The friction and wear tests on AISI 1040 are carried out under raw, modified versions of two nonedible vegetable oils Pongam (Pongamia pinnata) and Jatropha (Jatropha curcas) and also commercially available mineral oil using a pin-on-disc tribometer for various sliding distances and loads. A significant drop in friction and wear for AISI 1040 is observed under Pongam and Jatropha raw oil compared to mineral oil, for the complete tested sliding distance and load, increasing the potential of vegetable oil for tribological applications. Stribeck curves are also drawn to understand the regimes of lubrication. Both the vegetable oils showed a clear reduction in the boundary lubrication regimes, leading to an early start of full film lubrication. 1. Introduction Escalating prices, rapid depletion of fossil reserves as well as the stringent legislations enforced by the International authorities have enlarged the scope around the globe to explore alternative ecofriendly lubricants [1, 2]. Oils of plant origin are promising, renewable, environmental the friendly, and nontoxic fluids, pose no work place health hazards and are readily biodegradable. Vegetable oils exhibit, number of performance blessings such as natural high viscosity (30 to 80% higher than mineral oil) and excellent lubricity due to their ester functionality. These are over 95% bio degradable and thus degrade much faster than mineral oils (20 to 30%), thereby offering greater potential when it comes to reducing the cost of disposal . Another important property of vegetable oils is their highflash points; for instance the flash point of Soybean oil is 326°C while mineral oils have approximately 200°C, thus reducing emissions and work place pollution. Further, biobased lubricants help to provide energy security for countries who use them and create local and regional economic development opportunities. Vegetable-based oils are finding their applications in various sectors of industry. For instance, the automotive lubricants derived from rapeseed, soy, and sunflower oils are finding good markets in European countries . Also, some of the vegetable oilbased lubricants and greases are finding their opportunities in specific applications like metal forming and working, food processing industry, machine elements, marine, locomotives, and so forth [5, 6]. Even though, the vegetablebased oils are finding their scope in various types of applications, it is meaningful to select oil for a particular application only after ascertaining the properties and behaviour. Otherwise, oil can also be selected
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