This Small Business Innovation Research Phase I project involves development of a new class of lightweight aluminum superalloys to replace much heavier cast iron in automobile brake rotors. There is a large market for brake rotors, estimated worldwide at $10 billion. Replacing four cast iron brake rotors in a typical sedan will reduce its weight by about 80 pounds, which translates into significant improvements in gas mileage and reductions in tailpipe emissions. These advantages are anticipated to be compelling to automakers, because of the new U.S. Corporate Average Fuel Economy (CAFE) rules. If successful, the new aluminum superalloys can capture a 2.5% share of the brake-rotor market, equivalent to 25 million brake rotors per year, during the replacement cycle. Other benefits of the switch to aluminum alloy brake rotors include: (a) rapid heat dissipation from the brake surface; (b) faster stopping and acceleration, and better automobile handling; (c) much higher corrosion resistance due to the usage of aluminum; and (d) the elimination of corrosion products (rust which forms on cast iron rotors leads to inhomogeneous heat distribution during braking).
Current commercial lightweight age-hardenable aluminum alloys are not useable above 220 degrees C because the strengthening precipitates dissolve. Thus, there is no widespread commercial usage of aluminum alloys for applications that involve elevated temperatures; e.g., automotive brake rotors. A first alternative is aluminum alloys containing 0.15-0.30% by weight of scandium (which contains heat- and coarsening-resistant Al3Sc precipitates). Another alternative is aluminum-matrix composites with ceramic particles or fibers. The former contain, however, an expensive element (scandium is comparable to gold in price) and the latter involve complicated and expensive processing routes, respectively, severely limiting their usage. The goal of Phase I is to develop successfully and patent new proprietary alloy compositions and heat treatment procedures to produce Sc-free aluminum superalloys able to sustain months of exposure at 400 degrees C and above, without a significant loss of strength. We will also manufacture a prototype brake rotor, in order to further prove out this material.
