JP2009293058A - Ceramic laminate, and structure for thermal barrier coating - Google Patents

Abstract

The present invention provides a novel ceramic laminate that has good heat shielding properties, thermal shock resistance, and oxygen barrier properties, and that suppresses interfacial delamination between layers.
A ceramic laminate 2 has a relative density of 95% or more on a first ceramic film 13 having a relative density of 95% or less and a relative density higher than the relative density of the first ceramic film 13. A second ceramic film 15 having a density is laminated. The second ceramic film 15 is preferably formed by an aerosol deposition method. According to the present invention, the ceramic laminate 2 having a structure in which at least a part of the second ceramic film 15 exists on the surface of the first ceramic film 13 can be provided.
[Selection] Figure 1

Description

  The present invention relates to a ceramic laminate and a thermal barrier coating structure for protecting a substrate from heat.

  In aircraft jet engines, power generation gas turbines, and the like, the combustion gas temperature is being increased in order to improve thermal efficiency and output. Accordingly, along with a cooling technique for cooling a member used in a high-temperature environment and further a high-temperature and high-corrosion environment, a thermal barrier coating (TBC) technique for protecting the member from heat becomes important.

  The thermal barrier coating is applied on a metal base material composed of members such as a gas turbine combustor and a moving blade. Generally, its structure is a metal bonding layer (bond coat layer) excellent in environmental resistance, It has a laminated structure with a low thermal conductive ceramic thermal barrier layer (topcoat layer). By providing a ceramic heat shield layer with low thermal conductivity on the combustion gas flow path side, it is possible to extend the life without exposing the metal substrate to a high temperature. Conventionally, a porous ceramic film has been used as the ceramic heat shield layer because of its good heat shield and thermal shock resistance.

  As described in Patent Document 1 and the like, conventionally, a plasma sprayed coating has been widely used as a ceramic thermal barrier layer. FIG. 7 shows a cross-sectional photograph of the thermal barrier coating structure described in FIG. The thermal barrier coating structure 101 has a laminated structure of a metal bonding layer 112 formed on a metal substrate 111 and a ceramic thermal barrier layer 114 made of a sprayed coating.

On the other hand, as described in Non-Patent Document 1 and the like, in recent years, an EB-PVD (electron beam vapor deposition) film has been used as a ceramic thermal barrier layer for a turbine blade of a jet engine. FIG. 8 shows a cross-sectional photograph of the thermal barrier coating structure described in Non-Patent Document 1. This thermal barrier coating structure 102 has a laminated structure of a metal bonding layer 123 formed on a metal substrate 121 and a ceramic thermal barrier layer 124 made of an EB-PVD film. In the thermal barrier coating structure 102, a diffusion layer 122 is formed between the metal substrate 121 and the metal bonding layer 123.
Japanese Unexamined Patent Publication No. 2006-117975 Ishikawajima Harima Technical Report Vol.47 No.1 (2007-3)

  In the thermal spray coating described in Patent Document 1, a large number of pores exist in the coating, thereby exhibiting heat shielding properties and thermal shock resistance. However, many pores are often communicated with each other in the thermal spray coating, and a through-hole penetrating the thermal barrier layer is formed from the surface of the thermal barrier layer to the surface of the metal bonding layer as a base. Not a few.

  In FIG. 7, at first glance, it seems that many pores formed in the sprayed coating are independent from each other, but in reality, many fine pores are also formed in the portion that looks fine. In fact, if a laminated structure consisting of a metal substrate / metal bonding layer / sprayed coating is left immersed in water, rust will form on the surface of the metal bonding layer. Has been confirmed to be formed.

  In a structure in which a through hole that substantially penetrates the heat shield layer is formed, the metal bonding layer comes into contact with the outside air through the through hole, so that the heat shield effect is reduced accordingly. Further, since oxygen gas in the outside air reaches the surface of the metal bonding layer through the through hole, a metal oxide (TGO) is generated on the surface of the metal bonding layer, and this TGO grows, whereby the heat shielding layer. There is also a possibility that interfacial peeling occurs between the metal and the metal bonding layer.

In order to solve the above problem, in Patent Document 1, an oxygen barrier made of a dense Al ₂ O ₃ film or the like is formed between a metal bonding layer and a ceramic heat shield layer by a sol-gel method or a slurry method that is a wet method. It has been proposed to provide a layer (reference numeral 113 in FIG. 7). It is also conceivable to form the oxygen barrier layer by a normal vapor deposition method. However, in general, an oxygen barrier layer formed by a wet method such as a sol-gel method or a slurry method, or a normal vapor phase film formation method does not have good adhesion to the base, and can withstand repeated thermal shocks. There is a risk that interfacial peeling may occur.

  As shown in FIG. 8, the EB-PVD film described in Non-Patent Document 1 has a columnar structure composed of a large number of columnar crystals extending in a direction substantially perpendicular to the substrate surface. In such a structure, there are voids between the columnar crystals adjacent to each other, thereby exhibiting heat shielding properties and thermal shock resistance. However, this void is a through-hole penetrating the heat shield layer from the surface of the heat shield layer to the surface of the metal bonding layer as the base, and the situation is not different from that of the thermal spray coating.

  Although the use and purpose differ, conventionally, sealing treatment has been performed on the sprayed film. As a sealing treatment for the sprayed film, a process of brushing or spraying a sealing paint whose viscosity is appropriately adjusted to the sprayed film, a process of immersing the sprayed film in the sealing paint, For example, a treatment for applying a powdery sealing paint. Such sealing treatment is performed for the purpose of improving the corrosion resistance of the sprayed film.

In order to improve the oxygen barrier property of the ceramic thermal barrier layer, it is conceivable to apply the above-described sealing treatment to a thermal barrier coating structure. However, the sealing paint has a low heat resistance and cannot be used in a thermal barrier coating structure. In addition, as shown in FIG. 9, the sealing paint enters the inside of the sprayed film and fills the pores, so that the thermal insulation and thermal shock resistance of the ceramic thermal insulation layer are also impaired.
FIG. 9 is an image cross-sectional view when the conventional sealing process is performed on the sprayed film 114. In FIG. 9, the left figure shows before the sealing process, and the right figure shows after the sealing process. In the figure, reference numeral 114p indicates pores of the sprayed film 114, and reference numeral 115 indicates sealing paint.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a novel ceramic laminate that has good heat shielding properties, thermal shock resistance, and oxygen barrier properties, and that suppresses interfacial delamination between layers. To do.
It is another object of the present invention to provide a novel thermal barrier coating structure that has good thermal barrier properties, thermal shock resistance, and oxygen barrier properties and that suppresses interfacial delamination between layers.

The ceramic laminate of the present invention is
On the first ceramic film having a relative density of 95% or less,
A second ceramic film having a relative density of 95% or higher and a relative density higher than that of the first ceramic film is laminated.

“Relative density” represents the ratio of the actually measured density to the theoretical density, and is expressed by the following equation.
Relative density = (actual density / theoretical density) × 100 (%)
The actually measured density can be measured by the Archimedes method. As a measuring device, for example, SD200L manufactured by AlfaMirage can be used.

The present invention can provide a ceramic laminate having a structure in which at least a part of the second ceramic film is present on the surface of the first ceramic film.
The second ceramic film is preferably formed by an aerosol deposition method.
Examples of the first ceramic film include those formed by plasma spraying or electron beam evaporation.

When used for applications such as a thermal barrier coating structure, in the ceramic laminate of the present invention, the first ceramic film is at least one selected from the group of Al ₂ O ₃ , HfO ₂ , CeO ₂ , and ZrO _2. Including oxide ceramics
The second ceramic film preferably contains at least one oxide ceramic selected from the group consisting of Al ₂ O ₃ , HfO ₂ , CeO ₂ , and ZrO ₂ .

The thermal barrier coating structure of the present invention is
In a thermal barrier coating structure for protecting a metal substrate from heat,
The metal base layer side has a structure in which a metal bonding layer, a ceramic heat shield layer, and a sealing layer are sequentially laminated,
The laminate of the ceramic heat shield layer and the sealing layer is formed of the ceramic laminate of the present invention.

In the thermal barrier coating structure of the present invention,
The metal base material is mainly composed of an alloy containing at least one metal element selected from the group consisting of Co, Ni, and Fe,
The metal bonding layer is mainly composed of at least one alloy represented by the general formula MCrAlY (wherein M represents Ni and / or Co, Cr represents chromium, Al represents aluminum, and Y represents yttrium). It is preferable to do.
In this specification, the “main component” is defined as a component of 30% by mass or more.

According to the present invention, it is possible to provide a novel ceramic laminate suitable for a thermal barrier coating structure or the like, which has good thermal barrier properties, thermal shock resistance, and oxygen barrier properties, and has suppressed interfacial peeling between layers. .
The present invention can also provide a novel thermal barrier coating structure that has good thermal barrier properties, thermal shock resistance, and oxygen barrier properties and that suppresses interfacial delamination between layers.

"First embodiment"
With reference to drawings, the ceramic laminated body of 1st embodiment which concerns on this invention, and the thermal-insulation coating structure provided with the same are demonstrated. The thermal barrier coating structure is used for protecting a metal base material from heat in, for example, an aircraft jet engine or a power generation gas turbine.

  FIG. 1 is a cross-sectional view of a metal substrate and a thermal barrier coating structure formed thereon. FIG. 2 is a cross-sectional view corresponding to FIG. 1, the left figure shows the state before the sealing layer 15 is formed, and the right figure shows the state after the sealing layer 15 is formed. In order to facilitate visual recognition, the scale of the constituent elements is appropriately changed from the actual one. In particular, the pores 13p of the ceramic heat shield layer 13 and the surface irregularities of the ceramic heat shield layer 13 are exaggerated and schematically illustrated.

  As shown in FIG. 1, the thermal barrier coating structure 1 has a laminated structure of a metal bonding layer (bond coat) 12, a ceramic thermal barrier layer (top coat) 13, and a sealing layer 15 formed on a metal substrate 11. have. By forming the ceramic heat shield layer 13 having a low thermal conductivity on the combustion gas flow path side, it is possible to extend the life without exposing the metal substrate 11 to a high temperature.

  The composition of the metal substrate 11 is not particularly limited, and in the above application, for example, an alloy containing at least one metal element selected from the group consisting of Co, Ni, and Fe (preferably a so-called “super heat-resistant alloy”). The main component is preferred.

“Super heat resistant alloy” refers to a group of advanced materials that can be used in a high temperature region of 1000 to 2000 ° C. under severe environments such as large stress, oxidation and corrosion. Specifically, as a super heat-resistant alloy, a ternary intermetallic compound of cobalt, aluminum, and tungsten (Co ₃ (Al, W)); an alloy mainly composed of nickel, copper, and iron (Ni: 66. 5% / Cu: 31.5% / Fe: 1.2%) and the like.

  The metal bonding layer 12 is a metal coating layer for the purpose of oxidation resistance of the metal substrate 11. The film thickness of the metal bonding layer 12 is not particularly limited, and is preferably 50 to 100 μm, for example.

The composition of the metal bonding layer 12 is not particularly limited. In the above application, the metal bonding layer 12 preferably contains Al, and more preferably contains Al and Pt.
Since higher corrosion resistance and oxidation resistance can be obtained, in the above application, the metal bonding layer 12 has a general formula MCrAlY (wherein M is Ni and / or Co, Cr is chromium, Al is aluminum, and Y is yttrium. It is more preferable to include an alloy represented by:

The metal bonding layer 12 can be formed by a known method described in Non-Patent Document 1 or the like.
Examples of the method for forming the metal bonding layer 12 containing Al include an Al diffusion coating method. For example, b-NiAl or the like is caused by causing a chemical reaction on the surface of the base material 11 by bringing an aluminum halide such as AlCl ₃ into contact with the surface of the metal base material 11 (Ni-based super heat-resistant alloy or the like) containing Ni. The metal bonding layer 12 containing can be formed. This process is called an aluminizing process.

  Prior to the aluminizing step, a Pt film having a thickness of, for example, about 5 to 10 μm is formed on the surface of the metal substrate 11, and Pt is diffused in the surface layer of the metal substrate 11, so that Al and Pt are dispersed. A metal bonding layer 12 can be formed. It is known that the oxidation resistance and life of the aluminized layer are improved by including Pt in the metal bonding layer 12. This coating method is called a Pt—Al coating method and is the most common method as a bond coat for an aircraft turbine blade.

  The metal bonding layer 12 including the alloy represented by the above general formula MCrAlY is formed by a low-pressure plasma spray (LPPS (VPS)) method or a high velocity gas flame spray (High Velocity Oxy-Fuel: HVOF). ) Method or the like. These methods are said to be higher in production cost than the Al diffusion coating method capable of performing a large amount of coating treatment at a time, but have an advantage that the degree of freedom in designing the coating composition is great.

  The thermal barrier coating structure 1 includes a ceramic laminate 2 of a ceramic thermal barrier layer (first ceramic film) 13 and a sealing layer (second ceramic film) 15. In the present embodiment, these two ceramic films are formed by different film forming methods and have different film structures.

The composition of the ceramic thermal barrier layer 13 is not particularly limited, and in the above application, for example, the ceramic thermal barrier layer 13 includes at least one oxide ceramic selected from the group consisting of Al ₂ O ₃ , HfO ₂ , CeO ₂ , and ZrO _2. Those containing such a component as a main component are particularly preferable.
If the ceramic thermal barrier layer 13 comprises ZrO _2, the _{ZrO 2, Y 2 O 3,} CaO, and at least one stabilizing agent is partially stabilized been added is selected from the group of MgO, etc. More preferably, ZrO ₂ is included in the form of partially stabilized zirconia.
The film thickness of the ceramic heat shield layer 13 is not particularly limited, and is preferably 10 to 300 μm, for example.

  In the present embodiment, the ceramic heat shield layer 13 is a film formed by a plasma spraying method. The ceramic heat-insulating layer 13 is a porous film having a large number of pores 13p therein (see the cross-sectional photograph of FIG. 7 given in the section of “Background Art”), and these pores 13p provide thermal insulation and thermal shock resistance. To express. Since the thermal insulation and thermal shock resistance are good, the relative density of the ceramic thermal insulation layer 13 is set to 50 to 95%.

  The pore diameter of the ceramic thermal barrier layer 13 can be measured by SEM cross-sectional observation. The pore diameter of the ceramic heat shield layer 13 is not particularly limited, and is preferably about 3 to 100 μm, for example.

  As described in the section “Problems to be Solved by the Invention”, in the sprayed coating, many pores 13p are often communicated with each other, and the metal bonding layer that is substantially the base from the surface of the thermal barrier layer 13 is used. In many cases, a through-hole penetrating the heat shield layer 13 up to the surface of 12 is formed. In FIG. 1, at first glance, it seems that many pores 13p formed in the sprayed coating are independent from each other, but in reality, a large number of fine pores 13p are also formed in a portion that looks dense.

  When a special treatment is not performed on the ceramic heat shield layer 13, in a structure in which a through hole that substantially penetrates the heat shield layer 13 is formed, the metal bonding layer 12 comes into contact with the outside air through the through hole. Therefore, the heat shielding effect is reduced accordingly. Further, since oxygen gas in the outside air reaches the surface of the metal bonding layer 12 through the through hole, a metal oxide (TGO) is generated on the surface of the metal bonding layer 12, and this TGO grows, thereby blocking the barrier. There is also a possibility that interface peeling occurs between the thermal layer 13 and the metal bonding layer 12. In order to solve such a problem, in this embodiment, a sealing layer 15 that seals the through hole that substantially penetrates the thermal barrier layer 13 is provided on the ceramic thermal barrier layer 13.

The composition of the sealing layer 15 is not particularly limited, and in the above application, for example, a material containing at least one oxide ceramic selected from the group of Al ₂ O ₃ , HfO ₂ , CeO ₂ , and ZrO ₂ is preferable. Particularly preferred are those containing such a component as a main component.
If Fuanaso 15 comprises ZrO _2, the _{ZrO 2, Y 2 O 3,} CaO, and at least one added stabilizing agent partially stabilized moiety selected from the group such as MgO More preferably, ZrO ₂ is included in the form of stabilized zirconia.

  The sealing layer 15 is a dense film provided for the purpose of sealing the through hole substantially penetrating the heat shield layer 13. Specifically, the sealing layer 15 is a film having a relative density of 95% or higher and a relative density higher than that of the ceramic heat shield layer 13.

  The film thickness of the sealing layer 15 is not particularly limited, and functions sufficiently as the sealing layer 15 if the surface of the ceramic heat shield layer 13 can be sufficiently covered. The thicker the sealing layer 15, the longer the film formation time and film formation cost. Therefore, the thickness of the sealing layer 15 is preferably 1 to 10 μm, for example.

  In the present embodiment, the sealing layer 15 is a film formed by an aerosol deposition (AD) method. The AD method is a method in which an aerosolized ceramic raw material powder is collided on a film forming substrate to crush primary particles in the raw material powder, and a crushed material powder is deposited on the film forming substrate to form a film. It is. “Aerosol” refers to solid or liquid particles suspended in a gas. The AD method is known as a method capable of forming a film of ceramics or the like at a relatively low temperature without requiring a sintering process. The AD method is also called a jet deposition method or a gas deposition method.

  Hereinafter, a method for forming the sealing layer 15 will be described in detail. In forming the sealing layer 15, the metal substrate 11 on which the metal bonding layer 12 and the ceramic heat shield layer 13 are formed is the film forming substrate.

  First, ceramic raw material powder is prepared. In the AD method, primary particles in the raw material powder are crushed by the collision energy of the raw material powder against the film-forming substrate. If the other AD conditions such as the aerosol injection speed are the same, the larger the primary particle diameter of the raw material powder, the larger the kinetic energy, so the collision energy against the film-forming substrate tends to increase. The average primary particle diameter of the raw material powder is not particularly limited, and is preferably 0.1 to 1.0 μm, for example.

  Next, the raw material powder is aerosolized and collided with the film forming substrate to crush primary particles in the raw material powder, and the crushed material powder is deposited on the film forming substrate to form a film. Perform (deposition step). In the AD method, the aerosol containing the raw material powder collides with the film forming substrate with a large kinetic energy. At this time, many primary particles are crushed to become crushed material having a finer particle diameter and deposited on the film forming substrate. In the AD method, a very dense film can be formed by depositing these fine crushed materials. The ceramic thermal barrier layer 13 formed by the plasma spraying method is not so good in surface smoothness, but the AD method can form a dense film with good adhesion irrespective of the surface smoothness level of the base. . Specifically, a dense film having a relative density of 95% or more and a relative density higher than the relative density of the ceramic heat shield layer 13 can be formed with good adhesion.

  It is not essential to perform the heat treatment after the deposition step, but the heat treatment step may be performed after the deposition step. Perform heat treatment on the film formed after the deposition step, preferably heat treatment at a temperature higher than the sintering temperature (for example, heat treatment at 1500 ° C. or higher in the case of an alumina film or a YSZ (yttria stabilized zirconia) film)). Then, the crushed material grows and crystal grains having a larger particle diameter are generated, and a denser film is obtained.

  The thermal barrier coating structure 1 of this embodiment includes a ceramic thermal barrier layer 13 having a relative density of 50 to 95% formed by a plasma spraying method and a dense hole having a relative density of 95% or more formed by an AD method. The ceramic laminate 2 with the layer 15 is provided. In the present embodiment, since the dense sealing layer 15 is formed on the ceramic heat shielding layer 13, it is possible to prevent outside air from entering into the pores 13 p of the ceramic heat shielding layer 13, and there is no sealing layer 15. Higher heat shielding properties are exhibited.

  In the present embodiment, the presence of the sealing layer 15 suppresses oxygen gas in the outside air from reaching the surface of the metal bonding layer 12 through the pores 13p of the ceramic heat shield layer 13, so that the oxygen barrier property is also improved. It is good. Therefore, in the present embodiment, generation of metal oxide (TGO) on the surface of the metal bonding layer 12 and interface peeling between the ceramic heat shield layer 13 and the metal bonding layer 12 due to this are suppressed.

  In this embodiment, unlike Patent Document 1, it is not necessary to provide an oxygen barrier layer between the metal bonding layer and the ceramic heat shield layer. Generally, an oxygen barrier layer formed by a wet method such as a sol-gel method or a slurry method, or a normal vapor phase film formation method does not have good adhesion to the base and cannot withstand repeated thermal shocks. There is a risk of interfacial delamination. In this embodiment, since it is not necessary to provide an oxygen barrier layer between the metal bonding layer and the ceramic heat shield layer, there is no problem with the oxygen barrier layer.

  As described in the section “Problems to be Solved by the Invention”, in the sealing treatment for the conventional sprayed coating using the sealing coating, the sealing coating hardly remains on the surface of the sprayed coating, It enters the inside of the sprayed film and fills the pores (see FIG. 9).

  On the other hand, in the film formation by the AD method, due to factors such as turbulent flow of the carrier gas, the raw material powder or its crushed material hardly enters the inside of the ceramic heat shield layer 13 and on the surface of the ceramic heat shield layer 13. accumulate. Specifically, the amount of the raw material powder or its crushed material entering the inside of the ceramic heat shield layer 13 is such that it enters into the recesses of the surface irregularities of the sprayed film or bites into the surface layer due to the anchoring effect.

  Therefore, in the present embodiment, a structure in which the sealing layer 15 exists on the surface of the ceramic heat shield layer 13 is obtained without almost entering the ceramic heat shield layer 13. In such a structure, the pores 13p of the ceramic heat shield layer 13 are not blocked, and the porous structure is maintained. Therefore, the formation of the sealing layer 15 impairs the thermal insulation and thermal shock resistance of the ceramic heat shield layer 13. There is no end to it.

  As described above, in the present embodiment, the sealing layer 15 hardly enters the ceramic heat shield layer 13 and a structure existing on the surface of the ceramic heat shield layer 13 is obtained. However, the heat shield property and the thermal shock resistance are obtained. If there is no problem for use of the thermal barrier coating structure 1, a part of the sealing layer 15 may enter the ceramic thermal barrier layer 13.

  As described above, according to this embodiment, it is possible to provide a thermal barrier coating structure 1 that has good thermal barrier properties, thermal shock resistance, and oxygen barrier properties and that suppresses interfacial delamination between layers.

  In the thermal barrier coating structure 1 of this embodiment, the laminated structure of the ceramic thermal barrier layer 13 and the sealing layer 15 provides good thermal barrier properties / thermal shock resistance / oxygen barrier properties. There is no need to provide a layer other than the thermal layer 13 / sealing layer 15. However, other layers may be provided as necessary.

  A second ceramic film having a relative density of 95% or more and a relative density higher than that of the first ceramic film was laminated on the first ceramic film having a relative density of 95% or less. The structure ceramic laminate itself is novel. According to the present invention, it is possible to provide a novel ceramic laminate suitable for a thermal barrier coating structure or the like, which has good thermal barrier properties, thermal shock resistance, and oxygen barrier properties, and has suppressed interfacial peeling between layers. .

"Second embodiment"
With reference to drawings, the ceramic laminated body of 2nd embodiment which concerns on this invention, and the thermal-insulation coating structure provided with the same are demonstrated.
3 and 4 are cross-sectional views corresponding to FIGS. 1 and 2 of the first embodiment. In order to facilitate visual recognition, the scale of the constituent elements is appropriately changed from the actual one. In particular, the columnar crystals 14c and the through holes 14p forming the ceramic heat shield layer 14 and the surface irregularities of the ceramic heat shield layer 14 are exaggerated and schematically illustrated. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 3, the thermal barrier coating structure 3 of the present embodiment includes a metal bonding layer (bond coat) 12, a ceramic thermal barrier layer (top coat) 14, and a sealing layer 15 formed on a metal substrate 11. And a laminated structure.

  The thermal barrier coating structure 3 includes a ceramic thermal barrier layer (first ceramic film) 14 formed by an EB-PVD (electron beam evaporation) method and a sealing layer (second ceramic film) formed by an AD method. ) 15 and the laminate 4. The basic configuration of the thermal barrier coating structure 3 is the same as that of the first embodiment. Instead of the ceramic thermal barrier layer 13 formed by plasma spraying, a ceramic thermal barrier layer 14 formed by EB-PVD method is used. It is provided.

The composition of the ceramic thermal barrier layer 14 is not particularly limited, and includes at least one oxide ceramic selected from the group of, for example, Al ₂ O ₃ , HfO ₂ , CeO ₂ , and ZrO ₂ as in the first embodiment. Those containing such components as the main component are particularly preferred.
If the ceramic thermal barrier layer 14 comprises ZrO _2, the _{ZrO 2, Y 2 O 3,} CaO, and at least one stabilizing agent is partially stabilized been added is selected from the group of MgO, etc. More preferably, ZrO ₂ is included in the form of partially stabilized zirconia.
The film thickness of the ceramic heat shield layer 14 is not particularly limited, and is preferably 10 to 300 μm, for example.

The ceramic heat shield layer 14 formed by the EB-PVD method has a columnar structure composed of a large number of columnar crystals 14c extending in a non-parallel direction, for example, a substantially vertical direction with respect to the substrate surface. In such a structure, a through-hole 14p that penetrates the heat shield layer 14 is formed between the columnar crystals 14c adjacent to each other from the surface of the heat shield layer 14 to the surface of the metal bonding layer 12 that is the base. That is, the ceramic heat shield layer 14 is a porous film having a large number of through-holes 14p therein (see the cross-sectional photograph of FIG. 8 given in the section of “Background Art”). Thermal shock resistance is manifested. Since the thermal insulation and thermal shock resistance are good, the relative density of the ceramic thermal insulation layer 14 is 50 to 95%.
The diameter of the through hole of the ceramic heat shield layer 14 can be measured by SEM cross-sectional observation. The through-hole diameter of the ceramic heat shield layer 14 is not particularly limited and is preferably about 10 nm to 10 μm, for example.

In the present embodiment, a sealing layer 15 is provided on the ceramic heat shield layer 14 to seal the through hole 14p that penetrates the heat shield layer 14. The film forming method and film structure of the sealing layer 15 are the same as those in the first embodiment.
Similarly to the first embodiment, a dense sealing layer 15 having a relative density of 95% or more can be formed with good adhesion on the ceramic heat shield layer 14 formed by the EB-PVD method by the AD method. .

  As in the first embodiment, the raw material powder or the crushed material thereof may enter the depressions on the surface unevenness of the EB-PVD film or may bite into the surface layer due to the anchoring effect. Depending on the relationship between the diameter of the through-hole formed between the columnar crystals adjacent to each other in the EB-PVD film and the diameter of the raw material powder or its crushed material, the raw material powder or its crushed material may penetrate the EB-PVD film. It may get into the hole somewhat.

  However, in film formation by the AD method, the raw material powder or the crushed material thereof does not actively enter the ceramic heat shield layer 14 due to factors such as turbulent flow of the carrier gas. Accordingly, also in the present embodiment, the ceramic laminate 4 having a structure in which the sealing layer 15 exists on the surface of the ceramic heat shield layer 14 is obtained without almost entering the ceramic heat shield layer 14. In such a structure, the through hole 14p of the ceramic heat shield layer 14 is not closed, and the porous structure is maintained. Therefore, the formation of the sealing layer 15 impairs the heat shield property and thermal shock resistance of the ceramic heat shield layer 14. It won't get lost.

  As described above, in this embodiment, a structure in which the sealing layer 15 is present on the surface of the ceramic heat shield layer 14 is obtained without almost entering the inside of the ceramic heat shield layer 14, but the heat shield property and the thermal shock resistance are obtained. If there is no problem for the use of the thermal barrier coating structure 3, a part of the sealing layer 15 may enter the ceramic thermal barrier layer 14.

  Also in the present embodiment, similar to the first embodiment, the ceramic laminate 4 and the thermal barrier coating structure 3 that have good thermal barrier properties, thermal shock resistance, and oxygen barrier properties and that suppress interfacial delamination between layers are provided. be able to.

"Deposition system"
With reference to FIG. 5, a configuration example of an AD film forming apparatus suitable for use in forming the sealing layer 15 will be described. An AD film forming apparatus 5 shown in FIG. 5 includes an aerosol generating unit 20 that generates aerosol, a film forming unit 40, an aerosol transport pipe 30 that connects the two, and a control unit 50 that controls the operation of each unit. And.

  The aerosol generation unit 20 includes an aerosol generation container 21, a vibration table 22, a hoisting gas nozzle 23, and a pressure adjusting gas nozzle 24. The raw material powder 61 is charged into the aerosol generation container 21, and generation of the aerosol is performed here. The aerosol generation container 21 is installed on a vibration table 22 that vibrates at a predetermined frequency in order to stir the raw material powder 61 and efficiently generate an aerosol.

  The hoisting gas nozzle 23 generates a cyclone flow by introducing a carrier gas supplied from an external gas cylinder into the aerosol generating container 21. Thereby, the raw material powder 61 in the aerosol generation container 21 is rolled up and dispersed, and an aerosol is generated. The pressure adjusting gas nozzle 24 adjusts the gas pressure in the aerosol generating container 21 by introducing a carrier gas supplied from an external gas cylinder into the aerosol generating container 21. Thereby, the difference between the pressure in the aerosol generation container 21 and the pressure in the film forming chamber 41 is adjusted.

The flow rate of the gas introduced by the hoisting gas nozzle 23 and the pressure adjusting gas nozzle 24 is adjusted by the flow rate adjusting units 23a and 24a. As the carrier gas supplied by the gas nozzles 23 and 24, He, O ₂ , N ₂ , Ar, a mixed gas thereof, dry air, or the like is used.

  The aerosol generated by the aerosol generating unit 20 is transported to the film forming unit 40 via the aerosol transport pipe 30. In the film forming chamber 41, the aerosol transport pipe 30 is connected to an injection nozzle 42 for injecting the aerosol.

  The film forming unit 40 includes a film forming chamber 41, an injection nozzle 42, a stage 48, and an exhaust pipe 49. The inside of the film forming chamber 41 can be evacuated by an exhaust pump connected to an exhaust pipe 49. During film formation, the inside of the film formation chamber 41 is maintained at a predetermined reduced pressure, preferably 100 Pa or less. The injection nozzle 42 has an opening having a predetermined shape and size, and injects the aerosol of the raw material powder supplied from the aerosol generation container 21 via the aerosol transport pipe 30 toward the film forming substrate 60. . The velocity of the aerosol ejected from the ejection nozzle 42 is determined by the pressure difference between the aerosol generation container 21 and the film forming chamber 41.

  The stage 48 to which the film forming substrate 60 is fixed is a stage that can be moved three-dimensionally to control the relative position and relative speed between the film forming substrate 60 and the injection nozzle 42. By adjusting this relative speed, the thickness of the film formed per reciprocation is controlled. In the present embodiment, the relative position between the injection nozzle 42 and the film forming substrate 60 is changed by moving the stage 48 side. However, the position of the film forming substrate 60 is fixed and the injection nozzle 42 side is fixed. May be moved.

  During film formation, the raw material powder 61 is disposed in the aerosol generation container 21 and the film formation substrate 60 is disposed on the stage 48. When the film forming apparatus 5 is driven, the aerosol generated in the aerosol generating container 21 is introduced into the film forming chamber 41 through the aerosol transport pipe 30, sprayed from the spray nozzle 42, and sprayed onto the film forming substrate 60. The raw material powder 61 in the aerosol collides with the film forming substrate 60 and is crushed, and the crushed material is deposited on the film forming substrate 60. At this time, the stage 48 is moved at a predetermined speed under the control of the control unit 50, so that the stage 48 is moved at a rate corresponding to the moving speed of the stage 48 (relative speed between the spray nozzle 42 and the film forming substrate 60). A ceramic film 62 having the same composition as the raw material powder 61 is formed.

  Instead of the aerosol generation unit 20, an aerosol generation device 6 shown in FIG. 6 may be used. FIG. 6A is a cross-sectional view showing the configuration of the aerosol generating device, and FIG. 6B is a plan view showing the inside of the aerosol generating device.

  The aerosol generation device 6 shown in FIGS. 6A and 6B includes a powder storage chamber 70 and an aerosol generation unit 80. The powder storage chamber 70 is a chamber for storing powder, and a powder supply port 70a is provided at the upper bottom thereof, and an opening 71 is formed at the lower bottom thereof. The powder storage chamber 70 and the aerosol generation unit 80 are connected via the opening 71.

  The powder storage chamber 70 is provided with a stirring blade 72 that rotates when driven by a motor. An O-ring 73 a is fitted on the rotating shaft 73 of the stirring blade 72, thereby ensuring airtightness in the powder storage chamber 70. The powder is stored in such a powder storage chamber 70, and the powder is stirred by the stirring blade 72. Thereby, the powder falls from the opening 71 and is led out to the aerosol generating unit 80. In addition, an assist gas introduction unit 74 is provided in the powder storage chamber 70 in order to assist or promote the powder being led out from the opening 71. The assist gas introduction unit 74 includes a pipe and a valve, and a gas cylinder, for example, is connected to the tip of the pipe.

  The aerosol generating unit 80 includes a rotating disk 81 that rotates when driven by a motor. An O-ring 82 a is fitted on the rotation shaft 82 of the turntable 81, thereby ensuring airtightness in the aerosol generating unit 80. A groove 83 having a predetermined width and depth is formed in the turntable 81 along the circumference. The turntable 81 is arranged so that the groove 83 faces the opening 71 of the powder storage chamber 70. Such a rotating plate 81 conveys the powder at a certain ratio by rotating while receiving the powder dropped from the opening 71 through the groove 83.

Further, the aerosol generation unit 80 is provided with a dispersed gas introduction unit 84 and an aerosol supply pipe 85. The dispersed gas introduction part 84 includes a pipe and a valve, and a gas cylinder, for example, is connected to the end of the pipe. As the assist gas and the dispersion gas, N ₂ , O ₂ , He, Ar, a mixed gas thereof, dry air, or the like is used.

  As shown in FIG. 6A, the outlet of the dispersed gas introduced into the aerosol generating unit 80 by the dispersed gas introducing unit 84 is provided so as to face the groove 83 of the turntable 81. The aerosol supply pipe 85 is a pipe disposed so that the opening at the front end faces the groove 83, and the other end is connected to the aerosol carrying pipe 30 shown in FIG. 5 via a pipe formed of, for example, a flexible material. Connected to.

  In such an aerosol generating device 6, desired powder is stored in the powder storage chamber 70 and the stirring blade 72 is driven, and the rotating plate 81 is rotated in the aerosol generating unit 80, and the groove 83 of the rotating plate 81 is formed. A dispersion gas is sprayed on the surface. The powder stored in the powder storage chamber 70 falls into the groove 83 through the opening 71 while being stirred by the stirring blade 72. At that time, an air flow is formed in the opening 71 by introducing an assist gas into the powder storage chamber 70. This airflow acts as a driving force that assists or accelerates the derivation of the powder. Thereby, the powder falls from the opening 71 into the groove 83 more smoothly. The powder that has fallen into the groove 83 is deposited and conveyed in accordance with the rotational speed of the turntable 82. The introduction of the assist gas may be continuous or intermittent.

  On the other hand, in the groove 83 of the turntable 82, the dispersed gas blown there flows along the groove 83 to form an air flow. This dispersed gas flows into the aerosol supply pipe 85 from the opening at the tip thereof. At that time, a suction force toward the inside of the aerosol supply pipe 85 is generated around the aerosol supply pipe 85. Due to this suction force, the powder accumulated in the groove 83 flows into the aerosol supply pipe 85 together with the dispersion gas. The aerosol thus generated is supplied from the aerosol supply pipe 85 to the aerosol transport pipe 30 (FIG. 5), and is introduced into the film forming unit 40 through the aerosol transport pipe 30.

  The ceramic laminate of the present invention can be preferably used for a thermal barrier coating structure for protecting a member used in a high temperature environment from heat.

Sectional drawing which shows typically the thermal barrier coating structure of 1st embodiment which concerns on this invention It is sectional drawing corresponding to FIG. 1, and is a figure which shows the state before film-forming of a sealing layer and after film-forming Sectional drawing which shows typically the thermal barrier coating structure of 2nd embodiment which concerns on this invention FIG. 4 is a cross-sectional view corresponding to FIG. 3, illustrating a state before and after the sealing layer is formed. The figure which shows the structural example of AD film-forming apparatus Diagram showing an example of design change of the deposition system Diagram showing an example of design change of the deposition system Thermal barrier coating structure described in Patent Document 1 Thermal barrier coating structure described in Non-Patent Document 1 Explanatory drawing explaining the conventional sealing process with respect to a sprayed film

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3 Thermal-insulation coating structure 2, 4 Ceramic laminated body 11 Metal base material 12 Metal joining layer 13, 14 Ceramic thermal-insulation layer (1st ceramic film)
15 Sealing layer (second ceramic film)

Claims (7)

On the first ceramic film having a relative density of 95% or less,
A ceramic laminate, wherein a second ceramic film having a relative density of 95% or more and a relative density higher than that of the first ceramic film is laminated.   2. The ceramic laminate according to claim 1, wherein at least a part of the second ceramic film is present on a surface of the first ceramic film.   The ceramic laminate according to claim 1 or 2, wherein the second ceramic film is formed by an aerosol deposition method.   The ceramic laminate according to any one of claims 1 to 3, wherein the first ceramic film is formed by a plasma spraying method or an electron beam evaporation method. The first ceramic film includes at least one oxide ceramic selected from the group consisting of Al ₂ O ₃ , HfO ₂ , CeO ₂ , and ZrO ₂ ;
Said second ceramic _{film, Al 2 O 3, HfO 2} , CeO 2, and any one of the preceding claims, characterized in that it comprises at least one oxide ceramic which is selected from the group of ZrO ₂ The ceramic laminate according to 1. In a thermal barrier coating structure for protecting a metal substrate from heat,
The metal base layer side has a structure in which a metal bonding layer, a ceramic heat shield layer, and a sealing layer are sequentially laminated,
A thermal barrier coating structure, wherein the laminate of the ceramic thermal barrier layer and the sealing layer comprises the ceramic laminate according to any one of claims 1 to 5. The metal base material is mainly composed of an alloy containing at least one metal element selected from the group consisting of Co, Ni, and Fe,
The metal bonding layer is mainly composed of at least one alloy represented by the general formula MCrAlY (wherein M represents Ni and / or Co, Cr represents chromium, Al represents aluminum, and Y represents yttrium). The thermal barrier coating structure according to claim 6.