In some examples, an article for a high-temperature mechanical system including a substrate and a doped calcia-magnesia-alumina-silicate resistant (doped CMAS-resistant) layer on the substrate. The doped CMAS-resistant layer is a thermal barrier coating or an environmental barrier coating and includes a calcia dopant.

A method makes a silicon compound-based passivating coating on a ceramic matrix composite reinforced with carbon fibers. A piece made in a ceramic matrix composite reinforced with carbon fibers is placed in a closed chamber of an oven. A predefined load of solid silicon is placed in the chamber avoiding direct contact between the silicon and the piece. The oven is heated while maintaining inside the chamber predefined medium/low vacuum conditions, to generate silicon vapors inside the chamber. The vapors react with substances on the surface of the piece to form a surface coating having composites of the substances with the silicon. The partial pressure of the vacuum, temperature inside the chamber and exposure times of the piece to the silicon vapors to obtain a predefined thickness of the surface coating are chosen. The piece is cooled once the predefined thickness of the passivating coating is reached.

A method makes a silicon compound-based passivating coating on a ceramic matrix composite reinforced with carbon fibers. A piece made in a ceramic matrix composite reinforced with carbon fibers is placed in a closed chamber of an oven. A predefined load of solid silicon is placed in the chamber avoiding direct contact between the silicon and the piece. The oven is heated while maintaining inside the chamber predefined medium/low vacuum conditions, to generate silicon vapors inside the chamber. The vapors react with substances on the surface of the piece to form a surface coating having composites of the substances with the silicon. The partial pressure of the vacuum, temperature inside the chamber and exposure times of the piece to the silicon vapors to obtain a predefined thickness of the surface coating are chosen. The piece is cooled once the predefined thickness of the passivating coating is reached.

A coated component, along with methods of its formation, are provided. The coated component may include a ceramic matrix composite substrate comprising silicon carbide and having a surface, a bond coat on the surface of the substrate, and an environmental barrier coating on the bond coat. The bond coat includes a plurality of discrete particles dispersed within a matrix phase, with the matrix phase formed from mullite and defining 60% to 98% by volume of the bond coat. The plurality of discrete particles include an oxygen getter and has 50% of its volume or greater formed from particles having an average size of 10 μm to 100 μm.

A coated component, along with methods of its formation, are provided. The coated component may include a ceramic matrix composite substrate comprising silicon carbide and having a surface, a bond coat on the surface of the substrate, and an environmental barrier coating on the bond coat. The bond coat includes a plurality of discrete particles dispersed within a matrix phase, with the matrix phase formed from mullite and defining 60% to 98% by volume of the bond coat. The plurality of discrete particles include an oxygen getter and has 50% of its volume or greater formed from particles having an average size of 10 μm to 100 μm.

An aerospace component may comprise a fiber reinforced composite material. The fiber reinforced composite material includes a plurality of fiber layers and a carbon matrix surrounding the plurality of fiber layers. A plurality of ceramic particles is dispersed in the carbon matrix. A first fiber layer of the plurality of fiber layers may include a carbon fiber, and a second fiber layer of the plurality of fiber layers may include a non-carbon fiber. A hardness of the non-carbon fiber is greater than a hardness of carbon fiber.

The present invention describes various methods for manufacturing gel composite sheets using segmented fiber or foam reinforcements and gel precursors. Additionally, rigid panels manufactured from the resulting gel composites are also described. The gel composites are relatively flexible enough to be wound and when unwound, can be stretched flat and made into rigid panels using adhesives.

Nuclear fuel structures and methods for fabricating are disclosed herein. The nuclear fuel structure includes a plurality of fibers arranged in the structure and a multilayer fuel region within at least one fiber of the plurality of fibers. The multilayer fuel region includes an inner layer region made of a nuclear fuel material, and an outer layer region encasing the nuclear fuel material. A plurality of discrete multilayer fuel regions may be formed over a core region along the at least one fiber, the plurality of discrete multilayer fuel regions having a respective inner layer region of nuclear fuel material and a respective outer layer region encasing the nuclear fuel material. The plurality of fibers may be wrapped around an inner rod or tube structure or inside an outer tube structure of the nuclear fuel structure, providing both structural support and the nuclear fuel material of the nuclear fuel structure.

Nuclear fuel structures and methods for fabricating are disclosed herein. The nuclear fuel structure includes a plurality of fibers arranged in the structure and a multilayer fuel region within at least one fiber of the plurality of fibers. The multilayer fuel region includes an inner layer region made of a nuclear fuel material, and an outer layer region encasing the nuclear fuel material. A plurality of discrete multilayer fuel regions may be formed over a core region along the at least one fiber, the plurality of discrete multilayer fuel regions having a respective inner layer region of nuclear fuel material and a respective outer layer region encasing the nuclear fuel material. The plurality of fibers may be wrapped around an inner rod or tube structure or inside an outer tube structure of the nuclear fuel structure, providing both structural support and the nuclear fuel material of the nuclear fuel structure.

A method is provided for calculating gaseous diffusion and oxidation evolution of a ceramic matrix composite (CMC) structure, which includes determining temperature and load distribution in a structural member; determining matrix crack distribution in the structure; establishing an equivalent diffusion coefficient model of a fiber bundle scale to predict a gas flow channel in a fiber bundle: averaging a total amount of gaseous diffusion in the channel to establish the equivalent diffusion coefficient model of the fiber bundle composite scale related to the matrix crack distribution; establishing a representative volume element (RVE) model; establishing an equivalent diffusion coefficient model of a RVE scale; calculating the distribution of the gas concentration and oxidation products in the structure; calculating a growth thickness of an oxide at cracks and pores in each element; and updating sealing conditions of the gas channel, and calculating a new equivalent diffusion coefficient field and the distribution of the oxidation products again.