Tribological of Eu-doped WO 3 coated with SiO 2 transfer film formation on sliding surface

Abstract

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.