Abstract: A hybrid ceramic matrix composite (CMC) structure 10 and method for fabricating such an structure are provided. A CMC substrate 12 includes layers 16, 18, 20 of ceramic fibers. Fugitive objects 22 are disposed on at least one of the plurality of layers prior to laying a subsequent layer of ceramic fibers. An outer surface of the subsequent layer influences a shape of the outer surface of the substrate by defining protuberances 24 on the outer surface of the substrate where respective cavities 26 are formed beneath respective protuberances upon dissipation of the fugitives. A liquefied ceramic coating 34 is deposited on the outer surface of the ceramic substrate to fill the cavities. When the ceramic coating is cured to a solidified state, the cavities containing the solidified coating constitute an anchoring arrangement between the ceramic substrate and the ceramic coating.

Abstract: A stack of substantially parallel ceramic plates (22) separated and interconnected by ceramic spacers (26, 27) forming a seal structure (20) with a length (L), a width (W), and a thickness (T). The spacers are narrower in width than the plates, and may be laterally offset from spacers in adjacent rows to form a space (28) in a row that aligns with a spacer in another adjacent row. An adjacent plate bends into the space when the seal structure is compressed in thickness. The spacers may have gaps (60, 62) forming a stepped or labyrinthine cooling flow path (66) within the seal structure. The spacers of each row may vary in lateral separation, thus providing a range of compressibility that varies along the width of the seal structure.

Abstract: A turbine vane assembly includes an airfoil extending between an inner shroud and an outer shroud. The airfoil can include a substructure having an outer peripheral surface. At least a portion of the outer peripheral surface is covered by an external skin. The external skin can be made of a high temperature capable material, such as oxide dispersion strengthened alloys, intermetallic alloys, ceramic matrix composites or refractory alloys. The external skin can be formed, and the airfoil can be subsequently bi-cast around or onto the skin. The skin and the substructure can be attached by a plurality of attachment members extending between the skin and the substructure. The skin can be spaced from the outer peripheral surface of the substructure such that a cavity is formed therebetween. Coolant can be supplied to the cavity. Skins can also be applied to the gas path faces of the inner and outer shrouds.

Abstract: A ceramic matrix composite (CMC) component such as a ring seal segment (50, 50A, 50B, 50C, 50D) for a gas turbine engine (10), the component formed with a base plate (52) and a frame portion (54) that extends substantially normally from the base plate around its perimeter. A grid of intersecting CMC ribs (73) is formed on the base plate within the frame portion. The ribs have a height (H) that may be within 3 times the total thickness (B) of the base plate, including any rib base (39) bonded to the base plate, along at least most of the rib length. The grid of ribs may be assembled from an array of CMC cups (40) bonded to the base plate, to adjacent cups, and to the frame portion.

Abstract: Structural arrangements and methodology are provided for strengthening a bond between corresponding surfaces of a thermally insulating ceramic coating (14) and a ceramic matrix composite substrate (12). A subsurface inclusion of spheroid objects allows to influence a texture of an outer surface of the CMC substrate to enhance the bonding characteristics between the corresponding surfaces.

Abstract: A ceramic matrix composite (CMC) structure and methods of fabricating such structure are disclosed. In one example, the surface of a CMC substrate (12) is urged against a surface of a tool having blunt teeth. The blunt teeth can form surface indents that can serve as a first bond-enhancing arrangement between the surface of the substrate and a corresponding boundary of a thermally-insulating coating (14). In another example, sharp teeth can form surface indents and also penetrate through the surface of the substrate to cut some of the fibers beneath the surface of the substrate into split fiber segments, and a portion of the split fiber segments can protrude above the surface of the substrate. The protruding fiber segments can serve as a second bond-enhancing arrangement between the surface of the substrate and the corresponding boundary of the coating.

Abstract: A method for forming interphase layers in ceramic matrix composites. The method forms interphase layers in ceramic matrix composites thereby enabling higher matrix densities to be achieved without sacrificing crack deflection and/or toughness. The methods of the present invention involve the use fugitive material-coated fibers. These fibers are then infiltrated with a ceramic matrix slurry. Then, the fugitive material is removed and the resulting material is reinfiltrated with an interphase layer material. The ceramic matrix composite is then fired. Additional steps may be included to densify the ceramic matrix or to increase the strength of the interphase layer. The method is useful for the formation of three dimensional fiber-reinforced ceramic matrix composites envisioned for use in gas turbine components.

Abstract: A stitching geometry and method for selective interlaminar reinforcement of a CMC wall (20A). The CMC wall is formed of ceramic fiber layers (22) individually infused with a ceramic matrix, stacked, and at least partially cured. A row of holes is formed in the wall, and a ceramic fiber thread (25) is infused with a wet ceramic matrix and passed through the holes to form stitches (28, 30, 31). The stitches are then cured, causing them to shrink more than any remaining wall shrinkage, thus tensioning the stitches and compressing the wall laminae together. The stitches may have through-wall portions (30, 31) that are angled differently in different wall areas as a function of interlaminar shear over interlaminar tension, optimizing wall reinforcement locally depending on magnitude and direction of shear. Alternate rows of stitches (54, 56) may have offsets in a stitch direction (34) and/or different through-wall angles (A1, A2).

Abstract: A CMC wall (22) with a front surface (21) heated (24) by a working fluid in a gas turbine. A back CMC surface (23) is coated with a layer (42) of a thermally conductive material to accelerate heat transfer in the plane of the CMC wall (22), reducing thermal gradients (32-40) on the back CMC surface (23) caused by cold spots (32) resulting from impingement cooling flows (26). The conductive material (42) may have a coefficient of thermal conductivity at least 10 times greater than that of the CMC material (22), to provide a minimal thickness conductive layer (42). This reduces thermal gradient stresses within the CMC material (22), and minimizes differential thermal expansion stresses between the CMC material (22) and the thin conductive layer (42).

Abstract: Aspects of the invention are directed to a gas turbine component such as a ring seal segment or combustor heat shield having a base and a plurality of walls defining a volume. The base and the walls are independently formed and are formed from ceramic matrix composite plates. The base and walls can have interconnection structures that allow for assembly. The base and walls can be coated or otherwise wrapped for connection. Locking mechanisms, such as self locking lugs, can be used for assembly.

Abstract: A method for forming interphase layers in ceramic matrix composites. The method forms interphase layers in ceramic matrix composites thereby enabling higher matrix densities to be achieved without sacrificing crack deflection and/or toughness. The methods of the present invention involve the use fugitive material-coated fibers. These fibers are then infiltrated with a ceramic matrix slurry. Then, the fugitive material is removed and the resulting material is reinfiltrated with an interphase layer material. The ceramic matrix composite is then fired. Additional steps may be included to densify the ceramic matrix or to increase the strength of the interphase layer. The method is useful for the formation of three dimensional fiber-reinforced ceramic matrix composites envisioned for use in gas turbine components.

Abstract: An apparatus for a gas turbine engine, such as a transition (225, 325), includes a metal shell (200, 300) surrounding a body (230, 330) that is comprised of a ceramic matrix composite (CMC)-comprising structure (231) and a ceramic insulating layer (265) bonded thereto. The metal shell (200, 300) defines a space (250) adapted to contain the transition body (230, 330), and comprises at least one protrusion (220) adapted to contact the transition body (230, 330). A pin (255) passes through the transition body (230, 330) and the metal shell (200, 300) at their forward ends, and a compliant porous element (240) is adapted to fit in the space (250) between the metal shell (200, 300) and the transition body (230, 330).

Abstract: A CMC airfoil (20) formed with CMC stitches (37) interconnected between opposed walls (26, 28) of the airfoil to restrain outward flexing of the walls resulting from pressurized cooling air within the airfoil. The airfoil may be formed of a ceramic fabric infused with a ceramic matrix and dried, and may be partially to fully cured. Then holes (32, 34) are formed in the opposed walls of the airfoil, and a ceramic stitching element such as ceramic fibers (36) or a ceramic tube (44) is threaded through the holes. The stitching element is infused with a wet ceramic matrix before or after threading, and is flared (38) or otherwise anchored to the walls (26, 28) to form a stitch (37) there between. The airfoil and stitch are then cured. If the airfoil is cured before stitching, a pre-tension is formed in the stitch due to relative curing shrinkage.

Abstract: A structure for use in high temperature applications is provided. The structure may include an inner ceramic matrix composite (CMC) material (12). At least a portion of this CMC material includes waves that define a first wavy surface (140 and an opposed second wavy surface (16). A ceramic insulation material (18) may be bonded with the first wavy surface and includes a distal surface (20) for exposure to a high temperature environment. A core material (22) is bonded with at least a portion of the second wavy surface. One or more cooling channels (24) are disposed in the core material. An outer CMC material (26) may be joined to a portion of the inner CMC material. The core material is a material different than a matrix material of the inner CMC material.

Abstract: A CMC wall (22) with a front surface (21) heated (24) by a working fluid in a gas turbine. A back CMC surface (23) is coated with a layer (42) of a thermally conductive material to accelerate heat transfer in the plane of the CMC wall (22), reducing thermal gradients (32-40) on the back CMC surface (23) caused by cold spots (32) resulting from impingement cooling flows (26). The conductive material (42) may have a coefficient of thermal conductivity at least 10 times greater than that of the CMC material (22), to provide a minimal thickness conductive layer (42). This reduces thermal gradient stresses within the CMC material (22), and minimizes differential thermal expansion stresses between the CMC material (22) and the thin conductive layer (42).

Abstract: A method of making a combustion turbine component includes assembling a plurality of metallic combustion turbine subcomponent greenbodies together to form a metallic greenbody assembly and sintering the metallic greenbody assembly to thereby form the combustion turbine component. Each of the plurality of metallic combustion turbine subcomponent greenbodies may be formed by direct metal fabrication (DMF). In addition, each of plurality of metallic combustion turbine subcomponent greenbodies may include an activatable binder and the activatable binder may be activated prior to sintering.

Abstract: A method of forming a ceramic matrix composite (CMC) article (30) or a composite article (60) that minimizes the risk of delaminations while simultaneously maintaining a desired degree of porosity in the material. A pressure P applied against a surface of the article during a sintering process is controlled to be high enough to resist a separation force between the plies (66) of the CMC material (62) caused by anisotropic shrinkage of the material and/or to resist a separation force caused by differential shrinkage between the CMC material and an adjoined monolithic ceramic material (64). The pressure is also controlled to be low enough to avoid undue consolidation of the materials and to provide a desired degree of porosity in the sintered article. The pressure may be applied by delta-alpha tooling, and it may be varied verses the time of the sintering heating and/or across the article surface.

Abstract: A ceramic hybrid structure (207, 502, 602, 608) that includes a wavy ceramic matrix composite (CMC) wall (214, 532, 603, 609) bonded with a ceramic insulating layer (230, 538, 604, 610) having a distal surface (242) that may define a hot gas passage (250, 550, 650) or otherwise be in proximity to a source of elevated temperature. In various embodiments, the waves (216, 537, 637) of the CMC wall (214, 532, 603, 609) may conform to the following parameters: a thickness (222) between 1 and 10 millimeters; an amplitude (224) between one and 2.5 times the thickness; and a period (226) between one and 20 times the amplitude. The uninsulated backside surface (218) of the CMC wall (214) provides a desired stiffness and strength and enhanced cooling surface area. In various embodiments the amplitude (224), excluding the thickness (222), may be at least 2 mm.

Abstract: An attachment method and flange for connecting a ceramic matrix composite (CMC) component, such as a gas turbine shroud ring (36, 68), to a metal support structure. A CMC flange (20A) may be formed by attaching a wedge-shaped block (26) of a ceramic material to a CMC wall structure (22), and wrapping CMC layers (24) of the wall structure (22) at least partly around the block (26), forming the flange (20A) with an inner oblique face (34) and an outer face (35) normal to the wall structure. An adjacent support structure, such as a metal support ring (40A), may abut the outer face (35) of the CMC flange (20A) and be clamped or bolted to the CMC flange (20A).

Abstract: A gas turbine component (20) with a layer of ceramic material (22) defining a wear surface (21), in which an array of cross-shaped depressions (26A, 26B) formed in the wear surface (21) define a continuous labyrinth of orthogonal walls (28, 30) of the ceramic material, and reduce the area of the wear surface (21) by about 50%. Within a representative area (36) of the wear surface (21), the depressions (26A, 26B) provide a ratio of a lineal sum of depression perimeters (27) divided by the representative area (36) of the wear surface of least 0.9 per unit of measurement for improved abradability characteristics of the wear surface (21).