Surface Films and Soluble Degradation Products Formed in a PFPAE Fluid and Their Implications to the Wear of Steel

Abstract

The soluble degradation products were generated in a linear perfluoropolyalkylether (PFPAE) fluid in boundary lubrication. Perfluoropolyalkylether carboxylic acid species were found in the residual fluids from the sliding tests by vibration spectroscopy. Surface-bound organic and inorganic reaction products were identified by vibration microspectroscopy with a grazing angle objective attachment and X-ray photoelectron spectroscopy (XPS), respectively. Inorganic surface films were found to be composed primarily of FeF₃. A monodentate perfluorocarboxylate surface species was found on the sliding surfaces in 50° and 100°C tests but not found in 150°C tests. The higher friction and wear in 150°C tests as compared to 50° and 100°C tests were attributed to the absence of the perfluorocarboxylate species over the sliding surfaces at high temperatures.

Presented at the 50th Annual Meeting in Chicago, Illinois May 14–19, 1995

KEY WORDS:

• Boundary Lubrication
• Lubricant Degradation
• Synthetic Lubricants
• Surface Films
• Surface Analytical Techniques
• Wear

Notes

Presented at the 50th Annual Meeting in Chicago, Illinois May 14–19, 1995