Colloidal processing, sintering and mechanical properties of zircon (ZrSiO4)

Dense Zircon ceramics were prepared from a commercial Zircon powder via the colloidal route, and critical processing variables were explored. To achieve highly dispersed suspensions, the zeta potential of Zircon was evaluated by adding different concentrations of a dispersant (ammonium polyacrylate). Zircon suspensions with high solid loading were slip cast in plaster molds and sintered at different temperatures. Final density was evaluated considering the amount of dispersant used in the original suspension. Crystalline phases were analyzed. Partial dissociation was observed in materials fired at 1600 and 1680 °C. Microstructure and mechanical properties, Vickers Hardness (Hv) and Fracture toughness (K1c), were evaluated and explained in terms of dispersant content, sinterization and partial dissociation. The achieved mechanical properties (Hv:8.5 GPa and K1c:1.7 and 2.7 MPa/m1/2) were also compared with the values obtained by other authors who used different processing routes.