Effective lubricant additive of nano-Ag/MWCNTs nanocomposite produced by supercritical CO 2 synthesis

摘要

AbstractSilver nanoparticles dotted on the external walls of multi-walled carbon nanotubes (MWCNTs) were prepared by an aldehyde reduction process in supercritical carbon dioxide (scCO2) fluid. The silver nanoparticles with narrow size distribution of 5–15?nm are uniformly anchored on MWCNT walls. The prepared nanocomposite of nano-Ag/MWCNTs was used as lubricant additive in 10w40 engine oil and its lubricating performances was evaluated by a four-ball tribometer. The friction coefficient and wear scar diameter were reduced by 36.4% and 32.4% respectively, when the engine oil was dispersed with 0.18?wt % nanocomposite. After synthetically analyzing worn surface by means of scanning electron microscopy and X-ray photoelectron spectroscopy, the lubrication mechanism of this nanocomposite as oil additive is discussed and postulated.Highlights?S-Ag/MWCNTs was fabricated by an aldehyde reduction in scCO2fluid.?Ethanol acted as solvent, cosolvent and reductant in the preparation process.?ScCO2fluid influenced the microstructure and lubricating performances.?The S-Ag/MWCNTs was more effective lubricant additive compared to nano-Ag and MWCNTs alone.?The S-Ag/MWCNTs formed deposition film and smoothed the mating interface.]]>