A ceramic matrix composite (CMC) is formed by infiltrating a metal or alloy into a fiber preform in a reactor or furnace that is separated into multiple discrete temperature zones. The gradual cooling of the CMC is controlled, such that upon solidification, a narrow, planar, solidification front is created which allows the expanding metal or alloy to move into a hotter section of the fiber preform, opposed to the surface of the CMC. A discrete solidification front is established that moves through the ceramic matrix composite (CMC) as the composite cools.

A fiber reinforced composite component may include interleaved textile layers and ceramic particle layers coated with matrix material. The fiber reinforced composite component may be fabricated by forming a fibrous preform and densifying the fibrous preform. The fibrous preform may be fabricated by forming a first ceramic particle layer over a first textile layer, disposing a second textile layer over the first ceramic particle layer, forming a second ceramic particle layer over the second textile layer, and disposing a third textile layer over the second ceramic particle layer.

A ceramic component is formed of at least one stack of two or more layers of one-directional non-woven carbon fiber fabrics embedded in a ceramic matrix containing silicon carbide and elemental silicon. All adjacent layers within the at least one stack directly adjoin each other. The at least one stack has a minimum thickness of 1.5 mm perpendicularly to the plane of the layers. The ceramic matrix permeates substantially the entire component.

The method may include forming fibers with a silicon-based sizing, forming a fibrous preform from the fibers, forming a silicon dioxide coating around the fibers, carbonizing the fibrous preform, and densifying the fibrous preform. In various embodiments, forming the fibers with the silicon-based sizing includes utilizing a mass of the silicon-based sizing that is at least 1.0% of a mass of the fibers.

A nanocomposite optical ceramic (NCOC) material includes a plurality of coated (core-shell) nanoparticles having nanoparticles of a first material coated with a coating of a second material. The first material and the second material are mutually insoluble and each have a transmissivity of at least 80% for an intended wavelength. The first material and the second material have a difference in index of refraction of less than 25%. The first material and second material have grins with a diameter of less than 1/20.sup.th the intended wavelength. The coating of the second material on the nanoparticles of the first material is up to 50 nm thick. The NCOC contains no more than 0.01% voids per unit volume.

A method for manufacturing a resonator in a substrate, including: a) modifying a structure of at least one region of the substrate to make the at least one region more selective; b) etching the at least one region to selectively manufacture the resonator.

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.

An abradable coating includes a tubular cell structure, wherein the the tubular cell structure includes a fibrous reinforcement of discontinuous short fibers which is densified by a ceramic matrix.

A method for coating a fiber tow includes moving a fiber tow across a wedge to separate the fiber tow into a plurality of sub-tows, and coating the plurality of sub-tows.

A fiber reinforced composite component may include interleaved textile layers and ceramic particle layers coated with matrix material. The fiber reinforced composite component may be fabricated by forming a fibrous preform and densifying the fibrous preform. The fibrous preform may be fabricated by performing a silicon melt infiltration after the densification process. A plurality of pores defined by the carbon matrix material are infiltrated with a silicon material and the fibrous preform is heated to a melt temperature until a desired percentage (e.g., at least 50%) of the carbon matrix material is converted into silicon carbide or another oxidation resistant material.