Disclosed herein is a chemical vapor infiltration method including flowing ceramic precursors through a preform and depositing a matrix material on the preform at a first gas infiltration pressure, increasing the gas filtration pressure to a second gas infiltration pressure, and lowering the gas infiltration pressure to a third gas infiltration pressure which is intermediate to the first and second gas infiltration pressures.

A full-fiber burner brick and a preparation method thereof, comprising mixing alumina crystal fiber and amorphous ceramic fiber with both of them being a combination of fibers of different lengths gradations, and moreover adding fine powder fillers of different particle size gradations and supplementing other additives. This enables the internal structure of the product more uniform, increases the bulk density of the product, and also benefits the suction filterability of fiber cotton blank, and is conducive to forming and improving the strength of the blank. The surface of the brick body is further provided with a coating, which can effectively protect the cotton fiber of the brick body fiber from harsh environments, improve its high temperature resistance, and help to extend the service life of the burner brick.

A method for constructing multiple ceramic layers by winding continuous ceramic filaments of identical composition to prepare multilayer RF-transparent structures is provided. In the method, identical continuous ceramic filaments are wound to construct a layer with specific dielectric constant according to patterns, characterized by the winding angle, winding density/inter-fiber aperture and winding count/layer thickness. Layers with same or different dielectric characteristics forms a sandwich design to fulfill the desired mechanical, thermal and electrical requirements.

Disclosed is a method of coating a high temperature fiber including depositing a base material on the high temperature fiber using atomic layer deposition, depositing an intermediate material precursor on the base material using molecular layer deposition, depositing a top material on the intermediate material precursor or the intermediate layer using atomic layer deposition, and heat treating the intermediate precursor. The intermediate material in the final coating includes a structural defect, has lower density than the top material or a combination thereof. Also disclosed are the coated high temperature fiber and a composite including the high temperature fiber.

A method for making a ceramic matrix composite component includes densifying a fibrous preform of the component with a ceramic matrix to form an intermediate component; infiltrating a hole in the intermediate component with an infiltrate material comprising a solid and a metallic alloy whose reaction forms a carbide, silicide, boride or combination thereof, heating the infiltrate material to a temperature in excess of a melting point of the metallic alloy; and sequentially cooling regions of the hole starting from an interior end of the hole to the outer surface of the intermediate component to form a solidified through-thickness reinforcement element. The hole extends in a through-thickness direction and is open to an exterior surface of the intermediate component.

The present invention discloses an Al.sub.2O.sub.3-based ceramic welding sealing component and a preparation method thereof, and relates to the technical field of metalized ceramic processing. The Al.sub.2O.sub.3-based ceramic welding sealing component disclosed in the present invention comprises a ceramic matrix and a metallized layer. The ceramic matrix is made from raw materials such as an inorganic fiber-aluminum oxide 3D network matrix, yttrium oxide, silicon oxide, titanium oxide, an additive, a binder and a dispersant, through steps such as preparation of the inorganic fiber-aluminum oxide 3D network matrix, mixing, pelletizing, primary sintering and secondary sintering; and the raw materials of the metallized layer comprise titanium powder, tungsten powder, molybdenum oxide, boron oxide, yttrium oxide and an organic binder. Al.sub.2O.sub.3-based ceramic welding sealing component provided by the present invention has high efficiency of space filling and tensile strength, excellent tensile strength, toughness and high-temperature resistance.

A method for forming ceramic matrix composite (CMC) component includes forming a fiber preform, positioning the fiber preform into a chemical vapor infiltration reactor chamber, and densifying the fiber preform. Densification includes infiltrating the fiber preform with a first gas comprising precursors of silicon carbide and infiltrating the fiber preform with a second gas comprising a first rare earth element, wherein the steps of infiltrating the fiber preform with the first gas and infiltrating the fiber preform with the second gas are conducted simultaneously to produce a first rare earth-doped silicon carbide matrix in a first region of the component.

A method for delivering a flowable material into a mold or to infiltrate a preformed component, a fiber preform, or a green body includes: providing a crucible having a body configured as a reservoir to hold the flowable material; adding a metal, a metal alloy, or combination thereof into the body of the crucible, the metal or metal alloy having a predetermined melting point; heating the crucible with the metal or metal alloy contained therein to a temperature that is at or above the melting point of the metal or metal alloy; allowing the metal or metal alloy to melt to form the flowable material; and creating a siphon such that the molten metal or metal alloy flows from the body of the crucible to infiltrate the preformed component or to fill the mold.

This invention provides resin formulations which may be used for 3D printing and pyrolyzing to produce a ceramic matrix composite. The resin formulations contain a solid-phase filler, to provide high thermal stability and mechanical strength (e.g., fracture toughness) in the final ceramic material. The invention provides direct, free-form 3D printing of a preceramic polymer loaded with a solid-phase filler, followed by converting the preceramic polymer to a 3D-printed ceramic matrix composite with potentially complex 3D shapes or in the form of large parts. Other variations provide active solid-phase functional additives as solid-phase fillers, to perform or enhance at least one chemical, physical, mechanical, or electrical function within the ceramic structure as it is being formed as well as in the final structure. Solid-phase functional additives actively improve the final ceramic structure through one or more changes actively induced by the additives during pyrolysis or other thermal treatment.

A prepreg including a support with, for more than 90% of the weight thereof, of ceramic fibers, and a thermoreversible liquefiable gel covering, at least in part, at least one portion of the ceramic fibers. The liquefiable gel including: 20% to 60% of ceramic particles and 0% to 10% of metal particles, both as percentage by volume based on the volume of the liquefiable gel; 0.2% to 10% of a thermoreversible hydrocolloid and 0% to 7% of one or more other constituents, both as a percentage by weight on the basis of the total weight of the ceramic particles and metal particles; the balance to 100% being water. It being possible for the ceramic particles and the metal particles to be replaced, partially or completely, by precursors of ceramic particles and of metal particles, respectively, capable of forming, by heat treatment above 200° C., ceramic particles and metal particles, respectively.