Patent Publication Number: US-9850772-B2

Title: Seals with a thermal barrier for turbomachinery

Description:
BACKGROUND OF THE INVENTION 
     The present application relates generally to seals for reducing leakage, and more particularly to seals configured to operate within a seal slot to reduce leakage between adjacent stationary components of turbomachinery. 
     Leakage of hot combustion gases and/or cooling flows between turbomachinery components generally causes reduced power output and lower efficiency. For example, hot combustion gases may be contained within a turbine by providing pressurized compressor air around a hot gas path. Typically, leakage of high pressure cooling flows between adjacent turbine components (such as stator shrouds, nozzles, and diaphragms, inner shell casing components, and rotor components) into the hot gas path leads to reduced efficiency and requires an increase in burn temperature, and a decrease in engine gas turbine efficiency to maintain a desired power level as compared to an environment void of such leakage. Turbine efficiency thus can be improved by reducing or eliminating leakage between turbine components. 
     Traditionally, leakage between turbine component junctions is treated with metallic seals positioned in the seal slots formed between the turbine components, such as stator components. Seal slots typically extend across the junctions between components such that metallic seals positioned therein block or otherwise inhibit leakage through the junctions. However, preventing leakage between turbine component junctions with metallic slot seals positioned in seal slots in the turbine components is complicated by the relatively high temperatures produced in modern turbomachinery. Due to the introduction of new materials, such as ceramic-matrix composite (CMC) turbine components, that allow turbines to operate at higher temperatures (e.g., over 1,500 degrees Celsius) relative to traditional turbines, conventional metallic turbine slot seals for use in seal slots may not be adequate. 
     Preventing leakage between turbine component junctions with metallic seals is further complicated by the fact that the seal slots of turbine components are formed by corresponding slot portions in adjacent components (a seal positioned therein thereby extending across a junction between components). Misalignment between these adjacent components, such as resulting from thermal expansion, manufacturing, assembly and/or installation limitations, etc., produces an irregular seal slot contact surface that may vary in configuration, shape and/or magnitude over time. Such irregularities in the seal slot contact surface allow for leakage across a slot seal positioned within the seal slot if the seal does not flex, deform or otherwise account for such irregularities. Unfortunately, many conventional metallic shims that account for such irregular seal slot contact surfaces due to misalignment of adjacent turbine components may not adequately withstand increases in operating temperatures of turbines. 
     Accordingly, composite turbomachinery component junction seals configured for use in typical turbine seal slots that withstand the increasingly higher operating temperatures of turbines and conform to irregularities in the seal slot contact surface would be desirable. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present disclosure provides a seal assembly for positioning within a seal slot formed at least partially by adjacent turbomachinery components to seal a gap extending between the components. The seal assembly includes a pair of end blocks, ceramic fiber and a metallic shim. The pair of end blocks may be ceramic or glass end blocks each including a sealing surface and a support surface. The ceramic fiber may overly at least a portion of the support surfaces of the end blocks. The metallic shim may overly at least a portion of the ceramic fiber and include a plurality of tabs. The plurality of tabs of the metallic shim may engage the end blocks to couple the end blocks, ceramic fiber and metallic shim. 
     In some embodiments, the pair of end blocks may abut along engagement surfaces thereof to form a joint, and the metallic shim may include at least one tab positioned on a first side of the joint and at least a second tap positioned on a second side of the joint that substantially opposes the first side of the joint. In some such embodiments, the joint between the end blocks may extend along the gap between the turbomachinery components when the seal assembly is positioned within the seal slot. 
     In some embodiments, the pair of end blocks may abut at engagement surfaces of the end blocks that extend along a length direction of the end blocks and a thickness direction extending between the sealing surfaces and the support surfaces of the end blocks, and the engagement surfaces may be configured to allow movement of the end blocks with respect to each other at least along the thickness direction. In some such embodiments, the metallic shim and the ceramic fiber may be deformable to allow the movement of the end blocks with respect to each other at least along the thickness direction. In some other such embodiments, the engagement surface of each of the end blocks may include at least a portion that extends along a width direction of the end blocks as it extends in the thickness direction. In some such embodiments, the engagement surface of each of the end blocks may include a planar surface extending between the sealing surface and the support surface of the respective end block. In some other such embodiments, the engagement surface of one of the end blocks may define a concave shape extending along the width direction, and the other of the end blocks may define a convex shape extending along the width direction. 
     In some embodiments, the end blocks may each include a least one channel configured to accept at least a portion of the metallic shim therein. In some such embodiments, each of the end blocks may include a channel positioned on substantially opposing sides of the end blocks along a length direction of the end blocks, and the plurality of tabs of the metallic shim may be positioned on substantially opposing sides of a construct formed by the end blocks along a width direction of the end blocks. In some such embodiments, the channels of each of the end blocks may be formed on the sealing surface of the end blocks, and the plurality of tabs of the metallic shim may extend along a thickness direction extending between the support surface and the sealing surface of the end blocks. In some other embodiments, end blocks may include channels positioned on substantially opposing sides of a construct formed by the end blocks along a width direction of the end blocks, and recesses positioned on substantially opposing sides of the end blocks along a length direction of the end blocks, and the channels and recesses may be positioned between the support surface and the sealing surface of the end blocks. In some such embodiments, the plurality of tabs of the metallic shim may extend along a thickness direction extending between the support surface and the sealing surface of the end blocks may be configured such that at least one tab is positioned at least partially within each of the channels and the recesses. 
     In some embodiments, the plurality of tabs may exert a pre-loaded force against the end blocks at least when the seal assembly is at ambient temperature. In some embodiments, the seal assembly may be installed in the seal slot, and the ceramic fiber may thermally insulate the metallic shim from the seal slot. In some embodiments, the ceramic fiber may include woven metal oxide fibers. In some such embodiments, the metal oxide fibers may be Al2O3 or Al2O3 and SiO2 fiber. 
     In another aspect, the present disclosure provides a turbomachine including a first turbine component, a second turbine component adjacent the first turbine component, and a seal. The first and second turbine components may form at least a portion of a seal slot extending across a gap between the turbine components. The seal may be positioned within the seal slot of the first and second turbine components and extend across the gap therebetween. The seal may include a pair of end blocks, ceramic fiber, and a metallic shim. The pair of end blocks may be a pair of ceramic or glass end blocks each including a sealing surface and a support surface. The ceramic fiber may overly at least a portion of the support surfaces of the end blocks. The metallic shim may overly at least a portion of the ceramic fiber and include a plurality of tabs. The plurality of tabs of the metallic shim may engage the end blocks to couple the end blocks, ceramic fiber and metallic shim. 
     In some embodiments, the pair of end blocks may abut along engagement surfaces thereof that extend along a length direction of the end blocks and a thickness direction extending between sealing surface and a support surface of the end blocks, and the engagement surfaces may be configured to allow the movement of the end blocks with respect to each other at least along the thickness direction. In some embodiments, the pair of end blocks may each include a least one channel configured to accept at least a portion of the metallic shim therein. 
     These and other objects, features and advantages of this disclosure will become apparent from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary seal assembly for use in a seal slot of a turbine according to the present disclosure; 
         FIG. 2A  is a perspective view of a first end block of the seal assembly of  FIG. 1 ; 
         FIG. 2B  is a front view of the first end block of the seal assembly of  FIG. 1 ; 
         FIG. 2C  is a side view of the first end block of the seal assembly of  FIG. 1 ; 
         FIG. 2D  is an enlarged side view of an end portion of the first end block of the seal assembly of  FIG. 1 ; 
         FIG. 3A  is a perspective view of a second end block of the seal assembly of  FIG. 1 ; 
         FIG. 3B  is a front view of the second end block of the seal assembly of  FIG. 1 ; 
         FIG. 3C  is a side view of the second end block of the seal assembly of  FIG. 1 ; 
         FIG. 4  is a perspective view of a sub-assembly of the first and second end blocks of the seal assembly of  FIG. 1 ; 
         FIG. 5  is a perspective view of a sub-assembly of the first and second end blocks and ceramic fabric of the seal assembly of  FIG. 1 ; 
         FIG. 6  is a side cross-sectional view of the seal assembly of  FIG. 1  positioned within a seal slot to seal an exemplary junction between turbine components; 
         FIG. 7  is a perspective view of another exemplary seal assembly for use in a seal slot of a turbine according to the present disclosure; 
         FIG. 8  is a perspective view of a sub-assembly of first and second end blocks of the seal assembly of  FIG. 7 ; 
         FIG. 9  is an enlarged perspective view of a portion of the first end block of the seal assembly of  FIG. 7 ; 
         FIG. 10  is an enlarged perspective view of a portion of the second end block of the seal assembly of  FIG. 7 ; 
         FIG. 11  is a cross-sectional view of the first end block of the seal assembly of  FIG. 7 ; 
         FIG. 12A  is another cross-sectional view of the first end block of the seal assembly of  FIG. 7 ; 
         FIG. 12B  is a cross-sectional view of the second end block of the seal assembly of  FIG. 7 ; and 
         FIG. 13  is a perspective view of a sub-assembly of the first and second end blocks and ceramic fabric of the seal assembly of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters are not exclusive of other parameters of the disclosed embodiments. Components, aspects, features, configurations, arrangements, uses and the like described, illustrated or otherwise disclosed herein with respect to any particular seal embodiment may similarly be applied to any other seal embodiment disclosed herein. 
     Composite turbomachinery component junction seals configured for use in turbine seal slots (e.g., composite turbine slot seals), and methods of manufacturing and using same, according to the present disclosure are configured to withstand the relatively high operating temperatures of turbines including CMC components and/or conform to irregularities in the seal slot contact surface. In particular, the composite slot seals are configured to substantially prevent chemical interaction and substantially limit thermal interaction of metallic components of the composite slot seals with the hot gas flow/leakage and/or the seal slot itself. In this way, the composite slot seals provided herein allow for use in high temperature turbine applications. In addition to high temperature operation, the composite slot seals of the present disclosure are configured to conform to irregularities on the seal slot contact surface to decrease leakage due to seal slot surface misalignment and/or roughness. 
     As shown in  FIGS. 1-6 , the exemplary seal  10  may be a seal assembly including at least one pair of non-metallic end blocks  12 A,  12 B, at least one metallic shim  16 , and ceramic fiber  14  between the end blocks  12 A,  12 B and the at least one metallic shim  16  in the thickness T direction of the shim  10 . When utilized in a seal slot of a turbine engine, the seal  10  may substantially block off or seal at least one junction or gap between turbine components and the ceramic fiber  14  (and, potentially, the end blocks  12 A,  12 B) may prevent at least the metallic shim  16  from reaching potentially harmful high temperatures (e.g., temperatures that result in silicide formation, thermal creep and/or increased wear of at least the metallic shim  16 ). Stated differently, the ceramic fiber  14  (and, potentially, the end blocks  12 A,  12 B) allows for the seal  10  to include the metallic shim  12  and yet be utilized in high temperature gas turbine applications without degradation of the metallic shim  12 . 
     The at least one pair of end blocks  12 A,  12 B may be configured to engage sealing surfaces of a seal slot formed by at least two turbine components to seal a junction, joint or gap extending between the components, as shown in  FIG. 6  and described further below. As such, the end blocks  12 A,  12 B may be made from a material that can withstand the high temperatures experienced in a seal slot of a turbine engine, such as a modern high temperature turbine including CMC components, and potentially may be machinable. For example, the end blocks  12 A,  12 B may be made from, or include, a ceramic or a glass material. In some embodiments, the end blocks  12 A,  12 B may be ceramic matrix composite (CMC) end blocks  12 A,  12 B including fibers and/or a matrix stable at temperatures above at least 1,800° C., such as fibers and/or a matrix of or including alumina, zirconia, silicon carbide (SiC), or carbon. In some other embodiments, the end blocks  12 A,  12 B may be glass end blocks  12 A,  12 B. In some embodiments, the end blocks  12 A,  12 B may be formed of a crystalline, glassy or glass ceramic composite. For example, the end blocks  12 A,  12 B may include, silicon nitride, silicon carbide, intermetallic compounds such as MAX phase materials (Ti2AlC) and combinations thereof. In some embodiments, the end blocks  12 A,  12 B may be formed of a machinable glass ceramic material. In some such embodiments, the end blocks  12 A,  12 B may be formed of a borosilicate glass material. For example, in some such embodiments the end blocks  12 A,  12 B may be formed of a machinable glass-ceramic sold under the trademark Macor® by Corning Inc. of Corning, N.Y. The end blocks  12 A,  12 B may each also be substantially effective in substantially preventing the passage of substances therethrough. For example, the end blocks  12 A,  12 B may be substantially solid or otherwise substantially impervious to at least one of gases, liquids and solids at pressures and temperatures produced in turbomachinery. 
     As shown in  FIGS. 2A-3 , each end block  12 A,  12 B may include or define a base portion  20 , substantially opposing side wall portions  30  extending from the base portion  20  in the thickness direction T of the seal  10 , and a distal portion  34  extending from each of the side walls  30 . The base portion  20  of each end block  12 A,  12 B may include or define an exterior sealing surface or side  22 . In some embodiments, the exterior sealing surface  22  of each end block  12 A,  12 B may be substantially planar (in a neutral state of the end blocks  12 A,  12 B). As explained further below, the exterior sealing surface  22  of each end block  12 A,  12 B may be configured to sealingly engage at least the sealing surfaces of a seal slot formed by first and second turbine components to substantially prevent gases, liquids and/or solids from migrating through a gap or joint between the first and second components. As such, the sealing surface  22  of each end block  12 A,  12 B may be shaped, sized and/or otherwise configured such that when the seal  10  is utilized in a seal slot of a turbine, the sealing surfaces  22  sealingly engage at least the corresponding sealing surfaces of the seal slot of the first and second turbine components. 
     As also shown in  2 A- 3 , the base portion  20  of each end block  12 A,  12 B may include or define a support surface or side  24 . The support surface  24  of each end block  12 A,  12 B may substantially oppose the sealing surface  22  thereof. In some embodiments, the support surface  24  of each end block  12 A,  12 B may be substantially planar (in a neutral state of the end blocks  12 A,  12 B). As explained further below, the support surfaces  24  of the end blocks  12 A,  12 B may act in concert with each other to provide support for ceramic fiber  14  positioned thereon or thereover. As such, the support surface  24  of each end block  12 A,  12 B may be shaped, sized and/or otherwise configured to provide support for ceramic fiber  14  thereon or thereover. 
     The end blocks  12 A,  12 B may further include substantially opposing side walls  30  extending from the base portion  20  along the thickness T of the seal  10  in a direction extending at least generally from the sealing surface  22  to the support surface  24 . In this way, the side walls  30  of the end blocks  12 A,  12 B may define or include exterior or outer surfaces  32  that define the length L of the seal  10  (i.e., define the limit of the seal  10  in the length L direction), as shown in  FIGS. 1 and 6 . Stated differently, the side walls  30  of the end blocks  12 A,  12 B may define or include exterior or outer surfaces  32  that define the ends or outer edges of the seal  10  in the length direction L, as shown in  FIGS. 1 and 6 . In some embodiments, the side walls  30  may be substantially planar and extend substantially perpendicular to the base portion  20 . For example, the exterior or outer surfaces  32  of the side walls  30  may be oriented substantially perpendicular to the sealing surface  22  and/or the support surface  24  of the base portion  20 . However, in other embodiments the exterior or outer surfaces  32  of the side walls  30  may not be planar and/or oriented substantially perpendicular the sealing surface  22  and/or the support surface  24  of the base portion  20 . Further, the side walls  30  may not be positioned on substantially opposing sides of the base portion  20  and/or define the length L of the seal  10 . For example, the side walls  30  may define the width W of the seal  10 . 
     The end blocks  12 A,  12 B may each further include distal portions  34  extending from the side walls  30  that are spaced from the base portion  20  along the thickness direction T of the seal, as shown in  FIGS. 1-6 . The distal portions  34  may extend substantially away from the exterior sides  32  of the side walls  30  along the length L of the seal  10  (e.g., towards the inner portion of the seal  10 ). Stated differently, the distal portions  34  of the end blocks  12 A,  12 B may extend from the side walls  30  and toward the interior or central portion of the seal  10 , such as along the length L of the seal  10 . In some embodiments, the distal portions  34  may be substantially planar and extend substantially parallel to the base portion  20 . For example, the distal portions  34  may each include or define an exterior or outer upper surface  36  that is distal to the base portion  20  and an inner or lower surface that is proximate to the support surface  24  of the base portion  12  of the respective end block  12 A,  12 B, and such surfaces may be planar and oriented substantially parallel to the sealing surface  22  and/or the support surface  24  of the base portion  20  (and/or substantially perpendicular to the side walls  20 ). However, in other embodiments the upper surfaces  36  and/or lower surfaces of the distal portions  34  may not be planar and/or oriented substantially parallel to the sealing surface  22  and/or the support surface  24  of the base portion  20  (and/or substantially perpendicular to the side walls  20 ). The exterior or outer upper surfaces  36  of the distal portions  34  of the end blocks  12 A,  12 B may define the top or upper end of the seal  10  in the thickness T direction, as shown in  FIGS. 1 and 6 . As such, the distance between the exterior or outer upper surfaces  36  and the sealing surfaces  22  of the end blocks  12 A,  12 B may define or determine the thickness T of the seal  10 , as shown in  FIGS. 1 and 6 . 
     As shown in  FIGS. 1-6 , the distal portions  34  may extend from the side walls  30  and toward the interior or central portion of the seal  10  substantially along the base portion  20 . In this way, the base portion  20 , side wall positions  30 , and distal portions  34  may from a “C” shape as shown in  FIGS. 2C, 2D and 3C  (e.g., when viewed along the width W direction). The distal portions  34  may terminate before connecting or reaching each other, as shown in  FIGS. 1-6 . As such, at least an interior or central portion of the base portion  20  of each end block  12 A,  12 B may not be covered by or include the distal portions  34 . At least an interior or central portion of the support surface  24  (e.g., along the length L) of each end block  12 A,  12 B may thereby be exposed or “open” in the thickness T direction of the seal  10 . 
     The inwardly-facing C-shape formed by the inner or interior surfaces of the side wall positions  30  and the distal portions  34 , and the support surface  24  of the base portion  20 , of each end block  12 A,  12 B may form a channel, slot, groove or the like  40  that is accessible from an interior (e.g., of the length L) of the seal  10 , as shown in  FIGS. 1-6 . The end blocks  12 A,  12 B may be configured such that the channels  40  extend along the entirely of the width W of the end blocks  12 A,  12 B. In some embodiments, the channels  40  may be positioned or arranged on substantially opposing sides of the end blocks  12 A,  12 B, such as opposing ends of the end blocks  12 A,  12 B along the length L direction. 
     The end blocks  12 A,  12 B may be configured such that they mate in an abutting relationship to form a construct that supports the ceramic fiber  14  and metallic shim  16  to form the seal assembly  10 , as shown in  FIGS. 1 and 4-6 . As shown in  FIG. 4 , the end blocks  12 A,  12 B may be configured or arranged such that they are adjacent to and abut each other along the width W direction, and are substantially aligned along the length L and thickness T directions (in a neutral state of the seal  10 ). In some embodiments, the support surfaces  24  of the end blocks  12 A,  12 B may be planar, and when the end blocks  12 A,  12 B are coupled, engaged or in abutment (and in a neutral state) the support surfaces  24  may be coplanar to form a two-piece planar surface to support the ceramic fiber  14  and metallic shim  16  thereon, as shown in  FIGS. 4 and 5 . Further, the end blocks  12 A,  12 B may be configured such that when they are coupled, engaged or in abutment (and in a neutral state) the channels  40  at respective ends or portions of the end blocks  12 A,  12 B mate and are substantially aligned or cooperate. When the end blocks  12 A,  12 B are coupled or in abutment, outer lateral sides or surfaces  38  of the end blocks  12 A,  12 B along the width W direction may form or define the outer lateral sides or surfaces of the construct formed by the end blocks  12 A,  12 B. As explained further below, the shim  16  may engage and/or couple to the outer lateral sides of the end blocks  12 A,  12 B to, at least in part, couple or secure the end blocks  12 A,  12 B to each other. The outer lateral sides or surfaces  38  of the end blocks  12 A,  12 B may be formed or defined by the base portion  20 , side wall portions  30  and distal portions  34 , as shown in  FIGS. 2C and 3C . 
     As shown in  FIGS. 1-5 , the end blocks  12 A,  12 B may include or define inner engagement surfaces  26  that engage or abut with each other and form a joint or seam  18  therebetween when the end blocks  12 A,  12 B are coupled or in abutment (and in a neutral state) and form the seal  10 . In some embodiments, the engagement surfaces  26  may extend through the thickness T of the end blocks  12 A,  12 B such that engagement surfaces  26  are formed or defined by the base portion  20 , the side wall portions  30 , and the distal portions  34 , as shown in  FIGS. 2C and 3C . The engagement surfaces  26  may be configured to allow the end blocks  12 A,  12 B to move with respect to each other, while maintaining contact or engagement therebetween, to allow the seal  10  to accommodate or adapt to seal slot misalignment or other situations involving non-aligned seal slot surfaces (e.g., misalignment along the thickness T and/or width W directions) while preventing an increase in leakage across the seal  10 . In some embodiments, the engagement surfaces  26  of the end blocks  12 A,  12 B may be configured such that the joint or seam  18  therebetween substantially corresponds to (e.g., aligns with) a gap or junction between turbine components forming a seal slot for the seal  10  to allow or accommodate movement of the components, such as movement in the thickness T direction. Further, to provide contact or engagement of the end blocks  12 A,  12 B along the length L of the end blocks  12 A,  12 B, the shape, size, orientation or the like of the engagement surfaces  26  may substantially correspond or mimic each other (e.g., a mirror image). 
     In some embodiments, the engagement surfaces  26  of the end blocks  12 A,  12 B may be planar and angled as they extend along the thickness direction T. For example, as shown in  FIGS. 2B and 3B , the engagement surfaces  26  of the end blocks  12 A,  12 B may be planar and angled along the width W direction as they extend along the thickness direction T. In such an embodiment, to provide for movement between the end blocks  12 A,  12 B while maintaining contact, abutment or engagement of the engagement surfaces  26 , the engagement surface  26  of a first end block  12 A may be angled toward the second end block  12 B as it extends in the thickness direction T from the engagement surface or side  22  to the upper surface or side  36 , while the second end block  12 B may conversely be angled away the first end block  12 A as it extends in the thickness direction T from the sealing surface or side  22  to the upper surface or side  36 . In this way, the engagement surfaces  26  of the end blocks  12 A,  12 B may allow for motion or translation (e.g., sliding motion) between the end blocks  12 A,  12 B in the width W direction that results or provides relative translation of the end blocks  12 A,  12 B in the thickness T direction (and also allows for relative translation along the length direction L) while maintaining abutment or engagement thereof. As explained further below, other geometries or configuration of the engagement surfaces  26  of the end blocks  12 A,  12 B may allow for movement between end blocks  12 A,  12 B (e.g., along the thickness T, width W and/or length L directions), potentially while maintaining abutment or engagement thereof. 
     With the end blocks  12 A,  12 B in engagement or abutment as shown in  FIG. 4 , the ceramic fiber  14  may be positioned on or over the supporting surfaces  24  as shown in  FIG. 5 . As noted above, when the end blocks  12 A,  12 B are adjacent or in engagement or abutment, the supporting surfaces  24  may cooperate to form a platform, surface(s) or support mechanism for placement of the ceramic fiber  14  thereon or thereover. In some embodiments, the ceramic fiber  14  may include at least one layer of ceramic fiber or cloth that substantially covers or overlies the supporting surfaces  24  of the end blocks  12 A,  12 B. For example, the at least one layer of ceramic fiber  14  may be positioned on or over (e.g., abut) the supporting surfaces  24  and extend into the channels  40  of the blocks  12 A,  12 B, as shown in  FIG. 5 . In such embodiments, the end blocks  12 A,  12 B and/or ceramic fiber  14  may be configured such that the ceramic fiber  14  fills or occupies only a portion of channels  40  in the thickness T direction. In alternative embodiments (not shown), the ceramic fiber  14  may not substantially cover or overlie supporting surfaces  24  and/or be positioned within at least one channel  40 . The ceramic fiber  14  may be relatively flexible or deformable such that the ceramic fiber  14  does not prevent relative movement of the end blocks  12 A,  12 B. Stated differently, the ceramic fiber  14  may be configured to allow the end blocks  12 A,  12 B to move with respect to each other, such as in the thickness T direction, in response to misaligned or a “rough” surface profile of a seal slot in which the seal  10  is utilized. 
     The ceramic fiber  14  may preferably act as a thermal barrier to the metallic shim  16  positioned on or over the ceramic fiber  14 . Stated differently, the ceramic fiber  14  is preferably configured to decrease the conductance of heat from the seal slot holding the seal  10  to the metallic shim  16  (such as from the turbine components forming the seal slot and/or a hot flow passing through the gap or junction between the components and acting on the seal  10 ). As explained further below, the seal  10  may be utilized in a seal slot and oriented such that the sealing surface  22  of the end blocks  12 A,  12 B is positioned adjacent to, or interacts with, a flow or material (e.g., a combustion airflow) that is hotter than a flow or material (e.g., a cooling airflow) that is positioned adjacent to, or interacts with, the exterior surface  48  of the metallic shim  16 . As such, the ceramic fiber  14  (potentially in concert the end blocks  12 A,  12 B) may be effective in preventing (or at least reducing the likelihood of) the metallic shim  16  from reaching potentially harmful high temperatures during use of the seal  10  in turbomachinery (e.g., temperatures that result in silicide formation, thermal creep and/or increased wear of the at least the metallic shim  16 ). Stated differently, the ceramic fiber  14  (and, potentially, the end blocks  12 A,  12 B) is preferably configured to allow the seal  10  to include the metallic shim  12  and be utilized in modern high temperature gas turbine applications, such as turbines including CMC components, without degradation of the metallic shim  18 . 
     As such, the ceramic fiber  14  may be any ceramic fiber material that thermally insulates or otherwise acts as a thermal barrier to the metallic shim  16 . In some embodiments, the ceramic fiber  14  (or the ceramic fiber  14  and the end blocks  12 A,  12 B) is configured to prevent the metallic shim  16  from reaching about 1800 degrees Fahrenheit when the seal  10  is used in a turbine engine, such as a turbine including CMC components. In some embodiments, the ceramic fiber  14  (or the ceramic fiber  14  and the end blocks  12 A,  12 B) is configured to prevent (or at least reducing the likelihood of) the metallic shim  16  from reaching about 1,500 degrees Fahrenheit when the seal  10  is used in a turbine engine, such as a turbine including CMC components. 
     The ceramic fiber  14  may be made of metal oxide fibers that have been woven or otherwise manufactured into a ceramic textile product, such as a fabric, cloth, tape, or sleeve. In some embodiments, the ceramic fiber  14  may be made of fibers of or including Al2O3 or Al2O3 and SiO2. For example, the ceramic fibers may be at least about 99 weight % Al2O3, or about 85 weight % Al2O3 and about 15 weight % SiO2. In some embodiments, the ceramic fiber  14  may be made of fibers including a crystalline or crystal structures based on alpha-Al2O3 or alpha-Al2O3 and mullite. In some embodiments, the ceramic fiber  14  may be at least one layer of woven ceramic fibers, such as Nextel™ ceramic textiles, fabrics or fibers sold by 3M™. In some such embodiments, the ceramic fiber  14  may be 3M™ Nextel™ 610 Ceramic Fiber or 3M™ Nextel™ 720 Ceramic Fiber. 
     As discussed above, to provide further thermal insulation or shielding to the metallic shim  16  of the seal  10  above the protection afforded by the ceramic fiber  14 , the seal  10  may include glass end blocks  12 A,  12 B. Such glass end blocks  12 A,  12 B may lower the conductance of heat from the seal slot holding the seal  10  to the metallic shim  16  from that provided by the ceramic fiber  14  alone. For example, the glass end blocks  12 A,  12 B may include a relatively low thermal conductivity (e.g., as compared to ceramic (e.g., CMC) end blocks  12 A,  12 B) that acts in concert with the ceramic fiber  14  to decrease the conductance of heat to the metallic seal  16  to prevent (or at least reduce the likelihood of) the metallic shim  16  from reaching potentially harmful high temperatures during use of the seal  10  in turbomachinery. Glass end blocks  12 A,  12 B may also become relatively soft, deformable or pliable at temperatures found in seal slots of turbomachinery. In some such embodiments, the glass end blocks  12 A,  12 B may be configured to deform and conform (e.g., due to the temperature and pressure produced/experienced in seal slots of turbomachinery) to any misalignment or roughness profile within a seal slot to prevent an increase in leakage across the seal  10 . 
     The seal assembly  10  may include at least one shim  16  that substantially covers or overlies the ceramic fiber  14  and/or the supporting surfaces  24  of the end blocks  12 A,  12 B. For example, the at least one shim  16  may be positioned on or over (e.g., abut) the ceramic fiber  14  (and over the supporting surfaces  24 ) and extend into the channels  40  of the blocks  12 A,  12 B, as shown in  FIG. 1 . In such embodiments, the end blocks  12 A,  12 B and/or ceramic fiber  14  may be configured such that the shim  16  and the ceramic fiber  14  substantially fills or occupies the channels  40  in the thickness T direction. In some embodiments, the channels  40  may exert a compressive force to the portion of the shim  16  (and, potentially, the ceramic fiber  14 ) positioned therein in the thickness T direction at least in a neutral state of the seal  10  (e.g., when the seal  10  is at ambient temperature). As the shim  10  may be positioned within the channels  40  of both of the end blocks  12 A,  12 B and the channels  40  may be positioned on substantially opposing sides or portions of the end blocks  12 A,  12 B (e.g., along sides or portions that define the length L of the end blocks  12 ,  12 B), the shim  16  and the channels  40  may effectively couple or fix the end blocks  12 A,  12 B with respect to each other along at least one direction (e.g., along the length L direction). 
     The at least one metallic shim  16  may be effective in substantially preventing the passage of substances therethrough. For example, the metallic shim  16  may be substantially solid or otherwise substantially impervious to at least one of gases, liquids and solids at pressures and temperatures produced in turbomachinery. However, the metallic shim  16  may also provide flexibility at least in the thickness T direction at pressures and temperatures produced in turbomachinery to accommodate skews or offsets in the seal slot in which the seal  10  is utilized. For example, the metallic shim  16  may be relatively flexible or deformable such that the metallic shim  16  does not prevent relative movement (e.g., translation, twisting, bending, etc.) of the end blocks  12 A,  12 B. Stated differently, the metallic shim  16  may be configured to flex or deform to allow the end blocks  12 A,  12 B to move with respect to each other, at least in the thickness T direction, in response to misaligned or a “rough” surface profile of the seal slot in which the seal  10  is utilized. 
     In one embodiment, at least the portion of the shim  16  that overlies the ceramic fiber  14  and/or the support surfaces  24  of the end blocks  12 A,  12 B is a substantially solid metallic member or portion. The metallic shim  16  may be a high temperature metallic alloy or super alloy. For example, in some embodiments the shim  16  may be made from stainless steel or a nickel based alloy (at least in part), such as nickel molybdenum chromium alloy, Haynes 214, or Haynes 214 with an aluminum oxide coating. In some embodiments, the shim  16  may be made of a metal with a melting temperature of at least 1,500 degrees Fahrenheit, and more preferably at least 1800 degrees Fahrenheit. In some embodiments, the shim  16  may be made of a metal with a melting temperature of at least 2,200 degrees Fahrenheit. 
     As shown in  FIG. 1 , the metallic shim  16  may include a sealing portion  46  that substantially covers or overlies the ceramic fiber  14  and/or the support surfaces  24  of the end blocks  12 A,  12 B. In some embodiments, the ceramic fiber  14  may be adjacent, abut or underneath the entirety of the sealing portion  46  of the metallic shim  16 . In this way, the ceramic fiber  16  may insulate at least the entirety of the sealing portion  46  of the metallic shim  16 . In other embodiments, at least one portion of the sealing portion  46  of the metallic shim  16  may be void of the ceramic fiber  14 . The shape or configuration of the sealing portion  46  of the metallic shim  16  may substantially correspond to that of the support surfaces  24  of the end blocks  12 A,  12 B. For example, the inner side, surface or portion of the sealing portion  46  may engage the ceramic fiber  14  and be positioned proximate to the support surfaces  24  of the end blocks  12 A,  12 B. As such, the inner side of the sealing portion  46  may be substantially planar (in a neutral state of the seal  10 ) and includes the substantially same width W and length L as that of the ceramic fiber  14  and/or support surfaces  24 . 
     As also shown in  FIG. 1 , a portion of an outer side or surface  48  of the sealing portion  46  of the metallic shim  16  may be exposed. For example, the outer side or surface  48  of the sealing portion  46  that is not positioned in the channels  40  may be exposed. The exposed outer side or surface  48  of the sealing portion  46  of the metallic shim  16  may be configured to engage or interact with a cooling high pressure air flow flowing through at least one gap or joint between at least first and second components forming a seal slot (at least in part) holding the seal  10 . The cooling high pressure air flow acting at least on the exposed outer side or surface  48  of the metallic shim  16  may force or press the seal (e.g., the sealing sides or surfaces  22  of the end blocks  12 A,  12 B) against or in contact with the sealing surfaces of the seal slot to substantially prevent gases, liquids and/or solids from migrating through the gap or joint. As such, the sealing portion  46  of the metallic shim  16  may be substantially impervious to liquids, gases and/or solids at pressures experienced in turbomachinery such that the seal  10  provides at least a low leakage rate past the seal slot. However, as described above, the sealing portion  46  of the metallic shim  16  may be flexible to allow relative movement between the end blocks  12 A,  12 B to account for skews, offsets or other non-aligned configurations of the sealing surfaces of the turbine components forming a seal slot that holds or retains the seal  10 . 
     The metallic shim  16  may also include a plurality of tabs or projections  50  that extend from the sealing portion  46  on at least one side, edge or portion thereof that is not positioned within a channel  40 , as shown in  FIG. 1 . The tabs  50  may be provided on substantially opposing sides of the shim  16 . In the exemplary embodiment shown in  FIG. 1 , the sides of the sealing portion  46  defining the length L of the shim  16  are positioned within the channels  40 , and the tabs  50  extend from the sides of the sealing portion  46  that extend between the channels  40  and define the width W of the shim  16 . A plurality of tabs  50  may be provided on each side or portion of the sealing portion  46  that includes a tab  50 . 
     The tabs  50  of the metallic shim  16  may be configured to hold together, couple, affix, abut or engage the end blocks  12 A,  12 B in at least one direction, such as along the width W direction. Further, the tabs  50  may couple or affix the shim  16  and the ceramic fiber  14  to the end blocks. For example, the tabs  50  may be angled or offset from the sealing portion  46  in the T thickness direction such that they extend over or past the outer edges or sides of the ceramic fiber  14  and the end blocks  12 A,  12 B. As shown in  FIG. 1 , the tabs  50  may extend away from the outer side or surface  48  of the sealing portion  46  and toward the sealing side or surface  22  of the end blocks  12 A,  12 B such that the tabs  50  extend past or over the outer lateral sides or surfaces of the ceramic fiber  14  and the outer lateral sides or surfaces  38  of the end blocks  12 A,  12 B (e.g., along the length L of the seal  10 ). The tabs  50  of the metallic shim  16  and the channels  40  of the end blocks  12 A,  12 B may cooperate to mechanically hold together, couple, affix or engage the end blocks  12 A,  12 B, ceramic fiber  14  and metallic shim  16  along each of the length L, width W, and thickness T directions. However, as noted above the metallic shim  16  is relatively flexible and the joint  18  extending between the end blocks  12 A,  12 B is configured to provide or allow movement of the end blocks  12 A,  12 B in at least the thickness T direction so that the seal  10  can maintain sealing engagement with a seal slot of a turbomachine that is (or becomes) offset or includes a “rough” profile. 
     The metallic shim  16  and the ceramic or glass end blocks  12 A,  12 B may include different coefficients of thermal expansion (hereinafter CTE). As a result, even though the metallic shim  16  may be cooler than the ceramic or glass end blocks  12 A,  12 B during use of the seal  10  in a seal slot of a turbomachine, the metallic shim  16  may expand or enlarge more than the ceramic or glass end blocks  12 A,  12 B. To account for the potential expansion of the metallic shim  16  with respect to the ceramic or glass end blocks  12 A,  12 B, the tabs  50  may be positioned against, adjacent or along the sides or surfaces of the end blocks  12 A,  12 B (e.g., deformed such that they are offset or angled with respect to the sealing portion  46  and against or adjacent the outer lateral sides or surfaces  38  of the end blocks  12 A,  12 B) with at least the metallic shim  16  heated, such as heated to at least about an operating temperature of a turbomachine. For example, the seal  10  may be heated to at least 1500 degrees Fahrenheit, or at least 1800 degrees Fahrenheit, and the tabs  50  may be deformed or positioned against or adjacent the sides or surfaces of the end blocks  12 A,  12 B. As the tabs  50  may be deformed or positioned in a heated state of the metallic shim  16  and the tabs  50  may be positioned on substantially opposing sides of the seal  10 , the tabs  50  may be pre-stressed or pre-loaded at ambient temperature such that they exert a compressive force to the end blocks  12 A,  12 B. In some embodiments, the tabs  50  may be pre-loaded such that they are configured to exert a load or force, such as a compressive force, to the end blocks  12 A,  12 B at ambient temperature and at an operating temperature of the seal  10  (i.e., an operating temperature of a turbine). It is noted that that the load or force exerted by the tabs  50  against the end blocks  12 A,  12 B may be greater at ambient temperature that at an operating temperature. 
     The components of the seal  10  may include one or more protective coating (not shown) applied or positioned over or on surface thereof, or a portion thereof. For example, at least a portion of the metallic shim  16 , such as an outer or exposed surface thereof, may include at least one protective coating or layer. The protective coating(s) of the metallic shim  16  may be configured to substantially prevent or retard oxidation of the metallic shim  10 . In some embodiments, the protective coating(s) of the metallic shim  16  may include or substantially comprise an oxide, such as chromium oxide or alumina oxide. In some embodiments, the protective coating(s) of the metallic shim  16  may be configured to thermally insulate the metallic shim  10 . For example, the metallic shim  16  may include a thermal barrier coating (TBC) overlying the metallic shim  16  that is configured to further thermally insulate the metallic shim  16  (in addition to the thermal insulation provided by the ceramic fiber  14  and, potentially, the end blocks  12 A,  12 B). In some embodiments, the TBC on the metallic shim  16  may include multiple layers, such as at least one metallic bond coat formed on the metallic shim  16 , at least one thermally grown oxide (TGO) layer or region formed on or in the bond coat, and at least one ceramic topcoat formed or positioned on or over the TGO. In some embodiments, the ceramic topcoat may be composed of yttria-stabilized zirconia (YSZ) or a rare earth silicate or zirconate. The at least one ceramic topcoat may provide the largest thermal gradient of the TBC and function to the lower the temperature of any lower layers. 
     In some embodiments, the end blocks  12 A,  12 B may also include a protective coating. For example, at least a portion of the end blocks  12 A,  12 B, such the support surfaces  24  and/or the sealing surface  22 , may include at least one protective coating or layer. The protective coating(s) of the end blocks  12 A,  12 B may be configured to substantially prevent or retard recession due to volatilization of the end blocks  12 A,  12 B, and/or thermally insulate the end blocks  12 A,  12 B. As such, the end blocks  12 A,  12 B may include a TBC and/or an environmental barrier coating (EBC). For example, the end blocks  12 A,  12 B may include an EBC overlying at least a portion thereof that is configured to prevent recession of the end blocks  12 A,  12 B due to volatilization, and, potentially, further thermally insulate the metallic shim  16  (in addition to the thermal insulation provided by the ceramic fiber  14  and, potentially, the end blocks  12 A,  12 B). In some embodiments, the EBC on the end blocks  12 A,  12 B may include multiple layers, such as at least one bond coat formed on end blocks  12 A,  12 B and at least one topcoat formed or positioned on or over the at least one bond coat. It is noted that ceramic embodiments of the end blocks  12 A,  12 B, such as CMC end blocks  12 A,  12 B, may particularly benefit from an EBC protective coating to prevent recession due to volatilization when the seal  10  is used in high temperature and/or moist environments. 
       FIG. 6  illustrates a cross-sectional view along the width W of the exemplary slot seal assembly  10  positioned within an exemplary seal slot to seal an exemplary junction between turbine components. Specifically,  FIG. 6  shows a cross-section taken along the width W of a portion of an exemplary turbomachine including an exemplary first turbine component  142 , an adjacent exemplary second turbine component  144 , and the seal assembly  10  installed in the seal slot formed by the first and second components  142 ,  144 . The first and second turbine components  142 ,  144  may be first and second stator components, such as first and second nozzles of first and second stators, respectively. In other embodiments, the first and second components  142 ,  144  may be any other adjacent turbomachinery components, such as stationary or translating and/or rotating (i.e., moving) turbine components. Stated differently, the seals described herein, such as seal  10 , may be configured for, or used with, any number or type of turbomachinery components requiring a seal to reduce leakage between the components. 
     The cross-section of the exemplary components  142 ,  144  and the seal assembly  10  illustrated in  FIG. 6  is taken along a width W of the structures, thereby illustrating an exemplary width W and thickness/height T of the structures. It is noted that the relative width W, thickness T and cross-sectional shape of the structures illustrated in  FIG. 6  is exemplary, and the structures may include any other relative width, thickness and cross-sectional shape. Further, the length L of the structures (extending in-out of the page of  FIG. 6 ) may be any length, and the shape and configuration of the structures in the length L direction may be any shape or configuration. It is also noted that although only two exemplary turbine components  142 ,  144  forming one seal slot is shown, a plurality of components may form a plurality of seal slots that are in communication with one another. For example, a plurality of turbine components may be circumferentially arranged such that seal slots formed thereby are also circumferentially arranged and in communication with one another. In such embodiments, the seals according to the present disclosure, such as seal  10 , may be configured to span a plurality of seal slots to seal a plurality of gaps or junctions and thereby reduce leakage between a plurality of turbine components. 
     As shown in  FIG. 6 , the first and second adjacent turbine components  142 ,  144  may be spaced from one another such that a junction, gap or pathway  190  extends between the first and second adjacent components  142 ,  144 . Such a junction  190  may thereby allow flow, such as airflow, between the first and second turbine components  142 ,  144 . In some configurations, the first and second turbine components  142 ,  144  may be positioned between a first airflow  150 , such as a cooling airflow, and a second airflow  160 , such as hot combustion airflow. It is noted that the term “airflow” is used herein to describe the movement of any material or composition, or combination of materials or compositions, translating through the junction  190  between the first and second turbine components  142 ,  144 . 
     To accept a seal that spans across the junction  190 , and thereby block or otherwise cutoff the junction  190  and the first airflow  150  and the second airflow  160 , the first and second adjacent components  142 ,  144  may each include a seal slot, as shown in  FIG. 6 . In the exemplary illustrated embodiment, the first component  142  includes a first seal slot  170  and the second component includes a second seal slot  180 . The first and second seal slots  170 ,  180  may have any size, shape, or configuration capable of accepting a seal therein. For example, as shown in the illustrated exemplary embodiment in  FIG. 6 , the first and second seal slots  170 ,  180  may be substantially similar to one another and positioned in a mirrored relationship to define, in concert, a net slot or cavity that extends from within the first component  142 , across the junction  190 , and into the second component  144 . In this manner, the pair of first and second seal slots  170 ,  180  may jointly or cooperatively form a cavity or seal slot to support opposing portions of the seal assembly  10  such that the seal  10  passes through the junction  190  extending between the adjacent components  142 ,  144 . 
     In some arrangements with the first and second turbine components  142 ,  144  are adjacent, the first and second seal slots  170 ,  180  may be configured such that they are substantially aligned (e.g., in a mirrored or symmetric relationship). However, due to manufacturing and assembly limitations and/or variations, as well as thermal expansion, movement, or other factors, the first and second seal slots  170 ,  180  may be skewed, twisted, angled or otherwise misaligned. In other scenarios, the first and second seal slots  170 ,  180  may remain in a mirrored or symmetric relationship, but the relative positioning of the first and second seal slots  170 ,  180  may change (such as from use, wear or operating conditions). The term “misaligned” is used herein to encompass any scenario wherein seal slots have changed relative positions or orientations as compared to a nominal or initial position or configuration, such as a manufactured or assembled position or configuration. 
     With respect to the exemplary first and second seal slots  170 ,  180  of the exemplary first and second turbine components  142 ,  144  and the seal  10  of  FIG. 6 , in a misaligned configuration (not shown) the seal  10  is configured to account for the misalignment and maintain sealing contact of the end blocks  12 A,  12 B with the first and second seal slots  170 ,  180  to effectively cut off or eliminate the junction  190  extending between the first and second turbine components  142 ,  144  to thereby reduce or prevent the first and second airflows  150 ,  160  from interacting. More particularly, as shown in  FIG. 6  the first and second airflows  150 ,  160  may interact with the junction  190  such that the first airflow  150  is a “driving” airflow that acts against the outer side or surface  48  of the metallic shim  16  of the seal  10  to force the sealing side or surfaces  22  of the end blocks  12 A,  12 B against first side surfaces  135 ,  145  of the first and second seal slots  170 ,  180 , respectively. In such scenarios, the junction  18  formed by the engagement surfaces  26  of the end blocks  12 A,  12 B, and the flexible or deformable nature of the ceramic fiber  14  and the metallic shim  14 , may allow relative movement of the end blocks  12 A,  12 B (e.g., in the thickness T direction) as a result of the forces applied by the first airflow  150  (e.g., above that applied by the second airflow  160 ) to account for any misalignment between the first and second seal slots  170 ,  180 , but sufficiently stiff to resist being “folded” or otherwise “pushed” into the junction  190 . Stated differently, in such a scenario, the exemplary seal  10  may be preferably sufficiently flexible, but yet sufficiently stiff, to maintain sealing engagement of the sealing side or surfaces  22  of the end blocks  12 A,  12 B of the shim  16  with the first side surfaces  135 ,  145 , respectively, via the forces of the first airflow  150 . For example, the metallic shim  16 , the ceramic fiber  14 , and the end blocks  12 A,  12 B may be configured to allow the seal  10  to conform to irregularities on the seal slot contact surfaces  135 ,  145 . In addition to being sufficiently flexible to effectively seal the junction  190  in misalignment scenarios, as described above, the exemplary seal  10  may preferably be sufficiently stiff to satisfy assembly requirements. 
     The size of the seal  10  may be any size, but may be dependent upon, or at least related to, the components  142 ,  144  in which the seal  10  is installed. The thickness T of the exemplary seal  10  may be less than the thickness T 2  of the first and second seal slots  170 ,  180 , and thereby the thickness T 2  of the net slot created by the first and second seal slots  170 ,  180  when the first and second adjacent components  142 ,  144  are assembled. In some embodiments, the thickness T of the exemplary seal  10  may preferably be within the range of about 0.01 inches to about ¼ inches, and more preferably within the range of about 0.05 inches to about 0.1 inches. Similarly, the width W of the seal  10  may be less than the width W 2  of the net slot created by the first and second slots  170 ,  180  of the first and second components  142 ,  144 , respectively, and the gap  190  between the components  142 ,  144  when the components  142 ,  144  are installed adjacent to one another. In some embodiments, the width W of the exemplary seal  10  may preferably be within the range of about 0.125 inches to about 0.75 inches. 
     As shown in the illustrated embodiment in  FIG. 6 , for example, the seal  10  may be positioned and arranged within the seal slot (i.e., the first and second seal slots  170 ,  180 ) such that the first or cooling airflow  150  acts against the outer side or surface  48  of the sealing portion  46  of the metallic shim  16  (and the upper surfaces  36  of the distal portions  34 ) to force the exterior sealing surface  22  of each end block  12 A,  12 B against the first side surfaces  135 ,  145  of the first and second seal slots  170 ,  180 . Due to the impervious nature of the shim  16  and/or the end blocks  12 A,  12 B (and the end blocks  12 A,  12 B being in abutment), the seal  10  may thereby prevent the cooling airflow  150  from migrating through the gap  190  and into the second or hot combustion airflow  160 . Further, the ceramic fiber  14  (and, potentially, the end blocks  12 A,  12 B) protects the metallic shim  16  from the high temperatures of the combustion airflow  160 . 
     In this way, at least the shape and configuration of the sealing surfaces  22  of the end blocks  12 A,  12 B of the seal  10  (e.g., the surface that interacts with the exemplary first side surfaces  135 ,  145  or other sealing surfaces of the exemplary first and second seal slots  170 ,  180 ) may be related to the shape and configuration of the slots  142 ,  144  in which the seal  10  is installed, and the seal may be capable of adapting (e.g., moving, deforming, flexing, etc.) to changes or variations of the shape and configuration of the slots  142 ,  144  in which the seal  10  is installed. Stated differently, seal  10  may be configured to ensure sealing engagement with the first and second seal slots  170 ,  180  in which the seal  10  is installed. For example, in the illustrated example in  FIG. 6 , the sealing surfaces  22  of the end blocks  12 A,  12 B of the seal  10  may be substantially smooth (e.g., planar) and on the same plane to substantially abut or otherwise substantially engage the substantially smooth (e.g., planar) and on-plane first side surfaces  135 ,  145  of the first and second seal slots  170 ,  180  to effectively prevent or reduce leakage of the first airflow  150  between the seal  10  and the first side surfaces  135 ,  145  of the first and second seal slots  170 ,  180  and, ultimately, into the second or hot combustion airflow  160  (and to also protect the metallic shim  16  from the high temperatures of the hot combustion airflow  160 ). In some alternative embodiments (not shown), the shape and configuration of at least the sealing surfaces  22  of the end blocks  12 A,  12 B of the seal  10  may be shaped or configured differently than that of the corresponding sealing surfaces of the first and second seal slots  170 ,  180  (such as the exemplary first side surfaces  135 ,  145  of the first and second seal slots  170 ,  180  illustrated in  FIG. 6 ). If the sealing surfaces of the first and second seal slots  170 ,  180  become misaligned or out of plane, the flexibility of the metallic shim  16  and the ceramic fiber  14  allow the end blocks  12 A,  12 B to move with respect to each other (e.g., at least in the thickness T direction) to maintain engagement of the sealing surfaces  22  with the first and second seal slots  170 ,  180  and the engagement surfaces  26  with each other to effectively prevent or reduce leakage of the first airflow  150  between the seal  10  and the first side surfaces  135 ,  145  of the first and second seal slots  170 ,  180  and, ultimately, into the second or hot combustion airflow  160 . 
       FIGS. 7-13  illustrate of another exemplary slot seal assembly  110  according to the present disclosure. The exemplary slot seal assembly  110  has some similarities to the exemplary slot seal assembly  10  of  FIGS. 1-6  described above, and therefore like reference numerals preceded with “1” are used to indicate like aspects or functions, and the description above directed to such aspects or functions (and the alternative embodiments thereof) equally applies to the exemplary slot seal assembly  110 . As shown in  FIGS. 7-13 , seal assembly  110  differs from seal  10  with respect to the configuration of the end blocks  112 A,  112 B and the engagement of the metallic shim  116  with the end blocks  112 A,  112 B. 
     In the embodiments of  FIGS. 7-13 , the engagement surfaces  126  (see  FIGS. 8-10, 12A and 12B ) of the end blocks  112 A,  112 B of the seal  110  are non-planar. The engagement surfaces  126  of the first and second end blocks  112 A,  112 B are convex and concave, respectively, in the width W direction and configured to mate or nest in abutment (e.g., are substantially mirrored shapes), as shown in  FIGS. 8-10, 12A and 12B . The engagement surface  126  of the first end block  112 A is convex in the width direction such that it defines an apex or peak positioned at about midway of the thickness T of the first end block  112 A. The engagement surface  116  of the first end block  112 A includes portions positioned above and below the apex in the thickness T direction that are planar and extend from the support surface  124  and the sealing surface  122  to the apex. Similarly, the engagement surface  126  of the second end block  112 B is concave in the width direction such that the deepest part of the concave shape in the width W direction is positioned at about midway of the thickness T of the first end block  112 A. The engagement surface  116  of the second end block  112 B includes portions positioned above and below in the thickness T direction the deepest portion of the concave shape in the width W direction that are planar and extend from the support surface  124  and the sealing surface  122  to the deepest portion of the concave shape. The convex and concave shaped engagement surfaces  126  of the end blocks  112 A,  112 B allow for the end blocks  112 A,  112 B to maintain contact or abutment under offsets (e.g., in the thickness direction) of the surfaces of the seal slot in which the seal  110  is utilized. In this way, the convex and concave shaped engagement surfaces  126  of the end blocks  112 A,  112 B prevent increases in leakage past or through the seal  10  when under offset seal slot conditions, as discussed above. 
     As also shown in  FIGS. 7-13 , the end blocks  112 A,  112 B further differ from the end blocks  12 A,  12 B in that they are void of the channels  40  on the support surfaces  124  that are open to the interior of the length L of the end blocks  112 A,  112 B in which portions of the ceramic fiber  114  and/or metallic shim  116  are positioned. Rather, the end blocks  112 A,  112 B each include or define a recessed surface, side or portion  156  that is recessed along the length L direction from the exterior or outer surfaces  132  that define the length L of the end blocks  112 A,  112 B (i.e., define the limit of the seal  10  in the length L direction). The end blocks  112 A,  112 B each include or define a ledge surface, side or portion  158  that extends from the recessed surface  156  to the exterior surface  132  of the end blocks  112 A,  112 B. In some embodiments, the ledge surface  158  and/or the recessed surface  156  are/is substantially planar. In some embodiments, the recessed surface  156  includes at least a portion that is positioned further away from the corresponding exterior surface  132  than the portion of the recessed surface  156  that is positioned at or adjacent to the support surface  124 . In some embodiments, the recessed surface  156  is positioned and/or oriented such that it is recessed an amount or distance in the length L direction from the exterior surface  132  of the end blocks  112 A,  112 B that is the same or greater than the thickness of the metallic shim  16  (and/or the ledge surface  158  extends a distance in the length L direction from the exterior surface  132  of the end blocks  112 A,  112 B to the recessed surface  156  that is the same or greater than the thickness of the metallic shim  116 ). As shown in  FIGS. 7 and 11 , the recessed surface  156  and the ledge surface  158  may cooperate to form a recess that accommodates at least one second tab portion  152  of the metallic shim  116 . The at least one second tab portion  152  of the metallic shim  116  may extend from the sealing portion  146  and extend over or past the outer edge of the ceramic fiber  114  and over or along the recessed surface  156 . In this way, the recessed surfaces  156  of the end blocks  112 A,  112 B and the at least one second tab portion  152  of the metallic shim  116  may substantially fix or couple the metallic shim  116 , the ceramic fiber  114  and the end blocks  112 A,  112 B along the length L direction. As described above with respect to the tabs  50 , the least one second tab portions  152  may be deformed or oriented in a heated state of the metallic shim  116  such that they exert a compressive force in a neutral state (i.e., at ambient temperature) of the metallic shim  116 . 
     The portions of the end blocks  112 A,  112 B proximate to the outer lateral sides or surfaces  138  may also be configured with a channel or the like  162  configured to engage with the tabs  150  of the metallic shim  116 . As shown in  FIGS. 7-10 and 12A-13 , the end blocks  112 A,  112 B may include or define a recessed lateral surface, edge or portion  160  that is positioned adjacent the support surface  124  and is recessed along the width W direction from the outer lateral sides or surfaces  138  that define the width W of the end blocks  112 A,  112 B (i.e., positioned interior in the width W direction with respect to the outer lateral sides or surfaces  138 ). The recessed lateral surface  160  may extend to a second ledge surface, side or portion  164  of the end blocks  112 A,  112 B that extends from the lateral recessed surface  160  and to the lateral side or surface  138  of the end blocks  112 A,  112 B. In some embodiments, the second ledge surface  164  may be planar and/or substantially parallel to the support surface  124  and/or the sealing surface  122 . In some embodiments, at least a portion of the lateral recessed surface  160  that is adjacent to the support surface  124  of the end blocks  112 A,  112 B may be positioned and/or oriented such that it is recessed an amount or distance in the width W direction from the lateral side or surface  138  of the end blocks  112 A,  112 B that is the same or greater than the thickness of the metallic shim  116 . 
     The lateral recessed surfaces  160  may include or define at least a portion that extends or is positioned further towards the interior of the respective end block  112 A,  112 B in the width W direction than the portion of the lateral recessed surface  160  that is adjacent the support surface  124  of the end blocks  112 A,  112 B, as shown in  FIGS. 12A and 12B . In this way, the lateral recessed surface  160 , and/or the lateral recessed surface  160  and the second ledge surface  164 , may form the channel, slot, groove or other concave form or space  164  that extends into the interior of the respective end block  112 A,  112 B in the width W direction. 
     The channels  164  may be configured to accommodate at least one tab  150  of the metallic shim  116  therein, as shown in  FIG. 7 . When the seal  110  is assembled with the ceramic fiber  114  and the metallic shim  116 , the at least one tab  150  of the metallic shim  116  may extend from the sealing portion  146  and over or past the outer later edges of the ceramic fiber  114  and over or along the lateral recessed surfaces  160  of the end blocks  112 A,  112 B, and thereby into the lateral channels  164  of the end blocks  112 A,  112 B. In this way, the lateral recessed surfaces  160  of the end blocks  112 A,  112 B and the tabs  150  of the metallic shim  116  may substantially fix or couple the metallic shim  116 , ceramic fiber  114  and the end blocks  112 A,  112 B along the width W direction. The tabs  150  of the metallic shim  116  may also extend into the channels  164  in the width W direction such that the lateral recessed surfaces  160  of the end blocks  112 A,  112 B and the tabs  150  of the metallic shim  116  may substantially fix or couple the metallic shim  116 , ceramic fiber  114  and the end blocks  112 A,  112 B along the thickness T direction. As described above, the tabs  150  of the metallic shim  116  may be deformed or oriented in a heated state of the metallic shim  116  such that they exert a compressive forced in a neutral state of the metallic shim  116 . As shown in  FIG. 7 , the metallic shim  110  may include or define a singular tab  150  on each lateral side thereof, as opposed to the plurality of distinct spaced tab  50  of the seal  10  described above. 
     The seal assemblies disclosed herein provide low leakage rate similar to that possible with tradition slot seals, such as solid metal shim seals, while eliminating the silicide formation, thermal creep and increased wear concerns when applied to modern high temperature turbomachinery (e.g., turbomachinery including CMC components). Moreover, the seal assemblies disclosed herein may be less susceptible to manufacturing variations as compared to existing seals. The seal assemblies disclosed herein thus reduce leakage with low manufacturing and operational risks, and are applicable in both OEM and retrofit applications. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Also, the term “operably connected” is used herein to refer to both connections resulting from separate, distinct components being directly or indirectly coupled and components being integrally formed (i.e., monolithic). Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. 
     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 disclosure 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. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.