Investigation of Tribo-Chemistry by Means of Stable Isotopic Tracers, Part 2: Lubrication Mechanism of Friction Modifiers on Diamond-Like Carbon

Abstract

A solution of glycerol monooleate (GMO) in polyalphaolefin (PAO) considerably reduced the friction between the steel and the diamond-like carbon (DLC) under boundary conditions. The combination of the material-oil-additive is of importance. Model additives composed of a stable isotope ( ² H or ¹³ C) were employed to trace the additive molecule by time-of-flight secondary ion mass spectroscopy (TOF-SIMS). It was found that the additive interacted with DLC surfaces in the form of an ester. Inclusion of PAO in the boundary film on DLC was found by TOF-SIMS analysis.The utility of the isotopic tracer technique in tribo-chemistry was demonstrated in this study.

KEY WORDS:

• Friction Modifying
• Boundary Lubrication–Chemistry
• Materials–Diamond Like Carbon
• Surface Analysis

Acknowledgments

Presented at the STLE Annual Meeting in Calgary, Alberta, Canada

May 7-11, 2006

Manuscript approved May 22, 2007

Review led by Elaine Yamaguchi