A gas turbine engine article includes a substrate and an environmental barrier coating (EBC) system disposed on the substrate. The EBC system includes, from the substrate, a dense bond coat layer, a porous bond coat layer, and a topcoat layer in contact with the porous bond coat layer at an interface. The porous bond coat layer includes a matrix, oxygen-scavenging gas-evolution particles dispersed through the matrix, and engineered buffer pores. The oxygen-scavenging gas-evolution particles react with oxygen and generate a gaseous byproduct that diffuses through the interface to escape the EBC system. The engineered buffer pores buffer diffusion of gaseous byproduct to the interface by retaining at least a portion of the gaseous byproduct.

Disclosed is a ceramic matrix component having a fibrous core and a ceramic matrix composite shell surrounding at least a portion of the fibrous core. The ceramic matrix composite shell comprises a fibrous preform. The fibrous core has a greater porosity than the fibrous preform. A method of making the ceramic matrix component is also disclosed.

Aspects of the technology relate to a propeller blade assembly that is used in lateral propulsion systems for lighter-than-air high altitude platforms designed to operate, e.g., in the stratosphere. During operation, the propeller of the assembly is pointed along a specified heading and rotates at a selected velocity (e.g., hundreds or thousands of revolutions per minute). Power is supplied to the propeller as needed during lateral propulsion to move the platform along a particular trajectory or to remain on station over a given geographic location. In certain circumstances, the propeller may become damaged. This can include one or more blades breaking or shattering, which can result in failure of the propeller and potentially the entire LTA platform. The technology provides blades that are sufficiently flexible to avoid breakage or shattering due to debris impact or envelope entanglement, or otherwise shed a load. This can avoid catastrophic failure during stratospheric operation.

Disclosed is a method of reducing play in a vane arc segment. The vane arc segment includes an airfoil piece that defines first and second platforms and a hollow airfoil section that has an internal cavity and that extends between the first and second platforms. The first platform defines a gaspath side, a non-gaspath side, and a radial flange that projects from the non-gaspath side. Support hardware supports the airfoil piece via the radial flange, and a thermal insulation element is located adjacent the radial flange. The method includes performing a light scan of the radial flange to produce a digital three-dimensional model of the radial flange, and then machining the thermal insulation element in accordance with the digital three-dimensional model to provide a low-tolerance fit between the radial flange and the thermal insulation element that limits play between the airfoil piece and the thermal insulation element.

A turbomachine blade is made of composite material formed of woven fibers and embedded in a polymerized resin. The blade includes a root connected by a stilt to a vane which comprises a pressure side and a suction side. At least one anti-wear strip of fabric is located on a surface of the root and/or the stilt. At least one anti-wear strip is secured to the root surface in a unitary manner by the resin.

The present disclosure provides methods and systems for composite-to-metal hybrid bonded structures compromising the laser surface treatment on titanium alloys to promote adhesive bond performance. For example, a computer may be programmed to set a laser path corresponding to a predetermined geometric pattern. A laser may be coupled to the computer and apply a pulsed laser beam to a contact surface of the titanium alloy along the predefined geometric pattern. The laser may generate an open pore oxide layer on the contact surface of the substrate with a thickness of 100 and 500 nm. The open pore oxide layer may have a topography corresponding to the predefined geometric pattern. The topography may contain high degree of open pore structure and promote adhesive bond performance. Adhesive, primer or composite resin matrix may fully infiltrate into the open pore structures. Adhesive and composite laminate may co-cure to form composite-to-titanium hybrid bonded structures.

A coated component, along with methods of its formation and use, is provided. The coated component may include a substrate having a surface, a first refractory layer on the surface of the substrate, a silicon-based bond coating on the first refractory layer, and an environmental barrier coating on the silicon-based bond coating. The silicon-based bond coating includes a silicon-phase contained within a refractory phase such that, when melted, the silicon-phase is contained within the refractory phase and between the surface of the substrate and an inner surface of the environmental barrier coating.

An article may include a substrate including a ceramic or a ceramic matrix composite. The substrate defines a hot side surface configured to face a heated gas environment and a cool side surface opposite the hot side surface. The article also includes a cool side coating on the cool side surface. The cool side coating comprises at least one material having a flow temperature equal to or slightly less than a temperature of the heated gas environment.

A method for forming a ceramic matrix composite (CMC) component with an internal cooling channel includes partially densifying a first fiber preform to form a portion of a final ceramic matrix volume, machining a first channel into a surface of the partially densified first fiber preform, covering the first channel with a fibrous member to form a near net shape fiber preform with an internal passage formed by the first channel and the fibrous member, and densifying the near net shape fiber preform.

A turbine stator blade made of ceramic matrix composite material includes a hollow blade profile and has a trailing edge and a leading edge, the blade including a first portion including an extrados face and a second portion distinct from the first portion including an intrados face, the first and second portions being connected to one another by a connection interface present at least on the trailing edge or leading edge, the connecting interface including a region of overlap between the first and second portions present on at least one longitudinal end of the blade profile and intended to be present outside a flow path of a gas stream of the turbine, the blade also including a platform present at a longitudinal end of the blade profile and that includes a first portion integral with the extrados face and a second part integral with the intrados face.