A report describes experiments on the wear-reducing performances of six additives to perfluoropolyether (PFPE)-based fluids in the boundary-lubrication regime. The additives were a phosphate, a thiophosphate, a β-diketone, a benzothiazole, an amide/thiol, and a sulfite. Each additive was dissolved, at a concentration of 1 weight percent, in a PFPE based on hexafluoropropene oxide. The resulting formulation was exposed to the boundary-lubrication regime in a four-ball vacuum tribometer at a temperature ≈ 23 °C, an initial Hertzian stress of 3.5 GPa, and a sliding speed of 28.8 m/s. The wear rate for each formulation was determined from the slope of wear volume as a function of sliding distance.

This work was done by William R. Jones, Jr., of Lewis Research Center; Bradley A. Shogrin of Case Western Reserve University; Pilar Herrera-Fierro of Ohio Aerospace Institute; and Tzuhn-Yuan Lin and Hajimu Kawa of Exfluor Research Corp. To obtain a copy of the report, "Evaluation of Boundary-Enhancement Additives for Perfluoropolyethers," access the Technical Support Package (TSP)free on-line at www.techbriefs.com under the Materials category,or circle no. 165 on the TSP Order Card in this issue to receive a copy by mail ($5 charge).

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Refer to LEW-16592.