阅读说明：本技术 隔热涂层形成方法、隔热涂层以及高温构件 (method for forming thermal barrier coating, and high-temperature member ) 是由 冈岛芳史 鸟越泰治 于 2018-04-26 设计创作，主要内容包括：隔热涂层具备形成在耐热合金基材上且包含陶瓷的陶瓷层(120)。陶瓷层(120)具有：第一致密层(121)；中间气孔层(122),其层叠在第一致密层(121)上,密度比第一致密层(121)大,且形成有多个气孔；以及第二致密层(123),其层叠在中间气孔层(122)上,密度比中间气孔层(122)小。(The thermal barrier coating layer is provided with a ceramic layer (120) which is formed on the heat-resistant alloy base material and contains ceramic. The ceramic layer (120) has: a first dense layer (121); an intermediate pore layer (122) which is laminated on the first dense layer (121), has a density higher than that of the first dense layer (121), and has a plurality of pores formed therein; and a second dense layer (123) laminated on the intermediate gas pore layer (122) and having a density smaller than that of the intermediate gas pore layer (122).)

1. A thermal barrier coating, wherein,

the thermal barrier coating is provided with a ceramic layer formed on a heat-resistant alloy substrate and containing a ceramic,

the ceramic layer has:

A first dense layer;

An intermediate pore layer laminated on the first dense layer, having a density higher than that of the first dense layer, and having a plurality of pores formed therein; and

A second dense layer laminated on the intermediate gas orifice layer, the second dense layer having a density less than that of the intermediate gas orifice layer.

2. the thermal barrier coating of claim 1,

The porosity continuously changes at a first boundary portion that is a boundary portion between the intermediate pore layer and the first dense layer and at a second boundary portion that is a boundary portion between the intermediate pore layer and the second dense layer.

3. The thermal barrier coating of claim 1 or 2,

The porosity of the intermediate pore layer is 10% or more and 20% or less.

4. The thermal barrier coating of any one of claims 1 to 3,

The first dense layer and the second dense layer have a porosity of 10% or less and 5% or more.

5. the thermal barrier coating of any one of claims 1 to 4,

In the first dense layer, first longitudinal cracks extending in the thickness direction are dispersed in the planar direction,

In the second dense layer, second longitudinal cracks extending in the thickness direction are dispersed in the planar direction.

6. The thermal barrier coating of claim 5,

The first longitudinal crack and the second longitudinal crack extend obliquely with respect to the surface of the ceramic layer.

7. The thermal barrier coating of claim 5 or 6,

An angle of inclination of the first longitudinal crack relative to the surface of the ceramic layer is different from an angle of inclination of the second longitudinal crack relative to the surface of the ceramic layer.

8. A method for forming a thermal barrier coating, wherein,

the thermal barrier coating forming method comprises a ceramic layer forming step of forming a ceramic layer containing ceramic on the surface of a heat-resistant alloy substrate,

The ceramic layer forming step includes:

A first dense layer forming step of forming a first dense layer;

A pore layer forming step of forming an intermediate pore layer having a density higher than that of the first dense layer and having a plurality of pores formed therein on the first dense layer, the pore layer forming step being performed after the first dense layer forming step; and

And a second dense layer forming step of forming a second dense layer having a density lower than that of the intermediate pore layer on the intermediate pore layer, the second dense layer forming step being performed after the pore layer forming step.

9. The thermal barrier coating forming method according to claim 8,

In the ceramic layer forming step, a thermal spraying method is used,

In the first dense layer forming step and the second dense layer forming step, a distance between the spray hole of the spray gun and the surface of the spray target is shorter than in the pore layer forming step.

10. The thermal barrier coating forming method according to claim 8 or 9,

In the first dense layer forming step, the first dense layer is formed so that first longitudinal cracks extending in the thickness direction are dispersed in the surface direction,

In the second dense layer forming step, the second dense layer is formed so that second longitudinal cracks extending in the thickness direction are dispersed in the surface direction.

11. the thermal barrier coating forming method according to any one of claims 8 to 10,

The particle diameter of the sprayed particles is 0.1 μm or more and 1.0 μm or less.

12. The thermal barrier coating forming method according to any one of claims 8 to 11,

in at least a part of the ceramic layer forming step, suspension plasma sputtering is used.

13. a high-temperature structural member, wherein,

The high-temperature member is provided with:

A heat resistant alloy substrate; and

A ceramic layer formed on the heat-resistant alloy substrate and including a ceramic,

The ceramic layer has:

A first dense layer;

An intermediate pore layer laminated on the first dense layer, having a density higher than that of the first dense layer, and having a plurality of pores formed therein; and

a second dense layer laminated on the intermediate gas orifice layer, the second dense layer having a density less than that of the intermediate gas orifice layer.

14. the thermal barrier coating of claim 1,

In the ceramic layer, longitudinal cracks extending in a thickness direction are dispersed in a plane direction,

the longitudinal crack extends obliquely with respect to the surface of the ceramic layer.

15. The thermal barrier coating of claim 14,

The inclination angle of the longitudinal crack is different between the surface side of the ceramic layer and the heat-resistant alloy substrate side of the ceramic layer.

16. The thermal barrier coating of claim 14 or 15,

The distribution rate of the longitudinal cracks per 1mm is 6/mm or more and 12/mm or less.

17. The thermal barrier coating of any one of claims 14 to 16,

the longitudinal crack extends intermittently.

18. The thermal barrier coating of any one of claims 14 to 17,

all of the plurality of longitudinal cracks are inclined toward one side of the plane direction as facing the surface of the ceramic layer.

19. The thermal barrier coating of any one of claims 14 to 18,

The inclination angle of the longitudinal crack is 45 ° or more and 80 ° or less with respect to the surface of the ceramic layer.

20. the thermal barrier coating forming method according to claim 8,

A ceramic layer containing ceramic is formed on a heat-resistant alloy base material by inclining a spray gun at a predetermined inclination angle with respect to the surface of the heat-resistant alloy base material and spraying using a suspension in which spray particles are dispersed, the ceramic layer containing ceramic in which longitudinal cracks extending in the thickness direction and extending at an inclination angle are dispersed in the planar direction.

21. The thermal barrier coating forming method according to claim 20,

The sputtering is suspension plasma sputtering.

22. the thermal barrier coating forming method according to claim 20 or 21,

The particle diameter of the thermal spraying particles is more than 0.1 μm and less than 1.0 μm.

23. The high temperature component of claim 13,

The high-temperature member is provided with:

a heat resistant alloy substrate; and

A ceramic layer formed on the heat-resistant alloy base material and containing a ceramic in which longitudinal cracks extending in a thickness direction are dispersed in a plane direction,

the longitudinal crack extends obliquely with respect to the surface of the ceramic layer.

Technical Field

the invention relates to a method for forming a thermal barrier coating, and a high-temperature member.

the present application claims priority based on japanese patent application No. 2017-087472 and japanese patent application No. 2017-087471, which are filed on 26.4.2017, and the contents of which are incorporated herein by reference.

Background

In a gas turbine, the temperature of the gas used is set high in order to improve the efficiency thereof. Turbine components such as blades and vanes exposed to such high-temperature gas are coated with a Thermal Barrier Coating (TBC) on the surface thereof. The thermal barrier coating is formed by thermally spraying a thermal spray material (for example, a ceramic material having a low thermal conductivity) having a low thermal conductivity on the surface of the turbine member as the object to be thermally sprayed. By forming the thermal barrier coating on the surface, the temperature of the high-temperature member exposed to high-temperature and high-pressure environments is reduced and the durability is improved.

Patent document 1 describes a method using a Suspension Plasma Spray (sustension Plasma Spray) as a method for forming a thermal barrier coating on a metal component of a gas turbine engine. Suspension plasma spraying is performed using a suspension in which fine particles are dispersed in a water or alcohol-based carrier. Suspension plasma spraying deposits fine particles, which are evaporated or burned by a plasma jet and melted, on a contact surface. As a result, a uniform ceramic layer is formed on the surface of the substrate from the molten fine particles.

Disclosure of Invention

Problems to be solved by the invention

However, as a dense ceramic layer in the thermal barrier coating, a dvc (dense vertical crack) coating having a longitudinal crack is sometimes formed. DVC coatings improve erosion resistance by becoming a dense structure with a longitudinal crack structure. However, it is known that the DVC coating layer has a dense structure, and thus has a small porosity, and may have a low heat insulating property. That is, in the thermal barrier coating, when the porosity is decreased in order to improve erosion resistance, the thermal conductivity is increased and the thermal insulation performance is decreased.

The purpose of the present invention is to provide a method for forming a thermal barrier coating, and a high-temperature member, which are capable of improving the thermal barrier effect while suppressing a decrease in erosion resistance.

Means for solving the problems

A thermal barrier coating according to a first aspect of the present invention includes a ceramic layer formed on a heat-resistant alloy substrate and including a ceramic, the ceramic layer including: a first dense layer; an intermediate pore layer laminated on the first dense layer, having a density higher than that of the first dense layer, and having a plurality of pores formed therein; and a second dense layer laminated on the intermediate gas pore layer and having a density lower than that of the intermediate gas pore layer.

according to such a structure, an intermediate pore layer is formed between the first dense layer and the second dense layer, so that heat input to the ceramic layer in the thickness direction is blocked by the intermediate pore layer. As a result, the thermal conductivity of the ceramic layer can be reduced. In addition, in the ceramic layer, the first dense layer is formed on the side of the heat-resistant alloy base material, so that the adhesion to the heat-resistant alloy base material can be secured. In addition, the second dense layer is formed on the front surface side of the ceramic layer, so that erosion resistance can be ensured.

in the thermal barrier coating according to the second aspect of the present invention, in addition to the first aspect, the porosity may continuously change at a first boundary portion between the intermediate pore layer and the first dense layer and at a second boundary portion between the intermediate pore layer and the second dense layer.

In the thermal barrier coating according to a third aspect of the present invention, in addition to the first or second aspect, the intermediate pore layer may have a porosity of 10% or more and 20% or less.

With such a configuration, the effect of inhibiting heat input to the ceramic layer in the thickness direction is increased in a wide region in the surface direction. As a result, the thermal conductivity in the overcoat layer can be greatly reduced without greatly reducing the erosion resistance in the intermediate gas orifice layer.

In the thermal barrier coating according to a fourth aspect of the present invention, in addition to any one of the first to third aspects, the first dense layer and the second dense layer may have a porosity of 10% or less and 5% or more.

In the thermal barrier coating according to a fifth aspect of the present invention, in addition to any one of the first to fourth aspects, the first dense layer may have first longitudinal cracks extending in the thickness direction dispersed therein in the planar direction, and the second dense layer may have second longitudinal cracks extending in the thickness direction dispersed therein in the planar direction.

In the thermal barrier coating according to a sixth aspect of the present invention, in the fifth aspect, the first longitudinal cracks and the second longitudinal cracks may extend obliquely with respect to the surface of the ceramic layer.

By adopting such a structure, the heat input in the ceramic layer in the thickness direction is hindered by the first longitudinal cracks and the second longitudinal cracks that extend obliquely. Therefore, the thermal conductivity in the ceramic layer can be reduced by the first longitudinal cracks and the second longitudinal cracks. On the other hand, the more densely the ceramic layer is formed, the more the first longitudinal cracks and the second longitudinal cracks are formed, and the decrease in erosion resistance can be suppressed.

In the thermal barrier coating according to a seventh aspect of the present invention, in addition to the fifth or sixth aspect, an inclination angle of the first longitudinal crack with respect to the surface of the ceramic layer may be different from an inclination angle of the second longitudinal crack with respect to the surface of the ceramic layer.

in addition, a thermal barrier coating forming method according to an eighth aspect of the present invention includes a ceramic layer forming step of forming a ceramic layer including a ceramic on a surface of a heat-resistant alloy base material, the ceramic layer forming step including: a first dense layer forming step of forming a first dense layer; a pore layer forming step of forming an intermediate pore layer having a density higher than that of the first dense layer and having a plurality of pores formed therein on the first dense layer, the pore layer forming step being performed after the first dense layer forming step; and a second dense layer forming step of forming a second dense layer having a density lower than that of the intermediate pore layer on the intermediate pore layer, the second dense layer forming step being performed after the pore layer forming step.

By adopting such a structure, an intermediate pore layer is formed between the first dense layer and the second dense layer, so that heat input to the ceramic layer in the thickness direction is hindered by the intermediate pore layer. As a result, the thermal conductivity of the ceramic layer can be reduced. In addition, in the ceramic layer, the first dense layer is formed on the side of the heat-resistant alloy base material, so that the adhesion to the heat-resistant alloy base material can be secured. In addition, the second dense layer is formed on the front surface side of the ceramic layer, so that erosion resistance can be ensured.

In the thermal barrier coating forming method according to a ninth aspect of the present invention, in addition to the eighth aspect, a thermal spraying method may be used in the ceramic layer forming step, and a distance between a spray hole of a thermal spraying gun and a surface of a thermal spraying target may be shorter in the first dense layer forming step and the second dense layer forming step than in the pore layer forming step.

in the thermal barrier coating forming method according to a tenth aspect of the present invention, in addition to the eighth or ninth aspect, the first dense layer may be formed so that first longitudinal cracks extending in the thickness direction are dispersed in the surface direction in the first dense layer forming step, and the second dense layer may be formed so that second longitudinal cracks extending in the thickness direction are dispersed in the surface direction in the second dense layer forming step.

in the thermal barrier coating forming method according to the eleventh aspect of the present invention, in addition to any one of the eighth to tenth aspects, the thermal spray particles may have a particle diameter of 0.1 μm or more and 1.0 μm or less.

In the thermal barrier coating forming method according to a twelfth aspect of the present invention, in addition to any one of the eighth to eleventh aspects, the ceramic layer forming step may be performed at least partially by using a suspension plasma spraying method.

in addition, a high-temperature member according to a thirteenth aspect of the present invention includes: a heat resistant alloy substrate; and a ceramic layer formed on the heat-resistant alloy base material and including a ceramic, the ceramic layer having: a first dense layer; an intermediate pore layer laminated on the first dense layer, having a density higher than that of the first dense layer, and having a plurality of pores formed therein; and a second dense layer laminated on the intermediate gas pore layer and having a density lower than that of the intermediate gas pore layer.

In the thermal barrier coating according to a fourteenth aspect of the present invention, in addition to the first aspect, the ceramic layer may have longitudinal cracks dispersed therein in a planar direction, the longitudinal cracks extending in a thickness direction, the longitudinal cracks extending obliquely to a surface of the ceramic layer.

According to such a structure, heat input in the ceramic layer in the thickness direction is hindered by the obliquely extending longitudinal cracks. Therefore, the thermal conductivity in the ceramic layer can be reduced by the longitudinal cracks. On the other hand, the more the longitudinal cracks are formed, the more densely the ceramic layer is formed, and the decrease in erosion resistance can be suppressed.

In the thermal barrier coating according to a fifteenth aspect of the present invention, in addition to the fourteenth aspect, the inclination angle of the longitudinal crack may be different between the surface side of the ceramic layer and the heat-resistant alloy base material side of the ceramic layer.

In the thermal barrier coating according to a sixteenth aspect of the present invention, in addition to the fourteenth or fifteenth aspect, the longitudinal cracks may have a distribution rate per 1mm of 6 or more and 12 or less per mm.

In the thermal barrier coating of the seventeenth aspect of the present invention, in addition to any one of the fourteenth to sixteenth aspects, the longitudinal crack may extend intermittently.

In the thermal barrier coating according to an eighteenth aspect of the present invention, in addition to any one of the fourteenth to seventeenth aspects, all of the plurality of longitudinal cracks may be inclined toward one side in the plane direction as going toward the surface of the ceramic layer.

With such a structure, heat input in the thickness direction is inhibited in a wide area in the surface direction of the ceramic layer. As a result, the thermal conductivity in the ceramic layer can be reduced in a wide range.

In the thermal barrier coating according to a nineteenth aspect of the present invention, in addition to any one of the fourteenth to eighteenth aspects, an inclination angle of the longitudinal crack may be 45 ° or more and 80 ° or less with respect to the surface of the ceramic layer.

With such a configuration, the inclination angle is reduced, and the effect of inhibiting heat input in the thickness direction by the longitudinal crack is increased. As a result, the thermal conductivity of the ceramic layer can be greatly reduced. In addition, by setting the inclination angle of the longitudinal crack to 45 degrees or more, it is possible to suppress the adhesion of the sprayed particles to the surface when the ceramic layer is formed. Therefore, a decrease in the manufacturing efficiency of the ceramic layer can be suppressed.

A thermal barrier coating forming method according to a twentieth aspect of the present invention is the eighth aspect, wherein the thermal spray gun is inclined at a predetermined inclination angle with respect to the surface of the heat-resistant alloy base material, and the thermal spray is performed using a suspension in which thermal spray particles are dispersed, thereby forming the ceramic layer including the ceramic on the heat-resistant alloy base material, in which the longitudinal cracks extending in the thickness direction and extending at the inclination angle are dispersed in the planar direction.

By adopting such a structure, the heat input in the ceramic layer in the thickness direction is hindered by the obliquely extending longitudinal cracks. Therefore, the thermal conductivity in the ceramic layer can be reduced by the longitudinal cracks. On the other hand, the more the longitudinal cracks are formed, the more densely the ceramic layer is formed, and the decrease in erosion resistance can be suppressed. Further, since the ceramic layer is formed by the suspension plasma spraying, the particle diameter of the spraying particle forming the ceramic layer is reduced. As a result, the ceramic layer can be formed into a very fine structure. This also improves the adhesion of the ceramic layer after formation.

In the thermal barrier coating forming method according to a twenty-first aspect of the present invention, in addition to the twentieth aspect, the spraying may be suspension plasma spraying.

In the method of forming a thermal barrier coating according to a twenty-second aspect of the present invention, in addition to the twentieth or twenty-first aspect, the thermal spray particles may have a particle diameter of 0.1 μm or more and 1.0 μm or less.

in a thirteenth aspect of the high-temperature member according to the twenty-third aspect of the present invention, the high-temperature member may include: a heat resistant alloy substrate; and a ceramic layer formed on the heat-resistant alloy base material, the ceramic layer including a ceramic in which longitudinal cracks extending in a thickness direction are dispersed in a plane direction, the longitudinal cracks extending obliquely with respect to a surface of the ceramic layer.

effects of the invention

according to the above-described method for forming a thermal barrier coating, and high-temperature member, it is possible to improve the thermal barrier effect while suppressing a decrease in erosion resistance.

Drawings

fig. 1 is a schematic configuration diagram of a gas turbine according to an embodiment of the present invention.

Fig. 2 is a schematic structural perspective view of a bucket according to an embodiment of the present invention.

Fig. 3 is an enlarged sectional view of a main part of a rotor blade illustrating a thermal barrier coating according to an embodiment of the present invention.

Fig. 4 is a process diagram illustrating steps of a thermal barrier coating layer forming method according to a first embodiment of the present invention.

Fig. 5 is a graph of the relationship between the thermal conductivity and the porosity of the overcoat layer in the embodiment of the present invention, which is obtained by simulation.

Fig. 6 is a graph of the relationship between the thermal conductivity of the overcoat layer having a longitudinal crack formed thereon and the inclination angle of the longitudinal crack in the embodiment of the present invention obtained by simulation.

Fig. 7 is an enlarged cross-sectional view of a main portion of a rotor blade illustrating a thermal barrier coating according to a modification of the present invention.

Fig. 8 is an enlarged sectional view of a main part of a rotor blade illustrating a thermal barrier coating according to a modification of the present invention.

Detailed Description

hereinafter, embodiments of the present invention will be described with reference to fig. 1 to 7.

As shown in fig. 1, a gas turbine 1 of the present embodiment includes a compressor 2, a combustor 3, a turbine main body 4, and a rotor 5. The compressor 2 takes in a large amount of air to the inside and compresses it. The combustor 3 mixes fuel with the compressed air a compressed by the compressor 2 and burns them.

The turbine body 4 converts thermal energy of the combustion gas G introduced from the combustor 3 into rotational energy. The turbine main body 4 generates power by blowing the combustion gas G to the rotor blades 7 provided on the rotor 5 to convert thermal energy of the combustion gas G into mechanical rotational energy. In the turbine main body 4, a plurality of vanes 8 are provided in a casing 6 of the turbine main body 4 in addition to a plurality of blades 7 on the rotor 5 side. In the turbine main body 4, the blades 7 and the vanes 8 are alternately arranged in the axial direction of the rotor 5. The rotor 5 transmits a part of the power of the rotation of the turbine body 4 to the compressor 2 to rotate the compressor 2.

In the following, in this embodiment, the rotor blade 7 of the turbine main body 4 is described as an example of the high-temperature member of the present invention.

As shown in FIG. 2, the bucket 7 has a bucket body 70 and a thermal barrier coating 100. The blade body 70 is a heat-resistant alloy base material made of a known heat-resistant alloy material such as a Ni-based alloy. The rotor blade body 70 of the present embodiment includes a blade body 71, a platform 72, a blade root 73, and a shroud 74.

the blade body 71 has an airfoil shape in cross section. The vane body portion 71 is disposed in the flow path of the combustion gas G in the casing 6 of the turbine body 4. The platform portion 72 is provided at the base end of the blade main body portion 71. The terrace portion 72 defines a flow path of the combustion gas G on the base end side of the vane body portion 71. The root portion 73 is formed to protrude from the platform portion 72 toward the side opposite to the blade main body portion 71. The shroud portion 74 is provided at the tip of the blade body portion 71. The shroud portion 74 defines a flow path of the combustion gas G on the tip end side of the blade body portion 71.

as shown in fig. 3, the thermal barrier coating 100 is formed on the surface of the bucket body 70 as a heat-resistant alloy base material. The thermal barrier coating 100 is formed to cover the surface of the blade body 71, the surface of the platform 72 on the side connected to the blade body 71, and the surface of the shroud portion 74 on the side connected to the blade body 71, out of the surfaces of the blade body 70. The thermal barrier coating 100 of the present embodiment is formed by suspension plasma spraying, which will be described later. The thermal barrier coating 100 of the present embodiment includes a bond coat layer 110 and a top coat layer (ceramic layer) 120.

The bond coat 110 is formed directly on the surface of the bucket body 70. The bond coat 110 inhibits delamination of the outer coating 120 from the blade body 70. The bond coat 110 is a metallic bond layer that is excellent in corrosion resistance and oxidation resistance. The bond coat 110 is formed by, for example, spraying a metal spray powder of MCrAlY alloy as a spray material onto the surface of the blade body 70. Here, "M" of the MCrAlY alloy constituting the bond coat 110 denotes a metal element. The metal element "M" is composed of, for example, a single metal element such as Ni or Co, or a combination of two or more of these.

the outer coating 120 is formed on the bucket body 70 via the bond coat 110. The overcoat layer 120 has a ceramic-containing layer in which longitudinal cracks C extending in the thickness direction are dispersed in the in-plane direction. Here, the plane direction refers to a direction along the surface of the overcoat layer 120. The overcoat layer 120 of the present embodiment is formed to have a thickness of 0.3mm to 1.5 mm. Overcoat 120 has a first dense layer 121, an intermediate gas pore layer 122, and a second dense layer 123.

The first dense layer 121 is directly laminated on the bond coat layer 110. In the first dense layer 121, first longitudinal cracks C1 are dispersed as longitudinal cracks C in the surface direction of the surface extension. Therefore, the first dense layer 121 has a plurality of first longitudinal cracks C1 formed therein so as to be separated in the plane direction. The first dense layer 121 of the present embodiment is, for example, a dense dvc (dense Vertical crack) coating in which the first longitudinal cracks C1 are dispersed in the plane direction. The first dense layer 121 is formed in the overcoat layer 120 at a position closest to the heat-resistant alloy substrate side. Examples of the thermal spray material used for forming the first dense layer 12 include yttria-stabilized zirconia (YSZ) and ytterbium-stabilized zirconia (YbSZ) which is zirconia (ZrO2) locally stabilized by ytterbium oxide (Yb2O 3).

The first longitudinal crack C1 extends at an inclination angle α with respect to the surface of the overcoat layer 120. Specifically, the first longitudinal crack C1 extends in a direction along a virtual straight line connecting the proximal end, which is the surface side of the heat resistant alloy base material, and the distal end, which is the surface side of the top coat layer 120, in the thickness direction. The extending direction of the first longitudinal crack C1 is inclined with respect to the plane direction in which the surface of the overcoat layer 120 extends. Therefore, the first longitudinal crack C1 extends from the base end toward one side of the surface direction of the outer coating 120 with respect to the base end. The inclination angle α in the present embodiment is an angle of the extending direction with respect to the plane direction. In the present embodiment, all of the plurality of first longitudinal cracks C1 are inclined in the same direction. That is, all of the plurality of first longitudinal cracks C1 are inclined toward one side of the plane direction as they go toward the surface of the outer coating layer 120. The first longitudinal crack C1 is not inclined only at a part of the base end side and the tip end side thereof, but is inclined over the entire region in the thickness direction.

The inclination angle α in the present embodiment is preferably 45 ° or more and 80 ° or less with respect to the surface of the overcoat layer 120. More preferably, the inclination angle α is an angle of 50 ° or more and 70 ° or less with respect to the surface of overcoat 120. The inclination angle α is particularly preferably an angle of 55 ° or more and 65 ° or less with respect to the surface of overcoat layer 120.

The first dense layer 121 preferably has a distribution ratio of the first longitudinal cracks C1 of 6/mm or more and 12/mm or less per 1 mm. More preferably, the first dense layer 121 has a distribution ratio of the first longitudinal cracks C1 of 8 or more and 10 or less per 1 mm.

The porosity of the first dense layer 121 is preferably in the range of 10% or less and 5% or more. The porosity in the present embodiment does not mean only the occupancy of the pores P per unit volume, but means the occupancy of the longitudinal cracks C and the pores P in total.

An intermediate gas orifice layer 122 is laminated on the first dense layer 121. The intermediate pore layer 122 has a density greater than that of the first dense layer 121, and is formed with a plurality of pores P. Therefore, the intermediate pore layer 122 is a porous film formed with a porosity larger than that of the first dense layer 121, and has almost no longitudinal crack C inside. The intermediate pore layer 122 of this embodiment is formed with the same thickness as the first dense layer 121. The intermediate gas hole layer 122 of this embodiment is formed of the same sputtered material as the first dense layer 121.

the intermediate pore layer 122 of the present embodiment preferably has a porosity of 10% or more and 20% or less. More preferably, the porosity of the intermediate pore layer 122 is 12% or more and 18% or less. The porosity of the intermediate pore layer 122 is particularly preferably 14% or more and 16% or less.

At the boundary portion between the intermediate pore layer 122 and the first dense layer 121, i.e., the first boundary portion, the porosity continuously changes. Therefore, the porosity is formed so as to gradually increase from the vicinity of the center in the thickness direction of the first dense layer 121 toward the vicinity of the center in the thickness direction of the intermediate pore layer 122.

The second dense layer 123 is laminated directly to the intermediate gas bore layer 122. In the second dense layer 123, second longitudinal cracks C2 are dispersed in the plane direction as longitudinal cracks C. Therefore, in the second dense layer 123, a plurality of second longitudinal cracks C2 are separately formed in the plane direction. The second dense layer 123 has a density greater than the intermediate gas bore layer 122. The second dense layer 123 is formed in the overcoat layer 120 at a position on the most surface side. Thus, the surface of second dense layer 123 is the surface of overcoat 120. The second dense layer 123 of the present embodiment is, for example, a dense DVC coating in which the second longitudinal cracks C2 are dispersed in the plane direction. The second dense layer 123 of the present embodiment is a film having the same structure as the first dense layer 121. Therefore, the sputtering material used for forming the second dense layer 123 is the same sputtering material as that of the first dense layer 121.

The second longitudinal crack C2 extends at an oblique angle α relative to the surface of the overcoat 120, as does the first longitudinal crack C1. Specifically, the second longitudinal crack C2 extends in a direction along a virtual straight line connecting the proximal end, which is the surface side of the heat resistant alloy base material, and the distal end, which is the surface side of the top coat layer 120, in the thickness direction. The extending direction of the second longitudinal crack C2 is inclined with respect to the plane direction in which the surface of the overcoat layer 120 extends. Therefore, the second longitudinal crack C2 extends toward one side of the surface direction from the base end toward the outer coating 120 with respect to the base end, similarly to the first longitudinal crack C1. The second longitudinal crack C2 of the present embodiment is inclined in the same direction and at the same angle as the first longitudinal crack C1 as the first longitudinal crack C1. All of the plurality of second longitudinal cracks C2 are inclined toward the same direction. That is, all of the plurality of second longitudinal cracks C2 are inclined toward one side of the face direction as being directed toward the surface of the outer coating layer 120. The second longitudinal crack C2 is not inclined only at a part of the base end side and the tip end side thereof, but is inclined over the entire region in the thickness direction.

In the second dense layer 123, the distribution ratio of the second longitudinal cracks C2 is preferably 6 or more and 12 or less per 1 mm. More preferably, the second dense layer 123 has a distribution ratio of the second longitudinal cracks C2 of 8 or more and 10 or less per 1 mm. The porosity of the second dense layer 123 is preferably in the range of 10% or less and 5% or more. It is preferable that the distribution rate of the second longitudinal cracks C2 per 1mm in the second dense layer 123 is the same as the distribution rate of the first longitudinal cracks C1 of the first dense layer 121. The porosity of the second dense layer 123 is preferably the same as the porosity of the first dense layer 121.

the porosity continuously changes at a second boundary portion which is a boundary portion between the intermediate pore layer 122 and the second dense layer 123. Therefore, the porosity is formed so as to gradually decrease from the vicinity of the center in the thickness direction of the intermediate pore layer 122 toward the vicinity of the center in the thickness direction of the second dense layer 123.

Next, a method S1 for manufacturing the high-temperature member will be explained. The method S1 for manufacturing a high-temperature member according to the present embodiment is a method for manufacturing the rotor blade 7 by using the rotor blade 7 as a high-temperature member. As shown in fig. 4, the method S1 for manufacturing a high-temperature member according to the present embodiment includes a bucket body preparation step S10 and a thermal barrier coating formation step S20.

In the rotor blade body preparation step S10, a heat-resistant alloy base material is prepared as the rotor blade body 70. In the rotor blade body preparation step S10 of the present embodiment, a material is prepared so as to be in the shape of a target high-temperature member (for example, the rotor blade body 70 in the present embodiment).

In the thermal barrier coating forming step S20, the thermal barrier coating 100 is formed on the surface of the rotor blade body 70 prepared in the rotor blade body preparing step S10 by the thermal barrier coating forming method S100. In the thermal barrier coating forming step S20 of the present embodiment, the bond coat layer 110 and the outer coat layer 120 are formed on the surface of the rotor blade body 70. The thermal barrier coating forming step S20 of the present embodiment is performed by the thermal barrier coating forming method S100 described below.

In the thermal barrier coating forming method S100, the thermal barrier coating 100 is formed on the bucket body 70. The thermal barrier coating forming method S100 of the present embodiment includes a bond coat layer forming step S110, an overcoat layer forming step (ceramic layer forming step) S120, and an adjustment step S130.

In the bond coat forming step S110, the bond coat 110 is formed on the surface of the rotor blade body 70. The bond coat forming step S110 is performed after the bucket body preparing step S10. In the bond coat forming step S110, for example, spray particles of the MCrAlY alloy are sprayed onto the surface of the blade body 70 using a spray gun. In the bond coat forming step S110, the spray gun is moved so that the spray holes of the spray particles are directed perpendicularly to the surface of the rotor blade body 70. In the bond coat forming step S110 of the present embodiment, the bond coat 110 is formed by High Velocity flame Spraying (HVOF: High Velocity Oxygen Fuel) or Low Pressure Plasma Spraying (LPPS: Low Pressure Plasma Spraying) using a spray gun.

In the overcoat layer forming step S120, an overcoat layer 120 including ceramic is formed on the surface of the rotor blade body 70. The overcoat layer forming step S120 is performed after the bond coat layer forming step S110. In the overcoat layer forming step S120, the overcoat layer 120 is stacked on the bond coat layer 110 formed in the bond coat layer forming step S110. In the overcoat layer forming step S120, a thermal spraying method is used. Therefore, in the overcoat layer forming step S120 of the present embodiment, the overcoat layer 120 is formed by thermal spraying of thermal spraying particles onto the surface of the bond coat layer 110 formed on the rotor blade body 70. The overcoat layer forming step S120 includes a first dense layer forming step S121, a pore layer forming step S122, and a second dense layer forming step S123.

The first dense layer forming step S121 is performed after the adhesive coating layer forming step S110. In the first dense layer forming step S121, the first dense layer 121 is formed on the bond coat layer 110. The first dense layer forming step S121 forms the first dense layer 121 by performing suspension plasma spraying. In the first dense layer forming step S121, the spray gun is tilted at a predetermined tilt angle α with respect to the surface of the rotor blade body 70 to perform the suspension plasma spraying. Suspension plasma spraying is a spraying method in which a suspension in which fine spray particles are dispersed is supplied to a plasma jet to form a coating film. In the first dense layer forming step S121, the distance between the injection hole of the spray gun and the surface of the rotor blade body 70 to be sprayed is shorter than that in the porous layer forming step S122.

The fine sprayed particles preferably have a particle size of 0.1 to 1.0 μm. Examples of the carrier used in the suspension include water and ethanol. For the suspension plasma spraying, a spray gun in which the suspension is supplied to the plasma jet by an axial flow internal supply system may be used, or a spray gun in which the suspension is supplied to the plasma jet by an external supply system may be used.

The pore layer forming step S122 is performed after the first dense layer forming step S121. In the pore layer forming process S122, an intermediate pore layer 122 is formed on the first dense layer 121. The pore layer forming process S122 performs suspension plasma sputtering to form the intermediate pore layer 122. In the porous layer forming step S122, the spray gun is moved farther from the rotor blade body 70 than in the first dense layer forming step S121 to spray the spray particles. In the pore layer forming step S122, first, the spray gun is moved so as to be gradually separated from the movable blade body 70 from the spray distance in the first dense layer forming step S121, and spray is performed. Subsequently, at a time point when the intermediate pore layer 122 is formed to about half of the desired film thickness of the intermediate pore layer 122, the sputtering distance is gradually made closer to the sputtering distance in the second dense layer forming process S123. Finally, at the time point of forming the intermediate pore layer 122 having a desired film thickness, the spray gun is moved so that the spray distance coincides with the spray distance in the second dense layer forming step S123.

The second dense layer forming step S123 is performed after the pore layer forming step S122. In the second dense layer forming process S123, the second dense layer 123 is formed on the intermediate pore layer 122. The second dense layer forming step S123 forms the second dense layer 123 by performing suspension plasma spraying. In the second dense layer forming step S123, the spray gun is brought closer to the rotor blade body 70 than in the air hole layer forming step S122 to spray the spray particles. The second dense layer forming step S123 of the present embodiment is performed under the same conditions as the first dense layer forming step S121. Therefore, in the second dense layer forming step S123, the spray gun is inclined at a predetermined inclination angle α with respect to the surface of the rotor blade body 70, and the spray is performed by the suspension plasma spraying. In the second dense layer forming step S123, the distance between the injection hole of the spray gun and the surface of the movable blade body 70 to be sprayed is shorter than that in the porous layer forming step S122.

The adjusting step S130 is performed after the second dense layer forming step S123. In the adjustment step S130, the state of the surface of the thermal barrier coating 100 is adjusted. Specifically, in the adjustment step S130, the surface of the overcoat layer 120 is slightly cut to adjust the film thickness of the thermal barrier coating 100 or to make the surface smoother. In the adjusting step S130, for example, the heat conductivity to the rotor blade 7 can be reduced. In the adjustment step S130 of this embodiment, the surface of the overcoat layer 120 can be smoothed and the film thickness can be adjusted by cutting the surface of the second dense layer 123 by several μm.

According to the thermal barrier coating 100, the thermal barrier coating forming method S100, and the movable blade 7 as described above, the intermediate gas pore layer 122 is formed between the first dense layer 121 and the second dense layer 123, and the heat input to the overcoat layer 120 in the thickness direction is blocked by the intermediate gas pore layer 122. As a result, the thermal conductivity of the overcoat layer 120 can be further reduced. In the overcoat layer 120, the first dense layer 121 is formed on the side that is in close contact with the rotor blade body 70, that is, the bond coat layer 110, so that the close contact with the bond coat layer 110 can be ensured. Further, in the overcoat layer 120, the second dense layer 123 is formed on the surface side, so that the erosion resistance can be secured. This can improve the heat insulating effect while suppressing a decrease in erosion resistance in the heat insulating coating 100.

specifically, the point that the thermal conductivity is reduced by having the intermediate orifice layer 12 will be described with reference to fig. 5. Fig. 5 is a graph of the relationship between the thermal conductivity and the porosity in the overcoat 120 obtained by simulation. As shown in fig. 5, in the overcoat layer 120, the higher the porosity, the lower the thermal conductivity in the overcoat layer 120. More specifically, when the porosity is increased from 0% to 15%, the thermal conductivity is reduced by about 10%. From this, it is understood that the thermal conductivity in the overcoat layer 120 can be reduced by forming the intermediate pore layer 122 having a high porosity between the first dense layer 121 and the second dense layer 123.

further, by setting the porosity in the intermediate orifice layer 122 to 10% or more and 20% or less, the effect of the first longitudinal crack C1 and the second longitudinal crack C2 on inhibiting heat input in the thickness direction is improved. As a result, the thermal conductivity in topcoat 120 can be substantially reduced without substantially reducing the erosion resistance in intermediate orifice layer 122.

further, as with the first and second longitudinal cracks C1 and C2, the obliquely formed longitudinal cracks C are formed in the overcoat layer 120. Therefore, the heat input in the thickness direction in the first dense layer 121 is hindered by the obliquely extending first longitudinal crack C1. Likewise, the heat input in the thickness direction in the second dense layer 123 is hindered by the obliquely extending second longitudinal crack C2. Therefore, the thermal conductivity in the overcoat layer 120 can be reduced by the first longitudinal crack C1 and the second longitudinal crack C2. On the other hand, a second dense layer 123 is formed on the surface side in the overcoat layer 120. The more the longitudinal cracks C are formed, the more densely the second dense layer 123 is formed, and thus the decrease in erosion resistance can be suppressed. This can improve the heat insulating effect while suppressing a decrease in erosion resistance on the surface side of the thermal barrier coating 100.

specifically, the point that the thermal conductivity is reduced by inclining the longitudinal crack C will be described with reference to fig. 6. Fig. 6 is a graph of the relationship between the thermal conductivity of the overcoat layer 120 having the longitudinal crack C formed thereon and the inclination angle α of the longitudinal crack C, which was obtained by simulation. As shown in fig. 6, in the overcoat layer 120, the smaller the inclination angle α of the longitudinal crack C, the smaller the thermal conductivity in the overcoat layer 120. More specifically, when the inclination angle α of the longitudinal crack C is 60 °, the thermal conductivity is reduced by 25% or more, as compared with the state where the longitudinal crack C is not inclined (the case where the inclination angle α is 90 °). From this, it is understood that the thermal conductivity in the overcoat layer 120 can be reduced by inclining the longitudinal crack C.

Further, since the overcoat layer 120 is formed by the suspension plasma spraying, the particle size of the sprayed particles forming the overcoat layer 120 becomes smaller than that of the Atmospheric Plasma Spraying (APS). As a result, the first dense layer 121 and the second dense layer 123 can have a very fine structure. This can improve the adhesion of the first dense layer 121 to the bond coat layer 110 and the adhesion between the layers in the overcoat layer 120.

Further, the first longitudinal crack C1 and the second longitudinal crack C2 are all inclined in the same direction, and thus heat input in the thickness direction can be inhibited over a wide area in the surface direction of the first dense layer 121 and the second dense layer 123. As a result, the thermal conductivity in overcoat layer 120 can be reduced in a wide range.

the inclination angle α of the first longitudinal crack C1 and the second longitudinal crack C2 is set to 45 ° or more and 80 ° or less. By decreasing the inclination angle α, the effect of the first longitudinal crack C1 and the second longitudinal crack C2 to hinder the heat input in the thickness direction is increased. As a result, the thermal conductivity in the overcoat layer 120 can be significantly reduced. Further, by setting the inclination angle α of the first vertical crack C1 and the second vertical crack C2 to 45 degrees or more, it is possible to suppress the adhesion of the thermally sprayed particles to the surface during the formation of the first dense layer 121 and the second dense layer 123. Therefore, the reduction in the manufacturing efficiency of overcoat layer 120 can be further suppressed.

(other modification of the embodiment)

while the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations thereof in the embodiments are examples, and additions, omissions, substitutions, and other modifications of the configurations can be made without departing from the spirit of the present invention. The present invention is not limited by the embodiments, but is limited only by the technical means.

In the above embodiment, the first longitudinal crack C1 and the second longitudinal crack C2 have an inclined structure, but the overcoat layer 120 is not limited to such a structure. For example, as shown in fig. 7, the overcoat layer 120A of the thermal barrier coating 100A having a structure in which the longitudinal cracks C (non-inclined longitudinal cracks) extending perpendicularly to the plane direction may be formed. Therefore, the first longitudinal crack C1 of the first dense layer 121A and the second longitudinal crack C2 of the second dense layer 123A extend in the perpendicular direction with respect to the surface of the overcoat layer 120A.

In the above embodiment, overcoat 120 has a multilayer structure in which intermediate pore layer 122 is formed between first dense layer 121 and second dense layer 123. However, overcoat 120 is not limited to such a structure. For example, as shown in fig. 8, the outer coating layer 120A of the thermal barrier coating 100A may also be formed in a single-layer structure having inclined longitudinal cracks C.

In the thermal barrier coating layer forming method S100 according to the present embodiment, the bond coat layer forming step S110 may not be performed. For example, in other methods, the bond coat 110 may or may not be formed, and the bond coat 110 itself may or may not be formed. The ceramic layer may be formed directly on the surface of the blade body 70 without forming the bond coat 110.

The high-temperature member is not limited to the rotor blade 7, and may be a member exposed to a high temperature. The present invention can be applied to high-temperature components, such as the vanes 8 of the gas turbine 1, the nozzles constituting the combustor 3, and the cylinder. The high-temperature component may be a component exposed to high temperature other than the gas turbine 1. For example, the high temperature component may be a component exposed to a high temperature environment in a gas engine.

The intermediate pore layer 122 is not limited to a structure in which no longitudinal crack C is formed at all but only the pores P are formed. The intermediate orifice layer 122 may be slightly formed with longitudinal cracks C as long as its porosity is sufficiently large. Similarly, the first dense layer 121 and the second dense layer 123 may have a slight amount of pores P as long as the longitudinal cracks C are formed.

the extending direction of the longitudinal crack such as the first longitudinal crack C1 and the second longitudinal crack C2 is not limited to the extending direction of the virtual straight line connecting the base end and the tip end as described above. The extending direction of the longitudinal crack may be obtained by image analysis or the like from a complicated longitudinal crack, and the extending direction of the approximate straight line may be adopted.

The first and second longitudinal cracks C1 and C2 may be inclined, and are not limited to being inclined in the same direction over the entire region. The inclination angle α of the longitudinal crack C may be different on the surface side of the ceramic layer from that on the blade body 70 side. That is, the longitudinal cracks may be inclined at different angles in the middle of the extending direction, for example, as long as they are inclined in the same direction. Therefore, for the first longitudinal crack C1 and the second longitudinal crack C2, for example, the inclination angle α in the region on the side close to the surface of the outer coating 120 may be formed smaller than the inclination angle α in the region on the side close to the surface of the bucket body 70.

In the present embodiment, the inclination angles α of the first longitudinal crack C1 of the first dense layer 121 and the second longitudinal crack C2 of the second dense layer 123 are the same, but the first dense layer 121 and the second dense layer 123 are not limited to such a structure. Thus, the angle of inclination α of the first longitudinal crack C1 relative to the surface of the overcoat 120 may be different from the angle of inclination α of the second longitudinal crack C2 relative to the surface of the overcoat 120. At this time, the inclination angle α of the first longitudinal crack C1 is preferably smaller than the inclination angle α of the second longitudinal crack C2.

In the present embodiment, the distribution ratios of the longitudinal cracks C per 1mm of the first dense layer 121 and the second dense layer 123 are set to be the same, but the first dense layer 121 and the second dense layer 123 are not limited to such a configuration. For example, the distribution rate of the longitudinal cracks C per 1mm of the second dense layer 123 may be greater than the distribution rate of the longitudinal cracks C per 1mm of the first dense layer 121, or may be less than the distribution rate of the longitudinal cracks C per 1mm of the first dense layer 121.

in the present embodiment, the porosity of the first dense layer 121 and the porosity of the second dense layer 123 are the same, but the first dense layer 121 and the second dense layer 123 are not limited to such a configuration. For example, the porosity of the first dense layer 121 and the porosity of the second dense layer 123 may be different from each other as long as they are lower than the porosity of the intermediate pore layer 122.

In addition, as for the longitudinal crack C of the present embodiment, like the first longitudinal crack C1 and the second longitudinal crack C2, in one overcoat layer 120, a space is provided in the vicinity of the middle in the thickness direction by the intermediate pore layer 122. In this way, the longitudinal crack C is not limited to a structure that continues from the side of the ceramic layer facing the blade body 70 to the surface. Therefore, the longitudinal cracks C may intermittently extend in the thickness direction within one ceramic layer. Therefore, the first longitudinal crack C1 and the second longitudinal crack C2 are not limited to the continuously extending structure as shown in the present embodiment. For example, the first longitudinal cracks C1 may be formed at intervals in the thickness direction within the first dense layer 121. Likewise, the second longitudinal cracks C2 may be formed at intervals in the thickness direction within the second dense layer 123.

In the pore layer forming step S122 of the present embodiment, the spray gun is moved so that the spray distance is gradually changed (changed), but the movement of the spray gun is not limited to this. For example, in the pore layer forming step S122, the spray gun may be moved so as to abruptly change from the spraying distance in the first dense layer forming step S121 to the target spraying distance in the pore layer forming step S122.

The thermal spraying conditions in the respective steps are examples, and are not limited to these. The conditions for thermal spraying may be set appropriately according to the apparatus used, the type of particles to be sprayed, and the like.

Industrial applicability

The present invention can be applied to a method for forming a thermal barrier coating, and a high-temperature member, and can improve a thermal insulation effect while suppressing a decrease in erosion resistance.

Description of reference numerals:

1 … gas turbine; 2 … compressor; 3 … burner; 4 … turbine body; 5 … rotor; 6 … outer shell; 7 … bucket; 70 … bucket body; 71 … blade body portion; 72 … platform section; 73 … root of leaf; 74 … cover shield portion; 8 … stationary vanes; a … compressed air; g … combustion gas; 100 … thermal barrier coating; 110 … bond coat; 120 … outer coating; 121 … first dense layer; c1 … first longitudinal crack; α … tilt angle; 122 … intermediate gas orifice layer; a P … vent; 123 … second dense layer; c2 … second longitudinal crack; s1 … a method for manufacturing a high-temperature member; s10 … a bucket body preparation step; s20 … a thermal barrier coating forming step; s100 … thermal barrier coating forming method; s110 … bond coat forming step; s120 … overcoat layer forming step; s121 … a first dense layer forming step; s122 … pore layer forming step; s123 … a second dense layer forming step; s130 … adjustment step; c … longitudinal crack.