Carbon fiber based ceramic brake materials - concepts and applications

Carbon fiber reinforced ceramics manufactured via liquid silicon infiltration (LSI) have been developed at DLR since the late 1980s. Carbon fibers are infiltrated with a polymer based matrix which will be converted to carbon during the pyrolysis process and then reacted to SiC by LSI. The resulting C/C-SiC composites show high abrasion resistance, sufficient heat capacity and high corrosion stability. These properties make the composites attractive for passenger car brake systems. Today, brake discs are manufactured in serial production very efficiently, being reinforced with short fibers and coated with a frictional SiC rich layer on the surface. Apart from this application, also other frictional applications have been realized, as e.g. brake pads for high velocity elevators or brake discs for the Airbus A400M propeller brake system. A detailed overview of various C/C-SiC friction materials, and the necessary microstructural design adapted to the individual frictional application will be presented. Additionally, new concepts for brake materials, focusing on enhanced preform technologies, like knitting or stitching, combined with short fiber reinforced frictional layers, will be shown and their potential will be discussed.