Abstract:
A method of coating a corner interface of a turbine system includes placing a mesh assembly proximate the corner interface. The method also includes depositing a coating onto and through the mesh assembly and into the corner interface, wherein the mesh assembly dampens a kinetic energy of the coating and secures the coating proximate the corner interface.

Description:
FEDERAL RESEARCH STATEMENT 
       [0001]    This application was made with U.S. Government support under Agreement No. DE-FC26-05NT42643 awarded by the Department of Energy. The U.S. Government may have certain rights in this invention. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The subject matter disclosed herein relates to gas turbine systems, and more particularly to a method of coating components within gas turbine systems. 
         [0003]    Typically, in turbine systems, components associated with rotating machinery such as compressors and turbines, for example, are subjected to a sustained high temperature, high load environment. Many of the components are coated for thermal or oxidative protection, with the coating process being a particulate aerosol or plasma spray comprising particles. During the coating process, the particles of the coating approach a surface of the component to be coated and the specific type of interaction of the particles with the surface depends on several factors, such as particle size, particle velocity, particle hardness, particle temperature, surface impingement angle, and the presence of sharp corners at the intersections of adjacent surfaces. 
         [0004]    Often, when particles are applied into a corner joint, the particles will not adhere to the surface in a satisfactory manner, based on high particle energy and a ricocheting and/or reflecting of the particles. This prevents a proper buildup of the coating. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    According to one aspect of the invention, a method of coating a corner interface of a turbine system includes placing a mesh assembly proximate the corner interface. The method also includes depositing a coating onto and through the mesh assembly and into the corner interface, wherein the mesh assembly dampens a kinetic energy of the coating and secures the coating proximate the corner interface. 
         [0006]    According to another aspect of the invention, a method of coating a corner interface of a turbine component includes placing a mesh assembly proximate the corner interface, wherein the mesh assembly is removable. Also included is depositing a coating onto and through the mesh assembly and into the corner interface, wherein the mesh assembly dampens a kinetic energy of the coating and secures the coating proximate the corner interface. Further included is removing the mesh assembly from proximate the corner interface. 
         [0007]    According to yet another aspect of the invention, a method of coating a corner interface of a turbine component includes placing a mesh assembly proximate the corner interface. Also included is depositing a coating onto and through the mesh assembly and into the corner interface, wherein the mesh assembly dampens a kinetic energy of the coating and secures the coating proximate the corner interface, wherein the mesh assembly comprises a material that is consumable within the coating. 
         [0008]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0009]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0010]      FIG. 1  is a front perspective view of a turbine airfoil being coated at a corner interface through a mesh assembly; 
           [0011]      FIG. 2  is a side elevational view of an inner corner having a plurality of mesh assemblies therein; 
           [0012]      FIG. 3  is a side elevational view of the inner corner having a split mesh assembly; 
           [0013]      FIG. 4  is a side elevational view of the inner corner having a removable mesh assembly placed therein; 
           [0014]      FIG. 5  is a side elevational view of the inner corner having a first coating layer disposed between the inner corner and the removable mesh assembly; 
           [0015]      FIG. 6  is a side elevational view of the inner corner having the removable mesh assembly spaced outwardly from the first coating layer; 
           [0016]      FIG. 7  is a side elevational view of the inner corner having a second coating layer disposed between the first coating layer and the removable mesh assembly; 
           [0017]      FIG. 8  is a side elevational view of the inner corner having the first coating layer and the second coating layer disposed therein after the removable mesh assembly has been removed; 
           [0018]      FIG. 9  is a front perspective view of an outer corner having the mesh assembly placed thereon; 
           [0019]      FIG. 10  is a side elevational view of the outer corner having a continuous mesh; and 
           [0020]      FIG. 11  is a side elevational view of the outer corner having a split mesh. 
       
    
    
       [0021]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Referring to  FIG. 1 , an airfoil, or a first surface  10  of a turbine bucket is illustrated and intersects with a second surface  12  that is substantially perpendicular to the first surface  10 . The intersection is generally referred to as a corner interface  14 . A coating  16  is deposited proximate the corner interface  14  and may be applied in the form of a spray, for example. The coating  16  comprises a plurality of particles, including but not limited to plasma. Embodiments of the present invention are not limited to any particular type of spray device. Some non-limiting examples of thermal spray methods include direct current (DC) plasma spray, vacuum plasma spray, suspension plasma spray (SPS), wire-arc spray, combustion/flame spray or high-velocity oxygen fuel thermal spray process (HVOF). To efficiently coat the corner interface  14  with the coating  16 , a mesh assembly  18  is disposed proximate the corner interface  14  prior to depositing the coating  16 . The mesh assembly  18  functions as a dampening element, with respect to a kinetic energy possessed by particles of the coating  16 . Dampening of the kinetic energy reduces the tendency of the particles from ricocheting or deflecting away from the corner interface  14 , thereby resulting in stabilization of the particles as they are deposited and retention of the particles proximate the corner interface  14 , as a result of a more uniform energy distribution. 
         [0023]    The mesh assembly  18  may be formed of various materials and includes a plurality of apertures  20 . The density of the apertures  20  is dependent upon the particular application, and factors such as composition of the coating  16  and material of the corner interface  14  will influence how fine the mesh assembly  18  should be. The mesh assembly  18  may be removable or consumable, as will be described in detail below. Whether the mesh assembly  18  is removable or consumable will influence what material is employed for the mesh assembly  18 . Such materials include, but are not limited to, woven or braided materials formed from ceramics such as Silicon Carbide (SiC) ceramic oxides including, but not limited to, those oxides of Aluminum, Silicon, and Boron, various carbon based materials, polymers and metallic alloys. As with the density of the mesh assembly  18 , the suitable material of the mesh assembly  18  will depend upon composition of the coating  16  and material of the corner interface  14 , but also upon whether the mesh assembly  18  is to be removable from the coating  16  or consumable within the coating  16 . The mesh assembly  18  may be attached to the corner interface  14  in a variety of ways, including bonding or tacking the edges of the mesh assembly  18  to the corner interface  14 , for example. 
         [0024]    Referring now to  FIGS. 2 and 3 , the corner interface  14  is shown as an inner corner  22  arrangement, where the first surface  10  and the second surface  12  define an angle therebetween. The angle between the first surface  10  and the second surface  12  is approximately 90 degrees, but it should be appreciated that numerous other angles are appropriate for use with the embodiments disclosed herein. The corner interface  14  may include more than one mesh assembly  18  ( FIG. 2 ). A plurality of mesh assemblies may be advantageous for a number or reasons, such as a desire to form a multi-layered coating  16 , for example. In the illustrated example, a first mesh  24  and a second mesh  26  are shown. A first coating layer may be deposited into the corner interface  14  and disposed between the corner interface  14  and the first mesh  24 . A second coating layer is then deposited through the second mesh  26  and is therefore disposed between the first coating layer and the second mesh  26 . A first mesh  24  and a second mesh  26  have been shown as an example and it is contemplated that any number of meshes may be employed to provide an ability to produce multiple coating layers. The coating layers may be of the same or a distinct composition and may include gaps between them, depending on the mesh assembly  18 . Additional coating  16  features and advantages may be achieved by employing a split mesh assembly  28  ( FIG. 3 ), where a portion of the split mesh assembly  28  comprises a gap that allows the coating  16  to more freely enter the corner interface  14 , but still retains the coating  16  by positioning of the split mesh assembly  28 . 
         [0025]    Referring to  FIGS. 4-8 , a method of depositing the coating  16  is illustrated. As described above, the first mesh  24  may be removable. By removable, it should be appreciated that the first mesh  24  is positioned and attached proximate the corner interface  14  ( FIG. 4 ) prior to depositing of the coating  16 . The coating  16  is then deposited toward and through the first mesh  24  until a first coating layer  30  has been formed ( FIG. 5 ). The first mesh  24  is then removed and the second mesh  26 , which is larger than the first mesh  24  in the illustrated example, is positioned and attached proximate the corner interface  14  ( FIG. 6 ) prior to depositing a second coating layer  32 . The second coating layer  32  is then deposited toward and through the second mesh  26  ( FIG. 7 ). Subsequently, the second mesh  26  is removed and the multi-layer coating  16  remains within the corner interface  14  ( FIG. 8 ). 
         [0026]    The mesh assembly  18  may alternatively or conjunctively comprise one or more consumable meshes. By consumable, it should be appreciated that one or more meshes are positioned and attached proximate the corner interface  14  prior to depositing of the coating  16 , however, in contrast to the removable mesh, the consumable mesh is integrated with the coating  16  upon deposition of the coating onto and through the mesh assembly  18 . The consumable mesh is consumed by, or integrated with, the coating  16  in a variety of ways. First, this may be accomplished by employing a mesh that is formed of a material that is of a compatible material makeup with the coating composition, such as a Silicon Carbide (SiC) mesh used in conjunction with a ceramic coating. Alternatively, a process such as fusion of the mesh due to heat of a fusion active at the time of coating may be employed. Such an example is the use of a carbon or polymer mesh with a hot vapor deposition or plasma coating particles. These are merely exemplary methods in which the mesh assembly  18  may be consumed by, or integrated with, the coating  16 . It should also be understood that multiple coating layers may be formed by using one or more consumable meshes. 
         [0027]    Referring to  FIG. 9 , the corner interface  14  is shown as an outer corner  34  arrangement, where the first surface  10  and the second surface  12  define an angle therebetween. The angle between the first surface  10  and the second surface  12  is approximately 270 degrees, but it should be appreciated that numerous other angles are appropriate for use with the embodiments disclosed herein. This configuration is in contrast to the inner corner  22  arrangement described above and merely illustrates the applicability of the method with various interfaces of differing alignments. As is the case with the inner corner  22  arrangement, the outer corner  34  arrangement may be comprised of a continuous configuration ( FIG. 10 ) or a split configuration ( FIG. 11 ). 
         [0028]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.