A fiber comprises a bulk material comprising one or more materials selected from the group consisting of carbon, silicon, boron, silicon carbide, and boron nitride; and a metal whose affinity for oxygen is greater than the affinity for oxygen of any of the one or more materials. The metal may be selected from the group consisting of beryllium, titanium, hafnium and zirconium. At least a first portion of the metal may be present in un-oxidized form at the entrance to and/or within grain boundaries within the fiber. A method of improving at least one of the strength, creep resistance, and toughness of a fiber comprises adding to a fiber, initially comprising a bulk material having a first affinity for oxygen, a metal that has a second affinity for oxygen higher than the first affinity. The metal may be selected from the group consisting of beryllium, titanium, hafnium and zirconium.

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 of fabricating a part out of ceramic matrix composite material, the method including infiltrating a fiber preform with a molten composition including a majority by weight of silicon, the fiber preform including silicon carbide fibers, silicon carbide powder being present in the pores of said preform, a mean size of silicon carbide crystallites in the powder being less than the mean size of the silicon carbide crystallites in the fibers, a ceramic matrix being formed in the pores of the fiber preform during the infiltration so as to obtain the part made of composite material.

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.

Methods for preparing ceramic matrix composites using melt infiltration and chemical vapor infiltration are provided as well as the resulting ceramic matrix composites. The methods and products include the incorporation of sacrificial fibers to provide improved infiltration of the fluid infiltrant. The sacrificial fibers are removed, such as decomposed during pyrolysis, resulting in the formation of regular and elongate channels throughout the ceramic matrix composite. Infiltration of the fluid infiltrant can then take place using the elongate channels resulting in improved density and an improved ceramic matrix composite product.

A method of fabricating a part out of ceramic matrix composite material, the method including infiltrating a fiber preform with a molten composition including a majority by weight of silicon, the fiber preform including silicon carbide fibers, silicon carbide powder being present in the pores of said preform, a mean size of silicon carbide crystallites in the powder being less than the mean size of the silicon carbide crystallites in the fibers, a ceramic matrix being formed in the pores of the fiber preform during the infiltration so as to obtain the part made of composite material.

The present invention relates to a method of printing a composite material (1), for example polymeric, carbonaceous, siliconic or metallic comprising steps of: i) providing a plurality of bundles (2) of reinforcement fibers (4), wherein the reinforcement fibers (4) have a length in the range 3-50 mm and are in the number of about 1,000-100,000 in each bundle (2); ii) aligning the bundles (2) along a predetermined path (X, X); iii) incorporating at least part of the bundles (2) into a matrix (6, 8), for example polymeric, carbonaceous, siliconic or metallic, preserving the alignment along said path (X, X); iv) laying and solidifying at least one layer (8) of the matrix (6, 8) of step iii) to make the composite material (1).

Disclosed is a multi nanolayer interface coating for a fiber of a composite including a first interface coating nanolayer deposited onto the fiber of the ceramic matrix composite, and a second interface coating nanolayer deposited onto the first interface coating nanolayer.

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 method of forming a ceramic matrix composite (CMC) component having an engineered surface includes applying a surface slurry comprising first particulate solids in a liquid carrier to an outer surface of a ceramic fiber preform. The surface slurry is dried to remove the liquid carrier, and thus a surface slurry layer comprising the first particulate solids is formed on the outer surface. The surface slurry layer is polished to a predetermined thickness and/or surface finish. After polishing, a ceramic tape comprising second particulate solids is applied to the surface slurry layer, and pressure is applied to attach the ceramic tape to the surface slurry layer and to induce consolidation of the ceramic tape and the surface slurry layer. Thus, a multilayer surface region comprising the surface slurry layer and a ceramic tape layer is formed on the ceramic fiber preform. The ceramic fiber preform and the multilayer surface region are infiltrated with a molten material, and, upon cooling, a CMC component having an engineered surface is formed.