JPH11264081A - Heat resistant member and production of heat resistant member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress oxidation and corrosion of a metal base material accompanied with a wear and damage of a MCrAlY alloy to contrive a long time in the case when the member is used for a long time in high temp. atmosphere. SOLUTION: The M-Cr-Al-Y alloy layer 2 (M is Ni, Co and Fe) is coated on the metal base material 1 consisting of an alloy consisting essentially of at least one kind selected among Ni, Co and Fe. A ceramic layer 3 having 1-50 μm average thickness is coated on the M-Cr-Al-Y alloy layer 2. The ceramic layer 3 is composed of the first ceramic layer 4 formed on the M-Cr-Al- Y alloy layer 2 and consisting essentially of alumina and chromia and the second ceramic layer 5 consisting of an oxide based ceramic (but, excluding alumina and chromia) becoming an oxygen supply source at the time of forming the first ceramic layer 4 and having oxygen dissociation function under a low oxygen atmosphere. The second ceramic layer 5 has >=650 Hv of Vickers hardness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant member used in a high-temperature environment and a method of manufacturing the same, and more particularly, to a heat-resistant member that suppresses deterioration of characteristics due to oxidation of a metal member and a method of manufacturing the same.

[0002]

2. Description of the Related Art In consideration of high-temperature strength, oxidation resistance, high-temperature corrosion resistance and the like, metal members constituting a heat engine such as a gas turbine, an aircraft or an automobile engine are made of a super-alloy containing Ni or Co as a main component. Alloys are used as substrates. In particular, in the case of moving and stationary blades for gas turbines and aircraft engines where the operating environment temperature exceeds 1000 ° C, in order to suppress deterioration due to oxidation of the metal base made of superalloy, especially strength reduction due to wall thinning and wear. M-Cr-Al-Y (M: Ni,
A metal coating layer made of an alloy (Co, Fe, etc.) is formed on a metal substrate, and an Al-rich layer (Al-rich layer) is further formed thereon by coating.

[0003] As described above, the surface of a metal substrate is conventionally covered with an M-Cr-Al-Y alloy layer or an Al-enriched layer for the purpose of suppressing strength reduction and wear due to thinning of the metal substrate. The conventional M-Cr-Al-
A heat-resistant member covered with a Y alloy layer or an Al-enriched layer has the following problems when used in a high-temperature environment for a long time.

That is, when used in a high-temperature atmosphere for a long time, the surface of the M-Cr-Al-Y alloy layer is oxidized, and a transition metal oxide such as alumina, nickel oxide, and cobalt oxide, and a composite oxidation of Al and a transition metal are used. An object (spinel) is generated. Such an oxide film is peeled off with the passage of time, and the M-Cr-Al-Y alloy layer is worn. When an oxide film containing a large amount of nickel oxide or cobalt oxide is generated, voids are generated at the interface between the oxide film and the M-Cr-Al-Y alloy layer, and the oxide film is easily peeled.

Therefore, in order to develop a long-life oxidation-resistant coating, the formation of oxides of transition metals such as Ni and Co is suppressed as much as possible, and a stable and dense coating under a high-temperature atmosphere is required to be an acid-resistant coating. It is desired to generate an oxide layer mainly composed of alumina that can be used as a protective oxide film. However, when the M-Cr-Al-Y alloy layer is simply oxidized in a high-temperature atmosphere, a plurality of oxides such as transition metal oxides and composite oxides are formed in addition to alumina, and a dense and uniform alumina layer is formed. Cannot be generated. For this reason,
M-Cr-Al-Y when used for a long time under high temperature environment
Since the oxidation of the alloy layer cannot be sufficiently suppressed, the generation, peeling, and regeneration of an oxide film are repeatedly performed, and M-Cr-Al
-The wear of the Y alloy layer proceeds.

[0006] Metal members constituting gas turbines, engines, and the like are sometimes used in an oxidizing atmosphere and in a highly corrosive environment including S and V. In such a case, instead of the oxide film mainly composed of alumina, an oxide film mainly composed of chromia is replaced with M-Cr-Al-Y.
It is known that by forming on an alloy layer, corrosion resistance to S, V, and the like is improved. However, at present, transition metal oxides such as Ni and Co are also formed at the same time as chromia, so that it is not possible to generate a uniform and dense oxide film mainly composed of chromia. Therefore, when used in a high-temperature corrosive environment for a long time, the M-Cr-Al-Y alloy layer deteriorates due to the intrusion of corrosive substances such as S and V, and the deterioration of the metal base material cannot be suppressed. There is.

Further, the Al-enriched layer is formed of M-Cr-Al-Y
Oxidation-resistant structures have been proposed to prevent the loss of the base material even when oxides are generated and peeled off by being formed directly on the alloy layer.However, since oxidation and peeling basically occur repeatedly, However, the effect of suppressing the oxidation of the substrate is not sufficient.
On the other hand, when used for a long time, the Al-enriched layer and M-Cr-
Element diffusion occurs due to a difference in composition between the Al-Y alloy layer and an embrittlement phase or void is generated in the M-Cr-Al-Y alloy layer, and the M-Cr-Al-Y alloy layer is easily peeled off. There are many disadvantages, such as a decrease in the amount of Al element in the vicinity of the outer surface, making it difficult to maintain oxidation resistance, and good results have not always been obtained.

A metal base made of a superalloy of Ni or Co and M
Regarding the interface with the -Cr-Al-Y alloy layer, when used in a high-temperature atmosphere for a long time, the diffusion of the component elements occurs due to the difference in these compositions, and the strength-enhancing phase of the metal substrate disappears, In addition, there is a problem that an embrittlement phase is generated. When considering only the oxidation resistance of the metal substrate, it is desirable to form an alumina layer having excellent oxidation resistance directly on the metal substrate, but a method for forming such an alumina layer has not been established. .

An alumina layer having excellent oxidation resistance, a chromia layer having excellent corrosion resistance, and the like are formed on a metal substrate or by using M-Cr-Al-
In the case of forming on the Y alloy layer, wear and damage due to collision of particles and deterioration of characteristics due to corrosive substances occur in an actual use environment such as a gas turbine. Therefore, erosion resistance and the like must be considered.

On the other hand, as the temperature rises further, M-Cr-A is used as an oxidation- and corrosion-resistant coating on a metal substrate.
Attempts have been made to coat a ceramic layer with a thickness of about 200 to 300 μm as a thermal barrier coating in addition to forming an l-Y alloy layer. However, when a member with a thermal barrier coating on its surface is used in a high-temperature atmosphere, the metallic member and the thermal barrier coating layer (ceramic layer)
There is a problem that thermal stress is generated due to a difference in thermal expansion coefficient between the ceramic layer and the ceramic layer, and the ceramic layer is easily peeled off. Therefore, even if an oxidation / corrosion resistant layer is formed at the interface between the metal bonding layer and the heat shield layer,
There has been a problem that the interface generation layer is damaged by the peeling of the ceramic layer and does not function sufficiently. Further, the conventional thermal barrier coating layer cannot suppress oxidation at the interface with the M-Cr-Al-Y alloy layer,
There is a problem that the effect of suppressing the oxidation resistance of the metal substrate by the Al-Y alloy layer is impaired.

[0011]

As described above, in a conventional heat-resistant member coated with an M-Cr-Al-Y alloy layer or an Al-enriched layer, the M Generation and peeling of an oxide film containing an oxide of a transition metal such as Ni or Co are repeated on the surface of the -Cr-Al-Y alloy layer, and it is not possible to sufficiently suppress the oxidation and strength reduction of the metal base material. There's a problem. This limits the life of the heat-resistant member.

For this reason, in the conventional heat-resistant member, the oxidation of the M—Cr—Al—Y alloy layer accompanied by the formation of oxides such as Ni and Co is suppressed by the MC
It has been an issue to suppress the wear and damage of the r-Al-Y alloy layer, and the oxidation and strength reduction of the metal base material for a long time. Further, it is desired to enhance the erosion characteristics in consideration of the actual use environment.

The present invention has been made to address such a problem, and has been developed for a long time by using M-Cr-Al-Y.
It is an object of the present invention to provide a heat-resistant member that maintains the characteristics of a metal base material for a long time and prolongs its life by suppressing oxidation and peeling of an alloy layer and improving erosion characteristics. Another object of the present invention is to substantially prevent the deterioration of the properties of the metal substrate due to element diffusion at the interface between the metal substrate and the M-Cr-Al-Y alloy layer, and to prevent the oxidation of the metal substrate. In order to maintain the performance, M
An object of the present invention is to provide a heat-resistant member that forms an oxidation-resistant layer in place of a Cr-Al-Y alloy layer, maintains the characteristics of a metal substrate for a long time, and extends the life.

[0014]

According to the first aspect of the present invention, a first heat-resistant member comprises a metal base made of an alloy containing at least one selected from Ni, Co and Fe. M-Cr coated on metal substrate
-Al-Y alloy layer (where M is Ni, Co and Fe
At least one element selected from the group consisting of
A ceramic layer having an average thickness of 1 to 50 μm coated directly on the Cr—Al—Y alloy layer or via an Al-enriched layer;
At least one selected from alumina and chromia formed on the r-Al-Y alloy layer or on the Al-rich layer
A first ceramic layer mainly composed of a seed;
And a second ceramic layer made of an oxide ceramic having oxygen dissociation ability (excluding alumina and chromia) and having a Vickers hardness of Hv 650 or more, which is present on the ceramic layer. And

The method for manufacturing a heat-resistant member according to the present invention is described in claim 3.
As described in the above, on the surface of a metal substrate made of an alloy containing at least one selected from Ni, Co and Fe,
MCrAlY alloy layer (where M is Ni, Co and F
e) at least one element selected from the group consisting of: e.) and directly using the sprayed raw material powder containing at least 50% of the powder produced by the melt-pulverization method on the M-Cr-Al-Y alloy layer. Alternatively, a step of forming an oxide-based ceramic layer having oxygen dissociating ability (excluding alumina and chromia) by a thermal spraying method via an Al-enriched layer, and a metal substrate on which the oxide-based ceramic layer is formed Is heat-treated in a low-oxygen atmosphere, and at least one member selected from alumina and chromia is interposed between the M-Cr-Al-Y alloy layer or the Al-enriched layer and the oxide-based ceramic layer.
Forming an oxide layer mainly composed of seeds.

Further, the second heat-resistant member of the present invention comprises:
As described in claim 2, a metal substrate made of an alloy containing at least one selected from Ni, Co and Fe, and a ceramic formed on the metal substrate directly or via an Al-enriched layer. A ceramic layer comprising: a first ceramic layer mainly composed of at least one selected from alumina and chromia formed on the metal base material or the Al-enriched layer; It is composed of oxide ceramics (excluding alumina and chromia) having oxygen dissociation ability present on the ceramics layer, and has a hardness of Vvs hardness of Hv
And a second ceramic layer having a thickness of 650 or more.

In the first heat-resistant member of the present invention, a heat treatment is performed while forming the second ceramic layer made of an oxide-based ceramic having oxygen dissociation ability or after forming the second ceramic layer. -A first ceramic layer (oxide layer) mainly composed of at least one selected from alumina and chromia is formed at the interface between the Al-Y alloy layer and the second ceramic layer.

The amount of oxygen used to form this oxide layer is
Controlled by the amount of oxygen dissociated from the oxide-based ceramics having oxygen dissociation ability, a dense oxide layer can be formed. Furthermore, oxides of transition metals such as Ni and Co, and their composite oxides Generation of an object or the like can be significantly suppressed. Since such an oxide layer has good oxidation resistance and corrosion resistance, wear and damage due to oxidation and peeling of the M-Cr-Al-Y layer, and corrosion due to sulfur and vanadium can be suppressed. .

Further, since the thickness of the ceramics layer is set in an appropriate range, peeling of the ceramics layer can be suppressed. Further, since the second ceramic layer existing on the surface layer has a Vickers hardness of Hv 650 or more, the erosion characteristics can be improved. In addition, the second ceramics layer also has a function of suppressing exfoliation accompanying the growth (such as an increase in film thickness) of the first ceramics layer (oxide layer) mainly composed of alumina or chromia. These make it possible to suppress the progress of oxidation and corrosion of the M-Cr-Al-Y layer.

Thus, in the first heat-resistant member,
Since the oxidation and corrosion of the M-Cr-Al-Y layer can be suppressed, the characteristics of the metal substrate can be stably maintained for a long time.

In the second heat-resistant member of the present invention, a second ceramics layer is formed directly on a metal base or via an Al-enriched layer, and the second ceramics layer and the metal base or Al-rich A first ceramic layer (oxide layer) mainly composed of alumina or chromia is formed at the interface with the oxide layer. This oxidized layer has good oxidation resistance and corrosion resistance similarly to the oxidized layer of the first heat-resistant member, and the second ceramic layer has good erosion characteristics and a function of suppressing separation due to the growth of the oxidized layer. As a result, it is possible to suppress characteristic deterioration due to oxidation and corrosion of the metal base material for a long time.

Further, since the second heat-resistant member has the oxidized layer formed directly on the metal substrate or via the Al-enriched layer, the element based on the composition difference between the metal substrate and the metal coating layer is formed. Does not cause diffusion. Therefore, it is possible to prevent a reduction in the strength of the metal base material due to the formation of an embrittlement phase or a void due to element diffusion. These make it possible to stably maintain the characteristics of the metal base material for a long time.

[0023]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view schematically showing the structure of the first embodiment of the heat-resistant member of the present invention. In the figure,
Reference numeral 1 denotes a metal substrate, and as the metal substrate 1, Ni, C
An alloy containing at least one selected from the group consisting of o and Fe as a main component may be mentioned, and various known heat-resistant alloys may be appropriately selected and used depending on the intended use. Practically, IN738, IN738LC, IN939, Mar
-M247, RENE80, CM-247, CMSX-
2, Ni-based superalloys such as CMSX-4 and FSX-41
4. It is effective to use a Co-based superalloy such as Mar-M509.

On the above-mentioned metal substrate 1, an M-Cr-Al-Y alloy layer (M is Ni,
2 (indicating at least one element selected from Co and Fe). This M-Cr-Al-Y
In order to obtain a function as a corrosion-resistant and oxidation-resistant metal coating, the alloy layer 2 is generally 0.1 to 20% by weight of Al, 10 to 10% by weight.
35% by weight of Cr, 0.1 to 5% by weight of Y, the balance being N
An alloy having a composition substantially composed of at least one M element selected from i, Co and Fe is used. Note that A
It is sufficient that l and Cr contain at least one of them, and other active metals such as Hf, Zr, and Ti can be used instead of Y. In some applications, Nb, T
a, W, etc. may be contained in the range of about 5% by weight or less. Here, the above alloys are collectively referred to as MC
It is called r-Al-Y alloy. Specifically, NiCoCrAl
Y alloy, CoNiCrAlY alloy, NiCrAlY alloy, CoCrAlY alloy, FeCrAlY alloy and the like are preferably used.

The M-Cr-Al-Y alloy layer 2 is formed by a thermal spraying method.
Although it can be formed by various film forming methods such as a PVD method and a CVD method, a thermal spraying method is most effective in practical use.
In particular, a reduced pressure spraying method (low vacuum spraying method) or a high-speed gas flame spraying method (HOVF) that can obtain a denser coating layer than the atmospheric spraying method.
It is preferable to apply the M-Cr-Al-Y alloy layer 2 by the entrained oxygen during the formation of the coating layer.
Internal oxidation can be suppressed. In addition, M-Cr-
The thickness of the Al—Y alloy layer 2 can be selected from the range of about 10 to 500 μm according to the application.
About 300 μm is appropriate.

Further, on the M-Cr-Al-Y alloy layer 2, a ceramic layer 3 having an average thickness in the range of 1 to 50 μm is formed. The ceramic layer 3 is M-
A first ceramic layer (oxide layer) 4 formed on the Cr-Al-Y alloy layer 2 and mainly composed of at least one selected from alumina (Al ₂ O ₃ ) and chromia (Cr ₂ O ₃ ); A second ceramic layer 5 made of an oxide ceramic (excluding alumina and chromia) present on the first ceramic layer 4 is provided, and these constitute a heat-resistant member 6.

The first ceramic layer 4 is made of M-Cr-A
It is composed of component elements (metal elements such as Al and Cr) in the l-Y alloy layer 2 and component elements (mainly oxygen) in the second ceramics layer 5, of which at least 50% by weight is selected from alumina and chromia. It is a ceramic layer composed of at least one kind. The amount of alumina, chromia, or a mixture thereof in the first ceramics layer 4 is preferably at least 75% by weight, more preferably at least 95% by weight.

Of the above-mentioned ceramic layers 3, the second ceramic layer 5 is made of an oxide ceramic material having an oxygen dissociating ability under a low oxygen atmosphere (low oxygen potential). During the membrane process,
Alternatively, by performing a heat treatment after forming the second ceramic layer 5, the first ceramic layer 4 mainly composed of alumina or chromia is formed by the M-Cr—Al—Y alloy layer 2 and the second ceramic layer 5. Formed at the interface.

That is, by using an oxide-based ceramic material having oxygen dissociation ability in a low oxygen atmosphere as the second ceramic layer 5 and applying a film formation or heat treatment under the conditions described later in detail, The first ceramics layer 4 which is a reaction product layer of Al and Cr among the constituents of the M-Cr-Al-Y alloy layer 2 with oxygen dissociated from the ceramics layer 5 of the second ceramics layer 5 is formed of M-Cr-Al- It can be selectively formed at the interface between the Y alloy layer 2 and the second ceramic layer 5, and the resulting first ceramic layer 4 can be further densified.

If the first ceramic layer 4 is too thick, the first ceramic layer 4 is liable to peel off due to a difference in the coefficient of thermal expansion from the M-Cr-Al-Y alloy layer 2.
The thinner the better, the more uniformly the surface of the -Y alloy layer 2 can be covered. Specifically, the average thickness is preferably 3.5 μm or less. However, when the average thickness of the first ceramics layer 4 is less than 0.01 μm, the M—Cr—Al—Y alloy layer 2
Practically 0.1μ because the uniformity of the surface decreases.
m or more.

The first ceramics layer 4 is preferably made of alumina particles or chromia particles having an average particle diameter in the range of 0.2 to 1.0 μm. According to such a ceramics layer 4, the metal member (the metal substrate 1 and the metal
-The growth rate of the Cr-Al-Y alloy layer 2) can be suppressed. The ceramic layer 4 in which such particles are coarsened can be obtained by using oxygen dissociated from the second ceramic layer 5 and reducing the thickness of the first ceramic layer 4 as an oxide layer. The thinning of the first ceramics layer 4 is also effective for suppressing the peeling of the ceramics layer 3.

The first ceramic layer 4, as will be described later, by appropriately setting to the substrate temperature and the heat treatment conditions at the time of film formation, YAG represented by _{xAl 2 O 3 · yY 2 O} 3, A composite oxide of Al and Y such as YAM can be contained. Since the composite oxide of Al and Y has a greater diffusion suppressing effect, the transition metal oxide such as Co or Ni or the M-Cr-Al-Y alloy layer 2 accompanying the formation of the composite oxide thereof is formed. Wear and damage can be more effectively suppressed.

The oxide-based ceramic material as the second ceramic layer 5 is an oxide material that easily dissociates oxygen under a low oxygen potential. In particular, a substance in which oxygen has a nonstoichiometric composition, specifically, zirconia, stabilized zirconia, titanium oxide, hafnium oxide, thorium oxide, rare earth metal oxide, molybdenum oxide, niobium oxide, tantalum oxide, alkaline earth metal oxide , These composite oxides,
It is also preferable to use a ceramic having a bichlore structure in which oxygen is regularly removed from the fluorite structure by 1/8.
Among these, stabilized zirconia is a particularly preferable material because it has a thermal expansion coefficient close to that of a metal member, is a high melting point material, and has excellent high-temperature stability.

The second ceramics layer 5 has a Vickers hardness (200 gf load, holding for 30 seconds / when an indenter is inserted into the sectional structure of the ceramics layer) and a hardness of Hv 650 or more. As described above, by forming the second ceramics layer 5 as the outermost layer as a high hardness layer, the erosion characteristics of the ceramics layer 3 as the coating layer can be greatly improved, and the life of the heat-resistant member 6 can be improved. I do. Such a high hardness ceramic layer 5 can be reproducibly formed by using a sprayed raw material powder containing 50% or more of a powder produced by a melt pulverization method when the ceramic layer 5 is formed by a thermal spraying method as described later. Obtainable.

As described above, the second ceramic layer 5 is used to improve the erosion characteristics of the ceramic layer 3 or to form the first ceramic layer 4 when used in a high-temperature atmosphere for a long time.
Although it has a function of suppressing the growth of (e.g., increase in film thickness), it is basically used for forming the dense first ceramic layer 4 mainly made of alumina or chromia. Is different from the ceramic layer as a thermal barrier coating. Therefore, the thickness of the second ceramics layer 5 only needs to be large enough to supply oxygen necessary for forming the first ceramics layer 4. In addition, if the thickness of the second ceramics layer 5 is too large, the generation of the first ceramics layer 4 becomes excessive, which causes the above-described inconvenience. Therefore, the thickness of the second ceramic layer 5 is set to 50 μm or less as the average thickness of the ceramic layer 3 including the first ceramic layer 4.

That is, the average thickness of the ceramic layer 3 is
If the thickness exceeds 50 μm, when the first ceramics layer 4 is formed by heat treatment after the formation of the second ceramics layer 5, the amount of supplied oxygen becomes excessive and the first ceramics layer 4 becomes too thick. . When the first ceramics layer 4 is formed simultaneously with the formation of the second ceramics layer 5, the first ceramics layer 4 is formed by heating the substrate, for example, so that the average thickness of the ceramics layer 3 exceeds 50 μm. In other words, if the film formation time of the second ceramics layer 5 is too long, the heat treatment effect at the time of film formation is increased and the first ceramics layer 4 becomes too thick,
This causes the above-described inconvenience. However, if the thickness of the ceramic layer 3 is too small, it is difficult to form an oxide layer as a dense coating, so the average thickness of the ceramic layer 3 is 1 μm or more.

The average thickness of the ceramic layer 3 not only contributes to the control of the amount of the first ceramic layer 4 formed, but also is important in preventing peeling of the first ceramic layer 4 and destruction inside the layer. From this point as well, the average thickness of the ceramic layer 3 needs to be 50 μm or less. That is, when the average thickness of the ceramic layer 3 exceeds 50 μm, M-Cr-
Due to the thermal stress generated due to the difference in the coefficient of thermal expansion from the Al—Y alloy layer 2, furthermore, the peeling and cracking of the ceramic layer 3, that is, the second ceramic layer 5, due to a decrease in the strength of itself and an increase in the fracture starting point. It is easy to occur. If the second ceramic layer 5 is peeled or cracked, the first ceramic layer 4 naturally tends to be peeled or the like, and the above-described oxidation of the transition metal such as Co or Ni cannot be suppressed. . From such a point, it is desirable that the average thickness of the ceramics layer 3 be 30 μm or less, at which a more favorable peeling / cracking suppressing effect can be obtained.

Second ceramic layer 5 in the present invention
Has a Vickers hardness of Hv 650 or more, which is clearly different from a ceramic layer as a conventional thermal barrier coating. That is, when the hardness of the conventional thermal barrier coating layer is set as described above and a coating layer of 250 μm or more required for thermal barrier is formed, the thermal barrier coating layer is easily peeled off.
On the other hand, in the present invention, since the average thickness of the ceramic layer 3 is 50 μm or less, peeling can be suppressed even if the hardness is Hv 650 or more. The present invention additionally improves the erosion resistance by increasing the hardness of the second ceramics layer 5 used for forming the dense first ceramics layer 4 mainly made of alumina or chromia. is there.

By forming a dense first ceramics layer 4 mainly made of alumina or chromia on the surface side of the M—Cr—Al—Y alloy layer 2,
Diffusion of transition metals such as Co and Ni from the r-Al-Y alloy layer 2 can be suppressed. That is, M-Cr-
Oxidation of a transition metal such as Co or Ni, which is a cause of exfoliation of the Al—Y alloy layer 2, is suppressed, and even when used for a long time,
It is possible to suppress the wear and damage of the M-Cr-Al-Y alloy layer 2 due to the formation of an oxide of a transition metal such as Ni or Ni or a composite oxide thereof.

When the first ceramics layer 4 is mainly made of alumina, it is possible to obtain a better effect of suppressing the oxidation of the M—Cr—Al—Y alloy layer 2. When the first ceramics layer 4 is mainly made of chromia, good corrosion resistance to a corrosive atmosphere containing S and V can be obtained. Further, the first ceramics layer 4 is mainly composed of a mixed oxide of chromia and alumina,
Alternatively, it may be composed of a composite oxide of chromia and alumina.

When only the oxidation resistance of the metal substrate 1 is considered, the first ceramic layer 4 is preferably a layer mainly composed of alumina, but is used in a highly corrosive environment including S and V. In this case, it is preferable to form a layer mainly composed of a mixed oxide of chromia and alumina or a composite oxide of chromia and alumina. Thus, a heat-resistant member having excellent corrosion resistance and oxidation resistance can be obtained.

As described above, the M—Cr—Al—Y alloy layer 2
By forming a dense first ceramics layer 4 mainly made of alumina or chromia on the surface side of
It is possible to suppress wear and tear due to oxidation and peeling of the Cr-Al-Y alloy layer 2 in an actual use atmosphere, or deterioration of characteristics of the M-Cr-Al-Y alloy layer 2 due to corrosion due to S and V. . Therefore, the function of suppressing deterioration of the metal substrate 1 due to oxidation or the like expected from the M-Cr-Al-Y alloy layer 2 is maintained for a long time, and the characteristics of the metal substrate 1 can be stably maintained for a long time. It becomes possible. That is, the service life of the heat-resistant member 6 can be extended.

In particular, when the device is used in a severer high-temperature environment where the oxidation reaction progresses violently, as shown in FIG. 2, an aluminum pack method is further formed on the M-Cr-Al-Y alloy layer 2. By forming an Al-enriched layer 7 by using, for example, and forming the ceramics layer 3 on the Al-enriched layer 7,
The first ceramics layer 4 mainly made of alumina may be generated.

The ceramic layer 3 in the heat-resistant member 6 of the above embodiment can be formed, for example, as follows. First, a method of forming the first ceramics layer 4 by performing a heat treatment after the formation of the second ceramics layer 5 will be described.

In this method, as shown in FIG.
On the M-Cr-Al-Y alloy layer 2, a second ceramics layer 5 made of an oxide ceramic material having an oxygen dissociation ability under a low oxygen potential is formed by, for example, a thermal spraying method.
When the second ceramics layer 5 is formed by the thermal spraying method, the substrate is preferably heated to 700 ° C. or less. Examples of the thermal spraying method include a plasma spraying method. In order to reduce the amount of oxygen in the second ceramics layer 5 serving as an oxygen supply source, the thermal spraying may be performed in a reduced pressure atmosphere to form a ceramics layer containing oxygen vacancies. Good.

It is desirable that the second ceramic layer 5 is formed by a thermal spraying method using a thermal spraying raw material powder containing at least 50% of a powder produced by a melt pulverizing method. The sprayed layer formed using the melt-pulverized powder can increase the hardness, specifically Vickers hardness (200 gf load, hold for 30 seconds)
Thus, a ceramic layer 5 having a hardness of Hv 650 or more can be obtained with good reproducibility. In order to produce the ceramic layer 5 having high hardness, it is desirable to use fine particles.

According to such a second ceramics layer 5, the erosion resistance can be improved, and the peeling and deterioration of the first ceramics layer 4 which affects the oxidation resistance and the erosion resistance can be suppressed. Becomes possible. In particular, from the viewpoint of improving the hardness, the higher the proportion of the melt-pulverized powder, the better. Particularly, it is desirable to prepare the thermal spray raw material powder using only the melt-pulverized powder. If the proportion of the melt-pulverized powder is less than 50%, the ceramic layer 5 satisfying the above-described hardness cannot be obtained with good reproducibility. In particular, when a fine powder having an average particle diameter of 44 μm or less is used, the hardness can be further increased.

Next, a heat treatment is performed on the second ceramics layer 5 in a low oxygen atmosphere, and as shown in FIG. 3B, the M—Cr—Al—Y alloy layer 2 and the second On the interface with the ceramic layer 5, the first ceramic layer 4 is formed as an oxide layer. As described above, the heat treatment is performed on the second ceramics layer 5 in a low oxygen atmosphere, and oxygen is supplied from the second ceramics layer 5 to form the first ceramics layer 4 as a product of the interfacial reaction. Dense alumina and chromia can be selectively obtained.

The heat treatment atmosphere for forming the first ceramic layer 4 is preferably in a vacuum of 1 Pa or less. If the atmospheric pressure during the heat treatment exceeds 1 Pa, oxidation may occur in the M-Cr-Al-Y alloy layer 2 due to oxygen from the atmosphere. Thereby, M-Cr-Al-Y
There is a possibility that an oxide of a transition metal such as Ni or Co, which causes peeling of the alloy layer 2, may be generated. The atmosphere during the heat treatment is in the range of 0.1 to 10 ^-4 Pa, which can form the denser first ceramics layer 4 and can more effectively suppress the oxidation in the M-Cr-Al-Y alloy layer 2. It is desirable to use a low pressure atmosphere.

The heat treatment temperature is selected depending on the components constituting the first ceramics layer. When forming the first ceramics layer 4 mainly made of alumina, the heat treatment temperature is 800 ° C.
The temperature is preferably set to not less than ° C. If the heat treatment temperature is lower than 800 ° C., the generation amount of oxides other than alumina may increase. At this time, particularly by setting the heat treatment temperature to 1100 ° C. or higher, the first ceramics layer 4 can contain the composite oxide of Al and Y as described above,
Generation of transition metal oxides such as Co and Ni can be more effectively suppressed. The heat treatment time is not particularly limited, but is preferably about 1 to 100 hours. Note that this heat treatment may be performed as one step of a multi-step heat treatment (solution treatment + aging treatment) performed to maintain the characteristics of the metal substrate 1.

On the other hand, when forming the first ceramic layer 4 mainly composed of a mixed oxide of chromia and alumina or a composite oxide of chromia and alumina, the heat treatment temperature should be in the range of 500 to 900 ° C. Is preferred. If the heat treatment temperature is lower than 500 ° C., the amount of generated oxide is insufficient, while if it exceeds 900 ° C., the amount of generated alumina increases and the amount of chromia decreases. By controlling the heat treatment temperature at this time, the first ceramics layer 4 can be a layer mainly composed of chromia. Since the heat treatment temperature is lower than the multi-step heat treatment temperature for maintaining the characteristics of the metal substrate 1, the heat treatment for forming the first ceramics layer 4 is performed before the multi-step heat treatment. Is carried out. Although the heat treatment time is not particularly limited, 1
It is preferably set to about 10 hours.

According to the method of forming the first ceramic layer 4 by performing the heat treatment after the formation of the second ceramic layer 5, it is easy to control the thickness of the first ceramic layer 4. This is particularly effective when the oxide layer 4 mainly composed of a minimum of dense alumina or chromia is formed.

The thickness of the oxide layer 4 formed during the heat treatment and the particle diameter of alumina and chromia constituting the oxide layer 4 depend on the thickness of the first ceramic layer 4 having oxygen dissociation ability and the oxygen potential at the time of coating. Dependent. By reducing the initial thickness of the oxide layer 4 and increasing the particle size of alumina or chromia, it is possible to suppress the growth of oxide when kept in a high-temperature atmosphere. In particular, when the amount of dissociated oxygen is reduced by coating the ceramic layer 4 having a small thickness, the thickness of the oxide layer 4 can be suppressed small, and the particle diameter of alumina or chromia can be increased. As a result, peeling and cracking of the ceramic layer 3 are less likely to occur, and the function of the M-Cr-Al-Y alloy layer 2 can be maintained for a long period of time.

The second ceramics layer 5 can be formed simultaneously with the formation of the first ceramics layer 4.
When the thermal spraying method is applied, it is difficult to control the first ceramics layer 4 formed simultaneously with the formation of the second ceramics layer 5, so that the above-described method of performing heat treatment after the film formation is applied. preferable.

The second ceramics layer 5 in the present invention is not necessarily limited to the one formed by the thermal spraying method. For example, if the above hardness can be satisfied, the second ceramics layer 5 may be formed by the PVD method or the sputtering method. , A CVD method or the like may be applied. In this case, since the first ceramics layer 4 cannot be formed only by coating the second ceramics layer 5 by the PVD method or the like, the second ceramics layer 5 is formed while heating the metal substrate 1. I do. The heating temperature is
The temperature is preferably set to 700 ° C. or higher. Further, it is desirable to coat while heating to 900 ° C. or more, so that a first ceramics layer 4 made of coarse alumina particles or the like is formed directly on the M—Cr—Al—Y alloy layer 2 to diffuse oxygen. Can be suppressed.

In each of the embodiments described above, the case where the ceramic layer 3 is formed on the M—Cr—Al—Y alloy layer 2 has been described, but the ceramic layer 3 according to the present invention, that is, the dense layer mainly composed of alumina or chromia, is used. First
The ceramic layer 3 composed of the ceramic layer 4 and the second ceramic layer 5 serving as an oxygen supply source can be directly formed on the metal substrate 1 as shown in FIG.

For example, CMSX-2,
When using a single crystal substrate such as CMSX-4,
When an M-Cr-Al-Y alloy layer having a different composition is coated and formed and used for a long time in a high-temperature atmosphere, the structure near the surface of the metal substrate 1 may be recrystallized due to diffusion of elements, and the substrate strength may be reduced. is there. In such a case, the ceramic layer 3 mainly composed of the dense first ceramic layer 4 mainly composed of alumina or chromia and the second ceramic layer 5 serving as an oxygen supply source is directly formed on the metal substrate 1. You may do so.

When used in a severer high temperature environment, as shown in FIG. 5, an Al-enriched layer 7 is further formed on the metal substrate 1 by an aluminum pack method or the like. By forming the ceramic layer 3 on the first ceramic layer 7, the first ceramic layer 4 mainly made of alumina may be generated.

As shown in FIG. 4, when the ceramic layer 3 is formed directly on the metal substrate 1, the first ceramic layer 4 is formed by the constituent elements of the metal substrate 1. Further, as shown in FIG. 5, when the ceramic layer 3 is formed via the Al-enriched layer 7 provided on the metal base 1,
The first ceramic layer 4 mainly made of alumina is generated by the Al-enriched layer 7. The specific conditions and production conditions of each layer are the same as in the case of forming on the M-Cr-Al-Y alloy layer 2, but the first ceramics layer 4 mainly made of alumina or chromia and the metal substrate 1 In the case of direct contact, it is necessary to sufficiently consider the relaxation of thermal stress by controlling the thickness of each layer.

[0061]

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

Example 1 NiC having a thickness of 150 μm was formed on a Ni-based superalloy by a low vacuum spraying method.
After forming the oCrAlY alloy layer, the thickness of the
An 8% by weight Y ₂ O ₃ stabilized zirconia layer of μm was coated. In forming the Y-stabilized zirconia layer,
Granulated powder (particle size: 10 to 44 μm) and melt-pulverized powder (particle size: 10
~ 44μm), the ratio of granulated powder and melt-pulverized powder is 0 /
100 (sample A), 10/90 (sample B), 20/80 (sample C), 30/7
0 (sample D), 40/60 (sample E), 50/50 (sample F), 60/40
(Sample G), 70/30 (Sample H), 80/20 (Sample I), 90/10
Using a mixed powder of (Sample J) and 100/0 (Sample K), a Y-stabilized zirconia layer was formed, respectively. After this, each sample is placed in a low oxygen potential atmosphere at
Time heat treatment was applied.

When a cross section of each of the obtained samples was observed by SEM-EDX, NiCoCr
At the interface between the AlY layer and the Y-stabilized zirconia layer, an oxide layer mainly composed of alumina (particle diameter: 0.2 to 0.5 μm) was formed. When the hardness of the Y-stabilized zirconia layer of each sample was measured, sample A was Hv 780, sample B was Hv 730,
Sample C is Hv 720, Sample D is Hv 710, Sample E is Hv 680, Sample F is Hv 660, Sample G is Hv 620, Sample H is Hv 580, Sample I is Hv 540, Sample J is Hv 510, Sample K. Was Hv 480.

Alumina powder was added to each of the above samples.
While feeding at 25 g / mm, a test involving repeated heat treatment was performed with one cycle of 1000 ° C. × 8 hours + 100 ° C. × 1 hour. As a result, in Samples A to F in which the proportion of the melt-pulverized powder was large, no change in appearance was observed at all, and no damage occurred. In addition, the internal oxidation of the NiCoCrAlY layer did not progress, and it was confirmed that the oxide layer mainly composed of alumina functions well as the oxidation-resistant suppressing layer. On the other hand, in Samples G to K in which the proportion of the granulated and fired powder is large, Y
Peeling occurs in the stabilized zirconia layer and NiCoCrAl
Oxidation and peeling of the Y layer occurred remarkably.

Example 2 An NiCoCrAlY alloy layer having a thickness of about 150 μm was formed on the surface of a Ni-base superalloy by low-vacuum thermal spraying, and then 8 weight by an atmospheric thermal spraying method using a melt-pulverized powder (particle size: 10 to 44 μm).
% Y ₂ O ₃ stabilized zirconia layer was formed. At this time, Y
Sample A in which the thickness of the stabilized zirconia layer was 40 μm;
Samples B each having a stabilized zirconia layer thickness of 200 μm were prepared. Thereafter, each sample was subjected to a heat treatment at 1000 ° C. for 5 hours in a low oxygen potential atmosphere of 0.001 atm.

When the cross section of each of the obtained samples was observed by SEM-EDX, NiCoCr
At the interface between the AlY layer and the Y-stabilized zirconia layer, an oxide layer mainly composed of alumina was formed. In Sample A, the thickness of the oxide layer was 0.8 μm (particle diameter: 0.4 μm). Was 1.5 μm (particle size 0.1 μm). Also,
When the hardness of the Y-stabilized zirconia layer of each sample was measured, sample A was Hv 700 and sample B was Hv 760.

Each of the above-mentioned samples was subjected to a test involving repeated heat treatment in which one cycle was 1000 ° C. × 8 hours + 100 ° C. × 1 hour. As a result, in Sample A corresponding to the example of the present invention, no change in appearance was observed at all, and no damage occurred. In addition, the internal oxidation of the NiCoCrAlY layer did not progress, and it was confirmed that the oxide layer mainly composed of alumina functions well as the oxidation-resistant suppressing layer. On the other hand, in Sample B as a comparative example, the peeling of the Y-stabilized zirconia layer partially occurred after 200 cycles, and the oxidation and peeling of the NiCoCrAlY layer significantly occurred.

Example 3 Samples A and B manufactured under the same conditions as in Example 2 described above
Was first kept in an air atmosphere at 1000 ° C. for 5000 hours. When the film thickness of the oxide layer after the holding was examined, the thickness of the oxide layer was 4 μm in Sample A and 10 μm in Sample B. 1000 ° C x 8 hours + 1 for each sample after heat treatment
A test involving repeated heat treatment with one cycle of 00 ° C. × 1 hour was performed.

As a result, in the sample A corresponding to the example of the present invention, no change in appearance was observed even after more than 200 cycles, and no damage occurred. On the other hand, in Sample B as a comparative example, the peeling of the Y-stabilized zirconia layer partially occurred after more than 50 cycles, and the oxidation and peeling of the NiCoCrAlY layer significantly occurred.

Example 4 NiCoCrA having a thickness of about 150 μm was formed on the surface of a Ni-base superalloy.
After forming an 1Y alloy layer and further performing an aluminum pack treatment to form an Al-enriched layer having an average thickness of 20 μm, 8 wt% Y ₂ was formed by an air spray method using a melt-pulverized powder (particle size: 10 to 44 μm). An O ₃ stabilized zirconia layer was formed. On this occasion,
The thickness of the Y-stabilized zirconia layer was 40 μm. After this,
Heat treatment was performed at 1000 ° C. for 5 hours in a low oxygen potential atmosphere of 0.001 atm.

When a cross section of the obtained sample was observed by SEM-EDX, an oxide layer made of alumina was formed at the interface between the Al-enriched layer and the Y-stabilized zirconia layer. The hardness of the Y-stabilized zirconia layer was Hv720. Such a sample was subjected to a test involving repeated heat treatment in which one cycle was 1000 ° C. × 8 hours + 100 ° C. × 1 hour. As a result, no change in appearance was observed, and no damage occurred.

Example 5 An Al-enriched layer having an average thickness of 5 μm was formed by subjecting a surface of a Ni-base superalloy to aluminum pack treatment, and then subjected to an atmospheric spraying method using a melt-pulverized powder (particle size: 10 to 44 μm). 8% by weight Y
_{A 2} O ₃ stabilized zirconia layer was formed. At this time, a sample A in which the thickness of the Y-stabilized zirconia layer was 40 μm and a sample B in which the thickness of the Y-stabilized zirconia layer was 200 μm were prepared. Thereafter, each sample was subjected to a heat treatment at 1000 ° C. for 5 hours in a low oxygen potential atmosphere of 0.001 atm.

When the cross section of each of the obtained samples was observed by SEM-EDX, NiCoCr
An oxide layer mainly composed of alumina was formed at the interface between the AlY layer and the Y-stabilized zirconia layer. When the hardness of the Y-stabilized zirconia layer of each sample was measured, the sample A was Hv 730 and the sample B was Hv 750.

Each of the above-mentioned samples was subjected to a test involving repeated heat treatment in which one cycle consisted of 1000 ° C. × 8 hours + 100 ° C. × 1 hour. As a result, in Sample A corresponding to the example of the present invention, no change in appearance was observed at all, and no damage occurred. In addition, the internal oxidation of the NiCoCrAlY layer did not progress, and it was confirmed that the oxide layer mainly composed of alumina functions well as the oxidation-resistant suppressing layer. On the other hand, in the sample B as a comparative example, the peeling of the Y-stabilized zirconia layer partially occurred at the time exceeding 40 cycles,
Oxidation of the Ni-based superalloy had occurred.

[0075]

As described above, according to the heat-resistant member of the present invention, even if the heat-resistant member is used for a long time in a high-temperature atmosphere, deterioration due to oxidation or corrosion of the metal substrate can be effectively suppressed. The reliability and life of the heat-resistant member can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a structure of an embodiment of a first heat-resistant member of the present invention.

FIG. 2 is a sectional view showing a modification of the heat-resistant member shown in FIG.

FIG. 3 is a sectional view showing an example of a manufacturing process of the heat-resistant member shown in FIG.

FIG. 4 is a cross-sectional view schematically illustrating a structure of an embodiment of a second heat-resistant member of the present invention.

FIG. 5 is a sectional view showing a modification of the heat-resistant member shown in FIG.

[Description of Signs] 1 ... Metal base material 2 ... M-Cr-Al-Y alloy layer 3 ... Ceramic layer 4 ... First ceramic layer 5 ... Second ceramic layer 6 ... Heat resistant member 7 ...... Al-rich layer

Continued on the front page (72) Inventor Hiroki Inagaki 1 Toshiba-cho, Komukai-Toshiba-cho, Saisaki-ku, Kawasaki-shi, Kanagawa Inside the R & D Center of Toshiba Corporation

Claims (3)

[Claims] 1. A metal base made of an alloy containing at least one selected from Ni, Co and Fe, and an M-Cr-Al-Y alloy layer (M is a coating) formed on the metal base. And at least one element selected from the group consisting of Ni, Co and Fe), and an average thickness of 1 to 50 μm, which is formed directly or via an Al-enriched layer on the M-Cr-Al-Y alloy layer. A ceramic layer, wherein the ceramic layer is a first ceramic mainly composed of at least one selected from alumina and chromia formed on the M-Cr-Al-Y alloy layer or the Al-enriched layer. An oxide-based ceramic having oxygen dissociation ability (excluding alumina and chromia) present on the first ceramic layer,
And a second ceramics layer having a Vickers hardness of Hv 650 or more. 2. A metal base made of an alloy containing at least one selected from Ni, Co and Fe, and a ceramic layer formed on the metal base either directly or through an Al-enriched layer. The ceramic layer may be formed on the metal substrate or the Al.
A first ceramics layer mainly composed of at least one selected from alumina and chromia formed on the enriched layer, and an oxide-based ceramic having oxygen dissociation ability present on the first ceramics layer (excluding alumina And a second ceramic layer having a Vickers hardness of Hv 650 or more. 3. A metal substrate comprising an alloy containing at least one selected from Ni, Co and Fe,
A step of forming a Cr-Al-Y alloy layer (where M represents at least one element selected from Ni, Co and Fe); and a spraying raw material powder containing at least 50% of a powder produced by a melt-pulverization method. An oxide ceramic layer (excluding alumina and chromia) having oxygen dissociation ability is formed on the M-Cr-Al-Y alloy layer by thermal spraying directly or via an Al-enriched layer. Subjecting the metal substrate on which the oxide-based ceramics layer is formed to a heat treatment in a low oxygen atmosphere, wherein the M-Cr-Al-Y
Producing a oxidized layer mainly composed of at least one selected from alumina and chromia between the alloy layer or the Al-enriched layer and the oxide-based ceramic layer. .