Dense zircon (ZrSiO4) ceramics by a simple milling-sintering route

In this work, a simple milling sintering route (pressure less) to process dense zircon ceramics from fine (D50 0.8 µm) zircon powders is explored. Particularly, the milling time effect (0-120 min) and the maximum sintering temperature (1400-1600 °C) were studied. The sintering grade developed microstructure and Vickers hardness (Hv) were evaluated and correlated. The dissociation of silicate into (monoclinic and tetragonal) zirconia and silica was evaluated by X-ray diffraction followed by the Rietveld method; it was found to be below 10 wt% in all the studied ranges. The sintering was enhanced by the milling pretreatment. No sintering additives were incorporated. Dense zircon (porosity below 1 %) ceramics were obtained by a simple milling-sintering route of this high refractory powder at 100-200 °C below the sintering temperature used with conventional processing routes to obtain equivalent final properties. The Vickers hardness reached: 9.0 GPa.