Lipophilic magnetite nanoparticles coated with stearic acid: A potential green and low cost way to improve thermal stability and tribological properties of fully formulated low viscosity engine oils

Lipophilic nanoparticles of magnetite (d approximate to 10 nm) functionalized with stearic acid (MagNP) were tested as additive in modern engine oil with low viscosity and high additization. Its thermal and tribological properties were evaluate using TG/DTA and a high frequency reciprocating tribometer, respectively. All tests were performed with the neat oil and the oil+MagNP. The analysis showed that MagNP: i) improved thermal stability of the engine oil; ii) kept friction values lower and more stable; iii) drastically reduce wear marks; iv) improved the deposition of additives from the lubricating oil onto the worn surface.