Rheology, structure, and sintering of zirconia suspensions with pyrogallol-poly(ethylene glycol) as polymeric surfactant

摘要

Yttria-stabilized zirconia (YSZ) nanoparticles have been dispersed in water with pyrogallol-poly(ethylene glycol) polymer (i.e., Gallol-PEG) as surfactant. Fluid YSZ suspensions with an apparent viscosity < 10~2 Pas at a shear rate of 10~2 s~(-1) have been prepared with a solids concentration of 45 vol.% for the 90-nm YSZ nanoparticles. Theoretical calculation of interparticle potentials indicates that the adsorbed polymer renders steric hindrance critical to the suspension stabilization. The concentrated YSZ suspensions exhibit shear-thinning flow over a broad shear-rate range, resulted from the weak attractive minimum (~2.7 k_BT) found between the neighbouring particles in close proximity. The Gallol-PEG concentration influences not only the suspension rheology but also the particle-packing structure and sintered density of the slip-casted YSZ compacts. The YSZ suspensions with an optimal Gallol-PEG concentration of 2wt.% exhibit a low pore volume in the green state, facilitating hence densification (> 99% theoretical) upon subjected to sintering.