Electric Field-assisted Synthesis Of ZnO Nanoparticles In Precipitation And Application Of Lubricate Addictives

In recent years, with the rapid development of nanotechnology research, the applicationof nanometer materials in lubricating oil field is greatly promoted. And the research showsthat if nano-particles are added into lubricating oil, the tribological performance of lubricatingoil can be effectively improved. As lubricating additives, nanometer particles have uniquephysicochemical properties and possess excellent tribological characteristics. Thecharacteristics of the nanometer materials（i.e. small size, large surface area, etc.）make iteasy to adsorb on the surface of friction pairs, fill the surface scratches and craters, and form alow shear stress layer on the friction surfaces, which reduce the friction factor, and make ithave the excellent effect of lubrication and self-healing. Because of the unique performanceof the nanoparticles, great progress has been made in the improvement of lubrication.Therefore, it has great significance to research and develop high-performance nanometerlubricating additives with good tribological property.In this paper, the nanometer ZnO particles with different morphologies （i.e., rodlike（thick）、rod like（thin） and flake like） were synthesized in a designed precipitationsynthesis device with electric field assistance, which utilized NaOH, Na₂CO₃, Zn（AC）₂andZn（NO₃）₂as raw materials. The synthesis was carried out at various reactant concentrationsand electric field intensity. The phase, morphology and microstructure of the as-synthesizedZnO particles were characterized by X-ray diffraction （XRD）、scanning electron microscopy（SEM） and fourier transform infrared spectrometer （FTIR）. The resuluts show that themorphologies of the as-synthesized ZnO particles were rod like and flake like. The electricfield could not affect the lattice shape of the product, but could affect the morphology of thecrystalline grain.The nano-particles with different morphologies have different tribological characteristics.The morphology of nano-ZnO particles has important impact on the relative properties andapplications. The stable complex lubricant oils were prepared by dispersing differentmorphologies ZnO nano-particles into20#oil, which were surface modified by differentsurface modification addatives. The tribological properties of ZnO nano-particles, whichutilized as a lubrication additive, were investigated by a four-ball friction testing machine, andthe friction coefficient and wear mass loss were discussed. The influence of the ZnOnano-particles on the basis oil, the ZnO nano-particles phase change during the lubricatingprocesses, the tribological chemical reaction on the friction pair surfaces, the lubrication mechanism of the ZnO nano-particles and actual simulation utilization performance, werealso discussed. The influence of the flaky ZnO nano-particles to the base oil （20#engine oil）and effect to the friction pair surfaces were systematically analyzed by FTIR, Ramanspectroscopy, XPS, SEM, etc. The results show that the ZnO nano-particles utilized as alubricating oil additive had excellent anti-wear and anti-friction properties, the optimal addingquantity was0.5wt%, and the ZnO nano-particles with flaky morphology had betterantifriction and self-repair effect.