A novel approach to measures lip-length of thin lubricant films under high pressures

Abundant evidence of boundary slip at liquidsolid interfaces has been presented by experiments and theoretical analyses. Recent research reveals that the boundary slip effect of lubricants can be obvious in small confined gaps, even with simple Newtonian fluids. Therefore, it is appropriate to asic if there is boundary slip of thin highiy pressurized iubricant films in EHL contacts, and, if so, how to quantify it. This paper proposes a method for measuring the slip-length of iubricant films within a smaH gap under high pressure. Measurement principies have been addressed in detaiis in the paper. The idea makes use of the phenomenon whereby a tiny quantity of iubricant can be entrapped and forms a dimpie film by impacting a steei baH against a iubricated giass piate. The slip-length can be extracted from the reiative movement of the dimpie against the solid surfaces. Case experiments are aiso presented to validate the feasibility of the method. © 2011 Eisevier Ltd.