 and FIG. 10 are perspective views showing a configuration example of a turbine blade to which the thermal barrier coating according to some embodiments described above can be applied. The gas turbine rotor blade 4 shown in FIG. 9 includes a tab tail 41, a platform 42, a blade portion 43, and the like that are fixed to the disk side. Further, the gas turbine stationary blade 5 shown in FIG. 10 includes an inner shroud 51, an outer shroud 52, a blade portion 53, and the like. The blade portion 53 is formed with a seal fin cooling hole 54, a slit 55, and the like. ing.

  Next, a gas turbine to which the turbine blades 4 and 5 shown in FIGS. 9 and 10 can be applied will be described below with reference to FIG. FIG. 11 is a diagram schematically illustrating a partial cross-sectional structure of a gas turbine according to an embodiment. The gas turbine 6 includes a compressor 61 and a turbine 62 that are directly connected to each other. The compressor 61 is configured as an axial flow compressor, for example, and sucks air or a predetermined gas as a working fluid from the suction port to increase the pressure. A combustor 63 is connected to the discharge port of the compressor 61, and the working fluid discharged from the compressor 61 is heated by the combustor 63 to a predetermined turbine inlet temperature. The working fluid heated to a predetermined temperature is supplied to the turbine 62. As shown in FIG. 11, the gas turbine stationary blades 5 described above are provided in a plurality of stages inside the casing of the turbine 62. Further, the above-described gas turbine rotor blade 4 is attached to the main shaft 64 so as to form a pair of stages with each stationary blade 5. One end of the main shaft 64 is connected to a rotating shaft 65 of the compressor 61, and the other end is connected to a rotating shaft of a generator (not shown).

  With such a configuration, when a high-temperature and high-pressure working fluid is supplied from the combustor 63 into the casing of the turbine 62, the working fluid expands in the casing, so that the main shaft 64 rotates and is connected to the gas turbine 6. A generator (not shown) is driven. That is, the pressure is dropped by each stationary blade 5 fixed to the casing, and the kinetic energy generated thereby is converted into rotational torque via each blade 4 attached to the main shaft 64. The generated rotational torque is transmitted to the main shaft 64, and the generator is driven.

  In general, the material used for the gas turbine blade is a heat-resistant alloy (for example, CM247L = commercially available alloy material of Canon Maskegon), and the material used for the gas turbine stationary blade is similarly a heat-resistant alloy (for example, IN938 = Inco) Commercially available alloy materials). That is, as a material constituting the turbine blade, a heat-resistant alloy that can be used as the heat-resistant base material 11 in the thermal barrier coating according to some embodiments described above is used. Therefore, if the thermal barrier coating according to some embodiments described above is applied to these turbine blades, a turbine blade excellent in thermal barrier effect and durability can be obtained, so that it is used in a higher temperature environment. And a long-life turbine blade can be realized. In addition, being applicable in a higher temperature environment means that the temperature of the working fluid can be increased, thereby improving the efficiency of the gas turbine.

The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.
For example, in some embodiments described above, the particles dispersed in the dense layer 15 are YSZ particles 17. However, for example, even a particle made of a substance other than YSZ is a substance having a linear expansion coefficient close to the linear expansion coefficient of the portion other than the particles of the dense layer 15, and has corrosion resistance and strength against corrosive substances. Any particles made of a substance equivalent to YSZ may be used. Examples of such substances include, for example, stabilized zirconia containing a stabilizing element other than yttrium.

  For example, in some embodiments described above, the stabilizing element of zirconia in the porous layer 14, the dense layer 15, and the YSZ particles 17 is yttrium, but is not limited to yttrium, and is an alkaline earth metal such as magnesium or calcium. It may be either an element or a rare earth element, and may be two or more of these elements.

  For example, in some embodiments described above, the YSZ particles 17 dispersed in the dense layer 15 are one type or two types of YSZ particles 17 having different particle sizes. However, the YSZ particles 17 dispersed in the dense layer 15 may be three or more types of YSZ particles 17 having different particle diameters.

For example, the thermal barrier coating manufacturing method according to some embodiments described above includes a metal bonding layer forming step, a porous layer forming step, and a dense layer forming step. However, the dense layer 15 may be formed on the surface side of the porous layer 14 by the above-described dense layer forming step with respect to the heat-resistant substrate 11 on which the metal bonding layer 12 and the porous layer 14 have already been formed. .
Thereby, for example, the dense layer 15 can be formed on a conventional turbine blade having a porous layer similar to the porous layer 14. Further, in the maintenance of the turbine blades 4 and 5 having the TBC layer 10 according to some embodiments described above, the new dense layer 15 can be formed after the old dense layer 15 is removed.

  For example, the TBC layer 10 according to some embodiments described above may be provided on the entire surface of the heat-resistant base material 11 or may be provided only on a part of the surface of the heat-resistant base material 11.

4 Gas turbine blades (turbine blades, blades)
5 Gas turbine stationary blade (turbine blade, stationary blade)
6 Gas Turbine 10 Thermal Barrier Coating (TBC) Layer 11 Heat-resistant Substrate 12 Metal Bonding Layer 13 Ceramic Layer 14 Porous Layer 15 Dense Layer 16 Pore 17, 17a, 17b, 17c YSZ Particle 18 Coating 18a Coating Solution

Claims (17)

A porous layer formed on a substrate, comprising cubic or tetragonal zirconia and a first zirconia stabilizing element that stabilizes cubic or tetragonal zirconia;
A cubic layer or tetragonal zirconia and a second zirconia stabilizing element that stabilizes cubic or tetragonal zirconia, formed on the porous layer, and a dense layer denser than the porous layer; ,
Particles dispersed in the dense layer;
A thermal barrier coating.   The thermal barrier coating according to claim 1, wherein the particles are formed of stabilized zirconia including a third zirconia stabilizing element that stabilizes cubic or tetragonal zirconia.   The heat shield according to claim 2, wherein the first zirconia stabilizing element, the second zirconia stabilizing element, and the third zirconia stabilizing element include any of magnesium, an alkaline earth metal element, and a rare earth element. coating.   The thermal barrier coating according to any one of claims 1 to 3, wherein the particles include at least two types of particles having different particle sizes. A turbine blade body,
The thermal barrier coating according to any one of claims 1 to 4, which is provided so as to cover a surface of the turbine blade body.
Turbine blades equipped with. The base material in which a porous layer containing cubic or tetragonal zirconia and a first zirconia stabilizing element for stabilizing cubic or tetragonal zirconia is formed on at least a part of the surface of the base material. For the porous layer,
Applying a liquid comprising a zirconium alkoxide compound and a second zirconia stabilizing element that stabilizes cubic or tetragonal zirconia;
Heating the base material coated with the liquid to form a film on the porous layer. Forming a porous layer on at least a part of the surface of the substrate, comprising cubic or tetragonal zirconia and a first zirconia stabilizing element that stabilizes the cubic or tetragonal zirconia;
The method for producing a thermal barrier coating according to claim 6, further comprising:   The method for producing a thermal barrier coating according to claim 6 or 7, wherein the alkoxide compound contains at least one of ethoxide, propoxide, or butoxide.   The method for producing a thermal barrier coating according to any one of claims 6 to 8, wherein the liquid further contains a dispersion stabilizer for the alkoxide compound.   The method for producing a thermal barrier coating according to claim 9, wherein the dispersion stabilizer contains an alcohol that is at least one of methanol and ethanol.   The method for producing a thermal barrier coating according to claim 10, wherein the total molar ratio of the alcohol in the liquid is 5% or more.   The method for producing a thermal barrier coating according to any one of claims 9 to 11, wherein the dispersion stabilizer contains an acid.   The method for producing a thermal barrier coating according to claim 12, wherein a molar ratio of the acid in the liquid is 1% or more.   The thermal barrier coating according to any one of claims 6 to 13, wherein the first zirconia stabilizing element and the second zirconia stabilizing element include any of magnesium, an alkaline earth metal element, and a rare earth element. Manufacturing method.   The total of the molar ratio of the said 2nd zirconia stabilization element in the said liquid is 5% or more with respect to the zirconium contained in the said liquid, The manufacture of the thermal barrier coating as described in any one of Claims 6 thru | or 14 Method. The liquid includes particles,
The method for producing a thermal barrier coating according to any one of claims 6 to 15, wherein the base material coated with the liquid is heated to produce the coating film containing the particles on the porous layer.   The method for producing a thermal barrier coating according to claim 16, wherein the particles are formed of stabilized zirconia containing a third zirconia stabilizing element that stabilizes cubic or tetragonal zirconia.

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