Rheological response of shear thickening fluid reinforced with silicon nitride nanoparticles

In this study, we studied the shear thickening performance of a novel silicon nitride and silica-mixed nanoparticles suspension. Silicon-nitride/silica-shear thickening fluids (Si₃N₄/SiO₂-STFs) with different mass fraction ratios were prepared using polyethylene glycol as a dispersion medium. For the Si₃N₄/SiO₂-STFs, the results showed that the viscosity increased from 168.35 (0.0 wt% Si₃N₄) to 1387.73 Pa s (7.5 wt% Si₃N₄), and a concomitant decrease in the critical shear rate from 10.0 to 3.55 s^–1, while thickening period decreased from 60.92 to 16.03 s^–1. Dynamic rheological analysis showed that compared with SiO₂-based STF (SiO₂-STF), the peak values of storage and loss modulus of 7.5%Si₃N₄/20%SiO₂-STF (7.5 wt% Si₃N₄ and 20 wt% SiO₂) increased nearly six times and three times, respectively. The results also showed that, compared with SiO₂-STF, the thickening ratio of 7.5%Si₃N₄/20%SiO₂-STF increases by 174% at 45°C and slows down the effect of temperature increase on the thickening period. This work provides a novel method for high-performance STF.