Small size 3±0.5nm alumina (Al2O3) nanoparticles have been prepared using control
precipitation method in aqueous solution. Aluminum nitrate and ammonium carbonate
were added to heated distilled water. Aluminum hydroxide was formed and calcined at 550
oC to produce boehmite (ɤ-Al2O3) nanoparticles. The novelty of this work is the surface modification
of the formed ɤ-Al2O3 nanoparticles, characterized by their low cost, ease production,
high melting point, corrosion resistance, high strength, chemical stability, low thermal
conductivity and good electrical insulation properties by using oleic acid as a coupling agent
to avoid the disadvantage of using nanomaterials as additives to lubricant oils due to their agglomeration
to enhance the lubricant oil specifications. With three concentrations of surface
modified Al2O3 nanoparticles, an improvement for physical properties of lubricant oil was
observed. Lubricant with 0.05 wt% of surface modified Al2O3 nanoparticles has not applicable
change in viscosity and has notable improvement in flash point, pour point, thermal stability
and antiwear ability by rates 4.3%, 150%, 33% and 9.4%, respectively. Surface modification
process for alumina provides a suitable dispersion of nanoparticles inside lubricant oil.
In conclusion, alumina nanoadditives enhance the lubricant base-oil specification that introduces
a leap for lubricant industry.