Water suspended nanosized particles released from nonairborne brake wear debris

The paper addresses characterization of nanosized particles which may be potentially mobilized from nonairborne brake wear debris when being suspended in the water environment. Wear particles were generated in a fullscale automotive brake dynamometer simulation using a model low metallic friction composite and a gray cast iron disc. The three types of samples were analyzed: (a) nontreated wear debris, (b) wear debris particles dissolved in water and (c) filtered suspension of dissolved wear debris particles. Samples were subjected to a combination of analyses (XRD, TEM, SEM with EDS, Raman microspectroscopy and vibration magnetometry). Raman microspectroscopy revealed the presence of Fe2O3, Fe3O4, BaSO4, CaCO3, MoS2, graphite and amorphous carbon in the wear debris samples. The TEM analysis of particles in water suspension proved that the nanosized particles are released into water. Barite particles were detected in the water suspension by Raman microanalysis most often. The prepared filtered suspension exhibited magnetic character which is probably related to the presence of magnetic forms of iron and iron oxides.