Patent ID: 8454867

Claim:
A method for the manufacture of pitch-densified carbon-carbon composite brake discs from carbon fiber preforms, the method comprising the following sequential steps: (a) heat treating a carbon-carbon composite preform in the shape of a brake disc at 1600-2540° C.; (b) directly following heat treating step (a), subjecting the heat-treated preform to Chemical Vapor Deposition/Chemical Vapor Infiltration processing to produce a carbonized fiber preform which: (i.) has a rough laminar microstructure and is densified to a density of about 1.4 grams per cubic centimeter; or (ii.) has a smooth laminar microstructure and is densified to a density of about 1.2 grams per cubic centimeter; or (iii.) has an isotropic microstructure and is densified to a density of about 1.1 grams per cubic centimeter; (c) infiltrating the preform with an isotropic low to medium char-yield pitch derived from coal tar, employing Vacuum Pitch Infiltration processing or Resin Transfer Molding Processing; (d) carbonizing the pitch-infiltrated preform at 900-2400° C., wherein pressure and a can are used to prevent and contain any pitch exudation during heat treatment; (e) machining the surfaces of the resulting carbonized preform; and (f) repeating steps (c) through (e) at least two additional times to raise the density of the carbon-carbon composite preform to at least approximately 1.75 g/cc; wherein the carbon-carbon composite brake disc preform is densified with an isotropic coal tar pitch to a density of approximately 1.3-1.6 grams per cubic centimeter in the first implementation of step (c); and wherein the carbon-carbon composite brake disc is densified with coal tar pitch to a density of at least approximately 1.75 grams per cubic centimeter in the third implementation of step (c).