A method of forming a composite article may include impregnating an inorganic fiber porous preform with a first slurry composition. The slurry composition includes particles, a solvent, and a pre-gellant material. Gelling of the pre-gellant material in the slurry composition is initiated to substantially immobilize the particles and yield a gelled article. The method also includes impregnating the gelled article with a second solution that includes a high char-yielding component, and pyrolyzing the high char-yielding component to yield carbon and form a green composite article. The green composite article is then infiltrated with a molten metal or alloy infiltrant to form the composite article. The molten infiltrant reacts with carbon, and the final composite article may include less residual metal or alloy than a composite article formed without using the second solution.

A ceramic matrix composite article includes a chemical vapor infiltration ceramic matrix composite base portion including ceramic fiber reinforcement material in a ceramic matrix material having between 0% and 5% free silicon. The ceramic matrix composite article further includes a melt infiltration ceramic matrix composite covering portion including a ceramic fiber reinforcement material in a ceramic matrix material having a greater percentage of free silicon than the chemical vapor infiltration ceramic matrix composite base portion.

A method for forming a ceramic matrix composite article includes laying up a first group of plies; laying up a second group of plies, the first and second groups of plies being adjacent to each other; compacting the first group of plies and the second group of plies in the same processing step; and performing a first infiltration process on the first group of plies. The method also includes performing a second infiltration process on the second group of plies, the first infiltration process being one of a melt infiltration process or a chemical vapor infiltration process, and the second infiltration process being the other of the melt infiltration process or the chemical vapor infiltration process.

A method of forming a composite article may include impregnating an inorganic fiber porous preform with a first slurry composition. The slurry composition includes particles, a solvent, and a pre-gellant material. Gelling of the pre-gellant material in the slurry composition is initiated to substantially immobilize the particles and yield a gelled article. The method also includes impregnating the gelled article with a second solution that includes a high char-yielding component, and pyrolyzing the high char-yielding component to yield carbon and form a green composite article. The green composite article is then infiltrated with a molten metal or alloy infiltrant to form the composite article. The molten infiltrant reacts with carbon, and the final composite article may include less residual metal or alloy than a composite article formed without using the second solution.

A method for manufacturing a magnesium-based thermoelectric conversion material of the present invention includes a raw material-forming step of forming a raw material for sintering by adding silicon oxide in an amount within a range equal to or greater than 0.5 mol % and equal to or smaller than 13.0 mol % to a magnesium-based compound, and a sintering step of heating the raw material for sintering at a temperature within a range equal to or higher than 750 C. and equal to or lower than 950 C. while applying pressure equal to or higher than 10 MPa to the raw material for sintering so as to form a sintered substance.

A ceramic matrix composite article includes a melt infiltration ceramic matrix composite substrate comprising a ceramic fiber reinforcement material in a ceramic matrix material having a first free silicon proportion, and a melt infiltration ceramic matrix composite outer layer comprising a ceramic fiber reinforcement material in a ceramic matrix material having a second free silicon proportion disposed on an outer surface of at least a portion of the substrate, or a polymer impregnation and pyrolysis ceramic matrix composite outer layer comprising a ceramic fiber reinforcement material in a ceramic matrix material having a second free silicon proportion disposed on an outer surface of at least a portion of the substrate. The second free silicon proportion is less than the first free silicon proportion.

A ceramic matrix composite article includes a melt infiltration ceramic matrix composite substrate comprising a ceramic fiber reinforcement material in a ceramic matrix material having a free silicon proportion, and a chemical vapor infiltration ceramic matrix composite outer layer comprising a ceramic fiber reinforcement material in a ceramic matrix material having essentially no free silicon proportion disposed on an outer surface of at least a portion of the substrate.

A method for making a composite material includes disposing a quantity of liquid comprising at least 90 weight percent molten boron within pores of a porous preform, the preform comprising a preform material; and reacting at least a portion of the molten boron with a portion of the preform material to form a solid ceramic reaction product, thereby forming a ceramic matrix composite material. An article comprises a composite material; the composite material comprises a fibrous phase disposed within a matrix. The matrix comprises silicon carbide, boron carbide, and boron silicide.

The invention relates to a method for producing a shaped body that contains at least 85 vol. % crystalline silicon carbide and at most 15 vol. % silicon, comprising the following steps: a) providing a powdered mixture that contains at least 60 vol. % amorphous silicon carbide and at most 40 vol. % silicon having a crystallite size of 3-50 nm; b) shaping the mixture by b1) hot pressing, or b2) compacting at room temperature and subsequent sintering or hot pressing, wherein the sintering or hot pressing is carried out in an inert gas or vacuum at a temperature of at least 1400 C. The volume ratio SiC:Si in the powdered mixture is 95:5-99:1.

A method of fabricating a ceramic material, the method including forming a ceramic material by performing a first chemical reaction at least between a first powder of an intermetallic compound and a reactive gas phase, a liquid phase being present around the grains of the first powder during the first chemical reaction, the liquid gas phase being obtained from a second powder of a metallic compound by melting the second powder or as a result of a second chemical reaction between at least one element of the first powder and at least one metallic element of the second powder, a working temperature being imposed during the formation of the ceramic material, which temperature is low enough to avoid melting the first powder.