Tribological of Eu-doped WO3 coated with SiO2 transfer film formation on sliding surface

Europium nitrate, ammonium tungstate and hexadecyl trimethyl ammonium bromide were used, and Eu-doped WO3 (WO3:Eu3+) nanopowder was synthesized by the micro-emulsion method. Tetraethyl silicate was hydrolysed into SiO2 and WO3:Eu3+ nanopowder coated with SiO2 (SiO2/WO3:Eu3+) was obtained. The microstructure and morphology of the prepared nano-SiO2/WO3:Eu3+ powders were characterized by XRD, SEM, TEM and HRTEM. Results showed that the prepared nano-SiO2/WO3:Eu3+ powders composed of WO3 of monoclinic and SiO2 of amorphous, which was spherical and granular, and the grain size reaches 50 nm. The tribological behaviour of nano-SiO2/WO3:Eu3+ as extreme pressure and anti-wear additive in the water-based fluid was studied by a four-ball machine. The results demonstrate that nano-SiO2/WO3:Eu3+ exhibits superior load-bearing capacity, anti-wear and anti-friction performance in water-based fluid, especially when the optimal concentration of nano-SiO2/WO3:Eu3+ is 0.4 wt-%. WSD, COF and wear volume of the nano-SiO2/WO3:Eu3+ decreased by 62.43%, 30.20% and 67.34%, respectively, compared with that of the water-based fluid.