Patent ID: 8778249

Claim:
A process for producing a porous, carbon-containing preform being used in a brake disk, comprising: superposing sheets of a first unidirectional carbon fiber fabric on top of one another; needle-punching the superposed sheets of the first unidirectional carbon fiber fabric to form a body having a density of 0.8 to 1.0 g/cm 3 ; alternately superposing a sheet of a second unidirectional carbon fiber fabric and a sheet of a first randomly-arranged-carbon-fiber fabric on top of the body; needle-punching the alternately-superposed sheets of the second unidirectional carbon fiber fabric and the first randomly-arranged-carbon-fiber fabric, and the body together to form an intermediate layer on top of the body, the intermediate layer having a density of greater than 0.5to less than 0.8 g/cm 3 ; superposing sheets of a second randomly-arranged-carbon-fiber fabric on top of the intermediate layer; needle-punching the superposed sheets of the second randomly-arranged-carbon-fiber fabric, the intermediate layer and the body together to form a frictional layer on top of the intermediate layer, the friction layer having a density of 0.01 to 0.5 g/cm 3 .