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.
Selected Activities of Prof. Kostic's Nanofluid Research Group (more at www.kostic.niu.edu/DRnanofluids):
► Kostic, M and Simham, K.C., Computerized, Transient Hot-Wire Thermal Conductivity Apparatus for Nanofluids-Best HMT09 Conference Paper, Proceedings of the 6th WSEAS International Conference on HEAT and MASS TRANSFER (HMT'09), Ningbo, China, January 10-12, 2009. In RECENT ADVANCES in HEAT and MASS TRANSFER (Editor: Lifeng Xi), ISBN: 978-960-474-039-0; ISSN: 1790-5095, p. 71-78, WSEAS Press. 2009. (Also, Plenary Lecture: Heat Transfer, Thermal Energy and Entropy - Demystified )
A new and improved HWTC apparatus for thermal conductivity measurements of (nano)fluids has been recently developed. It employs innovative solutions for easy calibration of uniform Platinum wire tension and thus minimizing the strain influence on temperature measurement (i.e., minimizing the well-known and unwanted “strain-gage effect” on Pt-wire electrical resistivity); measurement of Pt-wire voltage drop independently from power wiring (four wires); and an effective off-centered mechanical design to minimize the fluid sample size (about 30 mL), but at the same time providing additional space for wiring (including three inside thermocouples for fluid temperature uniformity verification). Data acquisition hardware and software are optimized to minimize signal noise and enhance gethering and processing of useful data.
► Prof. Kostic has been awarded a NSF research grant (CBET-0741078 Thermal Transport & Thermal Processing) for "Exploring New Hybrid Polymer-Nanofluids with Enhanced Flow and Heat Transfer Characteristics," in 2007/2008.
►
Kostic, M., M. Golubovic, J.R. Hull and S.U.S.
Choi,
ONE-STEP METHOD FOR THE PRODUCTION OF
NANOFLUIDS, ANL invention S-105,821.
US Patent Number:
US 7,718,033 B1,
(PDF),
Publication Date 18 May 2010.
►
Kostic, M., M. Golubovic, J.R. Hull and S.U.S.
Choi,
One-Step Method
for the Production of Nanofluids, ANL invention
S-122,261,
U.S. Patent-Divisional Application No.12/729,494
filed by U.S. Department of Energy
(Brian John Lally/Katherine Baldwin, Patent Attorney) on
3/23/2010.
Additional Claims to the above.
► Kostic, M., “Critical Issues and Application Potentials in Nanofluids Research,” ASME-MN2006 Multifunctional Nanocomposites 2006 International Conference, September 20-22, 2006, Honolulu, Hawaii, ASME Proceedings, New York, 2006. (PPT & Photos or Seminar)
► Kostic, M., Effective Thermal Conductivity Errors by Assuming Unidirectional Temperature and Heat Flux Distribution Within Heterogeneous Mixtures (Nanofluids), (*) HMT'08-The5th WSEAS International Conference on HEAT and MASS TRANSFER, ID: 573-354, Acapulco, Mexico, January 25-27, 2008. Abstract: It is common practice to approximate temperature distribution and heat flux as unidirectional for heterogeneous mixtures if exposed to “over-all unidirectional” boundary conditions. This approach has been used to model and to arrive at the effective (or over-all average) thermal conductivity of heterogeneous mixtures (nanofluids). It is shown here, however, that due to the heterogeneity of system structure and properties the temperature distribution and heat flow will not be unidirectional (one-dimensional) and the errors due to such unrealistic (physically impossible) approximation may be much higher than anticipated.
►Nanofluid
Flow-and-Heat-Transfer Apparatus *
►NIU-MK Nanofluids Activities and Future Plans
