Characteristics of a liquid lubricant film at the nanometer scale are discussed in the present paper. The variations of the film thickness in a central contact region between a glass disk and a super-polished steel ball with lubricant viscosity, rolling speed, substrate surface tension, running time, load, etc. have been investigated. Experimental results show that the variation of film thickness in the thin film lubrication (TFL) regime is largely different from that in the elastohydrodynamic lubrication (EHL) regime. The critical transition point from EHL to TFL is closely related to lubricant viscosity, surface energy of substrates, and so on. The film in TFL is much thicker than that calculated from the Hamrock-Dowson formula. An unusual behavior of the lubricant film has also been observed when the effect of the running time on the film thickness is considered. The time effect and the formation mechanism of the enhanced film in the running process have been discussed.

1.
Adamson, A. W., 1985, The Physical Chemistiy of Surfaces, Interscience, Fourth Ed., New York.
2.
Allen
C. M.
and
Drauglis
E.
,
1969
, “
Boundary Layer Lubrication: Monolayer or Multilayer
,”
Wear
, Vol.
14
, pp.
363
384
.
3.
Alsten
J. V.
, and
Granick
S.
,
1989
, “
Friction Measured with a Surface Forces Apparatus
,”
Trib. Trans.
, Vol.
32
, pp.
246
250
.
4.
Bhushan, B., 1996, Tribology and Mechanics of Magnetic Storage Devices, Second Edition, Springer-Verlag, New York, pp. 765–769.
5.
Chen
Y. L.
,
Kuhl
T.
, and
Israelachvili
J.
,
1992
, “
Mechanism of Cavitation damage in thin liquid film: Collapse Damage vs. Inception Damage
,”
Wear
, Vol.
153
, pp.
31
51
.
6.
Derjaguin, B. V., 1987, Surface Force, Plenum Publishing, New York, pp. 25–52.
7.
Gao
G.
, and
Spikes
H. A.
,
1997
, “
The Control of Friction by Molecular Fractionation of Base Fluid Mixtures at Metal Surface
,”
STLE, Trib. Trans.
, Vol.
40
(
3
), pp.
461
469
.
8.
Granick
S.
,
1991
, “
Motions and Relaxation of Confined Liquid
,”
Science
, Vol.
253
, pp.
1374
1379
.
9.
Hamrock, B. J. and Dowson, D., 1981, Ball Bearing Lubrication—the Elastohydrodynamic of Elliptical Contact, Wiley-Interscience, New York.
10.
Hamrock, B. J., 1994, Foundamentals of fluid Film Lubrication, McGraw-Hill, New York, pp. 470—475.
11.
Huang
P.
,
Luo
J. B.
,
Zhu
Q.
, et al.,
1994
, “
NGY-2 Nano-Film Thickness Measurer
,”
Chinese J. of Trib.
, Vol.
14
, pp.
175
179
.
12.
Hu
Y. Z.
,
Wang
H.
,
Guo
Y.
, and
Zheng
L. Q.
,
1996
a, “
Simulation of Lubricant Rheology in Thin Film Lubrication, Part 1: Simulation of Poiseuille Flow
,”
Wear
, Vol.
196
, pp.
243
248
.
13.
Hu
Y. Z.
,
Wang
H.
,
Guo
Y.
, and
Zheng
L. Q.
,
1996
b, “
Simulation of Lubricant Rheology in Thin Film Lubrication, Part II: Simulation of Couette Flow
,”
Wear
, Vol.
196
, pp.
249
253
.
14.
Iliuc, L., 1980, Tribology of Thin Layers, Elsevier Scientific Publishing, pp. 58–59.
15.
Israelachvili
J. N.
, and
Tabor
D.
,
1972
, “
The Measurement of van der Waals Dispersion Force in the Range of 1.5 nm to 130 nm
,”
Proc. R. Soc
, (London), Vol.
A331
, pp.
19
38
.
16.
Israelachvili
J. N.
,
1973
, “
Thin Film Studies Using Multiple Beam Interferometry
,”
J. of Colloid and Interface Sci.
, Vol.
44
(
2
), pp.
259
271
.
17.
Israelachvili
J.
, and
Adams
G. E.
,
1978
, “
Measurement of Friction between Two Mica Surface in Aqueous Electrolyte Solutions in the Range 0-100 nm
,”
Chem. Soc. J., Faraday Trans. I
, Vol.
74
, pp.
975
1001
.
18.
Israelachvili, J., 1992, Intermolecular and Surface Force, 2nd Edition, Academic Press.
19.
Johnston
G. J.
,
Wayte
R.
, and
Spikes
H. A.
,
1991
, “
The Measurement and Study of Very Thin Lubricant Films in Concentrate Contact
,”
STLE, Trib. Trans.
, Vol.
34
, pp.
187
194
.
20.
Luengo
G.
,
Israelachvili
J.
, and
Grank
S.
,
1996
, “
Generalized Effects in Confined Fluids: New Friction Map for Boundary Lubrication
,”
Wear
, Vol.
200
, pp.
328
325
.
21.
Luengo
G.
,
Schmitt
F.
,
Hill
R.
, and
Israelachvili
J.
,
1997
, “
Thin Film Rheology and Tribology of Confined Polymer Melts: Contrasts with Bulk Properties
,”
Macromolecules
, Vol.
30
(
8
), pp.
2482
2494
.
22.
Luo, J. B., 1994, “Study on the Measurement and Experiments of Thin Film Lubrication,” Ph.D. thesis, Tsinghua University, Beijing, China.
23.
Luo
J. B.
,
Wen
S. Z.
, and
Huang
P.
,
1996
a, “
Thin Film Lubrication, Part I: The Transition between EHL and Thin Film Lubrication
,”
Wear
, Vol.
194
, pp.
107
115
.
24.
Luo
J. B.
, and
Wen
S. Z.
,
1996
b, “
Study on the Mechanism and Characteristics of Thin Film Lubrication at Nanometer Scale
,”
Science in China (Series A)
, Vol.
35
(
12
), pp.
1312
1322
.
25.
Luo
J. B.
, and
Wen
S. Z.
,
1998
, “
Progress and Problems in Nano-tribology
,”
Chinese Science Bulletin
, Vol.
43
(
7
), pp.
369
378
.
26.
Matsuoka
H.
, and
Kato
T.
,
1997
, “
An Ultralthin Liquid Film Lubrication Theory—Calculation Method of Solvation Pressure and Its Application to the EHL Problem
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
119
, pp.
217
226
.
27.
Robbins, M. O., Thompson, P. A., and Grest, G. S., 1993, “Simulations of Nanometer-Thick Lubricating Film,” MR Bulletin, May, pp. 45–49.
28.
Robert, C. W., 1977, CRC Handbook of Chemistry and Physics, CRC Press, 58th Edition, pp. F-25–F-48.
29.
Ruan
J.
, and
Bhushan
B.
,
1994
a, “
Atomic-Scale Friction Measurements Using Friction Force Microscope: Part I: General Principles and New Measurement Techniques
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
116
, pp.
378
388
.
30.
Ruan
J
. and
Bhushan
B.
,
1994
b, “
Frictional Behavior of Highly Oriented Pyrolytic Graphite
,”
J. Appl. Phys.
, Vol.
76
, pp.
8117
8120
.
31.
Thompson
P. A.
,
Grest
G. S.
, and
Robbin
M. O.
,
1992
, “
Phase Transitions and Universal in Confined Films
,”
Physical Review Letters
, Vol.
68(23)
, pp.
3448
3451
.
32.
Tichy
J. A.
,
1995
a, “
Modeling of thin film lubrication
,”
STLE Trib. Trans.
, Vol.
38
, pp.
108
118
.
33.
Tichy
J. A.
,
1995
b, “
A Surface Layer Model for Thin Film Lubrication
,”
STLE Trib. Trans.
, Vol.
38
, pp.
577
582
.
34.
Tichy
J. A.
,
1995
c, “
A Porous Media Model of Thin Film Lubrication
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
117
, pp.
16
21
.
35.
Wen, S. Z., 1993, “On Thin Film Lubrication,” Proc. of Lit Inter. Symp. on Trib., International Academic Publisher, Beijing, pp. 30–37.
36.
Wen, S. Z., and Yang, P. R., 1992, Elastohydrodynamic Lubrication, Tsinghua University Publisher, Beijing, pp. 261–288.
37.
Wong
P. L.
,
Wang
R. Y.
, and
Lingard
S.
,
1996
, “
Pressure and Temperature Dependence of the Density of Liquid Lubricant
,”
Wear
, Vol.
201
, pp.
58
63
.
38.
Yoshizawa
H.
,
McGuiggan
P.
, and
Israelachvili
J.
,
1993
, “
Identification of a Second Dynamic State During Stick-Slip Motion
,”
Science
, Vol.
259
, pp.
1305
1308
.
This content is only available via PDF.
You do not currently have access to this content.