Improvement of the lubrication performance of an ester base oil with coated ferrite additives for different material pairs

In the present work, lubrication properties (friction and wear) of a synthetic ester oil, tris(2-ethylhexyl) trimellitate (TOTM) containing ferrite nanoparticles coated with oleic acid (F3O4-OA) were investigated for two different material pairs: steel ball-steel disc silicon nitride disc. Thus, four TOTM nanolubricants formulated: + 0.010 wt% Fe3O4-OA, 0.015 0.020 Fe3O4-OA 0.025 showing all them moderate time stability due to coating. Wettability behaviour ferrite-based on surface was analysed, revealing that addition in decreases contact angle between lubricant surface. Friction sliding tests performed neat formulated under 20 N load. All showed lower coefficients friction than those reached base oil both pairs. Worn area significantly reduced concentrations steel-steel highest nitride-steel contact. Specifically, largest achieved reductions F3O4-OA nanolubricant: 43% reduction (silicon nitride-steel) 17% wear track width, 42% deep 36% (steel-steel). addition, roughness analysis Raman microscopy tested discs tribofilm formation repairing mechanisms occur.