| Automobile exhaust pollution is becoming more and more serious.This study aims to protect the environment from two aspects of energy saving and emission reduction.The addition of graphene as an additive can improve the antiwear and load capacity of lubricating oil.However,there are two main problems to be solved when graphene is used as lubricating oil additive: the strong π-π bond between graphene sheets makes it easy to agglomerate and separate,and the dispersity of graphene in lubricating oil has been the key factor to restrict the further development of graphene lubricating oil.In this study,the organic molybdenum lubricant is compounded with graphene.The molecular force of the organic molybdenum lubricant can make it adhere to the surface of graphene and improve the dispersion of graphene.Secondly,the production of oxide is still an important factor affecting the use effect of graphene.The new oxide can quickly combine with graphene with high specific surface energy,and then be filtered out by the filter in the lubrication system after oxidation condensation,resulting in the loss of graphene efficiency in the oil.Therefore,effective control of oil oxidation is the key to ensure the application effect of graphene.In this study,the use life of graphene can be effectively extended by introducing appropriate antioxidant without affecting the antiwear ability of graphene.The main research contents of this project are as follows:(1)Four ball friction test was used to select different volume fractions of graphene for test,to explore the anti-wear performance of graphene single component;to select different volume fractions of molybdenum carbamate for test,to explore the anti-wear performance of molybdenum carbamate single component;to composite graphene molybdenum carbamate,to investigate its composite effect.Adjust the proportion of graphene mother liquor and molybdenum carbamate to choose the best proportion.(2)Through the bench test,the antioxidant components of the compound lubricating oil of-diisooctyldiphenylamine(DODPA)and molybdenum carbamate were studied.The results show that there is a good synergistic effect between thiadiazole derivative and DODPA.When the content of thiadiazole derivative is 0.05%,the comprehensive practicability and economy are determined.The final ratio is 0.05% DODPA.Molybdenum carbamate,an antiwear agent,has no "antagonistic effect" with antioxidant.The comprehensive oil consumption can be reduced by 0.53%.(3)The results of the rotary oxygen bomb test show that with the increase of the content of complex antioxidant in the lubricating oil,the time required for the test also increases significantly.It means that the compound antioxidant can prolong the oxidation induction period of lubricating oil,and the antioxidant can effectively inhibit the oxidation decay of lubricating oil.(4)The results of sediment bench test showed that with the increase of DODPA content,the combustion chamber sediment also decreased.However,the effect of sediment on intake valve is not very obvious,so it is suggested to restrain carbon deposition from the aspect of fuel.Through the analysis of emission spectrum elements and direct reading ferrography,the results show that the total wear level increases steadily with the increase of test time,and the content trend of metal elements also shows a steady increase.No rapid increase of abnormal wear elements is found,and the running state of friction pairs is normal.(5)The experimental results show that the CO and hydrocarbon emissions are decreased after the addition of graphene lubricating oil complex antioxidant.The compound lubricant antioxidant has remarkable effect on reducing carbon emission.The double idle test shows that with the addition of additives,the carbon emission of gasoline engine exhaust gas can be controlled to a certain extent,and the emission of hydrocarbons in idle and high idle state is reduced by 29.79% and 29.39%,respectively.The CO emission decreased by 17.24% and 16% respectively. |
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