Low cost, high density c-c composites densified by cvd/cvi for aircraft friction materials

Abstract

Carbon-carbon composites made by needling together woven or nonwoven fabric made from carbon-containing fibers followed by carbonizing the fabric preforms are described. The carbon fiber preforms can be needled either in a carbonized or in an uncarbonized state. The uncarbonized fiber preforms would go through a carbonization/heat-treat step following the needling process. Final preform thickness and fiber volume is also controlled at carbonization, for instance by varying the level of pressure applied to the preforms during carbonization. For example, the preforms may be unconstrained during carbonization (i.e., no pressure is applied to them) or the preforms may be constrained during carbonization, typically by means for applying pressure (e.g., weight placed on top of the preforms). The preforms are then infiltrated via CVD/CVI processing in order to increase their density, resulting in a carbon-carbon composite which is suitable for use as, for instance, a brake disc or pad in aircraft and automotive brake systems.