Preparation Of Tin Disulfide Nanosheets And Research On Its Tribological Properties As Lubricating Oil Additives

With the gradual maturity and application of nanotechnology,the development of efficient nano-lubricating additives has become an important research direction in the field of tribology.Among them,two-dimensional metallic sulfides have attracted extensive attention of researchers because of their specific nanoplate-like structures.In this paper,the hydrothermal synthesis method with deionized water as the solvent was used to successfully prepare SnS₂ nanosheets,and its surface structure was characterized by scanning electron microscopy.Its chemical composition was analyzed by means of Raman spectroscopy,EDS,XPS,etc,and the dispersion of SnS₂nanosheets in PAO base oil as lubrication additive was investigated.The influences of sliding speed,load and additive concentration on the tribological properties of base oil after adding SnS₂ nanosheets were reaserched.The lubrication mechanism of SnS₂nanosheets as lubricant additive was analyzed by EDS and XPS spectra.At the same time,the tribological properties of ZDDP and SnS₂ nanosheets when used in combination were studied,and the tribological mechanism of the synergistic friction reduction and antiwear effect of ZDDP and SnS₂ nanosheets was analyzed.The following results were obtained:（1）SnS₂ nanoparticles were successfully prepared by hydrothermal synthesis using stannous chloride dihydrate（SnC1₂·2H₂O）and thioacetamide（C₂H₅NS）as precursor compounds and deionized water as solvent.SnS₂ nanoparticles have a two-dimensional lamellar structure with a relative thickness of about 10 nm and a transverse size of about100 nm-200 nm.EDS and XPS characterization shows that SnS₂ nanoparticles only contain the Snelement and the S element.（2）SnS₂ nanosheets,as a lubricant additive of PAO base oil,can effectively enhance the tribological properties of base oil.Under 40 N loading and 1h duration,the stable friction coefficient of PAO oil containing 0.5 wt%SnS₂ nanoparticles is 0.11,while that of pure PAO oil is greater than 0.3.The corresponding wear capacity of PAO+SnS₂ mixed oil is 41.81×10^-3 mm³,and that of pure PAO oil is 275.70×10^-3 mm³.EDS analysis and XPS spectrum analysis show that the improvement of friction reduction and wear resistance of PAO oil containing SnS₂ nanoparticles can be attributed to the formation of effective tribological film,which is composed of SnS₂nanoparticles and their oxides,indicating that SnS₂ nanoparticles can be deposited in the sliding contact zone to form a lubricating film,which improves the tribological properties of base oil.（3）SnS₂ nanosheets and the commonly used antiwear additive ZDDP have obvious synergistic antifriction and antiwear properties,and the synergistic effect is enhanced with the increase of the concentration of SnS₂ nanosheets in base oil.For ZDDP containing 0.5wt%,the wear volume is 54.61×10^-3 mm³,after adding 0.125 wt%SnS₂,the wear volume is only 34.53×10^-3 mm³.However,after adding 1wt%SnS₂,the wear volume is only 17.59×10^-3 mm³.The XPS spectrogram analysis of the wear scar showed that during the sliding process,ZDDP,SnS₂ and the surface of the friction pair had tribochemical reactions to form a friction reaction film containing phosphate,sulfate and sulfide,which plays a lubrication role.