Study On Caco₃ Nanoparticles As Anti-wear And Friction-reducing Additives In Lubricating Oil

With the development of machinery manufacturing industry, the demand for lubricants and additives has increased year by year, and the performance of lubricant requirement is also getting higher and higher. In recent years, the emergence of nano-materials has provided a new choice for the development of lubricant additives. The method adopted is mainly integrating theory with experiment in the study. Relevant information received to achieve the desired objective of the study through the chemical analysis experiment. We research on tribological properties of nanoparticles as lubricant additives by the electron microscope analytical as well as friction performance test.Firstly, after the surface of nano-CaCO3 modified with aluminum coupling agent by wet-modification, which improves the dispersion stability of nanoparticles in lubricants, aluminum coupling agent dosage of 2.5% is the best through activation grade and oil-absorbed value. Then the modifier amount can be regarded as the best dosage that is confirmed by settling volume in liquid paraffin, and the superficial modified mechanism is analyzed.Secondly, being allocated proportion according to the mass fraction and partly, the modified nano-CaCO3 and nano-zinc have been added to the liquid paraffin. PB value, which means the biggest burthen when metal has not to be locked and occluded, and rubs spot diameter D value used as the main evaluate index. They are measured through the four-ball friction tester under certain load function. Lubricating oil's friction performance has been determined through the frictional wear tester testing the friction coefficientμ. The test result indicates that: after a small amount of nanoparticles added to the base oil, lubricant property of anti-wear and friction-reducing has the enhancement. Moreover, it is better when nanoparticles joining by the mixture way than by alone. The best combination granule of nano-CaCO3 and nano-Zn is 1:1, the total concentration is 0.6%.Thirdly, when lubricants samples which contain additives of different allocated proportion carried out stability test and anti-rust performance test, the stability is good and its performance against rust is qualified. When nanoparticles that nano-CaCO3 and nano-Zn is 1:1 and total concentration is 0.6% added into 460 gear oil, gear efficiency of adding nanoparticles lubricants has about 1% enhancement. Finally, the mechanism of lubricant property of anti-wear and friction-reducing is also studied by SEM that is scanning electron microscope and TEM that is transmission electron microscope. In the course of rubbing, nano-particles of calcium carbonate can form protective film which includes the calcium carbonate and the calcium oxide which become by its decomposition, which show better tribological properties. Nano-zinc and solid surface combine to form a smooth layer of protection, at the same time the nanoparticles pad microscratches, thus reduces friction and wear significantly. In brief, lubricant has good tribological property because of nanoparticles combination serving as additives.