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Shear property of oil film containing oiliness additive in narrow gap measured with newly‐developed parallel‐disk viscometer supported by aerostatic bearing
Author(s) -
Hirayama Tomoko,
Shibata Shun,
Harada Tomoyuki,
Hashimoto Yusuke,
Yamashita Naoki
Publication year - 2020
Publication title -
lubrication science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.632
H-Index - 36
eISSN - 1557-6833
pISSN - 0954-0075
DOI - 10.1002/ls.1485
Subject(s) - viscometer , lubrication , base oil , materials science , shear force , slip (aerodynamics) , shear (geology) , composite material , bearing (navigation) , shear stress , chemistry , viscosity , scanning electron microscope , thermodynamics , physics , cartography , geography
The shear force of oil film containing an oiliness additive in a narrow gap was measured with a newly developed parallel‐disk viscometer supported by an aerostatic thrust bearing. To evaluate viscometer performance, the shear force of pure base oil was first measured using an oleophobic coated disk. Using the coated disk resulted in interfacial slip between the disk surface and oil, which significantly reduced the shear force compared with that when a noncoated disk was used. Next, the shear force of base oil containing an oiliness additive was measured without using the coated disk. Again it was significantly reduced, especially when the gap was less than 1 μm. The degree of reduction depended on the oiliness additive used. These results demonstrate that an oiliness additive can cause interfacial slip, resulting in friction reduction even in a hydrodynamic lubrication regime with a submicrometer gap.