Abstract: 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.

Abstract: Methods for preparing ceramic products using liquid infusion technology and products formed from the same are provided. The methods and products include the incorporation of a particulate material and binder between ceramic fibers such that the fibers may be properly spaced during formation of the ceramic product. Ceramic matrix composite products can thereby be provided using near net shaping methods.

Abstract: A method can include applying a mask to a CMC structure, and subjecting the structure having an applied mask to a process for repair. In one embodiment, the applying a mask to a CMC structure can include applying a mask to a feature of a CMC structure.

Abstract: Ceramic matrix composite articles include, for example, a plurality of unidirectional arrays of fiber tows in a matrix having a monomodal pore size distribution, and a fiber volume fraction between about 15 percent and about 35 percent. The articles may be formed by, for example, providing a shaped preform comprising a prepreg tape layup of unidirectional arrays of fiber tows, a matrix precursor, and a pore former, curing the shaped preform to pyrolyze the matrix precursor and burnout the pore former so that the shaped preform comprises the unidirectional arrays of fiber tows and a porous matrix having a monomodal pore size distribution, and subjecting the cured shaped preform to chemical vapor infiltration to densify the porous matrix so that the ceramic matrix composite article has a fiber volume fraction between about 15 percent and about 35 percent.

Abstract: Provided is a method including obtaining ceramic matrix composite (CMC) with a first matrix portion including a silicon carbide and silicon phase dispersed therewithin, disposing a coating thereupon to form a sealed part, and forming thereupon another segment comprising a CMC, which may be another matrix portion including a silicon carbide and a silicon phase dispersed within therewithin. Also provided is a gas turbine component with a CMC segment including a matrix portion including a silicon carbide and a silicon phase dispersed therewithin, a sealing layer including silicon carbide enclosing the first segment, and a second segment on the sealing layer, wherein the second segment includes a melt-infiltrated CMC having a matrix portion including a silicon carbide and a silicon phase dispersed therewithin.

Abstract: Ceramic matrix composite articles include, for example, a plurality of unidirectional arrays of fiber tows in a matrix having a monomodal pore size distribution, and a fiber volume fraction between about 15 percent and about 35 percent. The articles may be formed by, for example, providing a shaped preform comprising a prepreg tape layup of unidirectional arrays of fiber tows, a matrix precursor, and a pore former, curing the shaped preform to pyrolyze the matrix precursor and burnout the pore former so that the shaped preform comprises the unidirectional arrays of fiber tows and a porous matrix having a monomodal pore size distribution, and subjecting the cured shaped preform to chemical vapor infiltration to densify the porous matrix so that the ceramic matrix composite article has a fiber volume fraction between about 15 percent and about 35 percent.

Abstract: Ceramic matrix composite articles include, for example, a plurality of unidirectional arrays of fiber tows in a matrix having a monomodal pore size distribution, and a fiber volume fraction between about 15 percent and about 35 percent. The articles may be formed by, for example, providing a shaped preform comprising a prepreg tape layup of unidirectional arrays of fiber tows, a matrix precursor, and a pore former, curing the shaped preform to pyrolyze the matrix precursor and burnout the pore former so that the shaped preform comprises the unidirectional arrays of fiber tows and a porous matrix having a monomodal pore size distribution, and subjecting the cured shaped preform to chemical vapor infiltration to densify the porous matrix so that the ceramic matrix composite article has a fiber volume fraction between about 15 percent and about 35 percent.

Abstract: A method can include applying a mask to a CMC structure, and subjecting the structure having an applied mask to a process for repair. In one embodiment, the applying a mask to a CMC structure can include applying a mask to a feature of a CMC structure.

Abstract: A pliable tape is generally provided that includes: a plurality of fibers forming unidirectional arrays of tows encased within a matrix material, with four adjacent fibers in the tape define an interstitial spacing therebetween. The matrix material comprises filler particles dispersed between adjacent fibers in the tape. In one embodiment, the filler particles have a median particle size defining the interstitial spacing such that the interstitial spacing is about 0.75 to about 1.1 of the median particle size. In another embodiment, the filler particles have a median particle size that is related to the surface-to-surface spacing between adjacent fibers, with the ratio of the surface-to-surface spacing between adjacent fibers and the median particle size being about 0.3:1 to about 1:1. Methods are also provided for forming a ceramic matrix composite.

Abstract: A pre-impregnated composite tape is provided that includes: a matrix material; a plurality of fibers forming unidirectional arrays of tows encased within the matrix material; and a plurality of filler particles dispersed between adjacent fibers in the tape. The fibers have a mean fiber diameter of about 5 microns and about 40 microns, and are included within the tape at a volume fraction of about 15% and about 40%. The plurality of filler particles have a log-normal volumetric median particle size, such that the tape has a ratio of the log-normal volumetric median particle size to the mean fiber diameter that is about 0.05:1 to about 1:1. A method is also provided for forming a ceramic matrix composite.

Abstract: According to a method set forth herein a plurality of preform plies having first and second preform plies can be associated together to define a preform. The preform can be subject to chemical vapor infiltration (CVI) processing to define a ceramic matrix composite (CMC) structure.

Abstract: A method for repair of composite materials includes applying a formulation to a ceramic matrix composite substrate. The formulation comprises a liquid carrier, a ceramic filler dispersed within the carrier, and a polymeric binder disposed in the carrier. The method further includes removing the carrier from the formulation to form a green composition; pyrolyzing the green composition to form a porous composition; disposing a liquid metal or metalloid within the pores of the porous composition to form an intermediate composite composition; and converting the liquid metal or metalloid to solid state to form a solid composite composition.

Abstract: A preform can be subject to chemical vapor infiltration (CVI) to define a ceramic matrix composite (CMC) structure, a supplemental preform can be added to the CMC structure to define an expanded structure and CVI can be performed using the expanded structure. The adding of a supplemental preform and performing CVI using the expanded structure can be repeated.

Abstract: A method for repair of composite materials includes applying a formulation to a ceramic matrix composite substrate. The formulation comprises a liquid carrier, a ceramic filler dispersed within the carrier, and a polymeric binder disposed in the carrier. The method further includes removing the carrier from the formulation to form a green composition; pyrolyzing the green composition to form a porous composition; disposing a liquid metal or metalloid within the pores of the porous composition to form an intermediate composite composition; and converting the liquid metal or metalloid to solid state to form a solid composite composition.