摘要:
A pattern of depressions (36) in a sealing surface (34) on a CMC wall (32) of gas turbine ring segment (30) allows minimum clearance against turbine blades tips, and thus maximizes working gas sealing. An array of depressions (36) on the surface (34) increases abradability of the surface (34) by blade tip contact during zero clearance conditions and reduces blade tip damage. The depressions (36) are unconnected, preventing bypass of the working gas around the blade tips. A desired abradable surface geometry may be formed in a stacked laminate wall construction (40-43, 52) by staggered laminate edge profiles (50, 52) or by machining of depressions (36, 54) after construction.
摘要:
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.
摘要:
A hybrid ceramic matrix composite structure and method for fabricating such an structure are provided. A ceramic matrix composite substrate 12 includes a plurality of layers of ceramic fibers. A plurality of spaced apart imprints 22 is disposed in at least one of the plurality of layers. An outer surface of a subsequent layer disposed over the layer with the imprints to influence a texture of the outer surface of the substrate by defining a plurality of indent regions 32 on the outer surface of the substrate. A ceramic coating 14 is deposited on the surface of the substrate. The plurality of indent regions 32 constitutes a bond-enhancing arrangement between the surface of the substrate and a corresponding boundary of the coating.
摘要:
A hybrid ceramic structure and a method for protecting the hybrid ceramic structure from moisture attack in a high temperature combustion environment are provided. The structure includes a ceramic matrix composite (CMC) substrate (12). A thermal insulation material (14) is disposed on the substrate. A vapor resistant material (20) is applied through at least one surface of the hybrid ceramic structure while the hybrid ceramic structure is in a bisque condition that provides a degree of porosity to the hybrid ceramic structure so that the vapor resistant material is infiltrated through interstices available within a thickness of the hybrid ceramic structure.
摘要:
A enhanced abradable friable graded insulator FGI results from the laser patterning of a coating where a series of top surfaces reside on a series of columns such that the walls of the columns are not significantly densified relative to the interior of the columns. Patterns can be generated where the columns are oriented independently normal to or at an acute angle to the top surfaces. The cross sections of the top surfaces are formed to conform to the average dimensions of the spheres of the FGI coating. The cross sections of the top surfaces can be more than 1.5 times the diameter of the spheres. Various patterns of top surfaces can be used including regular, random, quasiperiodic patterns. A gradient of abradability can be imposed on the coating.
摘要:
A hybrid ceramic structure (10), for use in high temperature environments such as in gas turbines, is made from an insulating layer (12) of porous ceramic that is thermally stable at temperatures up to 1700° C. bonded to a high mechanical strength structural layer (8) of denser ceramic that is thermally stable at temperatures up to 1200° C., where optional high temperature resistant adhesive (9) can bond the layers together, where optional cooling ducts (11) can be present in the structural layer and where hot gas (14) can contact the insulating layer (12) and cold gas (15) can contact the structural layer (8).
摘要:
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).
摘要:
A powder-based material system having an intrinsic and stable degree of porosity provided by hollow ceramic spheres (26) in a fully dense matrix (27). A substrate (22) is formed from a metal powder (70), and may be partially sintered (60). A layer (24) of ceramic powder is arranged on the substrate including the pre-sintered hollow ceramic spheres plus a proportion of nano-sized ceramic particles effective to reduce the layer sintering temperature and to increase the sintering shrinkage of the layer to approximate that of the metal substrate during subsequent co-sintering. The substrate and layer are then co-sintered (61), such as with spark plasma sintering (32, 34, 36), at a temperature and for a duration to fully densify the ceramic powder matrix around the hollow spheres, thereby producing a metal/ceramic material system with low interface stress and with stable porosity during operational temperatures in a gas turbine engine.
摘要:
A method for joining a first CMC part (30) having an outer joining portion (32), and a second CMC part (36) having an inner joining portion (38). The second CMC part (36) is heat-cured to a stage of shrinkage more complete than that of the first CMC part (30) prior to joining. The two CMC parts (30, 36) are joined in a mating interface that captures the inner joining portion (38) within the outer joining portion (32). The assembled parts (30, 36) are then fired together, resulting in differential shrinkage that compresses the outer joining portion (32) onto the inner joining portion (38), providing a tightly pre-stressed joint. Optionally, a refractory adhesive (42) may be used in the joint. Shrinkage of the outer joining portion (32) avoids shrinkage cracks in the adhesive (42).
摘要:
A multi-wall gas turbine airfoil (192) and method of forming same using a casting core (150) having a monolithic body configured to define a pressure side wall (12), a suction side wall (14), and a third wall (16). The casting core is formed around a fugitive insert (96) during a single pour casting process.