Invited Paper TR+AS-MoM3
Friction in Full View

Monday, October 28, 2013, 9:00 am, Room 203 C

Friction is a pervasive problem, by some estimates consuming about 5% of the GDP of the economies of the developed world, and a recent analysis has indicated that about one third of the fuel energy in automobiles goes to overcoming frictional losses. While the importance of minimizing friction can be traced back at least as far as the tomb of Tehuti-Hetep, circa 1880 B.C, where a man can be seen pouring a lubricant to assist moving a statue, there are still many unknowns in the field of tribology which encompasses friction as well as other critical processes such as wear and lubrication. For many of the phenomena in tribology there are still numerous unknowns, due in large part to what has been called the buried interface problem. The triboactive layer, is almost always hidden by the materials on both sides of it so the exact details of what is occurring are often hidden, only accessible by post-facto analyses and sometimes a matter for debate. While there have been several attempts to image the triboactive layer directly at the atomic scale dating from the original work by Gane and Bowden, progress has been slow. Over the last few years we have been developing both models from a materials science viewpoint via dislocations as well as in-situ techniques for imaging the buried interface. Related to this (perhaps not obviously) we have recently become involved in understanding the nanoscale tribology of hip replacements, including the perhaps surprising observation of a graphitic layer in-vivo that appears to play a major role in reducing implant failures.This talk will focus upon some of the recent results, ranging from more basic observation such as connecting wear fragment size and a new layer-by-layer wear mechanism to the standoff distance of interfacial dislocations through the formation of graphitic materials in-vivo as well as some direct observations of wear and sliding at the atomic scale.