表面力仪的改进及超薄膜流变特性的实验研究

在对原表面力仪进行较大改进的基础上 ,以 5 0 0 SN基础油和十六烷为研究对象 ,进行了超薄膜流变特性的实验研究 .结果表明 :在超薄膜润滑条件下 ,5 0 0 SN和十六烷均表现出明显的非牛顿剪切响应 ,即剪切稀释现象 ;摩擦力幅值随剪切速度的增大急剧上升到最大值 ,然后下降至某一固定值附近并产生波动 ;剪切挤压下的临界膜厚小于静态挤压的临界膜厚 ,剪切运动对吸附层有序结构产生破坏作用

Improvement on Surface Force Apparatus and Experimental Study of Rheological Properties of Ultra-thin Films

The previously developed surface force apparatus was reconstructed and improved with a focus on the improvement of the micro-displacement system and optical measurement system. The rheological properties of 500SN and hexadecane thin films were investigated with the improved surface force apparatus. As the results, the ultra-thin films of 500SN and hexadecane exhibited nonlinear shearing response, which was different from that of the Newtonian fluids in their bulk state. In other words, the ultra-thin films of 500SN and hexadecane were characterized by shearing thinning. Moreover, the friction force increases abruptly with increasing shearing velocity at the early stage and then decreases to a smaller value with fluctuation. The critical film thickness in the dynamic pressing test was much smaller than that in the static pressing test, indicating that the shearing movement of the ultra-thin films could lead to destruction of the structure of the adsorbed layer.