Effect of reinforcement type, size, and volume fraction on the tribological behavior of Fe matrix composites at high sliding speed conditions

摘要

In this paper we studied the tribological behavior of iron matrix composites at high sliding speeds (25-35 m/s) typical of aircraft braking conditions. We developed two types of Fe matrix composites with different elastic modulus reinforcements: silica (71 GPa) and mullite (143 GPa) particulates using powder metallurgy. Two different size ranges: large (150-250 μm) and small sizes (1-10 μm) and a range of volume fractions of the particulates were also considered. The dry sliding wear and braking performance of the composites were investigated using a sub-scale disc braking dynamometer. The wear tests of the composites show that large size and high volume fraction of reinforcement particles provides better wear resistance and braking performance at high sliding speed conditions (25 m/s-35 m/s) for both Fe/silica composites and Fe/mullite composites. Significantly, Fe/mullite composites at lower volume fractions showed greater wear resistance than the Fe/silica composites due to the higher elastic modulus of the mullite particles. A wear track examination of composites showed that different wear mechanisms were operative at the different speeds. Our results indicate that composites with a high volume fraction of large sized reinforcement particles of high elastic modulus are to be preferred for braking performance and low wear loss at high sliding speed applications.