JPH0920976A - Material resistant to corrosion and oxidation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material resistant to corrosion and oxidation, applicable to the moving blade and stationary blade of a gas turbine or the burner high- temp. parts of a boiler, having the resistance to oxidation and corrosion equivalent to or higher than the conventional material having an Al cementation layer and capable of being easily produced. SOLUTION: The metallic layer of MCrAlY (M consists essentially of one or >=2 kinds of elements among Ni, Co and Fe) is formed on the surface of a base material directly or by low-pressure plasma spraying, and then the metallic layer of a CoAl single-phase alloy contg. 44-56 atomic % Al or of an FeAl single-phase alloy contg. 34-48 atomic % Al is formed by low-pressure plasma spraying to constitute the material resistant to corrosion and oxidation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the operation of a gas turbine.
Corrosion resistance applied to high temperature components such as vanes and burner high temperature of boiler
It relates to oxidation resistant materials.

[0002]

2. Description of the Related Art A conventional corrosion-resistant and oxidation-resistant material for a gas turbine moving / stator blade has a structure as shown in FIGS. That is, it has a structure in which the metal layer A is formed on the surface of the base material 1 or a structure in which the metal layer A is formed on the surface of the base material 1 and further the metal layer C is formed thereon.
The metal layer A designated by the reference numeral 2 in FIG. 3 is generally MCr.
A coating film having a composition consisting of AlY (M: any one of Ni, Co, and Fe, or two kinds of elements), which is rich in corrosion resistance and oxidation resistance, and in consideration of phase stability with the base material 1. And is constructed by the low pressure plasma spraying method. In the material of FIG. 4, in order to improve the corrosion resistance and the oxidation resistance of the coating film of the material of FIG. 3, a metal layer C, which is an Al diffusion permeation treatment layer indicated by reference numeral 4, is further applied on the metal layer A. There is.

[0003]

In recent years, the gas inlet temperature of the turbine has been increasing to improve the efficiency of the gas turbine, and on the other hand, there is a tendency to use poor fuel for better economy. In addition, corrosive components from the atmosphere as intake air peculiar to the gas turbine are mixed. Due to these factors, that is, high temperature, poor fuel, and the inclusion of corrosive components from the atmosphere, high temperature corrosion and oxidation of moving and stationary blades are becoming more severe.

Therefore, a coating film having more excellent corrosion resistance and oxidation resistance is required, and the above-mentioned coating films shown in FIGS. 3 and 4 are currently used. In the material shown in FIG. 3, alloy powder (metal layer A) having a composition of MCrAlY (M: any one element of Ni, Co and Fe or two elements) is used for low pressure plasma spraying. Coating the base material of Ni-based or Co-based superalloy (IN738LC etc.) used for moving and stationary blades.
The composition of MCrAlY is phase stable with the base material (MCrAlY
(It is difficult to form a brittle intermetallic compound on the boundary between the base metal and the base metal and the base metal side), etc., the Cr content is about 30% or less,
Since the amount of Al is suppressed to about 15% or less, its corrosion resistance and oxidation resistance are not sufficient. On the other hand, in the material shown in FIG. 4, an Al diffusion and permeation treatment layer (metal layer C) is applied on the metal layer A for further improvement in corrosion resistance and oxidation resistance, and the corrosion resistance Although it has excellent oxidation resistance, the cost is high due to the complicated work process.

The present invention manufactures a coating film which is superior in corrosion resistance and oxidation resistance to the above-mentioned conventional coating film of MCrAlY only, and is cheaper than a coating film of MCrAlY coated with an Al diffusion permeation treatment layer. An object of the present invention is to provide a corrosion-resistant / oxidation-resistant material having a coating film having excellent corrosion resistance / oxidation resistance.

[0006]

According to the present invention, (1) 44 to 56 atomic% of Al is formed on the surface of a base material by a low pressure plasma spraying method.
, A corrosion-resistant and oxidation-resistant material, characterized in that a metal layer of a CoAl single-phase alloy containing Al or a FeAl single-phase alloy containing 34 to 48 atomic% Al is formed, (2) low-pressure plasma on the surface of the base material. MCrAlY (M: Ni, Co,
CoAl single-phase alloy in which a metal layer of any one element of Fe (mainly consisting of one element or two elements) is formed, and 44 to 56 atomic% of Al is further formed on the surface thereof by low pressure plasma spraying. Or F containing 34 to 48 atomic% of Al
It is a corrosion-resistant and oxidation-resistant material characterized by forming a metal layer of an eAl single-phase alloy.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the first aspect of the present invention, a CoAl single phase alloy or 3 containing 44 to 56 atomic% of Al directly on a base material.
A coating film of a metal layer B of a FeAl single phase alloy containing 4 to 48 atomic% of Al is formed. In order to improve the adhesion and uniformity between the coating layer and the base material, heat treatment is performed after the material also serves as the base material recovery.

According to the second aspect of the present invention, the conventional MCrAlY (M: Ni, C) is formed on the surface in contact with the base material.
o, a CoAl single-phase alloy containing a metal layer A which is a coating film of any one element of Fe and two elements) and which contains 44 to 56 atomic% of Al, or 34 to 48 A coating film of a metal layer B of a FeAl single-phase alloy containing atomic% Al is formed. In order to improve the adhesion and uniformity between the coating layer and the base material, heat treatment is performed after the material also serves as the base material recovery. In the metal layer B containing a high concentration of Al, a dense Al ₂ O ₃ film is easily formed by contact with oxygen, and excellent corrosion resistance and oxidation resistance are obtained.

In the corrosion-resistant and oxidation-resistant material of the present invention, Co
A Ni-base superalloy (IN738LC, Udimet) is used as a base material for directly forming an Al single phase alloy or a FeAl single phase alloy.
520, IN939, etc.) or Co-based superalloy (EC)
(Y738, X-45, etc.) are preferable. In the middle, M
When forming a metal layer of CrAlY, MCrAl
Any material capable of forming a Y film can be used without any trouble.

Further, even when two layers of the metal layers A and B are formed, the coating method of the metal layer B is the same low-pressure plasma spraying method as that of the metal layer A, and therefore the coating of the metal layer A is performed subsequently. Therefore, the coating film can be made uniform and the adhesion with the base material can be improved. Further, a post-heat treatment (maintaining at about 800 to 1200 ° C. for several hours to 30 hours) can be continuously performed, so that the process is remarkably simplified and shortened as compared with the Al diffusion permeation treatment method.

The Al content in the metal layer B is 44 to 56 atom% in the case of CoAl alloy and 34 in the case of FeAl alloy.
It is C within this composition range that is specified in the range of up to 48 atom%.
This is because a single phase alloy of oAl and FeAl can be obtained.
If the Al content is higher than this, CoAl + Al or F
It becomes a two-phase alloy of eAl + Al. Conversely, when the content of Al is small, it becomes a two-phase alloy of CoAl + Co or FeAl + Fe. In the case of such a two-phase alloy, there arises a problem in structural stability at high temperature. Further, when the Al content is low, the ductility is increased, which is advantageous in terms of workability, but when considering the oxidation resistance, the higher the Al content, the better. Therefore, the above range is preferable also from these points.

[0012]

The present invention will be described more specifically with reference to the following examples. (Example 1) Co on the surface of a cylindrical base material (material IN738LC Ni-based alloy) having a diameter of 10 mm and a length of 50 mm, Co
A metal layer B or a metal layer A + B made of an Al alloy is formed, and a test piece of the material of the present invention having the configuration of FIG.
o. 1-4) were prepared. A powder having a composition shown in Table 1 (particle size: 150 μm or less) was used as a raw material, and a coating film having a thickness shown in Table 1 was formed by a low pressure plasma spraying method (LPPS) under the spraying conditions shown in Table 5. The chemical composition of the metal layer A (MCrAlY: CoNiCrAlY in this example) is 31 to 33Ni-20 to 22Cr-7 to 9A.
1-0.25 to 0.65Y-remaining Co (% by weight). After that, the temperature is maintained at 1120 ° C. ± 15 ° C. for 2 hours, once cooled with nitrogen gas, again heated to 843 ° C. ± 15 ° C., and held for 24 hours, and then cooled with nitrogen gas to perform a post heat treatment, thereby performing a post-heat treatment. A test piece having the required material strength was obtained while ensuring adhesion and uniformity with the base material. In this test, the treatment was performed at 1120 ° C. ± 15 ° C. × 2 hours and 843 ° C. ± 15 ° C. × 24 hours, but the former may be omitted if the base material does not require solution heat treatment.

Sample No. of the comparative material shown in Table 1 No. 6 is the sample No. It was produced in the same manner as the materials of the present invention 1 to 4. However, the metal layer B was not applied, and the metal layer A was used as shown in FIG.
Only. In addition, the sample No. of the comparative material. For 5,
After coating the metal layer A as described above, this test piece was mixed with Al powder and alumina and ammonium chloride (Al: 15% of particle size 0.5-2 mm, ammonium chloride: 1%, balance: particle size). 0.5-2 mm alumina)
It was embedded in a powder consisting of the above and was treated at 1100 ± 15 ° C. for 10 hours while flowing an ammonium chloride gas to perform Al diffusion permeation treatment. Then, in order to secure the material strength of the base material, 1120 ° C. ± 15 ° C. × 2 hr / nitrogen gas cooling, and then 843 ° C. ± 15 ° C. × 24 hr / nitrogen gas cooling were carried out, and a heat treatment was performed to obtain a test sample. Note that, after the Al diffusion / permeation treatment, the cooling rate from the Al diffusion / permeation treatment temperature is very slow, so it is necessary to recover the material. Therefore, the post heat treatment is essential.

[0014]

[Table 1]

Using the test piece prepared as described above, the temperature was 1100 ± 15 ° C. in an electric furnace in an air atmosphere at 10 ° C.
An oxidation test was performed by heating for 00 hours. The weight of the test piece after heating was measured, and the weight increase due to oxide formation was determined from the difference from that before heating. Then, the sample No. The weight increase amount of 6 was set to 1, and the ratio of the weight increase amount of each test piece to this was shown in Table 2. From the results in Table 2,
The material of the present invention is sample No. It can be seen that the oxidation resistance is remarkably superior to that of No. 6.

Next, a high temperature corrosion test was conducted using the above test piece. As a test method, corrosive ash (V
₂ O ₅ : Na ₂ SO ₄ = 80: 20, weight ratio) 20 m
It is applied to the entire surface of the test piece at a rate of g / cm ² and is 85 in the air.
It was heated at 0 ± 15 ° C. for 100 hours (corrosion ash was applied every 20 hours, and 5 cycles in total for 100 hours). After the test, the scale was washed with hot water and the weight was measured, and the weight loss was determined by the difference from that before the corrosion test. Then, the sample No.
The weight loss of No. 6 was set to 1, and the ratio of the weight loss of each test piece to this was shown in Table 2. From the results in Table 2, the material of the present invention is a comparative material, Sample No. It can be seen that the corrosion resistance is remarkably superior to that of No. 6. In particular, the sample No. No. 4 is sample No. 4. 5
It may be noted that it has the same corrosion resistance as that of the comparative material.

Sample No. The results of trial calculation of costs for applying the coatings 1 to 6 are shown in Table 2. In Nos. 1 to 4, sample No. of the comparative material. It was 1.5 to 1.7 times that of No. 6. This is a cost increase due to the high cost of the CoAl powder as a raw material, but there are still some things when the life extension of the product is taken into consideration due to the performance improvement. On the other hand, sample No. of the comparative material. In No. 5, the Al diffusion diffusion treatment is carried out, resulting in a significant increase in cost.

[0018]

[Table 2]

(Embodiment 2) A metal layer B or a metal layer A + B made of FeAl alloy is formed on the surface of the same cylindrical base material (material IN738LC Ni-based alloy) used in Embodiment 1.
Was formed to prepare test pieces (Material Nos. 7 to 10) of the material of the present invention having the configuration of FIG. 1 or 2. A powder having a composition shown in Table 3 (particle size: 150 μm or less) was used as a raw material, and a coating film having a thickness shown in Table 3 was formed by a low pressure plasma spraying method (LPPS) under the spraying conditions shown in Table 5.
The metal layer A (MCrAlY: CoNiC in this example)
The chemical composition of rAlY) is the same as in Example 1 and is 31 to 33N.
i-20 to 22Cr-7 to 9Al-0.25 to 0.65
Y-remaining Co (% by weight). Further, the subsequent heat treatment was performed in the same manner as in Example 1.

Sample No. of the comparative material shown in Table 3 No. 11 is the sample No. It was produced in the same manner as 7 to 10 materials of the present invention. However, the metal layer B was not applied and only the metal layer A was used as shown in FIG. In addition, the sample No. of the comparative material. For No. 12, after coating the metal layer A as described above, Al diffusion permeation treatment and post heat treatment were performed in the same manner as the comparative material 6 of Example 1 to obtain test samples.

[0021]

[Table 3]

Using the test piece prepared as described above, an oxidation test, a high temperature corrosion test and a trial calculation of the cost were carried out in the same manner as in Example 1. The results are shown in Table 4.

The results in Table 4 all show numerical values and trends that are almost the same as in Example 1. That is, all of the materials of the present invention are sample Nos. 12 has a significantly higher corrosion resistance than Sample No. 12, and especially Sample No. The materials of Nos. 7 and 10 are sample No. It has the same corrosion resistance as the comparative material of No. 11. The results of the cost estimation also show that the sample No. In Nos. 7 to 10, sample No. of the comparative material. Although it is 0.9 to 1.5 times as large as that of No. 12, when the life extension of the product due to the performance improvement is taken into consideration, the effect still remains. On the other hand, sample No. of the comparative material. No. 11 carries out Al diffusion infiltration treatment,
The cost has increased significantly.

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

The coating film of the corrosion-resistant / oxidation-resistant material of the present invention has been considered to be the best in the past.
It has oxidation resistance and corrosion resistance equal to or higher than that of the 1-diffusion permeation treatment layer, and the cost can be reduced by about 15 to 55%.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a corrosion-resistant / oxidation-resistant material according to the first aspect of the present invention.

FIG. 2 is a configuration diagram of a corrosion-resistant / oxidation-resistant material according to the second aspect of the present invention.

FIG. 3 is a configuration diagram showing an example of a conventional corrosion-resistant / oxidation-resistant material.

FIG. 4 is a configuration diagram showing another example of a conventional corrosion-resistant / oxidation-resistant material.

Claims (2)

[Claims] 1. A CoAl single phase alloy containing 44 to 56 atomic% of Al on the surface of a base material by low pressure plasma spraying or 3
A corrosion-resistant / oxidation-resistant material, characterized in that a metal layer of a FeAl single-phase alloy containing 4 to 48 atomic% of Al is formed. 2. A MCrAlY (M: Ni, Co, Fe selected from the group consisting of one of the following:
CoA single phase alloy containing 34 to 56 atomic% of Al by a low pressure plasma spraying method, or a metal layer of 34 to 48 atomic%. 2. A corrosion-resistant and oxidation-resistant material, characterized in that a metal layer of a FeAl single-phase alloy containing Al is formed.