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 or the preforms may be constrained during carbonization , typically by means for applying pressure . 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 .