Yttria-stabilized tetragonal zirconia prepared using gel casting and two-stage sintering

ABSTRACT Gel casting technology and a two-stage sintering process were used to produce yttria-stabilized tetragonal zirconia (YTZP) ceramics with excellent mechanical properties. A carbonic acid-based polyelectrolyte dispersant was used as a dispersant to prepare a well-dispersed nano-sized (94 nm) zirconia slurry with a high solid content (45 vol%) for gel casting. The functional carboxyl groups of the polyelectrolyte dispersant reacted with epoxy monomer (ethylene glycol diglycidyl ether, EGDGE) as it was added to the slurry, resulting in a decrease in gelling incubation time and an increase in viscosity, resulting in gel casting failure. Adding hydroquinone (HQ) to the slurry can cause polymerization to be delayed and the gel-casting working time to be extended. To control grain growth, a two-stage sintering process was used. The temperature for the first stage of sintering was set at 1300°C, then lowered to 1240°C and soaked for 24 h in the second stage to achieve a relative density of greater than 99%. The two-stage sintered sample has a Vickers hardness of 15.2 GPa, fracture toughness of 7.8 MPa.m1/2, and flexural strength of 771 MPa.