Film forming behavior in thin film lubrication at high speeds

He Liang,Jianbin Luo,Dan Guo

doi:10.1007/s40544-017-0159-5

Abstract

The film forming condition may transit into thin film lubrication (TFL) at high speeds when it is under severe starvation. Central film thicknesses and film thickness profiles are obtained via a technique of relative optical interference intensity. These profiles show a critical film thickness lower than which the absolute values of the film thickness gradient against speed or time decrease. It is possible to be in the thin film lubrication mode under such conditions. The high speed flow drives the lubricant molecules to rearrange in TFL and critical film thickness higher than 100 nm is achieved. The viscosity is one of the main factors controlling the decreasing rate and the critical film thickness. This paper is designed to investigate the thin film lubrication behavior at high speeds.

Highlights

In a nanoscale the lubrication behavior may be determined by both physical characteristics of the lubricant and the interaction between lubricant molecules and solid surfaces
It is defined as thin film lubrication (TFL) [1−4], which is a transition between elastohydrodynamic lubrication (EHL) [5−7] and boundary lubrication (BL) [8, 9]
3.1 The film forming under severe starvation at high speeds

Summary

Introduction

In a nanoscale the lubrication behavior may be determined by both physical characteristics of the lubricant and the interaction between lubricant molecules and solid surfaces. In TFL ordered layers are formed essentially by aligned molecules driven by shearing or flowing in a confined space and these layers determine the behavior of the lubrication as has been proven both theoretically and experimentally [1−4, 10, 11]. It results in higher effective viscosity as well as thicker film thickness in TFL compared with that of absorbed layers in BL as long as the shear rate is less than the critical value of approximately 106–108 s−1 for shear thinning in confined lubricants [12]. Some factors like an external electrical field that have the ability to change the orientation of molecules can change the film thickness and friction characteristics in TFL [13]

Results

Discussion

Conclusion