Effect of Lubricant Extreme-pressure Additives on Rolling-element Fatigue Life
National Aeronautics and Space Administration, 1973 - Lubrication and lubricants - 21 pages
The effects of surface active additives on rolling-element fatigue life were investigated with the five-ball fatigue tester at conditions where classical subsurface initiated rolling-element fatigue is the sole mode of failure. Test balls of AISI 52100, AISI M-50, and AISI 1018 were run with an acid-treated white oil containing either 2.5 percent sulfurized terpene, 1 percent didodecyl phosphite, or 5 percent chlorinated wax. In general, it was found that the influence of surface active additives was detrimental to rolling-element fatigue life. The chlorinated-wax additive significantly reduced fatigue life by a factor of 7. The base oil with the 2.5 percent sulfurized-terpene additive can reduce fatigue life by as much as 50 percent. No statistical change in fatigue life occurred with the base oil having the 1 percent didodecyl-phosphite additive. The additives used with the base oil did not change the ranking of the bearing steels where rolling-element fatigue life was of subsurface origin.
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2.5 percent sulfurized 7-millimeter acid-treated white oil additive significantly reduced additives on rolling-element AISI 1018 steel antiwear additives base oil bearing steels change in fatigue chlorinated-wax additive significantly combined confidence number contact angle detrimental to rolling-element EHD film thickness Elastohydrodynamic Film Thickness element fatigue EP additives erence failure index fatigue life occurred five-ball fatigue tester included a maximum initiated rolling-element fatigue Lewis Research Center lower test balls Lubricant additives M-50 and AISI materials and lubricant maximum Hertz stress mode of failure NASA TN percent chlorinated wax percent didodecyl phosphite percent didodecyl-phosphite additive percent sulfurized terpene race temperature ranking of bearing rheology Rolling-Element Bearings Rolling-element fatigue tests shaft speed significantly reduced fatigue steel ball materials subsurface initiated rolling-element subsurface origin surface active additives surface distress type temperature of 340 test lubricant tests of reference Three steel ball upper test ball upper-ball stress cycles viscosity white oil containing Zaretsky