A method of preparing a ceramic fabric and ceramic matrix composite components constructed from the ceramic fabric include transforming ceramic tows, or ceramic fabrics, to varying degrees from a first tow geometry to a second tow geometry, thereby reducing a first dimension of the ceramic tows and increasing a second dimension of the ceramic tows orthogonal to the first dimension. Plies constructed with flattened tows, or as-received tows, have various inter-tow pore sizes that are arranged with increasing inter-tow pore size towards exterior surfaces of the preform structure.

A method of preparing a ceramic fabric for use in a ceramic matrix composite includes transforming a ceramic tow from a first tow geometry to a second tow geometry, thereby reducing a first dimension of the ceramic tow and increasing a second dimension of the ceramic tow orthogonal to the first dimension to produce a flattened tow. The method includes weaving or braiding the flattened ceramic tow to form a ceramic fabric.

A method of spreading fiber tows includes assembling a fibrous composite from a plurality of tows, applying an aqueous solution to the fibrous composite, freezing the fibrous composite after applying the aqueous solution, freeze drying the fibrous composite to remove water from the fibrous composite, and heating the fibrous composite after freeze drying to remove a cryoprotectant from the fibrous composite. The aqueous solution comprises water and the cryoprotectant and freezing the fibrous composite spreads filaments within the plurality of fiber tows.

A method of spreading fiber tows includes applying a coupling medium to a surface of a fibrous structure, positioning an ultrasonic probe adjacent to the surface of a fibrous structure, such that a tip of the ultrasonic probe is in contact with the coupling medium, moving at least one of the ultrasonic probe and the fabric structure relative to the other of the ultrasonic probe and the fibrous structure according to a first pattern, and imparting ultrasonic vibration with the ultrasonic probe to the surface of the fibrous structure while moving the ultrasonic probe along the surface of the fibrous structure. Imparting ultrasonic vibration to the surface of the fibrous structure spreads tows of the fibrous structure.

A method of spreading fiber tows includes applying a coupling medium to a surface of a fibrous structure, positioning an ultrasonic probe adjacent to the surface of a fibrous structure, such that a tip of the ultrasonic probe is in contact with the coupling medium, moving at least one of the ultrasonic probe and the fabric structure relative to the other of the ultrasonic probe and the fibrous structure according to a first pattern, and imparting ultrasonic vibration with the ultrasonic probe to the surface of the fibrous structure while moving the ultrasonic probe along the surface of the fibrous structure. Imparting ultrasonic vibration to the surface of the fibrous structure spreads tows of the fibrous structure.

A method and a device for opening a fiber bundle, capable of performing a fluctuating operation, at a high speed, of pushing a part of a conveyed fiber bundle by a contact member into a stress state and then separating the contact member from the fiber bundle so as to temporarily relax the fiber bundle, and also capable of reducing damage to the fiber bundle. The device for opening a fiber bundle includes a conveying portion 5 for pulling out a fiber bundle Tm from a yarn feeding body 11 and conveying it in a fiber length direction, a fiber-opening processing portion 3 for opening the fiber bundle by moving a fiber in a width direction while bending the fiber by letting a fluid pass through the conveyed fiber bundle Tm, and a fluctuation imparting portion 4 for rotating a contact member 42 in a direction inclined with respect to a conveyance direction while bringing it into contact with the conveyed fiber bundle Tm and pushing a part of the fiber bundle Tm into a stress state, and then separating the contact member 42 from the fiber bundle Tm in the stress state so as to temporarily bring the fiber bundle Tm into a relaxed state.

A method and a device for opening a fiber bundle, capable of performing a fluctuating operation, at a high speed, of pushing a part of a conveyed fiber bundle by a contact member into a stress state and then separating the contact member from the fiber bundle so as to temporarily relax the fiber bundle, and also capable of reducing damage to the fiber bundle. The device for opening a fiber bundle includes a conveying portion 5 for pulling out a fiber bundle Tm from a yarn feeding body 11 and conveying it in a fiber length direction, a fiber-opening processing portion 3 for opening the fiber bundle by moving a fiber in a width direction while bending the fiber by letting a fluid pass through the conveyed fiber bundle Tm, and a fluctuation imparting portion 4 for rotating a contact member 42 in a direction inclined with respect to a conveyance direction while bringing it into contact with the conveyed fiber bundle Tm and pushing a part of the fiber bundle Tm into a stress state, and then separating the contact member 42 from the fiber bundle Tm in the stress state so as to temporarily bring the fiber bundle Tm into a relaxed state.

A partially separated fiber bundle includes a separated fiber section and an unseparated fiber section, being configured to give a ratio A.sub.max/A.sub.min of 1.1 or larger and 3 or smaller, when the number of fiber bundles contained in the width direction of the partially separated fiber bundle (fiber separating number: N.sub.n) measured at a freely selected point P.sub.n (where, n represents an integer of 1 to 100, and freely selected points P.sub.n and P.sub.n+1, excluding n=100, being 50 cm or more away from each other), is divided by a full width of W.sub.n of the partially separated fiber bundle, to calculate the fiber separating number per unit width A.sub.n, and assuming its maximum value as A.sub.max and its minimum value as A.sub.min.

A partially separated fiber bundle includes a separated fiber section and an unseparated fiber section, being configured to give a ratio A.sub.max/A.sub.min of 1.1 or larger and 3 or smaller, when the number of fiber bundles contained in the width direction of the partially separated fiber bundle (fiber separating number: N.sub.n) measured at a freely selected point P.sub.n (where, n represents an integer of 1 to 100, and freely selected points P.sub.n and P.sub.n+1, excluding n=100, being 50 cm or more away from each other), is divided by a full width of W.sub.n of the partially separated fiber bundle, to calculate the fiber separating number per unit width A.sub.n, and assuming its maximum value as A.sub.max and its minimum value as A.sub.min.

A technique for stable, high-speed treatment of reinforcement fiber. In a state where a unidirectional fiber bundle is held between a supporting surface of a support and a pressing surface of a resonator ultrasonically vibrating in a pressing direction perpendicular to the supporting surface, a pressed part of the unidirectional fiber bundle pressed by the pressing surface is moved in a longitudinal direction of the unidirectional fiber bundle. By doing so, the unidirectional fiber bundle can be stably treated at high speed when the unidirectional fiber bundle is opened or impregnated with a resin.