Rolls-Royce High Temperature Composites Inc.

A method of making a ceramic matrix composite includes infiltrating a fiber preform comprising silicon carbide fibers with a slurry comprising a liquid, silicon carbide particles, carbon particles, and silicon particles to form a slurry-infiltrated fiber preform. The slurry-infiltrated fiber preform is infiltrated with a molten material comprising silicon. Prior to or during the infiltration with the molten material, the silicon particles are melted. The molten material is cooled, and a ceramic matrix composite including a ceramic matrix reinforced with the silicon carbide fibers is formed, where the ceramic matrix is substantially devoid of dry slurry defects.

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 assembly for nuclear applications includes a tubular cladding for containing nuclear fuel. The tubular cladding comprises a ceramic matrix composite. An assembly tube surrounds the tubular cladding, and a collar is positioned between the tubular cladding and the assembly tube. The collar extends circumferentially around the cladding and comprises the ceramic matrix composite. The tubular cladding may be centered within the assembly tube by the collar.

A high temperature vessel includes a structure and a coating. The structure defines a cavity and an interior surface lining the cavity, and includes graphite at the interior surface. The coating overlies at least a portion of the interior surface and defines a contact surface configured to contact molten silicon. The coating includes at least one of silicon carbide or boron carbide, and is deposited via at least one of chemical vapor deposition or chemical vapor infiltration.

A method of making a ceramic matrix composite (CMC) having an increased carbon content that may show improved resistance to chemical attack from molten silicon is described. The method includes depositing one or more matrix layers comprising boron nitride, silicon nitride, pyrolytic carbon, and/or silicon carbide on a fiber preform comprising one or more silicon carbide fibers. After depositing the matrix layer, the fiber preform is dipped into a coating solution comprising a polymer to deposit a polymeric layer on the matrix layer. After dip coating, the fiber preform is infiltrated with a slurry comprising ceramic particles and/or carbon particles to form a green body; after forming the green body, the polymeric layer is pyrolyzed to form a carbon-containing coating on the matrix layer; and the green body is then infiltrated with a melt comprising silicon or silicon alloy. Upon cooling the melt, a dense CMC formed may be obtained.

An exhaust trap configured to filter an exhaust stream of a vacuum furnace may include a housing and a media barrier. The housing defines an interior. The media barrier may divide the interior of the housing into a first chamber and a second chamber and is configured to allow the exhaust stream to flow from the first chamber to the second chamber. The exhaust trap may further include a filter medium in the first chamber and configured to filter the exhaust stream. No filter medium is present in the second chamber.

A turbine shroud assembly adapted for use with a gas turbine engine includes a shroud segment. The shroud segment includes a heat shield, an attachment flange, and a multi-layer coating. The heat shield extends circumferentially partway around the axis to define a portion of gas path for the gas turbine engine. The attachment feature extends radially outward from the heat shield. The multi-layer coating is applied to different surfaces of the heat shield and the attachment feature of the shroud segment.

A test apparatus for a ceramic matrix composite (CMC) component. The test apparatus includes a first support member configured to mechanically support a CMC component from a first side. The CMC component includes a T-joint and a pinhole. The test apparatus includes a second support member configured to mechanically support the CMC component from a second side opposite the first side. The first support member and the second support member are configured to be forced toward each other to cause the CMC component to fail at the pinhole and not at the T-joint.

A method to form a machinable ceramic matrix composite comprises forming a porous ceramic multilayer on a surface of a fiber preform. In one example, the porous ceramic multilayer comprises a gradient in porosity in a direction normal to the surface. In another example, the porous ceramic multilayer includes low-wettability particles having a high contact angle with molten silicon, where an amount of the low-wettability particles in the porous ceramic multilayer varies in a direction normal to the surface. After forming the multilayer, the fiber preform is infiltrated with a melt, and the melt is cooled to form a ceramic matrix composite with a surface coating thereon. An outer portion of the surface coating is machined to form a ceramic matrix composite having a machined surface with a predetermined surface finish and/or dimensional tolerance.

An assembly for nuclear applications includes a tubular cladding for containing nuclear fuel. The tubular cladding comprises a ceramic matrix composite. An assembly tube surrounds the tubular cladding, and a collar is positioned between the tubular cladding and the assembly tube. The collar extends circumferentially around the cladding and comprises the ceramic matrix composite. The tubular cladding may be centered within the assembly tube by the collar.