Tribological characteristics of nanocrystalline copper

In the present study, two sets of powder metallurgy copper samples, with gain sizes of 99 nm and 63 nm, respectively, were investigated under different tribological conditions. The wear behavior of these materials was studied through a pin-on-disc configuration using sliding velocities of 0.5, 1 and 2 m/s with normal loads of 10 and 30 N. The finer-grained copper was able to outperform (by between 4- to 16-fold) its coarser-grained counterpart under severe test conditions, but no advantage was observed when conditions were milder. Scanning electron microscopy revealed the dominant wear mechanisms to be oxidative wear under mild sliding, with a transition to adhesive wear with increases in sliding speed and normal load.