| With the rapid development of modern industry,the performance of lubricating oil is getting more and more attention.The study of superior performance additives to improve the antifriction and antiwear properties of lubricant is the pursuit of the lubrication field and an important frontier subject.Using nano-particles as lubricating oil additives can protect the friction pairs and reduce the friction coefficient with excellent lubricating effect.Therefore,more and more attention has been paid to the research of lubricating oils with nano-materials as additives.The nano-serpentine particles are used as lubricating oil additives in this paper to study the effect of dispersion and stability on the performance of lubricating oils.In this paper,the nanometer serpentine particles obtained by ball milling are used as lubricating oil additives to prepare lubricating oil samples.The absorbance and centrifugation rate were measured by low-speed centrifuge and spectrophotometer;the friction coefficient and wear rate of 45/45 friction pair in lubricating oil were evaluated by MMU-5G screen friction and wear tester;then the effects of the concentration of nano-serpentine particles addition on its dispersion and stability in basic lubricating oils were studied systematically.On this basis,the effects of the type and the concentration of different surface modifiers(silane coupling agent KH550,oleic acid and compound modification KH550/ oleic acid)on dispersion,stability and tribological properties were carried out.The friction and wear surface morphology and tribological mechanism of metal friction pairs were analyzed by scanning electron microscopy(SEM)and energy spectrum(EDS).Research shows that with the increasing concentration of nano-serpentine particle,the absorbance value of unmodified nano-serpentine particles in the lubricating oil increases first and then decreases,and the centrifuge precipitation increases first and then increases.The friction coefficient decreased obviously compare with the base lubricating oil,and the comprehensive performance of lubricating oil is the best when the concentration of nano-serpentine particles is 2.5 wt.%.On basis of the above research,the nano-serpentine particles were modified by silane coupling agent KH550,oleic acid andcompound modification-KH550/ oleic acid.The results showed that use only KH550 can improve the dispersion of the modified nano-particles in lubricating oil but can't improve the suspension stability,and the modified lubricating oils has poor the tribological properties.The dispersion and stability of the nano-serpentine particles modified by oleic acid are significantly improved in the lubricating oil.The lubricating oils modified by oleic acid has good the tribological properties with small friction coefficient and wear rate,and the microscopic appearance of the wear surface is flat with few scratches and furrows.After the surface modification of nano-serpentine with KH550/ oleic acid complex modifier,the performance of lubricating oil has been greatly improved.When the amount of KH550/ oleic acid compound modifier is certain,the higher the ratio of oleic acid,the better the comprehensive performance of modified nano-serpentine particles in lubricating oil is.Adding nano-serpentine particles to the base lubricating oil can obviously improve the tribological properties of the base lubricating oil,and can reduce friction and wear and provide the self-repairing functions to the friction pairs. |
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