The chemical nature of the transfer film (TF) or third body layer (TBL) formed at the friction interface during automotive friction braking has been studied in detail using energy-dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analytical techniques. Optical and scanning electron optical methods have been used to examine the friction surfaces of the two elements of the friction couple, gray cast iron and asbestos free friction materials. The friction characteristics of asbestos free composites rubbing against grey cast iron were influenced to a great extent by the composition of the transferred layer. Friction performance was found to be independent of transfer film thickness and transfer film topography. Friction material wear rates and friction coefficient were not interrelated, i.e. high friction coefficient did not necessarily produce a high friction material wear rate and vice versa. Abrasive additions to asbestos free friction materials may either stabilize or destroy the third body layer without significantly affecting the friction coefficient. Transfer film chemistry was dependent upon abrasive morphology and mechanical properties. The complementary techniques of X-ray photoelectron spectroscopy and imaging X-ray photoelectron spectroscopy exposed the limitations of total reliance of spectral data for identification purposes.
A fundamental tribochemical study of the third body layer formed during automotive friction braking
Eine grundlegende tribochemische Untersuchung über den Transferfilm, der sich in Reibungsbremsen von Automobilen bildet
1994
7 Seiten, 6 Bilder, 1 Tabelle, 13 Quellen
Aufsatz (Zeitschrift)
Englisch
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