Shear-thickening performance of suspensions of mixed ceria and silica nanoparticles

In this work, the shear-thickening (ST) performance of a novel suspension of ceria and silica mixed nanoparticles was systematically studied. Ceria/silica-shear-thickening fluids (CeO₂/SiO₂-STFs) of different concentrations were prepared by using an ultrasonication and mechanical stirring technique. The presence of ceria nanoparticles and their interaction with the SiO₂ nanoparticles in the STF were analyzed using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffractometry. Steady-shear rheological tests showed that distinct rheological behaviors and clear ST effects existed in CeO₂/SiO₂-STFs with different mass ratios. The viscosity increased from 50.97 (SiO₂-STF) to 111.51 Pa·s (CeO₂/SiO₂-STF), and the critical shear rate decreased from 63.09 to 19.95 s⁻¹ when the concentration of the ceria nanoparticles was 12 wt%. An oscillatory dynamic rheological analysis showed that the 12%CeO₂/20%SiO₂-STF suspension not only had significant energy storage and energy dissipation capacities but also presented excellent elastic behaviors when subjected to low stress and significant energy dissipation under high stress. The results also showed that the temperature exerted little influence on the viscosity of the CeO₂/SiO₂-STF suspension but had a significant influence on the ST effect. Furthermore, the current carried by the CeO₂/SiO₂-STF suspension increased with the increasing ceria nanoparticle content, indicating improved conductivity. This work provides a novel method for the production of high-performance STFs.