Analysis On Crystal Formation And Physio-Tribological Properties Of Lithium Based Grease Developed From Coconut Oil (Cocos Nucifera)

Abstract

The increase in demand for alternative base oil for lubricant has led to the study of non-depleting source like vegetable oils. Some studies have reported the development of grease from sunflower oil and castor oil, which establish the probability of use of vegetable oil as potential base oil. In the present study, an eco-friendly NLGI grade 3 grease was developed using coconut oil as base oil and lithium stearate as thickener. The inherent tribological properties of the coconut oil and grease were evaluated. Tests results of newly formulated grease procured from cone penetration, rolling stability, water wash out, grease leakage, friction and wear are compared to a commercial sample of same grade. Even though the newly formulated grease is found to be competent to the commercial sample, the crystal formation at low temperature has restricted its applications at lower temperatures. Crystal formation at low temperature is due to the agglomeration of saturated fatty acids commonly known as wax occurred due to the low cold flow characteristics of the oil (pour point of coconut oil 26.55°C). The tribological results show that the performance of the newly formulated grease is comparable to commercial greases and its application is restricted to moderate climatic conditions.