JP3410955B2 - Heat resistant member and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat-resistant member having a ceramic coating layer and a method for manufacturing the same.

[0002]

2. Description of the Related Art Along with the increase in the operating temperature of equipment aimed at improving the efficiency of high-temperature equipment represented by gas turbines for power generation and engines, the materials used in the equipment components have become higher in level. Properties such as high temperature strength, high temperature corrosion resistance and oxidation resistance are required. Therefore, M-Cr-Al-Y (M = N) is formed on the surface of the high-strength Ni-based or Co-based superalloy.
A technique for applying a corrosion-resistant / oxidation-resistant metal coating made of an alloy (i, Co, etc.) has been developed and has already been widely applied as an indispensable technique for the dynamic / static vanes of a gas turbine.

In addition, in the flow of higher temperature, corrosion-resistant and oxidation-resistant metal coating alone is already inadequate as a material property. Therefore, the surface of the metal coating layer is coated with a ceramic coating having a low thermal conductivity. ,
Thermal barrier coating technology for cooling the inside is also being put to practical use. As the constituent material of the ceramic layer, high temperature strength,
Due to characteristics such as thermal conductivity and thermal expansion coefficient, Y ₂ O ₃ stabilized Z
rO ₂ is the most widely applied.

However, when a member having a thermal barrier coating on the surface of a metal member is used in a high temperature atmosphere, thermal stress occurs due to the difference in thermal expansion coefficient between the metallic member and the thermal barrier coating layer (ceramic layer), There is a problem that the ceramic layer is easily peeled off. In particular, cracks develop near the interface between the metal member and the ceramics layer, and the ceramics layer peels off. When the ceramic layer peels off,
Since it cannot be used continuously for a long time in a high temperature atmosphere, a ceramic coating layer that is resistant to peeling is desired from the viewpoint of extending the life of the thermal barrier coating member.

On the other hand, as a means for suppressing crack growth in a general ceramic member, particles, whiskers, fibers and the like are dispersed in a ceramic material to form a complex internal structure and increase fracture strength and fracture toughness. The method is known. For example, as an example of increasing the fracture toughness value, which is a measure for suppressing the progress of cracks, a green compact obtained by dispersing SiC fibers or carbon fibers in a non-oxide ceramic material such as SiC or Si ₃ N ₄ is fired. The joined parts (sintered body),
Β-Si having acicular structure in Si ₃ N ₄ matrix
It has been reported that a member and the like in which ₃ N ₄ is deposited in the firing process.

Further, even in a member using Ce-stabilized zirconia as a matrix, La-β-
By precipitating tabular grains made of alumina,
It has been reported that the effect of improving fracture toughness (effect of suppressing crack growth) was obtained (Fujii, Hirano et al., Proceedings of Annual Meeting of The Ceramic Society of Japan, 2C-02, 1993, etc.).

Regarding ceramic layers used for thermal barrier coatings of power plants, aircraft gas turbine blades, combustors, etc., it has been considered to compound the internal structure of the layers in order to improve the peeling life. It was As one of them, similar to the above-mentioned sintered body, an attempt was made to disperse particles (spherical, lumpy, flat plate, fibrous particles, etc.) inside the thermal barrier coating layer for the purpose of improving the peeling life of the layer. (Eg Surf. And Coat. Tech., CCB
erndt and JHYI, 37 (1989) p89-110).

However, the thermal barrier coating is mainly produced by a unique method different from the firing process called the thermal spraying method, that is, a method of forming a coating layer by colliding and solidifying molten particles at a high speed. In the method of previously mixing the reinforcing fibers and the reinforcing particles as described above, the reinforcing substance is also melted in the thermal spraying process, and it is not possible to obtain a dispersion-strengthened ceramic layer.

That is, in the thermal spraying method, flat particles produced by collision and solidification of molten particles are laminated to form a coating layer having a film thickness of about 200 to 500 μm. Therefore, for the purpose of dispersing the fibrous, needle-shaped, and plate-shaped particles, even if thermal spraying is performed using a powder in which these particles are mixed with matrix-constituting particles, they are melted in the plasma flame. It is not possible to disperse particles having a desired shape, such as spherical particles, in the ceramic coating layer. For this reason, many attempts have been made to directly disperse fibrous particles (for example, alumina fibers) having a shape other than flat particles (spray-solidified particles) using the thermal spraying method, but until now, they have succeeded. Not not.

Further, even if the dispersed phase is generated by an indirect means (heat treatment) so as to disperse the tabular grains of La-β-alumina in the zirconia sintered body, in this system, the member is heated at a high temperature. It is necessary to heat-treat (1600 ℃ or higher). In a heat-resistant member composed of a composite member with a metal member, such heat treatment has an adverse effect on the metal member and cannot be practically performed. Due to such restrictions, there is no example in which the internal structure is compounded by heat-treating the ceramic layer as the heat shield layer.

[0011]

As described above, in the conventional heat-resistant member in which the ceramic layer is formed on the metal member by coating, the ceramic layer is easily peeled off due to the difference in thermal expansion between the metal member and the ceramic layer. However, there is a problem in that the protective property of the metal layer cannot be sufficiently maintained for a long time. In addition, it is very difficult to produce a thermal barrier coating containing dispersed particles for the purpose of improving the peeling life with the current coating process (spraying method etc.) and material composition.

The present invention has been made in order to solve such a problem, and provides a heat-resistant member that suppresses peeling of a ceramic layer for a long time in a high temperature atmosphere and achieves a long life, and a method for manufacturing the same. Is intended.

[0013]

The heat resistant member of the present invention comprises, as described in claim 1, a metal base material made of an alloy containing at least one element selected from Ni, Co and Fe as a main component. , M-C coated on the metal substrate
r-Al-Y alloy layer (where M is Ni, Co and F
In a heat-resistant member comprising a ceramic layer provided on the M-Cr-Al-Y alloy layer, the ceramic layer is mainly a matrix. It is characterized by having a material and dispersed particles arranged in the matrix material and agglomerated particles of composite oxide particles containing an alkaline earth element.

In the heat-resistant member of the present invention, the aggregated particles include, for example, as described in claim 2, an alkaline earth element and at least one metal element mainly selected from W, Ti, Ta, Mo and Nb. It is preferable that the particles are composed of a composite oxide containing a compound and at least one of tabular grains and acicular particles of the complex oxide is aggregated.

The method for producing a heat-resistant member according to the present invention is defined in claim 3.
As described in 1., a metal base material made of an alloy containing at least one element selected from Ni, Co and Fe as a main component, and M-Cr-A coated on the metal base material.
1-Y alloy layer (where M represents at least one element selected from Ni, Co and Fe) and the above-mentioned MC
In manufacturing a heat-resistant member comprising a ceramic layer formed by coating on an r-Al-Y alloy layer, a matrix material mainly constituting the ceramic layer, an alkaline earth element, W, Ti, Ta, Mo And a step of forming the ceramics layer on the M-Cr-Al-Y alloy layer by using a raw material powder containing at least one metal element selected from Nb and Nb, and 500 to 1400 A heat treatment at a temperature in the range of ° C., agglomerated particles obtained by aggregating the composite oxide particles containing the alkaline earth element and the metal element, dispersed and precipitated in the ceramic layer, It has a feature.

In the heat resistant member of the present invention, a composite oxide containing an alkaline earth element in the ceramic layer, for example, an alkaline earth element and at least one metal element selected from W, Ti, Ta, Mo and Nb. Aggregated particles obtained by aggregating particles of a composite oxide containing and are dispersed and arranged. Since these agglomerated particles have the effect of suppressing the crack growth rate that affects the peeling life of the ceramic layer,
It is possible to stably suppress the peeling of the ceramic layer due to the thermal stress generated when the ceramic layer is used in a high temperature atmosphere. In particular, the composite oxide particles also have a crack growth suppressing effect individually, and since such composite oxide particles are used as agglomerated particles, a larger crack growth suppressing effect can be obtained. .

Here, a compound (for example, an oxide) containing an alkaline earth element such as Mg or Ca, and mainly W or T
When heat-treated in a state of being mixed with a compound (eg, an oxide) containing at least one metal element selected from i, Ta, Mo and Nb, the temperature is relatively low (eg, 500 to 1400).
(Eg, MgWO ₄ , MgTiO ₃ , M
Complex oxides such as gTa ₂ O ₆ , MgMoO ₄ , and MgNb ₂ O ₆ and similar complex oxides containing Ca are produced. By appropriately selecting the heat treatment conditions at this time and controlling the particle size of the raw material powder of the complex oxide, for example, tabular grains and needle-like grains made of the complex oxide as described above are precipitated and at the same time Aggregated particles obtained by aggregating to an appropriate size are obtained.

As described above, the aggregated particles of the composite oxide as the dispersed particles can be precipitated by applying a heat treatment after forming the ceramics layer. Therefore, like the thermal spraying method, the initial particle shape (acicular particles) is obtained. Particles having a crack growth suppressing effect can be dispersed with good reproducibility even in the inside of a ceramic layer to which a coating method in which (or plate-like particles) are lost is applied. Further, since the aggregated particles of the composite oxide react and deposit at a relatively low temperature such as 500 to 1400 ° C., even in a heat-resistant member composed of a composite member of a metal base material and a ceramics layer, the metal base material is On the other hand, a heat treatment for precipitation of dispersed particles can be performed without adversely affecting.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Modes for carrying out the present invention will be described below.

FIG. 1 is a sectional view schematically showing the structure of the main part of a heat resistant member according to one embodiment of the present invention. In the figure, 1 is a metal base material, and the metal base material 1 is N
Examples thereof include alloys containing at least one element selected from i, Co and Fe as a main component, and various known heat-resistant alloys can be appropriately selected and used according to the intended use. In practice, IN738, IN738LC, IN939, Mar-M247,
It is effective to use Ni-based superalloys such as RENE80, CM-247, CMSX-2 and CMSX-4 and Co-based superalloys such as FSX-414 and Mar-M509.

On the surface of the metal substrate 1 described above, an M-Cr-Al-Y alloy (M is at least 1 selected from Ni, Co and Fe as a corrosion-resistant and oxidation-resistant metal coating layer.
A layer 2 (which represents the seed element) is formed over the coating. M-Cr
Since the -Al-Y alloy layer 2 has a coefficient of thermal expansion intermediate between that of the metal substrate 1 and the ceramic layer 3 described later, it also has the effect of relaxing the difference in thermal expansion.

The M-Cr-Al-Y alloy layer 2 is generally 0.1-20 wt% Al, 10-35 wt% Cr, 0.1- 5% by weight Y
And the balance is at least selected from Ni and Co.
An alloy having a composition consisting essentially of one element is preferably used. Al and Cr need only contain at least one of them, and other active metals such as Hf, Zr, and Ti can be used instead of Y. Depending on the application, Nb, Ta, W, etc. may be contained in a range of about 5% by weight or less. Here, the above-mentioned alloys are generically called M-Cr-Al-Y alloys. Specifically N
iCoCrAlY, CoNiCrAlY, NiCrAl
Y, CoCrAlY, FeCrAlY and the like are preferable.

The M-Cr-Al-Y alloy layer 2 is formed by the thermal spraying method,
It can be formed by various film forming methods such as the PVD method and the CVD method, but the plasma spraying method is most effective in practical use. Particularly, among the plasma spraying methods, a low pressure plasma spraying method in which a spraying process is performed in a reduced pressure atmosphere is preferable, which suppresses the oxidation of the M-Cr-Al-Y alloy layer 2 at the time of film formation and has excellent oxidation resistance. Can be given. The thickness of the M-Cr-Al-Y alloy layer 2 is 10 to 500 μm.
The range can be selected according to the application, for example, about 50 to 300 μm for gas turbine blades, oxidation life and metal base material 1
And is suitable from the viewpoint of the stress relaxation effect of the ceramic layer 3.

On the M-Cr-Al-Y alloy layer 2 as described above, a ceramic layer 3 is formed so as to cover the heat-resistant member 4 used as a constituent material of high-temperature equipment, for example. There is. The ceramic layer 3 is
It can be formed by various spraying methods such as plasma spraying method, high-speed gas flame spraying method (HVOF method), PVD method, CVD method, spin coating method, and the like.
The present invention is particularly effective when the ceramic layer 3 is formed by using the thermal spraying method. Among them, the plasma spraying method is most effective in practice.

The above-mentioned ceramics layer 3 is composed of matrix material 5 which mainly constitutes the ceramics layer 3 and dispersed particles composed of aggregated particles 6 of composite oxide particles which are dispersed in and among the particles of the matrix material 5. have. Here, FIG. 1 shows the ceramics layer 3 formed by the thermal spraying method, and the matrix material 5 is thermal spray solidified particles (melt solidified particles).

Aggregated particles 6 of composite oxide particles are present as dispersed particles in and between the particles of the spray-solidified particles 5. The agglomerated particles 6 as the dispersed particles are mainly composed of, for example, an alkaline earth element such as Mg, Ca, Sr, and Ba and at least one metal element selected from W, Ti, Ta, Mo, and Nb. For example, as shown in FIG. 2, the composite oxide is a particle obtained by aggregating and precipitating reaction product particles (composite oxide particles) 7 of an alkaline earth element and a metal element.

For example, an alkaline earth oxide such as MgO, CaO, SrO or BaO and W, Ti, Ta, Mo and N are contained in the ceramic material constituting the matrix.
When a mixture of an oxide containing at least one metal element selected from b is used as the thermal spraying raw material powder and the ceramic layer 3 is formed by coating by thermal spraying and then heat treatment is performed, The above-mentioned compounds react with each other at a relatively low temperature that does not adversely affect, for example, a temperature of about 500 to 1400 ° C., and composite oxide particles containing an alkaline earth element and the above metal element are generated. Furthermore, by controlling the heat treatment conditions and the particle size of the raw material powder, sintering etc. occurs between the above-mentioned complex oxide particles, and at the same time these particles grow into tabular particles or acicular particles, and these particles agglomerate to form tabular particles. Aggregate particles 6 of needle-shaped composite oxide particles 7 are deposited.

In this way, the agglomerated particles 6 of the flat or needle-shaped composite oxide particles 7 can be deposited within the particles of the spray-coagulated particles 5 or between the particles. The aggregated particles 6 deposited by this heat treatment suppress the growth rate of cracks that propagate inside the ceramic layer 3 made of the matrix material (spray-solidified particles) 5. By such an action, it becomes possible to improve the peeling resistance life of the ceramic layer 3. In this way, the aggregated particles 6 of the composite oxide particles 7 function well as dispersed particles.

In particular, the composite oxide particles 7 constituting the agglomerated particles 6 also have an effect of suppressing crack propagation.
Since such complex oxide particles 7 are used as agglomerated particles, a larger effect of suppressing crack propagation can be obtained. That is, when the crack passes through the agglomerated particles 6, in addition to the effect of suppressing the progress of the crack by the individual composite oxide particles 7, stress relaxation is caused by breaking the agglomerated particles 6. By these, a larger crack growth suppressing effect can be obtained.

The dispersal position of the agglomerated particles 6 is not particularly limited, but if they are dispersed and arranged between the particles of the spray-solidified particles 5, it is effective in suppressing the progress of cracks propagating inside the ceramic layer 3. Target. Furthermore, since the aggregated particles 6 include pores between the composite oxide particles 7, it is possible to obtain the effect of suppressing the progress of cracks without reducing the relaxation property of thermal stress.

Composite oxide particles 7 constituting aggregated particles 6
Is required to mainly contain at least one kind of alkaline earth element selected from Mg, Ca, Sr, Ba and the like and at least one kind of metal element selected from W, Ti, Ta, Mo and Nb, It may further contain elements other than these. The produced complex oxide differs depending on the type of element added at the time of forming the ceramics layer 3 and their composition.

[0032] For example, in the case of using Mg as the alkaline earth _{metals, MgWO 3, MgTiO 3, MgTi} 2
O ₅ , Mg ₂ TiO ₄ , MgTa ₂ O ₆ , Mg ₄ Ta ₂
O ₉ , MgMoO ₄ , Mg ₂ Mo ₃ O ₁₁ , MgNb ₂ O
₆ , Mg ₄ Nb ₂ O _9, etc., when Ca is used as the alkaline earth metal, CaWO ₄ , Ca ₃ WO ₆ , C
aTiO ₃ , Ca ₃ Ti ₂ O ₇ , CaTa ₂ O ₆ , Ca
Ta ₄ O ₁₁ , Ca ₂ Ta ₂ O ₇ , CaMoO ₄ , CaN
etc. _{b 2 O 6, Ca 4 Nb} 2 O 9 and the like. Also,
When Mg and Ca are used together as the alkaline earth metal, for example, a mixture of the above-mentioned composite oxide containing Mg and Ca, a composite oxide containing Mg and Ca at the same time, or a mixture thereof It becomes a mixture.

Particularly, in the heat resistant member 4 which is used for a long time in a high temperature atmosphere (eg, 850 ° C. or higher), MgWO ₃ , M
gMoO ₄ , Mg ₂ TiO ₄ , MgTiO ₃ , MgTi
₂ O ₅ , MgTa ₂ O ₆ , Mg ₄ Ta ₂ O ₉ , MgNb
Aggregated particles 6 made of ₂ O ₆ , Mg ₄ Nb ₂ O ₉ or the like, a similar Ca-containing complex oxide, or a mixture thereof are preferably applied. Since such complex oxide particles 7 have a small change (deformation, decomposition, etc.) during high temperature use, the effect of suppressing the progress of cracks by the agglomerated particles 6 and the effect of suppressing the peeling of the ceramic layer 3 based on the effect are more stable. It becomes possible to obtain.

Among the above-mentioned composite oxides, the composite oxide particles containing Ca in particular tend to generate a reaction phase at the interface with the matrix material 5 constituting the ceramics layer 3, for example, stabilized zirconia, so that cracks propagate. At this time, peeling at the interface between the matrix material 5 and the aggregated particles 6 can be effectively suppressed. This makes it possible to enhance the effect of suppressing the progress of cracks. Further, when Ti or Nb is used as one metal element of the complex oxide, a reaction product is simultaneously generated at the interface between the complex oxide particles 7 and the matrix material 5, and the adhesion is further improved. For example, when the matrix material 5 is zirconia, ZrTiO ₄ , ZrNb ₂ O
₇ is also Y stable zirconia, Y ₂ TiO ₅ ,
Y ₃ NbO ₇ or the like is produced as a reaction product.

The form of precipitation of the composite oxide particles 7 constituting the agglomerated particles 6 is preferably a tabular grain or a needle-like structure, and the agglomerated particles 6 obtained by aggregating particles having such a shape are used as a matrix material (spraying). The growth of cracks is suppressed by precipitating between (solidified particles, etc.) 5. The tabular grains described here have a major axis of about 1 to 40 μm, a thickness of about 0.1 to 5 μm, and an aspect ratio of about 0.1 to 20, and are clearly found in ordinary spray-coagulated grains 5. It has a morphology different from such flat particles called lamellar structure.

The composite oxide particles 7 are not limited to tabular grains, and may be particles having a large aspect ratio and a small thickness, that is, needle-shaped particles. Complex oxide particles 7
May contain both tabular grains and acicular grains. The agglomerated particles 6 preferably have a structure in which such flat or needle-shaped composite oxide particles 7 are connected to each other and entangled with each other, whereby crack propagation can be suppressed more effectively.

The agglomerate diameter of the composite oxide particles 7 is not particularly limited, but may be the same as or smaller than the matrix particles (for example, the spray-solidified particles 5) constituting the ceramics layer 3. preferable. Specifically, the diameter of the agglomerated particles 6 is preferably in the range of 10 to 100 μm, and at such an agglomerated diameter, the crack growth suppressing effect is efficiently exhibited.

If the diameter of the agglomerated particles 6 is less than 10 μm, the effect of suppressing the cracking due to the agglomeration of the flat or acicular composite oxide particles 7 may not be sufficiently obtained.
If it exceeds μm, the bond between the matrix particles 5 mainly constituting the ceramics layer 3 becomes small, so that the crack suppressing effect may not be sufficiently exhibited. The diameter of the agglomerated particles 6 roughly depends on the individual particle diameters of the raw material powder of the composite oxide particles 7. Therefore, the particle diameter of the raw material powder is set according to the target aggregation diameter.

The aggregated particles 6 composed of the composite oxide particles 7 as described above are preferably dispersed and arranged in the range of about 1 to 50% (weight ratio) with respect to the matrix material 5. If the amount of the agglomerated particles 6 is less than 1% by weight with respect to the matrix material 5, it may not be possible to obtain a sufficient effect of suppressing the progress of cracks. On the other hand, if the amount of the aggregated particles 6 exceeds 50% by weight, the original characteristics of the matrix material 5 may be impaired. The amount of the agglomerated particles 6 is more preferably in the range of 5 to 40% by weight based on the matrix material 5.

The agglomerated particles 6 are dispersed inside the ceramic layer 3 at the sites where cracks propagate. Specifically, cracks are likely to propagate near the interface between the M-Cr-Al-Y alloy layer 2 and the ceramic layer 3 due to thermal stress.
In particular, it is preferable to allow the agglomerated particles 6 to exist in the range of about 300 μm. More preferably, the range is about 200 μm from the interface. In addition, when the ceramic layer 3 has a structure in which a vertical crack is formed to relax the stress, a lateral crack that causes peeling or falling may occur when the vertical crack is generated. It may occur at an unspecified position. In such a case, it is preferable that the agglomerated particles 6 as dispersed particles are present in the entire ceramic layer 3.

On the other hand, since the ceramic layer as the thermal barrier coating also peels off or falls off due to FOD or erosion damage, it is preferable to disperse the agglomerated particles 6 in the vicinity of the surface from the viewpoint of preventing these deteriorations. further,
When the composite oxide particles 7 are dispersed in the vicinity of the outer surface of the ceramic layer 3, microcracks are generated due to a volume change when a chemical reaction occurs, and the stress relaxation property of the ceramic layer 3 can be increased. By these, the erosion characteristics can be improved at the same time. In particular, the surface and the vicinity thereof may be exposed to a temperature higher than the heat treatment temperature for producing the composite oxide particles 7 for a long time. In such a case, by using TiO ₂ as a starting material, it reacts with zirconia forming the ceramics layer 3 to generate ZrTi ₂ O ₇ particles and the like, so that the erosion resistance can be further improved.

At this time, the kind of the complex oxide to be dispersed is not particularly limited, and M-Cr-Al-Y is used.
The particles dispersed near the interface with the alloy layer 2 and on the outer surface side of the ceramic layer 3 may have the same composition,
It may be of different composition. In particular, when a temperature gradient is generated in the ceramics layer 3 as in the thermal barrier coating, the high melting point composite oxide particles 7 are formed in the vicinity of the outer surface of the high temperature portion.
Aggregated particles 6 made of composite oxide particles 7 having a lower melting point than the former are dispersed in the vicinity of the interface in the low temperature part.
May be dispersed.

The matrix material 5 constituting the ceramics layer 3 is made of zirconium oxide, hafnium oxide, titanium oxide or the like having a large coefficient of thermal expansion in order to relieve thermal stress caused by a difference in coefficient of thermal expansion with the metal base material 1. It is desirable to use a Group 4A metal oxide or a rare earth oxide such as cerium oxide (CeO ₂ ). Particularly preferred is a compound containing a Group 4A metal oxide represented by ZrO ₂ as a main component, to which a rare earth oxide such as yttrium oxide or cerium oxide or an alkaline earth oxide is added.

In zirconium oxide (ZrO ₂ ), in order to suppress the phase transition caused by thermal history, a rare earth oxide or an alkaline earth oxide is added to form a partially stable tetragonal or cubic crystal. It is preferable to use stabilized zirconia or stabilized zirconia. On the other hand, if 1 to 30% of monoclinic zirconia is distributed inside the ceramic layer 3, fine cracks can be formed in the layer, which is preferable from the viewpoint of thermal stress relaxation. it can.

Although the ceramic layer 3 varies depending on the intended use of the heat-resistant member 4, it is preferable to coat the ceramic layer 3 in a thickness of about 50 to 500 μm. The structure of the ceramics layer 3 is not particularly limited, but when the ceramics layer 3 is coated under a single thermal spraying condition (for example, raw material powder), it is preferably formed under the condition that the surface roughness becomes large. . The surface roughness Rz after coating is preferably 50 μm or more, more preferably 52 μm or more. The hardness of the ceramic layer 3 in this case is 650H in Vickers hardness.
It is preferably v (load 200 gf, 30 seconds) or less. By these, the ceramics layer 3 excellent in the relaxation of thermal stress is obtained, and it is effective in extending the life of the heat resistant member 4.

When the ceramic layer 3 is formed by coating under a plurality of thermal spraying conditions, the M-Cr-Al-Y alloy layer 2 is formed.
In the range from the interface with and about 200 μm, the surface roughness is small (for example, Rz is 50 μm or less, more preferably
It is preferable that the coating is carried out in a state where the surface roughness is large as described above (for example, Rz is 50 μm or more). The initial hardness of the coating layer is preferably 650 Hv (load 200 gf, 30 seconds) or more in Vickers hardness.
According to such a ceramics layer 3, the occurrence of cracks can be suppressed, the relaxation of thermal stress can be enhanced, and the peeling life of the ceramics layer 3 can be improved. In particular, when the thickness of the ceramic layer 3 is 200 μm or more, it is desirable to apply the ceramic layer 3 having such a multilayer structure.

Next, a method of forming the above-mentioned ceramic layer 3 will be described. Although the case of forming the ceramics layer 3 by the thermal spraying method will be described here, when other film forming methods are applied, various conditions are set according to the selected film forming method. First, in the ceramic material forming the matrix of the ceramic layer 3, an alkaline earth element such as Mg or Ca and W, Ti, Ta or Mo.
And at least one metal element selected from Nb are mixed to prepare the thermal spray raw material powder. As the alkaline earth element and the metal element, for example, an oxide or a carbonate that becomes an oxide by heat treatment is used as a starting material, but a compound other than these can also be used. However, it is desirable to form the composite oxide particles 7 and the aggregated particles 6 thereof by adding an oxide, rather than a carbonate or the like that causes gas to be released.

The alkaline earth element and the metal element, which are the raw materials for forming the composite oxide particles 7, include (1) a compound containing the alkaline earth element and a compound containing the above metal element, or a mixture thereof to form a matrix. (2) A compound containing an alkaline earth element and a compound containing the metal element are reacted in advance to form a composite oxide, and the composite oxide powder is mixed into the ceramic material. ) Mixing with a matrix material by, for example, mixing a powder in which one of a compound containing an alkaline earth element and a compound containing the above metal element is dispersed inside ceramic particles forming a matrix, and the other compound powder. can do.

According to the above method (2), the precipitation reaction of the composite oxide particles 7 and the agglomerated particles 6 thereof is promoted, so that the heat treatment performed after the coating of the ceramic layer 3 is performed at a relatively low temperature and a short time. It can be done in time. Further, according to the method (3), the agglomerated particles 6 can be more uniformly dispersed in the ceramic layer 3 as compared with the methods (1) and (2).

When the ceramic layer 3 is made of zirconia, Mg-stabilized zirconia and Ca are used as a means for adding an alkaline earth oxide such as MgO or CaO.
Stabilized zirconia, Mg or Ca and stabilized zirconia whose crystal structure is stabilized by rare earth elements such as Y, MgO
It is also possible to use a complex oxide of CaO and zirconia. In particular, when Mg-stabilized zirconia or Ca-stabilized zirconia is used as a source of Mg or Ca, monoclinic zirconia is generated when Mg or Ca separates during the heat treatment process, which is desirable from the viewpoint of thermal stress relaxation. .

The composition of the thermal spraying raw material powder as described above depends on the amount of the agglomerated particles 6 present in the ceramic layer 3,
It is appropriately set according to the intended composition of the composite oxide particles 7. A typical composition is at least one selected from 0.1 to 30% by weight of MgO and 0.1 to 30% by weight of CaO (the total amount of alkaline earth oxides is 1 to 30% by weight).
%), 0.1 to 30% by weight of WO ₃ , 0.1 to 25% by weight of T
iO ₂ , 0.1-30 wt% Ta ₂ O ₅ , 0.1-30 wt%
MoO ₃ and 0.1 to 30% by weight of Nb ₂ O ₅ at least one kind (the total amount of metal oxide is 1 to 50% by weight).
%) And the balance is stabilized ZrO ₂ . The alkaline earth oxide may be SrO or BaO.

Regarding the raw material powder used at the time of coating, for example, in order not to reduce the adhesion efficiency of thermal spraying, the particle size is 1
~ 150 μm is preferable, and further 1 ~
It is desirable to be in the range of 125 μm. Furthermore, if heat treatment is performed before and after classifying a predetermined powder, it is possible to suppress the scattering of the powder when passing through a plasma flame during coating. Furthermore, the aggregate diameter of the aggregated particles 6 depends on the individual particle diameters of the raw material powder of the compound containing the alkaline earth oxide or the compound containing the metal element, which indirectly serves as the starting material of the composite oxide particles 7. .

Therefore, in the above method (1), the particle size of the compound powder containing the alkaline earth element, the compound powder containing the metal element, or the mixed powder thereof is appropriately adjusted according to the desired aggregate diameter. To do. For example, when dispersing relatively large agglomerated particles 6, it is preferable to use a powder having a particle size of, for example, 44 μm or more. When dispersing relatively small agglomerated particles 6, for example, 1 to 44 μm
It is preferable to use a powder having a particle size of a certain degree or a powder in which these are gently aggregated.

In the above-mentioned method (2), the particle size of the complex oxide powder formed by the reaction in advance is appropriately adjusted according to the target aggregate size. The specific particle size is the same as in the case of the method (1). Further, when applying the method of (3), one of the compound containing an alkaline earth element and the compound containing a metal element is mixed with the powder dispersed inside the ceramic particles, the other compound powder The particle size of the particles is adjusted, or the size of the substance to be dispersed inside the ceramic particles is appropriately adjusted. By these,
Aggregated particles 6 having a desired aggregate diameter are obtained.

Next, using the thermal spraying raw material powder as described above, the ceramic layer 3 is formed on the M-Cr-Al-Y alloy layer 2 formed on the metal substrate 1 by, for example, the plasma spraying method.
To form. It should be noted that, using a plurality of thermal spraying guns, the respective raw material powders (matrix material powder and starting raw material powder of the complex oxide particles 7, or a mixture of a part thereof) are sprayed from the respective thermal spraying guns and the ceramic layer 3 is formed. May be formed.

When heat treatment is applied to the obtained ceramic layer 3, for example, M dispersed in the ceramic layer 3 is dispersed.
Alkaline earth oxides such as gO and CaO and W, Ti, T
By reacting with an oxide of at least one metal element selected from a, Mo and Nb, a complex oxide as described above is produced. Further, sintering or the like occurs between such composite oxide particles (or particles added in advance as a composite oxide) to grow as tabular particles or acicular particles, and at the same time, these agglomerate and precipitate.

In this way, it is possible to obtain the ceramic layer 3 in which the aggregated particles 6 of the composite oxide particles 7 as shown in FIG. 2 are dispersed and arranged in the particles of the spray-coagulated particles 5 or between the particles. At this time, since the composite oxide particles 7 and the agglomerated particles 6 thereof are deposited by heat treatment after forming the ceramic layer 3, a coating method such as a thermal spraying method in which the initial particle shape is lost is applied. Even in the ceramic layer 3, the agglomerated particles 6 can be dispersed therein with good reproducibility.

The aggregated particles 6 composed of the composite oxide particles 7 are
As mentioned above, since the reaction and precipitation can be performed at a temperature of about 500 to 1400 ° C, the temperature condition during heat treatment is 5
It shall be in the range of 00 to 1400 ℃. Such a heat treatment temperature does not adversely affect the metal base material 1 made of a Ni-based superalloy, a Co-based superalloy, or the like. The heat treatment temperature is preferably set according to the type of complex oxide to be precipitated. That is, when producing a complex oxide having a high melting point, the heat treatment temperature is set to be high. Moreover, when the vapor pressure of the compound to be reacted with the alkaline earth oxide is high, the composite oxide can be produced at a relatively low temperature.
The heat treatment may be performed in the air, or may be performed in an inert atmosphere in consideration of deterioration of the metal substrate 1.

The aggregated particles 6 obtained by aggregating the composite oxide particles 7 as described above have the effect of suppressing the development of cracks inside the ceramic layer 3, and the forms of the composite oxide particles 7 and the aggregated particles 6 thereof. Is maintained even in a high temperature environment,
It is possible to effectively suppress the development of cracks in the ceramic layer 3. Based on such a crack growth suppressing effect, it is possible to stably suppress peeling of the ceramic layer 3 due to thermal stress generated when the heat resistant member 4 is used in a high temperature atmosphere. That is, the peeling resistance of the ceramic layer 3 can be significantly improved.

Further, since the composite oxide particles 7 are initially mixed in the matrix material of the ceramic layer 3 as a compound powder or the like and reacted by the heat treatment step after the ceramic layer 3 is formed, they are produced by a thermal spraying method. In the inside of the ceramic layer 3 to which the coating method in which the initial particle shape is lost is applied, the aggregated particles 6 of the composite oxide particles 7 having the effect of suppressing the progress of cracks as described above should be dispersed with good reproducibility. You can

[0061]

EXAMPLES Next, specific examples of the present invention will be described.

Example 1 First, a NiCoC having a thickness of about 150 μm was formed by a plasma spraying method on the surface of a round bar made of a Ni-base super heat-resistant alloy Mar-M247.
After forming the rAlY layer, (a) 8 wt% Y ₂ O ₃
Stabilized ZrO ₂ powder (particle size distribution: 44-80 μm), (b) M
Using a powder obtained by mixing gO and TiO ₂ in a weight ratio of 1: 2.5 (particle size distribution: 20 to 50 μm) in a weight ratio of 8: 2 as a thermal spray raw material powder, Thickness 250μ
A ceramic layer of m 3 was formed by coating.

Next, the sample on which the above-mentioned ceramic layer was formed was heated from room temperature to 1100 ° C. over 6 hours, then kept at that temperature for 2 hours, and then kept at 800 ° C. for 16 hours. Heat treatment was applied. When the constituent materials of the ceramic layer after the heat treatment were examined by the X-ray diffraction method, it was found that the constituent materials were mainly composed of Y-stabilized zirconia and MgTi ₂ O ₅ . Further, when SEM observation was carried out, it was confirmed that tabular grains made of MgTi ₂ O ₅ were aggregated and present between the zirconia sprayed grains mainly constituting the ceramics layer. These aggregate diameters are
It was about 20-60 μm. The sample thus obtained was subjected to the characteristic evaluation described below.

Example 2 A NiCoCrAlY layer having a thickness of about 140 μm was formed on the surface of a round bar made of Ni-base super heat-resistant alloy CMSX-2 by plasma spraying, and then (a) 8 wt% Y ₂ O ₃ stabilization was performed. Powder obtained by mixing (b) TiO ₂ powder (particle size distribution: ₂ to 10 μm) with 8.5% by weight of melt-pulverized powder (particle size distribution: 10 to 44 μm) prepared by previously adding 1.5% by weight of MgO to ZrO _2. Was used as a thermal spraying raw material powder to form a first ceramics layer having a thickness of 150 μm. On top of that, (c) a granulated and fired powder of 8 wt% Y ₂ O ₃ stabilized ZrO ₂ (particle size distribution: 10 to 44 μm) was used as a thermal spraying raw material powder, and a 100 μm thick second ceramic layer was formed. Was formed.

Next, the sample having the two-layered ceramic layer formed thereon was heat-treated at 1100 ° C. for 3 hours and then at 800 ° C. for 16 hours. X of the ceramic layer after heat treatment
When line diffraction and SEM observation were performed, NiCoC
It was confirmed that tabular grains of MgTi ₂ O ₅ were aggregated and present between the Y-stabilized zirconia sprayed grains in a region of 150 μm from the rAlY layer. Their aggregate diameter was about 10 to 30 μm. The sample thus obtained was subjected to the characteristic evaluation described below.

Comparative Example 1 A NiCoCrAlY layer having a thickness of about 140 μm was formed on the surface of a round bar made of Ni-base super heat-resistant alloy CMSX-2 by a plasma spraying method, and then 8 wt% Y ₂ O ₃ stabilized ZrO ₂ powder was prepared. A ceramic layer having a thickness of 250 μm was formed by using only (particle size distribution: 10 to 44 μm) as the thermal spraying raw material powder. When this sample was heat-treated at 1100 ° C for 3 hours and then at 800 ° C for 16 hours, no precipitation phase (acicular or tabular grains) was observed inside the ceramic layer. This sample was subjected to the characteristic evaluation shown below.

For each of the samples of Examples 1 and 2 and the sample of Comparative Example 1 described above, 250 M in an atmosphere of 850 ° C. simulating the atmosphere to which the members are exposed during gas turbine operation.
A stress of Pa was applied and a repeated heating test with room temperature was carried out in a 12-hour cycle. As a result, in each of the samples of Examples 1 and 2, the peeling of the ceramic layer did not occur even after 1000 cycles. When the cross section of the sample was observed after the test,
Some cracks were found to grow inside the Y-stabilized ZrO ₂ layer, but it was found that the progress of cracks was suppressed by tabular grains or aggregated particles of needle-shaped grains. On the other hand, in the sample of Comparative Example 1, the peeling of the zirconia layer started at 700 cycles, and the peeling completely occurred at 800 cycles.

Example 3 A NiCoCrAlY layer having a thickness of about 140 μm was formed on the surface of a round bar made of a Ni-base super heat-resistant alloy CMSX-2 by a plasma spraying method, and then (a) 8 wt% Y ₂ O ₃ stabilization was performed. ZrO ₂ powder and 8 wt% MgO-stabilized ZrO ₂ powder in a weight ratio of 1
Powder mixed at a ratio of 0: 2 (particle size distribution: 20-80 μm),
(b) 25% by weight of Nb ₂ O ₅ powder (particle size distribution: 10 to 20 μm)
The mixed powder is used as the thermal spray raw material powder, and the thickness is 250μ.
A ceramic layer of m 2 was formed.

Next, the sample on which the ceramic layer was formed was heat-treated at 1200 ° C. for 3 hours and subsequently at 800 ° C. for 16 hours. X is used as the constituent material of the ceramic layer after the heat treatment.
A line diffraction analysis revealed that it was mainly composed of Y-stabilized zirconia, monoclinic zirconia and MgNb ₂ O ₆ . Furthermore, when SEM observation was performed, M was observed between the Y-stabilized zirconia sprayed particles and the monoclinic zirconia sprayed particles mainly constituting the ceramics layer.
It was confirmed that tabular grains composed of gNb ₂ O ₆ were present in an aggregated state. The aggregate diameter of these was about 20 to 30 μm. The sample thus obtained was subjected to the characteristic evaluation described below.

Comparative Example 2 After a NiCoCrAlY layer having a thickness of about 140 μm was formed on the surface of a round bar made of Ni-base super heat-resistant alloy CMSX-2 by a plasma spraying method, 8 wt% Y ₂ O ₃ stabilized ZrO ₂ was added. A powder obtained by mixing 8% by weight of MgO-stabilized ZrO ₂ at a weight ratio of 10: 2 was used as a thermal spray raw material powder, and the thickness was 200 μm.
The ceramic layer of was formed.

Next, the sample on which the above-mentioned ceramic layer was formed was heat-treated at 1200 ° C. for 3 hours and subsequently at 800 ° C. for 16 hours. X is used as the constituent material of the ceramic layer after the heat treatment.
A line diffraction analysis revealed that it was mainly composed of Y-stabilized zirconia and monoclinic zirconia.
SEM observation of this ceramic layer was carried out, but no precipitation phase was found inside. The sample thus obtained was subjected to the characteristic evaluation described below.

For each of the samples of Example 3 and Comparative Example 2 described above, a stress of 250 MPa was applied in the atmosphere of 850 ° C. which simulates the atmosphere to which the members are exposed during the operation of the gas turbine, and a cycle of 12 hours was applied. A repeated heating test with room temperature was carried out. As a result, in the sample of Example 3, peeling of the ceramic layer did not occur even after 1000 cycles. When the cross section of the sample was observed after the test, Y-stabilized ZrO ₂
Although some cracks were found inside the layer,
It was found that the growth of cracks was suppressed by tabular grains and agglomerated grains of acicular grains. On the other hand, in the sample of Comparative Example 2, the ceramic layer peeled off in a short thermal cycle.

[0073]

As described above, according to the heat-resistant member of the present invention, it is possible to stably disperse agglomerated particles obtained by aggregating tabular particles or acicular particles inside the ceramic layer. It is possible to suppress peeling with good reproducibility. Therefore, it is possible to provide a heat-resistant member having significantly improved reliability and life.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a main part structure of a heat resistant member according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the structure of the aggregated particles shown in FIG.

[Explanation of symbols]

1 ... Metal base material 2 ... M-Cr-Al-Y alloy layer 3 ... Ceramics layer 4 ... Heat resistant material 5: Matrix material 6 ... Aggregated particles 7 ... Compound oxide particles

Claims (3)

(57) [Claims] 1. A metal base material made of an alloy containing at least one element selected from Ni, Co and Fe as a main component, and M-Cr-Al- coated on the metal base material.
Y alloy layer (where M represents at least one element selected from Ni, Co and Fe), and M-Cr-
A heat-resistant member comprising a ceramics layer provided on an Al-Y alloy layer, wherein the ceramics layer is a matrix material that mainly constitutes it, and a composite material that is dispersedly arranged in the matrix material and contains an alkaline earth element. A heat-resistant member comprising: aggregated particles of oxide particles. 2. The heat-resistant member according to claim 1, wherein the aggregated particles are alkaline earth elements and W, Ti, Ta,
A heat-resistant member comprising a composite oxide containing at least one metal element selected from Mo and Nb, and being particles obtained by aggregating at least one of tabular grains and acicular grains of the composite oxide. . 3. A metal base material made of an alloy containing at least one element selected from Ni, Co and Fe as a main component, and M-Cr-Al- coated on the metal base material.
Y alloy layer (where M represents at least one element selected from Ni, Co and Fe), and M-Cr-
In manufacturing a heat-resistant member including a ceramic layer formed by coating on an Al-Y alloy layer, a matrix material mainly constituting the ceramic layer, an alkaline earth element, W, Ti, Ta, Mo and Nb A step of forming the ceramic layer on the M-Cr-Al-Y alloy layer by coating with a raw material powder containing at least one metal element selected from A heat treatment at a temperature in the range, agglomerated particles obtained by aggregating the composite oxide particles containing the alkaline earth element and the metal element, dispersed in the ceramic layer, and a step of depositing, A method for manufacturing a heat resistant member.