High energy braking behaviors and tribo-map constructions of Cu metal matrix composites with different Cr volume contents

Cr, a promising abrasion component, has been introduced into Cu metal matrix composites (Cu-MMCs) to improve their high-energy braking performance. The Cu–Cr interfacial characteristics, worn surface/subsurface morphologies, and effect of Cr on the high energy braking behaviors of Cu-MMCs were measured in this study. The results indicate that an increase in Cr content prevented severe surface plastic deformation (0–5 vol. % Cr) and promoted the formation of mechanical mixed layer (MML) (15–20 vol % Cr), facilitated the improvement of wear resistance and the coefficient of friction, and reduced the thermal fade of composites. The main wear mechanism of the Cu-MMCs changed from adhesion (0–10 vol % Cr) or abrasion (10–20 vol % Cr) to delamination or mechanical mixing with an increase in braking energy density (BED). A series of corresponding friction, wear, and wear mechanism maps were established, which revealed the variation in the wear mechanism with the Cr content and BED.