Tribological Behavior of Advanced Base Oil and Grease for Space Applications

航天用高级基础油和润滑脂中的轴承疲劳寿命试验1。L 10&>寿命试验结果表明，润滑脂的使用寿命依次为601EF基础油815Z、2001a基础油、R2000基础油2001a、815Z.2基础油。在815Z油的情况下，轴承寿命与油膜参数A几乎没有关系，而矿物油则表现出轴承寿命随A.3的增加而延长的一般特征。含缩醛基团(-OCF2O-)的815Z油在高剪切速率下发生机械剪切分解，氟化氢伴随缩醛基团的分解而发生。因此，高赫兹压力下的永久粘度损失和氟化氢的生成使815Z油的轴承寿命缩短。在基础油为815Z的601EF润滑脂的情况下，球轴承不会发生粘度损失，从而延长轴承寿命。在相同的A条件下，601EF润滑脂、2001a润滑脂和R2000润滑脂在边界润滑下的摩擦系数较低的润滑脂比石蜡矿物基础油具有更长的寿命。815Z流体在弹流条件下发生粘度损失。观察到永久粘度损失和暂时性粘度损失。在平均接触压力为1.95~2.67 GPa时，815Z流体的永久粘度损失随时间迅速增加。随着平均接触压力的降低，粘度损失程度逐渐减小。该流体含有缩醛基团(-OCF_2O-)，在高压条件下分子分解导致永久粘度损失。粘度损失随相组成由液态向弹塑性固相转变而增大。在弹流试验的入口区，815Z流体表现出短暂的粘度损失，油膜厚度较小。

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.