Abstract:Silica nanospheres were prepared in polyether oil with the insitu solgel method.Effects of the ammonia concentration,water amount,tetraethyl orthosilicate (TEOS) concentration,polyether oil loading and reaction temperature on the size and morphology of SiO2 nanoparticles were investigated by transmission electron microscopy (TEM).The formation mechanism of the resultant SiO2 particles under different reaction conditions was discussed.An experimental study on friction reducing and wearresistance performances of nanosilica lubricating fluid with different nanoparticle concentration and size were carried out by utilizing fourball friction and wear testing machine.The results show that the friction coefficient and wear scar diameter of the nanosilica lubricating fluid is firstly decreased then increased with the increasing of nanoparticle concentration,and at the optimum concentration of nanoparticles,the effect of friction reducing and wearresistance is enhanced as the nanoparticles diameter decreases.The lubricating fluid shows better friction reducing and antiwear performance,however,due to the size variation,the optimum concentration did not show irregularity change.