Abstract:With 5W-30 lubricant as base oil and Al2O3/TiO2 as mixed nano additive,nano lubricating oil was prepared by adding 2% mass fraction of Al2O3/TiO2 in the lubricant.The influence of Al2O3/TiO2 nano additive on the tribological properties of the lubricant was study by using the tribological performance rig test to simulate the actual working process of cylinderpiston ring assembly.The surface wear condition was analyzed by using the field emission scanning electron microscopy (FESEM) to observe the morphology of piston ring sample.The influence of Al2O3/TiO2 nano additive on engine performance during the actual work process was studied by the engine bench test.The results show that the nano additive of Al2O3/TiO2 improves the friction and wear of cylinderpiston ring,and thefriction coefficient and the wear rate of piston ring is decreased significantly.The maximum decrease of friction coefficient is 50.6% and the average decrease is 42%,the maximum decrease of piston ring wear rate is 34.8% and the average decrease is 272%.The morphology of piston ring surface is improved and the worn surface is repaired and the scratches are significantly reduced.When the speed is 4 400 r/min,with the increasing of load,the output power of the engine bench test is up to 24.2%.The power in low load is increased significantly and the power in high load range is increased by 3.3%,the power performance is greatly improved.