Tribological behavior and tribofilm composition in lubricated systems containing surface-capped molybdenum sulfide nanoparticles

Abstract

The tribological behavior of surface-capped MoS 3 nanoparticles (nano-MoS 3 ) in hydrocarbon oils was studied both alone and in combination with ZDDP. It was found that the nano-MoS 3 additive alone demonstrates pro-wear properties and decreases the friction coefficient only at high temperatures. The combination with ZDDP demonstrates synergism in antiwear and antifriction activity even at low ZDDP content. X-ray Absorption Near Edge Structure (XANES) spectroscopy at the sulfur, molybdenum and phosphorus edges was used to identify the chemical species in tribochemical films. It was established that the nano-MoS 3 -formed tribofilms are composed of oxidized sulfur and molybdenum species while tribofilms formed by combination with ZDDP are composed of phosphate layers incorporating MoS 2 -type fragments providing friction reduction.

Influence of temperature and ZDDP concentration on tribochemistry of surface-capped molybdenum sulfide nanoparticles studied by XANES spectroscopy

“…We have previously reported the tribological properties and tribochemistry data based on XANES spectroscopy measurements for the compositions comprising surface-capped MoS 3 nanoparticles (nano-MoS 3 ) alone and in combination with ZDDP at 100°C [2]. We report here the results of further experiments on the nano-MoS 3 + ZDDP combination within the temperatures range of 100-160°C and at different ZDDP concentrations.…”

“…The XANES spectra were recorded in both the surface sensitive total electron yield (TEY) and the bulk sensitive fluorescence yield (FY) modes. The assignment of the fine structure in XANES spectra was obtained by using the spectra of model compounds, obtained by the authors or previously published data [2,7,8].…”

Tribological Properties of the Lubricant Containing Titanium Dioxide Nanoparticles as an Additive

“…The use of nanoparticles as oil additives and lubricants is a recent idea. Numerous nanoparticles have been investigated in recent years [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. These oil additives contain small particles of solid material, and their use is not straightforward and only recently has been recognized as feasible.…”

Viscosity and Tribology of Copper Oxide Nanofluids

“…Numerous nanoparticles used as oil additives have been investigated in recent years [2][3][4][5][6][7]. Results show that they deposit on the rubbing surface and improve the tribological properties of the base oil, displaying good friction and wear reduction characteristics even at concentrations below 2%wt.…”