JPH07258817A - Heat resistant member - Google Patents

Abstract

PURPOSE:To produce a heat resistant member having a heat resistant coating layer formed via a binding layer to the surface of a metal as a base material. CONSTITUTION:This member is a heat resistant member which has a layer 3, formed via a binding layer 2 on the surface of a metallic base material 1 and composed essentially of partially stabilized zirconium oxide, and a layer 4 composed essentially of aluminum oxide and formed on the surface of the layer composed essentially of partially stabilized zirconium oxide. By this method, this member has a heat resistant coating layer excellent in steam corrosion resistance and high temp. erosion resistance as well as in thermal insulation effect even under high temp. conditions and also a remarkable effect of having superior durability at high temp. can be provided.

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 obtained by coating a metal base material with a ceramic heat resistant coating, and more particularly to a heat resistant member having improved high temperature durability.

[0002]

2. Description of the Related Art Conventionally, a member made of a heat-resistant alloy has been used as a member that is required to have heat resistance such as a member that constitutes a gas turbine, but in recent years, the required heat-resistant temperature has been increased. For example, in the case of gas turbine components,
Since the gas temperature in the gas turbine reaches 1400 ° C. or higher, there is a need for a high temperature heat resistant member that can withstand the harsh conditions of use.

As a result of various studies on heat resistant members having excellent heat resistance, (1) heat resistant ceramic materials having low thermal conductivity such as silicon nitride (Si ₃ N ₄ ) and silicon carbide instead of heat resistant alloys. Method of using as a heat-resistant member, (2)
A method of using a heat-resistant alloy member having a cooling mechanism, such as using the heat-resistant alloy member in a hollow shape and cooling the member by circulating a cooling gas, and (3) the heat-resistant alloy substrate surface Techniques such as a method of applying a heat resistant coating made of ceramic to protect the base alloy from high heat have been proposed.

However, in the case of the above method (1),
Since the strength of the material does not reach that of alloy members, it has not yet been put to practical use. Further, in the case of the method (2), there is a problem that the thermal efficiency of the entire system decreases as the member is cooled. After all, the method (3) is currently regarded as the most promising from the viewpoints of strength and thermal efficiency.

However, since the coefficient of thermal expansion of ceramics is generally smaller than that of metals, when a heat resistant member obtained by applying a ceramic heat resistant coating to a heat resistant alloy base material is used under high temperature conditions, the thermal expansion of the base metal and the ceramic coating is performed. Due to the difference, peeling of the ceramic layer is likely to occur. Therefore, it is desired that the ceramic applied to the heat resistant coating has not only a low thermal conductivity but also a thermal expansion coefficient close to that of the heat resistant alloy.

From this point of view, it is preferable to use partially stabilized zirconium oxide (ZrO ₂ .Y ₂ O ₃ ) as a heat-resistant coating because of its low thermal conductivity, and among the ceramics, the coefficient of thermal expansion is relatively close to that of a heat-resistant alloy. Thermal Spray Handbook "P.
516 (edit: Japan Thermal Spray Association, published by: New Technology Development Center Co., Ltd.).

However, the partially stabilized zirconium oxide (ZrO ₂ .Y ₂ O ₃ ) has an insufficient heat-shielding effect as the temperature rises, and has low wear resistance and poor high-temperature erosion resistance. Further, there is a problem that corrosion is likely to occur when used in a steam atmosphere.

[0008]

The object of the present invention is to eliminate the above-mentioned drawbacks of the conventional heat-resistant member, and is excellent in the heat-shielding effect even under high temperature conditions, and is resistant to steam corrosion.
Another object of the present invention is to provide a heat-resistant member having a high-temperature durability that has a heat-resistant coating layer that is also excellent in high-temperature erosion resistance.

[0009]

SUMMARY OF THE INVENTION The present invention comprises a metal substrate,
A heat-resistant member having a heat-resistant coating layer provided on the surface of the metal substrate via a bonding layer, wherein the heat-resistant coating layer comprises partially stabilized zirconium oxide provided on the surface of the metal substrate via the bonding layer. A heat-resistant member comprising a layer mainly composed of a layer and a layer mainly composed of aluminum oxide provided on a surface of the layer mainly composed of partially stabilized zirconium oxide.

The present invention will be described in detail below. First, as the metal base material according to the present invention, various heat-resistant alloys can be appropriately selected and used according to the application.
An i-base superalloy and a Co-base superalloy are preferable because of their high strength. Ni
As the base alloy, specifically, the composition is Cr: 12 to 20% by weight to 20% by weight, Co: 5 to 10% by weight, Mo: 1 to 1%.
3% by weight, W: 2 to 6% by weight, Ta: 1 to 3% by weight, A
1: 2-5% by weight, Ti: 2-5% by weight, Ni: balance,
IN738, IN738LC, IN939, MAR-
Examples include alloys such as M247.

Further, as the Co-based superalloy, specifically, the composition is Ni: 5 to 15% by weight, Cr: 25 to 35% by weight, W: 5 to 10% by weight, Fe: 0.5 to 3% by weight. %, C
o: Co-based alloys such as the balance FSX-414 are also preferable because of their high strength. Specifically, X-40, MAR-M50
9, alloy such as FSX-414.

Further, the heat-resistant member according to the present invention has a heat-resistant coating layer on the surface of the metal base material via a bonding layer. The tie layer is 1. 1. To improve the high temperature corrosion resistance of metal substrates It has an effect of relaxing the thermal stress generated due to the difference in thermal expansion between the metal base material and the heat resistant coating layer.

Examples of the bonding layer include Ni-based MCrAlY alloys and Co-based MCrAlY alloys having excellent characteristics 1 and 2 above. Specifically, as the Ni-based MCrAlY alloy, for example, Co: 10 to 40 wt%, Cr: 10 to 40
Alloy having a composition of wt%, Al: 5 to 20 wt%, Y: 0.1 to 3 wt%, Ni: balance, or A
1: 5 to 30% by weight, Y: 0.1 to 5.0% by weight, N
An alloy having a composition of i: balance is included. Also, C
As the o-based MCrAlY alloy, for example, Cr: 10-
40% by weight, Al: 5 to 20% by weight, Y: 0.1 to 3% by weight, Co: alloy having the composition of the balance, or A
1: 5 to 30% by weight, Y: 0.1 to 5.0% by weight, C
Examples include alloys having a composition of o: balance.

The thickness of the bonding layer is 50 μm or more and 300 μm
The following is desirable. If the thickness of the binding layer is too small, the effect of relaxing the thermal stress generated between the base material and the heat resistant coating layer will be reduced, and the binding force will be reduced, and if it is too thick, the performance as a binding layer will not be improved.

The heat resistant coating layer according to the present invention is
(A) A layer mainly composed of partially stabilized zirconium oxide provided on the surface of the base metal via a bonding layer (hereinafter, referred to as “A layer”).
And ) And (b) a layer containing aluminum oxide as a main component (hereinafter referred to as “B layer”) provided on the surface of the layer containing mainly partially stabilized zirconium oxide.

The layer A is a partially stabilized zirconium oxide (ZrO ₂ .Y ₂ O ₃ ) stabilized with yttrium oxide.
Mainly. This partially stabilized zirconium oxide is
The solid solution amount of ₂ O ₃ is preferably 4% by weight to 20% by weight. Within this range, the stabilizing effect is strong and the amount of steam corrosion is small. Further, it is desirable that Y ₂ O ₃ be solid-solved in the range of 6% by weight to 12% by weight. Further, the partially stabilized zirconium oxide is MgO, CaO, CeO ₂ ,
It is preferable that at least one compound selected from the group of Yb ₂ O ₃ , Sc ₂ O ₃ , In ₂ O ₃ and Nd ₂ O ₃ is solid-solved, because the mechanical strength is improved. It is preferable that the solid solution compound has a solid solution amount of 0.05% by weight or more and 5.0% by weight or less.

In the present invention, the thickness of layer A is 100.
It is preferably at least μm and at most 500 μm. 10
If it is less than 0 μm, the heat effect is lowered and the high temperature durability is lowered. When it exceeds 500 μm, the adhesive strength of the coating layer is lowered, and peeling easily occurs.

The B layer is made of aluminum oxide (Al ₂
Mainly O ₃ ). The thickness of layer B is 50 μm or more, 30
It is preferably 0 μm or less. If it is less than 50 μm, the heat-shielding effect, high temperature erosion resistance and steam corrosion prevention effect tend to be reduced, and if it exceeds 300 μm, the adhesive strength of the coating layer tends to be low and peeling tends to occur easily.

A graded composition may be used in which the content of aluminum oxide is gradually increased from the amount of partially stabilized zirconium oxide from the layer A to the layer B at the boundary between the layers A and B. Thereby, the adhesive strength between the A layer and the B layer can be improved and the thermal shock resistance can be improved. When the boundary between the A layer and the B layer has a graded composition of partially stabilized zirconium oxide and aluminum oxide, the thickness of the A layer is 100 μm.
Or more and 500 μm or less, and the thickness of the B layer is 50 μm or more and 300
It is desirable that the thickness is less than or equal to μm, and the thickness of the boundary portion is greater than or equal to 50 μm and less than or equal to 200 μm. If the thickness of the boundary portion is too thick, the thickness of the entire heat resistant coating layer becomes large and peeling easily occurs, while if it is too thin, the effect of improving the adhesive strength becomes weak.

In the heat resistant member of the present invention, the bonding layer, the A layer, and the B layer are sequentially formed on the surface of the base metal having a desired shape by the thermal spraying method and the CVD method.
It can be obtained by forming by a method such as a PVD method or a PVD method. In the case of applying the thermal spraying method, if the base metal surface is subjected to sandblasting using Al ₂ O ₃ particles or the like before forming the bonding layer, the base metal surface becomes rough and a state suitable for forming the coating layer is obtained. Therefore, it is preferable.

The formation of the bonding layer is particularly preferably carried out by the plasma spraying method, because the coating layer is densified, the high temperature erosion resistance is improved, and the forming speed is high. Further, when the outermost surface of the coating layer of the finally obtained heat-resistant member is remelted and solidified by laser, the coating layer surface is densified and smoothed, and further steam corrosion resistance and high temperature erosion resistance can be improved. it can.

[0022]

In the present invention, the heat resistant coating layer provided on the surface of the metal base material via the bonding layer is mainly composed of (a) partially stabilized zirconium oxide provided on the metal surface of the base material via the bonding layer. A layer (A layer); and (b) a layer mainly containing aluminum oxide (B layer) provided on the surface of the layer mainly containing partially stabilized zirconium oxide. Thereby, the high temperature durability of the member can be made excellent.

That is, by providing a layer mainly containing aluminum oxide (Al ₂ O ₃ ) having a high thermal emissivity and a high thermal reflectance on the surface of the A layer, the heat-shielding property of the heat resistant coating layer can be improved. . In addition, aluminum oxide (Al
_The layer mainly composed of ₂ O ₃ ) has good high temperature erosion resistance and steam corrosion resistance, and by applying aluminum oxide (Al ₂ O ₃ ) as the outermost surface layer, the high temperature erosion resistance of the heat resistant member can be improved. And the steam corrosion resistance can be improved. Further, regarding the coefficient of thermal expansion of the material forming the bonding layer and the heat-resistant coating layer according to the present invention, the coefficient of thermal expansion gradually decreases in the order of bonding layer-A layer-B layer. Even if there is, peeling of the coating layer due to the difference in thermal expansion of the material forming the coating layer is less likely to occur.

[0024]

【Example】

(Example 1, Comparative Example 1, Comparative Example 2) FIG. 1 is a cross-sectional perspective view of a heat-resistant member according to this Example. In FIG. 1, 1 is a base material. The base material 1 is IN738LC (composition 16Cr-
8.5Co-2.6W-1.7Mo-3.4Ti-1.
It is a pipe made of Ni-based alloy composed of 7Ta-the balance Ni).

First, the surface of the substrate 1 was sandblasted using Al ₂ O ₃ particles to roughen it. Next, the bonding layer 2 was formed on the surface of the base material 1 by plasma spraying to a thickness of 150 μm.
Formed with a thickness of. The composition of the bonding layer is Co: 24% by weight,
Cr: 16% by weight, Al: 12% by weight, Y: 0.5% by weight, Ni: balance.

Next, a heat resistant coating layer was formed. First, a partially stabilized zirconium oxide layer 3 having a thickness of 250 μm was formed on the surface of the bonding layer 2 by a plasma spraying method using a partially stabilized zirconium oxide powder having a composition of 8 wt% Y ₂ O ₃ and the balance ZrO ₂ . . Furthermore, using aluminum oxide powder,
An aluminum oxide layer 4 having a thickness of 100 μm was formed on the partially stabilized zirconium oxide layer 3 by plasma spraying.

The heat resistant member (pipe) shown in FIG. 1 was manufactured by the above procedure. Using the heat-resistant member thus obtained, a heat-shielding characteristic measurement test was conducted. In the test, the surface of the pipe was heated to 1100 ° C., a thermocouple was installed on the inner surface of the pipe, and the temperature of the inner surface of the pipe was measured while cooling the air by flowing 25 liters of air per minute into the pipe. The temperature of the inner surface of the pipe of this example was 795 ° C.

As Comparative Example 1, a heat-resistant member similar to that of Example 1 was prepared except that the aluminum oxide layer 4 was not applied to the outermost surface. When the heat-shielding characteristics of the heat-resistant member of this comparative example were measured in the same manner as in the example, the pipe inner surface temperature was 825 ° C.

As Comparative Example 2, the heat-shielding property was measured in the same manner as in Example 1 with respect to the pipe made of the Ni-based alloy used as the substrate 1 in Example 1 in which the bonding layer 2 and the heat-resistant coating layer were not applied. The pipe inner surface temperature was 910 ° C.

From the above results, it is clear that the heat-resistant member provided with the heat-resistant coating according to the present invention has excellent heat-shielding properties. (Example 2 and Comparative Example 3) FIG. 2 is a sectional view of a heat-resistant member according to this example. In FIG. 2, 1 is a base material. Substrate 1
Is 50mm x 50mm x 5m made of IN738LC
It is a member made of Ni-based alloy of m (thickness).

First, the surface of the substrate 1 was sandblasted using Al ₂ O ₃ particles to roughen it. Next, the bonding layer 2 was formed on the surface of the base material 1 by plasma spraying to a thickness of 150 μm.
Formed with a thickness of. The composition of the bonding layer is Co: 24% by weight,
Cr: 16% by weight, Al: 12% by weight, Y: 0.5% by weight, Ni: balance.

Next, a heat resistant coating layer was formed. First, a partially stabilized zirconium oxide layer 3 having a thickness of 250 μm was formed on the surface of the bonding layer 2 by a plasma spraying method using a partially stabilized zirconium oxide powder having a composition of 8 wt% Y ₂ O ₃ and the balance ZrO ₂ . . Furthermore, using aluminum oxide powder,
An aluminum oxide layer 4 having a thickness of 150 μm was formed on the partially stabilized zirconium oxide layer 3 by plasma spraying.

The heat resistant member shown in FIG. 2 was manufactured by the above procedure. A high temperature erosion test was performed using the obtained heat resistant member. The test heats the heat resistant member to 900 ° C,
Al ₂ O ₃ particles having a diameter of about 10 μm were applied to the heat-resistant coating layer at a pressure of 4
As a result of collision for 1 hour under the condition of atmospheric pressure and flow velocity of 10 m / s,
The reduction amount of the member was 2 mg / cm ² .

A steam corrosion test was conducted using the heat-resistant member of this example. For the test, an autoclave tester was used, and after the heat resistant member was installed in the tester, the member was exposed to water vapor at 200 ° C. and 15 atm. As a result of observing the surface and the cross section of the heat resistant coating layer of this test piece with a microscope, steam corrosion was not observed.

As Comparative Example 3, a heat-resistant member similar to that of Example 2 was prepared except that the aluminum oxide layer 4 was not applied to the outermost surface. When the high temperature erosion test was performed on the heat resistant member of this comparative example in the same manner as in the example, the reduction amount of the member was 3.2 mg / cm ² .

A steam corrosion test was conducted using the heat resistant member of Comparative Example 3. For the test, an autoclave tester was used, and after the heat resistant member was installed in the tester, the member was exposed to water vapor at 200 ° C. and 15 atm. As a result of observing the surface and cross section of the heat-resistant coating layer of this test piece with a microscope, it was a structure in which many cracks were generated due to steam corrosion.

From the above results, it is clear that the heat resistant member provided with the heat resistant coating according to the present invention is excellent in erosion resistance and steam corrosion resistance. (Example 3) The same substrate as that used in Example 2 was prepared. Next, a bonding layer having a thickness of 150 μm was formed on the surface of the base material by the plasma spraying method. The composition of the bonding layer is Co: 2
4% by weight, Cr: 16% by weight, Al: 12% by weight, Y:
0.5% by weight, Ni: balance. Next, a heat resistant coating layer was formed. First, a partially stabilized zirconium oxide powder having a composition of 8 wt% Y ₂ O ₃ and the balance ZrO ₂ was used to form a partially stabilized zirconium oxide layer having a thickness of 200 μm on the surface of the bonding layer by plasma spraying. Next, an aluminum oxide layer was formed on the surface of the partially stabilized zirconium oxide layer by a plasma spraying method using aluminum oxide powder as the thermal spraying powder. At that time, thermal spraying was performed while adjusting the composition of the thermal spraying powder to partially stabilize the powder. At the boundary between the zirconium oxide layer and the aluminum oxide layer, a layer having a graded composition in which the aluminum oxide content is gradually increased from the partially stabilized zirconium layer toward the aluminum oxide layer is provided. About 100 μm was formed. The thickness of the sprayed layer of aluminum oxide alone on the outermost surface was 100 μm.

The heat resistant member shown in FIG. 2 was manufactured by the above procedure. A thermal shock test was performed using the obtained heat resistant member. In the thermal shock test, the heat resistant member was kept at 1100 ° C for 30 minutes.
Retaining for 30 minutes at room temperature was repeated and the number of times until peeling of the heat resistant coating layer was measured. The heat-resistant member of Example 3 is 3000
Peeling did not occur even after repeated times.

On the other hand, when the heat-resistant member of Example 2 was similarly subjected to the thermal shock test, peeling was recognized after 2650 times. Therefore, it is understood that the thermal shock resistance is improved by providing the layer having the gradient composition at the boundary between the partially stabilized zirconium oxide layer and the aluminum oxide layer.

[0040]

INDUSTRIAL APPLICABILITY As described above, the heat-resistant member of the present invention has excellent heat-shielding effect even under high-temperature conditions, excellent steam corrosion resistance, and excellent high-temperature durability with a heat-resistant coating layer having excellent high-temperature erosion resistance. Has a remarkable effect.

[Brief description of drawings]

FIG. 1 is a sectional perspective view of a heat-resistant member according to a first embodiment.

FIG. 2 is a cross-sectional view of a heat resistant member according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Bonding layer 3 ... Partially stabilized zirconium oxide layer 4 ... Aluminum oxide layer

Claims (2)

[Claims] 1. A heat resistant member comprising a metal base material and a heat resistant coating layer provided on the surface of the base metal via a bonding layer, wherein the heat resistant coating layer is bonded to the surface of the metal base material via the bonding layer. A heat-resistant member, comprising: a layer mainly composed of partially stabilized zirconium oxide and a layer mainly composed of aluminum oxide provided on the surface of the layer mainly composed of partially stabilized zirconium oxide. 2. The heat resistant member according to claim 1, wherein a boundary portion between the partially stabilized zirconium layer and the aluminum oxide layer of the heat resistant coating layer has a gradient composition of partially stabilized zirconium oxide and aluminum oxide.