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Rheological properties of high‐viscosity‐index mineral base oils for automotive engine lubricants
Author(s) -
Muraki M.,
Dong D.
Publication year - 2005
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.3010170206
Subject(s) - viscosity index , viscometer , base oil , ubbelohde viscometer , viscosity , relative viscosity , temperature dependence of liquid viscosity , rheology , materials science , reduced viscosity , thermodynamics , mineral oil , wax , solvent , lubricant , chemistry , composite material , organic chemistry , metallurgy , scanning electron microscope , physics
Viscosity‐pressure‐temperature relations for paraffinic mineral base oils at pressures up to 0.7 GPa and temperatures between 30 and 90°C were determined using a falling‐ball‐type viscometer. The oils used were solvent refined oils, hydrocracked oils, and an oil produced by a wax isomerisation process. The viscosity at pressures higher than those possible with the viscometer was then derived by applying a simplified solution to the traction curves determined using an elastohydrodynamic disc‐on‐ball tester. When the measured viscosity and the calculated viscosity were plotted against pressure, for the oils with a viscosity index higher than 120 the viscosity derived from traction measurements followed the curve extrapolated to the high‐pressure region using either the Yasutomi or Roelands equations (the parameters for which were obtained using the viscometer). However, the calculated viscosity for the lower‐viscosity‐index oils deviated upwards from the extrapolated curve.