Abstract

The environmental pollution caused by mineral oil (petroleum based) lubricants coupled with the depletion of petroleum reserves have encouraged the sourcing of more biodegradable and environmental friendly lubricants. To this end, vegetable oils have been sponsored as suitable replacements to these petroleum based lubricants. This chiefly because of their biodegradable nature and plethora in the environment. One major limitation in the use of vegetable oils as lubricants is their seemingly poor performance when exposed to extreme temperature and pressure scenarios. This is due to the fact that they undergo oxidation at high temperature operations which causes an altering of its physical as well as chemical nature. Upon this degradation, the released oxygen bond becomes harmful to metals as it sponsors oxidation on the metals surface which tantamount in structural weakness evident in the near future as rusts. This paper tested the high temperature and pressure performance of vegetable oils using a fourball tribometer according to ASTM D2783. The lubricants used for this comparative testes were commercial hydraulic oil, RBD palm olein, palm fatty acid distillate, jatropha oil and commercial stamping oil. The end performance evaluation showed that jatroha oil, a vegetable based oil has higher coefficient of friction in comparison to the other oils which were mineral (petroleum based) oils. The study also exposed that the wear scars on the metal surface when machined with the vegetable oil is lower than that when the mineral oils were used. Hence the vegetable oils are very suitable for use as lubricants under extreme high temperature and pressure regimes.