The Research On Nano-lubricating Materials And Their Surface Modifications

In the field of tribology, the application of traditional oil-based agent, additives for extremepressure and antiwear had been limited due to itself defects. The oil-based agent had a low loadbearing capacity, and extreme pressure and antiwear additive often contained the element ofsulphur, phosphorus, chlorine, which polluted surrounding environment, and had been restrictedto use overseas. Developing lubricating oil additive with good antiwear, high load-bearingcapacity and self-repair of wear surface was one of the important questions in tribology.The modifications and tribological properties of nanometer particles had been studied in thispaper. The surface of TiO₂ nanoparticles was modified with stearic acid with the reference ofmany relevant materials. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectronspectroscopy (XPS), TGA and DTA were used to characterize the morphologies and structures ofthese surface-modified nanoparticles. The tribological properties of these surface-modifiednanoparticles added as additives in lubricating oil were evaluated on a four-ball machine, and thereducing tribological factors of these surface-modified nanoparticles were analyzed.1. There was a stronger chemical bond between the carboxyl of stearic acid and TiO₂nanocores, which existed on the surface of TiO₂ nanoparticles by Chelating.2. The binding energy of Ti2p electron in the surface-modified TiO₂ nanoparticles was close tothat of bare TiO₂ (anatase). The binding energy was 458.4eV in low Ti2p^3/2 electron.3. With the temperature roused, no peak existed in profiles of TGA and no weight lost inprofiles of DTA after 446.2℃ . The weight of surface-modified TiO₂ nanoparticles lost below10%.4. The antiwear and load capability was increased while the friction coefficient was decreasedby adding surface-modified TiO₂ nanoparticles in lubricating oils. The PB was increased from370N to 590N and friction coefficient decreased from 0.112 to 0.098 with the additive was0.50% at the certain conditions.5. The performance of CA20 oils with surface-modified TiO₂ nanoparticles was improvedmuch better than CA20 oils in antiwear and load capability.6. The good tribology of surface-modified TiO₂ nanoparticles as lubricating additives mightresult from surface films between the frictional surfaces, which could improve thefriction-reducing and antiwear of oils.