Metal-matrix friction materials made by powder metallurgy technologies are used in severe duty applications, which require the friction material to perform at high sliding speeds, high pressures, and at bulk temperatures in excess of 500°C in air. For heavy off-highway vehicles used in construction and mining, secondary brake systems are required that must perform both parking brake and emergency brake functions. Given the weights of the vehicles involved, and the desire to keep such systems of modest size and cost, the static and high energy dynamic performance of the brake materials must be quite high. Iron is sometimes used as the predominant metal in the matrix, due to cost, environmental concerns, and high energy capability. This investigation compares the wear, the static and dynamic friction levels, and the temperature capabilities of several iron-based sintered metallic brake materials, whereby the formulations were determined by a DOE. Some variations of the optimum formulation with varying alloying schemes of the iron matrix were also tested. For comparison, test data from a Cu-based and a low-met formulation are also presented. Scaled dynamometer tests on automotive-sized brake systems were conducted in addition to mechanical property and microstructure evaluations.
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