Patent Application
20160090843
The present invention is directed toward a turbine component coating process and a turbine component. More specifically, the present invention is directed to masking for a turbine component coating process including multiple maskants and coatings, and a turbine component including multiple coatings.
Turbine components are often run at high temperatures to provide maximum operating efficiency. However, the temperature at which a turbine can run may be limited by the temperature capabilities of the individual turbine components. In order to increase the temperature capabilities of turbine components, various methods have been developed. One method for increasing the temperature capabilities of a turbine component includes the incorporation of internal cooling holes, through which cool air is forced during turbine engine operation. As cooling air is fed from the cooler side of the component wall through a cooling hole outlet on the hot side, the rushing air assists in lowering the temperature of the hot metal surface.
Another technique for increasing the temperature capabilities of a turbine component includes the application of coatings, such as a bond coat and a thermal barrier coating (TBC). Often, turbine components include both cooling holes and various coatings applied over the surface of the component. Typically, when cooling holes are formed or modified (e.g., repaired) in the component prior to the (re)application of the coatings, the cooling holes are either masked before coating or the coating is removed from the cooling holes after application. Current masking methods are often limited to applying a single masking material, then applying the one or more coatings to the component. The multiple coating applications may diminish the masking material, particularly when multiple application techniques are used, and thus may decrease the effectiveness of the masking process.
A turbine component coating process with improvements would be desirable in the art.
In one embodiment, a turbine component is disclosed. The turbine component includes at least one fluid flow passage at least one aperture disposed on a surface of the turbine component and fluidly connected to the at least one fluid flow passage. The at least one aperture includes a floor extending from the at least one fluid flow passage to the surface; and, a step disposed between an inner portion of the floor and an outer portion of the floor such that the inner portion of the floor and the outer portion of the floor do not comprise a single planar surface.
In another embodiment, a turbine component coating process is disclosed. The turbine component coating process includes applying a malleable masking material to one or more apertures of one or more fluid flow passages within a turbine component surface, and then applying a first coating over the malleable masking material and on the turbine component surface, wherein the malleable masking material causes at least a portion of the first coating to form a step in at least one of the one or more apertures of the one or more fluid flow passages. The turbine component coating process further includes then locally applying a local masking material to the one or more apertures of the one or more fluid flow passages, and then applying a second coating over the local masking material and on the first coating.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.
Provided are a turbine component coating process and a turbine component. Embodiments of the present disclosure, in comparison to articles and methods not using one or more of the features disclosed herein, increase aperture complexity, increase masking efficiency, increase masking effectiveness, increase masking specificity, decreases coating build-up in apertures, increases visibility for automated hole location, decreases volume of residual coating left after post process cooling hole clearing, decreases post-process hole clearing difficulty, or a combination thereof.
As illustrated in
Suitable components 100 for the disclosed embodiments include, for example, blades or buckets; shrouds; nozzles; vanes; transition pieces; liners; combustors; transition pieces; other components having apertures, such as cooling holes; or combinations thereof. The turbine components 100 may be fabricated from high temperature oxidation and corrosion resistant materials, including, for example, nickel-based superalloys, cobalt-based superalloys, gamma prime superalloys, stainless steels, or combinations thereof. In some embodiments, the turbine nozzle, or other turbine component, may include a coating applied over the surface 103. The coating may be a single layer, more than one layer, or a plurality of layers. Suitable coatings can include, but are not limited to, a bond coat, a thermal barrier coating (TBC), an environmental barrier coating (EBC), or combinations thereof.
Referring to
Specifically, the combination of the malleable masking material 201 and the local masking material 205 may decrease or eliminate deposition of the first and/or second coating 203 and 207 and/or any additional coatings in the one or more apertures 105, while further facilitating a less labor intensive process by allowing for broad masking applications where possible. Furthermore, in some embodiments, the malleable masking material 201 may facilitate a limited deposition of coating material 203 and 207 within the aperture 105 to form a step 115 to disrupt fluid flow 109 exiting the fluid flow passage 104 (illustrated in
Still referring to
In some embodiments, the malleable masking material 201 is therefore selected based upon a composition and/or the application method of the first coating 203. In some embodiments, the malleable masking material 201 is selected to control the diminishment of the maskant throughout application of a subsequent coating layer. As used herein, “diminishment” refers to decreasing a level of the maskant with respect to the surface 103, such as through degrading, removing, shrinking, and/or recessing the maskant within the aperture 105. In even some embodiments, the malleable masking material 201 is selected based upon a method of application of the maskant to decrease or eliminate contamination and/or damage (e.g., chipping during excess maskant removal) of an applied coating.
Suitable materials for the malleable masking material 201 can include, but are not limited to, a silicone elastomer, an epoxy, a ductile material, or combinations thereof. In some particular embodiments, the malleable masking material 201 includes a material having ductile properties that provide resistance (i.e., decrease or eliminate diminishment from) to the HVOF spray process, such as the silicone elastomer. In some embodiments, the silicone elastomer can include any elastomer suitable for resisting grit blasting and/or high velocity particles. One such exemplary suitable silicone elastomer is commercially available as MachBloc and comprises a ductile (e.g., rubbery, putty-like) material having a medium temperature melting point/boiling point and a composition of, by weight, between about 20% and about 30% methyl vinyl/dimethyl vinyl/vinyl terminated siloxane, between about 20% and about 30% vinyl silicone fluid, between about 15% and about 30% ground silica, between about 15% and about 25% silicon dioxide, between about 3% and about 9% silanol terminated PDMS, up to about 0.5% sodium alumino sulphosilicate, up to about 1% vinyl-tris(2-methoxy ehoxy)silane, up to about 1% titanium dioxide, up to about 2% precipitated silica, up to about 1% stoddard solvent, up to about 0.5% neodecanoic acid, rare earth salts, up to about 0.5% rare earth 2-ethylhexanoate, and up to about 0.2% magnesium ferrite.
The malleable masking material 201 may be applied to the component 100 in step 210 in any amount and/or thickness sufficient to at least partially cover at least one aperture 105. For example, the malleable masking material 201 may be slightly below level with, level with, substantially level with, or form a protrusion extending above, the surface 103. In one embodiment, the malleable masking material 201 is applied to the surface 103 to a broad area of the turbine component surface 103 that comprises one or more apertures 105 of fluid flow passages 104. For example, the malleable masking material 201 may be applied via a roller application over a broad surface area.
In some embodiments, the malleable masking material 201 is removed from the surface 103 in step 215 prior to the applying of the first coating 203 in step 220. Such removal can re-expose the surface 103 of the turbine component 100 while leaving the one or more apertures 105 masked. For example, in some embodiments, removal may be performed by grit blasting or the like. As discussed above, such embodiments may actually push the malleable masking material 201 further into the aperture 105 such that it sits below the surface 103 of the component 100. It should be noted that in a further embodiment, the applying of the first coating 203 in step 220 may alternatively or additionally recesses the malleable masking material 201 into the one or more apertures 105.
However, in some embodiments, removal may result in masked apertures wherein the malleable masking material is substantially level with, or even protruding from, the surface 103 of the component 100. In even some embodiments, the malleable masking material 201 may be applied only to the one or more apertures 105, reducing or eliminating deposition and/or subsequent removal of the malleable masking material 201 from the surface 103.
Still referring to
In some particular embodiments, the first coating 203 may be applied through any kinetic energy process (e.g., HVOF). The force of the first coating 203 striking the malleable masking material 201 through the kinetic energy process may start or continue to depress the malleable masking material 201 within at least one of the one or more apertures 105 such that the malleable masking material 201 sits below the surface 103 of the component 100. In other embodiments, the first coating 203 may be applied through any other suitable process such as thermal spray, air plasma spray (APS), high velocity air fuel spraying (HVAF), vacuum plasma spray (VPS), electron-beam physical vapor deposition (EBPVD), chemical vapor deposition (CVD), ion plasma deposition (IPD), combustion spraying with powder or rod, cold spray, sol gel, electrophoretic deposition, tape casting, polymer derived ceramic coating, slurry coating, dip-application, vacuum-coating application, curtain-coating application, brush-application, roll-coat application, agglomeration and sintering followed by spray drying, or a combination thereof.
As discussed above, in some embodiments, the malleable masking material 201 may cause at least a portion of the first coating 203 to form a step (element 115 in
Still referring to
The local masking material 205 can comprise any material that is suitable for local application on or within the one or more apertures 105 while further inhibiting or preventing bonding with the subsequent first coating 203. In some embodiments, the local masking material 205 is there selected based upon a composition and/or the application method of the second coating 207. In some embodiments, the local masking material 205 is selected to decrease or eliminate diminishment of the maskant throughout application of a subsequent coating layer. As used herein, “diminishment” refers to decreasing a level of the maskant with respect to the surface 103, such as through degrading, removing, shrinking, and/or recessing the maskant within the aperture 105. In even some embodiments, the local masking material 205 is selected based upon a method of application of the maskant to decrease or eliminate contamination and/or damage (e.g., chipping during excess maskant removal) of an applied coating.
Suitable materials for the local masking material 205 can include, but are not limited to an ultraviolet (UV)-curable material, an electron beam (EB)-curable material, an epoxy, a brittle material, or combinations thereof. In some embodiments, the local masking material 205 includes a material having brittle properties that provide resistance to high temperatures present in the APS process, such as the UV-curable material. In some embodiments, the UV-curable material and/or the EB-curable material includes any material suitable for flowing through a syringe and/or resisting high temperatures of, for example, at least 500° F., at least 600° F., at least 700° F., at least 800° F., between 500° F. and 800° F., or any combination, sub-combination, range, or sub-range thereof. In a further embodiment, the UV-curable material may be devoid or substantially devoid of thermal-curing properties at a select temperature, for example, of up to 800° F. One such suitable material is a high temperature melting point/boiling point epoxy, such as, but not limited to, acrylated urethane. The high temperature melting point/boiling point includes, for example, a temperature of at least 1,200° F., at which the epoxy is incinerated.
The local masking material 205 may be locally applied to the one or more apertures 105 in step 230 in any amount and/or thickness sufficient to cover the malleable masking material 201 and/or any unmasked portions of the at least one aperture 105. In some embodiments, the local masking material 205 is locally applied over the malleable masking material 201 and/or in portions of the at least one aperture 105 exposed by the recessing of the malleable masking material 201. In some embodiments, the malleable masking material 201 is removed from the at least one aperture 105 prior to the local applying of the local masking material 205 in step 230. The local masking material 205 may be slightly below level with, level with, substantially level with, or form a protrusion extending above, the surface 103 and/or the first coating 203. Suitable methods of application of the local masking material 205 include manual application with a syringe, automated application with a syringe, using a paint-brush, using a finger, extruding the local masking material 205 through the at least one aperture 105 from a region distal from the surface 103, or combinations thereof.
Still referring to
The second coating 207, and/or any additional coatings may be applied by any suitable application method. Suitable application methods include, but are not limited to, thermal spray, air plasma spray (APS), high velocity oxygen fuel (HVOF) thermal spray, high velocity air fuel spraying (HVAF), vacuum plasma spray (VPS), electron-beam physical vapor deposition (EBPVD), chemical vapor deposition (CVD), ion plasma deposition (IPD), combustion spraying with powder or rod, cold spray, sol gel, electrophoretic deposition, tape casting, polymer derived ceramic coating, slurry coating, dip-application, vacuum-coating application, curtain-coating application, brush-application, roll-coat application, agglomeration and sintering followed by spray drying, or combinations thereof. In one example, the second coating 207 includes the bond coat and/or thermal barrier coating applied by the APS as discussed above.
After applying the second coating 207 and/or any other additional coatings, the local masking material 205 (and any remaining malleable masking material 201) may optionally be removed in step 250. In some embodiments, the malleable masking material 201 and/or the local masking material 205 can be removed by a heating operation such that the masking materials melt away from the turbine component. In some embodiments, the malleable masking material 201 and/or the local masking material 205 can be removed by water jet, manual clearing, or combinations thereof.
In some embodiments, the local masking material 205 decreases adhesion of the second coating 207, providing effective cleaning of the at least one aperture 105 through water jet or manual clearing. In some embodiments, removing the local masking material 205 includes exposing the local masking material 205 to a temperature above the boiling temperature for the local masking material 205. In some embodiments, the exposing of the local masking material 205 to a temperature above the boiling temperature melts the local masking material 205, causing the local masking material 205 to run out through the at least one aperture 105. Exposing the local masking material 205 to a temperature above the boiling temperature (i.e., a heating operation) includes, for example, positioning the component 100 in a furnace, placing the component 100 in operation under operating temperatures that exceed the boiling temperature, or locally heating the local masking material 205 (e.g., focused laser beam).
In even some embodiments, the turbine component coating process 200 includes removing an existing coating from the surface 103 of the component 100 prior to the applying of the malleable masking material 201 (step 210). The existing coating includes any existing coating, such as, but not limited to, an operationally-used coating, a damaged coating, or a defective coating. For example, the coating process 200 may include removing the operationally-used coating to replace the existing coating with a new coating, to repair the component 100, to inspect the component 100, during maintenance of the component 100, or a combination thereof. In one embodiment, at least a portion of the existing coating is removed manually, with a chemical solution, or a combination thereof.
Referring now to
The aperture 105 (e.g., cooling hole) can further comprise a variety of configurations. For example, the aperture 105 may comprise a cross-sectional geometry, wherein the cross-sectional geometry may include a constant cross-sectional geometry, a varied cross-sectional geometry, a diffuser cross-sectional geometry (as illustrated in
The at least one aperture 105 may generally comprise a floor 110 for which guides the bottom of the fluid flow 109 as it exits the component 100. Depending on the specific configuration of the fluid flow passage 104 and aperture 105, one or more side walls 117 and/or a ceiling 119 may further bound the exiting fluid flow 109. In even some embodiments, the ceiling 119 and or the side walls 117 may comprise a taper 120 towards the surface 103. In such embodiments, the taper comprise a height of from about 0.0 inches (e.g., a sharp edge) to about 0.045 inches or greater depending, for example, on the manufacturing method.
The aperture 105 further comprises a step 115 disposed on the floor 110. The step 115 may be produced, for example, using the turbine component coating processes disclosed herein. However, it should also be appreciated that the step 115, the fluid flow passage 104 and/or the aperture 105 may additionally or alternatively be produced using any other suitable method such as, for example, additive manufacturing, casting, water-jet machining, electrical discharge machining, welding, or one or more other coating processes or combinations thereof. As best illustrated in
Specifically, the step 115 may be disposed between an inner portion 111 of the floor 110 and an outer portion 112 of the floor 110 such that the inner portion 111 and the outer portion 112 do not comprise a single planar surface. In some embodiments, the step 115 may comprise bump, ridge, plane or the like. The step 115 may meet with the inner and outer portions 111 and 112 at distinct points, or may meet at curved radii.
In some particular embodiments, the step 115 may extend for an entire length L between two opposing side walls 117. In other embodiments, the step 115 may extend for only a portion of the length L between two opposing side walls 117. In even some embodiments, the step 115 may comprise one or more gaps along its length. Moreover, in some embodiments, the step 115 may extend in a direction substantially perpendicular to the direction of fluid flow 109 (as illustrated in
As best illustrated in
While the step 115 may be utilized in a variety of aperture 105 and fluid flow passage 104 configurations, the step 115 may be particularly suited for diffuser configurations. For example, in some embodiments, such as that illustrated in
While the invention has been described with reference to one or more embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. In addition, all numerical values identified in the detailed description shall be interpreted as though the precise and approximate values are both expressly identified.
