Tribological Behavior of Advanced Base Oil and Grease for Space Applications

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Bearing Fatigue Life Tests in Advanced Base Oil and Grease for Space Applications1. The results of L_<10> life tests showed a long life in order of grease 601EF with base oil 815Z, base oil 2001A, grease R2000 with base oil 2001A and base oil 815Z.2. In the case of oil 815Z, bearing life is hardly related to film parameter A, in contrast to mineral oils, which show a general feature that bearing life increases with increasing A.3. Oil 815Z, having the acetal group (-OCF_2O-), at high shear rate in EHL conjunction the decomposition of oil molecule occurred by mechanical shear and hydrogen fluoride is occurred with the decomposition of acetal group. As a result, the permanent viscosity loss at high Hertzian pressure and hydrogen fluoride generation made shorten bearing life of 815Z oil.4. In the case of grease 601EF with base oil 815Z, thus viscosity loss doesn't occur in ball bearings and lengthen bearings life.5. Under the same A condition, grease 601EF, oil 2001A and grease R2000 with the lower friction coefficient under boundary lubrication has the longer life than paraffinic mineral base oil.Viscosity Loss in PFPE Lubricant for Space Applications under EHL conditions1. The viscosity loss occurred in 815Z fluid under EHL conditions. Permanent viscosity loss and temporary viscosity loss are observed.2. Permanent viscosity loss of 815Z fluid occurred rapidly with time at mean contact pressure of 1.95 GPa to 2.67 GPa. When mean contact pressure decreased, degree of viscosity loss decreased gradually.3. The fluid contains acetal group (-OCF_2O-), which the cause of permanent viscosity loss by decomposition of molecule under the high-pressure conditions.4. Viscosity loss increases with the change of phase from liquid to elastic-plastic solid.5. In the inlet region of EHL test, 815Z fluid showed temporary viscosity loss with lower film thickness.