阅读说明：本技术 清洁具有热障涂层的部件的方法 (Method for cleaning a component having a thermal barrier coating ) 是由 罗伯特·舍尔 马哈茂德·K·西利提 拉斐尔·A·德卡德纳斯 于 2018-09-20 设计创作，主要内容包括：一种清洁部件的方法,该方法包括：提供在部件于高温环境中操作之后的部件,该部件包括热障涂层(TBC)；使用海绵射流喷砂过程清洁部件的TBC；以及测量TBC的清洁过的厚度,以验证清洁过的厚度是否超过将允许部件返回至高温环境的预定最小值。(A method of cleaning a component, the method comprising: providing a component after the component is operated in a high temperature environment, the component comprising a Thermal Barrier Coating (TBC); cleaning the TBC of the component using a sponge jet blasting process; and measuring the cleaned thickness of the TBC to verify whether the cleaned thickness exceeds a predetermined minimum value that will allow the component to return to a high temperature environment.)

1. A method of cleaning a component, the method comprising:

providing a component after the component is operated in a high temperature environment, the component comprising a Thermal Barrier Coating (TBC);

cleaning the TBC of the component using a sponge jet blasting process; and

measuring a cleaned thickness of the TBC to verify whether the cleaned thickness exceeds a predetermined minimum value that will allow the component to return to the high temperature environment.

2. The method of claim 1, wherein the component comprises a blade from a gas turbine.

3. The method of claim 1, further comprising selecting a feed pressure for the sponge jet blasting process.

4. The method of claim 1, further comprising measuring a starting thickness of the TBC to verify whether the starting thickness is greater than a predetermined threshold.

5. The method of claim 4, further comprising comparing the starting thickness to the cleaned thickness to determine a removal thickness of the TBC.

6. The method of claim 5, wherein the removal thickness is less than 0.001 inches (0.025 mm).

7. The method of claim 1, further comprising applying once and only once APS spray/coat.

8. The method of claim 1, wherein the component comprises one of a transition portion, a basket portion, and a support housing.

9. A method of cleaning a component, the method comprising:

providing a component that has been operated in a high temperature environment, the component comprising a Thermal Barrier Coating (TBC);

measuring a first thickness of the TBC to verify whether the first thickness is greater than a predetermined threshold;

selecting operating parameters of a sponge jet flow sand blasting process;

cleaning the TBC of the component using the sponge jet blasting process; and

measuring a second thickness of the TBC to determine an amount of TBC removal during cleaning and to verify whether the thickness exceeds a predetermined minimum value that will allow the component to return to the high temperature environment.

10. The method of claim 9, wherein the component comprises one of a transition portion, a basket portion, and a support housing.

11. The method of claim 9, wherein the component comprises a blade from a gas turbine.

12. The method of claim 9, wherein the operating parameter is a feed pressure for a sponge jet blasting process.

13. The method of claim 9, wherein the removal of the TBC is less than 0.001 inches (0.025 mm).

14. The method of claim 9, further comprising applying one APS spray/coating to the part.

15. The method of claim 9, further comprising applying a second APS spray/coating to the component.

16. The method of claim 9, further comprising measuring the first thickness and the second thickness using an eddy current process.

Technical Field

The present disclosure relates generally to methods of refurbishing high temperature components, and more particularly to refurbishing high temperature components that include a Thermal Barrier Coating (TBC).

Background

To increase the efficiency of gas turbine engines, increasingly higher operating temperatures have been used. Higher temperatures require advances in materials including more commonly used TBCs. Components exposed to hot combustion gases may include TBC to protect the components from high temperatures and corrosive elements within the combustion gases. Typically, TBCs comprise ceramic materials that can be easily damaged during operation. Additionally, TBC's are typically replaced periodically to ensure that a sufficient TBC thickness is maintained during operation.

Disclosure of Invention

A method of cleaning a component, the method comprising: providing a component after the component is operated in a high temperature environment, the component comprising a Thermal Barrier Coating (TBC); cleaning the TBC of the component using a sponge jet blasting process; and measuring the cleaned thickness of the TBC to verify whether the cleaned thickness exceeds a predetermined minimum value that will allow the component to return to a high temperature environment.

In another configuration, a method of cleaning a component includes: providing a component that has been operated in a high temperature environment, the component comprising a Thermal Barrier Coating (TBC); measuring a first thickness of the TBC to verify that the first thickness is greater than a predetermined threshold; and selecting operating parameters of the sponge jet blasting process. The method also includes cleaning the TBC of the component using a sponge jet blasting process, and measuring a second thickness of the TBC to determine an amount of TBC to remove during the cleaning, and to verify whether the thickness exceeds a predetermined minimum value that will allow the component to return to a high temperature environment.

The foregoing has outlined rather broadly the features of the present disclosure so that those skilled in the art may better understand the detailed description that follows. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims. Those skilled in the art will appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Those skilled in the art will also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure in its broadest form.

In addition, before the following detailed description is presented, it is to be understood that various definitions of certain words and phrases are provided throughout this specification, and that it will be understood by one of ordinary skill in the art that in many, if not most instances, these definitions apply to prior, as well as future uses of such defined words and phrases. Although some terms may include a wide variety of embodiments, the appended claims may expressly limit these terms to particular embodiments.

Drawings

FIG. 1 is a flow chart illustrating a process of repairing or refurbishing a component that includes a Thermal Barrier Coating (TBC).

FIG. 2 is a schematic view of a sponge jet system suitable for cleaning TBC on components.

FIG. 3 is a graph illustrating an example of cleaned turbine blades and TBC thickness variation.

FIG. 4 is an image of a portion of a turbine blade prior to a cleaning process.

FIG. 5 is an image of a portion of a turbine blade after a cleaning process.

FIG. 6 is a schematic cross-sectional view of a surface of a component including a TBC.

FIG. 7 is a cross-sectional view of a gas turbine including blades, vanes, baskets, transitions, and other components including a TBC.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

Detailed Description

Various technologies pertaining to systems and methods will now be described with reference to the drawings, wherein like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged device. It should be understood that functions described as being performed by certain system elements may be performed by multiple elements. Similarly, for example, an element may be configured to perform a function described as being performed by a plurality of elements. The numerous innovative teachings of the present application will be described with reference to exemplary, non-limiting embodiments.

In addition, it is to be understood that the words or phrases used herein are to be interpreted broadly, unless expressly limited in some instances. For example, the terms "including," "having," and "including," as well as derivatives thereof, mean including, but not limited to. The singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, as used herein, the term "and/or" refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term "or" is inclusive, meaning and/or, unless the context clearly dictates otherwise. The phrases "associated with … …" and "associated therewith" and derivatives thereof may refer to include, included within, interconnected with … …, contained within, connected to or with … …, coupled to or with … …, capable of connecting with … …, cooperating with … …, staggered, juxtaposed, adjacent, bonded to or combined with … …, having the characteristics of … …, and the like.

In addition, although the terms "first," "second," "third," etc. may be used herein to refer to various elements, information, functions, or actions, these elements, information, functions, or actions should not be limited by these terms. Rather, these adjectives are used to distinguish one element, information, function, or action from another. For example, a first element, a first information, a first function, or a first action may be termed a second element, a second information, a second function, or a second action, and, similarly, a second element, a second information, a second function, or a second action may also be termed a first element, a first information, a first function, or a first action, without departing from the scope of the present disclosure.

Additionally, unless the context clearly indicates otherwise, the term "adjacent to" may mean: an element is relatively close to but not in contact with another element; or the element is in contact with another part. Further, the phrase "based on" is intended to mean "based, at least in part, on" unless explicitly stated otherwise. The term "about" or "substantially" or similar terms are intended to encompass variations in value that are within normal industry manufacturing tolerances for that dimension. Unless otherwise indicated, a 20% variation would fall within the meaning of these terms if no industry standard were available.

The gas turbine 10, and in particular a large gas turbine for use in power generation (fig. 7), includes a combustion section and a turbine section that operate at extremely high temperatures. To protect the components from high temperatures and corrosion due to exposure to elements in the combustion gases, many components include a thermal barrier coating 15 (referred to herein as a "TBC"). As schematically illustrated in FIG. 6, rather than to scale, TBC 15 is a thin layer of material applied to the exposed surface of the component. Typically, the TBC 15 is applied to the bond coat 20, and the bond coat 20 is applied directly to the substrate 25 or the surface of the component protected by the TBC 15. The bond coat 20 is selected to provide the desired bond with the substrate 25, but also to provide sufficient bonding of the TBC 15. In some configurations, as illustrated in FIG. 6, a thermally grown oxide layer 30 is formed between bond coat 20 and TBC 15 to improve the bonding of TBC 15. The selection of materials for bond coat 20 and oxide layer 30, if employed, is not critical to the present invention, and the selection of materials for bond coat 20 and oxide layer 30 is selected based on design considerations, such as the materials used for substrate 25, the difference in thermal expansion coefficients between substrate 25 and TBC 15, and other considerations not critical to the present invention.

In most configurations, TBC 15 is a ceramic material, such as yttria stabilized zirconia. In some configurations, TBC 15 comprises a pyrochlore-based ceramic or zirconia-based TBC with yttria-stabilized zirconia (e.g., 8YSZ) well suited for the present application. Typical applications of TBC 15 utilize an atmospheric plasma spray process (APS) that creates a bond line 35 between the TBC 15 and the material layer (bond coat 20) to which the TBC 15 is applied. Of course, other TBC's 15 may be employed as desired.

After a predetermined period of operation of the gas turbine engine 10, many components require periodic maintenance and inspection. One example of such components are various turbine blades 40 (rotating) located within the turbine section of engine 10. Other components may include the buckets 45 (stationary), basket 50, transition 55, or any other component that includes the TBC 15 (as shown in fig. 7). As one of ordinary skill will appreciate, the processes described herein may be applied to any of these components, including the TBC 15. The remaining description focuses on the repair/refurbishment of the blade 40, but it is obvious that the invention should not be limited to the blade 40 as a component.

FIG. 1 is a flow chart summarizing the basic process for repairing/refurbishing turbine blades 40 after operating at an elevated operating temperature for a predetermined period of time. Referring to fig. 1, the initial step in the process is to remove 60 the blade from service. Each blade 40 is repaired or refurbished independently and therefore must be removed from the turbine rotor to allow independent processes to be applied when necessary.

Next, each blade 40 is inspected using various non-destructive inspection (NDE) techniques. One inspection is an inspection 65 of the thickness 67 of the TBC 15 at various locations on each blade 40. While several different techniques may be used to perform such inspection 65, eddy current inspection is preferred. Eddy current inspection can easily detect the knit line 35 between the TBC 15 and the bond coat 20 to which the TBC 15 is attached to measure the thickness 67 of the TBC 15. FIG. 3 includes a table 70 of three blades 40 for inspection at 12 different locations. The data includes the loss of TBC layer 15 in thickness 67 (in microns) due to repair or refurbishment at different locations.

Once the thickness 67 of the TBC 15 is measured, an analysis 75 is performed to ensure that sufficient TBC 15 will remain after the repair/refurbishment process for continued operation for the next scheduled inspection and repair. For example, a component may require a minimum TBC thickness 67 of 12 microns or greater before the process can be performed. If any of the measured thicknesses 67 are below the minimum thickness 67, the TBC 15 must be stripped and reapplied (step 140) before the blade 40 or other component can be placed back in service. For the blade 40 recorded in the table of fig. 3, all measured positions exceed the minimum TBC thickness 67, thereby making the blade 40 suitable for a repair/refurbishment process.

The next step in the repair/refurbishment process is to sponge blast 80 the blade 40, and in particular the area including the TBC 15. In previous repairs, grit blasting was used to completely remove the TBC 15 to allow the TBC 15 to be reapplied. However, it has been found through significant testing and experimentation that if appropriate parameters are employed, the sponge blasting process can be used to clean the blade 40 or other components without the need to remove excessive TBC 15.

Fig. 2 illustrates a sponge blasting device 85, the device 85 comprising a primary feed unit 90, the primary feed unit 90 providing the required medium 95 to an air flow 100 at a required rate. The air may be provided by a separate air compressor or other source and the air compressor or other source is adjusted to provide air at the desired operating pressure. The user 105 operates a nozzle or gun 110, which nozzle or gun 110 directs air and media at the surface to be cleaned. The nozzle or gun 110 also regulates the air to maintain the desired feed pressure. A retriever 115 may be provided to collect the used media 95 and redirect the used media 95 to the feeding unit 90 for reuse. The retriever 115 separates the still usable media 95 from media 95 that is damaged or degraded to the extent that it cannot be reused. Additional components may be employed as desired to enhance the sponge blasting system 85.

During sponge blasting, air 100 at operating pressure will mix with blasting media 95 as both air 100 and media 95 are directed at the part at the feed pressure. The selection of operating pressure, media 95, and feed pressure each affect the quality of the cleaning process and the amount of TBC 15 removed. In one arrangement, the operating pressure is between 35psi and 55psi, with about 45psi plus or minus 5psi more preferred, and the feed pressure is between 20psi and 40psi, with about 30psi plus or minus 5psi preferred.

While many media 95 may be used in the sponge blasting process, one media 95 that has been found particularly suitable is a sponge substrate impregnated with alumina having a particle size between 200 and 400, and more preferably between 300 and 350. More abrasive or corrosive media or less corrosive media may also be used. It should be noted that the aforementioned 200 to 400 particle size alumina media works well at the above-mentioned defined pressures. If a different medium is selected, it may also be necessary to adjust the aforementioned pressure.

Fig. 4 illustrates the turbine blade 40 prior to the sponge blasting step 80 (fig. 1), and fig. 5 illustrates the turbine blade 40 after the sponge blasting step 80. After the sponge blasting step 80, 120 will again measure the thickness 67 of the TBC. Table 70 in fig. 3 includes the results of this second measurement 120 and shows the amount of TBC 15 removed during this process. Additionally, a second predetermined minimum thickness may be set at this stage of the process such that any blade 40 having a thickness 67 below the minimum thickness is further repaired by stripping away TBC layer 15 and reapplying TBC layer 15 as has been done in the past (see analysis step 125 in FIG. 1). In this example, none of blades 40 have a thickness 67 below this second predetermined minimum thickness so that all of blades 40 may proceed to the next step in the process.

As is known, many turbine blades 40 and vanes 45 or other components include internal passages and holes formed in the surfaces of the turbine blades 40 and vanes 45 or other components to allow cooling air to flow through the blades 40 or vanes 45. During the sponge blasting step 80, it is likely that some of the media 95 will become lodged in the surface pores and/or within the internal passages. To remove these unwanted residues, the blade 40 is heated to a predetermined temperature for a period of time (step 130). As discussed, the preferred sponge blasting media 95 comprises alumina embedded in a sponge matrix. The predetermined temperature is selected to ensure complete combustion of the sponge material so that all that remains is alumina material. The particle size of the alumina is small enough that the alumina can be removed by flushing the channels with high pressure air, water, or other fluids as may be required. In one configuration, the blade 40 and vane 45 are heated to about 1000 to 1200 degrees Fahrenheit (538 to 649 degrees Celsius) plus or minus 20 percent for about one hour. Other applications require higher or lower temperatures and longer or shorter holding times. In addition, in most applications it is desirable to heat the components slowly, as rapid heating may create thermal stress and may result in damage or distortion of the components.

In the next step, the blade 40 or other component will be subjected to an Atmospheric Plasma Spray (APS) coating process 135 to improve the uniformity of the TBC 15 surface. Once this coating step 135 is completed, the blade 40 or other component may be cleaned to remove any debris or overspray, any internal passages may be cleaned, and the blade 40 or other component may be subjected to additional analysis, inspection, or testing and then returned to service.

Although exemplary embodiments of the present disclosure have been described in detail, those skilled in the art will appreciate that various modifications, equivalents, variations and improvements disclosed herein may be made without departing from the spirit and scope of the present disclosure in its broadest form.

None of the description in this application should be read as implying that any particular element, step, action, or function is an essential element which must be included in the claim scope: the scope of patented subject matter is defined only by the allowed claims. Furthermore, none of these claims are intended to recite an apparatus plus function claim structure unless the precise word "method of … …" is followed by a word separator.