机械衰减对锂基润滑脂流变特性的影响

Influence of Mechanical Degradation on Rheological Properties of Lithium Lubricating Greases

采用万次剪切机对一种锂基润滑脂进行不同剪切次数下的剪切,得到衰减程度不同的锂基润滑脂。采用微牵引力试验机对经过机械衰减的锂基润滑脂进行弹流润滑状态下的摩擦力测试,并计算得到润滑脂的流变特性参数。分析不同温度、不同滚动速度和不同载荷下,衰减程度不同的锂基润滑脂的流变特性。结果表明:锂基润滑脂的剪应力随机械衰减程度的增大而增大,其抗剪切性能随机械衰减程度的增大而下降;锂基润滑脂衰减程度越大,速度增加造成的润滑脂剪应力下降程度越大,载荷增加造成的润滑脂剪应力增大的程度越小,温度升高造成的润滑脂剪应力下降的程度越小,即机械衰减程度越大的锂基脂对温度和载荷变化越不敏感,对速度变化较敏感。

The lithium greases with different mechanical degradation were obtained by shearing a lithium lubricating grease with the ten thousand times shearing machine at different shearing times.The friction of the degradated lithium grease in the state of elastohydrodynamic lubrication was measured by mini traction machine,and the rheological parameters were calculated.The rheological behaviors of lithium greases with different mechanical degradation at different temperatures,rolling speeds and loads were analyzed.The results show that with the increasing of the mechanical degradation,the shear stress of the lithium lubricating grease is increased and the friction performance is decreased.The greater the mechanical degradation is,the greater the decrease of the shear stress caused by the increasing of rolling speed,the smaller the increase of the shear stress caused by the increasing of load,and the smaller the decrease of the shear stress caused by temperature rise.That is,the lithium grease with high mechanical degradation is not sensitive to temperature and load change,but sensitive to speed change.