Rolling Contact Fatigue Testing of a 3 cSt Polyolester Lubricant with and Without TCP and DODPA/PANA at 177 °C

Abstract

A rolling contact fatigue (RCF) tester was used to quantify the effects of additives on the tribological performance of 3 cSt polyol ester type gas turbine engine lubricants. The RCF tests were conducted on partially and fully formulated polyolester lubricants at 177 °C with M50 bearing elements. Polyolester base-stock, base-stock +1% tricresyl phosphate (TCP), base-stock +1% dioctyl-diphenyl amine (DODPA) +1% phenyl-α-napthyl amine (PANA), base stock +1% TCP +1% DODPA +1% PANA and a commercially formulated MIL-L-7808J containing the additives TCP and DODPA/PANA were tested. The post test rod samples were characterized for wear and oil samples were evaluated for changes in viscosity and acid number. The formulations without anti-oxidant resulted in heavy coking and significant increase in viscosity and total acid number (TAN). The formulations without TCP resulted in significantly higher wear and lower RCF life. Overall, TCP was found to have substantial positive impact on fatigue and wear resistance. Somewhat surprisingly, DODPA/PANA had a slight negative affect on fatigue and wear. The oil with TCP and DODPA/PANA added to the base-stock performed the same as the fully formulated MIL-L-7808J.