Internal airfoil component electrolplating
Method and apparatus are provided for electroplating a surface area of an internal wall defining a cooling cavity present in a gas turbine engine airfoil component.
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This application is a division of copending Ser. No. 14/120,004 filed Apr. 14, 2014, which claims benefit and priority of U.S. provisional application Ser. No. 61/854,561 filed Apr. 26, 2013, the entire disclosures of which are incorporated herein by reference.FIELD OF THE INVENTION
The present invention relates to the electroplating of a surface area of an internal wall defining a cooling cavity present in a gas turbine engine airfoil component in preparation for aluminizing to form a modified diffusion aluminide coating on the plated area.BACKGROUND OF THE INVENTION
Increased gas turbine engine performance has been achieved through the improvements to the high temperature performance of turbine engine superalloy blades and vanes using cooling schemes and/or protective oxidation/corrosion resistant coatings so as to increase engine operating temperature. The most improvement from external coatings has been through the addition of thermal barrier coatings (TBC) applied to internally cooled turbine components, which typically include a diffusion aluminide coating and/or MCrAlY coating between the TBC and the substrate superalloy.
However, there is a need to improve the oxidation/corrosion resistance of internal surfaces forming cooling passages or cavities in the turbine engine blade and vane for use in high performance gas turbine engines.SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for electroplating of a surface area of an internal wall defining a cooling passage or cavity present in a gas turbine engine airfoil component to deposit a noble metal, such as Pt, Pd, etc. that will become incorporated in a subsequently formed diffusion aluminide coating formed on the surface area in an amount of enrichment to improve the protective properties thereof.
In an illustrative embodiment of the invention, an elongated anode is positioned inside the cooling cavity of the airfoil component, which is made the cathode of an electrolytic cell, and an electroplating solution containing the noble metal is flowed into the cooling cavity during at least part of the electroplating time. The anode has opposite end regions supported on an electrical insulating anode support. The anode and the anode support are adapted to be positioned in the cooling cavity. The anode support can be configured to function as a mask so that only certain surface area(s) is/are electroplated, while other areas are left un-plated as a result of masking effect of the anode support. The electroplating solution can contain a noble metal including Pt, Pd, Au, Ag, Rh, Ru, Os, Ir and/or alloys thereof in order to deposit a noble metal layer on the selected surface area.
Following electroplating, a diffusion aluminide coating is formed on the plated internal surface area by gas phase aluminizing (e.g. CVD, above-the-pack, etc.), pack aluminizing, or any suitable aluminizing method so that the diffusion aluminide coating is modified to include an amount of noble metal enrichment to improve its high temperature performance.
The airfoil component can have one or multiple cooling cavities that are concurrently electroplated and then aluminized.
These and other advantages of the invention will become more apparent from the following drawings taken with the detailed description.
The invention provides a method and apparatus for electroplating a surface area of an internal wall defining a cooling cavity present in a gas turbine engine airfoil component, such as a turbine blade or vane, or segments thereof. A noble metal including Pt, Pd, Au, Ag, Rh, Ru, Os, Ir, and/or alloys thereof is deposited on the surface area and will become incorporated in a subsequently formed diffusion aluminide coating formed on the surface area in an amount of noble metal enrichment to improve the protective properties of the noble metal-modified diffusion aluminide coating.
For purposes of illustration and not limitation, the invention will be described in detail below with respect to electroplating a selected surface area of an internal wall defining a cooling cavity present in a gas turbine engine vane segment 5 of the general type shown in
In one application, a selected surface area 20 of the internal wall W defining each cooling cavity 16 is to be coated with a protective noble metal-modified diffusion aluminide coating,
Electroplating takes place in a tank T containing the electroplating solution with the vane segment 5 held submerged in the electroplating solution on electrical current-supply fixture or tooling 27,
Each respective elongated anode 30 extends through the mask opening 25a as shown in
The anode 30 and the anode support 40 collectively have a configuration and dimensions generally complementary to that of each cooling cavity 16 that enable the assembly of anode and anode support to be positioned in the cooling cavity 16 spaced from (out of contact with) the surface area 20 of internal wall W defining the cooling cavity yet masking surface area 21. The anode support 40 is configured with base 40b that functions as a mask of surface area 21 so that only surface area 20 is electroplated. Surface areas 21, 23 are left un-plated as a result of masking effect of the base 40b and integral masking shield 45 of the anode support 40. Such areas 21, 23 are left uncoated when coating is not required there for the intended service application and to save on noble metal costs.
When electroplating a vane segment made of a nickel base superalloy, the anode can comprise conventional Nickel 200 metal, although other suitable anode materials can be sued including, but not limited to, platinum-plated titanium, platinum-clad titanium, graphite, iridium oxide coated anode material and others.
The electroplating solution in the tank T comprises any suitable noble metal-containing electroplating solution for depositing a layer of noble metal layer on surface area 20. For purposes of illustration and not limitation, the electroplating solution can comprise an aqueous Pt-containing KOH solution of the type described in U.S. Pat. No. 5,788,823 having 9.5 to 12 grams/liter Pt by weight (or other amount of Pt), the disclosure of which is incorporated herein by reference, although the invention can be practiced using any suitable noble metal-containing electroplating solution including, but not limited to, hexachloroplatinic acid (H2PtCl6) as a source of Pt in a phosphate buffer solution (U.S. Pat. No. 3,677,789), an acid chloride solution, sulfate solution using a Pt salt precursor such as [(NH3)2Pt(NO2)2] or H2Pt(NO2)2SO4, and a platinum Q salt bath ([(NH3)4Pt(HPO4)] described in U.S. Pat. No. 5,102,509).
Each anode 30 is connected by extensions to electrical current supply anode bus 31 to conventional power source 29 to provide electrical current (amperage) or voltage for the electroplating operation, while the electroplating solution is continuously or periodically or otherwise pumped into the cooling cavities 16 to replenish the Pt available for electroplating and deposit a Pt layer having substantially uniform thickness on the selected surface area 20 of the internal wall W of each cooling cavity 16, while masking areas 21, 23 from being plated. The electroplating solution can flow through the cavities 16 and exit out of the cooling air exit passages 18 into the tank. The vane segment 5 is made the cathode by electrical cathode bus 33. For purposes of illustration and not limitation and to
During electroplating of each cooling cavities 16, the external airfoil surfaces of the vane segment 5 (between the masked shroud regions 10, 12) optionally can be electroplated with the noble metal (e.g. Pt, etc.) as well using other anodes 50 (partially shown in
Following electroplating and removal of the anode and its anode support from the vane segment, a diffusion aluminide coating is formed on the plated internal surface area 20 and the unplated internal surface areas 21, 23 by conventional gas phase aluminizing (e.g. CVD, above-the-pack, etc.), pack aluminizing, or any suitable aluminizing method. The diffusion aluminide coating formed on surface area 20 includes an amount of the noble metal (e.g. Pt) enrichment to improve its high temperature performance. That is, the diffusion aluminide coating will be enriched in Pt to provide a Pt-modified diffusion aluminide coating at surface area 20 where the Pt layer formerly resided,
Although the present invention has been described with respect to certain illustrative embodiments, those skilled in the art will appreciate that modifications and changes can be made therein within the scope of the invention as set forth in the appended claims.
1. A gas turbine engine airfoil component having an internal wall defining a cooling cavity within the component, the cooling cavity extending a length between a first end and a second end of the component, the internal wall having a first surface area extending along a first preponderant portion of the length of the cooling cavity and a second surface area extending along a second preponderant portion of the length of the cooling cavity, the first surface area having an electroplated metallic layer, the second surface area being un-plated by the electroplated metallic layer.
2. The component of claim 1 wherein the electroplated metallic layer is a noble metal.
3. The component of claim 1 wherein the component is a gas turbine engine blade or vane or segment of a blade or vane.
4. The component of claim 1 wherein the first surface area is aluminized.
5. The component of claim 1, further comprising cooling air exit passages extending through the wall and communicating with the cooling cavity.
6. The component of claim 5, wherein the cooling air exit passages are electroplated with a metallic layer.
7. The component of claim 6, wherein the cooling air exit passages are aluminized.
8. The component of claim 5, wherein the second surface area is disposed distal to the cooling air exit passages.
9. The component of claim 1, wherein the wall has a third surface area disposed at an angle relative to the first surface area and the second surface area, the third surface area lacking an electroplated metallic layer.
10. The component of claim 1, wherein the first surface area is disposed across the cooling cavity distal to the second surface area.
11. The component of claim 10, wherein the first surface area is disposed opposite to the second surface area.
12. The component of claim 1, wherein the first end of the cooling cavity is open and the second end of the of the cooling cavity is closed.
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Filed: Nov 30, 2017
Date of Patent: Aug 20, 2019
Patent Publication Number: 20180163547
Assignee: Howmet Corporation (Whitehall, MI)
Inventors: Willard N. Kirkendall (Muskegon, MI), Scott A. Meade (Muskegon, MI), Donald R. Clemens (North Muskegon, MI)
Primary Examiner: Joshua E Rodden
Application Number: 15/732,592
International Classification: C25D 5/02 (20060101); C25D 7/04 (20060101); F01D 5/28 (20060101); C25D 17/02 (20060101); F01D 5/12 (20060101); C25D 17/12 (20060101); F01D 5/18 (20060101); C25D 17/00 (20060101); C25D 5/48 (20060101); C25D 3/50 (20060101);