Development of Advanced Reinforced Aluminum Brake Rotors

Failure of reinforced-aluminum brake rotors under severe dynamometer test conditions has been characterized by the Maximum Operating Temperature, MOT, the temperature at which one of the rotor rubbing surfaces fails via scuffing. It is believed that this failure takes place when the frictional force exceeds the shear strength of the rotor material. Rotors produced from cast 360 alloy reinforced with 20 volume percent silicon carbide particulates [360/SiCp(20)] have been found to have MOTs of 449°C. The MOT can be raised by increasing the silicon carbide level in the reinforced aluminum, but is ultimately limited by lower melting points of the silicon containing alloys that must be used with this reinforcement to prevent aluminum carbide formation during processing.

Aluminum composite rotors using aluminum oxide as the reinforcement have been developed with significantly higher MOT (538°C) compared to the silicon carbide-reinforced aluminum rotors. This study describes the rationale, based on analysis of extensive dynamometer test data base, for developing such alumina-reinforced metal matrix composite rotors. A process for manufacturing these rotors has been demonstrated on a small scale and will be discussed in this paper. A manufacturing facility for alumina-reinforced rotors, scheduled to be operational in the second quarter of 1995, will also be described.