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All mechanical systems require lubrication between interacting surfaces to avoid failure of
mechanical components and to decrease the losses due to friction, especially for the interacting
bodies that operate in boundary lubrication regimes. Due to the decrease in the reserve of mineral
oils, increasing environmental concerns, and difficulties in the disposal of non-biodegradable
conventional lubricants, a trend is increasing amongst researchers to produce more environmental
friendly lubricants. The use of bio-lubricants as an alternative to mineral based oil is limited due
to its low thermal stability. Ionic liquid are molten salts which are environment friendly and can
be used as additive to bio-lubricants to enhance its physiochemical properties. The effectiveness
of ionic liquid in bio-lubricants depends upon a lot of factor amongst which its miscibility with
that particular lubricant plays an important role. Ionic liquids make strong interaction with polar
lubricants and hence can be effectively used as additives to bio-lubricants. Among ionic liquids
phosphonium based ionic liquids are found to show best results with lubricants and hence is used
in this study.
In this thesis tribological performance of phosphonium-based ionic liquid Tri hexyl tetra decylphosphonium bis (2, 4, 4-trimethylpentyl) phosphonate when used as an additive to Cottonseed
oil, Rattan Jot oil, Waste Cooking oil and Polyalphaolefin (PAO) will be studied at different
operating conditions and results will be compared with conventional PAO base oil. The physical
properties of these oils were already investigated by a previous student Tehreem Naveed[1] and
their tribological analysis is done in this study. Tribological performance of all lubricants were
studied using a four ball tribometer and its wear scars were determined using an electronic
microscope OLYMPUS. From this study it was found that with the addition of ionic liquid,
tribological performance of all bio-lubricants enhanced. Ionic liquid does not have much effect on
the tribological performance of PAO. Rattan Jot oil was found to have the best tribological
properties with and without addition of ionic liquid into it.