Simultaneous effect of microwave sintering and TiO2 addition on sinterability, mechanical properties, and scratch resistance of zirconia toughened alumina ceramics

This paper delves into the transformative impact of varying titanium dioxide (TiO₂) content on the sinterability, physical, and mechanical properties, as well as scratch behavior, of zirconia-toughened alumina (ZTA) ceramic composites. By adjusting TiO₂ content from 0 wt% to 5 wt% and employing advanced microwave sintering at 1150 °C, the study aims to lower the sintering temperature of ZTA. Microwave sintering, known for its efficiency and rapid processing, enables significant enhancements in material properties at reduced temperatures. Notably, incorporating TiO₂ into ZTA yields remarkable improvements in physical and mechanical attributes, with the optimal TiO₂ content determined to be 3 wt%. At this concentration, the composite achieves exceptional properties: a relative density of ∼99 %, microhardness of ∼2002 HV, and an indentation fracture toughness of ∼6.13 MPa m^0.5. These enhancements represent increases of over 120 % in hardness and 61 % in toughness compared to TiO₂-free ZTA. Additionally, the highest scratch resistance is observed at 3 wt% TiO₂, evidenced by a minimal scratch depth of ∼7.53 μm. However, exceeding the 3 wt% solubility limit results in the formation of secondary phases, such as tialite (Al₂TiO₅) and zirconium titanate (ZrTiO₄), which degrade the composite's properties. This research underscores the potential of TiO₂ doping and microwave sintering to elevate the performance of ZTA ceramics, offering a pathway to superior materials for advanced applications.