Advanced Ceramic-Metallic Composites for Lightweight Braking Systems.

摘要

According to the Federal Transit Administration Strategic Research Plan: Researching technologies to reduce vehicle weight can also lead to important reductions in fuel consumption and emissions. The power required to accelerate a bus and overcome rolling resistance is directly proportional to vehicle weight. Composite materials are one example of an FTA research area aimed at reducing vehicle weights. One way to reduce vehicle weight is through the development of lightweight components for advanced braking systems. Gray cast iron has been the material of choice in braking systems (such as in brake rotors and drums) because it is inexpensive and a large supply chain infrastructure is in place for engineering and manufacturing gray cast iron components. However, gray cast iron is a relatively heavy material. Utilizing lighter weight materials in braking systems would not only achieve better fuel economy by reducing the vehicles static weight but, since brake rotors and drums are rotating components, there would be a large multiplying effect on reducing the amount of energy required to increase their rotational speed as the vehicle accelerates. Finally, as the braking system is an unsprung weight, a lighter system would significantly improve vehicle handling performance and safety. In spite of obvious benefits to lightweight materials, there are significant technical and commercial challenges to overcome. Most lightweight materials do not have the physical, thermal, and tribological performance characteristics required for brake applications, such as a high strength and high thermal conductivity at elevated temperatures. Lightweight alternatives to cast iron that currently do exist are prohibitively expensive for general use in most vehicles.