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A semi-empirical model predicting the final rotor surface temperature under thermal steady state as a function material properties (thermal conductivity, specific heat, density), rotor thickness and test parameters (inertial load, cooling air speed) was constructed. The key observation that led to the construction of this model was that the initial rotor surface temperature during a stop varied linearly with the net temperature rise of the rotor surface during that stop of a fade sequence. The final rotor temperature under thermal steady state, Tfss (also referred to as maximum steady state temperature or MSST), is given by: Excellent agreement between the predicted and observed values Tfss of was found. This model was used to predict performance changes as a result of material modifications and can serve as an excellent tool for rotor material optimization.

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.

Automotive brake rotors produced from metal matrix composites (MMCs) were subjected to dynamometer tests. The thermal response during fade stops, the failure temperature, and the wear performance of the rotors were studied as functions of various material and design parameters, such as rotor thickness, composition of the rotors, inertial load, and cooling air speed. The performance of the MMC rotors was also compared with that of commercially available production cast iron rotors. The data related to the maximum operating temperature (MOT) as a function of the silicon carbide level in a composite rotor is also presented. The testing indicates that metal matrix composite materials may be strong candidates for brake rotors in future models of motor vehicles.