High‐pressure rheology of eight synthetic lubricants based on phase diagrams
作者:
Md. Ziaur Rahman,
Nobuyoshi Ohno,
期刊:
Journal of Synthetic Lubrication
(WILEY Available online 2004)
卷期:
Volume 20,
issue 4
页码: 317-330
ISSN:0265-6582
年代: 2004
DOI:10.1002/jsl.3000200405
出版商: John Wiley&Sons, Ltd
关键词: synthetic lubricant;rheology;free volume;phase diagram;density;viscosity
数据来源: WILEY
摘要:
AbstractNew sets of equations have been constructed from the density‐pressure‐temperature and viscosity‐pressure‐temperature relationships to determine the rheology of synthetic lubricants at high pressure. A phase diagram was first plotted for the oils up to a pressure of 1.2 GPa and temperatures from 303 to 353 K using high‐pressure density experimental results and others. For the oils at temperatures of 313, 333, and 353 K, the high‐pressure viscosity experiment was done up to a viscosity of 104Pa s and up to a pressure of 0.4 GPa. A relationship, based on free volume theory, between pressure and temperature with varying density and viscosity was proposed. It was found that the new equations from these relationships could predict the high‐pressure rheology more closely than those of previous researchers. Moreover, it was shown that the Ehrenfest equation or the gradient of the phase diagram is closely related to the expansion coefficient o
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