Effect of TiO₂ in Fine Zircon Sintering and Properties

Abstract

The effect of the TiO₂ addition in the ceramic processing of dense zircon materials from zircon fine powders was established. The addition of TiO₂ (5-10 wt%) permitted to obtain dense ceramics at lower temperatures (100-150 oC below), with comparable mechanical behavior. The thermochemical processes were described after a multi-technique experimental approach, which included a sintering analysis, powder X-Ray diffraction analysis (XRD), scanning electronic microscopy (SEM) and Vickers hardness of the polished dense obtained ceramics. After 1400 oC heating programs, the added TiO₂ acts as a sintering aid with no important chemical reactions, and presented improved mechanical behavior in comparison with pure zircon ceramics. On the other side, in samples fired at 1500 oC, TiO₂ partially (≈50 %) reacts with zircon, forming ZrTiO4, while the formed SiO₂ goes to the grain boundaries. Samples with 5 wt% TiO₂ present better mechanical behavior than the ones with 10 wt%. The performed mechanical characterization indicates the merits of the material processed by this inexpensive processing route. Developed density, hardness (≈10 GPa) and fracture toughness (≈2 MPa.m^-1/2) are comparable with the best figures reported.