Performance Of CuO/Al₂O₃Composite Nanoparticles As Lubricant Oil Additive

Al₂O₃nanoparticles were prepared by hydrothermal method and calcining method.Using the graft and situ surface modification method to change the surface of thenanoparticles. The optimum process parameters of hydrothermal method: aluminum source:aluminum isopropoxide, KH-560modifier dosage:1.0wt%, PH value:8, hydrothermaltemperature:220℃. In calcining method, the test factors are aluminum source:Al（NO3）3, PHvalue:9, calcining temperature:500℃, modifier dosage:1.5wt%. The structure of Al₂O₃nanoparticles was characterized by way of instruments analysis such as X-ray diffractionanalyzer, scanning electron microscope, laser particle size analyzer. The dispersion ability ofAl₂O₃prepared by hydrothermal method are better than calcining method. Al₂O₃aresuccessfully modified by KH560, which tested by Fourier transform infrared spectra （FT-IR）.CuO nanoparticles were prepared by hydrothermal method. The optimum processparameters: modifier: natrium oleinicum, hydrothermal temperature:150℃, hydrothermaltime:16h. CuO are succesfully modified by sodium oleate, testing through Fourier transforminfrared spectra （FT-IR）. After modified, the size of CuO nanoparticles changed from83nm to65nm and the dispersion ability improved, which are tested by laser particle size analyzer,scanning electron microscope and ZETA anylysis.CuO/Al₂O₃nanoparticles were prepared by hydrothermal method. The optimumprocess parameters: molar ratio of Al/Cu:1:1, hydrothermal temperature:140℃, modifier:oleic acid, modifier dosage:5.0wt%, PH:5. The CuO/Al₂O₃are composite nanoparticlescosnsist of CuO, Al₂O₃, CuAl2O4. The CuO/Al₂O₃are83nm with good dispersive abilityThe friction reducing and anti-wear behavior of the CuO, Al₂O₃and CuO/Al₂O₃nanoparticles used as additive in lubricant oil were analyzed by friction and wear test machineof MMU-10G. the friction coefficient of the samples studied have a biggest friction reductionof33.2%,23.8%,35.6%when0.05wt%of CuO,0.1wt%of Al₂O₃,0.1wt%of CuO/Al₂O₃composites were existed in the lubricant respectively. When0.05wt%of CuO,0.1wt%ofpure Al₂O₃and0.1wt%of CuO/Al₂O₃composites were existed in the lubricating oil, theWSD reduction were10.3%,36.2%,39.1%respectively. For further study, antifriction andantiwear performance of lubricant dispersed with CuO/Al₂O₃composites and physicalmixtures of CuO and Al₂O₃are also investigated. The lubricant dispersed with CuO/Al₂O₃composites has the best antifriction and antiwear effect by comparison to lubricant withCuONps, Al₂O₃Nps or physical mixtures of CuO and Al₂O₃, presenting the Synergistic effect of CuO and Al₂O₃. It seems that CuO/Al₂O₃composites has a trend to present Synergisticeffect, while physical mixtures exerting a adduct effect.Through the analysis of friction test, nanoparticles friction-reducing mechanism is asfollows: CuO/Al₂O₃composites transferred onto the thrust-ring surface together with thelubrication and a protective film was formed during the rubbing process. At the presence ofthe nanoparticles, friction between pairs was changed from sliding friction to rolling frictionwith the nanoparticles as bearings.