Worn Surface Characteristics of a Friction Material during Braking Simulation Test

In this study, the chemical and microstructural changes occurring during braking simulation tests at the surface of a commercial brake lining material were investigated by scanning electron microscopy equipped with an energy-dispersive X-ray spectrometer (X-EDS). It could be shown that patches of a third body material develop, comprising a compositional mix of all constituents of the pad and iron oxides from the disk. The majorities of particles rich in carbon which appeared dark grey remained totally or partially uncovered and did not form preferential supports of secondary plate development. It was observed that filler mineral powders, such as barite (BaSO

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) and calcium carbonate, which are friable particles, easily wear and generate an important part of third body rich in C, Ca, Ba and Fe elements. Rockwool fibres and shots contributed to the formation of the bearing surface by forming primary support of development of flat plates. The major wear mechanism was delamination of filler particles from the organic binder, supported by local degradation of the phenolic resin during asperity heating.