CASTOR OIL: A BIODEGRADABLE EXTREME PRESSURE AND ANTIWEAR LUBRICANT

Abstract

Castor oil, extracted from natural castor seed and mineral extreme pressure and antiwear lubricant, HD-90 gear oil were tested on a four ball machine. The test modes include: load, temperature, wear and seizure tests in sixty (60) seconds duration. The assessment criteria are: friction transients, surface temperature, flash temperature, wear scar diameter, and load capacity.

The results showed that natural castor oil apart from being biodegradable possessed extreme pressure and antiwear properties superior to one mineral gear oil HD 90 (A), though inferior to HD 90 (B). Also, the results suggests that the lubricant film in castor oil consisted of jelly brush-like polar molecules of fatty-acid (mainly recinoleic acid) oriented vertically to the surface - giving rise to static friction values which decreased with increasing load unlike the mineral gear oil, In the latter, lubricity is derived from the extreme pressure and antiwear additives in the mineral oil adhering to and/or reacting with the surface to form a protective laminar independent of the load, except transition is attained.