1. Wear
   
   1. Wear of Mechanical Systems
      
   2. Wear of nanoComposites
      
2. Friction and Lubrication
   
   1. In Situ Tribology
      
   2. Gas Surface Interactions
      
3. Biomaterials Tribology
   
   1. Wear of Total Knee Replacements
      
   2. Hydrogels
      

he contact between macroscopic surfaces occurs on asperities, which are irregularly shaped protuberances existing on all engineering surfaces.  Like fractals, these surface features occur across all length scales.  As our understanding of these contacts increases, it is readily apparent that the nanoscale interactions dominate the macroscopic tribological behaviors.  It is critically important to evaluate the nanotribology of tribological surfaces to gain further fundamental understanding of the chemical, physical, and morphological processes that govern friction and wear of macroscopic contacts. The movies and tribometer described below are our first efforts to monitor surface evolution during macroscopic wearing events.

In Situ Surface Profilometry with Reciprocating Tribometry

This tribometer can operate from 100mN - 5N loads up to about 25 mm/s sliding speed. The stroke length can be about 50 mm although this is very sample dependent. It uses a 6 channel load cell and has very low <1% uncertainties on the friction coefficient. The environment chamber is made from polycarbonate, and the environment can be controlled to better than 100 ppm oxygen with a variety of gases. In addition to friction coefficient, temperatures, relative humidity, and contact resistance are all measured continuously (upto 100 amps can be applied to the contacts). The scanning white light interferometer (ZYGO) has an objective that penetrates into the chamber and can measure a single location repeatedly during testing. The surface is paused in order to take scans.

Stainless Steel
3N load (open air environment)

Copper Brushes
0.5N load (wet CO2 Environment)

1740 W. STUKELEY Stonehenge iv. 21 Eleven of them are standing in situ. 1817 Edin. Rev. Mar. 180 Granite and clay slate are those [rocks] alone which appear in situ. 1845 J. C. ATKINSON in Proc. Berw. Nat. Club II. No. 13. 134 We shall find it in situ close by. 1894 Nation (N.Y.) 31 May 405/1 What actually remains in situ is the walls of the foundations. 1912 Proc. Amer. Philos. Soc. LI. 490 In situ forests occur frequently in shale beds. 1940 Archit. Rev. LXXXVII. 102/2 The foundations to receive the superstructure are formed of concrete in-situ posts. 1968 Daily Tel. 4 Nov. 9/6 Constructed entirely in in-situ concrete..it resembles a fortified gateway to the main hospital buildings. 1971 Nature 24 Dec. 432/1 The Department of the Environment, which has responsibility for in situ historical monuments in England.

Oxford English Dictionary

Where observation is concerned, chance favors only the prepared mind.

Louis Pasteur

It's just effort ...