posted on 2016-07-27, 00:00authored byHua Li, Anthony E. Somers, Mark W. Rutland, Patrick
C. Howlett, Rob Atkin
The lubrication of titania surfaces
using a series of ionic liquid
(IL)–hexadecane mixtures has been probed using nanoscale atomic
force microscopy (AFM) and macroscale ball-on-disk tribometer measurements.
The IL investigated is trihexyl(tetradecyl)phosphonium
bis(2,4,4-trimethylpentyl)phosphinate, which is miscible
with hexadecane in all proportions. At both length scales, the pure
IL is a much more effective lubricant than pure hexadecane. At low
loads, which are comparable to common industrial applications, the
pure IL reduces the friction by 80% compared to pure hexadecane; while
the IL–hexadecane mixtures lubricate the titania surface as
effectively as the pure IL and wear decreases with increasing IL concentration.
At high test loads the adsorbed ion boundary layer is displaced leading
to surface contact and high friction, and wear is pronounced for all
IL concentrations. Nonetheless, the IL performs better than a traditional
zinc–dialkyl–dithophosphate (ZDDP) antiwear additive
at the same concentration.