Some insights into effects of nanoparticles on sliding wear performance of epoxy nanocomposites

In this work, the effects of nanoparticles on the tribological performances of epoxy-based composites were systematically investigated on a ball-on-plate apparatus in dry sliding conditions with a hardened steel ball. A series of nanosilica/epoxy nanocomposites were fabricated, using nanoparticles prepared by a special sol–gel technique, well dispersed up to 20 wt%. The wear results showed that nanosilica particles could improve the wear resistance of epoxy nanocomposites only when the content of nanoparticles was higher than a critical value (10 wt%), even though the static mechanical properties of the nanocomposites (such as microhardness, modulus, fracture toughness) were almost proportionally improved with an increase in the content of nanosilica particles. It was found that the continuous transfer film on the steel ball could be formed only with relatively high nanoparticle contents, ≥10 wt%, which may play a key role in determining the wear performance of nanocomposites in steady wear stage. On the basis of microscopic observations, the wear mechanisms for epoxy nanocomposites were further discussed.