Manufacture of functionally graded carbon-carbon composites

摘要

Annular brake disc preform (15), wherein 40 to 80 layers of reinforcement fibers of at least two different lengths (11, 19) ranging from 10–60 mm are distributed in a planar gradient throughout the body of the preform, with the reinforcement fibers located near the exterior planes of the disc being predominately shorter fibers (11) and with the reinforcement fibers located in the central planes of the disc being predominately longer fibers (19). Also, process of making carbon-carbon composite preforms by: providing chopped pitch or PAN fibers (11, 19) of at least two different lengths; directing a robotic spraying apparatus to spray the chopped fibers into an annular mold (5) in 40 to 80 concentric iterations of chopped fiber deposition to provide a matrix of fibers in the mold; depositing a curable binder into the mold to intermix the binder with the fiber matrix; compressing the fiber matrix and curable binder within the mold; curing the binder to form a preform matrix; filling the preform matrix with pitch to form a pitch matrix; and subjecting the pitch matrix to chemical vapor deposition to form a carbon-carbon composite preform (15).