Tribology

Laser Glazing of Railroad Rails Wheel/rail interactions account for a significant fraction of the energy consumed in rail transport. Past studies have indicated that energy savings could be as high as 24% when friction at the wheel/rail interface is properly managed. The key aspect is control of the friction forces. Our research focuses on the development of a laser glazing technique that imparts a durable, low-friction surface to the gage face of the rails to reduce parasitic frictional losses between the flange and rail gage. More...

The Tribology Section conducts research on advanced tribological systems (e.g., surface engineered materials, lubricants, fuels, and fuel/lubricant additives) for use in aggressive environments. A major portion of this activity focuses on the development and evaluation of high-performance coatings that can be applied to a wide range of materials. Also being investigated are how fuel and lubricant additives interact with surfaces under boundary-layer-lubrication regimes. The coatings are primarily intended to protect engine-component surfaces that undergo sliding and rolling contact in advanced transportation systems, including those powered by diesel and gasoline engines, as well as by advanced energy conversion systems being developed under the sponsorship of DOE’s Office of FreedomCAR and Vehicle Technologies (FCVT); Office of Hydrogen, Fuel Cells, and Infrastructure Technologies; and U.S. industry. The overall goal of the Tribology Section is to promote industrial competitiveness by developing new tribological technologies and by solving problems associated with friction, wear, and lubrication. The Section has established and maintained close contact with transportation-related industries to determine their critical tribological needs and to facilitate the transfer of technologies developed at ANL.

The Section provides technical oversight for approximately $11 million in FCVT programs. These programs include computational fluid dynamics of tractor-trailers, friction and wear of engine components and brake materials, and thermal management through use of nanofluids, evaporative cooling, and nucleated boiling. Technical oversight is also provided on major FCVT programs related to “the more electric truck,” lightweight auxiliary power units, ceramic rotors and disks for disk brakes in heavy vehicles, hybrid mining equipment, locomotives, and class 3-6 trucks.

The Section’s activities include the development of advanced surface modification and material processing technologies, and evaluation of tribological properties. In the area of coatings that reduce friction, the Section has ongoing projects with DOE on development of near-frictionless carbon (NFC) coatings, superhard nanocomposite coatings that show potential for applications where formulated lubricants are employed, and electroless wet-chemical coatings used to fabricate small diesel injector orifices. Related projects include development of processes to join advanced materials using superplastic deformation and advanced glasses for X�]ray imaging.

In the field of tribological evaluations, the Section has projects on laser glazing techniques to reduce parasitic friction losses between wheels and rails (railroad transportation), and laser engineered treatment of surfaces (microdimples) to improve friction behavior of surfaces during hydrodynamic lubrication regimes. Also being evaluated are parasitic energy losses in heavy-duty diesel engines to determine the impact of low friction surfaces and low-viscosity lubricants on fuel economy, durability of advanced materials (NFC, low-friction polymers, etc.) for air compressor applications in fuel cell systems, and erosion properties of materials exposed to nanofluids. Further, the Section has major projects to characterize coating properties and tribological mechanisms, including characterization of boundary layer lubrication mechanisms, and the structural, thermal, and electrical properties of advanced coatings (e.g., NFC).

Efforts are also in place to commercialize technologies developed in the Tribology Section. These include numerous efforts to deposit NFC coatings on prototype components for specific applications, and efforts to commercialize boric-acid based lubricants for metal-forming applications. To a lesser degree, we also are involved with projects to evaluate/assess the tribological properties of NFC, ultrananocrystalline diamond coatings for micro-electromechanical devices, and seal applications.

The following sections describe in greater detail the Tribology Section’s research strengths and the programs that support activities in these areas. The major strength of the Section lies in its ability to not only develop processes to form novel coatings that are lubricious and wear-resistant, but more important, to perform detailed evaluation of the tribological properties of materials and coatings under a wide range of conditions that simulate those found in various energy-intensive sectors. This combined expertise in surface modification and tribological characterization is unique and allows us to more effectively develop advanced surface modification treatments tailored to specific applications. Another strength is our Section’s ability to characterize microstructural and surface chemistry evolution of materials and coatings exposed to tribological environments.