Langmuir-Blodgett Films in High-Pressure Rolling Contacts

Abstract

Ultrathin film interferometry has been used to measure the film thickness of deposited Langmuir-Blodgett layers of stearic acid in a rolling, high pressure, ball on flat contact.

Deposited multilayers up to five monolayers thick have been found to remain in a vertically-oriented configuration in static contact up to Hertzian pressures of at least 0.7 GPa. It has been shown that one deposited monolayer is extremely durable in rolling conditions and continues to show a thickness of at least 2 nm (the vertically-oriented monolayer) even at high speeds and in the presence of supernatant hydrocarbon solvent. Multilayers showed variable behavior. Two monolayers rapidly reduced to one, while three initial monolayers stabilized after rolling at a film thickness corresponding to between one and two monolayers. A four monolayer initial film reduced only slightly in thickness during rolling, to reach a level corresponding to three monolayers.

The results have been interpreted in terms of the transfer of one or more deposited molecular layers from the disc to the ball surface.

Presented at the 54th Annual Meeting in Las Vegas, Nevada May 23–27, 1999

KEY WORDS:

• Friction Modifying Additives
• Boundary Lubrication
• Additive Adsorption
• Additive Deposition
• Optical Interferometry

Notes

Presented at the 54th Annual Meeting in Las Vegas, Nevada May 23–27, 1999