A report describes research on selected compounds as additives to perfluoroalkyether (PFPAE) fluids that are used as synthetic lubricants for metal parts. Additives are needed to inhibit both thermo-oxidative degradation of, and corrosion of metals by, the PFPAE fluids in the presence of oxidizing atmospheres. [An earlier phase of this research was reported in "Performance of Perfluoroalkylether Lubricant System" (LEW-15603), NASA Tech Briefs, Vol. 19, No. 9 (September 1995), page 123.] The phase of research described in the present report included (1) synthesis of novel phospha-s-triazines, phosphate esters, and related additive compounds and (2) evaluation of these and previously available additives with respect to degradation- and corrosion-inhibiting behavior and thermal and hydrolytic stability, in an effort to develop a data base of optimum PFPAE/additive/alloy combinations. The other materials included in the study were six different alloys and four commercial PFPAEs. None of the additives tested was found to undergo hydrolysis at a temperature of 100 °C. The phosphate esters were found to be the most effective and, in particular, were fully effective in arresting the degradation of the PFPAEs in the presence of metal alloys and oxygen at temperatures up to 300 °C. In an overall rating, the additives in order of decreasing effectiveness were found to be phosphates > phosphate/diester mixture > phosphine > phospha-s-triazines.
This work was done by K. J. L. Paciorek of Lubricating Specialties Co. forLewis Research Center. To obtain a copy of the report, "Phospha-s-Triazines and Related Compositions of Improved Hydrolytic and Thermal Stability," access the Technical Support Package (TSP) free on-line at www.techbriefs.com under the Materials category, or circle no. 195 on the TSP Order Card in this issue to receive a copy by mail ($5 charge).
Inquiries concerning rights for the commercial use of this invention should be addressed to
NASA Lewis Research Center
Commercial Technology Office
Attn: Tech Brief Patent Status
Mail Stop 7-3
21000 Brookpark Road
Refer to LEW-16561.