A method of fabricating a composite material part includes injecting under pressure a slurry containing a powder of refractory ceramic particles into a fiber texture; and draining the liquid of the slurry that has passed through the fiber texture, while retaining the powder of refractory ceramic particles within the texture to obtain a fiber preform filled with refractory ceramic particles. The injection tooling includes a porous material mold including an internal housing in which the fiber texture is placed, the slurry being injected into the fiber texture via an injection port in the injection tooling and leading into the internal housing of the mold. The tooling includes a rigid material enclosure in which the porous material mold is held while the slurry is injected under pressure and while the liquid of the slurry is drained, the liquid of the slurry being discharged via a vent present in the enclosure.

A turbine assembly includes an axial turbine with an axially arranged series of rotor sections and an external sheath providing structural support for the axial turbine, wherein the sheath is made from dense silicon nitride. Each rotor section includes an outer ring and rotor blades and the outer rings of the rotor sections connect to form a rotating outer casing, wherein the rotor sections are made from reaction bonded silicon nitride.

In some examples, a method for forming an abrasive coating on a component (e.g., a turbine blade, vane, or knife ring) of a gas turbine engine. The method may include forming an abrasive coating system on a substrate, the abrasive coating system including an abrasive coating including a plurality of abrasive particles in a metal matrix; machining the abrasive coating on the substrate to define a machined abrasive coating having an abrasive coating thickness profile; and etching an outer surface of the machined abrasive coating to remove a portion of the metal matrix and form an etched metal matrix such that the abrasive particles protrude from the metal matrix.

A multilayer structure includes: a base material made of an iron-based metal material; a nitride layer that is provided on a surface of the base material through a nitriding treatment performed to the base material; an intermediate layer provided on a surface of the nitride layer; and a DLC layer provided on a surface of the intermediate layer. The intermediate layer is made of Si.sub.3N.sub.4, and the DLC layer has a thickness of 2 m to 10 m.

A method of forming a barrier layer on a ceramic matrix composite (CMC) is described. The method includes forming a particulate surface layer comprising silicon particles on an outer surface of a fiber preform. The particulate surface layer is nitrided to convert the silicon particles to silicon nitride particles. After the nitriding, the fiber preform and the particulate surface layer are infiltrated with a molten material comprising silicon. Following infiltration, the molten material is cooled, thereby forming a ceramic matrix composite with a barrier layer thereon, where the barrier layer comprises silicon nitride and less than 5 vol. % free silicon. The barrier layer may also include silicon carbide and/or one or more refractory metal silicides.

An example high-performance system may include an example high-performance component. The high-performance component may include a substrate defining a channel. The channel defines a leading ramp and a trailing ramp. The example high-performance component includes an abradable track between the leading and the trailing ramps. The abradable track includes a porous abradable composition. The example high-performance system may include a rotating component configured to contact and abrade the abradable track. An example technique for forming the abradable track includes thermal spraying a precursor composition at the channel to form the abradable track.

A method of forming an impurity barrier layer on a CMC substrate may include introducing, to a heated plume of a thermal spray gun, a composite feedstock that includes a first coating material including a plurality of first particles; and a second coating material that may be different from the first coating material, where the second coating material at least partially encapsulates at least a portion of respective surfaces of the plurality of first particles; and directing, using the heated plume, at least the first coating material to a surface of a CMC substrate to deposit an impurity barrier layer including at least the first coating material.

A gas turbine and nozzle system is provided that includes a radial inflow turbine rotor and a volute providing a flow path to deliver a pressurized gas to a circumference of the radial turbine rotor. The volute incorporates a shape which substantially conforms to a radial turbine shroud contour. The volute includes at least first and second parts. A mating surface between the first and second parts is substantially aligned with a direction of pressurized gas flow in the volute.

A gas turbine engine with a rotor having a shaft mounted to the engine with a plurality of electrically insulating bearings is provided. The electrically insulating bearings are coupled to the shaft to support the rotor in the engine. There is at least one electrically conductive bearing coupled to the shaft and that further support the rotor in the engine. An electrically conductive path is defined between the rotor and an electrical ground of the engine. The electrically conductive path is defined through the electrically conductive bearing to reach the electrical ground of the engine. A method for electrostatically discharging a rotor supported in the gas turbine engine is also provided.

Coating systems for a cooled turbine blade tip, such as a metal turbine blade tip, are provided. The coating system includes an abrasive layer overlying the surface of the turbine blade tip. One or more buffer layers may additionally be disposed between an outer surface of the blade tip and the abrasive layer. The coated blade tip can be used with a ceramic matrix composite (CMC) shroud coated with an environmental barrier coating (EBC) to provide improved cooling to the tip so as to lengthen oxidation time of the abrasive layer and reduce blade tip wear. Methods are also provided for forming the cooled blade tip and applying the coating system onto the cooled turbine blade tip.