A Study on the Tribological Properties of Modified Biochar as Poly Alpha Olefin Additives
The nano-biochar materials were obtained by ball milling and alkali modification of cotton straw powder py-rolyzed at different temperatures,and were characterized by Raman spectroscopy,Fourier infrared spectroscopy,and X-ray photoelectron spectroscopy(XPS).Nano-biochar lubricants were prepared by incorporating nano-biochar powder into poly(α-olefin-6)(PAO6),the dispersion stability was characterized by particle size analysis and natural sedimentation ob-servation,and the wettability and tribological properties were tested.The results show that the number of oxygen-containing functional groups in biochar is increased by modification treatment,thereby enhancing the wettability of nano lubricant.The nano lubricant with 0.2％mass fraction of biochar treated at 700 ℃ has the best performance,and the friction coefficient decreases by 21.2％and the wear amount decreases by 43.0％compared with PAO6.Based on the physicochemical prop-erties of nano-biochar(NBC)lubricating oil and coupled with XPS analysis and morphological analysis of worn surfaces,the improvement of the frictional characteristics of PAO6 attributes to NBC can be ascribed to several factors.NBC,being a sheet-like material akin to a two-dimensional substance,comprising also of some minute particulate matter,concurrently exhibits the shear effects of interlayer materials and the filling and repair effects of particulate materials.Additionally,the incorporation of NBC can enhance the wetting properties,thereby improving the frictional characteristics of local micro-cracks,and facilitate the formation of friction films containing Fe3O4.
modified biocharpoly α-olefinfriction and wearfriction mechanism
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