Study On The Preparation And Tribological Properties Of NbX₂ (X=S, Se) Nanolubricants

Adding additives into oil reduce friction and wear and even to mend the worn surface has been widely applied in lubrication engineering for quite a long time.But,the research and development of more effective additives have never been ceased since all kinds of additives mentioned above are still not perfect,especially their effect of the wear repairing is far from satisfactory.With the aid of nano-materials,a lot of novel work has been done with enormous encouraging achievements obtained because the tribological properties have been anhanced obviously.So transitional metal dichalcogenides were prepared as nanostructures(such as tubes,wires and particles),the unique closed nanostructure(nanotubes, nanowires,nanobundles) formed with rolled up materials have eliminated the fringe dangling bonds,thereafter they improve the chemical stability. Applied in lubricating oil,one sides,the nano-materials act as spacer between the two friction surface,and some ever proposed that the nano-materials were rolling like a ball in the grinding area which leads to the reduction of friction coefficient.Another sides,nano-materials deposit on the friction surfce and compensate the loss of mass,the so-called mending effect.In this article,experimental investigation and theoretical analysis were carried out on the preparation process and tribological properties of transitional metal dichalcogenides and diselenium NbX₂(X=S,Se) nanostructures.Firstly,The solid-phase reaction was used to produce NbS₂ nanotubes(nanowires),in evacuated and sealed quartz ampoules by mixed S and Nb powder.The component and microstructure of NbS₂ were investigated by means of X-ray diffraction(XRD),scanning electronic microscope(SEM) and transmission electronic microscope(TEM).Secondly,NbSe₂ nanofibers were obtained by heating sealed quartz ampoules by mixed Se and Nb in high temperature boxed furnace.Besides, the mixture of Se and Nb powders were milling in high energy ball-milling machine,the mixture after milling were heat in tubular furnace,a lot of NbSe₂ nanoparticles produced in mixture of Ar and N₂.The component and microstructure of NbSe₂ were investigated by means of X-ray diffraction (XRD),scanning electronic microscope(SEM) and transmission electronic microscope(TEM).Thirdly,for example NbSe₂,the growth and conditions of nanowires (nanofibers) and were discussed including reactional temperature,keep temperature time,coefficient of exceeding Se and so on,and the growth mechanism of NbSe₂ nanostructures were discussed in simply.Fourthly,The tribological properties of NbS₂ and NbSe₂ nanowires, acting as additives,were investigated in UMT-2 machine.Besides,NbSe₂ nanoparticles were added in basic oil,the tribological properties of them were UMT-2 test in different conditions.Then the tribological behavior of them were discussed and the tribological properties of different shapes NbSe₂ were compared.At last,the friction mechanism of lubrication including NbX₂ as additives was discussed preliminary.The lubrication has excellent tribological proerties in high load may be due to the following factors:one dimensional nanomaterial has unique closed structures,lubrication films and fill up-repair mechanism.