Effect of surface contamination of the UHV friction behavior of the Cu(111)/Cu(111) interface

Conference · Fri Dec 01 04:00:00 EST 1995

OSTI ID:126112

McFadden, C F ^[1]; Gellman, A J ^[2]

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1. Univ. of Illinois, Urbana-Champaign, IL (United States)
2. Carnegie Mellon Univ., Pittsburgh, PA (United States)

An ultrahigh vacuum (UHV) tribometer has been used to study the tribological behavior of two Cu(111) surfaces modified with controlled levels of surface contamination in the form of carbon and sulfur. The tribometer is designed such that both Cu(111) samples may be prepared, characterized using auger electron spectroscopy (AES) and low energy electron diffraction (LEED), and brought into sliding contact all under UHV without exposure to the atmosphere. The shearing behavior of clean Cu(111) surfaces is characterized by high, erratic friction coefficients ({mu}{sub s} = 4.6 {+-} 1.1). For modified surfaces the friction coefficient decreases montonically with increasing, submonolayer coverages of carbon and sulfur. This sensitivity to trace levels of atomic adsorbates is in stark contrast with the lubricating ability of molecular adsorbates of ethanol and trifluoroethanol, which have no influence on the friction coefficient until coverages exceeding one monolayer. This suggests that the lubrication of metallic interfaces may not result from the presence of intact molecular species but instead from that of inorganic films formed during lubricant decomposition.

• OSTI ID: 126112
• Report Number(s): CONF-950402--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COPPER
ETHANOL
FLUORINATED ALIPHATIC HYDROCARBONS
FRICTION
LUBRICATION
TRIBOLOGY