表面力仪及油性添加剂薄膜流变特性

为研究超薄润滑膜的摩擦特性和添加剂的影响 ,采用自制的表面力仪进行了润滑剂基础油和油性添加剂的薄膜流变实验。结果表明 :当膜厚减薄到纳米量级时 ,润滑油呈现非牛顿剪切响应 ,即剪切稀释现象 ,其等效粘度随着膜厚变薄而增加 ,并在某个临界膜厚处急剧上升。加入添加剂后 ,润滑油等效粘度降低 ,临界膜厚变小 ,说明薄膜流变特性与界面的摩擦状况有关。指出油性添加剂的功能在于形成摩擦系数小但厚度较薄的吸附层 ,与界于壁面间的润滑流体构成夹层结构 ,从而较好地解释了实验规律

Surface force apparatus and thin film rheology for additive-treated lubricant

A surface force apparatus to experimentally study the thin film rheology of an additive treated lubricant. Results show that the lubricant, expected to be a Newtonian fluid in its bulk state, exhibits nonlinear shear response when the film thickness is reduces to the nano meter scale. The effective viscosity of the lubricant increases as the film thickness decreases, approaching infinity when the film thickness reaches a critical point. When mixed with oily additives, the lubricant has a lower effective viscosity and a smaller value of the critical film thickness, indicating that the thin films rheology is related to tribological properties of the interfaces. A sandwich model for thin film rheology provides a better understanding of the experimental phenomena.