Development of Hybrid, Tribological Nanofluids with Enhanced Lubrication and Surface-Wear Properties

  M. Kostic

  Department of Mechanical Engineering, Northern Illinois University

  www.kostic.niu.edu/DRnanofluids

Summary: A novel idea that will be explored in this project is to combine drag-reducing, polymer additives with nanoparticles, and thus develop new drag-reducing lubrication nanofluids, namely, stable suspensions of carbon and metal based nano-scale particles in common lubrication fluids. The goal is to develop and optimize hybrid nanofluids with enhanced lubrication and surface-wear properties. The ultimate goal of the project will be to understand the underlying surface-chemistry and physical phenomena of diffusion, flow and heat transfer in these novel nanofluids, by correlating and modeling measured micro/nano- and macro-characteristics, thus making possible development and manufacturing optimization of tailor-made, functional-nanofluids with significantly enhanced lubrication properties, critical for existing and emerging applications.  

The application of nanoparticles in tribology has received attention in recent years. Some results indicate that the tribological performance of lubricating oils can be improved significantly by dispersing carbon and metallic-based nanoparticles in those lubricants. Substantial increase in maximum non-seizure load and reduction in wear has been observed, along with reduction of friction coefficient by over 25 percent using Ni-based nanoparticles in lubricants. The tribological mechanism may be contributed by enhanced adhesion-film in the contact regions, which prevented the direct contact of rubbing surfaces and greatly reduced the frictional force between the sliding surfaces. Another possible mechanism may be that nanoparticles roll within the lubricants, thus transforming sliding- into more efficient rolling-friction at the micro/nanoscale.

A graduate student will be working on a project to develop tribological POLYnanofluids by mixing different concentrations of different polymer additives and different nanoparticles in different base fluids, using different preparation methods (to be developed and optimized):

·   Additional additives may and should be used to facilitate development of tribological POLYnanofluids, like surfactant, pH enhancers (or neutralizers), or similar.

·   Different mixing methods under different process parameters should be used and/or developed to facilitate and enhance optimal structural development of tribological POLYnanofluids, with desired tribological properties, and flow and heat-transfer characteristics.

·   Viscosity of base fluids, nanofluids (base fluids with nanoparticles), polymer-solutions (base fluids with polymer additives), and POLYnanofluids (base fluids with polymer additives and nanoparticles), will be measured at NIU with existing digital viscometer. More advanced viscometer/rheometer may be purchased if funds become available.

This project will be extension of existing NIU collaboration related to nanofluids production and characterization in Argonne National Laboratory (ANL). The existing one-step method developed in Argonne National Laboratory (ANL), although an excellent concept, has critical shortcomings, and only very limited quantities of nanofluids have been produced so far. One objective will be to resolve critical challenges in the nanofluid manufacturing process, by improving the ANL one-step nanofluid production method (this investigator’s collaborative invention and patent application with ANL are pending). Subsequently, macroscopic viscosity with tribological and flow characterization of the polymer-nanofluids will be undertaken. These macro-scale measurements may be extended, by collaboration with NIU Physics and ANL, with nano-scale measurements of structure and dynamics using small angle x-ray and neutron scattering, x-ray photon correlation spectroscopy (XPCS) and laser light scattering. The results of these studies may be used to optimize fluid tribological properties.

This research may open the road for development of diverse, complex nanofluids with polymer additives, dubbed POLY-nanofluids, with unprecedented application potential.  By studying (and understanding) nanofluids in the lab and nature, using new and available experimental techniques, and by developing computer based models of these fluids and related phenomena, new methods and tools for custom-design of nanofluids with enhanced properties may be developed.