JPH10273787A - Heat resistant member and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] An object of the present invention is to prevent the peeling of a ceramic layer for a long time, thereby improving the adhesion between the layers and improving the acid-resistant life. A substrate 1 made of an alloy containing at least one element selected from Ni, Co, and Fe as a main component, and an MCrAlY alloy layer (M = N
i, Co, Fe) 2, on which is mainly composed of stabilized zirconia, with the balance being magnesium compounds and W, T
By heat-treating a heat-resistant member composed of a ceramic layer 3 in which a compound containing at least one element of i, B, Ta, Te, Ge, and V is dispersed, tabular particles composed of a composite oxide containing Mg in ceramics 4 to obtain a heat-resistant member having a large crack-suppressing power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 As the operating temperature of equipment increases with the aim of increasing the efficiency of high-temperature equipment such as gas turbines for power generation and engines, materials used for equipment components include:
Even higher levels of properties, such as high temperature strength, high temperature corrosion and oxidation resistance, are required. Therefore, MCrAlY (M is N
(i, Co, Fe, etc.) A technology for applying corrosion-resistant and oxidation-resistant metal coatings made of alloys, etc., has been developed.
It has already been widely applied as an indispensable technology in stationary vanes and the like. In addition, with the trend toward higher temperatures, thermal barrier coating technology that protects the metal material inside by coating a ceramic layer with low thermal conductivity on the surface of the corrosion-resistant and oxidation-resistant metal coating layer is also being put into practical use. .

However, when a metal member and a ceramic coating layer member are used in a high-temperature atmosphere like a thermal barrier coating, thermal stress is generated due to a difference in thermal expansion coefficient between the two members, and the ceramic coating layer is peeled off. there were. Since the ceramic coating layer is peeled off, the ceramic coating layer cannot be used continuously for a long time in a high temperature atmosphere, and a ceramic coating layer that is resistant to peeling has been desired from the viewpoint of extending the life of the thermal barrier coating member.

[0004]

As described above, in a conventional heat-resistant member in which a ceramic layer is coated on a metal member, the ceramic layer is easily peeled off during a long operation, and the protection of the metal layer is long. There was a problem that it could not be maintained sufficiently over time.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem, and it is an object of the present invention to provide a heat-resistant member which sufficiently suppresses peeling of a ceramic layer for a long time and achieves a long life. .

[0006]

Means for Solving the Problems The first invention of the present application is based on N
a base material made of an alloy mainly containing at least one element selected from i, Co and Fe, and a ceramic layer formed on the surface of the base material and having dispersed therein flat particles formed on the MCrAlY alloy layer And a heat-resistant member having:

In a second aspect of the present invention, the tabular grains are formed of Mg.
The heat-resistant member according to the first aspect of the present invention, which is a composite oxide containing: In the third invention of the present application, the ceramic layer is
The heat-resistant member according to the first aspect of the present invention, which is at least one selected from stabilized zirconia and partially stabilized zirconia stabilized with a rare earth oxide or an alkaline earth metal oxide.

The fourth invention of the present application is directed to an MCrAlY alloy layer (M is at least one selected from Ni, Co and Fe).
Element), and Mg and an element which reacts with Mg to form a composite oxide on the surface of a base material made of an alloy mainly containing at least one element selected from Ni, Fe and Fe. This is a method for manufacturing a heat-resistant member, comprising a step of forming a ceramic layer using ceramic raw material powder, and a step of heating so as to form flat particles of a composite oxide containing Mg in the ceramic layer.

According to the present invention, by dispersing plate-like particles in ceramics constituting a part of the heat-resistant member, it is possible to suppress the crack growth of the heat-resistant member. Conventionally, in fields other than heat-resistant members, a technique of suppressing crack growth of ceramics by dispersing tabular grains in ceramics has been used.

However, according to the conventional method, tabular grains and the like are mixed and dispersed to form a composite, or high temperature (1)
Heat treatment at 600 ° C. or higher is necessary, and such heat treatment cannot be performed on a heat-resistant member having a thermal barrier coating layer produced by a thermal spraying method because such a heat treatment adversely affects a metal member. The inventors of the present application have conducted intensive studies on a method of dispersing tabular grains in ceramics that can be produced by using a thermal spraying method, and have reached the present invention.

That is, MgO and mainly W, Ti,
When heat treatment is performed in a state where a compound containing at least one element of B, Ta, Te, Ge, V, and Mo is mixed, a composite oxide of Mg and a dispersive element such as M
It has been found that gWO ₄ and MgTi ₂ O ₅ can be produced, and that these oxides form tabular grains by selecting heat treatment conditions.

The tabular grains of the present invention have an aspect ratio of 1
And particles having a major axis of 1 to 40 μm and a thickness of 0.1 to 5 μm, which are different from flat particles called lamellar structures as found in ordinary thermal spray solidified particles. The form of the tabular dispersed particles of the present invention is not limited to tabular grains, but may be, for example, particles having a large aspect ratio and a small thickness, that is, acicular particles. Further, the dispersion position is not particularly limited. However, it is preferable that the particles are dispersed between the spray-melted and solidified particles because crack propagation that propagates in the ceramic layer constituting the matrix can be suppressed. Even if the acicular dispersed particles are aggregated, such a dispersion form may be used since stress relaxation occurs by breaking the aggregated particles when the crack passes through the aggregated particles.

[0013] When the density of these particles in the dispersion state on the surface of the coating layer is high, the erosion characteristics of the thermal barrier coating member can be improved. In the present invention, tabular grains can be generated inside the coating layer by heat treatment as described above. Therefore, any material that forms a composite oxide with MgO by heat treatment may be used. For example, ceramics serving as a matrix include MgO and mainly W, T
Using particles composed of a compound containing at least one element of i, B, Ta, Te, Ge, V, and Mo as a thermal spraying material powder, a ceramic coating layer is coated by a thermal spraying method, and then heat treatment is performed. , Ti, B, Ta, Te, Ge,
Tabular grains composed of a composite oxide of at least one element of V and Mo and Mg can be generated inside the ceramic coating layer, and the growth of cracks that propagate inside the ceramic layer forming the matrix can be suppressed. It becomes possible.

[0014]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a metal substrate, and as the metal substrate 1, a heat-resistant alloy mainly containing at least one element selected from NI, Co, and Fe is used. A known heat-resistant alloy can be appropriately selected and used. Practically, IN738, IN738
LC, IN939, Mar-M247, RENE80, CM-247, CMSX-2, CMSX-
4 such as Ni-base super heat-resistant alloys and Co such as FSX-414 and Mar-M509.
It is effective to use a base superalloy. An MCrAlY alloy layer 2 is formed on the surface of the metal substrate 1 as a corrosion-resistant and oxidation-resistant metal coating layer. This MCrA
The 1Y alloy layer 2 includes at least one element such as Ni, Co, and Fe, at least one element of Cr and Al,
An alloy composed of at least one of active metals such as Hf, Zr, and Ti is used. For example, NiCoCrAl
Y, CoNiCrAlY, NiCrAlY, CoCrA
lY, FeCrAlY and the like.

Further, a ceramic layer 3 is formed on the surface of the MCrAlY alloy layer 2, and dispersed particles 4 are present inside the ceramic layer 3. The ceramic coating layer 3 is composed mainly of a so-called Group 4a metal oxide such as Zr oxide, Hf oxide and Ti oxide, and contains a rare earth oxide such as Y oxide and Ce oxide or an alkaline earth oxide. Conceivable. The dispersed particles are compound particles composed of MgO and at least one element of W, Ti, B, Ta, Te, Ge, V, and Mo. MgO and other compound elements used as the dispersed particles may be dispersed separately, or may be mixed with the matrix particle powder in advance by mixing the dispersed particles so that both can be uniformly dispersed. Mg, mainly W, T
At least one of the compounds composed of at least one element of i, B, Ta, Te, Ge, V and Mo may be coated after being dispersed in the ceramic particles constituting the matrix. .

These components constitute the heat-resistant member 5. When the heat-resistant member thus manufactured is heat-treated,
Dispersed MgO and mainly W, Ti, B, Ta, T
A compound composed of at least one element of e, Ge, and V reacts to generate a composite oxide with Mg.
The resulting composite oxide is determined by the compound dispersed with MgO. For example, MgWO _3, MgTiO _3,
MgTi ₂ O ₅ , Mg ₂ TiO ₄ , MgB ₄ O ₇ , Mg
₂ B ₂ O ₅ , Mg ₃ B ₂ O ₆ , MgTa ₂ O ₆ , MgG
eO ₃ , Mg ₂ GeO ₄ , Mg ₄ GeO ₆ , MgTe ₂
O ₅ , Mg ₃ V ₄ O ₁₃ , Mg ₂ Mo ₃ O ₁₁ , MgMoO
₄ . The heat treatment temperature varies slightly depending on the type of the composite oxide to be deposited,
The temperature is set to 1400 ° C., and the atmosphere may be air, but may be generated in an inert atmosphere in consideration of deterioration of the metal member.

In particular, a high temperature atmosphere (850 ° C.)
For those members that are used for a long time, MgWO ₃ , Mg ₃
(VO ₄ ) ₂ , MgB ₄ O ₇ , Mg ₂ B ₂ O ₅ , Mg ₃
B ₂ O ₆ , Mg ₂ Mo ₃ O ₁₁ , MgMoO ₄ , Mg ₂ T
iO ₄ , MgTiO ₃ , MgTi ₂ O ₅ , MgTaO
_{It is} preferable to deposit a composite oxide such as ₆ , Mg ₄ GeO ₆ , Mg ₂ GeO _4, because the change of the precipitate during use is reduced.

[0018] Tabular grains are formed by thermal spraying.
gO component and mainly W, Ti, B, Ta, Te, Ge,
This is a method in which a compound composed of at least one element of V and Mo is dispersed, and ceramic powder and MgO constituting a matrix are mainly mixed with W, Ti, B and T.
Compounds composed of at least one element of a, Te, Ge, V, and Mo may be individually weighed, and then mixed powder may be prepared and coated. Alternatively, a plurality of thermal spraying guns may be used to coat each powder. Powder may be sprayed. Moreover, after at least two or more of these three types of powders are uniformly mixed, they may be mixed with the remaining powders and coated by thermal spraying.

Further, it is desirable that the deposited particles are dispersed in a portion of the ceramic layer where cracks develop, or that the density of the deposited particles in this portion is increased. That is, 0.1 to 300 μm near the metal member interface, and more preferably 0.1 to 300 μm.
It is desirable to increase the density of the precipitated particles at the site of 250 μm.

On the other hand, when the MgO composite oxide is dispersed in the vicinity of the outer surface of the ceramic layer, micro-cracks are generated due to a change in volume when a chemical reaction occurs, and the stress relaxation of the ceramic layer is increased. it can. Therefore, it may be dispersed not only in the vicinity of the metal bond layer but also on the outer surface.

At this time, the type of the composite oxide to be dispersed is not particularly specified, but the particles dispersed in the vicinity of the metal bond layer and on the outer surface may have the same composition or different compositions. . In particular, when the ceramic layer has a temperature gradient such as a thermal barrier coating layer, a high-melting composite oxide is placed near the outer surface of the high-temperature part, and a low-melting composite oxide is placed near the interface of the metal bond layer in the low-temperature part. The composite oxide may be dispersed.

The ceramic layer constituting the matrix is made of ZrO ₂ or CeO ₂ having a large coefficient of thermal expansion in order to reduce the thermal stress caused by the difference in coefficient of thermal expansion with the metal member.
Rare earth oxides such as ₂ are desirable. Particularly, ZrO ₂ is partially stabilized zirconia or stabilized zirconia mainly composed of tetragonal or cubic by adding a rare earth oxide or an alkaline earth oxide in order to suppress a phase transition caused by a thermal history. And good. On the other hand 1-30%
If monoclinic zirconia is distributed inside the coating layer, minute cracks can be formed in the layer, which is desirable from the viewpoint of thermal stress relaxation. Further, as a means for adding MgO, MgO may be added in the form of Mg-stabilized zirconia or stabilized zirconia whose crystal structure is stabilized by a rare earth element such as Mg and Y. In particular, when added in the form of Mg-stabilized zirconia, monoclinic zirconia is generated when Mg is separated in the heat treatment process, which is desirable from the viewpoint of thermal stress relaxation.

The structure of the ceramic layer constituting the matrix depends on the use of the heat-resistant member to be used.
Coat from 0 to 500 μm. Although the structure of the ceramic layer is not particularly limited, when coating under a single thermal spray condition (for example, raw material powder), it is preferable that the ceramic layer is coated so as to be laminated with a large surface roughness. The surface roughness immediately after coating is as low as 5
The thickness is preferably 0 μm or more, more preferably 52 μm or more. Further, when the coating layer has a Vickers hardness of 650 HV (load: 200 gf, 30 seconds) or less, a coating layer having excellent thermal stress relaxation properties can be produced. When a coating layer having a large surface roughness or a small hardness is formed in this manner, a coating layer having excellent thermal stress relaxation can be formed, and thus the peeling of the ceramic layer can be suppressed, and the coating layer can be formed. Life can be extended.

When the ceramic layer is coated under a plurality of thermal spraying conditions, it is desirable to coat the surface of the metal member with a small surface roughness from the surface to 200 μm, and it is more preferable that the surface roughness immediately after the coating is 50 μm or less. Is 48μ
m or less. The coating layer hardness was 650 HV (load 200 gf, 30 Vickers hardness).
When the time is not less than (seconds), it is desirable to suppress the generation of cracks because a coating layer having excellent thermal stress relaxation property can be produced and the peeling life of the coating layer can be improved.

When the ceramic layer needs to have a thickness of 200 μm or more, it is preferable to laminate a coating layer having a large surface roughness on the remaining portion. The surface roughness at that time is preferably Rz 50 μm or more, more preferably 52 μm or more.

By forming a multilayered structure in this way, a coating layer having a small surface roughness and a high hardness is provided in the vicinity of the metal member, and the remaining portion is formed of a coating layer having excellent thermal stress relieving properties. It is desirable because generation can be suppressed and peel resistance can be improved.

The MCrAlY alloy layer and the ceramic layer may be formed by an EB-PVD method, a magnetron sputtering method,
It can also be formed by a film forming method such as a CVD method.

[0028]

Next, specific examples of the present invention will be described. Example 1 A NiCoCrAlY layer having a thickness of about 150 μm was formed on the surface of a round bar made of a Ni-base super heat-resistant alloy CM-247 by plasma spraying, and then further coated with 8 wt% Y ₂ O ₃ stabilized ZrO ₂ .
A ceramic layer having a thickness of 250 μm was prepared using a powder in which 5 wt% MgO and 8.5 wt% WO ₃ were mixed, and used as a sample. The sample was then subjected to a preliminary heat treatment at 1073K for 2 hours and subsequently at 1273K for 16 hours. After the heat treatment, the ceramics layer was examined by X-ray diffraction. When the ceramics layer was composed mainly of Y-stabilized zirconia and MgWO ₄ , and further observed by SEM, flat particles composed of MgWO ₄ were dispersed inside the ceramics layer. I was

Example 2 The surface of a round bar made of a Ni-base super heat-resistant alloy CMSX-2 was
A 0 μm NiCoCrAlY layer is formed, and then
1.5 wt% MgO in advance to wt% Y ₂ O ₃ stabilized ZrO ₂
7. Melt pulverized powder and WO3 powder prepared by adding t%
Using a powder mixed with 5 wt% as a thermal spraying raw material powder, 25
0 μm was prepared and used as a sample. Next, the sample was
Heat treatment was performed at K for 3 hours and subsequently at 1273K for 16 hours. The ceramic layer after the heat treatment is 8 wt% Y ₂ O
_In addition to the stabilized ZrO ₂ , tabular grains of MgWO ₄ were dispersed between the sprayed zirconia grains.

Comparative Example 1 A surface of a round bar made of a Ni-base super heat-resistant alloy CMSX-2 was
A 0 μm NiCoCrAlY layer is formed, and then
Using only wt% Y ₂ O ₃ -stabilized ZrO ₂ as a raw material powder, a 250 μm sample was prepared and used as a sample. Next, the sample is
Heat treatment was performed at 1073K for 3 hours and subsequently at 1273K for 16 hours. The ceramic layer after heat treatment is 8wt
In addition to the% YO ₃ stabilized ZrO ₂ , MgO was dispersed between the zirconia spray particles.

In this sample, in an atmosphere at 1123 K, which simulates an atmosphere to which members are exposed during operation of the gas turbine,
When a repeated heating test was performed at room temperature with a stress of 250 MPa and a cycle of 12 hours at a room temperature, peeling did not occur even when the cycle exceeded 1000 cycles. After the test, when the cross section of the sample was observed, it was found that 8 wt% Y ₂ O ₃ stabilized ZrO ₂
Some cracks were found inside the layer,
It was found that the crack growth was suppressed by needle-like or tabular grains. (Examples 1 and 2) In Comparative Example 1 of the present invention, no precipitation phase (acicular or tabular grains) was observed inside the ceramic layer after the heat treatment, and peeling of the zirconia layer started in 700 cycles, and
It completely peeled off in 00 cycles.

Example 3 The surface of a round bar made of a Ni-base super heat-resistant alloy CMSX-2 was
A 0 μm NiCoCrAlY layer is formed, and then
wt% Y ₂ O ₃ stabilized ZrO ₂ and 8mass% MgO stabilized zirconia 10: 2 WO to the mixed powder at a ratio of
_Four powders mixed at 17 mass% were used as the raw material powder for thermal spraying to produce a 200 μm sample. The sample was then incubated at 1073K for 3 hours followed by 1273K for 1 hour.
Heat treatment was performed for 6 hours. The ceramic layer after heat treatment
In addition to 8 wt% Y ₂ O ₃ stabilized ZrO ₂ and monoclinic zirconia, MgWO ₄ of tabular grains was dispersed between the sprayed zirconia grains.

Comparative Example 2 A round bar made of a Ni-base superalloy CMSX-2 was
A 0 μm NiCoCrAlY layer is formed, and then
A 200 μm powder was prepared by using a powder obtained by mixing wt% Y ₂ O ₃ stabilized ZrO ₂ and 8 wt% MgO stabilized zirconia at a ratio of 10: 2 as a thermal spraying raw material powder to prepare a sample. The sample was then subjected to 1073K for 3 hours followed by 1273K.
For 16 hours. In the ceramic layer after the heat treatment, 8 wt% Y ₂ O ₃ stabilized ZrO ₂ and monoclinic zirconia were formed.

In this sample, in an atmosphere at 1123 K, which simulates an atmosphere to which members are exposed during operation of the gas turbine,
When a repeated heating test was performed at room temperature with a stress of 250 MPa and a cycle of 12 hours at room temperature, peeling did not occur even when the cycle exceeded 1000 cycles. After the test, when the cross section of the sample was observed, a portion where a crack was slightly grown inside the 8 wt% Y ₂ O ₃ stabilized ZrO ₂ layer was also found, but the crack growth was suppressed by needle-like or tabular grains. I knew it was. (Example 3) In Comparative Example 2 of the present invention, no precipitated phase (acicular or tabular grains) was observed inside the ceramic layer after the heat treatment, and the ceramic layer was separated by a short heat cycle.

[0035]

As described above, according to the heat-resistant member of the present invention, needle-like or flat particles are dispersed inside the ceramic layer to prevent the ceramic layer from peeling off, and to improve the reliability and life of the heat-resistant member. Can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal base material 2 ... MCrAlY alloy layer 3 ... Ceramics layer 4 ... Dispersed particles

Continued on the front page (72) Inventor Hiroki Inagaki 1 Tokoba, Komukai Toshiba-cho, Saisaki-ku, Kawasaki-shi, Kanagawa

Claims (4)

[Claims] 1. A substrate made of an alloy containing at least one element selected from Ni, Co and Fe as a main component,
A heat-resistant member comprising: a ceramic layer formed on the surface of the base material and having tabular grains dispersed on the MCrAlY alloy layer. 2. The heat-resistant member according to claim 1, wherein the tabular grains are a composite oxide containing Mg. 3. The ceramic layer comprises a rare earth oxide,
The heat-resistant member according to claim 1, wherein the heat-resistant member is at least one selected from stabilized zirconia and partially stabilized zirconia stabilized with an alkaline earth metal oxide. 4. It has an MCrAlY alloy layer (M is at least one element selected from Ni, Co and Fe),
A ceramic layer is formed on a substrate surface made of an alloy containing at least one element selected from Ni, Fe and Fe as a main component by using a ceramic raw material powder containing Mg and an element which reacts with Mg to form a composite oxide. And a step of heating so as to form tabular particles made of a composite oxide containing Mg in the ceramic layer.