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.