Effect of dispersant and binder on the morphology of zirconia granules during spray drying

Polyacrylic acid (PAA) was utilized as a dispersant, while either copolymer of polyacrylic acid or polyvinyl alcohol (PVA) served as a binder for the preparation of zirconia granules using spray drying technology. Dense spherical granules were successfully obtained by employing 0.5 wt% Dispersant 1000 and 2 wt% PVA. Meanwhile, porous spherical granules were achieved when utilizing 1.5 wt% Dispersant 1,250,000 and 1 wt% PVA. Higher molecular weight dispersant necessitates larger mass for optimal addition. Compared to polyacrylic acid copolymer, PVA significantly improves the slurry viscosity and reduces the settling speed. A hypothesis is proposed that a three-dimensional network is formed by hydrogen bonding between PAA and PVA in the slurry, wherein zirconia particles and organic additives are uniformly immobilized, thereby facilitating the formation of spherical granules. By adjusting the molecular weight of PAA, enabling manipulation of dried granules morphology to achieve either dense or porous spherical granules.