JP2002115081A - Method of forming aluminide containing active element as non-bonded and bonded coating and coated member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process of forming improved aluminum containing one or more kinds of oxygen activating elements. SOLUTION: A metallic base material is subjected to overlay coating (for example, MCrAL coating) containing >=1 kinds of the oxygen active elements (for example, yttrium, hafnium and silicon) by a general overlay process like low-pressure plasma thermal spraying. Metal (more preferably the transition metal of group VIII, as platinum) is applied by, for example, electroplating onto the base material. The base material is subjected to aluminization by, for example, chemical vapor deposition and is more preferably subjected to heat treatment in succession thereto. Further, thermally insulating ceramics is applied thereto. The aluminide coating containing the active elements having the stable composition and improved durability may be thereby obtained. Such coating may be utilized as the independent type coating and as the bonded coating for the thermally insulation coating to be applied in succession.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating having oxidation resistance and corrosion resistance, and more particularly to a coating containing one or more kinds of active elements.
The present invention relates to an aluminide coating having improved oxidation resistance and corrosion resistance.

[0002]

BACKGROUND OF THE INVENTION Overlay coatings are used to provide the underlying substrate with oxidation and corrosion resistance at elevated temperatures, either as a stand-alone coating or as an adhesive bond for a subsequently applied ceramic insulation layer. As a coating,
It is widely used in high temperature environments and environments where corrosion occurs (eg, inside gas turbine engines). Common overlay coatings are MCr type, MCrAl
Or MCrAlY type coatings, such coatings are applied to gupta or the like,
U.S. Pat. No. 4,585,585, owned by the assignee of the present invention.
481 and Reissue Patent No. 32,121. M is selected from the group consisting of nickel, cobalt, iron and combinations of these elements. Y usually means yttrium, but silicon and / or other active elements (eg hafnium)
This is also included in this. The overlay coating is generally, but not necessarily, applied by plasma spraying. For example, US Pat. No. 4,321,311
See U.S. Patent No. 4,585,481 and Reissue Patent No. 32,121. By other methods,
It is also possible to apply an overlay coating. This method includes, but is not limited to, electron beam physical vapor deposition, chemical vapor deposition, cathodic arc and electroplating. Although the thickness of the bond coat can vary depending on the particular composition and application, the bond coat thickness shown is typically less than about 5 mils.
However, the coating thickness may be larger or smaller.

[0003] Aluminide coatings have also been used to provide the underlying substrate with oxidation and corrosion resistance at elevated temperatures, either as a stand-alone coating or as an adhesive bond coating for a subsequently applied ceramic thermal barrier. Are used in high-temperature environments and in environments that are easily corroded (for example, inside gas turbine engines). Certain aluminide coatings further include one or more noble metals, which provide improved erosion and / or corrosion resistance. For example, U.S. Patent No. 5,856 to Murphy
See No. 027. Such noble metal-containing aluminide coatings are typically applied by a container process or chemical vapor deposition (CVD). In a typical "container" process, the component to be coated is usually first electroplated with a noble metal, followed by a source containing aluminum, an activator (eg, a halide) and an inert material (eg, alumina). Placed inside the container. Subsequently, the container and the member are heated to generate gaseous aluminum, which reacts with nickel or cobalt in the member to form an aluminide. By subjecting the coating to additional heat treatment, a coating having desired properties can be formed. In a typical CVD process, gaseous aluminum is generated by individual generators,
This aluminum gas is sent to the heated member in the chamber to be coated. The aluminum gas reacts with nickel or cobalt in the member to form an aluminide.

[0004] It is generally considered that it is difficult to consistently form high quality aluminides containing active elements. Moreover, it is generally considered that it is generally difficult to form a constant aluminide coating containing a plurality of types of active elements.

A number of patents disclose various overlay coatings and aluminide coating compositions and processes. Examples of these patents are shown below.

US Pat. No. Re. 32,121 discloses a bond coating of the MCrAl type (M includes nickel, cobalt and combinations thereof) by plasma spraying, the MCrAl comprising:
About 0.1-0.7% silicon and 0.1-2% hafnium.

US Pat. No. 4,897,315 discloses a NiCoCrAlY overlay by plasma spraying, which is subsequently aluminized so that an aluminide coating is formed on the substrate. ing.

US Pat. No. 5,658,614 discloses a platinum aluminide coating (without MCrAl) formed by electroplating platinum on a substrate and then aluminizing by CVD. I have.

[0009]

SUMMARY OF THE INVENTION The main object of the present invention is to:
It is to provide a coating with improved properties.

Another object is aluminide coating,
And to provide a process for applying an aluminide with improved resistance.

Yet another object is to provide a process for forming an aluminide coating containing active elements and consistently of high quality.

[0012]

According to one aspect of the present invention, a method for improving the corrosion and oxidation resistance of a substrate is disclosed. In this method, a superalloy substrate is formed,
Subsequently, at least one
An overlay coating containing various oxygen active elements is applied on the substrate. Platinum and other Group VIII transition metals are applied over the overlay coating. Subsequently, the overlay coating and the metal are aluminized, for example by chemical vapor deposition. A further ceramic thermal barrier coating can be applied. Coated members are also disclosed.

[0013]

DETAILED DESCRIPTION OF THE INVENTION Turning now to FIG. 1, a substrate with an aluminide coating of the present invention is indicated by the reference numeral 10. The coating may be used as a stand-alone coating, for example, to provide oxidation resistance at elevated temperatures, or as an adhesive bond coating for a subsequent thermal barrier, such as a layer of ceramic material (eg, stabilized zirconia). Can be.
In the embodiment shown in FIG. 1, a ceramic layer is applied over the aluminide to form a thermal insulation layer. The ceramic layer can be a stabilized zirconia as disclosed in U.S. Pat. No. 4,321,311 to Strangman or U.S. Patent Application No. 09 / 164,700 to Maloney. These patents are:
It is owned by the assignee of the present invention and expressly discloses this point.

Substrate 12 is typically a nickel, cobalt and / or iron based superalloy material. FIG.
As described in more detail below with reference to
An overlay coating 14, such as an rAl-type coating, is coated with one or more oxygen active elements, preferably by low pressure plasma spraying.
element) (eg, hafnium, yttrium, silicon, etc.) first on the substrate. Subsequently, a metal (eg, a transition metal of Group VIII such as platinum)
, Preferably by electroplating, followed by aluminization to form an adherent alumina layer 16. In addition, heat treating the component results in the coating having desired properties (eg, improved mechanical properties). As shown in FIG. 3, the present invention results in coatings having improved properties (eg, corrosion resistance, oxidation resistance and resistance) over conventional coatings. Although the inventions described below utilize nickel-based, cobalt-based, or iron-based superalloy materials, the invention is not limited to the use of these materials.

The general composition of such an alloy is shown in Table 1. Examples of U.S. Patents that disclose columnar crystal alloys, single crystal alloys and oriented solidified alloys include U.S. Pat. Nos. 4,209,348 and 4,717,
Nos. 432, 4,719,080 and 5,068,
No. 084, each of which explicitly discloses this point. The cooling holes may be located at one or more locations on the turbine blade, but as is well known in the art, providing such cooling holes allows for the specific formation of the airfoil during operation. Cooling air can flow over the part.

[0016]

[Table 1]

Other alloys include, for example, Rane N4 and CMSX-2 described in the prior art.

Usually, the active element is, for example, MCr type or MC
As part of the rAl type overlay coating, it is applied by a common overlay process. At this time,
It is possible to incorporate other elements or not. In the present invention, MCr
An overlay coating such as Al is applied to the substrate surface by a common overlay process such as low pressure plasma spraying. The overlay can be applied by other methods. This method includes, but is not limited to, e.g., electron beam physical vapor deposition, cathodic arc, electroplating, sputtering and physical vapor deposition. As is well known, M means nickel, cobalt, iron and mixtures thereof. Preferably, the bond coating includes at least one oxygen active element (eg, yttrium, hafnium, silicon, etc.). The overlay coating of the present invention, when applied, has a thickness of about 1-5 mils (0.001-0.07 mil).
Preferably, the thickness of the coating can be different.

As an example of an overlay coating that has been successfully utilized (further exemplified below), NiCo doped with Y, Hf and / or Si
CrAl coating. In a broader form,
Such coatings may have about 5-40 wt. % C
r, about 8 to 35 wt. % Al, about 2 wt. % Y, about 0.1-7 wt. % Si, about 0.1 to 5.5 w
t. % Hf and the remaining amount of Ni and / or Co.

Subsequently, one or more types of VIs
A Group II transition metal is deposited over the MCrAl coating. The coating ultimately comprises about 1 to 30 wt. %, More preferably about 5-20 wt. %, And as described below, about 10-11 wt. % Pt
, Good results were obtained. Such metals are preferably deposited by electroplating in a well-known manner, but those skilled in the art will recognize that the transition metal can be applied simultaneously with the overlay coating. Metal is added to about 0.05-0.15 mil (0.001
27-0.00381 mm), the final transition metal content of the coating is
This is the desired amount described above. Although the present invention preferably utilizes platinum, other metals (eg, palladium,
It is also possible to use iridium, rhodium, ruthenium, osmium and combinations of these elements). The plating process is generally well known and will not be described in detail herein. As an alternative embodiment, such a metal can be applied by jet vapor deposition (JDP), cathodic arc or CVD. For example, US Pat. No. 4,788,082 discloses jet vapor deposition.
And Jet Process Corporation (Jet Proces
See, e.g., U.S. Pat.

Subsequently, aluminum is applied to this part. Preferably, chemical vapor deposition is used to aluminize this portion, but it is also possible to use physical vapor deposition or other suitable deposition methods. The aluminization step by CVD is generally well known and will not be described in detail in the present application. % And some aluminum coating gas (Vol.%). The aluminum coating gas can be formed by passing a carrier gas through an aluminum source. The above process is adjusted as desired so that a predetermined amount of aluminum is applied to the surface of this portion. Subsequently, usually about 180
0-2200 ° F (about 982-1204 ° C), preferably about 1950-2000 ° F (about 1066-1093).
With the substrate heated to (.degree. C.), an aluminum coating gas impinges on the heated substrate at a predetermined transfer rate.

After aluminization, the coated portion is subjected to diffusion heat treatment. However, in some cases, diffusion heat treatment is unnecessary.
Using the example described above, the diffusion heat treatment is preferably carried out for a sufficient period of time (eg, 3 hours), and the member is typically about 197
Heat to a temperature of 5 ° F. (about 1079 ° C.), followed by a precipitation heat treatment, for example, at about 1600 ° F. (about 871 ° C.) for about 16 hours. Temperatures and times can vary depending on composition and desired properties, and generally higher temperatures can reduce times. The coating formed is shown in FIG. 1, which is followed by a ceramic insulation layer with cylindrical particles.

As mentioned above, the coating of the present invention can be used as a stand-alone coating or as an adhesive coating for a subsequently applied ceramic thermal barrier coating. Typical ceramics are based on zirconia and can be partially or completely stabilized by adding yttria or other suitable stabilizers. Yttria stabilized zirconia (YS
Examples of ceramic coatings consisting of Z) are, for example,
U.S. Pat. No. 4,321,31 owned by the assignee of the present invention.
No. 1 and 5,262,245.
Such ceramics can be applied by EB-PVD, plasma spraying or other suitable methods.

Samples were formed using a superalloy substrate according to the present invention, some of which were further provided with a standard zirconia-based cylindrical thermal barrier coating. The overlay coating as described above was applied by low pressure plasma spraying and subsequently plated with platinum in a known manner. These samples were prepared at approximately 80 Vol. % Carrier gas (eg hydrogen) and about 20 Vol. % Alumina coating gas (in this case, AlCl ₃ ). The coating gas is HCl of about 600
Formed by passing through a source of aluminum at ℃. The substrate is about 1950-2000 ° F (about 1066-1
While heated to a nominal temperature of (093 ° C.), such a coating gas was impinged on the heated substrate at a transfer rate of about 224 standard cubic feet / minute. Subsequently, some samples were provided with a ceramic thermal barrier coating of yttria-stabilized zirconia, for example as described in the above-referenced Strangman '311, and the remaining samples were coated with this material. The test was performed without such a ceramic coating.

The parts coated according to the invention were tested on a burner rig. Tests performed on samples subsequently applied with a thermal barrier have shown that the resistance of the coatings according to the invention is 2% of the current TBC.
It was found to be ~ 3 times. Parts coated in accordance with the present invention were also tested as a single coating (eg, a ceramic layer without an overlay coating) and found to have improved protection and resistance as well.

The samples were further tested on a hot burner rig. In this test, every cycle, along with a standard platinum aluminide,
Exposure to 2150 ° F (117 ° C) for 117 minutes,
Subsequently, it was exposed to cooling air for 3 minutes. Samples formed in accordance with the present invention had approximately 2.5 times longer life than standard aluminide-treated samples.

According to the test results, the composition of the coating finally obtained by the present invention has a Pt of about 1 to 30 wt.
%, About 2 to 4.5 wt. %, Al is about 13-14
wt. %, Hf is 1 to 5.5 wt. %, And Ni, C
o and Cr are the remaining amounts, and more preferably, Pt is about 10-11 wt. %, About 2.6 to 4.2 wt.
%, Al is about 13.4-13.6 wt. %, Hf is 3.
9 to 5.3 wt. % And Ni, Co and Cr are considered to be the remaining amount. Other compositions should have a much improved lifetime (with or without a thermal barrier coating) over known aluminide coatings.

The present invention provides significant advantages over conventional processes. This improved process makes it possible to form aluminide coatings containing active elements and having a very stable composition, whereby the properties can be made very stable and the resistance can be improved. The resistance of the resulting coating,
It will be improved as well.

While the present invention has been described in detail, it has been described without departing from the spirit of the invention and the scope of the appended claims.
Major changes and replacements are also possible. Accordingly, it is to be understood that the present invention has been described by way of example and not limitation.

[Brief description of the drawings]

FIG. 1 is a micrograph of a coating of the present invention having a ceramic coating.

FIG. 2 is a flow chart of a preferred process for forming the coating of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01D 5/28 F01D 5/28 F02C 7/00 F02C 7/00 C (72) Inventor Walter E. Olson United States, Connecticut, Vernon, Winding Brook Trail 46 (72) Inventor David N. Dale United States, Connecticut, Newington, Beacon Street 31F Term (Reference) 3G002 EA05 EA06 EA08 4K024 AA12 AA15 AB02 AB03 AB15 AB19 BA01 BB01 DA10 DB01 DB10 GA04 GA16 4K031 AA02 AB02 AB08 CB22 CB26 CB27 DA04 FA01 BA06 BA06 BA06 BA04 BA12 BB04 BC11 CA11 CA13 CA14 CA18 CA62

Claims (33)

[Claims] 1. A method for improving the corrosion and oxidation resistance of a substrate, comprising: forming a superalloy substrate; and overlaying the MCrAl overlay coating containing at least one oxygen active element by an overlay step. Applying a Group VIII transition metal onto the overlay coating; and aluminizing the overlay coating and the metal. 2. The method of claim 1, wherein the overlay coating is nominally about 5-40 wt. % Cr, about 8 to 35 wt. %
Al, up to about 2% Y, about 0.1-7 wt. % S
i, about 0.1-5.5 wt. % Hf and remaining amount N
2. The method according to claim 1, comprising i and / or Co. 3. The step of applying the overlay coating containing at least one oxygen active element is performed by a process selected from the group consisting of plasma spraying, low pressure plasma spraying, sputtering, cathodic arc, electroplating and physical vapor deposition. The method of claim 1, wherein: 4. The method of claim 1, wherein the step of applying the transition metal is performed by a process selected from the group consisting of electroplating, jet vapor deposition, physical vapor deposition, sputter, and cathodic arc. The described method. 5. The method of claim 1, wherein said aluminizing step is performed by a process selected from the group consisting of chemical vapor deposition, jet vapor deposition, and physical vapor deposition. 6. The method of claim 1, wherein said Group VIII transition metal is selected from the group consisting of platinum, palladium, iridium, rhodium, ruthenium and osmium. 7. The method of claim 6, wherein said metal is platinum. 8. The method of claim 1, including the step of subjecting said member to a heat treatment. 9. The method according to claim 1, further comprising the step of depositing a thermal insulating ceramic on said aluminide.
The described method. 10. The method of claim 1, wherein said ceramic comprises stabilized zirconia. 11. A method for improving the oxidation resistance of a substrate, comprising: forming a substrate comprising a nickel and / or cobalt based superalloy material; Applying an overlay coating containing an oxygen-active element on the substrate; applying a Group VIII transition metal on the substrate by electroplating; the bonding coating; the at least one oxygen-active element And aluminizing the metal by chemical vapor deposition to form an aluminide on the substrate. 12. The method according to claim 11, wherein the overlay coating comprises yttrium, hafnium and / or silicon. 13. The overlay coating, wherein the overlay coating is nominally about 5-40 wt. % Cr, about 8 to 35 wt.
% Al, up to about 2% Y, about 0.1-7 wt. % S
i, about 0.1-5.5 wt. % Hf and remaining amount N
The method according to claim 11, comprising i and / or Co. 14. The metal according to claim 11, wherein the metal is platinum, palladium,
The method of claim 11, wherein the method is selected from the group consisting of iridium, rhodium, ruthenium, and osmium. 15. The method of claim 11, wherein said metal is platinum. 16. The method of claim 11, including the step of subjecting the member to a heat treatment. 17. The method of claim 11, including depositing a thermal insulating ceramic over said aluminide. 18. The method of claim 11, wherein said ceramic comprises stabilized zirconia. 19. A superalloy member having a coating with improved corrosion resistance, oxidation resistance and resistance, comprising: forming a superalloy substrate; and overlaying at least one oxygen active element by an overlay process. A superalloy member comprising the steps of: applying an overlay coating containing the coating on the substrate; applying a metal over the overlay coating; and aluminizing the overlay coating and the metal. 20. The overlay coating according to claim 1, wherein said overlay coating is nominally about 5-40 wt. % Cr, about 8 to 35 wt.
% Al, up to about 2% Y, about 0.1-7 wt. % S
i, about 0.1-5.5 wt. % Hf and remaining amount N
20. The superalloy member according to claim 19, comprising i and / or Co. 21. The step of applying an overlay coating containing at least one oxygen-active element, comprising: air plasma spraying, low pressure plasma spraying, sputtering,
The superalloy member according to claim 19, wherein the superalloy member is formed by a process selected from the group consisting of cathodic arc, physical vapor deposition, and electroplating. 22. The superalloy member of claim 19, wherein said step of applying a metal is performed by a process selected from the group consisting of electroplating, jet vapor deposition, and physical vapor deposition. 23. The superalloy member of claim 19, wherein said aluminizing step is performed by a process selected from the group consisting of chemical vapor deposition, jet vapor deposition, and physical vapor deposition. 24. The metal is platinum, palladium,
The superalloy member according to claim 19, wherein the member is a Group VIII transition metal selected from the group consisting of iridium, rhodium, ruthenium, and osmium. 25. The superalloy member according to claim 19, wherein said metal is platinum. 26. The superalloy member according to claim 19, further comprising a step of performing a heat treatment on the member. 27. The superalloy member of claim 19, including the step of depositing a thermal insulating ceramic over said aluminide. 28. The superalloy member according to claim 19, wherein said ceramic is made of stabilized zirconia. 29. The superalloy member of claim 28, wherein the zirconia is stabilized by yttria or gadolinia. 30. The coating formed is nominally about 5-40 wt. % Cr, about 8 to 35 wt. % Al, about 5-20 wt. % Group VIII transition metal, about 2 wt. % Y, about 0.1-7 wt. % Si, about 0.1-5.5 wt. % Hf and the remaining amount of Ni and C
The superalloy member according to claim 1, comprising o and Cr. 31. The coating of claim 1, wherein said coating is nominally about 9-12 wt. % Pt, about 13-14 wt. % A
l, about 3.9-5.5 wt. % Hf, about 2.5-4.
5 wt. 31. The superalloy member according to claim 30, wherein the superalloy member is composed of% Si and the balance of Ni and / or Co. 32. The coating formed is nominally about 5-40 wt. % Cr, about 8 to 35 wt. % Al, about 5-20 wt. % Group VIII transition metal, about 2 wt. % Y, about 0.1-7 wt. % Si, about 0.1-5.5 wt. 2. The method according to claim 1, comprising% Hf and the balance Ni and / or Co. 33. The coating of claim 1, wherein the coating is nominally about 9-12 wt. % Pt, about 13-14 wt. % A
l, about 3.9-5.5 wt. % Hf, about 2.5-4.
5 wt. 33. The method according to claim 32, comprising% Si and the balance Ni and / or Co.