Bharat Bhushan, Ohio State University
The investigation of the effects of tribocharging and scale on mechanical properties of nano-objects, such as nanotubes, nanobuds and nanohorns from compounds such as molybdenum disulfide, tungsten disulfide and carbon and their incorporation into petroleum-based lubricants, is proposed in this research. Incorporating these known solid lubricants into petroleum-based oils may lead to enhanced lubricity. However, as sliding progresses over time, an increase in attractive electrostatic forces could lead to greater adhesion. Moreover, nano-objects have shown increased hardness and elastic modulus as compared to the bulk. During sliding, nano-object aggregation may occur, leading to changes in morphology of the adhered nano-objects and thus change in the mechanical properties. The use of atomic force microscopy (AFM) and electrostatic force microscopy (EFM) provides the mechanism for the characterization of morphology and charge density.
Initially, nanotubes, nanobuds and nanohorns will be deposited on metal and ceramic substrates either as dry nano-objects or as dispersions in petroleum-based oils. In the next phase, tribocharging studies will be performed using AFM and EFM to correlate adhesion and electrostatic attraction. Lastly mechanical properties will be evaluated using the Hysitron nanoindenter. Ball-on-flat tribometer studies will be performed on the macroscale along with phase two and three tests. This research will lead to an enhanced understanding of the properties of inorganic nanotube, nanobuds and nanohorns, and will lead to the creation of next generation petroleum-based oils with enhanced properties.
1) Study of dry nano-objects
2) Study of nano-object and petroleum hybrid lubricants
Progress to date
Time was spent locating personnel with the necessary research background to perform the experiments outlined in the proposal. A new post-doc was recently hired and another researcher will be starting in fall, 2013. Significant progress is expected to be made in the coming year.