Patent Application
20200087794
The present disclosure relates to a method of using a multi-layer coating for dimensional restoration of a non-line of sight surface, more particularly to repairing a non-line of sight worn surface of a gas turbine engine component that is subjected to high operating temperatures.
Wear due to abrasion, fretting, galling, et cetera, often causes material loss beyond part blueprint dimensional limits. Besides wear, other mechanisms incurred during typical engine operation are also known to cause dimensional changes in parts that may lead to unserviceable conditions, such as for example, but not limited to: creep, oxidation, corrosion, etc. Many dimensional restoration processes exist, such as for example, plasma spray processing, welding, plating, etc. However, processes such as plasma spray processing are dependent on adequate “line-of-sight” in order to achieve a sufficient quality layer to restore part function by dimensional restoration. Line-of-sight is critical as it sets gun-to-part angles, allows accessibility by the equipment, et cetera. Welding also requires adequate line-of-sight to some degree to allow the welding torch and filler metal to access the worn features. However, welding may cause significant distortion of the part and/or a reduction of parent material properties to the point of being unusable (e.g., scrapped). Plating does not require line-of-sight, however, the most common electrolytic platings, such as nickel, suffer from softening and oxidation at temperatures above approximately 1000° F. (537.8° C.). However, temperatures up to approximately 1300° F. (704.4° C.) are expected for certain gas turbine engine components that have one or more non-line of sight surfaces requiring dimensional restoration. Thus, these high operating temperature requirements prevent conventional electrolytic nickel plating from being utilized to repair worn non-line of the sight surfaces. It is recognized that wear may not be the only cause for a part requiring dimensional restoration; other causes may include part growth due to creep mechanisms, part distortion, and/or excessive machining.
There is a need in the art for an improved process for dimensionally restoring a non-line of sight surface that is subject to high operating temperatures (i.e., greater than 1000° F. or 538° C.).
The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosure. The summary is not an extensive overview of the disclosure. It is neither intended to identify key or critical elements of the disclosure nor to delineate the scope of the disclosure. The following summary merely presents some concepts of the disclosure in a simplified form as a prelude to the description below.
Aspects of the disclosure are directed to a method of repairing a non-line of sight feature on a surface, the method comprising machining a worn irregular non-line of sight surface to provide a substantially planar repair surface, depositing an nickel plate base layer having a base layer thickness on the substantially planar repair surface, and depositing a protective layer having a protective layer thickness on the nickel plate base layer.
Depositing the protective layer may comprise depositing using vapor deposition.
Depositing using vapor deposition may comprise one of physical vapor deposition (PVD), electron-beam physical vapor deposition (EBPVD), or chemical vapor deposition (CVD).
Depositing the protective layer may comprise depositing MCrAlY.
Depositing the protective layer may comprise depositing a cobalt alloy.
Depositing the protective layer may comprise depositing the protective layer using at least one of a powder pack process, or locally applying at least one of paint, paste, slurry or thermal spray.
The protective layer may comprise an aluminide.
The protective layer may comprise a chromide.
The protective layer may have thickness of about 0.001 to 0.002 inches and the base layer thickness may be about 0.0005 to 0.002 inches.
Depositing the nickel plate base layer may comprise depositing an electrolytic nickel plate base layer.
Depositing the nickel plate base layer may comprise depositing an electroless nickel plate base layer
Aspects of the disclosure are also directed to a method of repairing a non-line of sight feature on a surface of a gas turbine engine component, the method comprising machining a worn irregular non-line of sight surface of the gas turbine engine component to provide a substantially planar repair surface, depositing a nickel plate base layer having a base layer thickness on the substantially planar repair surface, and depositing a protective layer having a protective layer thickness on the nickel plate base layer.
Depositing the protective layer may comprise one of physical vapor deposition (PVD), electron-beam physical vapor deposition (EBPVD), or chemical vapor deposition (CVD).
Depositing the protective layer may comprise depositing at least one of MCrAlY and cobalt alloy.
Depositing the protective layer may comprise applying at least one of a diffused aluminide and a diffused chromide.
Depositing the nickel plate base layer may comprise depositing an electrolytic nickel plate base layer.
Aspects of the disclosure are further directed to a method of repairing a feature on a surface, the method comprising machining a worn irregular sight surface to provide a substantially planar repair surface, depositing a nickel plate base layer having a base layer thickness on the substantially planar repair surface, and depositing a protective layer having a protective layer thickness on the nickel plate base layer.
The depositing using vapor deposition may comprise one of physical vapor deposition (PVD), electron-beam physical vapor deposition (EBPVD), or chemical vapor deposition (CVD).
The protective layer may comprise at least one of MCrAlY, cobalt alloy, diffused aluminide and diffused chromide.
Depositing the nickel plate base layer may comprise depositing an electrolytic nickel plate base layer.
As set forth above, because of the tight confines adjacent to a surface to be repaired, conventional techniques associated with the repair of line of sight surfaces cannot be used to repair the non-line of sight worn surface illustrated in
Referring to
However, such a nickel plate base layer is known to have poor oxidation and abrasion resistance, especially above 1000 deg. F. (538 deg. C.), which may lead to accelerated wear and possible spallation, liberating coating, et cetera.
Since the nickel plate base layer 408 may be exposed to nominal temperatures in excess of 1300 deg. F. (704 deg. C.) during operation of a gas turbine engine, the nickel plated base layer 408 would not provide the requisite life span. To protect the nickel plated base layer 408, a relatively thin protective layer may be applied. Referring to
The protective layer 410 may, for example, be diffused aluminide having a thickness of about 0.001-0.002 inches (0.0254-0.0508 mm). The protective layer 410 may be deposited using a powder pack process, vapor phase, or locally applied in the form of paint/paste/slurry/thermal spray. The protective layer 410 may also be deposited using vapor deposition processes, such as for example, physical vapor deposition (PVD) (e.g., CATARC® PVD), electron-bean physical vapor deposition (EBPVD), chemical vapor deposition(CVD), et cetera, to a thickness of about 0.0005-0.002 inches (0.0127-0.0508 mm). The protective layer 410 may also be a MCrAlY type coating deposited to a thickness of about 0.0005-0.002 inches (0.0127-0.0508 mm), including Stellite/cobalt coatings. The MCrAlY type protective coating may be deposited using vapor deposition. The sum of the nickel base layer thickness and the protective layer thickness may be equal to the original component thickness dimension in order provide the desired dimensional restoration.
To deposit the protective layer 410 on the non-line of sight/limited line of sight surface using vapor deposition, a skilled person will appreciate that the deposition process must ensure that the non-line of sight/limited line of sight surfaces to be coated are properly exposed to the vapor cloud in the deposition chamber. Examples of such techniques are disclosed in U.S. Pat. Nos. 8,541,069 and 9,885,110, which are assigned to the assignee of the present invention and hereby incorporated by reference.
Although the different non-limiting embodiments have specific illustrated components and/or steps, the embodiments are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.
It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.
The foregoing description is exemplary rather than defined by the features within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.
