The Influence of Niobia Additions on Microstructure, Vickers Hardness and Indentation Fracture Resistance of ZTA Ceramic Composites

The effect of small additions of niobium pentoxide (Nb 2 O 5 ) from 0 to 0.7 wt% on the zirconia toughened alumina (ZTA) ceramics sintered at 1600 °C was studied. Based on the results, the small addition of Nb 2 O 5 was discovered to be able to significantly influence on phase, microstructure, and mechanical properties of ZTA ceramics. The presence of the secondary phase of Nb 2 Zr 6 O 17 as a square-shaped particle is confirmed by SEM and FESEM-EDX up to 0.5 weight percent (wt.%) of Nb 2 O 5 additions. The addition of 0.3 wt.% resulted in the highest Vickers hardness value of 1500 Vickers hardness (HV). However, it was found that adding Nb 2 O 5 more than 0.3 wt% causes ZTA's hardness and indentation fracture resistance (K IFR ) values to decline from 1500 HV to 1438 HV and 4.88 MPa.√m to 4.18 MPa.√m, respectively. Additionally, it was found that when the amount of Nb 2 O 5 added increased, the value for bulk density climbed while porosity reduced.