Pressureless sintering of gelcast ZTA–MgO–TiO2 systems as potential dental ceramics

Abstract

The pressureless sintering behaviour of gelcast zirconia toughened alumina (ZTA) containing the total 5 wt-% additives of MgO and TiO2 was investigated. The effects of four combinations of MgO and TiO2 on the bulk properties, morphology and phase composition of the ZTA composites were evaluated in comparison with pure ZTA in the temperature range of 1150–1600°C. Four combinations of MgO and TiO2 initiated effective densification and enhancement at 1450°C, as indicated by the relative density and three-point bending strength measurements and fracture morphological observations by using scanning electron microscopy. X-ray diffraction analyses confirmed that the difference in the bending strength among four groups of ZTA composites was due to the MgO dependent formation of minor MgAl2O4 and TiO2 induced polymorphic transformation of tetragonal phase to monoclinic ZrO2. These results are useful to further develop dental ceramics, including glass infiltrated ZTA.