Bio-Based Lubricant in the Presence of Additives : Classification to Tribological Behaviour

Mineral oils as lubricating oils are used in the automotive industry to reduce wear and frictional forces. However, the use of mineral oil is toxic to the environment, and reserves of mineral oils are depleting. Bio-based oils can serve as an alternative to mineral oils because of their biodegradability. In the aspect of biodegradability, vegetable oils give 100% biodegradability. On the other hand, mineral oils have 15–35% biodegradability. However, there are certain issues related to bio-based oils because of inferior cold flow characteristics, higher oxidation and the presence of hydrolytic stress. To improve the performance of bio-lubricants, some additives (nano-particles and micro-particles) of metals, metal oxides, etc. have been in use. Improvement in the extreme pressure properties, decrement in pour point, contamination prevention, corrosion prevention and reduction in oxidation was observed by the addition of these additives. This chapter focuses on physical and chemical properties of additivated lubricants, classification and applications of additivated bio-based lubricants in various sectors, lubricant additives and their types and tribological testing procedures and results.