The development and application of the spacer layer imaging method for measuring lubricant film thickness

Abstract This paper reviews the historical development of optical interferometry as applied to the study of lubricant films. The technique was first applied to lubricated contacts in the 1960s, when it played an important role in the validation of the elastohydrodynamic theory of lubrication. Initially the method was not suited to the study of mixed and boundary lubrication because it could not measure film thicknesses of less than about 50 nm. In the 1970s, however, this limitation was partially overcome by the use of a spacer layer and this, coupled in the early 1990s with spectrometric analysis of the interfered light, enabled films down to just 1 nm thick to be measured in lubricated contacts, well within the boundary lubrication regime. Recently a number of workers have applied colorimetric image analysis to optical interference images to enable accurate three-dimensional maps of film distribution in lubricated contacts to be determined. This approach, coupled with the use of a spacer layer, has led to the spacer layer imaging method, which can map film thickness in boundary and mixed lubricated contact. Some recent applications of this technique are described.

[1]  Hugh Spikes,et al.  Lubricant Film Thickness in Rough Surface, Mixed Elastohydrodynamic Contact , 2000 .

[2]  J. S. Courtney‐Pratt,et al.  The area of real contact and the shear strength of monomolecular layers of a boundary lubricant , 1955, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[3]  H. Spikes,et al.  Elastohydrodynamic properties of water in oil emulsions , 1977 .

[4]  C. Allen,et al.  Boundary layer lubrication: monolayer or multilayer , 1969 .

[5]  David Tabor,et al.  The direct measurement of normal and retarded van der Waals forces , 1969, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[6]  H. Spikes,et al.  Molecular scale liquid lubricating films , 2000 .

[7]  Philippa Cann,et al.  Understanding grease lubrication , 1996 .

[8]  R. Gohar,et al.  The Mapping of Elastohydrodynamic Contacts , 1967 .

[9]  Hugh Spikes,et al.  Fractionation of liquid lubricants at solid surfaces , 1996 .

[10]  N. Technical.  OPTICAL ANALYSIS OF BALL BEARING STARVATION , 1970 .

[11]  P. L. Wong,et al.  Optical characteristics of thin film coating and measurement of its thickness , 1997 .

[12]  A. Cameron,et al.  Optical Elastohydrodynamic Fluid Testing , 1972 .

[13]  Hugh Spikes,et al.  Mechanisms of oiliness additives , 2000 .

[14]  D. Tabor,et al.  The extrusion of liquids between highly elastic solids , 1971, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[15]  Miroslav Liška,et al.  Differential colorimetry: tool for evaluation of chromatic interference patterns , 1997 .

[16]  H. Spikes,et al.  Behaviour of colloidally-dispersed solid particles in very thin film lubricated contacts , 2000 .

[17]  J. Israelachvili,et al.  Dynamic Properties of Molecularly Thin Liquid Films , 1988, Science.

[18]  Roland Larsson,et al.  A Hybrid Film Thickness Evaluation Scheme Based on Multi-Channel Interferometry and Contact Mechanics , 2000 .

[19]  Hugh Spikes,et al.  The Development of a Spacer Layer Imaging Method (SLIM) for Mapping Elastohydrodynamic Contacts , 1996 .

[20]  W. Hardy.  II. Note on static friction and on the lubricating properties of certain chemical substances , 1919 .

[21]  Irving P. Langmuir,et al.  Über einige neue Methoden zur Untersuchung von monomolekularen Filmen , 1935 .

[22]  J. S. Courtney‐Pratt.  Direct Optical Measurement of the Length of Organic Molecules , 1950, Nature.

[23]  J. Molimard,et al.  New tools for the experimental study of EDH and limit lubrications , 1999 .

[24]  A. Cameron,et al.  Evaluation of Lubricants Using Optical Elastohydrodynamics , 1968 .

[25]  Enrico Ciulli,et al.  Lubricant film thickness and shape using interferometry and image processing , 1997 .

[26]  G. Dalmaz,et al.  Film Thickness in Starved EHL Point Contacts , 1998 .

[27]  A. Cameron,et al.  Fluid Film Interferometry in Lubrication Studies , 1967, Nature.

[28]  P. Cann.  Grease lubricant film distribution in rolling contacts , 1997 .

[29]  R. Gohar,et al.  Oil Film Thickness and Rolling Friction in Elastohydrodynamic Point Contact , 1971 .

[30]  H. Spikes,et al.  Film Formation by Colloidal Overbased Detergents in Lubricated Contacts , 2000 .

[31]  Hugh Spikes,et al.  Central and minimum elastohydrodynamic film thickness at high contact pressure , 1997 .

[32]  Hugh Spikes,et al.  Film-Forming Properties of Zinc-Based and Ashless Antiwear Additives , 2000 .

[33]  A. Cameron,et al.  A study of ultra-thin lubricant films using an optical technique , 1967 .

[34]  R. Gohar,et al.  Theoretical and experimental studies of the oil film in lubricated point contact , 1966, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[35]  Olov Marklund,et al.  Measuring Lubricant Film Thickness with Image Analysis , 1994 .

[36]  S. Wen,et al.  Thin film lubrication. Part I. Study on the transition between EHL and thin film lubrication using a relative optical interference intensity technique , 1996 .

[37]  L. D. Wedeven,et al.  Elastohydrodynamic film thickness measurements of artificially produced surface dents and grooves. [on fatigue failure of bearings] , 1978 .

[38]  Paper XI(i) Properties of ultra-thin lubricating films using wedged spacer layer optical interferometry , 1987 .

[39]  Hugh Spikes,et al.  The Measurement and Study of Very Thin Lubricant Films in Concentrated Contacts , 1991 .

[40]  H. Spikes,et al.  Friction and Wear Behavior of Zinc Dialkyldithiophosphate Additive , 2000 .

[41]  Hugh Spikes,et al.  The Behavior of Colloidal Solid Particles in Elastohydrodynamic Contacts , 2000 .

[42]  R. Gohar,et al.  Optical Measurement of Oil Film Thickness under Elasto-hydrodynamic Lubrication , 1963, Nature.

[43]  M. Kirk.  Hydrodynamic Lubrication of ‘Perspex’ , 1962, Nature.

[44]  A. Jackson,et al.  An Interferometric Study of the EHL of Rough Surfaces , 1976 .

[45]  H. Spikes.  Boundary Lubrication and Boundary Films , 1993 .

[46]  Measurement of the Density of Base Fluids at Pressures to 2.2 GPa , 1986 .

[47]  D. M. Sanborn,et al.  Fluid Rheological Effects in Sliding Elastohydrodynamic Point Contacts With Transient Loading: 1—Film Thickness , 1971 .