Adsorption and friction coefficient in boundary lubrication

Summary form only given. Driven by the economical impact of friction phenomena, there has been considerable interest in understanding the relationship between friction reduction and the adsorption of friction modifiers on solid surfaces. We have used sum-frequency generation (SFG) spectroscopy with a high frequency reciprocating rig (HFRR) to investigate the adsorption of a friction modifier to an iron oxide substrate and its relationship to friction reduction. Our results convincingly demonstrate a strong correlation between the adsorption of friction modifier and the reduction in friction coefficient. This is the first direct experimental correlation between the friction reduction and the surface coverage and strongly supports the theoretical model developed by Rowe and more recently by Jahanmir and Beltzer.