Rolling contact testing of vapor phase lubricants .1. Material evaluation

Material screening tests have been performed with four candidate vapor phase lubricants under rolling contact conditions at bearing test temperatures of 370 degrees C. The lubricants evaluated were t-butyl phenyl phosphate (TBPP), polyalphaolefin (PAO), cyclophosphazene (X-1P), and PAO blended with 15 percent TBPP (PAO+). Factorial analyses were used to separate the effects of lubricant; bearing steel, T15 vs. thin dense chrome-coated T15; cage material, AISI 4340 vs. Monel 400; and ball material, T15 vs. NBD 200 Si3N4. Response variables included in the analyses were the bearing friction coefficient, wear rate, and life under accelerated conditions. The type of lubricant was significant at the 90 percent confidence level for all three response variables, with the PAO+ and TBPP showing the best results. In general, bearing materials containing Fe showed improved performance over materials which do not contain Fe at the bearing surface.