Abstract: Constraint fixture for processing annular preforms. The constraint fixture is made up of a lower plate, a top plate, a ring for the outside diameter of an annular preform being treated within the constraint fixture, and a ring for the inside diameter of the annular preform. The outside diameter and inside diameter rings are made of thin flexible sheet metal strips or thin flexible carbon-carbon composite strip material. The thin flexible strips are joined together by deformable joints, so that the flexible constraint system retains pitch within the fibrous matrix of the preform. The outside diameter strips may be joined together by expandable joints and the inside diameter strips may be joined together by collapsible joints. Also, a method of avoiding damage to an annular fibrous preform, e.g., an aircraft brake disc preform, during a carbonization procedure. This method involves carbonizing the annular fibrous preform in the constraint fixture of the invention.

Abstract: Method of carbonizing pitch-infiltrated fibrous annular preform by: infiltrating the preform with pitch; placing the pitch-infiltrated preform in a constraint fixture having an ejector base plate, an inner wall, an outer wall, and a top press plate; selecting the relative sizes of the preform and the constraint fixture so that a layer of inert friable material may be situated between the preform and walls of the constraint fixture; placing inert friable material (e.g., activated carbon) between the preform and the top, bottom, and walls of the constraint fixture; and subjecting the pitch-infiltrated fibrous preform to carbonization in the constraint fixture. The activated carbon or other inert friable material adsorbs pitch molecules that escape the preform during carbonization, which reduces problems with foaming.

Abstract: Method of manufacturing dense carbon-carbon composite material by: infiltrating a fibrous preform with pitch to form pitch-infiltrated preform; carbonizing the pitch-infiltrated preform; injecting resin or pitch into the preform in a mold; oxygen stabilizing the filled preform and carbonizing and heat-treating the oxygen-stabilized impregnated preform; and subjecting the preform to a single final cycle of chemical vapor deposition. This process reduces densification time as compared to comparable conventional carbon-carbon composite manufacturing procedures.

Abstract: Method for manufacturing a carbonized carbon-carbon composite preform, by: mixing (a) chopped carbon fiber, chopped stabilized pitch fiber, or chopped oxidized polyacrylonitrile (PAN) fiber, (b) thermoplastic pitch binder powder, and (c) activated carbon powder to form a mixture of 15-60 parts by weight of chopped carbon fiber or chopped stabilized pitch fiber or chopped oxidized PAN, 28-83 parts by weight of thermoplastic pitch binder powder, and 1-12 parts by weight of activated carbon powder; depositing this mixture into a mold; pressing/heating the materials in the mold to form a preform by compaction; removing the compacted preform from the mold; and carbonizing the compacted preform. The preform is preferably configured in the form of an aircraft landing system brake disc.

Abstract: A restraint fixture (12) is disclosed that includes a preform retention region configured to limit contracting forces applied against a preform (10) in the preform retention region when the restraint fixture (12) thermally contracts. In one embodiment, the restraint fixture (12) comprises a band (12) having a first surface defining the preform retention region and a first expansion portion (26, 28, 29) adapted to deform upon application of a force to the band (12).

Abstract: Molding apparatus for rapid transfer of molten resin or pitch in an infiltration molding process. The apparatus includes e.g. an extruder (4) for melting and conveying a resin or pitch and a mold (10) arranged so that resin or pitch is conveyed to a mold insert cavity (19) within the mold. The mold insert contains an internal protrusion such as a locating ring (25) for positioning a porous body (1, 18) within the mold insert cavity in a position that brings about unidirectional flow of the molten resin or pitch through the porous body. Also, rapid resin or pitch infiltration molding process that includes injecting a high melting point, high viscosity, molten resin or pitch into the mold to effect a unidirectional impregnation of a heated preform via a pressure gradient in the mold.

Abstract: The present invention makes use of loose fibrous material (for instance, chopped fibers) as reinforcement matrix material in the manufacture of carbon-carbon composites. In accordance with this invention, a constraint fixture is provided which can be separated from the mold. The constraint fixture has an internal shape corresponding to the shape of a desired preform component, with the internal shape being defined by a bottom plate (2), an annular ejector plate (3, 3?), a inner wall (10), an outer wall (4), and an annular top plate (11, 11?). The constraint fixture is normally made of metal, porous ceramic, or carbon material. The constraint fixture of the mold holds the loose matrix materials (fibers, along with any fillers and/or additives). The mold assembly itself is segmented, so that the constraint, fixture and the loose fill materials in the fixture can be removed and subjected to further processing as a unit.