Investigation On Tribological Properties Of Modified Carbon Nanoparticles As Aviation Lubricant Additives

With the development of aviation industry technology and people’s attention to environmental protection,higher requirements are put forward for the performance and environmental friendliness of aviation lubricants.Mineral oil cannot meet the needs of industrial production due to its poor biodegradability and weak film-forming ability.Synthetic base oil,especially poly α olefins and neopentyl polyol esters,has become the most widely used aviation lubricating base oil.However,domestic synthetic base oils cannot meet the performance requirements of high-grade lubricants for base oils.Efficient lubricating additives are the key to improve the lubricating performance of base oils.Carbon nanoparticles(CNPs)have been the research hotspots of carbon-based nanomaterials in recent years.Due to its stable chemical properties,green environmental protection,good self-lubricating and self-healing properties,it has great potential in the field of efficient and environmentally friendly lubricating additives.However,due to the poor compatibility between CNPs and base oil,the research on CNPs as lubricating additive is still in its infancy,and the research on CNPs as aviation lubricating additive is rarely reported.Based on this,oil amine modified carbon nanoparticles(CNPs-OA)were prepared by one-step pyrolysis method and characterized.The tribological properties of CNPs-OA in three different aviation lubricating base oils were systematically investigated by using UMT and four-ball friction and wear tester,and the lubrication mechanism was finally discussed.The specific research results are as follows :(1)Oilamine modified carbon nanoparticles(CNPs-OA)were prepared by one-step pyrolysis using CA as carbon source,OA as modification reagent and reaction medium.The characterization results showed that OA molecules were covalently grafted on the surface of CNPs through amide bond.CNPs-OA is mainly amorphous with particle size of 15-20 nm.CNPs-OA was stably dispersed in PAO3,PAO20 and NEP2 base oils in the form of 3-5 small polymers;CNPs-OA has good thermal stability.Characterization results It shows that OA molecules are successfully covalently grafted on the surface of CNPs through amide bonds;CNPs-OA is mainly amorphous carbon with a particle size between 15-20nm;CNPs-OA is stably dispersed in the form of 3-5 small polymers among PAO3,PAO20 and NEP2 base oils;CNPs-OA has good thermal stability.(2)UMT friction test(load 40N)results: CNPs-OA can improve the lubrication performance of the three aviation lubrication base oils to varying degrees.CNPs-OA shows good dispersion stability in PAO3,PAO20 and NEP2;under 40 N load,when the additive concentration is 0.5wt%,1.5wt% and 0.5wt%,the average friction coefficients of PAO20,PAO3 and NEP2 base oils decreased by 7.1%,32.8%,and 11.4%,respectively,and the average wear volumes decreased by 28.6%,29.4%,and 39.0%,respectively.Moreover,the long-time experimental results illustrated that CNPs-OA possessed a long service life.Based on the analysis of the wear scar surface,the lubrication mechanism of CNPs was discussed.Its excellent tribological properties may be derived from the film lubrication effect of the OA group and the nano-lubrication effect of the carbon core.(3)Four-ball friction test(load 392N)results: when the addition concentration was 1.0wt%,the average wear spot diameter of PAO20 decreased by 29 %;When the addition concentration was 0.3 wt %,the average wear scar diameter of PAO3 decreased by 28.9 % at the maximum.When the addition concentration was 1.5 wt %,the average wear scar diameter of NEP2 decreased by 10.2 %.