Influence of intergranular metallic nanoparticles on the fretting wear mechanisms of Fe-Cr-Al2O3 nanocomposites rubbing on Ti-6Al-4V

This paper presents a study concerning the influence of the amount of metallic nanoparticles on the wear behaviour of Fe0.5-Cr0.5-alumina nanocomposites rubbing on Ti-6Al-4V in fretting. Due to the elaboration process (metal-oxide nanopowder prepared by selective reduction in hydrogen of oxide solid solution and densified by spark plasma sintering), these materials generally own two sorts of nanoparticles: the intragranulars (size: <10nm) located within the alumina grains and the intergranulars (size: >100nm) located at the grain boundaries. This paper focuses on the role of each sort of nanoparticles with respect to the wear of the nanocomposite. Results show that the presence of intergranular nanoparticles is crucial for improving the wear resistance of nanocomposites whereas the intragranulars rather improve the mechanical properties of matrix grains. The lowest wear rate of the nanocomposite is obtained when the amount of intergranulars is about 3.5 wt%. Finally, the fretting wear mechanism of nanocomposites and the mechanism enabling to prevent it by using nanoparticles are both identified and discussed.