Mössbauer spectroscopy characterization of automotive brake disc and polymer matrix composite (PMC) pad surfaces

In the last few years tribology researchers have attempted to characterize the braking film (third body) formed dynamically between disc and pad during frictional load. In automotive braking systems this friction layer is formed by the wear of two complex matrices and several analytical techniques are necessary for a comprehensive characterization. In this work Mössbauer Spectroscopy (MS) in transmission and backscattering modes, and X-ray Diffraction (XRD) were used to investigate the contact surfaces of polymer matrix composite (PMC) pads and cast iron discs, after they were tested in an Inertia Dynamometer Test Procedure (SAE J2784). Iron containing phases on the surfaces of disc and pad were identified, revealing the formation of magnetite and significant amounts of pyrite.