Staff Only
 

Tribology

 
 

Tribology is the science and technology of interacting surfaces in relative motion and all practices related thereto. In other words, it is an interdisciplinary field which concerns the friction, lubrication, wear, and surface durability of materials and mechanical systems. Tribology is an important, enabling subject which is closely-tied to progress in transportation, manufacturing, energy conversion, agriculture, and mining industries. Typical tribological applications include bearings, gears, bushings, brakes, clutches, chains, human body implants and protheses, floor tiles, seals, piston engine parts, sports equipment (for example, skis and skates), and cosmetics (for example, lubrication in shampoo and skin creams). The basic disciplines involved in tribology are:

  • chemical engineering
  • contact mechanics 
  • lubrication engineering
  • materials engineering 
  • mechanical engineering
  • metallurgy and ceramics 
  • nano-scale surface physics
  • polymer science 
  • surface chemistry 

The economic cost of wear and friction to the U.S. easily exceeds $100 Billion per annum. The magnitude of the impact of tribology becomes easily apparent considering that $1 Billion per annum is involved in warranty costs for automotive brakes alone. Consider the annual maintenance costs for automobiles, aircraft, trucks, and ships due to worn parts or to oil and grease changes. Friction losses decrease the efficiency of many machines and, if reduced, could preserve dwindling natural resources like coal, oil, and natural gas.

Oak Ridge National Laboratory has had an active tribology research effort since the early 1980's when the Department of Energy established the Energy Conversion and Utilization Technologies (ECUT) Tribology Project and subsequently named ORNL to head one of its three task areas. We conducted ground-breaking research on the use of ceramics for high-temperature engine applications and later conducted the most comprehensive investigation of the friction and wear of intermetallic alloys in the world. A host of materials and surface treatments have been characterized and evaluated for tribological performance over the years. These include:

  • carbon-graphite materials
  • ceramic composites
  • ceramic superconductors 
  • cermets
  • diamond films 
  • hand coatings
  • high-temperature greases
  • high-temperature lubricants 
  • intermetallic alloys
  • metal alloys 
  • metal matrix composites
  • single crystal materials
  • solid lubricants
  • structural ceramics
  • surface-modified polymers 
  • thermally-sprayed coatings

Studies have included sliding, abrasive, and impact wear. Friction and wear results have been supplemented by detailed studies of the surface and subsurface microstructures of materials and how they change during surface contact. Transitions from acceptable to catastrophic wear modes have been mapped in multi-dimensional parameter spaces, and tribological transitions have been studied.

ORNL has been strongly involved in the international tribology and standards communities. Staff members serve on the editorial boards of the journals Lubrication Engineering and Tribology International One staff member developed and edited the 1992 ASM Handbook volume 18 on Friction, Lubrication, and Wear Technology. Staff members have also edited and contributed to numerous technical publications, including several ASTM Special Technical Publications on friction and wear testing strategies. They served as leaders of national committees and international conferences.

We maintain a well-equipped laboratory with both commercially-manufactured and custom designed tribology testing equipment. Some instruments simulate engineering applications and others are used for basic studies in friction and wear-science. Our equipment includes:

In addition, we have access to nanoindentation facilities, electron microscopy, atomic force microscopy, surface chemical analysis, x-ray analysis, noncontact surface roughness measurement, and other surface characterization instruments at ORNL.

The various tribology testing instruments described above are available to U.S. industry and universities through the High Temperature Materials Laboratory Tribology User Center (TRUC).

In summary, ORNL has both the equipment, and the expertise to conduct comprehensive investigations of the relationship between materials structure and their friction and wear behavior.

Contact: Peter J. Blau

 
 
   

 Oak Ridge National Laboratory