JPH0853748A - Production of thermal spraying-coated superalloy member - Google Patents

Abstract

PURPOSE:To provide a method for a thermal spraying-coated superalloy member improved in high temp. corrosion and oxidation resistance and capable of withstanding use at a high temp. for long time by forming sprayed coating having a uniform aluminum concn. distribution on the surface. CONSTITUTION:The surface of an Ni-base or Co-base superalloy base material is coated with thermally spraying powder of an MCrAl-base alloy or the like having a coating layer constituted of Al or an intermetallic compound contg. Al and Ni or an intermetallic compound contg. Al and Co by thermal spraying. Moreover, in the method for producing the same thermally spraying-coated superalloy member, the surface of the superalloy base material is thermal- sprayed with thermally spraying powder of an MCrAl-base alloy or the like having no coating layer essentially consisting of Al or the like to form coating, and after that, in the vicinity of the surface of the sprayed coating thereon, thermally spraying powder having the same coating layer is thermal-sprayed to form coating having 20 to 150mum thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention coats a nickel-based or cobalt-based superalloy substrate with a sprayed powder of a corrosion-resistant / oxidation-resistant alloy by plasma spraying to improve oxidation resistance and corrosion resistance at high temperatures. A method of manufacturing a thermal spray coated superalloy member having the same.

[0002]

2. Description of the Related Art Generally, a member such as a moving blade, a stationary blade or a combustor of a gas turbine, which is exposed to a high temperature of 1000 ° C. or more for a long time, has a high temperature strength of nickel (Ni) group or cobalt (Co) A base super heat-resistant alloy (super alloy) is used. Since such superalloys do not have sufficient resistance to oxidation and corrosion, the surface of the base material is coated by flame spraying or plasma spraying of a specific alloy powder to prevent corrosion and oxidation. We are trying to improve sex.

That is, regarding plasma spray coating of superalloys, MCr-based alloys (M is iron, cobalt, nickel,
A method of plasma spraying at least one element selected from aluminum) powder in an inert atmosphere of argon and hydrogen gas to reduce oxidation during vapor deposition of heated particles is disclosed in US Pat. It is written in the book. Further, in this method, in order to increase the deformation resistance of the vapor-deposited particles during cooling, melting of the particles is avoided, and heated particles, rather than molten particles, are jetted to collide with the base material. Also, Howard's Japanese patent
1-119657), a dispersion material selected from alumina, thoria and yttria is dispersed in a powder containing at least one element selected from chromium, iron, cobalt and nickel by high energy milling. Sprayed powder,
Flame spraying on superalloy substrates is described.

However, in a member having a superalloy as a base material, corrosion resistance and oxidation resistance at a higher temperature are required as the use environment becomes more severe, but the conventional method described above sufficiently satisfies the requirement. I couldn't do it.

Therefore, in order to meet the requirements for corrosion resistance and oxidation resistance at high temperatures, the following two methods have been studied. That is, one of them is a method of increasing the amount of aluminum contained in the thermal spray powder. However, this method increases the amount of aluminum (eg 10w
Since the thermal sprayed powder containing t% or more) is composed of an intermetallic compound which is a brittle material, it is difficult to form a favorable thermal sprayed layer. Another method is to infiltrate aluminum from the surface of the sprayed layer after spraying. There are two methods, an aluminizing method and a chemical vapor deposition method, which have been widely used in recent years.

A flow chart of FIG. 6 shows a method of forming an aluminum diffusion layer on the surface of a spray-coated superalloy member by an aluminizing method and a chemical vapor deposition method. In the aluminizing method, the surface of the base material made of superalloy is first roughened by blasting, and then,
A sprayed powder of MCrAl-based alloy (where M represents at least one element of nickel and cobalt),
Coat under reduced pressure or by plasma spraying in argon. Then, after reducing the irregularities on the surface of the sprayed layer thus formed by polishing, the sprayed coating superalloy member is sealed in a container together with a powder containing aluminum as a main component, and then heated (aluminizing), so that the member ( Aluminum is diffused and permeated from the surface of the sprayed layer. Further, in the chemical vapor deposition method, after unevenness on the surface of the sprayed layer is similarly reduced by polishing, the sprayed coating superalloy member is brought into contact with steam containing aluminum in a heated state, and the surface of the member (sprayed layer) is removed. Diffuses and penetrates aluminum.

[0007]

However, in both the aluminizing method and the chemical vapor deposition method, since the diffusion of aluminum from the surface of the sprayed layer is used, the heating time is long. There was a problem. That is, as is well known, the sprayed layer is porous,
Because aluminum diffuses through the contact surfaces between the powders,
There is a problem that the heating time for obtaining a predetermined aluminum diffusion layer becomes long.

If it is desired to form the aluminum diffusion layer only on a limited partial area of the surface of the member, it is necessary to mask unnecessary areas. For example, in a turbine blade or stationary blade of a gas turbine, aluminum needs to be diffused in the part exposed to high-temperature gas, but it is not necessary to diffuse aluminum in the root part that supports the blade, nor is a sprayed layer necessary. . Therefore, in the aluminizing method, a powder of a component that suppresses the diffusion of aluminum is blended in the vicinity of the masked area, and in the chemical vapor deposition method, the masked area is metalized so as to prevent the invasion of vapor containing aluminum. Shielding is done with a container made of, and in any method,
There is a problem that complicated work or a jig is required for masking. Further, although there are large irregularities on the surface of the thermal sprayed layer after thermal spraying, the diffusion of aluminum is fast at the concave portions on the surface and slow at the convex portions, so the aluminum diffusion layer has a shape corresponding to the irregularities on the surface. Therefore, in order to obtain an aluminum diffusion layer with a uniform thickness, the irregularities on the surface of the sprayed layer should be
There is a problem that it is necessary to polish it to be 0.01 mm or less, and it is necessary to polish it even after the aluminum diffusion treatment, which requires many processes for the production and the production cost is high.

Further, in any of the aluminizing method and the chemical vapor deposition method, aluminum is an oxide of aluminum, which is an oxide of aluminum. A dense layer of is formed. Therefore, the high temperature oxidation resistance during use is improved, but there is a disadvantage that an aluminum-deficient layer is formed in the vicinity of the alumina layer due to the formation of alumina. That is, since the aluminum concentration on the surface of the sprayed layer in which aluminum is diffused is not uniform and decreases from the surface toward the substrate, if some kind of impact causes peeling of a part of the alumina layer, or for a long time. In the case where the alumina layer decreases due to the use of Al, the supply of aluminum is not sufficient, and the formation of alumina is less likely to occur quickly. Therefore, there is a drawback that it is difficult to suppress the progress of oxidation and corrosion.

The present invention has been made to solve these problems. By forming a thermal spray coating having a uniform aluminum concentration distribution on the surface, it is possible to improve corrosion resistance and oxidation resistance at high temperatures, and to achieve long-term corrosion at high temperatures. It is an object of the present invention to provide a method for producing a spray-coated superalloy member that can withstand the use of time.

[0011]

The method for producing a spray-coated superalloy member according to the present invention comprises: a nickel-based or cobalt-based superalloy substrate; aluminum; or an intermetallic compound containing aluminum and nickel; or aluminum. Corrosion resistance with a coating layer consisting of an intermetallic compound containing cobalt and cobalt
It is characterized in that a thermal spraying powder of an oxidation resistant alloy is coated by thermal spraying.

Further, in such a method for producing a spray-coated superalloy member, a coating is formed on the superalloy substrate by spraying a sprayed powder of a corrosion-resistant / oxidation-resistant alloy having no coating layer. After that, the thermal spraying powder having the coating layer is sprayed in the vicinity of the surface of the thermal sprayed coating thereon to form a coating having a thickness of 20 to 150 μm.

In the manufacturing method of the present invention, as the superalloy constituting the base material, a superalloy containing nickel or cobalt as a main component and having an arbitrary composition can be selected. Typical nickel-based superalloys that can be used include, for example, IN-738, MAR-200, NX-188, Reno95, TAZ-8B, TRWV.
Examples of the cobalt-based superalloy include FSX-414, FSX-430, MAR-M509, and X-45.

Further, as a thermal spraying powder for forming a coating by thermal spraying on the surface of the base material made of such a superalloy, any powder containing nickel and / or cobalt as a main component and chromium and aluminum as essential components is used. On the surface of the MCrAl-based alloy (M represents at least one element selected from nickel and cobalt) having a composition, aluminum, or an intermetallic compound containing aluminum and nickel, or aluminum and cobalt is formed on the surface of the powder. A powder having a coating layer made of an intermetallic compound containing is used. Here, the above-mentioned MCrAl-based alloy includes, for example, molybdenum, tungsten, titanium, zirconium,
Alternatively, a metal element such as yttrium or another rare earth element can be appropriately mixed.

In the present invention, as a method for forming the above-mentioned coating layer containing aluminum as a main component on the surface of the MCrAl-based alloy powder, (a) a chemical vapor deposition method and (b) a high energy ball mill method. , (C) high energy powder mixing method. (C) is in terms of mechanical alloying method (mechanical alloying method).
It is considered that it is almost the same as
Both methods (b) will be described.

(A) Chemical Vapor Plating Method An example of a chemical vapor plating apparatus for producing a thermal spray powder having a coating layer such as Al is schematically shown in FIG. This apparatus 1 comprises a supply apparatus 2 for Al or the like and an elongated cylindrical furnace 3 for coating Al, and a coating base 4 is arranged in several stages in the coating furnace 3. In such an apparatus, a container 6 containing powder 5 of MCrAl-based alloy or the like was placed on a coating base 4, the inside of the coating furnace 3 was replaced with argon, and then placed outside the furnace 3. Container 6 by heater 7
While heating the powder 5 together, the vapor 8 of the compound containing Al such as AlCl is supplied from the supply device 2 through the vapor pipe 9 so that Al permeates and diffuses from the surface of the powder 5. In this chemical vapor deposition method, it is preferable to use the powder container 6 surrounded by a mesh having a mesh smaller than the average particle size of the powder 5 as the powder container 6 so that the above-mentioned vapor can flow through easily. Desirably, the powder 5 itself has a very poor thermal conductivity, so that the powder 5 is sufficiently heated in advance and then steam is supplied.

In this method, the thickness of the coating layer formed mainly on Al or the like formed on the surface of the powder 5 is controlled by the heating temperature and time, so that the thermal spray powders having different coating layer thicknesses in one batch can be obtained. Can be manufactured simultaneously. That is, since the heating temperature of the heater 7 can be adjusted separately for each stage, the thickness of the coating layer is changed for each coating base 4 and the thickness of the coating layer is different. Several types of thermal spray powders can be produced. Therefore, this method is suitable for producing a small amount of a variety of thermal spraying powders, as compared with suppressing the amount of Al by a powder production method that produces a large amount of one batch such as a normal atomization method.
Great cost advantage.

(B) High-energy ball mill method An example of a high-energy ball mill device for producing a thermal spray powder having a coating layer containing Al as a main component is schematically shown in FIG. This device 10 comprises a rotatable pot 11
And a ball 12 housed therein to facilitate mixing of the powder
The ball 12 is made of the same material as the powder 13 such as MCrAl-based alloy, which is the powder to be mixed, in order to suppress the mixing of impurities into the powder. In such an apparatus, a powder 13 such as an MCrAl-based alloy and a powder 14 such as Al or an intermetallic compound containing Al and Ni are put in the pot 11 and rotated together with the pot 11. And in the pot 11, the MC sandwiched between the two balls 12
Powder 13 such as rAl-based alloy and powder 14 such as Al described above
And are plastically deformed, and particularly the ductile powder 14 of Al or the like is remarkably deformed to be attached so as to surround the periphery of the powder 13 of MCrAl-based alloy or the like. Thus, MCr
The surface of the powder 13 such as an Al-based alloy is coated with the powder 14 containing Al as a main component, and a thermal spraying powder in which both are bonded by mechanical force is obtained. It is possible to increase the adhesiveness of and secure the bonding.

In the present invention, MC is obtained by these methods.
The thickness of the coating layer mainly composed of Al or the like formed on the powder surface of the rAl-based alloy or the like is preferably 1 to 15 μm. If the thickness of the coating layer is less than 1 μm, there is almost no effect of improving the high temperature corrosion resistance by forming the coating layer.On the contrary, if the thickness exceeds 15 μm, embrittlement of the thermal spray powder proceeds and good thermal spray coating can be obtained. Absent.

In the present invention, a coating layer containing Al or the like as the main component is formed only on the surface by the chemical vapor deposition method, the high energy ball mill method, or the high energy powder mixing method described above, and the vicinity of the central portion is formed. By leaving the MCrAl-based alloy or the like, which is the original powder component, in the powder, a thermal spray powder with reduced embrittlement is manufactured. Then, by performing plasma spraying on the surface of the superalloy substrate using such a sprayed powder, it is possible to form a sprayed coating having good characteristics. The procedure of thermal spraying is shown in FIG. That is, first, after blasting the surface of the superalloy substrate, the thermal spraying powder having a coating layer such as Al is plasma sprayed under an inert gas or under reduced pressure. Next, in order to improve the adhesion of the thermal sprayed layer and to make the aluminum distribution in the thermal spray coating uniform, after the diffusion heat treatment, the surface of the thermal spray coating is smoothed by polishing. The cross-sectional structure of the thermal spray coating superalloy member thus obtained,
As shown in FIG. In the figure, reference numeral 15 indicates a superalloy substrate, and 16
Indicates a thermal spray coating of a thermal spray powder having a coating layer such as Al.

Further, in the present invention, on the superalloy substrate,
First, a thermal spraying powder such as an ordinary MCrAl-based alloy having no coating layer such as Al is sprayed, and then a thermal spraying powder having a coating layer such as Al is sprayed thereon, and only the surface vicinity is sprayed with Al enriched. It can be a coating. The cross-sectional structure of the spray-coated superalloy member thus obtained is schematically shown in FIG.
In the figure, reference numeral 17 indicates a thermal spray coating of a thermal spray powder such as MCrAl-based alloy, and 18 indicates an Al-enriched thermal spray coating formed by thermal spray coating of a thermal spray powder having a coating layer such as Al. Here, the thickness of the sprayed coating 18 enriched with Al is 20
~ 150μm is desirable. That is, this Al
When the thickness of the thickened coating 18 is less than 20 μm, for example, when the burner rig test is performed, the coating hardly remains, and the effect of improving the high temperature corrosion resistance and the like due to the formation of the thickened coating 18 is hardly seen. On the contrary, if the thickness of the Al-enriched coating 18 is
If it exceeds 150 μm, the brittleness of the entire thermal spray coating increases significantly, which is not preferable.

[0022]

In the production method of the present invention, by forming an aluminum-concentrated layer having a uniform concentration on the surface layer of the thermal spray coating, it is possible to obtain a good coating that can be used for a long time at a high temperature and whose characteristics do not change. Therefore, it is possible to improve the corrosion resistance and the oxidation resistance of the spray-coated superalloy member at high temperatures.

[0023]

Embodiments of the present invention will be described below.

EXAMPLE Cr29wt% -Al6wt% -Y1wt% -C was formed by the chemical vapor deposition method or the high energy ball mill method described above.
o On the powder surface of the alloy (Co-29Cr-6Al-1Y alloy) consisting of the balance, a coating layer containing Al or the like as a main component and having a thickness of several μm is formed, and the thermal spray powder thus obtained is used to form a superalloy base. The surface of the material was sprayed. That is, after blasting the surface of a substrate made of IN738, Co-
The 29Cr-6Al-1Y alloy powder was spray-coated to a thickness of 180 μm, and the spray-coated powder having a coating layer such as Al was spray-coated to a thickness of 20 μm thereon.

For comparison, a Co-29Cr-6Al-1Y alloy powder was formed on the surface of the same superalloy substrate as in the example.
Thermal spray coating member having a thickness of 00 μm (Comparative Example 1)
Then, a member (Comparative Example 2) in which the thermal spray coating thus obtained was further subjected to aluminizing treatment by a conventional method was prepared.

Next, a hot corrosion burner rig (HCBR) test was carried out on each of the spray-coated members obtained in the examples and comparative examples as a simulation test under high corrosion conditions experienced in a gas turbine. In this test, the thermal spray coating was exposed to a burner at a temperature of 1200 ° C obtained by combustion of fuel for gas turbine, and when the exposure time reached 2000 hr, the member was taken out of the test apparatus and the cross-sectional structure of the thermal spray coating was observed. . As a result of the observation, in the Example, almost all layers of the thermal spray coating remained, and there was almost no erosion between particles, whereas in Comparative Example 1, only the thermal spray coating having a thickness of 100 μm remained. It was found that the base material was partially corroded in Example 1, and in Comparative Example 2, almost all the layer of the thermal spray coating remained, but part of the base material was corroded.

Further, with respect to the thermal spray coating members obtained in Examples and Comparative Example 2, the aluminum concentration distribution in the thermal spray coating after the burner rig test was examined, and in the thermal spray coating of Comparative Example 2, a dense alumina surface was obtained. Although a layer was formed, it was found that an aluminum deficient layer was formed near the alumina layer. On the other hand, in the thermal spray coating of the example, it was found that a dense alumina layer was formed on the surface and no aluminum deficient layer was formed in the vicinity thereof. Further, as a result of detailed observation, in Comparative Example 2, the corroded portion between particles found in a part of the thermal spray coating was a portion where the alumina layer was thin or almost absent, and the corroded portion was generated through the aluminum deficient layer. I understood.

As described above, according to the present invention, in the formation of the thermal spray coating on the superalloy substrate, only the surface of the coating is Al
By performing thermal spraying using a thermal spraying powder of MCrAl-based alloy having a coating layer containing, for example, as a main component, a thermal spray coating excellent in corrosion resistance and oxidation resistance at high temperatures can be obtained. Further, by performing the diffusion heat treatment after the thermal spraying, the adhesion of the thermal spray coating can be improved and the aluminum concentration distribution can be made uniform.
Further, the method of the present invention requires a complicated jig or work at the time of masking in order to obtain an aluminum diffusion layer on the surface of thermal spray coating, as compared with the conventional aluminizing method or chemical vapor deposition method. Instead, you only need to attach commercially available gum tape or glass tape. Therefore, the masking work is easy and the manufacturing process can be simplified.

[0029]

As is apparent from the above description, according to the present invention, by forming a coating having a uniform aluminum concentration distribution on the surface of the thermal spray coating, it is possible to improve corrosion resistance and oxidation resistance and It is possible to obtain a spray-coated superalloy member that can be used for a long time.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of a chemical vapor deposition apparatus for producing a thermal spray powder having a coating layer of Al or the like in the production method of the present invention.

FIG. 2 is a diagram schematically showing an example of a high energy ball mill device for producing a thermal spray powder having a coating layer of Al or the like in the production method of the present invention.

FIG. 3 is a flowchart showing a method for manufacturing a spray-coated superalloy member of the present invention.

FIG. 4 is a sectional view showing an example of a spray-coated superalloy member obtained by the present invention.

FIG. 5 is a cross-sectional view showing another example of the spray-coated superalloy member obtained by the present invention.

FIG. 6 is a flow chart showing a conventional method of forming an aluminum diffusion layer on a spray coated surface.

[Explanation of symbols]

 1 ………… Chemical vapor plating apparatus 2 ………… Al supply equipment 3 ………… Coating furnace 5,13 ………… MCrAl-based alloy powder 7 ………… Heater 10 ………… High energy ball mill equipment 11 ………… Pot 12 ………… Ball 14 ………… Al powder etc. 15 ………… Superalloy base material 16 ………… Sprayed coating of sprayed powder having a coating layer such as Al 17 ………… MCrAl based alloy etc. Spray coating of thermal spray powder of 18 ......... Al-enriched thermal spray coating

Front page continued (72) Masahiro Saito, Inventor Masahiro Saito, 4 of 2 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Corporation (72) Masashi Takahashi, 4 Shares, 2 of Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Keihin In the office

Claims (5)

[Claims] 1. A corrosion-resistant and oxidation-resistant material having a coating layer made of aluminum, an intermetallic compound containing aluminum and nickel, or an intermetallic compound containing aluminum and cobalt on a nickel-based or cobalt-based superalloy substrate. A method for producing a spray-coated superalloy member, which comprises coating a sprayed powder of a heat-resistant alloy by spraying. 2. An intermetallic compound containing aluminum or aluminum and nickel on the surface of a corrosion-resistant and oxidation-resistant alloy powder, wherein the thermal spraying powder contains nickel and / or cobalt as main components and chromium and aluminum as essential components. Or a coating layer made of an intermetallic compound containing aluminum and cobalt and having a thickness of 1 to 15 .mu.m. 3. In the production of the thermal spraying powder, a coating layer made of aluminum, an intermetallic compound containing aluminum and nickel, or an intermetallic compound containing aluminum and cobalt is formed by a chemical vapor deposition method. The method for producing a spray-coated superalloy member according to claim 1 or 2. 4. In the production of the thermal spraying powder, a coating layer made of aluminum, an intermetallic compound containing aluminum and nickel, or an intermetallic compound containing aluminum and cobalt is formed by a high energy ball mill method. The method for producing a spray-coated superalloy member according to claim 1 or 2. 5. A coating is formed on the superalloy base material by spraying a sprayed powder of a corrosion-resistant / oxidation-resistant alloy having no coating layer, and then in the vicinity of the surface of the sprayed coating thereon. The method for producing a spray-coated superalloy member according to any one of claims 1 to 4, wherein a coating having a thickness of 20 to 150 µm is formed by spraying a sprayed powder having the coating layer.