Investigating the Contact Behaviour of Steel/Steel with Fatty Acid: An Experimental Applied Mechanics

Friction and wear modification abilities of fatty acids (Avocado seed oil) were investigated in comparison with a mineral oil (SAE10W30). It is evident that the mineral oil is non-biodegradable, and poses serious concern to the environment. Hence, its replacement with a biodegradable substance such as fatty acid obtained from avocado seed cannot be over emphasized. This study characterized the comparative advantage of the long chain saturated fatty acid over the mineral oil SAE10W30 using a ball-on-disc machine. A gas chromatography-mass spectrometry (GC-MS) approach was utilized to assess the free fatty acid content of the samples, while a Stribeck curve was employed to evaluate the lubrication regime of the samples. Avocado seed oil's principal fatty acid composition is up to 98% saturated, which may be the cause of the fatty acid's exceptional extreme pressure behaviour. The average friction coefficient (COF) of fatty acid was about 0.12 at moderate loading condition; while that of mineral oil was around 0.07. The average wear rate of fatty acid under moderate condition was 0.075mm3/Nm; whereas the mineral oil was on the average 0.068 mm3/Nm. A dramatic reduction in friction response occurred in these oil samples under extreme conditions, with the fatty acid proving superiority over the mineral oil. The fatty acid modified friction from 0.12 to 0.06, and wear rate from 0.075mm3/Nm to 0.06; while the mineral oil modified friction from 0.09 to 0.07, and wear rate increased from 0.068 mm3/Nm to 0.1 mm3/Nm. This affirms that the long chain saturated fatty acid extracted from avocado seed oil is a potential extreme pressure lubricant for various engineering applications.