Nanomanipulation, nanotribology and nanomechanics of Au nanorods in dry and liquid environments using an AFM and depth sensing nanoindenter.

Nano-objects in dry and liquid conditions have shown reductions in friction and wear on the macroscale. In this research, for the first time, Au nanorods were studied on the nanoscale under dry conditions and submerged in water for their effect on friction and wear reduction. The data were compared with spherical Au nanoparticles. Atomic force microscopy (AFM) experiments on the nanoscale were performed in single-nano-object contact with an AFM tip, where nano-objects were laterally manipulated, and multiple-nano-object contact with a tip attached to a glass sphere sliding over several nano-objects. Nanoscale and macroscale wear tests with an AFM and ball-on-flat tribometer were performed to relate friction and wear reduction on both scales. Results indicate that Au nano-objects contribute to friction and wear reduction due to the reduced contact area and possible rolling and sliding on the nanoscale. Compression tests (global deformation) using a nanoindenter with a flat punch were used to investigate the mechanical behavior under load and its relation to friction and wear reduction. Repeat compression tests of nano-objects were performed which showed a strain hardening effect and increased pop-ins during subsequent loads.