Wear debris from brake system materials: A multi-analytical characterization approach

In commercial automotive braking systems, consisting of a friction pad dry sliding against a pearlitic cast iron disc, the wear of the disc contributes significantly to the overall wear. In the present work, pin-on-disc sliding tests were carried out for determining the role of conventional heat-treatment conducted on cast iron discs on the friction and wear behavior of the above coupling. Wear rates of both disc and friction materials were reduced by almost one order of magnitude when the disc is preliminarily heat-treated and then ground to remove the surface decarburized layer that forms during the thermal cycle. Heat-treatment and heat-treatment plus grinding resulted also in the decrease of the friction coefficient, which was comparatively lower for the ground samples. The friction and wear behavior along with the contact temperature evolutions were rationalized according to the actual materials characteristics, as resulting from the different treatments.