JP7122926B2 - Method for manufacturing turbine components - Google Patents

Description

The present invention relates to a method for manufacturing turbine components .

Among the plurality of parts that make up a turbine, in recent years, studies have been made on a method of manufacturing parts that come into contact with a high-temperature working medium by a three-dimensional additive manufacturing method in order to increase the dimensional accuracy of the product.

For example, in the manufacturing method described in Patent Document 1 below, a step of forming an alloy base material by a three-dimensional additive manufacturing method or the like, and a heat treatment step for enlarging the crystal grains of this base material are performed. Run.

JP 2017-214909 A

After forming a base material by a three-dimensional additive manufacturing method, if the base material is subjected to heat treatment as described in the above-mentioned Patent Document 1, a plurality of defects are generated in the base material. In particular, multiple defects that open on the surface of the substrate can reduce the durability of the substrate.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for manufacturing a turbine component that can suppress deterioration in durability even when heat treatment is applied to the base material after the base material is formed by the three-dimensional additive manufacturing method. and

A method for manufacturing a turbine component according to one aspect of the present invention includes a substrate forming step of forming an alloy substrate by an additive manufacturing method; A sealing treatment step of forming a metal oxide layer on the surface of the material, and a heat treatment step of performing a heat treatment for coarsening the crystal grains of the base material after the sealing treatment. do.

When subjected to heat treatment, defects due to partial melting may be formed on the surface of the substrate. Defects that open on the surface lead to a decrease in the strength of the base material. However, in this embodiment, a film is formed on the surface of the base material by performing the pore-sealing treatment by the sol-gel method, and the film can close the openings on the surface of the base material that existed before the heat treatment. As a result, in this aspect, it is possible to suppress the occurrence of open defects on the substrate surface.

Here, in the turbine component manufacturing method of the aspect, the alloy may be a Ni-based alloy or a Co-based alloy.

According to this aspect, it is possible to provide a turbine component with higher durability.

In any one of the turbine component manufacturing methods described above, the sol used in the sol-gel method may contain an organic solvent and an organometallic solute.

According to this aspect, when the sealing treatment is performed, first, the sol containing the organic solvent and the organometallic solute is gelled on the surface of the substrate. Evaporation of the organic solvent from the gel retains the organometallic solute on the surface of the substrate. Furthermore, even when a hydrophobic substance is used as the organometallic solute, the presence of an organic solvent increases the affinity between water and the organometallic solute, and a homogeneous sol can be obtained.

In any one of the turbine component manufacturing methods described above, the organometallic solute may include at least one of Si, YSZ, Al, and Ti.

According to this aspect, since at least one of Si, YSZ, Al, and Ti is contained as the organometallic solute, stronger and more stable oxidation can be achieved when the pore-sealing treatment is performed. A metal layer can be formed.

Further, in the method for manufacturing a turbine component according to any one of the above aspects, a hot isostatic pressurization process may be performed for subjecting the base material after the heat treatment to a hot isostatic pressurization process. .

According to this aspect, even if defects occur inside the base material due to partial melting that occurs during the heat treatment, such defects are compressed and eliminated by performing the hot isostatic pressing treatment. As a result, the durability of the substrate can be further enhanced.

In the turbine component manufacturing method according to the above aspect, in which the hot isostatic pressing process is performed, the base material after the hot isostatic pressing process is subjected to a solution treatment or an aging treatment; A stripping step of stripping the metal oxide layer from a part of the surface of the base material that has been solution treated or aged; and a thermal barrier coating layer forming step of forming a thermal coating layer. In this case, the thermal barrier coating layer includes a metal-containing bond coat layer formed on the surface of the part of the base material after the peeling step, and a metal oxide bond coat layer formed on the surface of the bond coat layer. and a topcoat layer.

According to this aspect, the solution treatment or aging treatment is applied to the base material after the hot isostatic pressing treatment, so that the non-coherent phase in the crystal of the base material is dissolved and the coherent phase is formed. Precipitate. Thereby, the strength and durability of the substrate can be further enhanced. Furthermore, by performing the peeling step before the thermal barrier coating layer forming step, the metal oxide layer is peeled off from the surface of the base material, so that the bond coat layer can be better attached to the surface of the base material. . By forming a metal oxide top coat layer on the bond coat layer, the substrate surface can be protected from high temperatures during operation.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the turbine component which can suppress deterioration in durability even if it heat-processes can be provided.

1 is a schematic diagram showing the configuration of a gas turbine according to an embodiment of the present invention; FIG. 1 is an enlarged cross-sectional view of a main part of a gas turbine according to an embodiment of the invention; FIG. 1 is a cross-sectional view showing the configuration of a turbine component (base material) according to an embodiment of the present invention; FIG. FIG. 4 is a process diagram showing steps of a method for manufacturing a turbine component according to an embodiment of the present invention; 1 is a schematic diagram showing the configuration of a turbine component (base material) according to an embodiment of the present invention; FIG. FIG. 4 is an explanatory view showing the turbine component (base material) during the sealing treatment process according to the embodiment of the present invention; FIG. 4 is a cross-sectional view showing the configuration of the turbine component (base material) after the sealing treatment process according to the embodiment of the present invention; FIG. 4 is an enlarged cross-sectional view showing the state of the surface of the turbine component (base material) after the sealing treatment process according to the embodiment of the present invention; FIG. 4 is a cross-sectional view showing the configuration of the turbine component (base material) after the peeling process according to the embodiment of the present invention; 1 is a cross-sectional view showing the configuration of a turbine component (base material) according to an embodiment of the present invention, and is a cross-sectional view after forming a bond coat layer; FIG.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a gas turbine 1 according to this embodiment. The gas turbine 1 includes a compressor 2 that compresses combustion air A, a combustor 3 that injects and burns fuel into the compressed air supplied from the compressor 2 to generate combustion gas FG, and a combustor 3. a turbine 4 driven by the combustion gases FG from the . The compressor 2 has a compressor rotor rotating about an axis and a compressor casing. The turbine 4 has a turbine rotor rotating about an axis and a turbine casing. The compressor rotor and the turbine rotor are positioned on the same axis and connected to each other to form a gas turbine rotor 5 . For example, a generator 6 is connected to the gas turbine rotor 5 .

FIG. 2 is a cross-sectional view showing part of the turbine 4. As shown in FIG. As described above, the turbine 4 includes a turbine rotor 5t and a turbine casing 10 covering the turbine rotor 5t. The turbine rotor 5t has a rotor shaft portion 5ta that rotates about the axis Ar, and a plurality of turbine rotor blades 8 arranged around the rotor shaft portion 5ta. A plurality of turbine rotor blades 8 are arranged in a circumferential direction with respect to the axis Ar. The turbine 4 further includes a plurality of turbine stator vanes 7 and a plurality of split rings 9 . The plurality of turbine stationary blades 7 are arranged in the circumferential direction with respect to the axis Ar, arranged axially upstream of the plurality of turbine rotor blades 8 , and fixed to the turbine casing 10 . The plurality of split rings 9 are arranged in the circumferential direction with respect to the axis Ar and form a ring as a whole. The plurality of split rings 9 are arranged radially outside the plurality of turbine rotor blades 8 . A gap is provided between the split ring 9 and the tip of the turbine rotor blade 8 .

In the following description, members of the gas turbine 1 are appropriately referred to as turbine components 20 . The turbine component 20 is a high temperature component (high temperature member) exposed to high temperature combustion gas FG. Turbine component 20 may be a member of turbine 4 or a member of combustor 3 . The turbine component 20 may be the turbine stationary blade 7 , the turbine rotor blade 8 , or the split ring 9 .

FIG. 3 is a schematic cross-sectional view showing the configuration of the turbine component 20. As shown in FIG. As shown in the figure, the turbine component 20 has a base material B, a first metal oxide layer L1, a bond coat layer Lb, and a second metal oxide layer L2 (top coat layer).

The base material B is made of, for example, a Ni-based alloy or a Co-based alloy. This base material B is manufactured by a layered manufacturing method using a 3D printer. In this method, a powdered alloy is sequentially melted by laser irradiation to obtain a desired shape.

Inside the base material B, for example, a space as a cooling flow path F is formed. Cooling air for cooling the turbine component 20 from the inside during operation of the gas turbine 1 flows through the cooling flow path F. In addition, in FIG. 3, the shape of this cooling flow path F is represented typically.

A first metal oxide layer L1 is formed on the wall surface of the cooling channel F, which is part of the surface of the base material B. As shown in FIG. The first metal oxide layer L1 is a thin film layer that covers the entire wall surface of the cooling channel F. As shown in FIG. The first metal oxide layer L1 is made of a metal material containing at least one of Si, YSZ, Al, and Ti. The first metal oxide layer L1 is formed by a sealing treatment step S2, which will be described later.

A thermal barrier coating (TBC) layer L3 is formed on another portion of the surface of the base material B, ie, a portion different from the cooling flow path F described above. In the example of FIG. 3, the thermal barrier coating layer L3 is formed on the portion of the surface of the turbine component 20 that is exposed to the outside. The thermal barrier coating layer L3 is provided to protect the turbine component 20 from the high temperature of combustion gas during operation of the gas turbine 1 .

The thermal barrier coating layer L3 has a bond coat layer Lb covering the surface of the substrate B, and a second metal oxide layer (top coat layer) L2 formed on the bond coat layer Lb. The bond coat layer Lb is provided to hold the second metal oxide layer L2 in close contact with the surface of the substrate B. As shown in FIG. In forming the bond coat layer Lb, an aerosol deposition method is used as an example. The bond coat layer Lb has a base material made of, for example, rare earth silicate. Rare earth silicates are silicon compounds containing rare earth elements such as yttrium, scandium, cerium, neodymium and ytterbium. As the rare earth silicate, Ln2Si2O7, Ln2SiO5, and a mixed phase of Ln2Si2O7 and Ln2SiO5 are preferably used. The bond coat layer Lb exemplified above is called a Si bond coat layer. The bond code layer includes a metal bond coat layer in addition to this Si bond coat layer. The metal bond coat layer is made of, for example, an MCrAlY alloy (M is Co, Ni, or a combination thereof).

The second metal oxide layer (top coat layer) L2 is formed by spraying metal oxide powder onto the bond coat layer Lb. A rare earth silicate can be used as the base material of the second metal oxide layer L2. The second metal oxide layer L2 may be formed using a ZrO2-based material, and may include YSZ (yttria-stabilized zirconia), which is ZrO2 partially or fully stabilized with Y2O3. By forming the thermal barrier coating layer L3 as described above on the surface of the base material B, the environmental resistance and heat resistance of the base material B can be improved. That is, the thermal barrier coating layer L3 having the structure as described above has higher heat resistance, airtightness, and oxidation resistance than the substrate B itself.

The thickness of the first metal oxide layer L1 is 1/10 or less of the thickness of the second metal oxide layer L2. Specifically, the thickness of the second metal oxide layer L2 is 300 to 700 μm, while the thickness of the first metal oxide layer L1 is 1 to 5 μm. Since the second metal oxide layer L2 is a layer for protecting the substrate B from the high-temperature combustion gas FG, it must have a certain thickness or more. On the other hand, as will be described later, the first metal oxide layer L1 is a layer for blocking openings of a plurality of defects occurring on the surface of the base material B. Thinner is preferred. Therefore, as explained above, the thickness of the first metal oxide layer L1 is much thinner than the thickness of the second metal oxide layer L2.

Next, a method for manufacturing a turbine component according to this embodiment will be described with reference to FIG. As shown in the figure, this manufacturing method includes a substrate forming step S1, a sealing treatment step S2, a heat treatment step S3, a HIP treatment step S4, a solution treatment/aging treatment step S5, and an oxide film peeling step. S6, and a TBC forming step S7.

In the base material forming step S1, the base material B of the turbine component 20 having desired shape and dimensions is formed. As described above, in this step, as shown in FIG. 5, the substrate B is formed from the powdered alloy by the layered manufacturing method using a 3D printer. Inside the base material B, a cooling flow path F is formed.

A sealing treatment step S2 is performed after the base material forming step S1. In the pore-sealing step S2, the substrate B is subjected to pore-sealing treatment by a sol-gel method. The pore-sealing step S2 includes an immersion step S21 and a drying step S22. As shown in FIG. 6, in the immersion step S21, the substrate B is immersed in a sol So prepared in advance. A solution containing an organic solvent and an organometallic solute is used as the sol. More specifically, the sol contains 99% ethanol as an organic solvent, an alkoxide as an organometallic solute, distilled water (water), and 2N hydrochloric acid (or 1.5N aqueous ammonia). Note that N is the normality. More specifically, tetraethoxysilane (containing Si element) is used as the alkoxide. In obtaining the sol, it is desirable to mix 99% ethanol, tetraethoxysilane, and 2N hydrochloric acid (or 1.5N aqueous ammonia) at a volume ratio of 10:10:3. In such a solution, alkoxide (tetraethoxysilane) is hydrolyzed with 2N hydrochloric acid (or 1.5N aqueous ammonia as a catalyst. Hydrolysis of alkoxide is a reaction in which alkoxyl groups are substituted with hydroxyl groups. Furthermore, a dehydration condensation reaction occurs between the hydrolyzed chemical species in the solution, resulting in the formation of an inorganic polymer (metalloxane polymer) having a metalloxane bond as a skeleton in the solution. The organometallic solute mentioned above is not limited to tetraethoxysilane, and may contain at least one of Si, YSZ, Al and Ti.

The entire substrate B is immersed in the above sol. As a result, the sol adheres to the entire surface of the substrate B, including the wall surfaces of the cooling channels F. As shown in FIG. After that, the substrate B is pulled up from the sol at a constant speed. At this time, ethanol, which is an organic solvent, evaporates from the sol on the surface of the substrate B and gels in the portion of the sol exposed to the air. That is, as shown in FIG. 7, the fluidity of the sol is lowered, and the sol is retained on the surface of the substrate B as a gel g. In the above description, the substrate B is immersed in the previously prepared sol So, but instead of this, the substrate B may be coated with the previously prepared sol So. That is, in this step, the sol So prepared in advance may be adhered to the entire surface of the base material B.

After the immersion step S21, a drying process is performed on the substrate B to which the gel film is attached (drying step S22). In the drying step S22, the gel film is rapidly heated by, for example, putting the substrate B into an electric furnace at a high temperature (eg, a temperature of 500° C. or higher). It is said that rapid heating in this way is less likely to cause cracks or peeling of the gel film than to slowly raise the temperature of the gel film. By heating the gel, the organic solvent (eg, ethanol) remaining in the gel is first evaporated. Thereafter, a condensation reaction proceeds between the hydroxyl groups remaining in the metalloxane polymer described above, and a combustion reaction occurs between the alkoxyl groups and oxygen in the air. As a result, a layer derived from at least one of Si, YSZ, Al, and Ti contained in the tetraethoxysilane, that is, the above-described first metal oxide layer L1 is formed on the surface of the substrate B. be done.

By performing such a pore-sealing treatment, as schematically shown in FIG. 8, the defects D with fine openings H existing on the surface of the substrate B are sealed.

After the drying step S22, the heat treatment step S3 is performed. In the heat treatment step S3, the substrate B with the first metal oxide layer L1 formed thereon is heated, for example, in an atmosphere of 1250 to 1350° C. for 1.5 to 24 hours. Preferably, substrate B is heated in an atmosphere of 1290-1310° C. for 2 hours. Due to this heat treatment, the crystal grains of the alloy constituting the base material B are coarsened. Thereby, the creep strength of the base material B is increased compared to before the heat treatment. When the heat treatment step S3 is performed, partial melting occurs at the crystal grain boundary of the base material B and the co-crystal portion in the vicinity thereof, so that defects are formed to a certain extent.

After the heat treatment step S3, a HIP (Hot Isostatic Pressing) treatment step S4 is performed. The HIP treatment step S4 is performed to eliminate defects due to the above partial melting. In the HIP treatment step S4, an isotropic pressure of several 10 to 200 MPa is applied to the base material B after the heat treatment under a high temperature of several 100 to 2000° C., for example. As an example, pressure treatment is performed in a high-temperature vessel filled with a stable gas such as argon as a pressure medium. By performing this HIP treatment, defects generated inside the base material B are eliminated or reduced. In addition, when the defect which opens in the surface of the base material B has arisen, it is difficult to eliminate the said defect in HIP processing process S4. However, in this embodiment, the defect having the opening is previously sealed with the first metal oxide layer L1 as described above. As a result, the substrate B that has undergone the HIP treatment step S4 has no or very few defects inside and on the surface.

Next, the solution treatment/aging treatment step S5 is performed. In this step, the substrate B after the HIP treatment is heated again. Specifically, first, the incoherent phase (incoherent γ' phase) in the crystal of the base material B is dissolved by the solution treatment. Furthermore, a coherent phase (coherent γ' phase) is precipitated by performing an aging treatment. When performing the aging treatment, it is desirable to precipitate 30% by volume or more of the coherent γ' phase at 700°C. The high-temperature strength of the base material B is increased by performing the solution treatment/aging treatment step S5.

Subsequently, an oxide film peeling step S6 (peeling step) is performed. In this step, the above-described first metal oxide layer L1 is removed (peeled off) by blasting the base material B after solution treatment and aging treatment. More specifically, in the blasting process, fine metal particles are made to collide with the surface of the substrate B at high speed to remove the first metal oxide layer L1. By performing this blasting treatment, the first metal oxide layer L1 is removed only from a portion of the surface exposed to the outside, except for the wall surfaces of the cooling channels F formed inside the base material B. In other words, as shown in FIG. 9, the first metal oxide layer L1 remains only on the wall surfaces of the cooling channels F among the entire surface of the base material B. As shown in FIG. Note that even in this state, defects with openings occurring on the surface remain sealed by the first metal oxide layer L1.

After the oxide film stripping step S6, a TBC forming step S7 is performed. In this step, the thermal barrier coating layer L3 (TBC layer) described above is formed on part of the surface of the substrate B. As shown in FIG. Specifically, as shown in FIG. 10, the bond coat layer Lb is formed on the portion of the surface of the substrate B that is exposed to the outside. After that, the second metal oxide layer L2 is formed by spraying metal oxide powder onto the bond coat layer Lb.

Through the above processing, the turbine component 20 having the configuration shown in FIG. 3 is formed.

Here, as in the present embodiment, if the base material B is formed by the three-dimensional additive manufacturing method and then heat-treated, the base material B will have a plurality of defects. In particular, if a plurality of open defects occur on the surface of the base material B, the durability of the base material B may decrease. However, according to the above-described method, a film (first metal oxide layer L1) is formed on the surface of the base material B by performing a pore-sealing treatment in advance by the sol-gel method, and the film exists before the heat treatment. The opening on the surface of the base material B can be closed. That is, defects with openings that are difficult to disappear in the subsequent HIP process can be sealed by the sealing process. As a result, durability of the turbine component 20 can be improved.

Furthermore, since the base material B is a Ni-based alloy or a Co-based alloy, it is possible to provide the turbine component 20 with higher durability.

In addition, in the method described above, the sol used for the sealing treatment contains an organic solvent, an organometallic solute, and water. As a result, the organometallic solute is first gelled on the surface of the substrate B when the sealing treatment is performed. The organometallic solute is retained on the surface of the substrate B by evaporation of the organic solvent from the gelled organometallic solute. Furthermore, even when a hydrophobic substance is used as the organometallic solute, the presence of an organic solvent increases the affinity between water and the organometallic solute, and a homogeneous sol can be obtained. As a result, the sealing process can be stably performed.

Furthermore, according to the above-described method, since at least one of Si, YSZ, Al, and Ti is contained as the organometallic solute, when the pore-sealing treatment is performed, the And a stable metal oxide layer can be formed.

Furthermore, according to the above-described method, the hot isostatic pressing treatment step of performing the HIP treatment is performed on the base material B after the heat treatment. As a result, even if defects occur inside the base material B due to partial melting during heat treatment, such defects are compressed and eliminated by performing the hot isostatic pressing process. As a result, the durability of the base material B can be further enhanced.

In addition, according to the above method, the solution treatment or aging treatment is applied to the base material B after the hot isostatic pressing treatment, so that the incoherent phase in the crystal of the base material B becomes a solid solution. At the same time, a coherent phase precipitates. Thereby, the strength and durability of the base material B can be further enhanced. Furthermore, by performing the peeling step before the thermal barrier coating layer L3 forming step, the metal oxide layer is peeled off from the surface of the base material B, so that the bond coat layer Lb can be firmly attached to the surface of the base material B. can do. By forming the metal oxide top coat layer on the bond coat layer Lb, the surface of the substrate B can be protected from high temperatures during operation.

Furthermore, according to the above configuration, in the turbine component 20, since the first metal oxide layer L1 is formed, even if a defect with an opening occurs on the surface of the base material B, it can be sealed. can be stopped. As a result, the durability of the base material B can be improved. Furthermore, since the bond coat layer Lb and the second metal oxide layer L2 are formed on a part of the surface of the substrate B that is different from the part on which the first metal oxide layer L1 is formed, the turbine component is in operation. The turbine components can be thermally protected even when exposed to high temperatures of .

The embodiments of the present invention have been described above. It should be noted that various changes and modifications can be made to the above configuration and method without departing from the gist of the present invention. For example, the ratio and volume of each component of the sol used in the sealing treatment step S2 described in the above embodiment are examples, and can be changed as appropriate depending on the dimensions and physical properties of the substrate B and environmental conditions.

Reference Signs List 1 Gas turbine 2 Compressor 3 Combustor 4 Turbine 5 Gas turbine rotor 5t Turbine rotor 5ta Rotor shaft 6 Generator 7 Turbine stator blade 8 Turbine rotor blade 9 Split ring 10 Turbine Casing 20 Turbine component B Base material L1 First metal oxide layer Lb Bond coat layer L2 Second metal oxide layer (top coat layer)
F... Cooling channel g... Gel L3... Thermal barrier coating layer S1... Base material formation process S2... Pore sealing process S3... Heat treatment process S4... HIP treatment process S5... Solution treatment/aging treatment process S6... Oxide film stripping process S7 ... TBC forming step S21 ... Immersion step S22 ... Drying step

Claims (6)

A substrate forming step of forming an alloy substrate by an additive manufacturing method;
A pore-sealing treatment step of applying a sol-gel method to the base material to form a metal oxide layer on the surface of the base material;
a heat treatment step of subjecting the substrate after the sealing treatment to a heat treatment for coarsening the crystal grains of the substrate;
A method of manufacturing a turbine component that performs a A method of manufacturing a turbine component according to claim 1, comprising:
The alloy is a Ni-based alloy or a Co-based alloy,
A method of manufacturing a turbine component. A method for manufacturing a turbine component according to claim 1 or 2,
The sol used in the sol-gel method contains an organic solvent and an organometallic solute.
A method of manufacturing a turbine component. A method of manufacturing a turbine component according to claim 3, wherein
The organometallic solute includes at least one substance selected from Si, YSZ, Al, and Ti.
A method of manufacturing a turbine component. A method for manufacturing a turbine component according to any one of claims 1 to 4,
Performing a hot isostatic pressing treatment step of subjecting the base material after the heat treatment to a hot isostatic pressing treatment,
A method of manufacturing a turbine component. A method of manufacturing a turbine component according to claim 5, wherein
a step of subjecting the base material after the hot isostatic pressing treatment to a solution treatment or an aging treatment;
A stripping step of stripping the metal oxide layer from a part of the solution-treated or aged-treated surface of the substrate;
a thermal barrier coating layer forming step of forming a thermal barrier coating layer on the partial surface of the base material after the peeling step;
and run
The thermal barrier coating layer includes a metal-containing bond coat layer formed on the surface of the part of the base material after the peeling step, and a metal oxide top coat layer formed on the surface of the bond coat layer. and having
A method of manufacturing a turbine component.

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